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Bartolomé-Nafría A, García-Pardo J, Ventura S. Mutations in human prion-like domains: pathogenic but not always amyloidogenic. Prion 2024; 18:28-39. [PMID: 38512820 PMCID: PMC10962614 DOI: 10.1080/19336896.2024.2329186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Accepted: 03/06/2024] [Indexed: 03/23/2024] Open
Abstract
Heterogeneous nuclear ribonucleoproteins (hnRNPs) are multifunctional proteins with integral roles in RNA metabolism and the regulation of alternative splicing. These proteins typically contain prion-like domains of low complexity (PrLDs or LCDs) that govern their assembly into either functional or pathological amyloid fibrils. To date, over 60 mutations targeting the LCDs of hnRNPs have been identified and associated with a spectrum of neurodegenerative diseases including amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD), and Alzheimer's disease (AD). The cryo-EM structures of pathological and functional fibrils formed by different hnRNPs have been recently elucidated, including those of hnRNPA1, hnRNPA2, hnRNPDL-2, TDP-43, and FUS. In this review, we discuss the structural features of these amyloid assemblies, placing particular emphasis on scrutinizing the impact of prevalent disease-associated mutations mapping within their LCDs. By performing systematic energy calculations, we reveal a prevailing trend of destabilizing effects induced by these mutations in the amyloid structure, challenging the traditionally assumed correlation between pathogenicity and amyloidogenic propensity. Understanding the molecular basis of this discrepancy might provide insights for developing targeted therapeutic strategies to combat hnRNP-associated diseases.
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Affiliation(s)
- Andrea Bartolomé-Nafría
- Institut de Biotecnologia i de Biomedicina (IBB) and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Javier García-Pardo
- Institut de Biotecnologia i de Biomedicina (IBB) and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Salvador Ventura
- Institut de Biotecnologia i de Biomedicina (IBB) and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Barcelona, Spain
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Garcia-Pardo J, Ventura S. Cryo-EM structures of functional and pathological amyloid ribonucleoprotein assemblies. Trends Biochem Sci 2024; 49:119-133. [PMID: 37926650 DOI: 10.1016/j.tibs.2023.10.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 10/05/2023] [Accepted: 10/06/2023] [Indexed: 11/07/2023]
Abstract
Amyloids are implicated in neurodegenerative and systemic diseases, yet they serve important functional roles in numerous organisms. Heterogeneous nuclear ribonucleoproteins (hnRNPs) represent a large family of RNA-binding proteins (RBPs) that control central events of RNA biogenesis in normal and diseased cellular conditions. Many of these proteins contain prion-like sequences of low complexity, which not only assemble into functional fibrils in response to cellular cues but can also lead to disease when missense mutations arise in their sequences. Recent advances in cryo-electron microscopy (cryo-EM) have provided unprecedented high-resolution structural insights into diverse amyloid assemblies formed by hnRNPs and structurally related RBPs, including TAR DNA-binding protein 43 (TDP-43), Fused in Sarcoma (FUS), Orb2, hnRNPA1, hnRNPA2, and hnRNPDL-2. This review provides a comprehensive overview of these structures and explores their functional and pathological implications.
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Affiliation(s)
- Javier Garcia-Pardo
- Institut de Biotecnologia i de Biomedicina (IBB) and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, 08193, Bellaterra, Barcelona, Spain.
| | - Salvador Ventura
- Institut de Biotecnologia i de Biomedicina (IBB) and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, 08193, Bellaterra, Barcelona, Spain.
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Cryo-EM structure of hnRNPDL-2 fibrils, a functional amyloid associated with limb-girdle muscular dystrophy D3. Nat Commun 2023; 14:239. [PMID: 36646699 PMCID: PMC9842712 DOI: 10.1038/s41467-023-35854-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Accepted: 01/04/2023] [Indexed: 01/18/2023] Open
Abstract
hnRNPDL is a ribonucleoprotein (RNP) involved in transcription and RNA-processing that hosts missense mutations causing limb-girdle muscular dystrophy D3 (LGMD D3). Mammalian-specific alternative splicing (AS) renders three natural isoforms, hnRNPDL-2 being predominant in humans. We present the cryo-electron microscopy structure of full-length hnRNPDL-2 amyloid fibrils, which are stable, non-toxic, and bind nucleic acids. The high-resolution amyloid core consists of a single Gly/Tyr-rich and highly hydrophilic filament containing internal water channels. The RNA binding domains are located as a solenoidal coat around the core. The architecture and activity of hnRNPDL-2 fibrils are reminiscent of functional amyloids, our results suggesting that LGMD D3 might be a loss-of-function disease associated with impaired fibrillation. Strikingly, the fibril core matches exon 6, absent in the soluble hnRNPDL-3 isoform. This provides structural evidence for AS controlling hnRNPDL assembly by precisely including/skipping an amyloid exon, a mechanism that holds the potential to generate functional diversity in RNPs.
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Lai MY, Li J, Zhang XX, Wu W, Li ZP, Sun ZX, Zhao MY, Yang DM, Wang DD, Li W, Zhao DM, Zhou XM, Yang LF. SARM1 participates in axonal degeneration and mitochondrial dysfunction in prion disease. Neural Regen Res 2022; 17:2293-2299. [PMID: 35259852 PMCID: PMC9083142 DOI: 10.4103/1673-5374.337051] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Prion disease represents a group of fatal neurogenerative diseases in humans and animals that are associated with energy loss, axonal degeneration, and mitochondrial dysfunction. Axonal degeneration is an early hallmark of neurodegeneration and is triggered by SARM1. We found that depletion or dysfunctional mutation of SARM1 protected against NAD+ loss, axonal degeneration, and mitochondrial functional disorder induced by the neurotoxic peptide PrP106-126. NAD+ supplementation rescued prion-triggered axonal degeneration and mitochondrial dysfunction and SARM1 overexpression suppressed this protective effect. NAD+ supplementation in PrP106-126-incubated N2a cells, SARM1 depletion, and SARM1 dysfunctional mutation each blocked neuronal apoptosis and increased cell survival. Our results indicate that the axonal degeneration and mitochondrial dysfunction triggered by PrP106-126 are partially dependent on SARM1 NADase activity. This pathway has potential as a therapeutic target in the early stages of prion disease.
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Affiliation(s)
- Meng-Yu Lai
- National Animal Transmissible Spongiform Encephalopathy Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Jie Li
- National Animal Transmissible Spongiform Encephalopathy Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Xi-Xi Zhang
- National Animal Transmissible Spongiform Encephalopathy Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Wei Wu
- National Animal Transmissible Spongiform Encephalopathy Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Zhi-Ping Li
- National Animal Transmissible Spongiform Encephalopathy Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Zhi-Xin Sun
- National Animal Transmissible Spongiform Encephalopathy Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Meng-Yang Zhao
- National Animal Transmissible Spongiform Encephalopathy Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Dong-Ming Yang
- National Animal Transmissible Spongiform Encephalopathy Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Dong-Dong Wang
- National Animal Transmissible Spongiform Encephalopathy Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Wen Li
- National Animal Transmissible Spongiform Encephalopathy Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - De-Ming Zhao
- National Animal Transmissible Spongiform Encephalopathy Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Xiang-Mei Zhou
- National Animal Transmissible Spongiform Encephalopathy Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Li-Feng Yang
- National Animal Transmissible Spongiform Encephalopathy Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, China
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In-Silico Analysis of pH-Dependent Liquid-Liquid Phase Separation in Intrinsically Disordered Proteins. Biomolecules 2022; 12:biom12070974. [PMID: 35883530 PMCID: PMC9313257 DOI: 10.3390/biom12070974] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 07/06/2022] [Accepted: 07/08/2022] [Indexed: 02/04/2023] Open
Abstract
Intrinsically disordered proteins (IDPs) are essential players in the assembly of biomolecular condensates during liquid–liquid phase separation (LLPS). Disordered regions (IDRs) are significantly exposed to the solvent and, therefore, highly influenced by fluctuations in the microenvironment. Extrinsic factors, such as pH, modify the solubility and disorder state of IDPs, which in turn may impact the formation of liquid condensates. However, little attention has been paid to how the solution pH influences LLPS, despite knowing that this process is context-dependent. Here, we have conducted a large-scale in-silico analysis of pH-dependent solubility and disorder in IDRs known to be involved in LLPS (LLPS-DRs). We found that LLPS-DRs present maximum solubility around physiological pH, where LLPS often occurs, and identified significant differences in solubility and disorder between proteins that can phase-separate by themselves or those that require a partner. We also analyzed the effect of mutations in the resulting solubility profiles of LLPS-DRs and discussed how, as a general trend, LLPS-DRs display physicochemical properties that permit their LLPS at physiologically relevant pHs.
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