bims-proned 2024-05-19 papers

bims-proned

Biomed News

on Proteostasis in neurodegeneration

Issue of 2024–05–19
twelve papers selected by
Verena Kohler, Umeå University

Curcumin Inhibits α-Synuclein Aggregation by Acting on Liquid-Liquid Phase Transition.
Amyloid β accelerates age-related proteome-wide protein insolubility.
Molecular mechanism of α-synuclein aggregation on lipid membranes revealed.
Rpt5-Derived Analogs Stimulate Human Proteasome Activity in Cells and Degrade Proteins Forming Toxic Aggregates in Age-Related Diseases.
Amyloid Accelerator Polyphosphate Implicated as the Mystery Density in α-Synuclein Fibrils.
The Enigma of Tau Protein Aggregation: Mechanistic Insights and Future Challenges.
ROF-2 as an Aggregation-Induced Emission (AIE) Probe for Multi-Target Amyloid Detection and Screening of Amyloid Inhibitors.
Viral overexpression of human alpha-synuclein in mouse substantia nigra dopamine neurons results in hyperdopaminergia but no neurodegeneration.
Interplay of Proteostasis Capacity and Protein Aggregation: Implications for Cellular Function and Disease.
The Role of Liquid-Liquid Phase Separation in the Accumulation of Pathological Proteins: New Perspectives on the Mechanism of Neurodegenerative Diseases.
Synthesis and evaluation of catecholamine derivatives as amyloid-beta aggregation inhibitors.
Polyglutamine-mediated ribotoxicity disrupts proteostasis and stress responses in Huntington's disease.

Foods. 2024 Apr 23. pii: 1287. [Epub ahead of print]13(9):

Curcumin Inhibits α-Synuclein Aggregation by Acting on Liquid-Liquid Phase Transition.

Jian-Feng Li, Zi-Qun Jiang, Sen Cao, Meng-Xin Zhang, Li-Hui Wang, Jun Liu, Yan-Hua Lu, Hong-Yan Wang, Xiao-Jing Hong, Zhi-Guo Wang, Jun-Ping Liu.

  Parkinson's disease (PD), the second most common neurodegenerative disorder, is linked to α-synuclein (α-Syn) aggregation. Despite no specific drug being available for its treatment, curcumin, from the spice turmeric, shows promise. However, its application in PD is limited by a lack of understanding of its anti-amyloidogenic mechanisms. In this study, we first reconstructed the liquid-liquid phase separation (LLPS) of α-Syn in vitro under different conditions, which may be an initial step in entraining the pathogenic aggregation. Subsequently, we evaluated the effects of curcumin on the formation of droplets, oligomers, and aggregated fibers during the LLPS of α-synuclein, as well as its impact on the toxicity of aggregated α-synuclein to cultured cells. Importantly, we found that curcumin can inhibit amyloid formation by inhibiting the occurrence of LLPS and the subsequent formation of oligomers of α-Syn in the early stages of aggregation. Finally, the molecular dynamic simulations of interactions between α-Syn decamer fibrils and curcumin showed that van der Waal's interactions make the largest contribution to the anti-aggregation effect of curcumin. These results may help to clarify the mechanism by which curcumin inhibits the formation of α-Syn aggregates during the development of PD.

Keywords:  Parkinson’s disease; anti-aggregation; curcumin; molecular dynamics; α-synuclein

DOI:  https://doi.org/10.3390/foods13091287
Geroscience. 2024 May 16.

Amyloid β accelerates age-related proteome-wide protein insolubility.

Edward Anderton, Manish Chamoli, Dipa Bhaumik, Christina D King, Xueshu Xie, Anna Foulger, Julie K Andersen, Birgit Schilling, Gordon J Lithgow.

  Loss of proteostasis is a highly conserved feature of aging across model organisms and results in the accumulation of insoluble protein aggregates. Protein insolubility is also a unifying feature of major age-related neurodegenerative diseases, including Alzheimer's Disease (AD), in which hundreds of insoluble proteins associate with aggregated amyloid beta (Aβ) in senile plaques. Despite the connection between aging and AD risk, therapeutic approaches to date have overlooked aging-driven generalized protein insolubility as a contributing factor. However, proteins that become insoluble during aging in model organisms are capable of accelerating Aβ aggregation in vitro and lifespan in vivo. Here, using an unbiased proteomics approach, we questioned the relationship between Aβ and age-related protein insolubility. Specifically, we uncovered that Aβ expression drives proteome-wide protein insolubility in C. elegans, even in young animals, and this insoluble proteome is highly similar to the insoluble proteome driven by normal aging, this vulnerable sub-proteome we term the core insoluble proteome (CIP). We show that the CIP is enriched with proteins that modify Aβ toxicity in vivo, suggesting the possibility of a vicious feedforward cycle in the context of AD. Importantly, using human genome-wide association studies (GWAS), we show that the CIP is replete with biological processes implicated not only in neurodegenerative diseases but also across a broad array of chronic, age-related diseases (CARDs). This provides suggestive evidence that age-related loss of proteostasis could play a role in general CARD risk. Finally, we show that the geroprotective, gut-derived metabolite, Urolithin A, relieves Aβ toxicity, supporting its use in clinical trials for dementia and age-related diseases.

Keywords:  Amyloid β; Protein insolubility; Proteostasis

DOI:  https://doi.org/10.1007/s11357-024-01169-1
Chem Sci. 2024 May 15. 15(19): 7229-7242

Molecular mechanism of α-synuclein aggregation on lipid membranes revealed.

Alexander J Dear, Xiangyu Teng, Sarah R Ball, Joshua Lewin, Robert I Horne, Daniel Clow, Alisdair Stevenson, Natasha Harper, Kim Yahya, Xiaoting Yang, Suzanne C Brewerton, John Thomson, Thomas C T Michaels, Sara Linse, Tuomas P J Knowles, Johnny Habchi, Georg Meisl.

The central hallmark of Parkinson's disease pathology is the aggregation of the α-synuclein protein, which, in its healthy form, is associated with lipid membranes. Purified monomeric α-synuclein is relatively stable in vitro, but its aggregation can be triggered by the presence of lipid vesicles. Despite this central importance of lipids in the context of α-synuclein aggregation, their detailed mechanistic role in this process has not been established to date. Here, we use chemical kinetics to develop a mechanistic model that is able to globally describe the aggregation behaviour of α-synuclein in the presence of DMPS lipid vesicles, across a range of lipid and protein concentrations. Through the application of our kinetic model to experimental data, we find that the reaction is a co-aggregation process involving both protein and lipids and that lipids promote aggregation as much by enabling fibril elongation as by enabling their initial formation. Moreover, we find that the primary nucleation of lipid-protein co-aggregates takes place not on the surface of lipid vesicles in bulk solution but at the air-water and/or plate interfaces, where lipids and proteins are likely adsorbed. Our model forms the basis for mechanistic insights, also in other lipid-protein co-aggregation systems, which will be crucial in the rational design of drugs that inhibit aggregate formation and act at the key points in the α-synuclein aggregation cascade.

DOI: https://doi.org/10.1039/d3sc05661a
Int J Mol Sci. 2024 Apr 25. pii: 4663. [Epub ahead of print]25(9):

Rpt5-Derived Analogs Stimulate Human Proteasome Activity in Cells and Degrade Proteins Forming Toxic Aggregates in Age-Related Diseases.

Katarzyna Cekała, Karolina Trepczyk, Julia Witkowska, Elżbieta Jankowska, Ewa Wieczerzak.

  Aging and age-related diseases are associated with a decline in the capacity of protein turnover. Intrinsically disordered proteins, as well as proteins misfolded and oxidatively damaged, prone to aggregation, are preferentially digested by the ubiquitin-independent proteasome system (UIPS), a major component of which is the 20S proteasome. Therefore, boosting 20S activity constitutes a promising strategy to counteract a decrease in total proteasome activity during aging. One way to enhance the proteolytic removal of unwanted proteins appears to be the use of peptide-based activators of the 20S. In this study, we synthesized a series of peptides and peptidomimetics based on the C-terminus of the Rpt5 subunit of the 19S regulatory particle. Some of them efficiently stimulated human 20S proteasome activity. The attachment of the cell-penetrating peptide TAT allowed them to penetrate the cell membrane and stimulate proteasome activity in HEK293T cells, which was demonstrated using a cell-permeable substrate of the proteasome, TAS3. Furthermore, the best activator enhanced the degradation of aggregation-prone α-synuclein and Tau-441. The obtained compounds may therefore have the potential to compensate for the unbalanced proteostasis found in aging and age-related diseases.

Keywords:  activator; age-related diseases; aging; proteasome

DOI:  https://doi.org/10.3390/ijms25094663
bioRxiv. 2024 May 02. pii: 2024.05.01.592011. [Epub ahead of print]

Amyloid Accelerator Polyphosphate Implicated as the Mystery Density in α-Synuclein Fibrils.

Philipp Huettemann, Pavithra Mahadevan, Justine Lempart, Eric Tse, Budheswar Dehury, Brian F P Edwards, Daniel R Southworth, Bikash R Sahoo, Ursula Jakob.

Aberrant aggregation of α-Synuclein is the pathological hallmark of a set of neurodegenerative diseases termed synucleinopathies. Recent advances in cryo-electron microscopy have led to the structural determination of the first synucleinopathy-derived α-Synuclein fibrils, which contain a non-proteinaceous, "mystery density" at the core of the protofilaments, hypothesized to be highly negatively charged. Guided by previous studies that demonstrated that polyphosphate (polyP), a universally conserved polyanion, significantly accelerates α-Synuclein fibril formation, we conducted blind docking and molecular dynamics simulation experiments to model the polyP binding site in α-Synuclein fibrils. Here we demonstrate that our models uniformly place polyP into the lysine-rich pocket, which coordinates the mystery density in patient-derived fibrils. Subsequent in vitro studies and experiments in cells revealed that substitution of the two critical lysine residues K43 and K45 leads to a loss of all previously reported effects of polyP binding on α-Synuclein, including stimulation of fibril formation, change in filament conformation and stability as well as alleviation of cytotoxicity. In summary, our study demonstrates that polyP fits the unknown electron density present in in vivo α-Synuclein fibrils and suggests that polyP exerts its functions by neutralizing charge repulsion between neighboring lysine residues.

DOI: https://doi.org/10.1101/2024.05.01.592011
Int J Mol Sci. 2024 May 02. pii: 4969. [Epub ahead of print]25(9):

The Enigma of Tau Protein Aggregation: Mechanistic Insights and Future Challenges.

Huiting Zheng, Huimin Sun, Qixu Cai, Hwan-Ching Tai.

  Tau protein misfolding and aggregation are pathological hallmarks of Alzheimer's disease and over twenty neurodegenerative disorders. However, the molecular mechanisms of tau aggregation in vivo remain incompletely understood. There are two types of tau aggregates in the brain: soluble aggregates (oligomers and protofibrils) and insoluble filaments (fibrils). Compared to filamentous aggregates, soluble aggregates are more toxic and exhibit prion-like transmission, providing seeds for templated misfolding. Curiously, in its native state, tau is a highly soluble, heat-stable protein that does not form fibrils by itself, not even when hyperphosphorylated. In vitro studies have found that negatively charged molecules such as heparin, RNA, or arachidonic acid are generally required to induce tau aggregation. Two recent breakthroughs have provided new insights into tau aggregation mechanisms. First, as an intrinsically disordered protein, tau is found to undergo liquid-liquid phase separation (LLPS) both in vitro and inside cells. Second, cryo-electron microscopy has revealed diverse fibrillar tau conformations associated with different neurodegenerative disorders. Nonetheless, only the fibrillar core is structurally resolved, and the remainder of the protein appears as a "fuzzy coat". From this review, it appears that further studies are required (1) to clarify the role of LLPS in tau aggregation; (2) to unveil the structural features of soluble tau aggregates; (3) to understand the involvement of fuzzy coat regions in oligomer and fibril formation.

Keywords:  Alzheimer’s disease; amyloids; fibrils; oligomers; phase separation; protein misfolding

DOI:  https://doi.org/10.3390/ijms25094969
Small. 2024 May 15. e2400879

ROF-2 as an Aggregation-Induced Emission (AIE) Probe for Multi-Target Amyloid Detection and Screening of Amyloid Inhibitors.

Yijing Tang, Dong Zhang, Jie Zheng.

  Misfolding and aggregation of amyloid peptides into β-structure-rich fibrils represent pivotal pathological features in various neurodegenerative diseases, including Alzheimer's disease (AD), type II diabetes (T2D), and medullary thyroid carcinoma (MTC). The development of effective amyloid detectors and inhibitors for probing and preventing amyloid aggregation is crucial for diagnosing and treating debilitating diseases, yet it poses significant challenges. Here, an aggregation-induced emission (AIE) molecule of ROF2 with multifaceted functionalities as an amyloid probe and a screening tool for amyloid inhibitors using different biophysical, cellular, and worm assays, are reported. As an amyloid probe, ROF2 outperformed ThT, demonstrating its superior sensing capability in monitoring, detecting, and distinguishing amyloid aggregates of different sequences (Amyloid-β, human islet amyloid polypeptide, or human calcitonin) and sizes (monomers, oligomers, or fibrils). More importantly, the utilization of ROF2 as a screening molecule to identify and repurpose cardiovascular drugs as amyloid inhibitors is introduced. These drugs exhibit potent amyloid inhibition properties, effectively preventing amyloid aggregation and reducing amyloid-induced cytotoxicity both in cells and nematode. The findings present a novel strategy to discovery AIE-based amyloid probes and to be used to repurpose amyloid inhibitors, expanding diagnostic and therapeutic options for neurodegenerative diseases while addressing vascular congestion and amyloid aggregation risks.

Keywords:  amyloid peptide; biomarker sensor; drug screening; neurodegenerative disease; protein aggregation

DOI:  https://doi.org/10.1002/smll.202400879
bioRxiv. 2024 May 05. pii: 2024.05.03.592188. [Epub ahead of print]

Viral overexpression of human alpha-synuclein in mouse substantia nigra dopamine neurons results in hyperdopaminergia but no neurodegeneration.

Sofia Ines Garcia Moreno, Fabian Limani, Iina Ludwig, Catherine Gilbert, Christian Pifl, Thomas S Hnasko, Thomas Steinkellner.

Loss of select neuronal populations such as midbrain dopamine (DA) neurons is a pathological hallmark of Parkinson's disease (PD). The small neuronal protein α-synuclein has been related both genetically and neuropathologically to PD, yet how it contributes to selective vulnerability remains elusive. Here, we describe the generation of a novel adeno-associated viral vector (AAV) for Cre-dependent overexpression of wild-type human α-synuclein. Our strategy allows us to restrict α-synuclein to select neuronal populations and hence investigate the cell-autonomous effects of elevated α-synuclein in genetically-defined cell types. Since DA neurons in the substantia nigra pars compacta (SNc) are particularly vulnerable in PD, we investigated in more detail the effects of increased α-synuclein in these cells. AAV-mediated overexpression of wildtype human α-synuclein in SNc DA neurons increased the levels of α-synuclein within these cells and augmented phosphorylation of α-synuclein at serine-129, which is considered a pathological feature of PD and other synucleinopathies. However, despite abundant α-synuclein overexpression and hyperphosphorylation we did not observe any DA neurodegeneration up to 90 days post virus infusion. In contrast, we noticed that overexpression of α-synuclein resulted in increased locomotor activity and elevated striatal DA levels suggesting that α-synuclein enhanced dopaminergic activity. We therefore conclude that cell-autonomous effects of elevated α-synuclein are not sufficient to trigger acute DA neurodegeneration.

DOI: https://doi.org/10.1101/2024.05.03.592188
J Mol Biol. 2024 May 15. pii: S0022-2836(24)00210-9. [Epub ahead of print] 168615

Interplay of Proteostasis Capacity and Protein Aggregation: Implications for Cellular Function and Disease.

Mark S Hipp, F Ulrich Hartl.

  Eukaryotic cells are equipped with an intricate proteostasis network (PN), comprising nearly 3000 components dedicated to preserving proteome integrity and sustaining protein homeostasis. This protective system is particularly important under conditions of external and intrinsic cell stress, where inherently dynamic proteins may unfold and lose functionality. A decline in proteostasis capacity is associated with the aging process, resulting in a reduced folding efficiency of newly synthesized proteins and a deficit in the cellular capacity to degrade misfolded proteins. A critical consequence of PN insufficiency is the accumulation of cytotoxic protein aggregates that underlie various age-related neurodegenerative conditions and other pathologies. By interfering with specific proteostasis components, toxic aggregates place an excessive burden on the PN's ability to maintain proteome integrity. This initiates a feed-forward loop, wherein the generation of misfolded and aggregated proteins ultimately leads to proteostasis collapse and cellular demise.

Keywords:  neurodegenerative disease; protein aggregation; protein folding; proteostasis

DOI:  https://doi.org/10.1016/j.jmb.2024.168615
Aging Dis. 2024 May 08.

The Role of Liquid-Liquid Phase Separation in the Accumulation of Pathological Proteins: New Perspectives on the Mechanism of Neurodegenerative Diseases.

Xingyu Lu, Jiongtong Lu, Shengnan Li, Sifan Feng, Yan Wang, Lili Cui.

It is widely accepted that living organisms form highly dynamic membrane-less organelles (MLOS) with various functions through phase separation, and the indispensable role that phase separation plays in the mechanisms of normal physiological functions and pathogenesis is gradually becoming clearer. Pathological aggregates, regarded as hallmarks of neurodegenerative diseases, have been revealed to be closely related to aberrant phase separation. Specific proteins are assembled into condensates and transform into insoluble inclusions through aberrant phase separation, contributing to the development of diseases. In this review, we present an overview of the progress of phase separation research, involving its biological mechanisms and the status of research in neurodegenerative diseases, focusing on five main disease-specific proteins, tau, TDP-43, FUS, α-Syn and HTT, and how exactly these proteins reside within dynamic liquid-like compartments and thus turn into solid deposits. Further studies will yield new perspectives for understanding the aggregation mechanisms and potential therapeutic strategies, and future research directions are anticipated.

DOI: https://doi.org/10.14336/AD.2024.0209
Bioorg Med Chem Lett. 2024 May 11. pii: S0960-894X(24)00190-2. [Epub ahead of print]107 129788

Synthesis and evaluation of catecholamine derivatives as amyloid-beta aggregation inhibitors.

Fusheng Xu, Yuya Takiguchi, Koki Makabe, Hiroyuki Konno.

  Effectively inhibition of amyloid β (Aβ) aggregation is considered an important method for treatment of the Alzheimer's disease. Herein, inspired by the ability of trans-clovamide to effectively inhibit Aβ aggregation, we synthesized a series of structurally related catecholamine derivatives and tested them as Aβ aggregation inhibitors using the Thioflavin T assay. The results show that they demonstrated a higher inhibitory rate against Aβ aggregation. Furthermore, these compounds exhibited high water solubilities and low cytotoxicities. Additionally, transmission electron microscopy images and dynamic light scattering of their Aβ aggregations were observed. Docking simulations revealed that the catechol moiety of the synthesized compounds can form hydrogen bonds with the key regions of Aβ and thereby inhibit Aβ aggregation.

Keywords:  Aggregation inhibition; Alzheimer’s disease; Amyloid β; Catechol derivatives

DOI:  https://doi.org/10.1016/j.bmcl.2024.129788
Nat Cell Biol. 2024 May 13.

Polyglutamine-mediated ribotoxicity disrupts proteostasis and stress responses in Huntington's disease.

Ranen Aviner, Ting-Ting Lee, Vincent B Masto, Kathy H Li, Raul Andino, Judith Frydman.

Huntington's disease (HD) is a neurodegenerative disorder caused by expansion of a CAG trinucleotide repeat in the Huntingtin (HTT) gene, encoding a homopolymeric polyglutamine (polyQ) tract. Although mutant HTT (mHTT) protein is known to aggregate, the links between aggregation and neurotoxicity remain unclear. Here we show that both translation and aggregation of wild-type HTT and mHTT are regulated by a stress-responsive upstream open reading frame and that polyQ expansions cause abortive translation termination and release of truncated, aggregation-prone mHTT fragments. Notably, we find that mHTT depletes translation elongation factor eIF5A in brains of symptomatic HD mice and cultured HD cells, leading to pervasive ribosome pausing and collisions. Loss of eIF5A disrupts homeostatic controls and impairs recovery from acute stress. Importantly, drugs that inhibit translation initiation reduce premature termination and mitigate this escalating cascade of ribotoxic stress and dysfunction in HD.

DOI: https://doi.org/10.1038/s41556-024-01414-x