scholarly journals TNF receptor associated factor 6 interacts with ALS-linked misfolded superoxide dismutase 1 and promotes aggregation

2019 ◽  
Author(s):  
Sabrina Semmler ◽  
Myriam Gagné ◽  
Pranav Garg ◽  
Sarah Pickles ◽  
Charlotte Baudouin ◽  
...  
Keyword(s):  
Superoxide Dismutase ◽  
Motor Neurons ◽  
Ubiquitin Ligase ◽  
Protein Misfolding ◽  
E3 Ubiquitin Ligase ◽  
Tnf Receptor ◽  
Gene Encoding ◽  
Associated Factor ◽  
Independent Events ◽  
Misfolded Sod1

ABSTRACTAmyotrophic lateral sclerosis (ALS) is a fatal disease, characterized by the selective loss of motor neurons leading to paralysis. Mutations in the gene encoding superoxide dismutase 1 (SOD1) are the second most common cause of familial ALS, and considerable evidence suggests that these mutations result in an increase in toxicity due to protein misfolding. We previously demonstrated in the SOD1G93A rat model that misfolded SOD1 exists as distinct conformers and forms deposits on mitochondrial subpopulations. Here, using SOD1G93A rats and conformation-restricted antibodies specific for misfolded SOD1 (B8H10 and AMF7-63), we identified the interactomes of the mitochondrial pools of misfolded SOD1. This strategy identified binding proteins that uniquely interacted with either AMF7-63 or B8H10-reactive SOD1 conformers as well as with a high proportion of interactors common to both conformers. Of this latter set, we identified the E3 ubiquitin ligase TNF receptor-associated factor 6 (TRAF6) as a SOD1 interactor and determined that exposure of the SOD1 functional loops facilitates this interaction. Of note, this conformational change was not universally fulfilled by all SOD1 variants and differentiated TRAF6-interacting from TRAF6 non-interacting SOD1 variants. Functionally, TRAF6 stimulated polyubiquitination and aggregation of the interacting SOD1 variants. TRAF6 E3 ubiquitin ligase activity was required for the former, but was dispensable for the latter, indicating that TRAF6-mediated polyubiquitination and aggregation of the SOD1 variants are independent events. We propose that the interaction between misfolded SOD1 and TRAF6 may be relevant to the etiology of ALS.

scholarly journals TNF receptor–associated factor 6 interacts with ALS-linked misfolded superoxide dismutase 1 and promotes aggregation

2020 ◽  
Vol 295 (12) ◽  
pp. 3808-3825 ◽  
Author(s):  
Sabrina Semmler ◽  
Myriam Gagné ◽  
Pranav Garg ◽  
Sarah R. Pickles ◽  
Charlotte Baudouin ◽  
...  
Keyword(s):  
Superoxide Dismutase ◽  
Motor Neurons ◽  
Ubiquitin Ligase ◽  
Protein Misfolding ◽  
E3 Ubiquitin Ligase ◽  
Tnf Receptor ◽  
Superoxide Dismutase 1 ◽  
Associated Factor ◽  
Independent Events ◽  
Misfolded Sod1

Amyotrophic lateral sclerosis (ALS) is a fatal disease, characterized by the selective loss of motor neurons leading to paralysis. Mutations in the gene encoding superoxide dismutase 1 (SOD1) are the second most common cause of familial ALS, and considerable evidence suggests that these mutations result in an increase in toxicity due to protein misfolding. We previously demonstrated in the SOD1G93A rat model that misfolded SOD1 exists as distinct conformers and forms deposits on mitochondrial subpopulations. Here, using SOD1G93A rats and conformation-restricted antibodies specific for misfolded SOD1 (B8H10 and AMF7-63), we identified the interactomes of the mitochondrial pools of misfolded SOD1. This strategy identified binding proteins that uniquely interacted with either AMF7-63 or B8H10-reactive SOD1 conformers as well as a high proportion of interactors common to both conformers. Of this latter set, we identified the E3 ubiquitin ligase TNF receptor–associated factor 6 (TRAF6) as a SOD1 interactor, and we determined that exposure of the SOD1 functional loops facilitates this interaction. Of note, this conformational change was not universally fulfilled by all SOD1 variants and differentiated TRAF6 interacting from TRAF6 noninteracting SOD1 variants. Functionally, TRAF6 stimulated polyubiquitination and aggregation of the interacting SOD1 variants. TRAF6 E3 ubiquitin ligase activity was required for the former but was dispensable for the latter, indicating that TRAF6-mediated polyubiquitination and aggregation of the SOD1 variants are independent events. We propose that the interaction between misfolded SOD1 and TRAF6 may be relevant to the etiology of ALS.

Abstract 18: Synoviolin, an E3 Ubiquitin Ligase, Modulates Cardiac Myocyte Size and Restores Heart Function in Hypertrophic Cardiomyopathy

2012 ◽  
Vol 111 (suppl_1) ◽  
Author(s):  
Shirin Doroudgar ◽  
Mirko Völkers ◽  
Donna J Thuerauf ◽  
Ashley Bumbar ◽  
Mohsin Khan ◽  
...  
Keyword(s):  
Ubiquitin Ligase ◽  
Protein Misfolding ◽  
Cardiac Myocyte ◽  
Protein Quality ◽  
Heart Function ◽  
E3 Ubiquitin Ligase ◽  
Ubiquitin Ligases ◽  
Calcium Handling ◽  
Loss Of Function

The endoplasmic reticulum (ER) is essential for protein homeostasis, or proteostasis, which governs the balance of the proteome. In addition to secreted and membrane proteins, proteins bound for many other cellular locations are also made on ER-bound ribosomes, emphasizing the importance of protein quality and quantity control in the ER. Unlike cytosolic E3 ubiquitin ligases studied in the heart, synoviolin/Hrd1, which has not been studied in the heart, is an ER transmembrane E3 ubiquitin ligase, which we found to be upregulated upon protein misfolding in cardiac myocytes. Given the strategic location of synoviolin in the ER membrane, we addressed the hypothesis that synoviolin is critical for regulating the balance of the proteome, and accordingly, myocyte size. We showed that in vitro, adenovirus-mediated overexpression of synoviolin decreased cardiac myocyte size and protein synthesis, but unlike atrophy-related ubiquitin ligases, synoviolin did not increase global protein degradation. Furthermore, targeted gene therapy using adeno-associated virus 9 (AAV9) showed that overexpression of synoviolin in the left ventricle attenuated maladaptive cardiac hypertrophy and preserved cardiac function in mice subjected to trans-aortic constriction (AAV9-control TAC = 22.5 ± 6.2% decrease in EF vs. AAV9-synoviolin TAC at 6 weeks post TAC; P<0.001), and decreased mTOR activity. Since calcium is a major regulator of cardiac myocyte size, we examined the effects of synoviolin gain- or loss-of-function, using AAV9-synoviolin, or an miRNA designed to knock down synoviolin, respectively. While synoviolin gain-of-function did not affect calcium handling in isolated adult myocytes, synoviolin loss-of-function increased calcium transient amplitude (P<0.01), prolonged spark duration (P<0.001), and increased spark width (P<0.001). Spark frequency and amplitude were unaltered upon synoviolin gain- or loss-of-function. Whereas SR calcium load was unaltered by synoviolin loss-of-function, SERCA-mediated calcium removal was reduced (P<0.05). In conclusion, our studies suggest that in the heart, synoviolin is 1) a critical component of proteostasis, 2) a novel determinant of cardiac myocyte size, and 3) necessary for proper calcium handling.

Mutational analysis of UBR5 gene encoding an E3 ubiquitin ligase in common human cancers

Pathology ◽  
2010 ◽  
Vol 42 (1) ◽  
pp. 93-94 ◽  
Author(s):  
Min Sung Kim ◽  
Ji Eun Oh ◽  
Hyeon Seok Eom ◽  
Nam Jin Yoo ◽  
Sug Hyung Lee
Keyword(s):  
Ubiquitin Ligase ◽  
Mutational Analysis ◽  
E3 Ubiquitin Ligase ◽  
Gene Encoding ◽  
Human Cancers

scholarly journals The E3 ubiquitin ligase MID1/TRIM18 promotes atypical ubiquitination of the BRCA2-associated factor 35, BRAF35

2017 ◽  
Vol 1864 (10) ◽  
pp. 1844-1854 ◽  
Author(s):  
Melania E. Zanchetta ◽  
Luisa M.R. Napolitano ◽  
Danilo Maddalo ◽  
Germana Meroni
Keyword(s):  
Ubiquitin Ligase ◽  
E3 Ubiquitin Ligase ◽  
Associated Factor

scholarly journals Ubiquitin systems mark pathogen-containing vacuoles as targets for host defense by guanylate binding proteins

2015 ◽  
Vol 112 (41) ◽  
pp. E5628-E5637 ◽  
Author(s):  
Arun K. Haldar ◽  
Clémence Foltz ◽  
Ryan Finethy ◽  
Anthony S. Piro ◽  
Eric M. Feeley ◽  
...  
Keyword(s):  
Ubiquitin Ligase ◽  
Microbial Growth ◽  
E3 Ubiquitin Ligase ◽  
Host Cells ◽  
Tnf Receptor ◽  
Host Proteins ◽  
Growth And Survival ◽  
Guanylate Binding Protein ◽  
Rhoptry Protein ◽  
Necrosis Factor

Many microbes create and maintain pathogen-containing vacuoles (PVs) as an intracellular niche permissive for microbial growth and survival. The destruction of PVs by IFNγ-inducible guanylate binding protein (GBP) and immunity-related GTPase (IRG) host proteins is central to a successful immune response directed against numerous PV-resident pathogens. However, the mechanism by which IRGs and GBPs cooperatively detect and destroy PVs is unclear. We find that host cell priming with IFNγ prompts IRG-dependent association of Toxoplasma- and Chlamydia-containing vacuoles with ubiquitin through regulated translocation of the E3 ubiquitin ligase tumor necrosis factor (TNF) receptor associated factor 6 (TRAF6). This initial ubiquitin labeling elicits p62-mediated escort and deposition of GBPs to PVs, thereby conferring cell-autonomous immunity. Hypervirulent strains of Toxoplasma gondii evade this process via specific rhoptry protein kinases that inhibit IRG function, resulting in blockage of downstream PV ubiquitination and GBP delivery. Our results define a ubiquitin-centered mechanism by which host cells deliver GBPs to PVs and explain how hypervirulent parasites evade GBP-mediated immunity.

scholarly journals New Discoveries on the Roles of “Other” HECT E3 Ubiquitin Ligases in Disease Development

2020 ◽  
Author(s):  
Emma I. Kane ◽  
Donald E. Spratt
Keyword(s):  
Ubiquitin Ligase ◽  
Developmental Disorders ◽  
E3 Ubiquitin Ligase ◽  
Ubiquitin Ligases ◽  
Disease Development ◽  
E3 Ubiquitin Ligases ◽  
Gene Encoding ◽  
Family Function ◽  
Substrate Proteins ◽  
Comprehensive Discussion

HECT E3 ubiquitin ligases selectively recognize, bind, and ubiquitylate their substrate proteins to target them for 26S proteasomal degradation. There is increasing evidence that HECT E3 ubiquitin ligase dysfunction due to misfolding and/or the gene encoding the protein being mutated is responsible for the development of different diseases. Apart from the more prominent and well-characterized E6AP and members of the NEDD4 family, new studies have begun to reveal how other members of the HECT E3 ubiquitin ligase family function as well as their links to disease and developmental disorders. This chapter provides a comprehensive discussion on the more mysterious members of the HECT E3 ubiquitin ligase family and how they control intracellular processes. Specifically, AREL1, HACE1, HECTD1, HECTD4, G2E3, and TRIP12 will be examined as these enzymes have recently been identified as contributors to disease development.

scholarly journals Huntingtin Ubiquitination Mechanisms and Novel Possible Therapies to Decrease the Toxic Effects of Mutated Huntingtin

2021 ◽  
Vol 11 (12) ◽  
pp. 1309
Author(s):  
Annarita Fiorillo ◽  
Veronica Morea ◽  
Gianni Colotti ◽  
Andrea Ilari
Keyword(s):  
Small Molecules ◽  
Ubiquitin Ligase ◽  
Neurodegenerative Disorder ◽  
E3 Ubiquitin Ligase ◽  
Ubiquitin Proteasome System ◽  
Aggregate Formation ◽  
Gene Encoding ◽  
Exon 1 ◽  
Ubiquitin Proteasome ◽  
Abnormal Expansion

Huntington Disease (HD) is a dominant, lethal neurodegenerative disorder caused by the abnormal expansion (>35 copies) of a CAG triplet located in exon 1 of the HTT gene encoding the huntingtin protein (Htt). Mutated Htt (mHtt) easily aggregates, thereby inducing ER stress that in turn leads to neuronal injury and apoptosis. Therefore, both the inhibition of mHtt aggregate formation and the acceleration of mHtt degradation represent attractive strategies to delay HD progression, and even for HD treatment. Here, we describe the mechanism underlying mHtt degradation by the ubiquitin–proteasome system (UPS), which has been shown to play a more important role than the autophagy–lysosomal pathway. In particular, we focus on E3 ligase proteins involved in the UPS and detail their structure–function relationships. In this framework, we discuss the possible exploitation of PROteolysis TArgeting Chimeras (PROTACs) for HD therapy. PROTACs are heterobifunctional small molecules that comprise two different ligands joined by an appropriate linker; one of the ligands is specific for a selected E3 ubiquitin ligase, the other ligand is able to recruit a target protein of interest, in this case mHtt. As a consequence of PROTAC binding, mHtt and the E3 ubiquitin ligase can be brought to a relative position that allows mHtt to be ubiquitinated and, ultimately, allows a reduction in the amount of mHtt in the cell.

scholarly journals Hypoxia-Associated Factor, a Novel E3-Ubiquitin Ligase, Binds and Ubiquitinates Hypoxia-Inducible Factor 1α, Leading to Its Oxygen-Independent Degradation

2008 ◽  
Vol 28 (23) ◽  
pp. 7081-7095 ◽  
Author(s):  
Mei Yee Koh ◽  
Bryant G. Darnay ◽  
Garth Powis
Keyword(s):  
Ubiquitin Ligase ◽  
Cellular Response ◽  
Hypoxia Inducible Factor ◽  
E3 Ubiquitin Ligase ◽  
Degradation Pathway ◽  
Proliferating Cells ◽  
Associated Factor ◽  
Hypoxia Inducible Factor 1Α

ABSTRACT The hypoxia-inducible factor 1α (HIF-1α) is the master regulator of the cellular response to hypoxia. A key regulator of HIF-1α is von Hippel-Lindau protein (pVHL), which mediates the oxygen-dependent, proteasomal degradation of HIF-1α in normoxia. Here, we describe a new regulator of HIF-1α, the hypoxia-associated factor (HAF), a novel E3-ubiquitin ligase that binds HIF-1α leading to its proteasome-dependent degradation irrespective of cellular oxygen tension. HAF, a protein expressed in proliferating cells, binds and ubiquitinates HIF-1α in vitro, and both binding and E3 ligase activity are mediated by HAF amino acids 654 to 800. Furthermore, HAF overexpression decreases HIF-1α levels in normoxia and hypoxia in both pVHL-competent and -deficient cells, whereas HAF knockdown increases HIF-1α levels in normoxia, hypoxia, and under epidermal growth factor stimulation. In contrast, HIF-2α is not regulated by HAF. In vivo, tumor xenografts from cells overexpressing HAF show decreased levels of HIF-1α accompanied by decreased tumor growth and angiogenesis. Therefore, HAF is the key mediator of a new HIF-1α-specific degradation pathway that degrades HIF-1α through a new, oxygen-independent mechanism.

scholarly journals Effects of maturation on the conformational free-energy landscape of SOD1

2018 ◽  
Vol 115 (11) ◽  
pp. E2546-E2555 ◽  
Author(s):  
Robert M. Culik ◽  
Ashok Sekhar ◽  
Jayashree Nagesh ◽  
Harmeen Deol ◽  
Jessica A. O. Rumfeldt ◽  
...  
Keyword(s):  
Free Energy ◽  
Motor Neurons ◽  
Disulfide Bond ◽  
Posttranslational Modifications ◽  
Protein Misfolding ◽  
Metal Loss ◽  
Free Energy Surface ◽  
Switch Mechanism ◽  
Misfolded Sod1

Amyotrophic lateral sclerosis (ALS) is a devastating fatal syndrome characterized by very rapid degeneration of motor neurons. A leading hypothesis is that ALS is caused by toxic protein misfolding and aggregation, as also occurs in many other neurodegenerative disorders, such as prion, Alzheimer’s, Parkinson’s, and Huntington’s diseases. A prominent cause of familial ALS is mutations in the protein superoxide dismutase (SOD1), which promote the formation of misfolded SOD1 conformers that are prone to aberrant interactions both with each other and with other cellular components. We have shown previously that immature SOD1, lacking bound Cu and Zn metal ions and the intrasubunit disulfide bond (apoSOD12SH), has a rugged free-energy surface (FES) and exchanges with four other conformations (excited states) that have millisecond lifetimes and sparse populations on the order of a few percent. Here, we examine further states of SOD1 along its maturation pathway, as well as those off-pathway resulting from metal loss that have been observed in proteinaceous inclusions. Metallation and disulfide bond formation lead to structural transformations including local ordering of the electrostatic loop and native dimerization that are observed in rare conformers of apoSOD12SH; thus, SOD1 maturation may occur via a population-switch mechanism whereby posttranslational modifications select for preexisting structures on the FES. Metallation and oxidation of SOD1 stabilize the native, mature conformation and decrease the number of detected excited conformational states, suggesting that it is the immature forms of the protein that contribute to misfolded conformations in vivo rather than the highly stable enzymatically active dimer.

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