scholarly journals Breakdown of Filamentous Myofibrils by the UPS–Step by Step

Biomolecules ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 110
Author(s):  
Dina Aweida ◽  
Shenhav Cohen
Keyword(s):  
Protein Quality ◽  
Protein Structures ◽  
Ubiquitin Proteasome System ◽  
Surface Proteins ◽  
Catalytic Core ◽  
Complex Protein ◽  
Ubiquitin Proteasome ◽  
Aaa Atpases

Protein degradation maintains cellular integrity by regulating virtually all biological processes, whereas impaired proteolysis perturbs protein quality control, and often leads to human disease. Two major proteolytic systems are responsible for protein breakdown in all cells: autophagy, which facilitates the loss of organelles, protein aggregates, and cell surface proteins; and the ubiquitin-proteasome system (UPS), which promotes degradation of mainly soluble proteins. Recent findings indicate that more complex protein structures, such as filamentous assemblies, which are not accessible to the catalytic core of the proteasome in vitro, can be efficiently degraded by this proteolytic machinery in systemic catabolic states in vivo. Mechanisms that loosen the filamentous structure seem to be activated first, hence increasing the accessibility of protein constituents to the UPS. In this review, we will discuss the mechanisms underlying the disassembly and loss of the intricate insoluble filamentous myofibrils, which are responsible for muscle contraction, and whose degradation by the UPS causes weakness and disability in aging and disease. Several lines of evidence indicate that myofibril breakdown occurs in a strictly ordered and controlled manner, and the function of AAA-ATPases is crucial for their disassembly and loss.

Degradation of mutant huntingtin via the ubiquitin/proteasome system is modulated by FE65

2012 ◽  
Vol 443 (3) ◽  
pp. 681-689 ◽  
Author(s):  
Wan Ning Vanessa Chow ◽  
Hon Wing Luk ◽  
Ho Yin Edwin Chan ◽  
Kwok-Fai Lau
Keyword(s):  
Cell Death ◽  
Degradation Mechanism ◽  
Neuronal Cell Death ◽  
Neuronal Cell ◽  
Adaptor Protein ◽  
Ubiquitin Proteasome System ◽  
Exon 1 ◽  
Ubiquitin Proteasome

An unstable expansion of the polyglutamine repeat within exon 1 of the protein Htt (huntingtin) causes HD (Huntington's disease). Mounting evidence shows that accumulation of N-terminal mutant Htt fragments is the source of disruption of normal cellular processes which ultimately leads to neuronal cell death. Understanding the degradation mechanism of mutant Htt and improving its clearance has emerged as a new direction in developing therapeutic approaches to treat HD. In the present study we show that the brain-enriched adaptor protein FE65 is a novel interacting partner of Htt. The binding is mediated through WW–polyproline interaction and is dependent on the length of the polyglutamine tract. Interestingly, a reduction in mutant Htt protein level was observed in FE65-knockdown cells, and the process requires the UPS (ubiquitin/proteasome system). Moreover, the ubiquitination level of mutant Htt was found to be enhanced when FE65 is knocked down. Immunofluroescence staining revealed that FE65 associates with mutant Htt aggregates. Additionally, we demonstrated that overexpression of FE65 increases mutant Htt-induced cell death both in vitro and in vivo. These results suggest that FE65 facilitates the accumulation of mutant Htt in cells by preventing its degradation via the UPS, and thereby enhances the toxicity of mutant Htt.

scholarly journals Functional expression and localisation of HOPS/TMUB1 in mouse lens

2021 ◽  
Vol 41 (2) ◽  
Author(s):  
Daniela Bartoli ◽  
Danilo Piobbico ◽  
Marilena Castelli ◽  
Stefania Pieroni ◽  
Damiano Scopetti ◽  
...  
Keyword(s):  
Ubiquitin Proteasome System ◽  
Functional Expression ◽  
Transitional Zone ◽  
Structural Function ◽  
Ubiquitin Proteasome ◽  
Lens Cell ◽  
Mouse Lens ◽  
Functional Phenotype

Abstract Transparency represents the functional phenotype of eye lens. A number of defined steps including quiescence, proliferation, migration and cell differentiation culminates in cell elongation and organelle degradation, allowing the light to reach the retina. HOPS (Hepatocyte Odd Protein Shuttling)/TMUB1 (Trans Membrane Ubiquitin-like containing protein 1) is a nucleo-cytoplasmic shuttling protein, highly expressed both in vivo and in vitro proliferating systems, bearing a ubiquitin-like domain. The present study shows HOPS expression during the phases of lens cell proliferation and fiber differentiation, and its localisation in lens compartments. In lens, HOPS localises mainly in the nucleus of central epithelial cells. During mitosis, HOPS/TMUB1 shuttles to the cytoplasm and returns to the nucleus at the end of mitosis. The differentiating cells share distinct HOPS/TMUB1 localisation in transitional zone depending on the differentiation phases. HOPS/TMUB1 is observed in lens cortex and nucleus. Here, it is attached to fibers, having a structural function with crystallin proteins, probably acting in the ubiquitin–proteasome system.

scholarly journals Bifunctional Small Molecules That Mediate the Degradation of Extracellular Proteins

2020 ◽  
Author(s):  
David Caianiello ◽  
Mengwen Zhang ◽  
Jason Ray ◽  
Jake Swartzel ◽  
Emily Branham ◽  
...  
Keyword(s):  
Ubiquitin Proteasome System ◽  
Extracellular Proteins ◽  
Target Protein ◽  
Disease Treatment ◽  
Bifunctional Molecules ◽  
Synthetic Molecules ◽  
Ubiquitin Proteasome ◽  
Mode A

<p>Targeted protein degradation (TPD) has emerged as a promising and exciting therapeutic strategy. The majority of existing TPD technologies rely on the ubiquitin-proteasome system, and are therefore limited to targeting intracellular proteins. To address this limitation, we developed a class of modularly designed, bifunctional synthetic molecules called <b>MoDE-A</b>s (<b>Mo</b>lecular <b>D</b>egraders of <b>E</b>xtracellular proteins through the <b>A</b>sialoglycoprotein receptor (ASGPR)), which are capable of mediating the degradation of extracellular proteins. MoDE-A molecules mediate the formation of a ternary complex between a target protein and the ASGPR, which is expressed primarily on hepatocytes. The target protein is then endocytosed and degraded by lysosomal proteases. We demonstrated the modularity of the MoDE-A technology by synthesizing bifunctional molecules that induce the degradation of both antibody and pro-inflammatory cytokine proteins. To our knowledge, these data represent the first experimental evidence that non-proteinogenic, synthetic molecules can be employed for the TPD of extracellular proteins both <i>in vitro</i> and <i>in vivo</i>. We believe that TPD mediated by the MoDE-A technology will have widespread applications for disease treatment.</p>

scholarly journals A Conditional Yeast E1 Mutant Blocks the Ubiquitin–Proteasome Pathway and Reveals a Role for Ubiquitin Conjugates in Targeting Rad23 to the Proteasome

2007 ◽  
Vol 18 (5) ◽  
pp. 1953-1963 ◽  
Author(s):  
Nazli Ghaboosi ◽  
Raymond J. Deshaies
Keyword(s):  
Initial Step ◽  
Adaptor Proteins ◽  
Ubiquitin Proteasome System ◽  
Temperature Sensitive ◽  
Polyubiquitin Chains ◽  
Multiple Substrates ◽  
Ubiquitin Proteasome ◽  
Sensitive Allele

E1 ubiquitin activating enzyme catalyzes the initial step in all ubiquitin-dependent processes. We report the isolation of uba1-204, a temperature-sensitive allele of the essential Saccharomyces cerevisiae E1 gene, UBA1. Uba1-204 cells exhibit dramatic inhibition of the ubiquitin–proteasome system, resulting in rapid depletion of cellular ubiquitin conjugates and stabilization of multiple substrates. We have employed the tight phenotype of this mutant to investigate the role ubiquitin conjugates play in the dynamic interaction of the UbL/UBA adaptor proteins Rad23 and Dsk2 with the proteasome. Although proteasomes purified from mutant cells are intact and proteolytically active, they are depleted of ubiquitin conjugates, Rad23, and Dsk2. Binding of Rad23 to these proteasomes in vitro is enhanced by addition of either free or substrate-linked ubiquitin chains. Moreover, association of Rad23 with proteasomes in mutant and wild-type cells is improved upon stabilizing ubiquitin conjugates with proteasome inhibitor. We propose that recognition of polyubiquitin chains by Rad23 promotes its shuttling to the proteasome in vivo.

scholarly journals β-TrCP-mediated ubiquitination and degradation of Dlg5 regulates hepatocellular carcinoma cell proliferation

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Dongping Wang ◽  
Qi Zhang ◽  
Fenfen Li ◽  
Chan Wang ◽  
Changming Yang ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Xenograft Model ◽  
Ubiquitin Proteasome System ◽  
Tumor Xenograft ◽  
Dependent Manner ◽  
Ubiquitin Proteasome ◽  
Novel Strategy ◽  
Hcc Cells

Abstract Background Discs large homolog 5 (Dlg5) is a member of the membrane-associated guanylate kinase (MAGUK) adaptor family of proteins and its deregulation has been implicated in the malignancy of several cancer types. Dlg5 was down-regulated in hepatocellular carcinoma (HCC) and lower Dlg5 expression was associated with poor survival of HCC patients. However, how to regulate Dlg5 remains largely unknown. Methods The co-immunoprecipitation assay was used to determine the interaction between Dlg5 and β-TrCP. The in vivo ubiquitination assay was performed to determine the regulation of Dlg5 by β-TrCP. CCK-8 and colony formation assay were implemented to detect the biological effect of Dlg5 on the growth of HCC cells in vitro. The effect of Dlg5 on HCC tumor growth in vivo was studied in a tumor xenograft model in mice. Results Here we report that Dlg5 is regulated by the ubiquitin proteasome system and depletion of either Cullin 1 or β-TrCP led to increased levels of Dlg5. β-TrCP regulated Dlg5 protein stability by targeting it for ubiquitination and subsequent destruction in a phosphorylation-dependent manner. We further demonstrated a crucial role of Ser730 in the non-canonical phosphodegron of Dlg5 in governing β-TrCP-mediated Dlg5 degradation. Importantly, failure to degrade Dlg5 significantly inhibited HCC cells proliferation both in vitro and in vivo. Conclusion Collectively, our finding provides a novel molecular mechanism for the negative regulation of Dlg5 by β-TRCP in HCC cells. It further suggests that preventing Dlg5 degradation could be a possible novel strategy for clinical treatment of HCC.

scholarly journals Structural and functional characterization of Rpn12 identifies residues required for Rpn10 proteasome incorporation

2012 ◽  
Vol 448 (1) ◽  
pp. 55-65 ◽  
Author(s):  
Jonas Boehringer ◽  
Christiane Riedinger ◽  
Konstantinos Paraskevopoulos ◽  
Eachan O. D. Johnson ◽  
Edward D. Lowe ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Functional Characterization ◽  
Ubiquitin Proteasome System ◽  
26S Proteasome ◽  
Structural Motif ◽  
Protein Protein Interactions ◽  
Ubiquitin Proteasome

The ubiquitin–proteasome system targets selected proteins for degradation by the 26S proteasome. Rpn12 is an essential component of the 19S regulatory particle and plays a role in recruiting the extrinsic ubiquitin receptor Rpn10. In the present paper we report the crystal structure of Rpn12, a proteasomal PCI-domain-containing protein. The structure helps to define a core structural motif for the PCI domain and identifies potential sites through which Rpn12 might form protein–protein interactions. We demonstrate that mutating residues at one of these sites impairs Rpn12 binding to Rpn10 in vitro and reduces Rpn10 incorporation into proteasomes in vivo.

scholarly journals Amyloid Precursor Protein (APP) May Act as a Substrate and a Recognition Unit for CRL4CRBN and Stub1 E3 Ligases Facilitating Ubiquitination of Proteins Involved in Presynaptic Functions and Neurodegeneration

2016 ◽  
Vol 291 (33) ◽  
pp. 17209-17227 ◽  
Author(s):  
Dolores Del Prete ◽  
Richard C. Rice ◽  
Anjali M. Rajadhyaksha ◽  
Luciano D'Adamio
Keyword(s):  
Amyloid Precursor Protein ◽  
Transmitter Release ◽  
Ubiquitin Proteasome System ◽  
Precursor Protein ◽  
E3 Ligases ◽  
Ubiquitin Proteasome ◽  
Functional Pathway ◽  
Related Proteins

The amyloid precursor protein (APP), whose mutations cause Alzheimer disease, plays an important in vivo role and facilitates transmitter release. Because the APP cytosolic region (ACR) is essential for these functions, we have characterized its brain interactome. We found that the ACR interacts with proteins that regulate the ubiquitin-proteasome system, predominantly with the E3 ubiquitin-protein ligases Stub1, which binds the NH2 terminus of the ACR, and CRL4CRBN, which is formed by Cul4a/b, Ddb1, and Crbn, and interacts with the COOH terminus of the ACR via Crbn. APP shares essential functions with APP-like protein-2 (APLP2) but not APP-like protein-1 (APLP1). Noteworthy, APLP2, but not APLP1, interacts with Stub1 and CRL4CRBN, pointing to a functional pathway shared only by APP and APLP2. In vitro ubiquitination/ubiquitome analysis indicates that these E3 ligases are enzymatically active and ubiquitinate the ACR residues Lys649/650/651/676/688. Deletion of Crbn reduces ubiquitination of Lys676 suggesting that Lys676 is physiologically ubiquitinated by CRL4CRBN. The ACR facilitated in vitro ubiquitination of presynaptic proteins that regulate exocytosis, suggesting a mechanism by which APP tunes transmitter release. Other dementia-related proteins, namely Tau and apoE, interact with and are ubiquitinated via the ACR in vitro. This, and the evidence that CRBN and CUL4B are linked to intellectual disability, prompts us to hypothesize a pathogenic mechanism, in which APP acts as a modulator of E3 ubiquitin-protein ligase(s), shared by distinct neuronal disorders. The well described accumulation of ubiquitinated protein inclusions in neurodegenerative diseases and the link between the ubiquitin-proteasome system and neurodegeneration make this concept plausible.

Fas expression promotes proteasomal activity in toxin-induced parkinsonism

2012 ◽  
Vol 24 (3) ◽  
pp. 166-171
Author(s):  
Anne M. Landau ◽  
Rosmarie Siegrist-Johnstone ◽  
Julie Desbarats
Keyword(s):  
Neuroblastoma Cells ◽  
Death Receptor ◽  
Protein Aggregates ◽  
Ubiquitin Proteasome System ◽  
Wild Type ◽  
Proteasomal Activity ◽  
Ubiquitin Proteasome ◽  
Deficient Mice

Objective: Fas (CD95), commonly categorised as a death receptor due to its well-defined role in apoptosis, can paradoxically also promote neuroprotection. We have previously found that defects in Fas signalling render mice highly susceptible to neural degeneration in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine mouse model of Parkinson's disease (PD). Decreased activity of the ubiquitin proteasome system and accumulation of protein aggregates are implicated in PD pathogenesis. Here, we investigate the relationship between Fas and ubiquitin proteasomal activity in neuronal cells.Methods: We performed proteasome assays in neuroblastoma cells and in midbrain cultures of wild-type and Fas-deficient mice.Results: Neuroblastoma cells upregulated proteasomal activity in response to an activating Fas antibody in vitro. Furthermore, neural tissue from Fas-deficient mice showed decreased proteasomal activity compared with the tissue from wild-type mice when exposed to a PD-inducing toxin in vivo.Conclusion: These findings suggest that mechanisms for Fas-mediated neuroprotection may include Fas-induced upregulation of proteasomal activity, and consequently less accumulation of toxic protein aggregates.

Protein Quality Control of the Endoplasmic Reticulum and Ubiquitin–Proteasome-Triggered Degradation of Aberrant Proteins: Yeast Pioneers the Path

2018 ◽  
Vol 87 (1) ◽  
pp. 751-782 ◽  
Author(s):  
Nicole Berner ◽  
Karl-Richard Reutter ◽  
Dieter H. Wolf
Keyword(s):  
Quality Control ◽  
Endoplasmic Reticulum ◽  
Protein Quality ◽  
Protein Structures ◽  
Protein Quality Control ◽  
Ubiquitin Proteasome System ◽  
Misfolded Proteins ◽  
Secretory Proteins ◽  
Structural Alterations ◽  
Ubiquitin Proteasome

Cells must constantly monitor the integrity of their macromolecular constituents. Proteins are the most versatile class of macromolecules but are sensitive to structural alterations. Misfolded or otherwise aberrant protein structures lead to dysfunction and finally aggregation. Their presence is linked to aging and a plethora of severe human diseases. Thus, misfolded proteins have to be rapidly eliminated. Secretory proteins constitute more than one-third of the eukaryotic proteome. They are imported into the endoplasmic reticulum (ER), where they are folded and modified. A highly elaborated machinery controls their folding, recognizes aberrant folding states, and retrotranslocates permanently misfolded proteins from the ER back to the cytosol. In the cytosol, they are degraded by the highly selective ubiquitin–proteasome system. This process of protein quality control followed by proteasomal elimination of the misfolded protein is termed ER-associated degradation (ERAD), and it depends on an intricate interplay between the ER and the cytosol.

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