Co-translational control for misfolded proteins and their association with mRNA quality control.

2013 ◽  
pp. 3039
Author(s):  
Parmit Singh
Keyword(s):  
Quality Control ◽  
Translational Control ◽  
Misfolded Proteins

scholarly journals Limited ER quality control for GPI-anchored proteins

2016 ◽  
Vol 213 (6) ◽  
pp. 693-704 ◽  
Author(s):  
Natalia Sikorska ◽  
Leticia Lemus ◽  
Auxiliadora Aguilera-Romero ◽  
Javier Manzano-Lopez ◽  
Howard Riezman ◽  
...  
Keyword(s):  
Quality Control ◽  
Endoplasmic Reticulum ◽  
Protein Folding ◽  
Misfolded Proteins ◽  
Control Mechanisms ◽  
Gpi Anchor ◽  
Er Quality Control ◽  
Entire Class ◽  
Er Export ◽  
Export Signal

Endoplasmic reticulum (ER) quality control mechanisms target terminally misfolded proteins for ER-associated degradation (ERAD). Misfolded glycophosphatidylinositol-anchored proteins (GPI-APs) are, however, generally poor ERAD substrates and are targeted mainly to the vacuole/lysosome for degradation, leading to predictions that a GPI anchor sterically obstructs ERAD. Here we analyzed the degradation of the misfolded GPI-AP Gas1* in yeast. We could efficiently route Gas1* to Hrd1-dependent ERAD and provide evidence that it contains a GPI anchor, ruling out that a GPI anchor obstructs ERAD. Instead, we show that the normally decreased susceptibility of Gas1* to ERAD is caused by canonical remodeling of its GPI anchor, which occurs in all GPI-APs and provides a protein-independent ER export signal. Thus, GPI anchor remodeling is independent of protein folding and leads to efficient ER export of even misfolded species. Our data imply that ER quality control is limited for the entire class of GPI-APs, many of them being clinically relevant.

scholarly journals Cdc48 regulates intranuclear quality control sequestration of the Hsh155 splicing factor

2020 ◽  
Author(s):  
Veena Mathew ◽  
Arun Kumar ◽  
Yangyang Kate Jiang ◽  
Kyra West ◽  
Annie S Tam ◽  
...  
Keyword(s):  
Quality Control ◽  
Essential Role ◽  
Protein Quality ◽  
Protein Quality Control ◽  
Genotoxic Stress ◽  
Stress Conditions ◽  
Splicing Factor ◽  
Misfolded Proteins ◽  
Dna Complexes ◽  
Partner Proteins

Cdc48/VCP is a highly conserved ATPase chaperone that plays an essential role in the assembly or disassembly of protein-DNA complexes and in degradation of misfolded proteins. We find that Cdc48 accumulates during cellular stress at intranuclear protein quality control (INQ) sites. Cdc48 function is required to suppress INQ formation under non-stress conditions and to promote recovery following genotoxic stress. Cdc48 physically associates with the INQ substrate and splicing factor Hsh155 and regulates its assembly with partner proteins. Accordingly, cdc48 mutants have defects in splicing and show spontaneous distribution of Hsh155 to INQ aggregates where it is stabilized. Overall, this study shows that Cdc48 regulates deposition of proteins at INQ and suggests a previously unknown role for Cdc48 in the regulation or stability of splicing subcomplexes.

Protein Quality Control Degradation in the Nucleus

2018 ◽  
Vol 87 (1) ◽  
pp. 725-749 ◽  
Author(s):  
Charisma Enam ◽  
Yifat Geffen ◽  
Tommer Ravid ◽  
Richard G. Gardner
Keyword(s):  
Quality Control ◽  
Protein Misfolding ◽  
Protein Quality ◽  
Current Knowledge ◽  
Protein Quality Control ◽  
Ubiquitin Proteasome System ◽  
Misfolded Proteins ◽  
Cellular Processes ◽  
Human Disorders ◽  
Protein Misfolding And Aggregation

Nuclear proteins participate in diverse cellular processes, many of which are essential for cell survival and viability. To maintain optimal nuclear physiology, the cell employs the ubiquitin-proteasome system to eliminate damaged and misfolded proteins in the nucleus that could otherwise harm the cell. In this review, we highlight the current knowledge about the major ubiquitin-protein ligases involved in protein quality control degradation (PQCD) in the nucleus and how they orchestrate their functions to eliminate misfolded proteins in different nuclear subcompartments. Many human disorders are causally linked to protein misfolding in the nucleus, hence we discuss major concepts that still need to be clarified to better understand the basis of the nuclear misfolded proteins’ toxic effects. Additionally, we touch upon potential strategies for manipulating nuclear PQCD pathways to ameliorate diseases associated with protein misfolding and aggregation in the nucleus.

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.

scholarly journals Ubiquitin conjugation triggers misfolded protein sequestration into quality control foci when Hsp70 chaperone levels are limiting

2013 ◽  
Vol 24 (13) ◽  
pp. 2076-2087 ◽  
Author(s):  
Ayala Shiber ◽  
William Breuer ◽  
Michael Brandeis ◽  
Tommer Ravid
Keyword(s):  
Quality Control ◽  
Heat Shock Protein 70 ◽  
Inclusion Bodies ◽  
Amyloid Plaques ◽  
Model System ◽  
Misfolded Proteins ◽  
Misfolded Protein ◽  
Pathological Conditions ◽  
Hsp70 Chaperone ◽  
Ubiquitin Conjugation

Ubiquitin accumulation in amyloid plaques is a pathological marker observed in the vast majority of neurodegenerative diseases, yet ubiquitin function in these inclusions is controversial. It has been suggested that ubiquitylated proteins are directed to inclusion bodies under stress conditions, when both chaperone-mediated refolding and proteasomal degradation are compromised or overwhelmed. Alternatively, ubiquitin and chaperones may be recruited to preformed inclusions to promote their elimination. We address this issue using a yeast model system, based on expression of several mildly misfolded degradation substrates in cells with altered chaperone content. We find that the heat shock protein 70 (Hsp70) chaperone pair Ssa1/Ssa2 and the Hsp40 cochaperone Sis1 are essential for degradation. Substrate ubiquitylation is strictly dependent on Sis1, whereas Ssa1 and Ssa2 are dispensable. Remarkably, in Ssa1/Ssa2-depleted cells, ubiquitylated substrates are sequestered into detergent-insoluble, Hsp42-positive inclusion bodies. Unexpectedly, sequestration is abolished by preventing substrate ubiquitylation. We conclude that Hsp40 is required for the targeting of misfolded proteins to the ubiquitylation machinery, whereas the decision to degrade or sequester ubiquitylated proteins is mediated by the Hsp70s. Accordingly, diminished Hsp70 levels, as observed in aging or certain pathological conditions, might be sufficient to trigger ubiquitin-dependent sequestration of partially misfolded proteins into inclusion bodies.

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