Abstract 85: The AAA-ATPase p97 is a Critical Regulator of Cardiac Homeostasis

2017 ◽  
Vol 121 (suppl_1) ◽  
Author(s):  
Matthew J Brody ◽  
Michelle A Sargent ◽  
Jeffery D Molkentin
Keyword(s):  
Quality Control ◽  
Protein Quality ◽  
Protein Complexes ◽  
Protein Quality Control ◽  
Ubiquitin Proteasome System ◽  
Cellular Protein ◽  
Dominant Negative ◽  
Aaa Atpase ◽  
And Function ◽  
Thrombospondin 4

p97 is a AAA-ATPase that plays critical roles in a myriad of cellular protein quality control processes, including the endoplasmic reticulum (ER)-associated degradation (ERAD) pathway that targets misfolded proteins in the ER for degradation in the cytosol by the ubiquitin proteasome system. Mutations in p97 cause a multisystem degenerative proteinopathy disorder called inclusion body myopathy with Paget disease of bone and frontotemporal dementia (IBMPFD) that includes pathologies of the nervous system, skeletal muscle, bone, and heart. Previous studies in the laboratory into the mechanisms whereby thrombospondin 4 has its cardioprotective effects and enhanced ERAD activity identified p97 as a direct interacting partner. This observation suggested that p97 itself could be an important cardioprotective effector by benefiting protein quality control in the heart. To address this hypothesis here we generated cardiac-specific transgenic mice overexpressing wildtype p97 or a p97 K524A mutant with deficient ATPase activity, the latter of which functioned as a dominant negative. Mice overexpressing wildtype p97 exhibit normal cardiac structure and function while mutant p97 overexpressing mice develop cardiomyopathy, upregulate several ERAD complex components, and have elevated levels of ubiquitinated proteins. Proteomics and immunoprecipitation assays identified overwhelming interactions between endogenous p97 and a number of interesting protein complexes that suggest unique functions for this protein in regulating protein quality control in the heart. The results and novel regulatory relationships will be presented, which suggests entirely unique pathways whereby p97 functions in the heart.

scholarly journals Proteasome Based Molecular Strategies Against Improper Cellular Proliferation

2021 ◽  
Vol 55 (S2) ◽  
pp. 120-143
Keyword(s):  
Quality Control ◽  
Tumor Progression ◽  
Cancer Progression ◽  
Cellular Proliferation ◽  
Protein Quality ◽  
Control Strategies ◽  
Protein Quality Control ◽  
Ubiquitin Proteasome System ◽  
Cellular Protein ◽  
Therapeutic Interventions

Cells contain several proteins that routinely fulfill multiple requirements for normal physiological survival. Proteostasis dysfunction is linked with different complex human disorders, like cancer, neuron degeneration, and imperfect aging. The ubiquitin proteasome system (UPS) forms the primary proteostasis mechanism taking part in cytoprotection. Cancer cells are well known to possess enhanced cytoprotective properties, and different UPS elements are implicated to be dysregulated at several stages of tumor progression. Furthermore, many studies have found tumor cells to exhibit higher levels of various UPS components, possibly contributing to their robust endurance. In this article, we have presented different cellular protein quality control strategies, essential for maintaining healthy proteome. Here, we have also discussed key contributions and functions of UPS involved in molecular pathomechanisms for establishing cancer conditions. Along with this, the emerging different therapeutic strategies against defective proteome linked with improper cellular proliferation and cancer progression are also reviewed. UPS performs critical regulatory functions in modulating the cellular apoptotic pathways. The proteasomal system involvement as probable therapeutic targets influencing cancer cell apoptosis is also discussed. Our article summarizes the recent developments in proteasome-associated pathways regulating tumor cell proteome and survival. Additionally, how the engagement and cross functions of these physiological processes can induce apoptosis and may develop regulation over tumor progression. A better understanding of multifaceted protein quality control pathways may inform therapeutic interventions based on cellular proteostasis response determined against complex diseases.

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.

Cytosolic protein quality control machinery: Interactions of Hsp70 with a network of co-chaperones and substrates

2021 ◽  
pp. 153537022199981
Author(s):  
Chamithi Karunanayake ◽  
Richard C Page
Keyword(s):  
Quality Control ◽  
Protein Quality ◽  
Protein Quality Control ◽  
Structural Features ◽  
Cellular Protein ◽  
Mechanisms Of Action ◽  
Control Mechanisms ◽  
Nucleotide Exchange ◽  
Domain Organization ◽  
Nucleotide Exchange Factors

The chaperone heat shock protein 70 (Hsp70) and its network of co-chaperones serve as a central hub of cellular protein quality control mechanisms. Domain organization in Hsp70 dictates ATPase activity, ATP dependent allosteric regulation, client/substrate binding and release, and interactions with co-chaperones. The protein quality control activities of Hsp70 are classified as foldase, holdase, and disaggregase activities. Co-chaperones directly assisting protein refolding included J domain proteins and nucleotide exchange factors. However, co-chaperones can also be grouped and explored based on which domain of Hsp70 they interact. Here we discuss how the network of cytosolic co-chaperones for Hsp70 contributes to the functions of Hsp70 while closely looking at their structural features. Comparison of domain organization and the structures of co-chaperones enables greater understanding of the interactions, mechanisms of action, and roles played in protein quality control.

scholarly journals TTC3-Mediated Protein Quality Control, A Potential Mechanism for Cognitive Impairment

2021 ◽  
Author(s):  
Xu Zhou ◽  
Xiongjin Chen ◽  
Tingting Hong ◽  
Miaoping Zhang ◽  
Yujie Cai ◽  
...  
Keyword(s):  
Quality Control ◽  
Cognitive Impairment ◽  
Protein Quality ◽  
Protein Quality Control ◽  
Ubiquitin Proteasome System ◽  
Research Progress ◽  
Repeat Domain ◽  
Ubiquitin Proteasome ◽  
Domain 3

AbstractThe tetrapeptide repeat domain 3 (TTC3) gene falls within Down's syndrome (DS) critical region. Cognitive impairment is a common phenotype of DS and Alzheimer’s disease (AD), and overexpression of TTC3 can accelerate cognitive decline, but the specific mechanism is unknown. The TTC3-mediated protein quality control (PQC) mechanism, similar to the PQC system, is divided into three parts: it acts as a cochaperone to assist proteins in folding correctly; it acts as an E3 ubiquitin ligase (E3s) involved in protein degradation processes through the ubiquitin–proteasome system (UPS); and it may also eventually cause autophagy by affecting mitochondrial function. Thus, this article reviews the research progress on the structure, function, and metabolism of TTC3, including the recent research progress on TTC3 in DS and AD; the role of TTC3 in cognitive impairment through PQC in combination with the abovementioned attributes of TTC3; and the potential targets of TTC3 in the treatment of such diseases.

Protein Quality Control in Neurodegeneration and Neuroprotection

2020 ◽  
pp. 1-24
Author(s):  
Yasmeena Akhter ◽  
Jahangir Nabi ◽  
Hinna Hamid ◽  
Nahida Tabassum ◽  
Faheem Hyder Pottoo ◽  
...  
Keyword(s):  
Quality Control ◽  
Neurodegenerative Disorders ◽  
Protein Quality ◽  
Protein Quality Control ◽  
Ubiquitin Proteasome System ◽  
Security System ◽  
Conformational Disorders ◽  
Ubiquitin Proteasome ◽  
Multi Level

Proteostasis is essential for regulating the integrity of the proteome. Disruption of proteostasis under some rigorous conditions leads to the aggregation and accumulation of misfolded toxic proteins, which plays a central role in the pathogenesis of protein conformational disorders. The protein quality control (PQC) system serves as a multi-level security system to shield cells from abnormal proteins. The intrinsic PQC systems maintaining proteostasis include the ubiquitin-proteasome system (UPS), chaperon-mediated autophagy (CMA), and autophagy-lysosome pathway (ALP) that serve to target misfolded proteins for unfolding, refolding, or degradation. Alterations of PQC systems in neurons have been implicated in the pathogenesis of various neurodegenerative disorders. This chapter provides an overview of PQC pathways to set a framework for discussion of the role of PQC in neurodegenerative disorders. Additionally, various pharmacological approaches targeting PQC are summarized.

scholarly journals Mycobacterium tuberculosis Rv0991c Is a Redox-Regulated Molecular Chaperone

mBio ◽  
2020 ◽  
Vol 11 (4) ◽  
Author(s):  
Samuel H. Becker ◽  
Kathrin Ulrich ◽  
Avantika Dhabaria ◽  
Beatrix Ueberheide ◽  
William Beavers ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Quality Control ◽  
Mycobacterium Tuberculosis ◽  
Molecular Chaperone ◽  
Protein Quality ◽  
Protein Quality Control ◽  
Cellular Protein ◽  
Content Type ◽  
Hsp70 Chaperone

ABSTRACT The bacterial pathogen Mycobacterium tuberculosis is the leading cause of death by an infectious disease among humans. Here, we describe a previously uncharacterized M. tuberculosis protein, Rv0991c, as a molecular chaperone that is activated by oxidation. Rv0991c has homologs in most bacterial lineages and appears to function analogously to the well-characterized Escherichia coli redox-regulated chaperone Hsp33, despite a dissimilar protein sequence. Rv0991c is transcriptionally coregulated with hsp60 and hsp70 chaperone genes in M. tuberculosis, suggesting that Rv0991c functions with these chaperones in maintaining protein quality control. Supporting this hypothesis, we found that, like oxidized Hsp33, oxidized Rv0991c prevents the aggregation of a model unfolded protein in vitro and promotes its refolding by the M. tuberculosis Hsp70 chaperone system. Furthermore, Rv0991c interacts with DnaK and can associate with many other M. tuberculosis proteins. We therefore propose that Rv0991c, which we named “Ruc” (redox-regulated protein with unstructured C terminus), represents a founding member of a new chaperone family that protects M. tuberculosis and other species from proteotoxicity during oxidative stress. IMPORTANCE M. tuberculosis infections are responsible for more than 1 million deaths per year. Developing effective strategies to combat this disease requires a greater understanding of M. tuberculosis biology. As in all cells, protein quality control is essential for the viability of M. tuberculosis, which likely faces proteotoxic stress within a host. Here, we identify an M. tuberculosis protein, Ruc, that gains chaperone activity upon oxidation. Ruc represents a previously unrecognized family of redox-regulated chaperones found throughout the bacterial superkingdom. Additionally, we found that oxidized Ruc promotes the protein-folding activity of the essential M. tuberculosis Hsp70 chaperone system. This work contributes to a growing body of evidence that oxidative stress provides a particular strain on cellular protein stability.

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.

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