scholarly journals DNAJ Proteins in neurodegeneration: essential and protective factors

2017 ◽  
Vol 373 (1738) ◽  
pp. 20160534 ◽  
Author(s):  
Christina Zarouchlioti ◽  
David A. Parfitt ◽  
Wenwen Li ◽  
Lauren M. Gittings ◽  
Michael E. Cheetham
Keyword(s):  
Quality Control ◽  
Neurodegenerative Diseases ◽  
Conformational Changes ◽  
Molecular Chaperones ◽  
Protein Quality ◽  
Misfolded Proteins ◽  
Protein Homeostasis ◽  
Polyglutamine Expansion ◽  
Binding Domains

Maintenance of protein homeostasis is vitally important in post-mitotic cells, particularly neurons. Neurodegenerative diseases such as polyglutamine expansion disorders—like Huntington's disease or spinocerebellar ataxia (SCA), Alzheimer's disease, fronto-temporal dementia (FTD), amyotrophic lateral sclerosis (ALS) and Parkinson's disease—are often characterized by the presence of inclusions of aggregated protein. Neurons contain complex protein networks dedicated to protein quality control and maintaining protein homeostasis, or proteostasis. Molecular chaperones are a class of proteins with prominent roles in maintaining proteostasis, which act to bind and shield hydrophobic regions of nascent or misfolded proteins while allowing correct folding, conformational changes and enabling quality control. There are many different families of molecular chaperones with multiple functions in proteostasis. The DNAJ family of molecular chaperones is the largest chaperone family and is defined by the J-domain, which regulates the function of HSP70 chaperones. DNAJ proteins can also have multiple other protein domains such as ubiquitin-interacting motifs or clathrin-binding domains leading to diverse and specific roles in the cell, including targeting client proteins for degradation via the proteasome, chaperone-mediated autophagy and uncoating clathrin-coated vesicles. DNAJ proteins can also contain ER-signal peptides or mitochondrial leader sequences, targeting them to specific organelles in the cell. In this review, we discuss the multiple roles of DNAJ proteins and in particular focus on the role of DNAJ proteins in protecting against neurodegenerative diseases caused by misfolded proteins. We also discuss the role of DNAJ proteins as direct causes of inherited neurodegeneration via mutations in DNAJ family genes. This article is part of the theme issue ‘Heat shock proteins as modulators and therapeutic targets of chronic disease: an integrated perspective’.

scholarly journals Proteinopathies and OXPHOS dysfunction in neurodegenerative diseases

2017 ◽  
Vol 216 (12) ◽  
pp. 3917-3929 ◽  
Author(s):  
Hibiki Kawamata ◽  
Giovanni Manfredi
Keyword(s):  
Nervous System ◽  
Oxidative Phosphorylation ◽  
Neurodegenerative Diseases ◽  
Gene Mutations ◽  
Misfolded Proteins ◽  
Protein Homeostasis ◽  
Abnormal Protein ◽  
Oxidative Phosphorylation System ◽  
Intermediate Metabolism

Mitochondria participate in essential processes in the nervous system such as energy and intermediate metabolism, calcium homeostasis, and apoptosis. Major neurodegenerative diseases are characterized pathologically by accumulation of misfolded proteins as a result of gene mutations or abnormal protein homeostasis. Misfolded proteins associate with mitochondria, forming oligomeric and fibrillary aggregates. As mitochondrial dysfunction, particularly of the oxidative phosphorylation system (OXPHOS), occurs in neurodegeneration, it is postulated that such defects are caused by the accumulation of misfolded proteins. However, this hypothesis and the pathological role of proteinopathies in mitochondria remain elusive. In this study, we critically review the proposed mechanisms whereby exemplary misfolded proteins associate with mitochondria and their consequences on OXPHOS.

scholarly journals Molecular chaperones and stress-inducible protein-sorting factors coordinate the spatiotemporal distribution of protein aggregates

2012 ◽  
Vol 23 (16) ◽  
pp. 3041-3056 ◽  
Author(s):  
Liliana Malinovska ◽  
Sonja Kroschwald ◽  
Matthias C. Munder ◽  
Doris Richter ◽  
Simon Alberti
Keyword(s):  
Quality Control ◽  
Molecular Chaperones ◽  
Cellular Response ◽  
Protein Quality ◽  
Acute Stress ◽  
Protein Sorting ◽  
Protein Quality Control ◽  
Normal Growth ◽  
Small Heat Shock Protein ◽  
Misfolded Proteins

Acute stress causes a rapid redistribution of protein quality control components and aggregation-prone proteins to diverse subcellular compartments. How these remarkable changes come about is not well understood. Using a phenotypic reporter for a synthetic yeast prion, we identified two protein-sorting factors of the Hook family, termed Btn2 and Cur1, as key regulators of spatial protein quality control in Saccharomyces cerevisiae. Btn2 and Cur1 are undetectable under normal growth conditions but accumulate in stressed cells due to increased gene expression and reduced proteasomal turnover. Newly synthesized Btn2 can associate with the small heat shock protein Hsp42 to promote the sorting of misfolded proteins to a peripheral protein deposition site. Alternatively, Btn2 can bind to the chaperone Sis1 to facilitate the targeting of misfolded proteins to a juxtanuclear compartment. Protein redistribution by Btn2 is accompanied by a gradual depletion of Sis1 from the cytosol, which is mediated by the sorting factor Cur1. On the basis of these findings, we propose a dynamic model that explains the subcellular distribution of misfolded proteins as a function of the cytosolic concentrations of molecular chaperones and protein-sorting factors. Our model suggests that protein aggregation is not a haphazard process but rather an orchestrated cellular response that adjusts the flux of misfolded proteins to the capacities of the protein quality control system.

Neurodegenerative Diseases as Protein Misfolding Disorders

2016 ◽  
Author(s):  
Tomohiro Nakamura ◽  
Stuart A. Lipton
Keyword(s):  
Quality Control ◽  
Neurodegenerative Diseases ◽  
Protein Misfolding ◽  
Protein Quality ◽  
Protein S ◽  
Ubiquitin Proteasome System ◽  
Misfolded Proteins ◽  
Redox Stress ◽  
Chemical Mechanisms ◽  
Ubiquitin Proteasome

Neurodegenerative diseases (NDDs) often represent disorders of protein folding. Rather than large aggregates, recent evidence suggests that soluble oligomers of misfolded proteins are the most neurotoxic species. Emerging evidence points to small, soluble oligomers of misfolded proteins as the cause of synaptic dysfunction and loss, the major pathological correlate to disease progression in many NDDs including Alzheimer’s disease. The protein quality control machinery of the cell, which includes molecular chaperones as found in the endoplasmic reticulum (ER), the ubiquitin-proteasome system (UPS), and various forms of autophagy, can counterbalance the accumulation of misfolded proteins to some extent. Their ability to eliminate the neurotoxic effects of misfolded proteins, however, declines with age. A plausible explanation for the age-dependent deterioration of the quality control machinery involves compromise of these systems by excessive generation of reactive oxygen species (ROS), such as superoxide anion (O2-), and reactive nitrogen species (RNS), such as nitric oxide (NO). The resulting redox stress contributes to the accumulation of misfolded proteins. Here, we focus on aberrantly increased generation of NO-related species since this process appears to accelerate the manifestation of key neuropathological features, including protein misfolding. We review the chemical mechanisms of posttranslational modification by RNS such as protein S-nitrosylation of critical cysteine thiol groups and nitration of tyrosine residues, showing how they contribute to the pathogenesis of NDDs.

scholarly journals The nucleolus functions as a phase-separated protein quality control compartment

Science ◽  
2019 ◽  
Vol 365 (6451) ◽  
pp. 342-347 ◽  
Author(s):  
F. Frottin ◽  
F. Schueder ◽  
S. Tiwary ◽  
R. Gupta ◽  
R. Körner ◽  
...  
Keyword(s):  
Quality Control ◽  
Protein Quality ◽  
Protein Quality Control ◽  
Misfolded Proteins ◽  
Control Mechanisms ◽  
Culture Cells ◽  
Irreversible Aggregation ◽  
Nuclear Proteome ◽  
Prolonged Stress

The nuclear proteome is rich in stress-sensitive proteins, which suggests that effective protein quality control mechanisms are in place to ensure conformational maintenance. We investigated the role of the nucleolus in this process. In mammalian tissue culture cells under stress conditions, misfolded proteins entered the granular component (GC) phase of the nucleolus. Transient associations with nucleolar proteins such as NPM1 conferred low mobility to misfolded proteins within the liquid-like GC phase, avoiding irreversible aggregation. Refolding and extraction of proteins from the nucleolus during recovery from stress was Hsp70-dependent. The capacity of the nucleolus to store misfolded proteins was limited, and prolonged stress led to a transition of the nucleolar matrix from liquid-like to solid, with loss of reversibility and dysfunction in quality control. Thus, we suggest that the nucleolus has chaperone-like properties and can promote nuclear protein maintenance under stress.

The role of protein quality control in mitochondrial protein homeostasis under oxidative stress

PROTEOMICS ◽  
2010 ◽  
Vol 10 (7) ◽  
pp. 1426-1443 ◽  
Author(s):  
Tom Bender ◽  
Claudia Leidhold ◽  
Thomas Ruppert ◽  
Sebastian Franken ◽  
Wolfgang Voos
Keyword(s):  
Oxidative Stress ◽  
Quality Control ◽  
Protein Quality ◽  
Mitochondrial Protein ◽  
Protein Quality Control ◽  
Protein Homeostasis

scholarly journals The Degradation-promoting Roles of Deubiquitinases Ubp6 and Ubp3 in Cytosolic and ER Protein Quality Control

2020 ◽  
Author(s):  
Hongyi Wu ◽  
Davis T.W. Ng ◽  
Ian Cheong ◽  
Paul Matsudaira
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Quality Control ◽  
Molecular Chaperones ◽  
Protein Quality ◽  
Protein Quality Control ◽  
Ubiquitin Proteasome System ◽  
Misfolded Proteins ◽  
Intracellular Proteins ◽  
Ubiquitin Proteasome ◽  
Free Ubiquitin

AbstractThe quality control of intracellular proteins is achieved by degrading misfolded proteins which cannot be refolded by molecular chaperones. In eukaryotes, such degradation is handled primarily by the ubiquitin-proteasome system. However, it remains unclear whether and how protein quality control deploys various deubiquitinases. To address this question, we screened deletions or mutation of the 20 deubiquitinase genes in Saccharomyces cerevisiae and discovered that almost half of the mutations slowed the removal of misfolded proteins whereas none of the remaining mutations accelerated this process significantly. Further characterization revealed that Ubp6 maintains the level of free ubiquitin to promote the elimination of misfolded cytosolic proteins, while Ubp3 supports the degradation of misfolded cytosolic and ER luminal proteins by different mechanisms.

scholarly journals Mechanismen und Funktionen von bakteriellen AAA+­Entfaltungsmaschinen

BIOspektrum ◽  
2021 ◽  
Vol 27 (1) ◽  
pp. 22-24
Author(s):  
Axel Mogk
Keyword(s):  
Quality Control ◽  
Drug Target ◽  
Protein Quality ◽  
Protein Quality Control ◽  
Stress Conditions ◽  
Misfolded Proteins ◽  
Antibacterial Drug ◽  
Protein Homeostasis ◽  
Antibacterial Drug Target

AbstractBacterial AAA+ proteins play crucial roles in proteostasis networks and ensure protein homeostasis during stress conditions. They function as ATP-dependent components of proteolytic complexes degrading misfolded proteins or as disaggregases reactivating aggregated proteins. AAA+ proteins generate an ATP-fueled threading force driving substrate unfolding and translocation. Their central functions in protein quality control qualify them as antibacterial drug target.

scholarly journals Protein Homeostasis Database: protein quality control in E.coli

2019 ◽  
Author(s):  
Reshmi Ramakrishnan ◽  
Bert Houben ◽  
Łukasz Kreft ◽  
Alexander Botzki ◽  
Joost Schymkowitz ◽  
...  
Keyword(s):  
Quality Control ◽  
Molecular Chaperones ◽  
Protein Quality ◽  
Trigger Factor ◽  
Proteolytic Degradation ◽  
Whole Genome ◽  
Protein Homeostasis ◽  
Web Interface ◽  
Nascent Chain

Abstract Motivation In vivo protein folding is governed by molecular chaperones, that escort proteins from their translational birth to their proteolytic degradation. In E.coli the main classes of chaperones that interact with the nascent chain are trigger factor, DnaK/J and GroEL/ES and several authors have performed whole-genome experiments to construct exhaustive client lists for each of these. Results We constructed a database collecting all publicly available data of experimental chaperone-interaction and -dependency data for the E.coli proteome, and enriched it with an extensive set of protein-specific as well as cell context-dependent proteostatic parameters. We made this publicly accessible via a web interface that allows to search for proteins or chaperone client lists, but also to profile user-specified datasets against all the collected parameters. We hope this will accelerate research in this field by quickly identifying differentiating features in datasets. Availability and implementation The Protein Homeostasis Database is freely available without any registration requirement at http://PHDB.switchlab.org/.

Sign in / Sign up

Export Citation Format

Share Document