bims-midhyp 2023-10-15 papers

bims-midhyp

Biomed News

on Mitochondrial dysfunction and hypoxia

Issue of 2023‒10‒15
twenty-one papers selected by
Alia Ablieh, Universität Heidelberg

Hypoxia-Induced Signaling in Gut and Liver Pathobiology.
The functional significance of mitochondrial respiratory chain supercomplexes.
Crosstalk between mitochondrial biogenesis and mitophagy to maintain mitochondrial homeostasis.
Cell-Type-Specific Mitochondrial Quality Control in the Brain: A Plausible Mechanism of Neurodegeneration.
PPTC7 maintains mitochondrial protein content by suppressing receptor-mediated mitophagy.
Sestrin2 protects against hypoxic nerve injury by regulating mitophagy through SESN2/AMPK pathway.
The Pulmonary Endothelial Glycocalyx Modifications in Glypican 1 Knockout Mice Do Not Affect Lung Endothelial Function in Physiological Conditions.
SIRT1 and HSP90α feed-forward circuit safeguards chromosome segregation integrity in diffuse large B cell lymphomas.
The multifaceted role of mitochondria in HSC fate decisions: energy and beyond.
The complexity of nicotinamide adenine dinucleotide (NAD), hypoxic, and aryl hydrocarbon receptor cell signaling in chronic kidney disease.
Ecological network analysis reveals cancer-dependent chaperone-client interaction structure and robustness.
Mitochondrial Oxidative Stress Is the General Reason for Apoptosis Induced by Different-Valence Heavy Metals in Cells and Mitochondria.
METTL3-Mediated RNA m6A Modification Regulates the Angiogenic Behaviors of Retinal Endothelial Cells by Methylating MMP2 and TIE2.
Positive regulation of oxidative phosphorylation by nuclear myosin 1 protects cells from metabolic reprogramming and tumorigenesis in mice.
Increased Ca2 + transport across the mitochondria-associated membranes by Mfn2 inhibiting endoplasmic reticulum stress in ischemia/reperfusion kidney injury.
The Pro-Oncogenic Protein IF1 Promotes Proliferation of Anoxic Cancer Cells during Re-Oxygenation.
Non-chemical signalling between mitochondria.
Human brain microvascular endothelial cells release different types of P-glycoprotein-containing extracellular vesicles upon exposure to doxorubicin.
Beyond the Scale: Investigating Adiponectin, ICAM-1, and VCAM-1 as Metabolic Markers in Obese Adolescents with Metabolic Syndrome.
NARFL deficiency caused mitochondrial dysfunction in lung cancer cells by HIF-1α-DNMT1 axis.
Multi-Omics Profiling of Human Endothelial Cells from the Coronary Artery and Internal Thoracic Artery Reveals Molecular but Not Functional Heterogeneity.

Annu Rev Pathol. 2023 Oct 13.

Hypoxia-Induced Signaling in Gut and Liver Pathobiology.

Sumeet Solanki, Yatrik M Shah.

Oxygen (O2) is essential for cellular metabolism and biochemical reactions. When the demand for O2 exceeds the supply, hypoxia occurs. Hypoxia-inducible factors (HIFs) are essential to activate adaptive and survival responses following hypoxic stress. In the gut (intestines) and liver, oxygen gradients or physiologic hypoxia are necessary to maintain normal homeostasis. While physiologic hypoxia is beneficial and aids in normal functions, pathological hypoxia is harmful as it exacerbates inflammatory responses and tissue dysfunction and is a hallmark of many cancers. In this review, we discuss the role of gut and liver hypoxia-induced signaling, primarily focusing on HIFs, in the physiology and pathobiology of gut and liver diseases. Additionally, we examine the function of HIFs in various cell types during gut and liver diseases, beyond intestinal epithelial and hepatocyte HIFs. This review highlights the importance of understanding hypoxia-induced signaling in the pathogenesis of gut and liver diseases and emphasizes the potential of HIFs as therapeutic targets. Expected final online publication date for the Annual Review of Pathology: Mechanisms of Disease, Volume 19 is January 2024. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

DOI: https://doi.org/10.1146/annurev-pathmechdis-051122-094743
EMBO Rep. 2023 Oct 12. e57092

The functional significance of mitochondrial respiratory chain supercomplexes.

Andreas Kohler, Antoni Barrientos, Flavia Fontanesi, Martin Ott.

  The mitochondrial respiratory chain (MRC) is a key energy transducer in eukaryotic cells. Four respiratory chain complexes cooperate in the transfer of electrons derived from various metabolic pathways to molecular oxygen, thereby establishing an electrochemical gradient over the inner mitochondrial membrane that powers ATP synthesis. This electron transport relies on mobile electron carries that functionally connect the complexes. While the individual complexes can operate independently, they are in situ organized into large assemblies termed respiratory supercomplexes. Recent structural and functional studies have provided some answers to the question of whether the supercomplex organization confers an advantage for cellular energy conversion. However, the jury is still out, regarding the universality of these claims. In this review, we discuss the current knowledge on the functional significance of MRC supercomplexes, highlight experimental limitations, and suggest potential new strategies to overcome these obstacles.

Keywords:  Mitochondria; bioenergetics; electron transfer; respiratory chain; supercomplexes

DOI:  https://doi.org/10.15252/embr.202357092
J Biomed Sci. 2023 Oct 12. 30(1): 86

Crosstalk between mitochondrial biogenesis and mitophagy to maintain mitochondrial homeostasis.

Lei Liu, Yanjun Li, Guo Chen, Quan Chen.

  Mitochondrial mass and quality are tightly regulated by two essential and opposing mechanisms, mitochondrial biogenesis (mitobiogenesis) and mitophagy, in response to cellular energy needs and other cellular and environmental cues. Great strides have been made to uncover key regulators of these complex processes. Emerging evidence has shown that there exists a tight coordination between mitophagy and mitobiogenesis, and their defects may cause many human diseases. In this review, we will first summarize the recent advances made in the discovery of molecular regulations of mitobiogenesis and mitophagy and then focus on the mechanism and signaling pathways involved in the simultaneous regulation of mitobiogenesis and mitophagy in the response of tissue or cultured cells to energy needs, stress, or pathophysiological conditions. Further studies of the crosstalk of these two opposing processes at the molecular level will provide a better understanding of how the cell maintains optimal cellular fitness and function under physiological and pathophysiological conditions, which holds promise for fighting aging and aging-related diseases.

Keywords:  Aging; Aging-related diseases; Mitochondrial biogenesis; Mitochondrial quality; Mitophagy; Mitophagy receptors

DOI:  https://doi.org/10.1186/s12929-023-00975-7
Int J Mol Sci. 2023 Sep 22. pii: 14421. [Epub ahead of print]24(19):

Cell-Type-Specific Mitochondrial Quality Control in the Brain: A Plausible Mechanism of Neurodegeneration.

Hariprasath Ragupathy, Manasvi Vukku, Sandeep Kumar Barodia.

  Neurodegeneration is an age-dependent progressive phenomenon with no defined cause. Aging is the main risk factor for neurodegenerative diseases. During aging, activated microglia undergo phenotypic alterations that can lead to neuroinflammation, which is a well-accepted event in the pathogenesis of neurodegenerative diseases. Several common mechanisms are shared by genetically or pathologically distinct neurodegenerative diseases, such as excitotoxicity, mitochondrial deficits and oxidative stress, protein misfolding and translational dysfunction, autophagy and microglia activation. Progressive loss of the neuronal population due to increased oxidative stress leads to neurodegenerative diseases, mostly due to the accumulation of dysfunctional mitochondria. Mitochondrial dysfunction and excessive neuroinflammatory responses are both sufficient to induce pathology in age-dependent neurodegeneration. Therefore, mitochondrial quality control is a key determinant for the health and survival of neuronal cells in the brain. Research has been primarily focused to demonstrate the significance of neuronal mitochondrial health, despite the important contributions of non-neuronal cells that constitute a significant portion of the brain volume. Moreover, mitochondrial morphology and function are distinctly diverse in different tissues; however, little is known about their molecular diversity among cell types. Mitochondrial dynamics and quality in different cell types markedly decide the fate of overall brain health; therefore, it is not justifiable to overlook non-neuronal cells and their significant and active contribution in facilitating overall neuronal health. In this review article, we aim to discuss the mitochondrial quality control of different cell types in the brain and how important and remarkable the diversity and highly synchronized connecting property of non-neuronal cells are in keeping the neurons healthy to control neurodegeneration.

Keywords:  astrocytes; microglia; mitochondria; neurons; oligodendrocytes; oxidative stress

DOI:  https://doi.org/10.3390/ijms241914421
Nat Commun. 2023 Oct 13. 14(1): 6431

PPTC7 maintains mitochondrial protein content by suppressing receptor-mediated mitophagy.

Natalie M Niemi, Lia R Serrano, Laura K Muehlbauer, Catherine E Balnis, Lianjie Wei, Andrew J Smith, Keri-Lyn Kozul, Merima Forny, Olivia M Connor, Edrees H Rashan, Evgenia Shishkova, Kathryn L Schueler, Mark P Keller, Alan D Attie, Jonathan R Friedman, Julia K Pagan, Joshua J Coon, David J Pagliarini.

PPTC7 is a resident mitochondrial phosphatase essential for maintaining proper mitochondrial content and function. Newborn mice lacking Pptc7 exhibit aberrant mitochondrial protein phosphorylation, suffer from a range of metabolic defects, and fail to survive beyond one day after birth. Using an inducible knockout model, we reveal that loss of Pptc7 in adult mice causes marked reduction in mitochondrial mass and metabolic capacity with elevated hepatic triglyceride accumulation. Pptc7 knockout animals exhibit increased expression of the mitophagy receptors BNIP3 and NIX, and Pptc7-/- mouse embryonic fibroblasts (MEFs) display a major increase in mitophagy that is reversed upon deletion of these receptors. Our phosphoproteomics analyses reveal a common set of elevated phosphosites between perinatal tissues, adult liver, and MEFs, including multiple sites on BNIP3 and NIX, and our molecular studies demonstrate that PPTC7 can directly interact with and dephosphorylate these proteins. These data suggest that Pptc7 deletion causes mitochondrial dysfunction via dysregulation of several metabolic pathways and that PPTC7 may directly regulate mitophagy receptor function or stability. Overall, our work reveals a significant role for PPTC7 in the mitophagic response and furthers the growing notion that management of mitochondrial protein phosphorylation is essential for ensuring proper organelle content and function.

DOI: https://doi.org/10.1038/s41467-023-42069-w
Front Mol Biosci. 2023 ;10 1266243

Sestrin2 protects against hypoxic nerve injury by regulating mitophagy through SESN2/AMPK pathway.

Cunyao Pan, Chongyi Ai, Lanlan Liang, Baoyi Zhang, Qionglin Li, Lingling Pu, Zirou Wang, Weili Liu, Zhaoli Chen, Hui Liu, Xinxing Wang.

  Hypoxia induced by high altitude can lead to severe neurological dysfunction. Mitophagy is known to play a crucial role in hypoxic nerve injury. However, the regulatory mechanism of mitophagy during this injury remains unclear. Recent studies have highlighted the role of Sestrin2 (SESN2), an evolutionarily conserved stress-inducible protein against acute hypoxia. Our study demonstrated that hypoxia treatment increased SESN2 expression and activated mitophagy in PC12 cells. Furthermore, the knock-out of Sesn2 gene led to a significant increase in mitochondrial membrane potential and ATP concentrations, which protected the PC12 cells from hypoxic injury. Although the AMPK/mTOR pathway was significantly altered under hypoxia, it does not seem to participate in mitophagy regulation. Instead, our data suggest that the mitophagy receptor FUNDC1 plays a vital role in hypoxia-induced mitophagy. Moreover, SESN2 may function through synergistic regulation with other pathways, such as SESN2/AMPK, to mediate cellular adaptation to hypoxia, including the regulation of mitophagy in neuron cells. Therefore, SESN2 plays a critical role in regulating neural cell response to hypoxia. These findings offer valuable insights into the underlying molecular mechanisms governing the regulation of mitophagy under hypoxia and further highlight the potential of SESN2 as a promising therapeutic target for hypoxic nerve injury.

Keywords:  AMPK; FUNDC1; SESN2; hypoxia; mitophagy; neurological dysfunction

DOI:  https://doi.org/10.3389/fmolb.2023.1266243
Int J Mol Sci. 2023 Sep 26. pii: 14568. [Epub ahead of print]24(19):

The Pulmonary Endothelial Glycocalyx Modifications in Glypican 1 Knockout Mice Do Not Affect Lung Endothelial Function in Physiological Conditions.

Lakshmi N R Thota, Joaquin E Lopez Rosales, Ivan Placencia, Evgeny A Zemskov, Paola Tonino, Ashley N Michael, Stephen M Black, Andreia Z Chignalia.

  The endothelial glycocalyx is a dynamic signaling surface layer that is involved in the maintenance of cellular homeostasis. The glycocalyx has a very diverse composition, with glycoproteins, proteoglycans, and glycosaminoglycans interacting with each other to form a mesh-like structure. Due to its highly interactive nature, little is known about the relative contribution of each glycocalyx constituent to its overall function. Investigating the individual roles of the glycocalyx components to cellular functions and system physiology is challenging, as the genetic manipulation of animals that target specific glycocalyx components may result in the development of a modified glycocalyx. Thus, it is crucial that genetically modified animal models for glycocalyx components are characterized and validated before the development of mechanistic studies. Among the glycocalyx components, glypican 1, which acts through eNOS-dependent mechanisms, has recently emerged as a player in cardiovascular diseases. Whether glypican 1 regulates eNOS in physiological conditions is unclear. Herein, we assessed how the deletion of glypican 1 affects the development of the pulmonary endothelial glycocalyx and the impact on eNOS activity and endothelial function. Male and female 5-9-week-old wild-type and glypican 1 knockout mice were used. Transmission electron microscopy, immunofluorescence, and immunoblotting assessed the glycocalyx structure and composition. eNOS activation and content were assessed by immunoblotting; nitric oxide production was assessed by the Griess reaction. The pulmonary phenotype was evaluated by histological signs of lung injury, in vivo measurement of lung mechanics, and pulmonary ventilation. Glypican 1 knockout mice showed a modified glycocalyx with increased glycocalyx thickness and heparan sulfate content and decreased expression of syndecan 4. These alterations were associated with decreased phosphorylation of eNOS at S1177. The production of nitric oxides was not affected by the deletion of glypican 1, and the endothelial barrier was preserved in glypican 1 knockout mice. Pulmonary compliance was decreased, and pulmonary ventilation was unaltered in glypican 1 knockout mice. Collectively, these data indicate that the deletion of glypican 1 may result in the modification of the glycocalyx without affecting basal lung endothelial function, validating this mouse model as a tool for mechanistic studies that investigate the role of glypican 1 in lung endothelial function.

Keywords:  eNOS; endothelial; glycocalyx; glypican 1; heparan sulfate; lung

DOI:  https://doi.org/10.3390/ijms241914568
Cell Death Dis. 2023 10 11. 14(10): 667

SIRT1 and HSP90α feed-forward circuit safeguards chromosome segregation integrity in diffuse large B cell lymphomas.

Emilia Białopiotrowicz-Data, Monika Noyszewska-Kania, Ewa Jabłońska, Tomasz Sewastianik, Dorota Komar, Sonia Dębek, Filip Garbicz, Magdalena Wojtas, Maciej Szydłowski, Anna Polak, Patryk Górniak, Przemysław Juszczyński.

Diffuse large B-cell lymphoma (DLBCL) is the most common aggressive non-Hodgkin lymphoma in adults, exhibiting highly heterogenous clinical behavior and complex molecular background. In addition to the genetic complexity, different DLBCL subsets exhibit phenotypic features independent of the genetic background. For example, a subset of DLBCLs is distinguished by increased oxidative phosphorylation and unique transcriptional features, including overexpression of certain mitochondrial genes and a molecular chaperone, heat shock protein HSP90α (termed "OxPhos" DLBCLs). In this study, we identified a feed-forward pathogenetic circuit linking HSP90α and SIRT1 in OxPhos DLBCLs. The expression of the inducible HSP90α isoform remains under SIRT1-mediated regulation. SIRT1 knockdown or chemical inhibition reduced HSP90α expression in a mechanism involving HSF1 transcription factor, whereas HSP90 inhibition reduced SIRT1 protein stability, indicating that HSP90 chaperones SIRT1. SIRT1-HSP90α interaction in DLBCL cells was confirmed by co-immunoprecipitation and proximity ligation assay (PLA). The number of SIRT1-HSP90α complexes in PLA was significantly higher in OxPhos- dependent than -independent cells. Importantly, SIRT1-HSP90α interactions in OxPhos DLBCLs markedly increased in mitosis, suggesting a specific role of the complex during this cell cycle phase. RNAi-mediated and chemical inhibition of SIRT1 and/or HSP90 significantly increased the number of cells with chromosome segregation errors (multipolar spindle formation, anaphase bridges and lagging chromosomes). Finally, chemical SIRT1 inhibitors induced dose-dependent cytotoxicity in OxPhos-dependent DLBCL cell lines and synergized with the HSP90 inhibitor. Taken together, our findings define a new OxPhos-DLBCL-specific pathogenetic loop involving SIRT1 and HSP90α that regulates chromosome dynamics during mitosis and may be exploited therapeutically.

DOI: https://doi.org/10.1038/s41419-023-06186-0
Exp Hematol. 2023 Oct 11. pii: S0301-472X(23)01736-8. [Epub ahead of print]

The multifaceted role of mitochondria in HSC fate decisions: energy and beyond.

Marie-Dominique Filippi.

Hematopoietic stem cells (HSCs) have the properties to self-renew and/or differentiate into all mature blood cell lineages. The fate decisions to generate progeny that retain stemness properties or that commit to differentiation is a fundamental process to maintain tissue homeostasis and must be tightly regulated in order to prevent HSC overgrowth or exhaustion. HSC fate decisions are inherently coupled to cell division. The transition from quiescence to activation is accompanied by major metabolic and mitochondrial changes that are important for cell cycle entry for balanced decisions between self-renewal and differentiation. In this review, we discuss the current understanding of the role of mitochondrial metabolism in HSC transition from quiescence to activation and fate decisions.

DOI: https://doi.org/10.1016/j.exphem.2023.10.001
J Transl Med. 2023 Oct 09. 21(1): 706

The complexity of nicotinamide adenine dinucleotide (NAD), hypoxic, and aryl hydrocarbon receptor cell signaling in chronic kidney disease.

Colleen S Curran, Jeffrey B Kopp.

  Early-stage detection of chronic kidney diseases (CKD) is important to treatment that may slow and occasionally halt CKD progression. CKD of diverse etiologies share similar histologic patterns of glomerulosclerosis, tubular atrophy, and interstitial fibrosis. Macro-vascular disease and micro-vascular disease promote tissue ischemia, contributing to injury. Tissue ischemia promotes hypoxia, and this in turn activates the hypoxia-inducible transcription factors (HIFs). HIF-1α and HIF-2α, share a dimer partner, HIF-1β, with the aryl hydrocarbon receptor (AHR) and are each activated in CKD and associated with kidney cellular nicotinamide adenine dinucleotide (NAD) depletion. The Preiss-Handler, salvage, and de novo pathways regulate NAD biosynthesis and gap-junctions regulate NAD cellular retention. In the Preiss-Handler pathway, niacin forms NAD. Niacin also exhibits crosstalk with HIF and AHR cell signals in the regulation of insulin sensitivity, which is a complication in CKD. Dysregulated enzyme activity in the NAD de novo pathway increases the levels of circulating tryptophan metabolites that activate AHR, resulting in poly-ADP ribose polymerase activation, thrombosis, endothelial dysfunction, and immunosuppression. Therapeutically, metabolites from the NAD salvage pathway increase NAD production and subsequent sirtuin deacetylase activity, resulting in reduced activation of retinoic acid-inducible gene I, p53, NF-κB and SMAD2 but increased activation of FOXO1, PGC-1α, and DNA methyltransferase-1. These post-translational responses may also be initiated through non-coding RNAs (ncRNAs), which are additionally altered in CKD. Nanoparticles traverse biological systems and can penetrate almost all tissues as disease biomarkers and drug delivery carriers. Targeted delivery of non-coding RNAs or NAD metabolites with nanoparticles may enable the development of more effective diagnostics and therapies to treat CKD.

Keywords:  Aryl hydrocarbon receptor (AHR); Fibrosis; Glycolysis; Hypoxia-inducible factor (HIF); Inflammation; NF-κB; Nicotinamide adenine dinucleotide (NAD); Poly-ADP ribose polymerase (PARP); Sirtuin

DOI:  https://doi.org/10.1186/s12967-023-04584-8
Nat Commun. 2023 10 07. 14(1): 6277

Ecological network analysis reveals cancer-dependent chaperone-client interaction structure and robustness.

Geut Galai, Xie He, Barak Rotblat, Shai Pilosof.

Cancer cells alter the expression levels of metabolic enzymes to fuel proliferation. The mitochondrion is a central hub of metabolic reprogramming, where chaperones service hundreds of clients, forming chaperone-client interaction networks. How network structure affects its robustness to chaperone targeting is key to developing cancer-specific drug therapy. However, few studies have assessed how structure and robustness vary across different cancer tissues. Here, using ecological network analysis, we reveal a non-random, hierarchical pattern whereby the cancer type modulates the chaperones' ability to realize their potential client interactions. Despite the low similarity between the chaperone-client interaction networks, we highly accurately predict links in one cancer type based on another. Moreover, we identify groups of chaperones that interact with similar clients. Simulations of network robustness show that this group structure affects cancer-specific response to chaperone removal. Our results open the door for new hypotheses regarding the ecology and evolution of chaperone-client interaction networks and can inform cancer-specific drug development strategies.

DOI: https://doi.org/10.1038/s41467-023-41906-2
Int J Mol Sci. 2023 Sep 22. pii: 14459. [Epub ahead of print]24(19):

Mitochondrial Oxidative Stress Is the General Reason for Apoptosis Induced by Different-Valence Heavy Metals in Cells and Mitochondria.

Sergey M Korotkov.

  This review analyzes the causes and consequences of apoptosis resulting from oxidative stress that occurs in mitochondria and cells exposed to the toxic effects of different-valence heavy metals (Ag+, Tl+, Hg2+, Cd2+, Pb2+, Al3+, Ga3+, In3+, As3+, Sb3+, Cr6+, and U6+). The problems of the relationship between the integration of these toxic metals into molecular mechanisms with the subsequent development of pathophysiological processes and the appearance of diseases caused by the accumulation of these metals in the body are also addressed in this review. Such apoptosis is characterized by a reduction in cell viability, the activation of caspase-3 and caspase-9, the expression of pro-apoptotic genes (Bax and Bcl-2), and the activation of protein kinases (ERK, JNK, p53, and p38) by mitogens. Moreover, the oxidative stress manifests as the mitochondrial permeability transition pore (MPTP) opening, mitochondrial swelling, an increase in the production of reactive oxygen species (ROS) and H2O2, lipid peroxidation, cytochrome c release, a decline in the inner mitochondrial membrane potential (ΔΨmito), a decrease in ATP synthesis, and reduced glutathione and oxygen consumption as well as cytoplasm and matrix calcium overload due to Ca2+ release from the endoplasmic reticulum (ER). The apoptosis and respiratory dysfunction induced by these metals are discussed regarding their interaction with cellular and mitochondrial thiol groups and Fe2+ metabolism disturbance. Similarities and differences in the toxic effects of Tl+ from those of other heavy metals under review are discussed. Similarities may be due to the increase in the cytoplasmic calcium concentration induced by Tl+ and these metals. One difference discussed is the failure to decrease Tl+ toxicity through metallothionein-dependent mechanisms. Another difference could be the decrease in reduced glutathione in the matrix due to the reversible oxidation of Tl+ to Tl3+ near the centers of ROS generation in the respiratory chain. The latter may explain why thallium toxicity to humans turned out to be higher than the toxicity of mercury, lead, cadmium, copper, and zinc.

Keywords:  apoptosis; heavy metals; mitochondrial permeability transition pore; oxidative stress; toxic mechanisms

DOI:  https://doi.org/10.3390/ijms241914459
Invest Ophthalmol Vis Sci. 2023 Oct 03. 64(13): 18

METTL3-Mediated RNA m6A Modification Regulates the Angiogenic Behaviors of Retinal Endothelial Cells by Methylating MMP2 and TIE2.

Yong Lin, Guangying Luo, Qi Liu, Rusen Yang, Peter Sol Reinach, Dongsheng Yan.

Purpose: N6-methyladenosine (m6A) is a commonly occurring modification of mRNAs, catalyzed by a complex containing methyltransferase like 3 (METTL3). Our research aims to explore how METTL3-dependent m6A modification affects the functions of retinal endothelial cells (RECs).Methods: An oxygen-induced retinopathy (OIR) mouse model was established, and RECs were isolated using magnetic beads method. Human retinal microvascular endothelial cells (HRMECs) were treated with normoxia (21% O2) or hypoxia (1% O2). Dot blot assay determined m6A modification levels. Quantitative RT-PCR and Western blot detected the mRNA and protein expression levels of the target candidates, respectively. Genes were knocked down by small interfering RNA transfection. Matrigel-based angiogenesis and transwell assays evaluated the abilities of endothelial tube formation and migration, respectively. Methylated RNA immunoprecipitation-qPCR determined the levels of m6A modification in the target genes.
Results: The m6A modification levels were significantly upregulated in the retinas and RECs of OIR mice. Exposure to hypoxia significantly elevated both METTL3 expression and m6A modification levels in HRMECs. METTL3 knockdown curtailed endothelial tube formation and migration in vitro under both normoxic and hypoxic conditions. Concurrently, this knockdown in HRMECs resulted in reduced m6A modification levels of MMP2 and TIE2 transcripts, subsequently leading to a decrease in their respective protein expressions. Notably, knockdown of MMP2 and TIE2 also markedly inhibited the angiogenic activities of HRMECs.
Conclusions: METTL3-mediated m6A modification promotes the angiogenic behaviors of RECs by targeting MMP2 and TIE2, suggesting its significance in retinal angiogenesis and METTL3 as a potential therapeutic target.

DOI: https://doi.org/10.1167/iovs.64.13.18
Nat Commun. 2023 Oct 10. 14(1): 6328

Positive regulation of oxidative phosphorylation by nuclear myosin 1 protects cells from metabolic reprogramming and tumorigenesis in mice.

Tomas Venit, Oscar Sapkota, Wael Said Abdrabou, Palanikumar Loganathan, Renu Pasricha, Syed Raza Mahmood, Nadine Hosny El Said, Shimaa Sherif, Sneha Thomas, Salah Abdelrazig, Shady Amin, Davide Bedognetti, Youssef Idaghdour, Mazin Magzoub, Piergiorgio Percipalle.

Metabolic reprogramming is one of the hallmarks of tumorigenesis. Here, we show that nuclear myosin 1 (NM1) serves as a key regulator of cellular metabolism. NM1 directly affects mitochondrial oxidative phosphorylation (OXPHOS) by regulating mitochondrial transcription factors TFAM and PGC1α, and its deletion leads to underdeveloped mitochondria inner cristae and mitochondrial redistribution within the cell. These changes are associated with reduced OXPHOS gene expression, decreased mitochondrial DNA copy number, and deregulated mitochondrial dynamics, which lead to metabolic reprogramming of NM1 KO cells from OXPHOS to aerobic glycolysis.This, in turn, is associated with a metabolomic profile typical for cancer cells, namely increased amino acid-, fatty acid-, and sugar metabolism, and increased glucose uptake, lactate production, and intracellular acidity. NM1 KO cells form solid tumors in a mouse model, suggesting that the metabolic switch towards aerobic glycolysis provides a sufficient carcinogenic signal. We suggest that NM1 plays a role as a tumor suppressor and that NM1 depletion may contribute to the Warburg effect at the onset of tumorigenesis.

DOI: https://doi.org/10.1038/s41467-023-42093-w
Sci Rep. 2023 Oct 12. 13(1): 17257

Increased Ca2 + transport across the mitochondria-associated membranes by Mfn2 inhibiting endoplasmic reticulum stress in ischemia/reperfusion kidney injury.

Shun Wang, Xiaohong Sang, Suhua Li, Wenjun Yang, Shihan Wang, Haixia Chen, Chen Lu.

Renal ischemia/reperfusion (I/R) injury, which leads to acute kidney injury (AKI), is a major cause of morbidity and mortality in a variety of clinical situations. This study aimed to investigate the protective role of Mfn2 during renal I/R injury. Overexpression of Mfn2 in NRK-52E rat renal tubular epithelial cells and rats, then we constructed hypoxia reoxygenation (H/R) cells and I/R rat model. Apoptosis, ROS, ATP, Ca2+ levels in cells and rats, as well as renal tissue and functional injury in rats were detected respectively. Endoplasmic reticulum (ER) stress was further examined in cells and rats. The morphological changes of mitochondria-associated ER membranes (MAMs) were also detected. Mfn2 expression is reduced in H/R-treated NRK-52E cells and renal tissue of I/R rats. At the cellular level, overexpression of Mfn2 promoted cell proliferation, inhibited cell apoptosis, attenuated mitochondrial damage and Ca2+ overload, and ER stress. In addition, Mfn2 also restored the MAMs structure. In vivo experiments found that overexpression of Mfn2 could improve renal function and alleviate tissue injury. Concomitant with elevated Mfn2 expression in the kidney, reduced renal cell apoptosis, restored mitochondrial function, and reduced calcium overload. Finally, ER stress in rat kidney tissue was alleviated after overexpression of Mfn2. These results reveal that Mfn2 contributes to ER stress, mitochondrial function, and cell death in I/R injury, which provides a novel therapeutic target for AKI.

DOI: https://doi.org/10.1038/s41598-023-44538-0
Int J Mol Sci. 2023 Sep 27. pii: 14624. [Epub ahead of print]24(19):

The Pro-Oncogenic Protein IF1 Promotes Proliferation of Anoxic Cancer Cells during Re-Oxygenation.

Riccardo Righetti, Silvia Grillini, Valentina Del Dotto, Anna Costanzini, Francesca Liuzzi, Claudia Zanna, Gianluca Sgarbi, Giancarlo Solaini, Alessandra Baracca.

  Cancer cells overexpress IF1, the endogenous protein that inhibits the hydrolytic activity of ATP synthase when mitochondrial membrane potential (ΔμH+) falls, as in ischemia. Other roles have been ascribed to IF1, but the associated molecular mechanisms are still under debate. We investigated the ability of IF1 to promote survival and proliferation in osteosarcoma and colon carcinoma cells exposed to conditions mimicking ischemia and reperfusion, as occurs in vivo, particularly in solid tumors. IF1-silenced and parental cells were exposed to the FCCP uncoupler to collapse ΔμH+ and the bioenergetics of cell models were validated. All the uncoupled cells preserved mitochondrial mass, but the implemented mechanisms differed in IF1-expressing and IF1-silenced cells. Indeed, the membrane potential collapse and the energy charge preservation allowed an increase in both mitophagy and mitochondrial biogenesis in IF1-expressing cells only. Interestingly, the presence of IF1 also conferred a proliferative advantage to cells highly dependent on oxidative phosphorylation when the uncoupler was washed out, mimicking cell re-oxygenation. Overall, our results indicate that IF1, by allowing energy preservation and promoting mitochondrial renewal, can favor proliferation of anoxic cells and tumor growth. Therefore, hindering the action of IF1 may be promising for the therapy of tumors that rely on oxidative phosphorylation for energy production.

Keywords:  143B osteosarcoma cells; ATP synthase; HCT116 colon carcinoma cells; anoxia; autophagy; biogenesis; metabolism; mitochondria; mitophagy; oxidative phosphorylation

DOI:  https://doi.org/10.3390/ijms241914624
Front Physiol. 2023 ;14 1268075

Non-chemical signalling between mitochondria.

Rhys R Mould, Ifigeneia Kalampouka, E Louise Thomas, Geoffrey W Guy, Alistair V W Nunn, Jimmy D Bell.

  A wide variety of studies have reported some form of non-chemical or non-aqueous communication between physically isolated organisms, eliciting changes in cellular proliferation, morphology, and/or metabolism. The sources and mechanisms of such signalling pathways are still unknown, but have been postulated to involve vibration, volatile transmission, or light through the phenomenon of ultraweak photon emission. Here, we report non-chemical communication between isolated mitochondria from MCF7 (cancer) and MCF10A (non-cancer) cell lines. We found that mitochondria in one cuvette stressed by an electron transport chain inhibitor, antimycin, alters the respiration of mitochondria in an adjacent, but chemically and physically separate cuvette, significantly decreasing the rate of oxygen consumption compared to a control (p = <0.0001 in MCF7 and MCF10A mitochondria). Moreover, the changes in O2-consumption were dependent on the origin of mitochondria (cancer vs. non-cancer) as well as the presence of "ambient" light. Our results support the existence of non-chemical signalling between isolated mitochondria. The experimental design suggests that the non-chemical communication is light-based, although further work is needed to fully elucidate its nature.

Keywords:  biophoton; bystander effect; metabolic photon emission; non-chemical signalling; radicals; ultraweak luminescence; ultraweak photon emission

DOI:  https://doi.org/10.3389/fphys.2023.1268075
Toxicol Appl Pharmacol. 2023 Oct 09. pii: S0041-008X(23)00351-4. [Epub ahead of print] 116712

Human brain microvascular endothelial cells release different types of P-glycoprotein-containing extracellular vesicles upon exposure to doxorubicin.

Felix Osten, Wolfgang Löscher, Birthe Gericke.

  In the brain, the efflux transporter P-glycoprotein (Pgp) is predominantly located on the luminal membrane of microvascular endothelial cells (BMECs) that form the blood-brain barrier. In addition, Pgp is localized in intracellular organelles involved in Pgp traffic and cycling and, by the release of extracellular vesicles (EVs), in intercellular Pgp transfer to cells with low Pgp expression. We recently described that drug exposure of a human BMEC line (hCMEC/D3) induces the release of Pgp-EGFP-containing EVs; however, the nature of the Pgp-enriched vesicles was not characterized. The two main categories of EVs are exosomes and microvesicles, which differ in origin, size, and molecular cargo. In the present study, we performed similar experiments with hCMEC/D3 cells in the absence and presence of doxorubicin and isolated and characterized the EVs released by the cells during the experiments by differential ultracentrifugation with/without subsequent sucrose gradient fractionation of EV pellets, proteomic profiling, EV size analysis, and confocal fluorescence microscopy. Using cocultures of hCMEC/D3 wildtype cells and cells transduced with MDR1-EGFP or monocultures of hCMEC/D3-MDR1-EGFP cells, we found release of both Pgp-enriched exosomes and microvesicles but analysis of the exosomal marker protein Rab7 indicated that doxorubicin increased particularly the release of exosomes. Transfer experiments with isolated EVs demonstrated EV endocytosis by recipient cells. EV release from BMECs in response to anticancer drugs such as doxorubicin likely serves different functions, including non-genetic intercellular transfer of a resistance phenotype to neighboring BMECs and a mechanism of drug extrusion that contributes to brain protection against potentially toxic chemotherapeutic drugs.

Keywords:  Blood-brain barrier; Drug resistance; Efflux transporter; Exosomes; Microvesicles

DOI:  https://doi.org/10.1016/j.taap.2023.116712
J Obes. 2023 ;2023 4574042

Beyond the Scale: Investigating Adiponectin, ICAM-1, and VCAM-1 as Metabolic Markers in Obese Adolescents with Metabolic Syndrome.

Nur Aisiyah Widjaja, Leonardo Alexander Caesar, Suhasta Nova, Eva Ardianah.

Background: Adiponectin acts to prevent vascular dysfunction due to obesity by inhibiting ICAM-1 and VCAM-1 expressions.Objective: We investigate adiponectin ICAM-1, VCAM-1, and metabolic syndrome (MetS) in obese adolescents.
Methods: A cross-sectional study with healthy obese adolescents aged 13 to 18 years was conducted from October 2019 to January 2020. Statistical analysis conducted was a test of normality and homogeneity tests, ANOVA/Kruskal-Wallis, independent sample T-test/Mann-Whitney U test, and Spearman correlation and determined as significant if p value <0.05.
Results: 125 obese adolescents were recruited. 42 (33.6%) were obese with MetS (we grouped as MetS) and 83 (66.4%) subjects without MetS (non-MetS group). VCAM-1 was significantly higher on boys with MetS compared to girls with MetS, and even girls with MetS had lower levels of VCAM-1 than boys with non-MetS. ICAM-1 was significantly higher in boys with low-level HDL-c (p < 0.05) and correlated weakly with HDL-c, while adiponectin levels were significantly lower in girls with central obesity and hypertriglyceridemia. Path analysis showed that triglyceride had a direct effect on ICAM-1 but not VCAM-1 in both obese boys and girls. Adiponectin had a negative direct effect on ICAM-1 and VCAM-1 in girls. However, on boys, diastole blood pressure had a negative direct effect, which might be the role of sex hormones indirectly.
Conclusion: VCAM-1 was significantly higher in boys than girls, which showed that boys had a higher risk of atherosclerosis. ICAM-1 showed no significant difference in both gender and metabolic states. Adiponectin showed a protective effect by lowering ICAM-1 and VCAM-1 directly on girls.

DOI: https://doi.org/10.1155/2023/4574042
Sci Rep. 2023 10 11. 13(1): 17176

NARFL deficiency caused mitochondrial dysfunction in lung cancer cells by HIF-1α-DNMT1 axis.

Hongzhou Liu, Xueqin Wu, Tianrong Yang, Chen Wang, Fei Huang, Ying Xu, Jie Peng.

NARFL was reported to be a component of cytosolic iron-sulfur cluster assembly pathway and a causative gene of the diffused pulmonary arteriovenous malformations (dPAVMs). NARFL knockout dramatically impaired mitochondrial integrity in mice, which might promote mitochondrial dysfunction and lead to worse survival rate of lung cancer. However, the underlying molecular mechanism of NARFL deficiency in non-small cell lung cancer (NSCLC) is unknown. Knockdown assay was performed in A549 and H1299 cells. The protein levels of HIF-1α and DNMT1 were measured, and then Complex I activity, mtDNA copy numbers and mRNA levels of mtND genes were determined. Cisplatin resistance and cell proliferation were conducted using CCK8 assay. Cell migration and invasion were detected using wound heal assay and transwell assay. Survival analysis of lung cancer patients and KM plotter database were used for evaluating the potential value of NARFL deficiency. NARFL protein was expressed in two cell lines and knockdown assay significantly reduced its levels. Knockdown NARFL increased the protein levels of HIF-1α and DNMT1, and downregulated the mRNA levels of ND genes, mitochondrial Complex I activity, mtDNA copy number, and ATP levels. The mitochondrial dysfunction caused by NARFL deficiency were ameliorated by siHIF-1α and DNMT1 inhibitor. Knockdown NARFL increased the drug resistance and cell migration, and siHIF-1α reversed this effect. Moreover, NSCLC patients with NARFL deficiency had a poor survival rate using a tissue array and KM plotter database, and it would be a target for cancer prognosis and treatment. NARFL deficiency caused dysregulation of energy metabolism in lung cancer cells via HIF-1α-DNMT1 axis, which promoted drug resistance and cell migration. It provided a potential target for treatment and prognosis of lung cancer.

DOI: https://doi.org/10.1038/s41598-023-44418-7
Int J Mol Sci. 2023 Oct 09. pii: 15032. [Epub ahead of print]24(19):

Multi-Omics Profiling of Human Endothelial Cells from the Coronary Artery and Internal Thoracic Artery Reveals Molecular but Not Functional Heterogeneity.

Alexey Frolov, Arseniy Lobov, Marsel Kabilov, Bozhana Zainullina, Alexey Tupikin, Daria Shishkova, Victoria Markova, Anna Sinitskaya, Evgeny Grigoriev, Yulia Markova, Anton Kutikhin.

  Major adverse cardiovascular events occurring upon coronary artery bypass graft surgery are typically accompanied by endothelial dysfunction. Total arterial revascularisation, which employs both left and right internal thoracic arteries instead of the saphenous vein to create a bypass, is associated with better mid- and long-term outcomes. We suggested that molecular profiles of human coronary artery endothelial cells (HCAECs) and human internal mammary artery endothelial cells (HITAECs) are coherent in terms of transcriptomic and proteomic signatures, which were then investigated by RNA sequencing and ultra-high performance liquid chromatography-mass spectrometry, respectively. Both HCAECs and HITAECs overexpressed molecules responsible for the synthesis of extracellular matrix (ECM) components, basement membrane assembly, cell-ECM adhesion, organisation of intercellular junctions, and secretion of extracellular vesicles. HCAECs were characterised by higher enrichment with molecular signatures of basement membrane construction, collagen biosynthesis and folding, and formation of intercellular junctions, whilst HITAECs were notable for augmented pro-inflammatory signaling, intensive synthesis of proteins and nitrogen compounds, and enhanced ribosome biogenesis. Despite HCAECs and HITAECs showing a certain degree of molecular heterogeneity, no specific markers at the protein level have been identified. Coherence of differentially expressed molecular categories in HCAECs and HITAECs suggests synergistic interactions between these ECs in a bypass surgery scenario.

Keywords:  RNA sequencing; coronary artery; coronary artery bypass graft surgery; endothelial cells; endothelial heterogeneity; global gene expression; internal thoracic artery; multi-omics; proteomic profiling; transcriptome

DOI:  https://doi.org/10.3390/ijms241915032