bims-proned 2024-10-20 papers

bims-proned

Biomed News

on Proteostasis in neurodegeneration

Issue of 2024‒10‒20
twenty papers selected by
Verena Kohler, Umeå University

Protein aggregation and its affecting mechanisms in neurodegenerative diseases.
Bile Acids as Modulators of α-Synuclein Aggregation: Implications for Parkinson's Therapy.
Proteostasis and Its Role in Disease Development.
Unraveling the intricate link between cell death and neuroinflammation using Drosophila as a model.
Seeding Aggregation Assays in Lewy Bodies Disorders: A Narrative State-of-the-Art Review.
Time-course remodeling and pathology intervention of α-synuclein amyloid fibril by heparin and heparin-like oligosaccharides.
Disruption of PHF6 Peptide Aggregation from Tau Protein: Mechanisms of Palmatine Chloride in Preventing Early PHF6 Aggregation.
A Review on the Role of SNCA Gene in Neurodegenerative Diseases.
Neuropathology in an α-synuclein preformed fibril mouse model occurs independent of the Parkinson's disease-linked lysosomal ATP13A2 protein.
α-Synuclein aggregation decreases cortico-amygdala connectivity and impairs social behavior in mice.
Potential Mechanisms of Tunneling Nanotube Formation and Their Role in Pathology Spread in Alzheimer's Disease and Other Proteinopathies.
Effects of treadmill exercise on endoplasmic reticulum protein folding and endoplasmic reticulum-associated protein degradation pathways in APP/PS1 mice.
High-Throughput Single-Particle Characterization of Aggregation Pathways and the Effects of Inhibitors for Large (Megadalton) Protein Oligomers.
Fluorescence Lifetime-Assisted Probing of Protein Aggregation with sub-Organellar Resolution.
TDP43 aggregation at ER-exit sites impairs ER-to-Golgi transport.
The Role of Sirtuin 1 in Ageing and Neurodegenerative Disease: A Molecular Perspective.
The neurotrophic factor MANF regulates autophagy and lysosome function to promote proteostasis in Caenorhabditis elegans.
Pharmacologically increasing cGMP improves proteostasis and reduces neuropathy in mouse models of CMT1.
Deciphering the mechanisms underlying the neuroprotective potential of kaempferol: a comprehensive investigation.
Exogenous Amyloid Fibrils Can Cause Significant Upregulation of Neurodegenerative Disease Proteins.

Neurochem Int. 2024 Oct 11. pii: S0197-0186(24)00207-9. [Epub ahead of print]180 105880

Protein aggregation and its affecting mechanisms in neurodegenerative diseases.

Junyun Wu, Jianan Wu, Tao Chen, Jing Cai, Reng Ren.

  Protein aggregation serves as a critical pathological marker in a spectrum of neurodegenerative diseases (NDs), including the formation of amyloid β (Aβ) and Tau neurofibrillary tangles in Alzheimer's disease, as well as α-Synuclein (α-Syn) aggregates in Parkinson's disease, Parkinson's disease-related dementia (PDD), dementia with Lewy bodies (DLB), and multiple system atrophy (MSA). A significant proportion of patients with amyotrophic lateral sclerosis (ALS) exhibit TDP-43 aggregates. Moreover, a confluence of brain protein pathologies, such as Aβ, Tau, α-Syn, and TDP-43, has been identified in individual NDs cases, highlighting the intricate interplay among these proteins that is garnering heightened scrutiny. Importantly, protein aggregation is modulated by an array of factors, with burgeoning evidence suggesting that it frequently results from perturbations in protein homeostasis, influenced by the cellular membrane milieu, metal ion concentrations, post-translational modifications, and genetic mutations. This review delves into the pathological underpinnings of protein aggregation across various NDs and elucidates the intercommunication among disparate proteins within the same disease context. Additionally, we examine the pathogenic mechanisms by which diverse factors impinge upon protein aggregation, offering fresh perspectives for the future therapeutic intervention of NDs.

Keywords:  Familial mutations; Membrane environments; Metal ion; Neurodegenerative diseases (NDs); Post-translational modifications (PTMs); Protein aggregation

DOI:  https://doi.org/10.1016/j.neuint.2024.105880
ACS Chem Neurosci. 2024 Oct 15.

Bile Acids as Modulators of α-Synuclein Aggregation: Implications for Parkinson's Therapy.

Harpreet Kaur, Devansh Swadia, Sharmistha Sinha.

  Parkinson's disease (PD) is a neurodegenerative disorder characterized by the aggregation of α-synuclein into toxic amyloid fibrils. Recent research suggests that bile acids altered in PD may influence their aggregation. This study investigates the effects of lithocholic acid (LCA) and deoxycholic acid (DCA) on α-synuclein aggregation and toxicity. LCA significantly accelerates aggregation, reducing the lag phase by 75%, while DCA has a milder impact, decreasing the lag phase by 30%. Binding studies show that LCA interacts with the NAC region and DCA with the N-terminal region of α-synuclein. Aggregation assays and electrophoresis reveal that LCA promotes the formation of toxic, SDS-resistant oligomers more effectively than DCA. Cytotoxicity assays confirm a lower cell viability in LCA-treated samples. Additionally, combined LCA and DCA treatment results in enhanced aggregation and toxicity, indicating a synergistic effect. These findings highlight the role of bile acids in α-synuclein aggregation and PD pathogenesis, suggesting that targeting bile acid metabolism could be a therapeutic strategy for PD.

Keywords:  Parkinson’s disease.; amyloid fibril; bile acids; protein aggregation; α-synuclein

DOI:  https://doi.org/10.1021/acschemneuro.4c00459
Cell Biochem Biophys. 2024 Oct 18.

Proteostasis and Its Role in Disease Development.

Manisha Shukla, Mahesh Narayan.

  Proteostasis (protein homeostasis) refers to the general biological process that maintains the proper balance between the synthesis of proteins, their folding, trafficking, and degradation. It ensures proteins are functional, locally distributed, and appropriately folded inside cells. Genetic information enclosed in mRNA is translated into proteins. To ensure newly synthesized proteins take on the exact three-dimensional conformation, molecular chaperones assist in proper folding. Misfolded proteins can be refolded or targeted for elimination to stop aggregation. Cells utilize different degradation pathways, for instance, the ubiquitin-proteasome system, the autophagy-lysosome pathway, and the unfolded protein response, to degrade unwanted or damaged proteins. Quality control systems of the cell monitor the folding of proteins. These checkpoint mechanisms are aimed at degrading or refolding misfolded or damaged proteins. Under stress response pathways, such as heat shock response and unfolded protein response, which are triggered under conditions that perturb proteostasis, the capacity for folding is increased, and degradation pathways are activated to help cells handle stressful conditions. The deregulation of proteostasis is implicated in a variety of illnesses, comprising cancer, metabolic diseases, cardiovascular diseases, and neurological disorders. Therapeutic strategies with a deeper insight into the mechanism of proteostasis are crucial for the treatment of illnesses linked with proteostasis and to support cellular health. Thus, proteostasis is required not only for the maintenance of cellular homeostasis and function but also for proper protein function and prevention of injurious protein aggregation. In this review, we have covered the concept of proteostasis, its mechanism, and how disruptions to it can result in a number of disorders.

Keywords:  Diseases; Heat shock protein; Misfolded protein; Protein degradation pathway; Proteostasis

DOI:  https://doi.org/10.1007/s12013-024-01581-6
Front Cell Dev Biol. 2024 ;12 1479864

Unraveling the intricate link between cell death and neuroinflammation using Drosophila as a model.

Pooja Rai, Andreas Bergmann.

  Protein aggregation is a common pathological occurrence in neurodegenerative diseases. This often leads to neuroinflammation, which exacerbates the aggregation and progression of diseases like Parkinson's and Alzheimer's. Here, we focus on immune responses and neurotoxicity in a Parkinson's disease model in Drosophila. Mutations in the SNCA gene that encodes the alpha (α)-Synuclein protein have been linked to familial Parkinson's disease, disrupting autophagy regulation in neuronal cells and promoting the formation of Lewy bodies, a hallmark of Parkinson's pathology. This results in the loss of dopaminergic neurons, manifesting as movement disorders. α-Synuclein aggregation triggers innate immune responses by activating microglial cells, leading to phagocytic activity and the expression of neuroprotective antimicrobial peptides (AMPs). However, sustained AMP expression or chronic inflammation resulting from inadequate microglial phagocytosis can induce neuronal toxicity and apoptosis, leading to severe dopaminergic neuron loss. This review underscores the mechanistic connection between immune response pathways and α-Synuclein-mediated neurodegeneration using Drosophila models. Furthermore, we extensively explore factors influencing neuroinflammation and key immune signaling pathways implicated in neurodegenerative diseases, particularly Parkinson's disease. Given the limited success of traditional treatments, recent research has focused on therapies targeting inflammatory signaling pathways. Some of these approaches have shown promising results in animal models and clinical trials. We provide an overview of current therapeutic strategies showing potential in treating neurodegenerative diseases, offering new avenues for future research and treatment development.

Keywords:  Drosophila; Toll pathway; alpha (α)-Synuclein; antimicrobial peptides (AMPs); dopaminergic neurons (DNs); neuroinflammation

DOI:  https://doi.org/10.3389/fcell.2024.1479864
Int J Mol Sci. 2024 Oct 07. pii: 10783. [Epub ahead of print]25(19):

Seeding Aggregation Assays in Lewy Bodies Disorders: A Narrative State-of-the-Art Review.

Anastasia Bougea.

  Multiple system atrophy and Lewy body diseases (LBDs) such as Parkinson's disease, dementia with Lewy bodies, and Parkinson's disease with dementia, known as synucleinopathies, are defined neuropathologically by the accumulation and deposition of aberrant protein aggregates, primarily in neuronal cells. Seeding aggregation assays (SAA) have significant potential as biomarkers for early diagnosis, monitoring disease progression, and evaluating treatment efficacy for these diseases. Real-time quaking-induced conversion (RT-QuIC) and Protein Misfolding Cyclic Amplification (PMCA) assays represent two ultrasensitive protein amplification techniques that were initially tested for the field of prion disorders. Although the fundamental idea behind the creation of these two methods is very similar, their technical differences resulted in different levels of diagnostic accuracy for the identification of prion proteins, making the RT-QuIC assay the most trustworthy and effective instrument for the detection of suspected cases of LBDs and prion-like diseases.

Keywords:  Lewy body disease (LBD); alpha-synuclein; prion-like diseases; protein misfolding cyclic amplification PMCA; real-time quaking-induced conversion (RT-QuIC); seed amplification assay (SAA)

DOI:  https://doi.org/10.3390/ijms251910783
Nat Struct Mol Biol. 2024 Oct 17.

Time-course remodeling and pathology intervention of α-synuclein amyloid fibril by heparin and heparin-like oligosaccharides.

Youqi Tao, Peng Xu, Shenqing Zhang, Wei Shangguan, Guang Yang, Kaien Liu, Xiang Li, Yunpeng Sun, Qinyue Zhao, Dan Li, Biao Yu, Cong Liu.

Amyloid fibrils represent a pathological state of protein polymer that is closely associated with various neurodegenerative diseases. Polysaccharides have a prominent role in recognizing amyloid fibrils and mediating their pathogenicity. However, the mechanism underlying the amyloid-polysaccharide interaction remains elusive. We also do not know its impact on the structure and pathology of formed fibrils. Here, we used cryo-electron microscopy to analyze the atomic structures of mature α-synuclein (α-syn) fibrils upon binding with polymeric heparin and heparin-like oligosaccharides. The fibril structure, including the helical twist and conformation of α-syn, changed over time upon the binding of heparin but not oligosaccharides. The sulfation pattern and numbers of saccharide units are important for the binding. Similarly, negatively charged biopolymers typically interact with amyloid fibrils, including tau and various α-syn polymorphs, leading to alterations in their conformation. Moreover, we show that heparin-like oligosaccharides can not only block neuronal uptake and propagation of formed α-syn fibrils but also inhibit α-syn fibrillation. This work demonstrates a distinctive activity of heparin and biopolymers in remodeling amyloid fibrils and suggests the pharmaceutical potential of heparin-like oligosaccharides.

DOI: https://doi.org/10.1038/s41594-024-01407-2
ACS Chem Neurosci. 2024 Oct 15.

Disruption of PHF6 Peptide Aggregation from Tau Protein: Mechanisms of Palmatine Chloride in Preventing Early PHF6 Aggregation.

Charline Fagnen, Johanna Giovannini, Thomas Vignol, Marc Since, Marco Catto, Anne Sophie Voisin-Chiret, Jana Sopkova-de Oliveira Santos.

  The formation of neurofibrillary tangles (NFTs), composed of tau protein aggregates, is a hallmark of neurodegenerative diseases known as tauopathies, including Alzheimer's disease (AD). NFTs consist of paired helical filaments (PHFs) of tau protein with a dominant β-sheet secondary structure. Within these PHFs, the PHF6 hexapeptide (Val306-Gln-Ile-Val-Tyr-Lys311) has been commonly highlighted as a key site for tau protein nucleation. Palmatine chloride (PC) has been identified as an inhibitor of PHF6 aggregation, capable of reducing aggregation propensity at submicromolar concentrations. In pursuit of novel anti-AD drugs targeting early tau aggregation stages, we conducted an in silico study to elucidate PC's mechanism of action during PHF6 aggregation. Our observations suggest that while PHF6 can still initiate self-aggregation in the presence of PC, PC molecules subtly influence PHF6 aggregation dynamics, favoring smaller aggregates over larger complexes. The study underlined the key roles of aromatic rings in PC binding to different PHF6 aggregates by interacting through π-π stacking with the PHF6 Tyr310 side chain. The presence of aromatic rings in compounds to be able to inhibit the earlier complexation phase seems to be essential. These in silico findings lay a foundation for the design of compounds that could intervene in resolving the neurotoxicity of protein aggregates in AD.

Keywords:  Alzheimer’s disease; PHF6; aggregation mechanism; molecular dynamics; neurodegenerative disease; palmatine chloride; tau protein

DOI:  https://doi.org/10.1021/acschemneuro.4c00353
Cureus. 2024 Sep;16(9): e69450

A Review on the Role of SNCA Gene in Neurodegenerative Diseases.

Afrarahamed Jahabardeen, Nirenjen S, Narayanan J, Chitra V.

  Gene variations significantly impact the development of neurodegenerative disorders, particularly Alzheimer's disease (AD) and Parkinson's disease (PD). In AD, which is marked by amyloid-beta (Aβ) plaques and tau tangles, key genetic contributors such as amyloid beta precursor protein (APP), presenilin (PSEN1), and presenilin 2 (PSEN2) play a significant role in early-onset familial AD due to their influence on Aβ accumulation. PD, marked by dopaminergic neuron degeneration and Lewy body formation, is associated with mutations in the SNCA gene encoding alpha-synuclein (α-Syn), as well as other genes such as leucine-rich repeat kinase 2 (LRRK2), Parkin RBR E3 ubiquitin-protein ligase (PARK2), PTEN-induced kinase 1 (PINK1), and protein deglycase (DJ-1). Genome-wide association studies have identified genetic variants in apolipoprotein (APOE) and SNCA that increase disease risk. Alpha-synuclein, a protein involved in synaptic function, misfolds and aggregates into toxic forms in neurodegenerative diseases. Aggregates disrupt neuronal functions and propagate in a prion-like manner, with SNCA mutations exacerbating α-Syn aggregation and disease severity. Alpha-synuclein levels in skin, serum, cerebrospinal fluid, and plasma distinguish PD patients from healthy patients, demonstrating biomarker potential for diagnosis and therapeutic strategies. Furthermore, α-Syn's presence in neural crest-derived tissues from PD patients and melanoma patients suggests shared pathophysiological features. Ongoing research into SNCA and α-Syn is crucial for advancing diagnostics and therapeutics for neurodegenerative diseases.

Keywords:  alzhiemer’s disease; gene variations; neurodegeneration; parkinson' s disease; snca; α-synuclein

DOI:  https://doi.org/10.7759/cureus.69450
Neurobiol Dis. 2024 Oct 13. pii: S0969-9961(24)00301-2. [Epub ahead of print]202 106701

Neuropathology in an α-synuclein preformed fibril mouse model occurs independent of the Parkinson's disease-linked lysosomal ATP13A2 protein.

Caio M Massari, Dylan J Dues, Alexis Bergsma, Kayla Sipple, Maxwell Frye, Erin T Williams, Darren J Moore.

  Loss-of-function mutations in the ATP13A2 (PARK9) gene are implicated in early-onset autosomal recessive Parkinson's disease (PD) and other neurodegenerative disorders. ATP13A2 encodes a lysosomal transmembrane P5B-type ATPase that is highly expressed in brain and specifically within the substantia nigra pars compacta (SNc). Recent studies have revealed its normal role as a lysosomal polyamine transporter, although its contribution to PD-related pathology remains unclear. Cellular studies report that ATP13A2 can regulate α-synuclein (α-syn) secretion via exosomes. However, the relationship between ATP13A2 and α-syn in animal models remains inconclusive. ATP13A2 knockout (KO) mice exhibit lysosomal abnormalities and reactive astrogliosis but do not develop PD-related neuropathology. Studies manipulating α-syn levels in mice lacking ATP13A2 indicate minimal effects on pathology. The delivery of α-syn preformed fibrils (PFFs) into the mouse striatum is a well-defined model to study the development and spread of α-syn pathology. In this study we unilaterally injected wild-type (WT) and homozygous ATP13A2 KO mice with mouse α-syn PFFs in the striatum and evaluated mice for neuropathology after 6 months. The distribution, spread and extent of α-syn aggregation in multiple regions of the mouse brain was largely independent of ATP13A2 expression. The loss of nigrostriatal pathway dopaminergic neurons and their nerve terminals induced by PFFs were equivalent in WT and ATP13A2 KO mice. Reactive astrogliosis was induced equivalently by α-syn PFFs in WT and KO mice but was already significantly higher in ATP13A2 KO mice due to pre-existing reactive gliosis. We did not identify asymmetric motor disturbances, microglial activation, or axonal damage induced by α-syn PFFs in WT or KO mice. Although α-syn PFFs induce an increase in lysosomal number in the SNc in general, TH-positive dopaminergic neurons did not exhibit either increased lysosomal area or intensity, regardless of genotype. Our study evaluating the spread of α-syn pathology reveals no exacerbation of α-syn pathology, neuronal loss, astrogliosis or motor deficits in ATP13A2 KO mice, suggesting that selective lysosomal abnormalities resulting from ATP13A2 loss do not play a major role in α-syn clearance or propagation in vivo.

Keywords:  ATP13A2; Alpha-synuclein; Lysosome; Neurodegeneration; Parkinson's disease

DOI:  https://doi.org/10.1016/j.nbd.2024.106701
Neurobiol Dis. 2024 Oct 13. pii: S0969-9961(24)00302-4. [Epub ahead of print]202 106702

α-Synuclein aggregation decreases cortico-amygdala connectivity and impairs social behavior in mice.

Wei Zhou, Samuel Daniels, Vijay Singh, Marissa Menard, Martha L Escobar Galvis, Hong-Yuan Chu.

  Abnormal accumulation of insoluble α-synuclein (α-Syn) inclusions in neurons, neurites, and glial cells is the defining neuropathology of synucleinopathies, including Parkinson's disease (PD), dementia with Lewy bodies (DLB), and multiple system atrophy. Accumulation of α-Syn inclusions in the amygdala has been well-documented in post-mortem studies of PD and DLB brains, as well as preclinical animal models of these conditions. Though α-Syn pathology is closely associated with neurodegeneration, there is a poor correlation between neuronal loss in the amygdala and the clinical features of PD and DLB. Moreover, functional interaction between the cerebral cortex and the amygdala is critical to regulating emotion, motivation, and social behaviors. The cortico-amygdala functional interaction is likely to be disrupted by the development of α-Syn pathology in the brain. Thus, we hypothesize that neuronal α-Syn inclusions disrupt cortical modulation of the amygdala circuits and are sufficient to drive social behavioral deficits. In the present work, we designed a series of longitudinal studies to rigorously measure the time courses of neurodegeneration, functional impairment of cortico-amygdala connectivity, and development of amygdala-dependent social behavioral deficits to test this hypothesis. We injected α-Syn preformed fibrils (PFFs) into the dorsal striatum to induce α-Syn aggregation in the amygdala and the medial prefrontal cortex (mPFC) of C57BL6 mice of both sexes, followed by a detailed analysis of temporal development of α-Syn pathology, synaptic deficits, and neuronal loss in the amygdala, as well as behavioral deficits at 3-12 months post injections. Development of α-Syn inclusions caused losses of cortical axon terminals and cell death in the basolateral amygdala (BLA) at 6- and 12-months post injections, respectively. At a relatively early stage of 3 months post injections, the connection strength of the mPFC-BLA synapse was decreased in PFFs-injection mice compared to controls. Meanwhile, the PFFs-injected mice showed impaired social interaction behavior, which was rescued by chemogenetic stimulation of mPFC-BLA connections. Altogether, we presented a series of evidence to delineate circuit events in the amygdala associated with the accumulation of α-Syn inclusions in the mouse brain, highlighting that functional impairment of the amygdala is sufficient to cause social behavior deficits. The present work further suggests that early circuit modulation could be an effective approach to alleviate symptoms associated with α-Syn pathology, necessitating studies of functional consequences of α-Syn aggregation.

Keywords:  Amygdala; Electrophysiology; Medial prefrontal cortex; Neural circuit; Optogenetics; Parkinson's disease; Sociability; Synapse; Synucleinopathies; α-Synuclein

DOI:  https://doi.org/10.1016/j.nbd.2024.106702
Int J Mol Sci. 2024 Oct 08. pii: 10797. [Epub ahead of print]25(19):

Potential Mechanisms of Tunneling Nanotube Formation and Their Role in Pathology Spread in Alzheimer's Disease and Other Proteinopathies.

Szymon Kotarba, Marta Kozłowska, Małgorzata Scios, Kamil Saramowicz, Julia Barczuk, Zuzanna Granek, Natalia Siwecka, Wojciech Wiese, Michał Golberg, Grzegorz Galita, Grzegorz Sychowski, Ireneusz Majsterek, Wioletta Rozpędek-Kamińska.

  Alzheimer's disease (AD) is the most common type of dementia worldwide. The etiopathogenesis of this disease remains unknown. Currently, several hypotheses attempt to explain its cause, with the most well-studied being the cholinergic, beta-amyloid (Aβ), and Tau hypotheses. Lately, there has been increasing interest in the role of immunological factors and other proteins such as alpha-synuclein (α-syn) and transactive response DNA-binding protein of 43 kDa (TDP-43). Recent studies emphasize the role of tunneling nanotubes (TNTs) in the spread of pathological proteins within the brains of AD patients. TNTs are small membrane protrusions composed of F-actin that connect non-adjacent cells. Conditions such as pathogen infections, oxidative stress, inflammation, and misfolded protein accumulation lead to the formation of TNTs. These structures have been shown to transport pathological proteins such as Aβ, Tau, α-syn, and TDP-43 between central nervous system (CNS) cells, as confirmed by in vitro studies. Besides their role in spreading pathology, TNTs may also have protective functions. Neurons burdened with α-syn can transfer protein aggregates to glial cells and receive healthy mitochondria, thereby reducing cellular stress associated with α-syn accumulation. Current AD treatments focus on alleviating symptoms, and clinical trials with Aβ-lowering drugs have proven ineffective. Therefore, intensifying research on TNTs could bring scientists closer to a better understanding of AD and the development of effective therapies.

Keywords:  Alzheimer’s disease; TDP-43; Tau proteins; alpha-synuclein; beta-amyloid; dementia; etiopathogenesis; tunneling nanotubes

DOI:  https://doi.org/10.3390/ijms251910797
Heliyon. 2024 Oct 15. 10(19): e38458

Effects of treadmill exercise on endoplasmic reticulum protein folding and endoplasmic reticulum-associated protein degradation pathways in APP/PS1 mice.

Jie Xia, Jing Wang, Na Zhao, Qiang Zhang, Bo Xu.

  A hallmark of Alzheimer's disease (AD) is the disruption of protein homeostasis (proteostasis), manifested by the misfolding and aggregation of proteins. Molecular chaperones and the endoplasmic reticulum (ER)-associated protein degradation (ERAD) pathway in the ER are essential for correct protein folding and degradation of misfolded proteins respectively, thus contributing to the maintenance of proteostasis. The present study aimed to investigate whether the beneficial effects of exercise in an AD mice model is associated with changes in ER protein folding and ERAD. APP/PS1 transgenic and wild-type mice were subjected to treadmill exercise for three months. The levels of molecular chaperones, specifically protein disulfide isomerases (PDIs) and heat shock proteins (HSPs), as well as ERAD-associated molecules were analyzed in the hippocampus. The result revealed a decrease in mRNA levels of PDIA2, PDIA3, PDIA4, PDIA5, PDIA6, HSPA1B, HSPA8, HSP90B1, DNAJB2, CRYAB, and CNX, an increase in mRNA levels of HSPA5 and HSPH1, an increase in protein levels of HERPUD1, and a decrease in protein levels of VCP in APP/PS1 mice. However, following a 3-month treadmill exercise regimen, an increase in mRNA levels of PDIA2, PDIA4, PDIA6, HSPA1A, HSPA8, HSP90AB1, and DNAJB2, as well as an increase in protein levels of VCP and DERL2, and a decrease in protein levels of HERPUD1 were noted. Overall, our findings indicate that disruptions in hippocampal ER protein folding and ERAD pathways may be implicated in AD, with exercise serving as a regulator of these pathways.

Keywords:  Alzheimer's disease; Chaperones; Endoplasmic reticulum-associated protein degradation; Treadmill exercise

DOI:  https://doi.org/10.1016/j.heliyon.2024.e38458
Anal Chem. 2024 Oct 12.

High-Throughput Single-Particle Characterization of Aggregation Pathways and the Effects of Inhibitors for Large (Megadalton) Protein Oligomers.

Jacob S Jordan, Conner C Harper, Evan R Williams.

Protein aggregation is involved in many human diseases, but characterizing the sizes and shapes of intermediate oligomers (∼10-100 nm) that are important to the formation of macroscale aggregates like amyloid fibrils is a significant analytical challenge. Here, charge detection mass spectrometry (CDMS) is used to characterize individual conformational states of bovine serum albumin oligomers with up to ∼225 molecules (15 MDa). Elongated, partially folded, and globular conformational families for each oligomer can be readily distinguished based on the extent of charging. The abundances of individual conformers vary with changes in the monomer concentration or by adding aggregation inhibitors, such as SDS, heparin, or MgCl2. These results show the potential of CDMS for investigating intermediate oligomers in protein aggregation processes that are important for understanding aggregate formation and inhibition mechanisms and could accelerate formulation buffer development to prevent the aggregation of biotherapeutics.

DOI: https://doi.org/10.1021/acs.analchem.4c04669
Bio Protoc. 2024 Oct 05. 14(19): e5080

Fluorescence Lifetime-Assisted Probing of Protein Aggregation with sub-Organellar Resolution.

Karnika Gupta, Daniel C Maddison, Eduardo P Melo, Ana Rosa M da Costa, Edward Avezov.

  Protein misfolding fuels multiple neurodegenerative diseases, but existing techniques lack the resolution to pinpoint the location and physical properties of aggregates within living cells. Our protocol describes high-resolution confocal and fluorescent lifetime microscopy (Fast 3D FLIM) of an aggregation probing system. This system involves a metastable HaloTag protein (HT-aggr) labeled with P1 solvatochromic fluorophore, which can be targeted to subcellular compartments. This strategy allows to distinguish between aggregated and folded probe species, since P1 fluorophore changes its lifetime depending on the hydrophobicity of its microenvironment. The probe is not fluorescence intensity-dependent, overcoming issues related to intensity-based measurements of labeled proteins, such as control of probe quantity due to differences in expression or photobleaching of a proportion of the fluorophore population. Our approach reports on the performance of the machinery dealing with aggregation-prone substrates and thus opens doors to studying proteostasis and its role in neurodegenerative diseases. Key features • Aggregation state: Tracks aggregate formation and disaggregation with pulse-chase experiments • Sub-organellar resolution: Pinpoints and allows control of aggregate location within the cell, exceeding traditional techniques • Quantitative analysis: Measures aggregate load through image analysis • Methodology: • Metastable HaloTag variant labeling with a solvatochromic small-molecule reporter ligand • High-resolution confocal microscopy coupled with FLIM for aggregate identification and localization • Image analysis for aggregate quantification and distribution within the ER • Pulse-chase experiments to track aggregates.

Keywords:  3D-FLIM; Disaggregation; ER; FLIM; HT-aggrER

DOI:  https://doi.org/10.21769/BioProtoc.5080
Nat Commun. 2024 Oct 19. 15(1): 9026

TDP43 aggregation at ER-exit sites impairs ER-to-Golgi transport.

Hongyi Wu, Loo Chien Wang, Belle M Sow, Damien Leow, Jin Zhu, Kathryn M Gallo, Kathleen Wilsbach, Roshni Gupta, Lyle W Ostrow, Crystal J J Yeo, Radoslaw M Sobota, Rong Li.

Protein aggregation plays key roles in age-related degenerative diseases, but how different proteins coalesce to form inclusions that vary in composition, morphology, molecular dynamics and confer physiological consequences is poorly understood. Here we employ a general reporter based on mutant Hsp104 to identify proteins forming aggregates in human cells under common proteotoxic stress. We identify over 300 proteins that form different inclusions containing subsets of aggregating proteins. In particular, TDP43, implicated in Amyotrophic Lateral Sclerosis (ALS), partitions dynamically between two distinct types of aggregates: stress granule and a previously unknown non-dynamic (solid-like) inclusion at the ER exit sites (ERES). TDP43-ERES co-aggregation is induced by diverse proteotoxic stresses and observed in the motor neurons of ALS patients. Such aggregation causes retention of secretory cargos at ERES and therefore delays ER-to-Golgi transport, providing a link between TDP43 aggregation and compromised cellular function in ALS patients.

DOI: https://doi.org/10.1038/s41467-024-52706-7
Ageing Res Rev. 2024 Oct 16. pii: S1568-1637(24)00363-5. [Epub ahead of print] 102545

The Role of Sirtuin 1 in Ageing and Neurodegenerative Disease: A Molecular Perspective.

Riya Thapa, Ehssan Moglad, Muhammad Afzal, Gaurav Kumar, Asif Ahmad Bhat, Waleed Hassan Almalki, Imran Kazmi, Sami I Alzarea, Kumud Pant, Thakur Gurjeet Singh, Sachin Kumar Singh, Haider Ali.

  Sirtuin 1 (SIRT1), an NAD+-dependent deacetylase, has emerged as a key regulator of cellular processes linked to ageing and neurodegeneration. SIRT1 modulates various signalling pathways, including those involved in autophagy, oxidative stress, and mitochondrial function, which are critical in the pathogenesis of neurodegenerative diseases. This review explores the therapeutic potential of SIRT1 in several neurodegenerative disorders, including Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and Amyotrophic Lateral Sclerosis (ALS). Preclinical studies have demonstrated that SIRT1 activators, such as resveratrol, SRT1720, and SRT2104, can alleviate disease symptoms by reducing oxidative stress, enhancing autophagic flux, and promoting neuronal survival. Ongoing clinical trials are evaluating the efficacy of these SIRT1 activators, providing hope for future therapeutic strategies targeting SIRT1 in neurodegenerative diseases. This review explores the role of SIRT1 in ageing and neurodegenerative diseases, with a particular focus on its molecular mechanisms, therapeutic potential, and clinical applications.

Keywords:  Alzheimer's Disease; Cellular Homeostasis; Huntington's Disease; Neurodegenerative Diseases; Parkinson's Disease; Sirtuin 1

DOI:  https://doi.org/10.1016/j.arr.2024.102545
Proc Natl Acad Sci U S A. 2024 Oct 22. 121(43): e2403906121

The neurotrophic factor MANF regulates autophagy and lysosome function to promote proteostasis in Caenorhabditis elegans.

Shane K B Taylor, Jessica H Hartman, Bhagwati P Gupta.

  The conserved mesencephalic astrocyte-derived neurotrophic factor (MANF) is known for protecting dopaminergic neurons and functioning in various other tissues. Previously, we showed that Caenorhabditis elegans manf-1 null mutants exhibit defects such as increased endoplasmic reticulum (ER) stress, dopaminergic neurodegeneration, and abnormal protein aggregation. These findings suggest an essential role for MANF in cellular processes. However, the mechanisms by which intracellular and extracellular MANF regulate broader cellular functions remain unclear. We report a unique mechanism of action for MANF-1 that involves the transcription factor HLH-30/TFEB-mediated signaling to regulate autophagy and lysosomal function. Multiple transgenic strains overexpressing MANF-1 showed extended lifespan of animals, reduced protein aggregation, and improved neuronal survival. Using fluorescently tagged MANF-1, we observed tissue-specific localization of the protein, which was dependent on the ER retention signal. Further subcellular analysis showed that MANF-1 localizes within cells to the lysosomes and utilizes the endosomal pathway. Consistent with the lysosomal localization, our transcriptomic study of MANF-1 and analyses of autophagy regulators demonstrated that MANF-1 promotes proteostasis by regulating autophagic flux and lysosomal activity. Collectively, our findings establish MANF as a critical regulator of stress response, proteostasis, and aging.

Keywords:  ER stress; MANF-1; longevity; nematode; proteostasis

DOI:  https://doi.org/10.1073/pnas.2403906121
Cell Mol Life Sci. 2024 Oct 14. 81(1): 434

Pharmacologically increasing cGMP improves proteostasis and reduces neuropathy in mouse models of CMT1.

Seth M Moore, Joseph Gawron, Mckayla Stevens, Leandro N Marziali, Emmanuel S Buys, G Todd Milne, Maria Laura Feltri, Jordan J S VerPlank.

  Increasing cyclic GMP activates 26S proteasomes via phosphorylation by Protein Kinase G and stimulates the intracellular degradation of misfolded proteins. Therefore, agents that raise cGMP may be useful therapeutics against neurodegenerative diseases and other diseases in which protein degradation is reduced and misfolded proteins accumulate, including Charcot Marie Tooth 1A and 1B peripheral neuropathies, for which there are no treatments. Here we increased cGMP in the S63del mouse model of CMT1B by treating for three weeks with either the phosphodiesterase 5 inhibitor tadalafil, or the brain-penetrant soluble guanylyl cyclase stimulator CYR119. Both molecules activated proteasomes in the affected peripheral nerves, reduced polyubiquitinated proteins, and improved myelin thickness and nerve conduction. CYR119 increased cGMP more than tadalafil in the peripheral nerves of S63del mice and elicited greater biochemical and functional improvements. To determine whether raising cGMP could be beneficial in other neuropathies, we first showed that polyubiquitinated proteins and the disease-causing protein accumulate in the sciatic nerves of the C3 mouse model of CMT1A. Treatment of these mice with CYR119 reduced the levels of polyubiquitinated proteins and the disease-causing protein, presumably by increasing their degradation, and improved myelination, nerve conduction, and motor coordination. Thus, pharmacological agents that increase cGMP are promising treatments for CMT1 neuropathies and may be useful against other proteotoxic and neurodegenerative diseases.

Keywords:  Charcot Marie Tooth; Peripheral neuropathy; Phosphorylation; Proteasome; Protein degradation; cGMP

DOI:  https://doi.org/10.1007/s00018-024-05463-1
Naunyn Schmiedebergs Arch Pharmacol. 2024 Oct 16.

Deciphering the mechanisms underlying the neuroprotective potential of kaempferol: a comprehensive investigation.

Satyam Chaubey, Lovedeep Singh.

  Neurodegenerative disorders are characterized by neuronal degradation, dysfunction, or death within the CNS. Oxidative and inflammatory stress play crucial roles in the pathogenesis of various neurodegenerative diseases. The interplay between these stressors and dysregulated cellular signaling pathways contributes to neurodegeneration. Downregulation of NRF-2 compromises antioxidant defense, exacerbating neuronal damage, while increased TLR-4/MAPK and TLR-4/NF-κB signaling promotes neuroinflammation. Excessive ROS production by NADPH oxidase leads to oxidative damage and neuronal apoptosis. The strategies targeting NRF-2, TLR-4-mediated inflammatory stress, and NADPH oxidase activity promise to mitigate neuronal damage and halt the progression of the disease. Kaempferol is a flavonoid polyphenol antioxidant found abundantly in various fruits and vegetables, including apples, grapes, tomatoes, and broccoli. It is widely found in medicinal plants including Equisetum spp., Sophora japonica, Ginkgo biloba, and Euphorbia pekinensis (Rupr.). A substantial body of in vitro and in vivo evidences have demonstrated the neuroprotective potential of kaempferol against neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease. Kaempferol demonstrates multifaceted potential in mitigating neuroinflammation, apoptosis, and oxidative stress in different neurodegenerative diseases through the modulation of various pathways including NRF-2, NADPH oxidase, TLR-4/MAPK, and TLR-4/NF-κB. This review article was developed through a comprehensive analysis and interpretation of research published between 2009 and 2024, sourced from multiple scientific databases, including PubMed, Scopus, ScienceDirect, and Web of Science. This review aims to provide an in-depth overview of the neuroprotective effects of kaempferol, focusing on its underlying molecular mechanisms. A total of 24 research evidence were included to elucidate the molecular pathways by which kaempferol exerts its protective effects against neurodegenerative diseases.

Keywords:  Kaempferol; NADPH oxidase; NRF-2; Neuroprotection; TLR-4/MAPK; TLR-4/NF-κB

DOI:  https://doi.org/10.1007/s00210-024-03515-8
ACS Chem Neurosci. 2024 Oct 18.

Exogenous Amyloid Fibrils Can Cause Significant Upregulation of Neurodegenerative Disease Proteins.

Xihua Liu, Wenzhe Jia, Yapeng Fang, Yiping Cao.

  Neurodegenerative diseases, such as Alzheimer's disease and Parkinson's disease, are associated with the formation of amyloid fibrils. In familial cases, the mutant causative genes accentuate disease progression through overexpression or misfolding of amyloidogenic proteins. Besides, considerable amyloidosis cases arise from external factors, but their origin and mechanisms are not yet fully understood. Herein, we found that amyloid fibrils generated from egg and milk proteins, in addition to their nutritional effects to intestinal cells, can selectively reduce the viability of nervous cells as well as pancreatic islet cells. In contrast, soy protein amyloid fibrils lacked cytotoxicity to the aforementioned cells. This protein source and cell type-dependent cytotoxicity are demonstrated to be associated with the significant upregulation of amyloidogenic proteins. The finding was also confirmed by the vein injection of beta-lactoglobulin fibrils to mice, exhibiting the pronounced upregulations of amyloid beta1-42 (Aβ1-42) and islet amyloid polypeptide in vivo. The study therefore provides insight into the health implications of exogenous amyloid fibrils.

Keywords:  Aβ; amyloid fibrils; cytotoxicity; food proteins; neurodegenerative diseases

DOI:  https://doi.org/10.1021/acschemneuro.4c00483