bims-medebr Biomed News
on Metabolism of the developing brain
Issue of 2024–06–30
38 papers selected by
Regina F. Fernández, Johns Hopkins University
  1. Multifactor Analyses of Frontal Cortex Lipids in the APP/PS1 Model of Familial Alzheimer's Disease Reveal Anomalies in Responses to Dietary n-3 PUFA and Estrogenic Treatments.
  2. Metabolic flexibility ensures proper neuronal network function in moderate neuroinflammation.
  3. Glyceraldehyde metabolism in mouse brain and the entry of blood-borne glyceraldehyde into the brain.
  4. Modulation of Brain Cholesterol Metabolism through CYP46A1 Overexpression for Rett Syndrome.
  5. Brain and serum lipidomic profiles implicate Lands cycle acyl chain remodeling association with APOEε4 and mild cognitive impairment.
  6. Mind the Metabolic Gap: Bridging Migraine and Alzheimer's disease through Brain Insulin Resistance.
  7. Lactate: a new target for brain disorders.
  8. Ischemic Brain Injury: Involvement of Lipids in the Pathophysiology of Stroke and Therapeutic Strategies.
  9. Mitochondrial DNA Instability Supersedes Parkin Mutations in Driving Mitochondrial Proteomic Alterations and Functional Deficits in Polg Mutator Mice.
  10. Sphingolipid changes in mouse brain and plasma after mild traumatic brain injury at the acute phases.
  11. Mitochondrial One-Carbon Metabolism and Alzheimer's Disease.
  12. The short-chain fatty acid acetate modulates orexin/hypocretin neurons: A novel mechanism in gut-brain axis regulation of energy homeostasis and feeding.
  13. Enterocyte-specific FATP4 deficiency elevates blood lipids via a shift from polar to neutral lipids in distal intestine.
  14. A fluorescent perilipin 2 knock-in mouse model reveals a high abundance of lipid droplets in the developing and adult brain.
  15. Metabolic channeling of lipids via the contact zones between different organelles.
  16. Loss of Slc35a2 alters development of the mouse cerebral cortex.
  17. Gangliosides in neural stem cell fate determination and nerve cell specification--preparation and administration.
  18. Neurochemical changes in the progression of Huntington's disease: A meta-analysis of in vivo1H-MRS studies.
  19. Microglia contribute to neuronal synchrony despite endogenous ATP-related phenotypic transformation in acute mouse brain slices.
  20. WNKs regulate mouse behavior and alter central nervous system glucose uptake and insulin signaling.
  21. Simultaneous arterial spin labeling functional MRI and fluorodeoxyglucose PET in mild chronic traumatic brain injury.
  22. Valine and Inflammation Drive Epilepsy in a Mouse Model of ECHS1 Deficiency.
  23. Omega-3 polyunsaturated fatty acids and Parkinson's disease: A systematic review of animal studies.
  24. Intermittent Fasting Induced Cerebral Ischemic Tolerance Altered Gut Microbiome and Increased Levels of Short-Chain Fatty Acids to a Beneficial Phenotype.
  25. The Effect of Neuronal CoQ10 Deficiency and Mitochondrial Dysfunction on a Rotenone-Induced Neuronal Cell Model of Parkinson's Disease.
  26. Critical Role of Mitochondrial Fatty Acid Metabolism in Normal Cell Function and Pathological Conditions.
  27. Tryptophan Metabolism in Alzheimer's Disease with the Involvement of Microglia and Astrocyte Crosstalk and Gut-Brain Axis.
  28. The Tryptophan Metabolite Indole-3-Propionic Acid Raises Kynurenic Acid Levels in the Rat Brain In Vivo.
  29. A comprehensive measure of Golgi sphingolipid flux using NBD C6-Ceramide: evaluation of sphingolipid inhibitors.
  30. Sphingosine kinase 2 regulates protein ubiquitination networks in neurons.
  31. Loss of neuronal lysosomal acid lipase drives amyloid pathology in Alzheimer's disease.
  32. Ethyl pyruvate alleviates NLRP3/Caspase-1/GSDMD-mediated neuronal pyroptosis in neonatal rats with hypoxic-ischemic brain damage.
  33. Efficacy and tolerability of classical and polyunsaturated fatty acids ketogenic diet in controlling paediatric refractory epilepsy - A randomized study.
  34. Omega-3 alleviates behavioral and molecular changes in a mouse model of stress-induced juvenile depression.
  35. Defective mitochondria-lysosomal axis enhances the release of extracellular vesicles containing mitochondrial DNA and proteins in Huntington's disease.
  36. Implications of mitochondrial membrane potential gradients on signaling and ATP production analyzed by correlative multi-parameter microscopy.
  37. Mitochondrial Dysfunction in Sporadic Amyotrophic Lateral Sclerosis Patients: Insights from High-Resolution Respirometry.
  38. A simplified method for preventing post-mortem alterations of brain prostanoids for true in situ level quantification.
  1. Genes (Basel). 2024 Jun 19. pii: 810. [Epub ahead of print]15(6):
    Multifactor Analyses of Frontal Cortex Lipids in the APP/PS1 Model of Familial Alzheimer's Disease Reveal Anomalies in Responses to Dietary n-3 PUFA and Estrogenic Treatments.
    Mario Díaz.
      Brain lipid homeostasis is an absolute requirement for proper functionality of nerve cells and neurological performance. Current evidence demonstrates that lipid alterations are linked to neurodegenerative diseases, especially Alzheimer's disease (AD). The complexity of the brain lipidome and its metabolic regulation has hampered the identification of critical processes associated with the onset and progression of AD. While most experimental studies have focused on the effects of known factors on the development of pathological hallmarks in AD, e.g., amyloid deposition, tau protein and neurofibrillary tangles, neuroinflammation, etc., studies addressing the causative effects of lipid alterations remain largely unexplored. In the present study, we have used a multifactor approach combining diets containing different amounts of polyunsaturated fatty acids (PUFAs), estrogen availabilities, and genetic backgrounds, i.e., wild type (WT) and APP/PS1 (FAD), to analyze the lipid phenotype of the frontal cortex in middle-aged female mice. First, we observed that severe n-3 PUFA deficiency impacts the brain n-3 long-chain PUFA (LCPUFA) composition, yet it was notably mitigated by hepatic de novo synthesis. n-6 LCPUFAs, ether-linked fatty acids, and saturates were also changed by the dietary condition, but the extent of changes was dependent on the genetic background and hormonal condition. Likewise, brain cortex phospholipids were mostly modified by the genotype (FAD>WT) with nuanced effects from dietary treatment. Cholesterol (but not sterol esters) was modified by the genotype (WT>FAD) and dietary condition (higher in DHA-free conditions, especially in WT mice). However, the effects of estrogen treatment were mostly observed in relation to phospholipid remodeling in a genotype-dependent manner. Analyses of lipid-derived variables indicate that nerve cell membrane biophysics were significantly affected by the three factors, with lower membrane microviscosity (higher fluidity) values obtained for FAD animals. In conclusion, our multifactor analyses revealed that the genotype, diet, and estrogen status modulate the lipid phenotype of the frontal cortex, both as independent factors and through their interactions. Altogether, the outcomes point to potential strategies based on dietary and hormonal interventions aimed at stabilizing the brain cortex lipid composition in Alzheimer's disease neuropathology.
    Keywords:  APP/PS1 mice; Alzheimer’s disease; LCPUFAs (long-chain polyunsaturated fatty acids); estrogens; membrane viscosity; neurolipids; phospholipid remodeling; plasmalogens
    DOI:  https://doi.org/10.3390/genes15060810
  2. Sci Rep. 2024 06 22. 14(1): 14405
    Metabolic flexibility ensures proper neuronal network function in moderate neuroinflammation.
    Bruno Chausse, Nikolai Malorny, Andrea Lewen, Gernot Poschet, Nikolaus Berndt, Oliver Kann.
      Microglia, brain-resident macrophages, can acquire distinct functional phenotypes, which are supported by differential reprogramming of cell metabolism. These adaptations include remodeling in glycolytic and mitochondrial metabolic fluxes, potentially altering energy substrate availability at the tissue level. This phenomenon may be highly relevant in the brain, where metabolism must be precisely regulated to maintain appropriate neuronal excitability and synaptic transmission. Direct evidence that microglia can impact on neuronal energy metabolism has been widely lacking, however. Combining molecular profiling, electrophysiology, oxygen microsensor recordings and mathematical modeling, we investigated microglia-mediated disturbances in brain energetics during neuroinflammation. Our results suggest that proinflammatory microglia showing enhanced nitric oxide release and decreased CX3CR1 expression transiently increase the tissue lactate/glucose ratio that depends on transcriptional reprogramming in microglia, not in neurons. In this condition, neuronal network activity such as gamma oscillations (30-70 Hz) can be fueled by increased ATP production in mitochondria, which is reflected by elevated oxygen consumption. During dysregulated inflammation, high energy demand and low glucose availability can be boundary conditions for neuronal metabolic fitness as revealed by kinetic modeling of single neuron energetics. Collectively, these findings indicate that metabolic flexibility protects neuronal network function against alterations in local substrate availability during moderate neuroinflammation.
    Keywords:  Glycolysis; Immunometabolism; Lactate oxidation; Microglia; Neuronal oscillations
    DOI:  https://doi.org/10.1038/s41598-024-64872-1
  3. J Neurochem. 2024 Jun 22.
    Glyceraldehyde metabolism in mouse brain and the entry of blood-borne glyceraldehyde into the brain.
    Bjørnar Hassel, Kristian Sørnes, Ahmed Elsais, Patricia Reyes Cordero, Anne Sofie Frøland, Frode Rise.
      D-Glyceraldehyde, a reactive aldehyde metabolite of fructose and glucose, is neurotoxic in vitro by forming advanced glycation end products (AGEs) with neuronal proteins. In Alzheimer's disease brains, glyceraldehyde-containing AGEs have been detected intracellularly and in extracellular plaques. However, little information exists on how the brain handles D-glyceraldehyde metabolically or if glyceraldehyde crosses the blood-brain barrier from the circulation into the brain. We injected [U-13C]-D-glyceraldehyde intravenously into awake mice and analyzed extracts of serum and brain by 13C nuclear magnetic resonance spectroscopy. 13C-Labeling of brain lactate and glutamate indicated passage of D-glyceraldehyde from blood to brain and glycolytic and oxidative D-glyceraldehyde metabolism in brain cells. 13C-Labeling of serum glucose and lactate through hepatic metabolism of [U-13C]-D-glyceraldehyde could not explain the formation of 13C-labeled lactate and glutamate in the brain. Cerebral glyceraldehyde dehydrogenase and reductase activities, leading to the formation of D-glycerate and glycerol, respectively, were 0.27-0.28 nmol/mg/min; triokinase, which phosphorylates D-glyceraldehyde to D-glyceraldehyde-3-phosphate, has been demonstrated previously at low levels. Thus, D-glyceraldehyde metabolism toward glycolysis could proceed both through D-glycerate, glycerol, and D-glyceraldehyde-3-phosphate. The aldehyde group of D-glyceraldehyde was overwhelmingly hydrated into a diol in aqueous solution, but the diol dehydration rate greatly exceeded glyceraldehyde metabolism and did not restrict it. We conclude that (1) D-glyceraldehyde crosses the blood-brain barrier, and so blood-borne glyceraldehyde could contribute to AGE formation in the brain, (2) glyceraldehyde is taken up and metabolized by brain cells. Metabolism thus constitutes a detoxification mechanism for this reactive aldehyde, a mechanism that may be compromised in disease states.
    Keywords:  Alzheimer's disease; advanced glycation end product; blood–brain barrier; diabetes; diol dehydration; glyceraldehyde
    DOI:  https://doi.org/10.1111/jnc.16158
  4. Pharmaceutics. 2024 Jun 03. pii: 756. [Epub ahead of print]16(6):
    Modulation of Brain Cholesterol Metabolism through CYP46A1 Overexpression for Rett Syndrome.
    Emilie Audouard, Nicolas Khefif, Béatrix Gillet-Legrand, Fanny Nobilleau, Ouafa Bouazizi, Serena Stanga, Gaëtan Despres, Sandro Alves, Antonin Lamazière, Nathalie Cartier, Françoise Piguet.
      Rett syndrome (RTT) is a rare neurodevelopmental disorder caused by mutation in the X-linked gene methyl-CpG-binding protein 2 (Mecp2), a ubiquitously expressed transcriptional regulator. RTT results in mental retardation and developmental regression that affects approximately 1 in 10,000 females. Currently, there is no curative treatment for RTT. Thus, it is crucial to develop new therapeutic approaches for children suffering from RTT. Several studies suggested that RTT is linked with defects in cholesterol homeostasis, but for the first time, therapeutic evaluation is carried out by modulating this pathway. Moreover, AAV-based CYP46A1 overexpression, the enzyme involved in cholesterol pathway, has been demonstrated to be efficient in several neurodegenerative diseases. Based on these data, we strongly believe that CYP46A1 could be a relevant therapeutic target for RTT. Herein, we evaluated the effects of intravenous AAVPHP.eB-hCYP46A1-HA delivery in male and female Mecp2-deficient mice. The applied AAVPHP.eB-hCYP46A1 transduced essential neurons of the central nervous system (CNS). CYP46A1 overexpression alleviates behavioral alterations in both male and female Mecp2 knockout mice and extends the lifespan in Mecp2-deficient males. Several parameters related to cholesterol pathway are improved and correction of mitochondrial activity is demonstrated in treated mice, which highlighted the clear therapeutic benefit of CYP46A1 through the neuroprotection effect. IV delivery of AAVPHP.eB-CYP46A1 is perfectly well tolerated with no inflammation observed in the CNS of the treated mice. Altogether, our results strongly suggest that CYP46A1 is a relevant target and overexpression could alleviate the phenotype of Rett patients.
    Keywords:  AAVPHP.eB; Rett syndrome; cholesterol pathway; gene therapy
    DOI:  https://doi.org/10.3390/pharmaceutics16060756
  5. Front Aging Neurosci. 2024 ;16 1419253
    Brain and serum lipidomic profiles implicate Lands cycle acyl chain remodeling association with APOEε4 and mild cognitive impairment.
    Jason Mares, Ana Paula Costa, William J Dartora, Krista M Wartchow, Artur Lazarian, David A Bennett, Tal Nuriel, Vilas Menon, Laura Beth J McIntire.
       Introduction: At least one-third of the identified risk alleles from Genome-Wide Association Studies (GWAS) of Alzheimer's disease (AD) are involved in lipid metabolism, lipid transport, or direct lipid binding. In fact, a common genetic variant (ε4) in a cholesterol and phospholipid transporter, Apolipoprotein E (APOEε4), is the primary genetic risk factor for late-onset AD. In addition to genetic variants, lipidomic studies have reported severe metabolic dysregulation in human autopsy brain tissue, cerebrospinal fluid, blood, and multiple mouse models of AD.
    Methods: We aimed to identify an overarching metabolic pathway in lipid metabolism by integrating analyses of lipidomics and transcriptomics from the Religious Order Study and Rush Memory Aging Project (ROSMAP) using differential analysis and network correlation analysis.
    Results: Coordinated differences in lipids were found to be dysregulated in association with both mild cognitive impairment (MCI) and APOEε4 carriers. Interestingly, these correlations were weakened when adjusting for education. Indeed, the cognitively non-impaired APOEε4 carriers have higher education levels in the ROSMAP cohort, suggesting that this lipid signature may be associated with a resilience phenotype. Network correlation analysis identified multiple differential lipids within a single module that are substrates and products in the Lands Cycle for acyl chain remodeling. In addition, our analyses identified multiple genes in the Lands Cycle acyl chain remodeling pathway, which were associated with cognitive decline independent of amyloid-β (Aβ) load and tau tangle pathologies.
    Discussion: Our studies highlight the critical differences in acyl chain remodeling in brain tissue from APOEε4 carriers and individual non-carriers with MCI. A coordinated lipid profile shift in dorsolateral prefrontal cortex from both APOEε4 carriers and MCI suggests differences in lipid metabolism occur early in disease stage and highlights lipid homeostasis as a tractable target for early disease modifying intervention.
    Keywords:  Alzheimer’s disease; ApoE; ROSMAP; lipid metabolism; lipidomics
    DOI:  https://doi.org/10.3389/fnagi.2024.1419253
  6. Aging Dis. 2024 Jun 16.
    Mind the Metabolic Gap: Bridging Migraine and Alzheimer's disease through Brain Insulin Resistance.
    Lorenzo Del Moro, Elenamaria Pirovano, Eugenia Rota.
      Brain insulin resistance has recently been described as a metabolic abnormality of brain glucose homeostasis that has been proven to downregulate insulin receptors, both in astrocytes and neurons, triggering a reduction in glucose uptake and glycogen synthesis. This condition may generate a mismatch between brain's energy reserve and expenditure, mainly during high metabolic demand, which could be involved in the chronification of migraine and, in the long run, at least in certain subsets of patients, in the prodromic phase of Alzheimer's disease, along a putative metabolic physiopathological continuum. Indeed, the persistent disruption of glucose homeostasis and energy supply to neurons may eventually impair protein folding, an energy-requiring process, promoting pathological changes in Alzheimer's disease, such as amyloid-β deposition and tau hyperphosphorylation. Hopefully, the "neuroenergetic hypothesis" presented herein will provide further insight on there being a conceivable metabolic bridge between chronic migraine and Alzheimer's disease, elucidating novel potential targets for the prophylactic treatment of both diseases.
    DOI:  https://doi.org/10.14336/AD.2024.0351
  7. Neuroscience. 2024 Jun 25. pii: S0306-4522(24)00280-X. [Epub ahead of print]
    Lactate: a new target for brain disorders.
    Shunfeng Liu, Shouhong Zhou.
      Lactate in the brain is produced endogenously and exogenously. The primary functional cells that produce lactate in the brain are astrocytes. Astrocytes release lactate to act on neurons, thereby affecting neuronal function, through a process known as the astrocyte-neuron shuttle. Lactate affects microglial function as well and inhibits microglia-mediated neuroinflammation. Lactate also provides energy, acts as a signaling molecule, and promotes neurogenesis. This article summarizes the role of lactate in cells, animals, and humans. Lactate is a protective molecule against stress in healthy organisms and in the early stages of brain disorders. Thus, lactate may be a potential therapeutic target for brain disorders. Further research on the role of lactate in microglia may have great prospects. This article provides a new perspective and research direction for the study of lacate in brain disorders.
    Keywords:  Lactate; depression; microglia; neurogenesis; neuroinflammation; signaling molecules
    DOI:  https://doi.org/10.1016/j.neuroscience.2024.06.023
  8. Antioxidants (Basel). 2024 May 23. pii: 634. [Epub ahead of print]13(6):
    Ischemic Brain Injury: Involvement of Lipids in the Pathophysiology of Stroke and Therapeutic Strategies.
    Nathalie Bernoud-Hubac, Amanda Lo Van, Adina-Nicoleta Lazar, Michel Lagarde.
      Stroke is a devastating neurological disorder that is characterized by the sudden disruption of blood flow to the brain. Lipids are essential components of brain structure and function and play pivotal roles in stroke pathophysiology. Dysregulation of lipid signaling pathways modulates key cellular processes such as apoptosis, inflammation, and oxidative stress, exacerbating ischemic brain injury. In the present review, we summarize the roles of lipids in stroke pathology in different models (cell cultures, animal, and human studies). Additionally, the potential of lipids, especially polyunsaturated fatty acids, to promote neuroprotection and their use as biomarkers in stroke are discussed.
    Keywords:  brain; ischemic stroke; lipids; oxidative stress; therapeutic strategies
    DOI:  https://doi.org/10.3390/antiox13060634
  9. Int J Mol Sci. 2024 Jun 11. pii: 6441. [Epub ahead of print]25(12):
    Mitochondrial DNA Instability Supersedes Parkin Mutations in Driving Mitochondrial Proteomic Alterations and Functional Deficits in Polg Mutator Mice.
    Andrew J Trease, Steven Totusek, Eliezer Z Lichter, Kelly L Stauch, Howard S Fox.
      Mitochondrial quality control is essential in mitochondrial function. To examine the importance of Parkin-dependent mechanisms in mitochondrial quality control, we assessed the impact of modulating Parkin on proteome flux and mitochondrial function in a context of reduced mtDNA fidelity. To accomplish this, we crossed either the Parkin knockout mouse or ParkinW402A knock-in mouse lines to the Polg mitochondrial mutator line to generate homozygous double mutants. In vivo longitudinal isotopic metabolic labeling was followed by isolation of liver mitochondria and synaptic terminals from the brain, which are rich in mitochondria. Mass spectrometry and bioenergetics analysis were assessed. We demonstrate that slower mitochondrial protein turnover is associated with loss of mtDNA fidelity in liver mitochondria but not synaptic terminals, and bioenergetic function in both tissues is impaired. Pathway analysis revealed loss of mtDNA fidelity is associated with disturbances of key metabolic pathways, consistent with its association with metabolic disorders and neurodegeneration. Furthermore, we find that loss of Parkin leads to exacerbation of Polg-driven proteomic consequences, though it may be bioenergetically protective in tissues exhibiting rapid mitochondrial turnover. Finally, we provide evidence that, surprisingly, dis-autoinhibition of Parkin (ParkinW402A) functionally resembles Parkin knockout and fails to rescue deleterious Polg-driven effects. Our study accomplishes three main outcomes: (1) it supports recent studies suggesting that Parkin dependence is low in response to an increased mtDNA mutational load, (2) it provides evidence of a potential protective role of Parkin insufficiency, and (3) it draws into question the therapeutic attractiveness of enhancing Parkin function.
    Keywords:  Parkin; Parkinson’s disease; aging; metabolism; mitochondria; mitophagy
    DOI:  https://doi.org/10.3390/ijms25126441
  10. Lipids Health Dis. 2024 Jun 27. 23(1): 200
    Sphingolipid changes in mouse brain and plasma after mild traumatic brain injury at the acute phases.
    Koushik Mondal, Nobel A Del Mar, Ashlyn A Gary, Richard C Grambergs, Mohd Yousuf, Faiza Tahia, Benjamin Stephenson, Daniel J Stephenson, Charles E Chalfant, Anton Reiner, Nawajes Mandal.
       BACKGROUND: Traumatic brain injury (TBI) causes neuroinflammation and can lead to long-term neurological dysfunction, even in cases of mild TBI (mTBI). Despite the substantial burden of this disease, the management of TBI is precluded by an incomplete understanding of its cellular mechanisms. Sphingolipids (SPL) and their metabolites have emerged as key orchestrators of biological processes related to tissue injury, neuroinflammation, and inflammation resolution. No study so far has investigated comprehensive sphingolipid profile changes immediately following TBI in animal models or human cases. In this study, sphingolipid metabolite composition was examined during the acute phases in brain tissue and plasma of mice following mTBI.
    METHODS: Wildtype mice were exposed to air-blast-mediated mTBI, with blast exposure set at 50-psi on the left cranium and 0-psi designated as Sham. Sphingolipid profile was analyzed in brain tissue and plasma during the acute phases of 1, 3, and 7 days post-TBI via liquid-chromatography-mass spectrometry. Simultaneously, gene expression of sphingolipid metabolic markers within brain tissue was analyzed using quantitative reverse transcription-polymerase chain reaction. Significance (P-values) was determined by non-parametric t-test (Mann-Whitney test) and by Tukey's correction for multiple comparisons.
    RESULTS: In post-TBI brain tissue, there was a significant elevation of 1) acid sphingomyelinase (aSMase) at 1- and 3-days, 2) neutral sphingomyelinase (nSMase) at 7-days, 3) ceramide-1-phosphate levels at 1 day, and 4) monohexosylceramide (MHC) and sphingosine at 7-days. Among individual species, the study found an increase in C18:0 and a decrease in C24:1 ceramides (Cer) at 1 day; an increase in C20:0 MHC at 3 days; decrease in MHC C18:0 and increase in MHC C24:1, sphingomyelins (SM) C18:0, and C24:0 at 7 days. Moreover, many sphingolipid metabolic genes were elevated at 1 day, followed by a reduction at 3 days and an absence at 7-days post-TBI. In post-TBI plasma, there was 1) a significant reduction in Cer and MHC C22:0, and an increase in MHC C16:0 at 1 day; 2) a very significant increase in long-chain Cer C24:1 accompanied by significant decreases in Cer C24:0 and C22:0 in MHC and SM at 3 days; and 3) a significant increase of C22:0 in all classes of SPL (Cer, MHC and SM) as well as a decrease in Cer C24:1, MHC C24:1 and MHC C24:0 at 7 days.
    CONCLUSIONS: Alterations in sphingolipid metabolite composition, particularly sphingomyelinases and short-chain ceramides, may contribute to the induction and regulation of neuroinflammatory events in the early stages of TBI, suggesting potential targets for novel diagnostic, prognostic, and therapeutic strategies in the future.
    Keywords:  Ceramide; Inflammation; Sphingolipid; Sphingomyelin; Sphingomyelinase; Traumatic brain injury
    DOI:  https://doi.org/10.1186/s12944-024-02186-x
  11. Int J Mol Sci. 2024 Jun 07. pii: 6302. [Epub ahead of print]25(12):
    Mitochondrial One-Carbon Metabolism and Alzheimer's Disease.
    Yizhou Yu, L Miguel Martins.
      Mitochondrial one-carbon metabolism provides carbon units to several pathways, including nucleic acid synthesis, mitochondrial metabolism, amino acid metabolism, and methylation reactions. Late-onset Alzheimer's disease is the most common age-related neurodegenerative disease, characterised by impaired energy metabolism, and is potentially linked to mitochondrial bioenergetics. Here, we discuss the intersection between the molecular pathways linked to both mitochondrial one-carbon metabolism and Alzheimer's disease. We propose that enhancing one-carbon metabolism could promote the metabolic processes that help brain cells cope with Alzheimer's disease-related injuries. We also highlight potential therapeutic avenues to leverage one-carbon metabolism to delay Alzheimer's disease pathology.
    Keywords:  Alzheimer’s disease; folate; mitochondria; one-carbon metabolism
    DOI:  https://doi.org/10.3390/ijms25126302
  12. Biochem Pharmacol. 2024 Jun 20. pii: S0006-2952(24)00366-6. [Epub ahead of print]226 116383
    The short-chain fatty acid acetate modulates orexin/hypocretin neurons: A novel mechanism in gut-brain axis regulation of energy homeostasis and feeding.
    Nicola Forte, Brenda Marfella, Alessandro Nicois, Letizia Palomba, Debora Paris, Andrea Motta, Maria Pina Mollica, Vincenzo Di Marzo, Luigia Cristino.
      The short-chain fatty acids (SCFAs) acetate, propionate and butyrate, the major products of intestinal microbial fermentation of dietary fibres, are involved in fine-tuning brain functions via the gut-brain axis. However, the effects of SCFAs in the hypothalamic neuronal network regulating several autonomic-brain functions are still unknown. Using NMR spectroscopy, we detected a reduction in brain acetate concentrations in the hypothalamus of obese leptin knockout ob/ob mice compared to lean wild-type littermates. Therefore, we investigated the effect of acetate on orexin/hypocretin neurons (hereafter referred as OX or OX-A neurons), a subset of hypothalamic neurons regulating energy homeostasis, which we have characterized in previous studies to be over-activated by the lack of leptin and enhancement of endocannabinoid tone in the hypothalamus of ob/ob mice. We found that acetate reduces food-intake in concomitance with a reduction of orexin neuronal activity in ob/ob mice. This was demonstrated by evaluating food-intake behaviour and orexin-A/c-FOS immunoreactivity coupled with patch-clamp recordings in Hcrt-eGFP neurons, quantification of prepro-orexin mRNA, and immunolabeling of GPR-43, the main acetate receptor. Our data provide new insights into the mechanisms of the effects of chronic dietary supplementation with acetate, or complex carbohydrates, on energy intake and body weight, which may be partly mediated by inhibition of orexinergic neuron activity.
    Keywords:  Endocannabinoids; Hcrt; Microbiota; Obesity; SCFAs
    DOI:  https://doi.org/10.1016/j.bcp.2024.116383
  13. Am J Physiol Gastrointest Liver Physiol. 2024 Jun 25.
    Enterocyte-specific FATP4 deficiency elevates blood lipids via a shift from polar to neutral lipids in distal intestine.
    Jessica Seeßle, Gerhard Liebisch, Simone Staffer, Sabine Tuma-Kellner, Uta Merle, Thomas Herrmann, Walee Chamulitrat.
      FATP4 was thought to mediate intestinal lipid absorption which was disputed by a study using keratinocyte-Fatp4-rescued Fatp4-/- mice. These knockouts when fed with a western diet showed elevated intestinal triglyceride (TG) and fatty-acid levels. To investigate a possible role of FATP4 on intestinal lipid processing, ent-Fatp4 (KO) mice were generated by Villin-Cre-specific inactivation of the Fatp4 gene. We aimed to measure circulating and intestinal lipids in control and KO mice after acute or chronic fat intake or during ageing. Remarkably, ent-Fatp4 mice displayed a ~30% decrease in ileal behenic, lignoceric, and nervonic acids, ceramides containing these FA, as well as, ileal sphingomyelin, phosphatidylcholine, and phosphatidylinositol levels. Such decreases were concomitant with an increase in jejunal cholesterol ester. After 2-week recovery from high lipid overload by tyloxapol and oral-lipid treatment, ent-Fatp4 mice showed an increase in plasma TG and chylomicrons. Upon overnight fasting followed by an oral fat meal, ent-Fatp4 mice showed an increase in plasma TG-rich lipoproteins and particle number of chylomicrons and very low-density lipoproteins. During ageing or after feeding with a high-fat high-cholesterol (HFHC) diet, ent-Fatp4 mice showed an increase in plasma TG, fatty acids, glycerol, and lipoproteins as well as intestinal lipids. HFHC-fed KO mice displayed an increase in body weights, the numbers of lipid droplets with larger sizes in the ileum concomitant with a decrease in ileal ceramides and phosphatidylcholine. Thus, enterocyte FATP4 deficiency led to a metabolic shift from polar to neutral lipids in distal intestine rendering an increase in plasma lipids and lipoproteins.
    Keywords:  ageing; fat absorption; fatty acid transport proteins; high-fat high-cholesterol diets; lipoprotiens
    DOI:  https://doi.org/10.1152/ajpgi.00109.2024
  14. Nat Commun. 2024 Jun 28. 15(1): 5489
    A fluorescent perilipin 2 knock-in mouse model reveals a high abundance of lipid droplets in the developing and adult brain.
    Sofia Madsen, Ana C Delgado, Christelle Cadilhac, Vanille Maillard, Fabrice Battiston, Carla Marie Igelbüscher, Simon De Neck, Elia Magrinelli, Denis Jabaudon, Ludovic Telley, Fiona Doetsch, Marlen Knobloch.
      Lipid droplets (LDs) are dynamic lipid storage organelles. They are tightly linked to metabolism and can exert protective functions, making them important players in health and disease. Most LD studies in vivo rely on staining methods, providing only a snapshot. We therefore developed a LD-reporter mouse by labelling the endogenous LD coat protein perilipin 2 (PLIN2) with tdTomato, enabling staining-free fluorescent LD visualisation in living and fixed tissues and cells. Here we validate this model under standard and high-fat diet conditions and demonstrate that LDs are highly abundant in various cell types in the healthy brain, including neurons, astrocytes, ependymal cells, neural stem/progenitor cells and microglia. Furthermore, we also show that LDs are abundant during brain development and can be visualized using live imaging of embryonic slices. Taken together, our tdTom-Plin2 mouse serves as a novel tool to study LDs and their dynamics under both physiological and diseased conditions in all tissues expressing Plin2.
    DOI:  https://doi.org/10.1038/s41467-024-49449-w
  15. Bioessays. 2024 Jun 27. e2400045
    Metabolic channeling of lipids via the contact zones between different organelles.
    Kentaro Hanada.
      Various lipid transfer proteins (LTPs) mediate the inter-organelle transport of lipids. By working at membrane contact zones between donor and acceptor organelles, LTPs achieve rapid and accurate inter-organelle transfer of lipids. This article will describe the emerging paradigm that the action of LTPs at organelle contact zones generates metabolic channeling events in lipid metabolism, mainly referring to how ceramide synthesized in the endoplasmic reticulum is preferentially metabolized to sphingomyelin in the distal Golgi region, how cholesterol and phospholipids receive specific metabolic reactions in mitochondria, and how the hijacking of host LTPs by intracellular pathogens may generate new channeling-like events. In addition, the article will discuss how the function of LTPs is regulated, exemplified by a few representative LTP systems, and will briefly touch on experiments that will be necessary to establish the paradigm that LTP-mediated inter-organelle transport of lipids is one of the mechanisms of compartmentalization-based metabolic channeling events.
    Keywords:  cholesterol; compartmentalization; lipid transfer proteins; metabolic channeling; organelle contact; sphingolipids
    DOI:  https://doi.org/10.1002/bies.202400045
  16. Neurosci Lett. 2024 Jun 21. pii: S0304-3940(24)00259-3. [Epub ahead of print] 137881
    Loss of Slc35a2 alters development of the mouse cerebral cortex.
    Soad Elziny, Sahibjot Sran, Hyojung Yoon, Rachel R Corrigan, John Page, Amanda Ringland, Anna Lanier, Sara Lapidus, James Foreman, Erin L Heinzen, Philip Iffland, Peter B Crino, Tracy A Bedrosian.
      Brain somatic variants in SLC35A2, an intracellular UDP-galactose transporter, are commonly identified mutations associated with drug-resistant neocortical epilepsy and developmental brain malformations, including focal cortical dysplasia type I and mild malformation of cortical development with oligodendroglial hyperplasia in epilepsy (MOGHE). However, the causal effects of altered SLC35A2 function on cortical development remain untested. We hypothesized that focal Slc35a2 knockout (KO) or knockdown (KD) in the developing mouse cortex would disrupt cortical development and change network excitability. Through two independent studies, we used in utero electroporation (IUE) to introduce CRISPR/Cas9/targeted guide RNAs or short-hairpin RNAs into the embryonic mouse brain at day 14.5-15.5 to achieve Slc35a2 KO or KD, respectively, from neural precursor cells. Slc35a2 KO or KD caused disrupted radial migration of electroporated neurons evidenced by heterotopic cells located in lower cortical layers and in the sub-cortical white matter. Slc35a2 KO in neurons did not induce changes in oligodendrocyte number, importantly suggesting that the oligodendroglial hyperplasia observed in MOGHE originates from distinct cell autonomous effects of Slc35a2 mutations. Adult KO mice were implanted with EEG electrodes for 72-hour continuous recording. Spontaneous seizures were not observed in focal Slc35a2 KO mice, but there was reduced seizure threshold following pentylenetetrazol injection. Here we demonstrate that focal Slc35a2 KO or KD in vivo disrupts corticogenesis through altered neuronal migration and that KO leads to reduced seizure threshold. Together these results demonstrate a direct causal role for SLC35A2 in cortical development.
    Keywords:  CRISPR; Cerebral cortex; Cortical dysplasia; Glycosylation; Short-hairpin RNA
    DOI:  https://doi.org/10.1016/j.neulet.2024.137881
  17. bioRxiv. 2024 Jun 11. pii: 2024.06.09.598109. [Epub ahead of print]
    Gangliosides in neural stem cell fate determination and nerve cell specification--preparation and administration.
    Yutaka Itokazu, Toshio Ariga, Takahiro Fuchigami, Dongpei Li.
      Gangliosides are sialylated glycosphingolipids with essential but enigmatic functions in healthy and disease brains. GD3 is the predominant species in neural stem cells (NSCs) and GD3-synthase (sialyltransferase II; St8Sia1 ) knockout (GD3S-KO) revealed reduction of postnatal NSC pools with severe behavioral deficits including cognitive impairment, depression-like phenotypes, and olfactory dysfunction. Exogenous administration of GD3 significantly restored the NSC pools and enhanced the stemness of NSCs with multipotency and self-renewal, followed by restored neuronal functions. Our group discovered that GD3 is involved in the maintenance of NSC fate determination by interacting with epidermal growth factor receptors (EGFRs), by modulating expression of cyclin-dependent kinase (CDK) inhibitors p27 and p21, and by regulating mitochondrial dynamics via associating a mitochondrial fission protein, the dynamin-related protein-1 (Drp1). Furthermore, we discovered that nuclear GM1 promotes neuronal differentiation by an epigenetic regulatory mechanism. GM1 binds with acetylated histones on the promoter of N-acetylgalactosaminyltransferase (GalNAcT; GM2 synthase (GM2S); B4galnt1) as well as on the NeuroD1 in differentiated neurons. In addition, epigenetic activation of the GM2S gene was detected as accompanied by an apparent induction of neuronal differentiation in NSCs responding to an exogenous supplement of GM1. Interestingly, GM1 induced epigenetic activation of the tyrosine hydroxylase (TH) gene, with recruitment of Nurr1 and PITX3, dopaminergic neuron-associated transcription factors, to the TH promoter region. In this way, GM1 epigenetically regulates dopaminergic neuron specific gene expression, and it would modify Parkinson's disease. Multifunctional gangliosides significantly modulate lipid microdomains to regulate functions of important molecules on multiple sites: the plasma membrane, mitochondrial membrane, and nuclear membrane. Versatile gangliosides regulate functional neurons as well as sustain NSC functions via modulating protein and gene activities on ganglioside microdomains. Maintaining proper ganglioside microdomains benefits healthy neuronal development and millions of senior citizens with neurodegenerative diseases. Here, we introduce how to isolate GD3 and GM1 and how to administer them into the mouse brain to investigate their functions on NSC fate determination and nerve cell specification.
    DOI:  https://doi.org/10.1101/2024.06.09.598109
  18. Neurobiol Dis. 2024 Jun 22. pii: S0969-9961(24)00174-8. [Epub ahead of print]199 106574
    Neurochemical changes in the progression of Huntington's disease: A meta-analysis of in vivo1H-MRS studies.
    Yinghua Jing, Imis Dogan, Kathrin Reetz, Sandro Romanzetti.
      Proton magnetic resonance spectroscopy (1H-MRS) allows measuring specific brain metabolic alterations in Huntington's disease (HD), and these metabolite profiles may serve as non-invasive biomarkers associated with disease progression. Despite this potential, previous findings are inconsistent. Accordingly, we performed a meta-analysis on available in vivo1H-MRS studies in premanifest (Pre-HD) and symptomatic HD stages (Symp-HD), and quantified neurometabolic changes relative to controls in 9 Pre-HD studies (227 controls and 188 mutation carriers) and 14 Symp-HD studies (326 controls and 306 patients). Our results indicated decreased N-acetylaspartate and creatine in the basal ganglia in both Pre-HD and Symp-HD. The overall level of myo-inositol was decreased in Pre-HD while increased in Symp-HD. Besides, Symp-HD patients showed more severe metabolism disruption than Pre-HD patients. Taken together, 1H-MRS is important for elucidating progressive metabolite changes from Pre-HD to clinical conversion; N-acetylaspartate and creatine in the basal ganglia are already sensitive at the preclinical stage and are promising biomarkers for tracking disease progression; overall myo-inositol is a possible characteristic metabolite for distinguishing HD stages.
    Keywords:  Biomarker; Brain metabolite; Premanifest Huntington's disease; Proton magnetic resonance spectroscopy; Symptomatic Huntington's disease
    DOI:  https://doi.org/10.1016/j.nbd.2024.106574
  19. Nat Commun. 2024 Jun 26. 15(1): 5402
    Microglia contribute to neuronal synchrony despite endogenous ATP-related phenotypic transformation in acute mouse brain slices.
    Péter Berki, Csaba Cserép, Zsuzsanna Környei, Balázs Pósfai, Eszter Szabadits, Andor Domonkos, Anna Kellermayer, Miklós Nyerges, Xiaofei Wei, Istvan Mody, Araki Kunihiko, Heinz Beck, He Kaikai, Wang Ya, Nikolett Lénárt, Zhaofa Wu, Miao Jing, Yulong Li, Attila I Gulyás, Ádám Dénes.
      Acute brain slices represent a workhorse model for studying the central nervous system (CNS) from nanoscale events to complex circuits. While slice preparation inherently involves tissue damage, it is unclear how microglia, the main immune cells and damage sensors of the CNS react to this injury and shape neuronal activity ex vivo. To this end, we investigated microglial phenotypes and contribution to network organization and functioning in acute brain slices. We reveal time-dependent microglial phenotype changes influenced by complex extracellular ATP dynamics through P2Y12R and CX3CR1 signalling, which is sustained for hours in ex vivo mouse brain slices. Downregulation of P2Y12R and changes of microglia-neuron interactions occur in line with alterations in the number of excitatory and inhibitory synapses over time. Importantly, functional microglia modulate synapse sprouting, while microglial dysfunction results in markedly impaired ripple activity both ex vivo and in vivo. Collectively, our data suggest that microglia are modulators of complex neuronal networks with important roles to maintain neuronal network integrity and activity. We suggest that slice preparation can be used to model time-dependent changes of microglia-neuron interactions to reveal how microglia shape neuronal circuits in physiological and pathological conditions.
    DOI:  https://doi.org/10.1038/s41467-024-49773-1
  20. bioRxiv. 2024 Jun 22. pii: 2024.06.09.598125. [Epub ahead of print]
    WNKs regulate mouse behavior and alter central nervous system glucose uptake and insulin signaling.
    Ankita B Jaykumar, Derk Binns, Clinton A Taylor, Anthony Anselmo, Shari G Birnbaum, Kimberly M Huber, Melanie H Cobb.
      Certain areas of the brain involved in episodic memory and behavior, such as the hippocampus, express high levels of insulin receptors and glucose transporter-4 (GLUT4) and are responsive to insulin. Insulin and neuronal glucose metabolism improve cognitive functions and regulate mood in humans. Insulin-dependent GLUT4 trafficking has been extensively studied in muscle and adipose tissue, but little work has demonstrated either how it is controlled in insulin-responsive brain regions or its mechanistic connection to cognitive functions. In this study, we demonstrate that inhibition of WNK (With-No-lysine (K)) kinases improves learning and memory in mice. Neuronal inhibition of WNK enhances in vivo hippocampal glucose uptake. Inhibition of WNK enhances insulin signaling output and insulin-dependent GLUT4 trafficking to the plasma membrane in mice primary neuronal cultures and hippocampal slices. Therefore, we propose that the extent of neuronal WNK kinase activity has an important influence on learning, memory and anxiety-related behaviors, in part, by modulation of neuronal insulin signaling.
    DOI:  https://doi.org/10.1101/2024.06.09.598125
  21. J Neuroradiol. 2024 Jun 20. pii: S0150-9861(24)00138-X. [Epub ahead of print]51(5): 101211
    Simultaneous arterial spin labeling functional MRI and fluorodeoxyglucose PET in mild chronic traumatic brain injury.
    Justin Heholt, Riya Patel, Faezeh Vedaei, George Zabrecky, Nancy Wintering, Daniel A Monti, Ze Wang, Andrew B Newberg, Feroze B Mohamed.
       BACKGROUND AND PURPOSE: To determine the effect of mild chronic traumatic brain injury (cTBI) on cerebral blood flow and metabolism.
    METHODS: 62 cTBI and 40 healthy controls (HCs) with no prior history of cTBI underwent both pulsed arterial spin labeling functional magnetic resonance imaging (PASL-fMRI) and fluorodeoxyglucose positron emission tomography (FDG-PET) scanning via a Siemens mMR (simultaneous PET/MRI) scanner. 30 participants also took part in a series of neuropsychological clinical measures (NCMs). Images were processed using statistical parametric mapping software relevant to each modality to generate relative cerebral blood flow (rCBF) and glucose metabolic standardized uptake value ratio (gSUVR) grey matter maps. A voxel-wise two-sample T-test and two-tailed gaussian random field correction for multiple comparisons was performed.
    RESULTS: cTBI patients showed a significant increase in rCBF and gSUVR in the right thalamus as well as a decrease in bilateral occipital lobes and calcarine sulci. An inverse relationship between rCBF and gSUVR was found in the left frontal lobe, the left precuneus and regions in the right temporal lobe. Within those regions rCBF values correlated with 9 distinct NCMs and gSUVR with 3.
    CONCLUSION: Simultaneous PASL-fMRI and FDG-PET can identify functional changes in a mild cTBI population. Within this population FDG-PET identified more regions of functional disturbance than ASL fMRI and NCMs are shown to correlate with rCBF and glucose metabolism (gSUVR) in various brain regions. As a result, both imaging modalities contribute to understanding the underlying pathophysiology and clinical course of mild chronic traumatic brain injury.
    Keywords:  ASL-fMRI; Cerebral Blood Flow; Cerebral Glucose Metabolism; Concussion; FDG-PET; TBI
    DOI:  https://doi.org/10.1016/j.neurad.2024.101211
  22. bioRxiv. 2024 Jun 13. pii: 2024.06.13.598697. [Epub ahead of print]
    Valine and Inflammation Drive Epilepsy in a Mouse Model of ECHS1 Deficiency.
    Meghan M Eller, Aamir R Zuberi, Xiaorong Fu, Shawn C Burgess, Cathleen M Lutz, Rachel M Bailey.
      ECHS1 Deficiency (ECHS1D) is a rare and devastating pediatric disease that currently has no defined treatments. This disorder results from missense loss-of-function mutations in the ECHS1 gene that result in severe developmental delays, encephalopathy, hypotonia, and early death. ECHS1 enzymatic activity is necessary for the beta-oxidation of fatty acids and the oxidation of branched-chain amino acids within the inner mitochondrial matrix. The pathogenesis of disease remains unknown, however it is hypothesized that disease is driven by an accumulation of toxic metabolites from impaired valine oxidation. To expand our knowledge on disease mechanisms, a novel mouse model of ECHS1D was generated that possesses a disease-associated knock-in (KI) allele and a knock-out (KO) allele. To investigate the behavioral phenotype, a battery of testing was performed at multiple time points, which included assessments of learning, motor function, endurance, sensory responses, and anxiety. Neurological abnormalities were assessed using wireless telemetry EEG recordings, pentylenetetrazol (PTZ) seizure induction, and immunohistochemistry. Metabolic perturbations were measured within the liver, serum, and brain using mass spectrometry and magnetic resonance spectroscopy. To test disease mechanisms, mice were subjected to disease pathway stressors and then survival, body weight gain, and epilepsy were assessed. Mice containing KI/KI or KI/KO alleles were viable with normal development and survival, and the presence of KI and KO alleles resulted in a significant reduction in ECHS1 protein. ECHS1D mice displayed reduced exercise capacity and pain sensation. EEG analysis revealed increased slow wave power that was associated with perturbations in sleep. ECHS1D mice had significantly increased epileptiform EEG discharges, and were sensitive to seizure induction, which resulted in death of 60% of ECHS1D mice. Under basal conditions, brain structure was grossly normal, although histological analysis revealed increased microglial activation in aged ECHS1D mice. Increased dietary valine only affected ECHS1D mice, which significantly exacerbated seizure susceptibility and resulted in death. Lastly, acute inflammatory challenge drove regression and early lethality in ECHS1D mice. In conclusion, we developed a novel model of ECHS1D that may be used to further knowledge on disease mechanisms and to develop therapeutics. Our data suggests altered metabolic signaling and inflammation may contribute to epilepsy in ECHS1D, and these alterations may be attributed to impaired valine metabolism.
    DOI:  https://doi.org/10.1101/2024.06.13.598697
  23. J Neurochem. 2024 Jun 24.
    Omega-3 polyunsaturated fatty acids and Parkinson's disease: A systematic review of animal studies.
    Barbara da Silva Alves, Lucia Emanueli Schimith, André Brito da Cunha, Cristiana Lima Dora, Mariana Appel Hort.
      Parkinson's disease (PD) is the second most common neurodegenerative disorder. The primary pathological features of PD include the presence of α-synuclein aggregates and Lewy bodies, mitochondrial dysfunction, oxidative stress, and neuroinflammation. Recently, omega-3 fatty acids (ω-3 PUFAs) have been under investigation as a preventive and/or therapeutic strategy for PD, primarily owing to their antioxidant and anti-inflammatory properties. Therefore, the objective of this study was to conduct a systematic review of the literature, focusing on studies that assessed the effects of ω-3 PUFAs in rodent models mimicking human PD. The search was performed using the terms "Parkinson's disease," "fish oil," "omega 3," "docosahexaenoic acid," and "eicosapentaenoic acid" across databases PUBMED, Web of Science, Science Direct, Scielo, and Google Scholar. Following analysis based on predefined inclusion and exclusion criteria, 39 studies were included. Considering behavioral parameters, pathological markers of the disease, quantification of ω-3 PUFAs in the brain, as well as anti-inflammatory, antioxidant, and anti-apoptotic effects, it can be observed that ω-3 PUFAs exhibit a potential neuroprotective effect in PD. In summary, this systematic review presents significant scientific evidence regarding the effects and mechanisms underlying the neuroprotective properties of ω-3 PUFAs, offering valuable insights for the development of future clinical investigations.
    Keywords:  DHA; EPA; neuroprotection; parkinsonism
    DOI:  https://doi.org/10.1111/jnc.16154
  24. Neurochem Int. 2024 Jun 20. pii: S0197-0186(24)00122-0. [Epub ahead of print] 105795
    Intermittent Fasting Induced Cerebral Ischemic Tolerance Altered Gut Microbiome and Increased Levels of Short-Chain Fatty Acids to a Beneficial Phenotype.
    Bharath Chelluboina, Tony Cho, Jin-Soo Park, Suresh L Mehta, Saivenkateshkomal Bathula, Soomin Jeong, Raghu Vemuganti.
      Preconditioning-induced cerebral ischemic tolerance is known to be a beneficial adaptation to protect the brain in an unavoidable event of stroke. We currently demonstrate that a short bout (6 weeks) of intermittent fasting (IF; 15h fast/day) induces similar ischemic tolerance to that of a longer bout (12 weeks) in adult C57BL/6 male mice subjected to transient middle cerebral artery occlusion (MCAO). In addition, the 6 weeks IF regimen induced ischemic tolerance irrespective of age (3 months or 24 months) and sex. Mice subjected to transient MCAO following IF showed improved motor function recovery (rotarod and beam walk tests) between days 1 and 14 of reperfusion and smaller infarcts (T2-MRI) on day 1 of reperfusion compared with age/sex matched ad libitum (AL) controls. Diet influences the gut microbiome composition and stroke is known to promote gut bacterial dysbiosis. We presently show that IF promotes a beneficial phenotype of gut microbiome following transient MCAO compared with AL cohort. Furthermore, post-stroke levels of short-chain fatty acids (SCFAs), which are known to be neuroprotective, are higher in the fecal samples of the IF cohort compared with the AL cohort. Thus, our studies indicate the efficacy of IF in protecting the brain after stroke, irrespective of age and sex, probably by altering gut microbiome and SCFA production.
    Keywords:  Aging; Brain damage; Dietary regimen; Gut dysbiosis; Neuroprotection; Preconditioning
    DOI:  https://doi.org/10.1016/j.neuint.2024.105795
  25. Int J Mol Sci. 2024 Jun 16. pii: 6622. [Epub ahead of print]25(12):
    The Effect of Neuronal CoQ10 Deficiency and Mitochondrial Dysfunction on a Rotenone-Induced Neuronal Cell Model of Parkinson's Disease.
    Lauren Millichap, Nadia Turton, Elisabetta Damiani, Fabio Marcheggiani, Patrick Orlando, Sonia Silvestri, Luca Tiano, Iain P Hargreaves.
      Parkinson's disease (PD) is the second most prevalent neurodegenerative disorder currently affecting the ageing population. Although the aetiology of PD has yet to be fully elucidated, environmental factors such as exposure to the naturally occurring neurotoxin rotenone has been associated with an increased risk of developing PD. Rotenone inhibits mitochondrial respiratory chain (MRC) complex I activity as well as induces dopaminergic neuronal death. The aim of the present study was to investigate the underlying mechanisms of rotenone-induced mitochondrial dysfunction and oxidative stress in an in vitro SH-SY5Y neuronal cell model of PD and to assess the ability of pre-treatment with Coenzyme Q10 (CoQ10) to ameliorate oxidative stress in this model. Spectrophotometric determination of the mitochondrial enzyme activities and fluorescence probe studies of reactive oxygen species (ROS) production was assessed. Significant inhibition of MRC complex I and II-III activities was observed, together with a significant loss of neuronal viability, CoQ10 status, and ATP synthesis. Additionally, significant increases were observed in intracellular and mitochondrial ROS production. Remarkably, CoQ10 supplementation was found to reduce ROS formation. These results have indicated mitochondrial dysfunction and increased oxidative stress in a rotenone-induced neuronal cell model of PD that was ameliorated by CoQ10 supplementation.
    Keywords:  Parkinson’s disease; antioxidant defences; coenzyme Q10; mitochondrial biogenesis; mitochondrial dysfunction; neurodegeneration; oxidative stress; pentose phosphate pathway; therapeutics
    DOI:  https://doi.org/10.3390/ijms25126622
  26. Int J Mol Sci. 2024 Jun 12. pii: 6498. [Epub ahead of print]25(12):
    Critical Role of Mitochondrial Fatty Acid Metabolism in Normal Cell Function and Pathological Conditions.
    Sergey Dikalov, Alexander Panov, Anna Dikalova.
      There is a "popular" belief that a fat-free diet is beneficial, supported by the scientific dogma indicating that high levels of fatty acids promote many pathological metabolic, cardiovascular, and neurodegenerative conditions. This dogma pressured scientists not to recognize the essential role of fatty acids in cellular metabolism and focus on the detrimental effects of fatty acids. In this work, we critically review several decades of studies and recent publications supporting the critical role of mitochondrial fatty acid metabolism in cellular homeostasis and many pathological conditions. Fatty acids are the primary fuel source and essential cell membrane building blocks from the origin of life. The essential cell membranes phospholipids were evolutionarily preserved from the earlier bacteria in human subjects. In the past century, the discovery of fatty acid metabolism was superseded by the epidemic growth of metabolic conditions and cardiovascular diseases. The association of fatty acids and pathological conditions is not due to their "harmful" effects but rather the result of impaired fatty acid metabolism and abnormal lifestyle. Mitochondrial dysfunction is linked to impaired metabolism and drives multiple pathological conditions. Despite metabolic flexibility, the loss of mitochondrial fatty acid oxidation cannot be fully compensated for by other sources of mitochondrial substrates, such as carbohydrates and amino acids, resulting in a pathogenic accumulation of long-chain fatty acids and a deficiency of medium-chain fatty acids. Despite popular belief, mitochondrial fatty acid oxidation is essential not only for energy-demanding organs such as the heart, skeletal muscle, and kidneys but also for metabolically "inactive" organs such as endothelial and epithelial cells. Recent studies indicate that the accumulation of long-chain fatty acids in specific organs and tissues support the impaired fatty acid oxidation in cell- and tissue-specific fashion. This work, therefore, provides a basis to challenge these established dogmas and articulate the need for a paradigm shift from the "pathogenic" role of fatty acids to the critical role of fatty acid oxidation. This is important to define the causative role of impaired mitochondrial fatty acid oxidation in specific pathological conditions and develop novel therapeutic approaches targeting mitochondrial fatty acid metabolism.
    Keywords:  fatty acid metabolism; mitochondria; pathological conditions; respiration
    DOI:  https://doi.org/10.3390/ijms25126498
  27. Aging Dis. 2024 May 13.
    Tryptophan Metabolism in Alzheimer's Disease with the Involvement of Microglia and Astrocyte Crosstalk and Gut-Brain Axis.
    Lushuang Xie, Qiaofeng Wu, Kelin Li, Mohammed A S Khan, Andrew Zhang, Bharati Sinha, Sihui Li, Sulie L Chang, David L Brody, Mark W Grinstaff, Shuanhu Zhou, Gil Alterovitz, Pinghua Liu, Xin Wang.
      Alzheimer's disease (AD) is an age-dependent neurodegenerative disease characterized by extracellular Amyloid Aβ peptide (Aβ) deposition and intracellular Tau protein aggregation. Glia, especially microglia and astrocytes are core participants during the progression of AD and these cells are the mediators of Aβ clearance and degradation. The microbiota-gut-brain axis (MGBA) is a complex interactive network between the gut and brain involved in neurodegeneration. MGBA affects the function of glia in the central nervous system (CNS), and microbial metabolites regulate the communication between astrocytes and microglia; however, whether such communication is part of AD pathophysiology remains unknown. One of the potential links in bilateral gut-brain communication is tryptophan (Trp) metabolism. The microbiota-originated Trp and its metabolites enter the CNS to control microglial activation, and the activated microglia subsequently affect astrocyte functions. The present review highlights the role of MGBA in AD pathology, especially the roles of Trp per se and its metabolism as a part of the gut microbiota and brain communications. We (i) discuss the roles of Trp derivatives in microglia-astrocyte crosstalk from a bioinformatics perspective, (ii) describe the role of glia polarization in the microglia-astrocyte crosstalk and AD pathology, and (iii) summarize the potential of Trp metabolism as a therapeutic target. Finally, we review the role of Trp in AD from the perspective of the gut-brain axis and microglia, as well as astrocyte crosstalk, to inspire the discovery of novel AD therapeutics.
    DOI:  https://doi.org/10.14336/AD.2024.0134
  28. Int J Tryptophan Res. 2024 ;17 11786469241262876
    The Tryptophan Metabolite Indole-3-Propionic Acid Raises Kynurenic Acid Levels in the Rat Brain In Vivo.
    Korrapati V Sathyasaikumar, Tonali Blanco-Ayala, Yiran Zheng, Lilly Schwieler, Sophie Erhardt, Maximilian Tufvesson-Alm, Burkhard Poeggeler, Robert Schwarcz.
      Alterations in the composition of the gut microbiota may be causally associated with several brain diseases. Indole-3-propionic acid (IPrA) is a tryptophan-derived metabolite, which is produced by intestinal commensal microbes, rapidly enters the circulation, and crosses the blood-brain barrier. IPrA has neuroprotective properties, which have been attributed to its antioxidant and bioenergetic effects. Here, we evaluate an alternative and/or complementary mechanism, linking IPrA to kynurenic acid (KYNA), another neuroprotective tryptophan metabolite. Adult Sprague-Dawley rats received an oral dose of IPrA (200 mg/kg), and both IPrA and KYNA were measured in plasma and frontal cortex 90 minutes, 6 or 24 hours later. IPrA and KYNA levels increased after 90 minutes and 6 hours (brain IPrA: ~56- and ~7-fold; brain KYNA: ~4- and ~3-fold, respectively). In vivo microdialysis, performed in the medial prefrontal cortex and in the striatum, revealed increased KYNA levels (~2.5-fold) following the administration of IPrA (200 mg/kg, p.o), but IPrA failed to affect extracellular KYNA when applied locally. Finally, treatment with 100 or 350 mg IPrA, provided daily to the animals in the chow for a week, resulted in several-fold increases of IPrA and KYNA levels in both plasma and brain. These results suggest that exogenously supplied IPrA may provide a novel strategy to affect the function of KYNA in the mammalian brain.
    Keywords:  Gut-brain axis; indoles; kynurenic acid; neuroprotection; tryptophan
    DOI:  https://doi.org/10.1177/11786469241262876
  29. J Lipid Res. 2024 Jun 24. pii: S0022-2275(24)00089-0. [Epub ahead of print] 100584
    A comprehensive measure of Golgi sphingolipid flux using NBD C6-Ceramide: evaluation of sphingolipid inhibitors.
    Allen H Lee, Justin M Snider, Sitapriya Moorthi, Nicolas Coant, Magali Trayssac, Daniel Canals, Christopher J Clarke, Chiara Luberto, Yusuf A Hannun.
      Measurements of sphingolipid metabolism are most accurately performed by liquid chromatography-mass spectrometry. However, this technique is expensive, not widely accessible, and without the use of specific probes, it does not provide insight into metabolic flux through the pathway. Employing the fluorescent ceramide analogue NBD-C6-ceramide as a tracer in intact cells, we developed a comprehensive HPLC-based method that simultaneously measures the main nodes of ceramide metabolism in the Golgi. Hence, by quantifying the conversion of NBD-C6-Ceramide to NBD-C6-sphingomyelin, NBD-C6-Hexosylceramides, and NBD-C6-ceramide-1-phosphate (NBD-C1P), the activities of Golgi resident enzymes sphingomyelin synthase 1, glucosylceramide synthase, and ceramide kinase (CERK) could be measured simultaneously. Importantly, the detection of NBD-C1P allowed us to quantify CERK activity in cells, a usually difficult task. By applying this method, we evaluated the specificity of commonly used sphingolipid inhibitors and discovered that PDMP, which targets glucosylceramide synthase, and fenretinide (4HPR), an inhibitor for dihydroceramide desaturase, also suppress CERK activity. This study demonstrates the benefit of an expanded analysis of ceramide metabolism in the Golgi, and it provides a qualitative and easy-to-implement method.
    Keywords:  CERK; Fenretinide; Golgi Apparatus; HPLC; NBD-Ceramide; PDMP; Sphingolipid metabolism
    DOI:  https://doi.org/10.1016/j.jlr.2024.100584
  30. Mol Cell Neurosci. 2024 Jun 21. pii: S1044-7431(24)00033-2. [Epub ahead of print] 103948
    Sphingosine kinase 2 regulates protein ubiquitination networks in neurons.
    Rocio Diaz Escarcega, Karen Murambadoro, Ricardo Valencia, Jose Felix Moruno-Manchon, Erin E Furr Stimming, Sung Yun Jung, Andrey S Tsvetkov.
      Two sphingosine kinase isoforms, sphingosine kinase 1 (SPHK1) and sphingosine kinase 2 (SPHK2), synthesize the lipid sphingosine-1-phosphate (S1P) by phosphorylating sphingosine. SPHK1 is a cytoplasmic kinase and SPHK2 is localized to the nucleus and other organelles. In the cytoplasm, the SPHK1/S1P pathway modulates autophagy and protein ubiquitination, among other processes. In the nucleus, the SPHK2/S1P pathway regulates transcription. Here, we hypothesized that the SPHK2/S1P pathway governs protein ubiquitination in neurons. We found that ectopic expression of SPHK2 increases ubiquitinated substrate levels in cultured neurons and pharmacologically inhibiting SPHK2 decreases protein ubiquitination. With mass spectrometry, we discovered that inhibiting SPHK2 affects lipid and synaptic protein networks as well as a ubiquitin-dependent protein network. Several ubiquitin-conjugating and hydrolyzing proteins such as the E3 ubiquitin-protein ligases HUWE1 and TRIP12, the E2 ubiquitin-conjugating enzyme UBE2Z, and the ubiquitin-specific proteases USP15 and USP30 were downregulated by SPHK2 inhibition. Using RNA sequencing, we found that inhibiting SPHK2 altered lipid and neuron-specific gene networks, among others. Genes that encode the corresponding proteins from the ubiquitin-dependent protein network that we discovered with mass spectrometry were not affected by inhibiting SPHK2, indicating that the SPHK2/S1P pathway regulates ubiquitination at the protein level. We also show that both SPHK2 and HUWE1 were upregulated in the striatum of a mouse model of Huntington's disease, the BACHD mice, indicating that our findings are relevant to neurodegenerative diseases. Our results identify SPHK2/S1P as a novel regulator of protein ubiquitination networks in neurons and provide a new target for developing therapies for neurodegenerative diseases.
    Keywords:  HUWE1; Huntington disease; Neurons; Sphingosine kinase 2; Sphingosine-1-phosphate; Ubiquitination
    DOI:  https://doi.org/10.1016/j.mcn.2024.103948
  31. bioRxiv. 2024 Jun 10. pii: 2024.06.09.596693. [Epub ahead of print]
    Loss of neuronal lysosomal acid lipase drives amyloid pathology in Alzheimer's disease.
    Alexandra M Barnett, Lamar Dawkins, Jian Zou, Elizabeth McNair, Viktoriya D Nikolova, Sheryl S Moy, Greg T Sutherland, Julia Stevens, Meagan Colie, Kemi Katemboh, Hope Kellner, Corina Damian, Sagan DeCastro, Ryan P Vetreno, Leon G Coleman.
      Underlying drivers of late-onset Alzheimer's disease (LOAD) pathology remain unknown. However, multiple biologically diverse risk factors share a common pathological progression. To identify convergent molecular abnormalities that drive LOAD pathogenesis we compared two common midlife risk factors for LOAD, heavy alcohol use and obesity. This revealed that disrupted lipophagy is an underlying cause of LOAD pathogenesis. Both exposures reduced lysosomal flux, with a loss of neuronal lysosomal acid lipase (LAL). This resulted in neuronal lysosomal lipid (NLL) accumulation, which opposed Aβ localization to lysosomes. Neuronal LAL loss both preceded (with aging) and promoted (targeted knockdown) Aβ pathology and cognitive deficits in AD mice. The addition of recombinant LAL ex vivo and neuronal LAL overexpression in vivo prevented amyloid increases and improved cognition. In WT mice, neuronal LAL declined with aging and correlated negatively with entorhinal Aβ. In healthy human brain, LAL also declined with age, suggesting this contributes to the age-related vulnerability for AD. In human LOAD LAL was further reduced, correlated negatively with Aβ 1-42 , and occurred with polymerase pausing at the LAL gene. Together, this finds that the loss of neuronal LAL promotes NLL accumulation to impede degradation of Aβ in neuronal lysosomes to drive AD amyloid pathology.
    Summary: Cellular and molecular drivers of late-onset Alzheimer's disease (LOAD) are unknown, though several risk factors account for the majority of disease incidence 1-5 . Though diverse in their biological natures, each of these risk exposures converge on a shared pathological progression with the accumulation of amyloid early in the disease. Human genetic and transcriptomic studies suggest a role for altered lipid metabolism 6-9 , though the mechanism has been unknown. Here, using two common midlife risk exposures for LOAD, we found that dysfunctional lipophagy caused by the loss of lysosomal acid lipase (LAL) promotes early LOAD pathogenesis. Both midlife obesity and heavy alcohol reduced neuronal LAL, causing an increase in neuronal lysosomal lipid, and a subsequent accumulation of Aβ in the extra-lysosomal cytosol. This loss of LAL preceded and promoted Aβ pathology and cognitive deficits in AD mice. The addition of recombinant LAL ex vivo and neuronal LAL overexpression in vivo prevented increases in amyloid and improved cognition. In human brain, LAL declined with age in healthy subjects, similar to rodents, showing robust losses in LOAD subjects with polymerase pausing. Together, this implicates neuronal LAL loss in LOAD pathogenesis and presents LAL as a promising diagnostic, preventative, and/or therapeutic target for AD.
    DOI:  https://doi.org/10.1101/2024.06.09.596693
  32. Int J Dev Neurosci. 2024 Jun 28.
    Ethyl pyruvate alleviates NLRP3/Caspase-1/GSDMD-mediated neuronal pyroptosis in neonatal rats with hypoxic-ischemic brain damage.
    Sha Sha, Ni Jin, Xinyi Xie, Ruiyu Zhou, Yanghao Ruan, Ying Ouyang.
      Pyroptosis is an inflammation-associated programmed cell death, and neuroinflammation is strongly associated with severe neurological deficits in neonatal hypoxic-ischemic encephalopathy (HIE). Ethyl pyruvate (EP), a known anti-inflammatory agent, has shown promise in the treatment of hypoxic-ischemic brain damage (HIBD) rats; nevertheless, the therapeutic mechanism of EP and its capacity to suppress neuronal pyroptosis in HIBD rats remain unclear. In both the neonatal Rice-Vannucci rat model and the OGD/R model, this study examined alterations in the NLRP3/Caspase-1/GSDMD classical pyroptosis pathway in hippocampal neurons during HIE and the potential inhibitory impact of ethyl pyruvate on this pathway. We used HE staining, immunofluorescence double staining, transmission electron microscopy, and western blot to demonstrate that EP effectively inhibited hippocampal neuronal pyroptosis and attenuated the activation of the NLRP3/Caspase-1/GSDMD signaling pathway in HIBD rats, which resulted in a reduction of neuroinflammation and facilitated neural recovery. The results suggest that EP may be a promising neuroprotective agent for treating HIE.
    Keywords:  NLRP3; Pyroptosis; hypoxic–ischemic encephalopathy; neuron; newborn
    DOI:  https://doi.org/10.1002/jdn.10357
  33. Epilepsy Res. 2024 Jun 13. pii: S0920-1211(24)00110-4. [Epub ahead of print]204 107395
    Efficacy and tolerability of classical and polyunsaturated fatty acids ketogenic diet in controlling paediatric refractory epilepsy - A randomized study.
    Subhasree Ray, Janak Nathan, Meena Godhia.
       OBJECTIVES: To measure and compare the efficacy and tolerability of a classical ketogenic diet (CKD) and a polyunsaturated fatty acids ketogenic diet (PUFAKD) in managing childhood refractory epilepsy. Efficacy was assessed by measuring the change in seizure frequency at 3, 6, 9, and 12 months within and between groups. The percentage reduction in seizures at <50 %, 50-90 %, >90 %, and 100 % was also measured. Tolerability was assessed and compared by recording adverse events - vomiting, nausea, lethargy, and constipation.
    METHODS: 52 children, aged 2-10 years, were randomized, 25 in the CKD group and 27 in the PUFAKD group. Fat: carbohydrate + protein ratio of 2.2:1-4:1 was maintained in both diets; the PUFAKD group only used unsaturated fats with an omega 3: omega 6 ratio of 1:2.8. Ketone levels were measured using keto-dipsticks, with 4+ and 4++ (80-160 mg/dL) being the most optimal values.
    RESULTS: A significant decrease (p=0.001) in seizures was observed (n=52), with no significant difference (p=0.537) between the two groups. The mean seizure reduction was 71.1 %, with no significant difference (p=0.488) in both groups. The mean compliance rate was 78.3 % (n=52). A statistically significant linear trend existed between a higher compliance rate and a greater reduction in seizures (p = 0.042, Z=4.039) among all children (n=52). Nausea (p=0.033) and vomiting (p=0.014) occurred more in PUFAKD than in CKD.
    CONCLUSION: No significant difference was seen in seizure reduction between the two groups. Compliance correlates with a greater seizure reduction. Despite similar seizure reduction rates, the novel PUFAKD exhibited poorer compliance and more pronounced adverse effects compared to CKD. CKD remained a superior choice over the novel PUFAKD in the management of paediatric refractory epilepsy. More controlled trials with varying PUFA compositions are recommended for long-term evaluations.
    Keywords:  Classical ketogenic diet; Ketogenic diet; Paediatric refractory epilepsy; Polyunsaturated fatty acid ketogenic diet; Seizure reduction
    DOI:  https://doi.org/10.1016/j.eplepsyres.2024.107395
  34. Neurobiol Stress. 2024 Jul;31 100646
    Omega-3 alleviates behavioral and molecular changes in a mouse model of stress-induced juvenile depression.
    Tatyana Strekalova, Daniel Radford-Smith, Isobel K Dunstan, Anna Gorlova, Evgeniy Svirin, Elisaveta Sheveleva, Alisa Burova, Sergey Morozov, Aleksey Lyundup, Gregor Berger, Daniel C Anthony, Susanne Walitza.
       Introduction: Depression is increasingly diagnosed in adolescence, necessitating specific prevention and treatment methods. However, there is a lack of animal models mimicking juvenile depression. This study explores a novel model using ultrasound (US) stress in juvenile mice.
    Methods: We employed the US stress model in one-month-old C57/BL6 mice, exposing them to alternating ultrasound frequencies (20-25 kHz and 25-45 kHz) for three weeks. These frequencies correspond to negative and neutral emotional states in rodents and can induce a depressive-like syndrome. Concurrently, mice received either an omega-3 food supplement (FS) containing eicosapentaenoic acid (EPA; 0.55 mg/kg/day) and docosahexaenoic acid (DHA; 0.55 mg/kg/day) or a vehicle. Post-stress, we evaluated anxiety- and depressive-like behaviors, blood corticosterone levels, brain expression of pro-inflammatory cytokines, and conducted metabolome analysis of brain, liver and blood plasma.
    Results: US-exposed mice treated with vehicle exhibited decreased sucrose preference, a sign of anhedonia, a key feature of depression, increased anxiety-like behavior, elevated corticosterone levels, and enhanced TNF and IL-1β gene expression in the brain. In contrast, US-FS mice did not display these changes. Omega-3 supplementation also reduced anxiety-like behavior in non-stressed mice. Metabolomic analysis revealed US-induced changes in brain energy metabolism, with FS increasing brain sphingomyelin. Liver metabolism was affected by both US and FS, while plasma metabolome changes were exclusive to FS. Brain glucose levels correlated positively with activity in anxiety tests.
    Conclusion: Chronic omega-3 intake counteracted depressive- and anxiety-like behaviors in a US model of juvenile depression in mice. These effects likely stem from the anti-inflammatory properties of the supplement, suggesting potential therapeutic applications in juvenile depression.
    Keywords:  Eicosapentaenoic and docosahexaenoic acids; Juvenile depression; Metabolome; Mice; Omega-3; Ultrasound stress
    DOI:  https://doi.org/10.1016/j.ynstr.2024.100646
  35. J Extracell Biol. 2022 Oct;1(10): e65
    Defective mitochondria-lysosomal axis enhances the release of extracellular vesicles containing mitochondrial DNA and proteins in Huntington's disease.
    Margarida Beatriz, Rita Vilaça, Sandra I Anjo, Bruno Manadas, Cristina Januário, A Cristina Rego, Carla Lopes.
      Mitochondrial and autophagy dysfunction are mechanisms proposed to be involved in the pathogenesis of several neurodegenerative diseases. Huntington's disease (HD) is a progressive neurodegenerative disorder associated with mutant Huntingtin-induced abnormalities in neuronal mitochondrial dynamics and quality control. Former studies suggest that the removal of defective mitochondria may be compromised in HD. Mitochondrial quality control (MQC) is a complex, well-orchestrated pathway that can be compromised through mitophagy dysregulation or impairment in the mitochondria-lysosomal axis. Another mitochondrial stress response is the generation of mitochondrial-derived vesicles that fuse with the endolysosomal system and form multivesicular bodies that are extruded from cells as extracellular vesicles (EVs). In this work, we aimed to study the presence of mitochondrial components in human EVs and the relation to the dysfunction of both mitochondria and the autophagy pathway. We comprehensively characterized the mitochondrial and autophagy alterations in premanifest and manifest HD carriers and performed a proteomic and genomic EVs profile. We observed that manifest HD patients exhibit mitochondrial and autophagy impairment associated with enhanced EVs release. Furthermore, we detected mitochondrial DNA and proteins in EVs released by HD cells and in neuronal-derived EVs including VDAC-1 and alpha and beta subunits of ATP synthase F1. HD-extracellular vesicles transport higher levels of mitochondrial genetic material in manifest HD patients, suggesting an alternative pathway for the secretion of reactive mitochondrial components. This study provides a novel framework connecting EVs enhanced release of mitochondrial components to mitochondrial and lysosomal dysfunction in HD.
    Keywords:  Huntington's disease; autophagy; extracellular vesicles; mitochondrial DNA; mitochondrial dysfunction; neuronal‐derived extracellular vesicles
    DOI:  https://doi.org/10.1002/jex2.65
  36. Sci Rep. 2024 06 26. 14(1): 14784
    Implications of mitochondrial membrane potential gradients on signaling and ATP production analyzed by correlative multi-parameter microscopy.
    Benjamin Gottschalk, Zhanat Koshenov, Roland Malli, Wolfgang F Graier.
      The complex architecture and biochemistry of the inner mitochondrial membrane generate ultra-structures with different phospholipid and protein compositions, shapes, characteristics, and functions. The crista junction (CJ) serves as an important barrier separating the cristae (CM) and inner boundary membranes (IBM). Thereby CJ regulates the movement of ions and ensures distinct electrical potentials across the cristae (ΔΨC) and inner boundary (ΔΨIBM) membranes. We have developed a robust and flexible approach to visualize the CJ permeability with super-resolution microscopy as a readout of local mitochondrial membrane potential (ΔΨmito) fluctuations. This method involves analyzing the distribution of TMRM fluorescence intensity in a model that is restricted to the mitochondrial geometry. We show that mitochondrial Ca2+ elevation hyperpolarizes the CM most likely caused by Ca2+ sensitive increase of mitochondrial tricarboxylic acid cycle (TCA) and subsequent oxidative phosphorylation (OXPHOS) activity in the cristae. Dynamic multi-parameter correlation measurements of spatial mitochondrial membrane potential gradients, ATP levels, and mitochondrial morphometrics revealed a CJ-based membrane potential overflow valve mechanism protecting the mitochondrial integrity during excessive cristae hyperpolarization.
    Keywords:  Correlative microscopy; Cristae junctions; Membrane potential gradient; Mitochondria; Mitochondrial membranes
    DOI:  https://doi.org/10.1038/s41598-024-65595-z
  37. Biomedicines. 2024 Jun 11. pii: 1294. [Epub ahead of print]12(6):
    Mitochondrial Dysfunction in Sporadic Amyotrophic Lateral Sclerosis Patients: Insights from High-Resolution Respirometry.
    Petra Parvanovova, Andrea Evinova, Milan Grofik, Petra Hnilicova, Zuzana Tatarkova, Monika Turcanova-Koprusakova.
      Amyotrophic lateral sclerosis is a severe neurodegenerative disease whose exact cause is still unclear. Currently, research attention is turning to the mitochondrion as a critical organelle of energy metabolism. Current knowledge is sufficient to confirm the involvement of the mitochondria in the pathophysiology of the disease, since the mitochondria are involved in many processes in the cell; however, the exact mechanism of involvement is still unclear. We used peripheral blood mononuclear cells isolated from whole fresh blood from patients with amyotrophic lateral sclerosis for measurement and matched an age- and sex-matched set of healthy subjects. The group of patients consisted of patients examined and diagnosed at the neurological clinic of the University Hospital Martin. The set of controls consisted of healthy individuals who were actively searched, and controls were selected on the basis of age and sex. The group consisted of 26 patients with sporadic forms of ALS (13 women, 13 men), diagnosed based on the definitive criteria of El Escorial. The average age of patients was 54 years, and the average age of healthy controls was 56 years. We used a high-resolution O2K respirometry method, Oxygraph-2k, to measure mitochondrial respiration. Basal respiration was lower in patients by 29.48%, pyruvate-stimulated respiration (respiratory chain complex I) was lower by 29.26%, and maximal respiratory capacity was lower by 28.15%. The decrease in succinate-stimulated respiration (respiratory chain complex II) was 26.91%. Our data confirm changes in mitochondrial respiration in ALS patients, manifested by the reduced function of complex I and complex II of the respiratory chain. These defects are severe enough to confirm this disease's hypothesized mitochondrial damage. Therefore, research interest in the future should be directed towards a deeper understanding of the involvement of mitochondria and respiratory complexes in the pathophysiology of the disease. This understanding could develop new biomarkers in diagnostics and subsequent therapeutic interventions.
    Keywords:  amyotrophic lateral sclerosis; complex I; complex II; high-resolution respirometry; mitochondria; mitochondrion dysfunction
    DOI:  https://doi.org/10.3390/biomedicines12061294
  38. J Lipid Res. 2024 Jun 21. pii: S0022-2275(24)00088-9. [Epub ahead of print] 100583
    A simplified method for preventing post-mortem alterations of brain prostanoids for true in situ level quantification.
    Derek Besch, Drew R Seeger, Brennon Schofield, Svetlana A Golovko, Meredith Parmer, Mikhail Y Golovko.
      Dramatic post-mortem prostanoid (PG) enzymatic synthesis in the brain causes a significant artifact during PG analysis. Thus, enzyme deactivation is required for an accurate in situ endogenous PG quantification. To date, the only method for preventing post-mortem brain PG increase with tissue structure preservation is fixation by head-focused microwave irradiation (MW), which is considered the gold standard method, allowing for rapid in situ heat-denaturation of enzymes. However, MW requires costly equipment that suffers in reproducibility, causing tissue loss and metabolite degradation if overheated. Our recent study indicates that PG are not synthesized in the ischemic brain unless metabolically active tissue is exposed to atmospheric O2. Based on this finding, we proposed a simple and reproducible alternative method to prevent post-mortem PG increase by slow enzyme denaturation before craniotomy. To test this approach, mice were decapitated directly into boiling saline. Brain temperature reached 100 °C after ∼140 sec during boiling, though 3 min boiling was required to completely prevent post-mortem PG synthesis, but not free arachidonic acid release. To validate this fixation method, brain basal and lipopolysaccharide (LPS)-induced PG were analyzed in unfixed, MW, and boiled tissues. Basal and LPS-induced PG levels were not different between MW and boiled brains. However, unfixed tissue showed a significant post-mortem increase in PG at basal conditions, with lesser differences upon LPS treatment compared to fixed tissue. These data indicate for the first time that boiling effectively prevents post-mortem PG alterations, allowing for a reproducible, inexpensive, and conventionally accessible tissue fixation method for PG analysis.
    Keywords:  Arachidonic acid; Brain Lipids; Cyclooxygenase; Lipidomics; Prostaglandins
    DOI:  https://doi.org/10.1016/j.jlr.2024.100583
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