bims-proned 2024-11-17 papers

bims-proned

Biomed News

on Proteostasis in neurodegeneration

Issue of 2024–11–17
nine papers selected by
Verena Kohler, Umeå University

Identification of a Hidden, Highly Aggregation-Prone Intermediate of Full-Length TDP-43 That Triggers its Misfolding and Amyloid Aggregation.
Targeting protein aggregation using a cocoa-bean shell extract to reduce α-synuclein toxicity in models of Parkinson's disease.
Optimizing TDP-43 silencing with siRNA-loaded polymeric nanovectors in neuronal cells for therapeutic applications: balancing knockdown and function.
Targeting chaperone-mediated autophagy in neurodegenerative diseases: mechanisms and therapeutic potential.
The Inhibition of Serum Amyloid A Protein Aggregation by a Five-Residue Peptidomimetic: Structural and Morphological Insights.
CK and LRRK2 Involvement in Neurodegenerative Diseases.
Autophagy-lysosomal pathway impairment and cathepsin dysregulation in Alzheimer's disease.
Acute introduction of monomeric or multimeric α-synuclein induces distinct impacts on synaptic vesicle trafficking at lamprey giant synapses.
The structure of a Tau fragment bound to tubulin prompts new hypotheses on Tau mechanism and oligomerization.

Biochemistry. 2024 Nov 12.

Identification of a Hidden, Highly Aggregation-Prone Intermediate of Full-Length TDP-43 That Triggers its Misfolding and Amyloid Aggregation.

Abhilasha A Doke, Santosh Kumar Jha.

In cells, TDP-43 is a crucial protein that can form harmful amyloid aggregates linked to fatal and incurable human neurodegenerative disorders. Normally, TDP-43 exists in a smaller soluble native state that prevents aggregation. However, aging and stress can destabilize this native state, leading to the formation of disease-causing amyloid aggregates via the formation of partially unfolded, high-energy intermediates with a greater tendency to aggregate. These intermediates are crucial in the early stages of amyloid formation and are challenging to study due to their low stability. Understanding the structure of these early aggregation-prone states of TDP-43 is essential for designing effective treatments for TDP-43 proteinopathies. Targeting these initial intermediates could be more effective than focusing on fully formed amyloid aggregates. By disrupting the aggregation process at this early stage, we may be able to prevent the progression of diseases related to TDP-43 aggregation. Hence, we decided to uncover the hidden, high-energy intermediates in equilibrium with the native states of TDP-43 by modulating the thermodynamic stability of the soluble native dimer (N form) and monomeric molten globular state (MG form) of full-length TDP-43. The thermodynamic modulation performed in the current study successfully revealed the highly aggregation-prone intermediate of full-length TDP-43, i.e., PUF. Moreover, we observed that along with high aggregation propensity, the aggregation kinetics and mechanisms of PUF differ from previously identified intermediates of full-length TDP-43 (the MG and I forms). The information regarding the initial aggregation-prone state of full-length TDP-43 could lead to therapies for amyloid diseases by halting early protein aggregation.

DOI: https://doi.org/10.1021/acs.biochem.4c00389
Curr Res Food Sci. 2024 ;9 100888

Targeting protein aggregation using a cocoa-bean shell extract to reduce α-synuclein toxicity in models of Parkinson's disease.

Farida Tripodi, Alessia Lambiase, Hind Moukham, Giorgia Spandri, Maura Brioschi, Ermelinda Falletta, Annalisa D'Urzo, Marina Vai, Francesco Abbiati, Stefania Pagliari, Andrea Salvo, Mattia Spano, Luca Campone, Massimo Labra, Paola Coccetti.

  Neurodegenerative diseases are among the major challenges in modern medicine, due to the progressive aging of the world population. Among these, Parkinson's disease (PD) affects 10 million people worldwide and is associated with the aggregation of the presynaptic protein α-synuclein (α-syn). Here we use two different PD models, yeast cells and neuroblastoma cells overexpressing α-syn, to investigate the protective effect of an extract from the cocoa shell, which is a by-product of the roasting process of cocoa beans. The LC-ESI-qTOF-MS and NMR analyses allow the identification of amino acids (including the essential ones), organic acids, lactate and glycerol, confirming also the presence of the two methylxanthines, namely caffeine and theobromine. The present study demonstrates that the supplementation with the cocoa bean shell extract (CBSE) strongly improves the longevity of yeast cells expressing α-syn, reducing the level of reactive oxygen species, activating autophagy and reducing the intracellular protein aggresomes. These anti-aggregation properties are confirmed also in neuroblastoma cells, where CBSE treatment leads to activation of AMPK kinase and to a significant reduction of toxic α-syn oligomers. Results obtained by surface plasmon resonance (SPR) assay highlights that CBSE binds α-syn protein in a concentration-dependent manner, supporting its inhibitory role on the amyloid aggregation of α-syn. These findings suggest that the supplementation with CBSE in the form of nutraceuticals may represent a promising way to prevent neurodegenerative diseases associated with α-syn aggregation.

Keywords:  Cocoa; Food waste valorization; Human α-synuclein; Parkinson's disease (PD); Saccharomyces cerevisiae

DOI:  https://doi.org/10.1016/j.crfs.2024.100888
Nanoscale. 2024 Nov 14.

Optimizing TDP-43 silencing with siRNA-loaded polymeric nanovectors in neuronal cells for therapeutic applications: balancing knockdown and function.

Annamaria Russo, Gabriele Maiorano, Barbara Cortese, Stefania D'Amone, Alessandra Invidia, Angelo Quattrini, Alessandro Romano, Giuseppe Gigli, Ilaria E Palamà.

TAR DNA-binding protein 43 (TDP-43) is a ubiquitously expressed DNA/RNA binding protein critical for regulating gene expression, including transcription, splicing, mRNA stability, and protein translation. Aggregation of pathological TDP-43 proteins in the cytoplasm of neurons and glial cells appears to be a common feature of amyotrophic lateral sclerosis (ALS) and other neurodegenerative diseases such as frontotemporal dementia (FTD), contributing to motor neuron degeneration and clinical symptoms. Downregulation of TDP-43 expression to prevent or reduce the formation of pathological aggregates is a potential therapeutic approach for treating TDP-43-related diseases. However, therapeutic strategies to reduce TDP-43 aggregation face significant challenges, as the downregulation of TDP-43 must balance the need to maintain its normal functions, which are essential for RNA metabolism and cellular homeostasis. In this study, we developed novel polymeric nanovectors for the delivery of TDP-43 siRNAs in neuronal cells. These nanovectors were designed to provide adequate TDP-43 silencing to achieve the desired functional reduction of TDP-43 levels, thereby optimizing its impact on cellular functions. Our results demonstrate that the polymeric nanovector formulations effectively reduced TDP-43 mRNA and protein levels to an extent comparable to those observed with traditional lipid-based systems. Concurrently, the polymeric nanovectors exhibited an enhanced capacity to reduce stress granules (SG) formation and facilitate TDP-43-containing SG disassembly, while preserving its essential cellular functions. This study provides the first evidence that polymeric nanovectors may be a valuable tool for developing therapeutic strategies to treat TDP-43 protein diseases, such as ALS and FTD, by directly silencing TDP-43 to reduce its aggregation.

DOI: https://doi.org/10.1039/d4nr03159h
Acta Pharmacol Sin. 2024 Nov 15.

Targeting chaperone-mediated autophagy in neurodegenerative diseases: mechanisms and therapeutic potential.

Jin Wu, Wan Xu, Ying Su, Guang-Hui Wang, Jing-Jing Ma.

  The pathological hallmarks of various neurodegenerative diseases including Parkinson's disease and Alzheimer's disease prominently feature the accumulation of misfolded proteins and neuroinflammation. Chaperone-mediated autophagy (CMA) has emerged as a distinct autophagic process that coordinates the lysosomal degradation of specific proteins bearing the pentapeptide motif Lys-Phe-Glu-Arg-Gln (KFERQ), a recognition target for the cytosolic chaperone HSC70. Beyond its role in protein quality control, recent research underscores the intimate interplay between CMA and immune regulation in neurodegeneration. In this review, we illuminate the molecular mechanisms and regulatory pathways governing CMA. We further discuss the potential roles of CMA in maintaining neuronal proteostasis and modulating neuroinflammation mediated by glial cells. Finally, we summarize the recent advancements in CMA modulators, emphasizing the significance of activating CMA for the therapeutic intervention in neurodegenerative diseases.

Keywords:  CMA modulators; chaperone-mediated autophagy; neurodegenerative diseases; neuroinflammation; neuronal proteostasis

DOI:  https://doi.org/10.1038/s41401-024-01416-3
Molecules. 2024 Oct 31. pii: 5165. [Epub ahead of print]29(21):

The Inhibition of Serum Amyloid A Protein Aggregation by a Five-Residue Peptidomimetic: Structural and Morphological Insights.

Julia Witkowska, Sandra Skibiszewska, Paweł Wityk, Marcel Pilarski, Elżbieta Jankowska.

  Serum amyloid A (SAA) is a small protein consisting of 104 residues and, under physiological conditions, exists mainly in hexameric form. It belongs to the positive acute-phase proteins, which means that its plasma concentration increases rapidly in response to injury, inflammation, and infection. The accumulation of SAA molecules promotes the formation of amyloid aggregates, which deposit extracellularly in many organs, causing their dysfunction. In our previous work, we successfully designed a peptidomimetic that inhibited the aggregation of amyloidogenic SAA fragments. In the present paper, we show how the same inhibitor, named saa3Dip, affects the oligomerization and aggregation processes of MetSAA1.1 protein. The thioflavin T assay showed that saa3Dip inhibited its fibrillization. The measurement of the internal fluorophore fluorescence (Trp) showed differences that occurred in the tertiary structure of MetSAA1.1 in the presence of the inhibitor, which was also confirmed by CD spectra in the aromatic range. FTIR results suggested that saa3Dip could stabilize some fragments of the native structure of MetSAA1.1, which was confirmed by determining the melting temperature (Tm) of the protein-inhibitor complex. AFM images demonstrated that the presence of saa3Dip prevented the formation of large SAA aggregates. Our results suggest that saa3Dip stabilizes the native conformation of MetSAA1.1.

Keywords:  aggregation; inhibitor; serum amyloid A

DOI:  https://doi.org/10.3390/molecules29215165
Int J Mol Sci. 2024 Oct 30. pii: 11661. [Epub ahead of print]25(21):

CK and LRRK2 Involvement in Neurodegenerative Diseases.

Valentina Bova, Deborah Mannino, Anna Paola Capra, Marika Lanza, Nicoletta Palermo, Alessia Filippone, Emanuela Esposito.

  Neurodegenerative diseases (NDDs) are currently the most widespread neuronal pathologies in the world. Among these, the most widespread are Alzheimer's disease (AD), dementia, Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), and Huntington's disease (HD)-all characterized by a progressive loss of neurons in specific regions of the brain leading to varied clinical symptoms. At the basis of neurodegenerative diseases, an emerging role is played by genetic mutations in the leucine-rich repeat kinase 2 (LRRK2) gene that cause increased LRRK2 activity with consequent alteration of neuronal autophagy pathways. LRRK2 kinase activity requires GTPase activity which functions independently of kinase activity and is required for neurotoxicity and to potentiate neuronal death. Important in the neurodegeneration process is the upregulation of casein kinase (CK), which causes the alteration of the AMPK pathway by enhancing the phosphorylation of α-synuclein and huntingtin proteins, known to be involved in PD and HD, and increasing the accumulation of the amyloid-β protein (Aβ) for AD. Recent research has identified CK of the kinases upstream of LRRK2 as a regulator of the stability of the LRRK2 protein. Based on this evidence, this review aims to understand the direct involvement of individual kinases in NDDs and how their crosstalk may impact the pathogenesis and early onset of neurodegenerative diseases.

Keywords:  casein kinases; degradative pathways; leucine riche-repeat kinase; neurodegeneration

DOI:  https://doi.org/10.3390/ijms252111661
Front Mol Biosci. 2024 ;11 1490275

Autophagy-lysosomal pathway impairment and cathepsin dysregulation in Alzheimer's disease.

Alquiandra Stefani Ferreira Mançano, Juliana Guanaes Pina, Bruna Rojas Froes, Juliana Mozer Sciani.

  Alzheimer's disease (AD) is characterized by neuronal loss, attributed to amyloid-beta (Aβ) aggregation and accumulation. The autophagy-lysosomal pathway, including cathepsins B and D, is crucial for protein degradation and clearance, but it is impaired in some diseases. This review summarizes current knowledge on the dysregulation of this pathway in AD. Accumulating evidence suggests that Aβ overload impairs autophagy-lysosomal function and cathepsin activity, exacerbating Aβ accumulation and neurodegeneration. However, the precise mechanisms underlying these interactions remain elusive. Despite these challenges, targeting the lysosomal pathway emerges as a promising therapeutic strategy, and a comprehensive understanding of the autophagy-lysosomal system is essential to develop effective interventions for AD.

Keywords:  Alzheimer’s disease; autophagy; cathepsin B; cathepsin D; lysosome; β-amyloid

DOI:  https://doi.org/10.3389/fmolb.2024.1490275
J Physiol. 2024 Nov 12.

Acute introduction of monomeric or multimeric α-synuclein induces distinct impacts on synaptic vesicle trafficking at lamprey giant synapses.

Cristina Román-Vendrell, Jaqulin N Wallace, Aurelia Hays Watson, Meral Celikag, Tim Bartels, Jennifer R Morgan.

  Synaptic aggregation of α-synuclein often occurs in Parkinson's disease (PD), dementia with Lewy bodies (DLB) and other synucleinopathies and is associated with cognitive deficits and dementia. Thus, it is important to understand how accumulation of α-synuclein affects synapse structure and function. Native, physiological α-synuclein comprises a mixture of tetramers and related physiological oligomers (60-100 kDa) in equilibrium with monomeric α-synuclein. We previously demonstrated that acutely increasing the levels of physiological α-synuclein impaired intracellular synaptic vesicle trafficking and produced a pleiotropic phenotype, raising questions about which aspects of the synaptic phenotype were due to multimeric versus monomeric α-synuclein. Here, we address this by taking advantage of the unique features of the lamprey giant reticulospinal (RS) synapse, a vertebrate synapse that is amenable to acute perturbations of presynaptic processes via microinjection of purified proteins. α-Synuclein monomers and multimers were purified from HEK cells and separately introduced to lamprey synapses. Ultrastructural analysis revealed that both multimeric and monomeric α-synuclein impaired intracellular vesicle trafficking, leading to a loss of synaptic vesicles and buildup of endosomes. However, while monomeric α-synuclein additionally induced atypical fusion/fission at the active zone and impaired clathrin-mediated endocytosis, multimeric α-synuclein did not. Conversely, multimeric α-synuclein led to a decrease in synaptic vesicle docking, which was not observed with monomeric α-synuclein. These data provide further evidence that different molecular species of α-synuclein produce distinct and complex impacts on synaptic vesicle trafficking and reveal important insights into the cell biological processes that are affected in PD and DLB. KEY POINTS: α-Synuclein accumulation at synapses is associated with cognitive decline and dementia in Parkinson's disease and other synucleinopathies. We previously showed that acute introduction of excess human brain-derived α-synuclein to lamprey giant synapses caused pleiotropic phenotypes on synaptic vesicle trafficking, probably due to the mixture of molecular species of α-synuclein. Here, we dissected which aspects of the synaptic phenotypes were caused by monomeric (14 kDa) or multimeric (60-100 kDa) α-synuclein by purifying each molecular species and introducing each one separately to synapses via axonal microinjection. While monomeric α-synuclein inhibited clathrin-mediated synaptic vesicle endocytosis, multimeric α-synuclein primarily impaired endosomal trafficking. These findings reveal that different molecular species of α-synuclein have distinct impacts on synapses, suggesting different cellular and molecular targets.

Keywords:  Parkinson's disease; clathrin; endocytosis; endosome

DOI:  https://doi.org/10.1113/JP286281
PNAS Nexus. 2024 Nov;3(11): pgae487

The structure of a Tau fragment bound to tubulin prompts new hypotheses on Tau mechanism and oligomerization.

Liza Ammar Khodja, Valérie Campanacci, Guy Lippens, Benoît Gigant.

  Tau is a protein involved in the regulation of axonal microtubules in neurons. In pathological conditions, it forms filamentous aggregates which are molecular markers of neurodegenerative diseases known as tauopathies. Structures of Tau in fibrils or bound to the microtubule have been reported. We present here a structure of a Tau construct comprising the PHF6 motif, an oligopeptide involved in Tau aggregation, as a complex with tubulin. This Tau fragment binds as a dimer to a new site which, when transposed to the microtubule, would correspond to a pore between protofilaments. These results raise new hypotheses on Tau-induced microtubule assembly and stabilization and on Tau oligomerization.

Keywords:  cytoskeleton; microtubule dynamics; protein engineering; structural biology; tauopathies

DOI:  https://doi.org/10.1093/pnasnexus/pgae487