scholarly journals RNA nucleotide repeats induce mitochondrial dysfunction and the ribosome associated quality control

2021 ◽  
Author(s):  
Joana Teixeira ◽  
Anu-Mari Harju ◽  
Alaa Othman ◽  
Ove Eriksson ◽  
Ana Sofia Brandão ◽  
...  
Keyword(s):  
Quality Control ◽  
Mitochondrial Dysfunction ◽  
Rna Binding ◽  
Protein Quality ◽  
Coenzyme Q ◽  
Neuromuscular Disorders ◽  
Mitochondrial Morphology ◽  
Binding Factor ◽  
Nucleotide Repeats ◽  
Control Complex

Nucleotide repeat sequences are prevalent in the genome and expansion of these sequences is associated with more than 40 neuromuscular disorders. To understand the pathogenic mechanisms underlying RNA-repeat toxicity, we performed a genetic screen in a Caenorhabditis elegans model expressing an expanded CUG repeat specifically in the muscle. Here, we show that expression of this RNA repeat impairs motility by mitochondrial dysfunction, disrupting mitochondrial morphology and respiration. The phenotype is dependent on the RNA-binding factor MBL-1 and requires factors from the ribosome associated protein quality control complex. Furthermore, Coenzyme Q supplementation rescued the motility impairment and all of the mitochondrial phenotypes. Together, our data reveal the importance of mitochondrial dysfunction in the molecular pathogenesis of RNA repeat expansion disorders.

scholarly journals Translational Regulation of Pmt1 and Pmt2 by Bfr1 Affects Unfolded Protein O-Mannosylation

2019 ◽  
Vol 20 (24) ◽  
pp. 6220 ◽  
Author(s):  
Joan Castells-Ballester ◽  
Natalie Rinis ◽  
Ilgin Kotan ◽  
Lihi Gal ◽  
Daniela Bausewein ◽  
...  
Keyword(s):  
Quality Control ◽  
Translational Regulation ◽  
Secretory Pathway ◽  
Rna Binding ◽  
Protein Quality ◽  
Fluorescent Protein ◽  
Brefeldin A ◽  
Protein Quality Control ◽  
Ribosome Profiling ◽  
Unfolded Protein

O-mannosylation is implicated in protein quality control in Saccharomyces cerevisiae due to the attachment of mannose to serine and threonine residues of un- or misfolded proteins in the endoplasmic reticulum (ER). This process also designated as unfolded protein O-mannosylation (UPOM) that ends futile folding cycles and saves cellular resources is mainly mediated by protein O-mannosyltransferases Pmt1 and Pmt2. Here we describe a genetic screen for factors that influence O-mannosylation in yeast, using slow-folding green fluorescent protein (GFP) as a reporter. Our screening identifies the RNA binding protein brefeldin A resistance factor 1 (Bfr1) that has not been linked to O-mannosylation and ER protein quality control before. We find that Bfr1 affects O-mannosylation through changes in Pmt1 and Pmt2 protein abundance but has no effect on PMT1 and PMT2 transcript levels, mRNA localization to the ER membrane or protein stability. Ribosome profiling reveals that Bfr1 is a crucial factor for Pmt1 and Pmt2 translation thereby affecting unfolded protein O-mannosylation. Our results uncover a new level of regulation of protein quality control in the secretory pathway.

scholarly journals Structural basis for translational surveillance by the large ribosomal subunit-associated protein quality control complex

2014 ◽  
Vol 111 (45) ◽  
pp. 15981-15986 ◽  
Author(s):  
Dmitry Lyumkis ◽  
Dario Oliveira dos Passos ◽  
Erich B. Tahara ◽  
Kristofor Webb ◽  
Eric J. Bennett ◽  
...  
Keyword(s):  
Quality Control ◽  
Protein Quality ◽  
Ribosomal Subunit ◽  
Protein Quality Control ◽  
Structural Basis ◽  
Large Ribosomal Subunit ◽  
Control Complex

scholarly journals Translational regulation of Pmt1 and Pmt2 by Bfr1 affects unfolded protein O-mannosylation

2019 ◽  
Author(s):  
Joan Castells-Ballester ◽  
Natalie Rinis ◽  
Ilgin Kotan ◽  
Lihi Gal ◽  
Daniela Bausewein ◽  
...  
Keyword(s):  
Quality Control ◽  
Translational Regulation ◽  
Secretory Pathway ◽  
Rna Binding ◽  
Protein Quality ◽  
Brefeldin A ◽  
Protein Quality Control ◽  
Ribosome Profiling ◽  
Protein Abundance ◽  
Unfolded Protein

ABSTRACTO-mannosylation is implicated in protein quality control in Saccharomyces cerevisiae due to the attachment of mannose to serine and threonine residues of un- or misfolded proteins in the endoplasmic reticulum (ER). This process also designated as unfolded protein O-mannosylation (UPOM) that ends futile folding cycles and saves cellular resources is mainly mediated by protein O-mannosyltransferases Pmt1 and Pmt2. Here we describe a genetic screen for factors that influence O-mannosylation in yeast, using slow-folding GFP as a reporter. Our screening identifies the RNA binding protein brefeldin A resistance factor 1 (Bfr1) that has not been linked to O-mannosylation and ER protein quality control before. We find that Bfr1 affects O-mannosylation through changes in Pmt1 and Pmt2 protein abundance, but has no effect on PMT1 and PMT2 transcript levels, mRNA localization to the ER membrane or protein stability. Ribosome profiling reveals that Bfr1 is a crucial factor for Pmt1 and Pmt2 translation thereby affecting unfolded protein O-mannosylation. Our results uncover a new level of regulation of protein quality control in the secretory pathway.

scholarly journals RNA Gelation in Repeat Expansion Disorders

2017 ◽  
Author(s):  
Ankur Jain ◽  
Ronald D. Vale
Keyword(s):  
Rna Binding ◽  
Rna Binding Proteins ◽  
Neuromuscular Disorders ◽  
Cag Repeats ◽  
Live Cells ◽  
Critical Threshold ◽  
Rna Foci ◽  
Repeat Expansions ◽  
Nucleotide Repeats

Expansions of short nucleotide repeats in the protein coding and non-coding regions of >30 genes produce a variety of neurological and neuromuscular disorders including Huntington’s disease (CAG repeats), muscular dystrophy (CTG repeats) and amyotrophic lateral sclerosis (GGGGCC repeats) [1-3]. Expression of expanded repeats alone is sufficient to recapitulate disease pathology in animal models [4-6]. Repeat-containing transcripts accumulate in the nucleus as aberrant “RNA foci” [7-10] and sequester numerous RNA binding proteins [11,12], leading to a disruption of cellular homeostasis [13,14]. Interestingly, RNA foci, as well as the disease symptoms, only manifest at a critical threshold of nucleotide repeats: >30 for CAG/CTG expansions [1] and >7 for the GGGGCC expansion [15]. However, the reason for this characteristic threshold, as well as the molecular mechanism of foci formation, remain unresolved [16]. Here, we show that nucleotide repeat expansions in RNA create templates for multivalent Watson-Crick (CAG/CUG expansions) or Hoogsteen (GGGGCC expansion) base-pairing. These multivalent interactions cause purified RNAs containing repeat expansions to undergo a sol-gel transition and form micron-sized clusters. Reflecting an increase in the valency for intermolecular hybridization, the gelation of purified RNA only occurs above a critical number of trinucleotide or hexanucleotide repeats. These thresholds for in vitro RNA gelation are similar to those associated with manifestation of disease. By visualizing RNA in live cells, we show that nuclear foci form as a result of phase separation of the repeat-containing RNA and that these foci can be dissolved by agents that disrupt RNA gelation in vitro. Analogous to protein aggregation disorders, our results suggest that the sequence-specific gelation of RNAs could be a contributing factor to neurological disease.

scholarly journals Structure, dynamics and functions of UBQLNs: at the crossroads of protein quality control machinery

2020 ◽  
Vol 477 (18) ◽  
pp. 3471-3497 ◽  
Author(s):  
Tongyin Zheng ◽  
Yiran Yang ◽  
Carlos A. Castañeda
Keyword(s):  
Quality Control ◽  
Rna Binding ◽  
Protein Quality ◽  
Rna Binding Proteins ◽  
Protein Quality Control ◽  
Ubiquitin Proteasome System ◽  
Protein Homeostasis ◽  
Intrinsically Disordered ◽  
Structure Dynamics ◽  
And Function

Cells rely on protein homeostasis to maintain proper biological functions. Dysregulation of protein homeostasis contributes to the pathogenesis of many neurodegenerative diseases and cancers. Ubiquilins (UBQLNs) are versatile proteins that engage with many components of protein quality control (PQC) machinery in cells. Disease-linked mutations of UBQLNs are most commonly associated with amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD), and other neurodegenerative disorders. UBQLNs play well-established roles in PQC processes, including facilitating degradation of substrates through the ubiquitin–proteasome system (UPS), autophagy, and endoplasmic-reticulum-associated protein degradation (ERAD) pathways. In addition, UBQLNs engage with chaperones to sequester, degrade, or assist repair of misfolded client proteins. Furthermore, UBQLNs regulate DNA damage repair mechanisms, interact with RNA-binding proteins (RBPs), and engage with cytoskeletal elements to regulate cell differentiation and development. Important to the myriad functions of UBQLNs are its multidomain architecture and ability to self-associate. UBQLNs are linked to numerous types of cellular puncta, including stress-induced biomolecular condensates, autophagosomes, aggresomes, and aggregates. In this review, we focus on deciphering how UBQLNs function on a molecular level. We examine the properties of oligomerization-driven interactions among the structured and intrinsically disordered segments of UBQLNs. These interactions, together with the knowledge from studies of disease-linked mutations, provide significant insights to UBQLN structure, dynamics and function.

RNA binding proteins and the pathological cascade in ALS/FTD neurodegeneration

2017 ◽  
Vol 9 (415) ◽  
pp. eaah5436 ◽  
Author(s):  
Daisuke Ito ◽  
Mami Hatano ◽  
Norihiro Suzuki
Keyword(s):  
Quality Control ◽  
Amyotrophic Lateral Sclerosis ◽  
Molecular Basis ◽  
Binding Proteins ◽  
Rna Binding ◽  
Protein Quality ◽  
Rna Binding Proteins ◽  
Therapeutic Strategies ◽  
Related Proteins ◽  
Lateral Sclerosis

Advanced genetic approaches have accelerated the identification of causative genes linked to the neurodegenerative diseases amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Most of the disease-related proteins encoded by these genes form aggregates in the cellular machineries that regulate RNA and protein quality control in cells. Cross-talk among the signaling pathways governing these machineries leads to pathological cascades mediated by the accumulation of mutant RNA binding proteins. We outline the molecular basis of ALS and FTD pathogenesis and discuss the prospects for therapeutic strategies to treat these diseases.

scholarly journals The ribosome-bound quality control complex remains associated to aberrant peptides during their proteasomal targeting and interacts with Tom1 to limit protein aggregation

2017 ◽  
Vol 28 (9) ◽  
pp. 1165-1176 ◽  
Author(s):  
Quentin Defenouillère ◽  
Abdelkader Namane ◽  
John Mouaikel ◽  
Alain Jacquier ◽  
Micheline Fromont-Racine
Keyword(s):  
Quality Control ◽  
Protein Aggregation ◽  
Ubiquitin Ligase ◽  
Protein Quality ◽  
Translation Termination ◽  
E3 Ubiquitin Ligase ◽  
Protein Quality Control ◽  
Control Mechanisms ◽  
Ubiquitin Ligase Activity ◽  
Control Complex

Protein quality control mechanisms eliminate defective polypeptides to ensure proteostasis and to avoid the toxicity of protein aggregates. In eukaryotes, the ribosome-bound quality control (RQC) complex detects aberrant nascent peptides that remain stalled in 60S ribosomal particles due to a dysfunction in translation termination. The RQC complex polyubiquitylates aberrant polypeptides and recruits a Cdc48 hexamer to extract them from 60S particles in order to escort them to the proteasome for degradation. Whereas the steps from stalled 60S recognition to aberrant peptide polyubiquitylation by the RQC complex have been described, the mechanism leading to proteasomal degradation of these defective translation products remains unknown. We show here that the RQC complex also exists as a ribosome-unbound complex during the escort of aberrant peptides to the proteasome. In addition, we identify a new partner of this light version of the RQC complex, the E3 ubiquitin ligase Tom1. Tom1 interacts with aberrant nascent peptides and is essential to limit their accumulation and aggregation in the absence of Rqc1; however, its E3 ubiquitin ligase activity is not required. Taken together, these results reveal new roles for Tom1 in protein quality control, aggregate prevention, and, therefore, proteostasis maintenance.

scholarly journals A Retrotranslocation Assay That Predicts Defective VCP/p97-Mediated Trafficking of a Retroviral Signal Peptide

mBio ◽  
2022 ◽  
Author(s):  
Poulami Das ◽  
Wendy Kaichun Xu ◽  
Amit Kumar Singh Gautam ◽  
Mary M. Lozano ◽  
Jaquelin P. Dudley
Keyword(s):  
Quality Control ◽  
Signal Peptide ◽  
Mouse Mammary Tumor Virus ◽  
Rna Binding ◽  
Protein Quality ◽  
Cellular Protein ◽  
Mammary Tumor Virus ◽  
Endoplasmic Reticulum Associated Degradation ◽  
Mouse Mammary Tumor ◽  
Tumor Virus

Endoplasmic reticulum-associated degradation (ERAD) is a form of cellular protein quality control that is manipulated by viruses, including the betaretrovirus, mouse mammary tumor virus (MMTV). MMTV-encoded signal peptide (SP) has been shown to interact with an essential ERAD factor, VCP/p97 ATPase, to mediate its extraction from the ER membrane, also known as retrotranslocation, for RNA binding and nuclear function.

scholarly journals Mitochondrial antiviral-signalling protein is a client of the BAG6 protein quality control complex

2021 ◽  
Author(s):  
Peristera Roboti ◽  
Craig Lawless ◽  
Stephen High
Keyword(s):  
Quality Control ◽  
Cellular Response ◽  
Protein Quality ◽  
Protein Quality Control ◽  
Innate Immune ◽  
Control Factor ◽  
Stable Complex ◽  
Summary Statement ◽  
Ta Proteins ◽  
Control Complex

ABSTRACTThe heterotrimeric BAG6 complex coordinates the direct handover of newly synthesised tail-anchored (TA) membrane proteins from an SGTA-bound preloading complex to the endoplasmic reticulum (ER) delivery component TRC40. In contrast, defective precursors, including aberrant TA proteins, form a stable complex with this cytosolic protein quality control factor, enabling such clients to be either productively re-routed or selectively degraded. We identify the mitochondrial TA protein MAVS (mitochondrial antiviral-signalling protein) as an endogenous client of both SGTA and the BAG6 complex. Our data suggest that the BAG6 complex binds to a cytosolic pool of MAVS before its misinsertion into the ER membrane, from where it can subsequently be removed via ATP13A1-mediated dislocation. This BAG6- associated fraction of MAVS is dynamic and responds to the activation of an innate immune response, suggesting that BAG6 may modulate the pool of MAVS that is available for coordinating the cellular response to viral infection.SUMMARY STATEMENTMitochondrial antiviral-signalling (MAVS) protein is a favoured client of the cytosolic BAG6 complex. We discuss how this dynamic interaction may modulate MAVS biogenesis at signalling membranes.

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