201
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Fredrickson EK, Gardner RG. Selective destruction of abnormal proteins by ubiquitin-mediated protein quality control degradation. Semin Cell Dev Biol 2012; 23:530-7. [PMID: 22245831 DOI: 10.1016/j.semcdb.2011.12.006] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2011] [Revised: 12/19/2011] [Accepted: 12/22/2011] [Indexed: 11/30/2022]
Abstract
Misfolded proteins are continuously produced in the cell and present an escalating detriment to cellular physiology if not managed effectively. As such, all organisms have evolved mechanisms to address misfolded proteins. One primary way eukaryotic cells handle the complication of misfolded proteins is by destroying them through the ubiquitin-proteasome system. To do this, eukaryotes possess specialized ubiquitin-protein ligases that have the capacity to recognize misfolded proteins over normally folded proteins. The strategies used by these Protein Quality Control (PQC) ligases to target the wide variety of misfolded proteins in the cell will likely be different than those used by ubiquitin-protein ligases that function in regulated degradation to target normally folded proteins. In this review, we highlight what is known about how misfolded proteins are recognized by PQC ubiquitin-protein ligases.
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Affiliation(s)
- Eric K Fredrickson
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA
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202
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Hänzelmann P, Schäfer A, Völler D, Schindelin H. Structural insights into functional modes of proteins involved in ubiquitin family pathways. Methods Mol Biol 2012; 832:547-76. [PMID: 22350912 DOI: 10.1007/978-1-61779-474-2_39] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The conjugation of ubiquitin and related modifiers to selected proteins represents a general mechanism to alter the function of these protein targets, thereby increasing the complexity of the cellular proteome. Ubiquitylation is catalyzed by a hierarchical enzyme cascade consisting of ubiquitin activating, ubiquitin conjugating, and ubiquitin ligating enzymes, and their combined action results in a diverse topology of ubiquitin-linkages on the modified proteins. Counteracting this machinery are various deubiquitylating enzymes while ubiquitin recognition in all its facets is accomplished by numerous ubiquitin-binding elements. In the following chapter, we attempt to provide an overview on enzymes involved in ubiquitylation as well as the removal of ubiquitin and proteins involved in the recognition and binding of ubiquitin from a structural biologist's perspective.
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Affiliation(s)
- Petra Hänzelmann
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany
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203
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Kästle M, Grune T. Interactions of the Proteasomal System with Chaperones. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2012; 109:113-60. [DOI: 10.1016/b978-0-12-397863-9.00004-3] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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204
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Zhao H, Michaelis ML, Blagg BS. Hsp90 Modulation for the Treatment of Alzheimer’s Disease. CURRENT STATE OF ALZHEIMER'S DISEASE RESEARCH AND THERAPEUTICS 2012; 64:1-25. [DOI: 10.1016/b978-0-12-394816-8.00001-5] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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205
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Kumar P, Pradhan K, Karunya R, Ambasta RK, Querfurth HW. Cross-functional E3 ligases Parkin and C-terminus Hsp70-interacting protein in neurodegenerative disorders. J Neurochem 2011; 120:350-70. [DOI: 10.1111/j.1471-4159.2011.07588.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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206
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Ube2w and ataxin-3 coordinately regulate the ubiquitin ligase CHIP. Mol Cell 2011; 43:599-612. [PMID: 21855799 DOI: 10.1016/j.molcel.2011.05.036] [Citation(s) in RCA: 135] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2010] [Revised: 03/22/2011] [Accepted: 05/31/2011] [Indexed: 01/29/2023]
Abstract
The mechanisms by which ubiquitin ligases are regulated remain poorly understood. Here we describe a series of molecular events that coordinately regulate CHIP, a neuroprotective E3 implicated in protein quality control. Through their opposing activities, the initiator E2, Ube2w, and the specialized deubiquitinating enzyme (DUB), ataxin-3, participate in initiating, regulating, and terminating the CHIP ubiquitination cycle. Monoubiquitination of CHIP by Ube2w stabilizes the interaction between CHIP and ataxin-3, which through its DUB activity limits the length of chains attached to CHIP substrates. Upon completion of substrate ubiquitination, ataxin-3 deubiquitinates CHIP, effectively terminating the reaction. Our results suggest that functional pairing of E3s with ataxin-3 or similar DUBs represents an important point of regulation in ubiquitin-dependent protein quality control. In addition, the results shed light on disease pathogenesis in SCA3, a neurodegenerative disorder caused by polyglutamine expansion in ataxin-3.
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207
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Quality control and fate determination of Hsp90 client proteins. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2011; 1823:683-8. [PMID: 21871502 DOI: 10.1016/j.bbamcr.2011.08.006] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Revised: 08/03/2011] [Accepted: 08/04/2011] [Indexed: 12/24/2022]
Abstract
Quality control processes regulate the proteome by determining whether a protein is to be folded or degraded. Hsp90 is a hub in the network of molecular chaperones that maintain this process because it promotes both folding and degradation, in addition to regulating expression of other quality control components. The significance of Hsp90's role in quality control is enhanced by the function of its clients, which include protein kinases and transcription factors, in cellular signaling. The inhibition of Hsp90 with small molecules results in the rapid degradation of such clients via the ubiquitin/proteasome pathway, and also in the induction of the Hsp70 molecular chaperone. These two events result in markedly different outcomes depending on cell type. For tumor cells there is a profound loss of signaling in growth promoting pathways. By contrast, increased amounts of Hsp70 in neuronal cells ameliorate the toxicity that is associated with the formation of aggregates observed in neurodegenerative conditions. In this review we discuss the mechanisms underlying these differential effects of Hsp90 inhibition on the quality control of distinct client proteins. This article is part of a Special Issue entitled: Heat Shock Protein 90 (HSP90).
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208
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Abstract
The endosomal-sorting complex required for transport (ESCRT) apparatus has multiple ubiquitin (Ub)-binding domains and participates in a wide variety of cellular processes. Many of these ESCRT-dependent processes are keenly regulated by Ub, which serves as a lysosomal-sorting signal for membrane proteins targeted into multivesicular bodies (MVBs) and which may serve as a mediator of viral budding from the cell surface. Hints that both ESCRTs and Ub work together in the processes such as cytokinesis, transcription and autophagy are beginning to emerge. Here, we explore the relationship between ESCRTs and Ub in MVB sorting and viral budding.
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Affiliation(s)
- S Brookhart Shields
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, University of Iowa, Iowa City, IA 52246, USA
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209
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Allan RK, Ratajczak T. Versatile TPR domains accommodate different modes of target protein recognition and function. Cell Stress Chaperones 2011; 16:353-67. [PMID: 21153002 PMCID: PMC3118826 DOI: 10.1007/s12192-010-0248-0] [Citation(s) in RCA: 177] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2010] [Revised: 11/21/2010] [Accepted: 11/24/2010] [Indexed: 12/30/2022] Open
Abstract
The tetratricopeptide repeat (TPR) motif is one of many repeat motifs that form structural domains in proteins that can act as interaction scaffolds in the formation of multi-protein complexes involved in numerous cellular processes such as transcription, the cell cycle, protein translocation, protein degradation and host defence against invading pathogens. The crystal structures of many TPR domain-containing proteins have been determined, showing TPR motifs as two anti-parallel α-helices packed in tandem arrays to form a structure with an amphipathic groove which can bind a target peptide. This is however not the only mode of target recognition by TPR domains, with short amino acid insertions and alternative TPR motif conformations also shown to contribute to protein interactions, highlighting diversity in TPR domains and the versatility of this structure in mediating biological events.
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Affiliation(s)
- Rudi Kenneth Allan
- Centre for Medical Research, The University of Western Australia, Nedlands, WA 6009 Australia
- The Department of Endocrinology & Diabetes, Sir Charles Gairdner Hospital, Hospital Avenue, Nedlands, WA 6009 Australia
| | - Thomas Ratajczak
- Centre for Medical Research, The University of Western Australia, Nedlands, WA 6009 Australia
- The Department of Endocrinology & Diabetes, Sir Charles Gairdner Hospital, Hospital Avenue, Nedlands, WA 6009 Australia
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210
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Evolution of Vertebrate Immunity: Sequence and Functional Analysis of the SEFIR Domain Family Member Act1. J Mol Evol 2011; 72:521-30. [DOI: 10.1007/s00239-011-9450-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2011] [Accepted: 05/19/2011] [Indexed: 12/22/2022]
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211
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Fredrickson EK, Rosenbaum JC, Locke MN, Milac TI, Gardner RG. Exposed hydrophobicity is a key determinant of nuclear quality control degradation. Mol Biol Cell 2011; 22:2384-95. [PMID: 21551067 PMCID: PMC3128539 DOI: 10.1091/mbc.e11-03-0256] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Protein quality control (PQC) degradation protects the cell by preventing the toxic accumulation of misfolded proteins. In eukaryotes, PQC degradation is primarily achieved by ubiquitin ligases that attach ubiquitin to misfolded proteins for proteasome degradation. To function effectively, PQC ubiquitin ligases must distinguish misfolded proteins from their normal counterparts by recognizing an attribute of structural abnormality commonly shared among misfolded proteins. However, the nature of the structurally abnormal feature recognized by most PQC ubiquitin ligases is unknown. Here we demonstrate that the yeast nuclear PQC ubiquitin ligase San1 recognizes exposed hydrophobicity in its substrates. San1 recognition is triggered by exposure of as few as five contiguous hydrophobic residues, which defines the minimum window of hydrophobicity required for San1 targeting. We also find that the exposed hydrophobicity recognized by San1 can cause aggregation and cellular toxicity, underscoring the fundamental protective role for San1-mediated PQC degradation of misfolded nuclear proteins.
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Affiliation(s)
- Eric K Fredrickson
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA
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212
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Wang J, Zhao Q, Qi Q, Gu HY, Rong JJ, Mu R, Zou MJ, Tao L, You QD, Guo QL. Gambogic acid-induced degradation of mutant p53 is mediated by proteasome and related to CHIP. J Cell Biochem 2011; 112:509-19. [PMID: 21268072 DOI: 10.1002/jcb.22941] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
As an oncoprotein, mutant p53 is a potential tumor-specific target for cancer therapy. Most mutated forms of the protein are largely accumulated in cancer cells due to their increased stability. In the present study, we demonstrate that mutant p53 protein stability is regulated by gambogic acid (GA). Following GA exposure, protein levels of mutant p53 decreased while the mRNA levels were not affected in MDA-MB-435 cells, which indicate that GA down-regulates mutant p53 at post-transcription level. Co-treatment with GA and cycloheximide, a protein synthesis inhibitor, induced a decrease of half-life of mutant p53 protein. These findings indicated that the reduction of mutant p53 by GA was due to the destabilization and degradation of the protein. Furthermore, inhibition of proteasome activity by MG132 blocked GA-induced down-regulation of mutant p53, causing mutant p53 accumulation in detergent-insoluble cellular fractions. Further studies revealed that mutant p53 was ubiquitinated and it was chaperones related ubiquitin ligase carboxy terminus of Hsp70-interacting protein (CHIP) rather than MDM2 involved in the degradation of mutant p53. In addition, GA prevented Hsp90/mutant p53 complex formation and enhanced interaction of mutant p53 with Hsp70. Depletion of CHIP stabilized mutant p53 in GA treated cells. In conclusion, mutant p53 may be down-regulated by GA through chaperones-assisted ubiquitin/proteasome degradation pathway in cancer cells.
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Affiliation(s)
- Jia Wang
- Jiangsu Key Laboratory of Carcinogenesis and Intervention, China Pharmaceutical University, Jiangsu, China
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213
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Suaud L, Miller K, Alvey L, Yan W, Robay A, Kebler C, Kreindler JL, Guttentag S, Hubbard MJ, Rubenstein RC. ERp29 regulates DeltaF508 and wild-type cystic fibrosis transmembrane conductance regulator (CFTR) trafficking to the plasma membrane in cystic fibrosis (CF) and non-CF epithelial cells. J Biol Chem 2011; 286:21239-53. [PMID: 21525008 DOI: 10.1074/jbc.m111.240267] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Sodium 4-phenylbutyrate (4PBA) improves the intracellular trafficking of ΔF508-CFTR in cystic fibrosis (CF) epithelial cells. The underlying mechanism is uncertain, but 4PBA modulates the expression of some cytosolic molecular chaperones. To identify other 4PBA-regulated proteins that might regulate ΔF508-CFTR trafficking, we performed a differential display RT-PCR screen on IB3-1 CF bronchiolar epithelial cells exposed to 4PBA. One transcript up-regulated by 4PBA encoded ERp29, a luminal resident of the endoplasmic reticulum (ER) thought to be a novel molecular chaperone. We tested the hypothesis that ERp29 is a 4PBA-regulated ER chaperone that influences ΔF508-CFTR trafficking. ERp29 mRNA and protein expression was significantly increased (∼1.5-fold) in 4PBA-treated IB3-1 cells. In Xenopus oocytes, ERp29 overexpression increased the functional expression of both wild-type and ΔF508-CFTR over 3-fold and increased wild-type cystic fibrosis transmembrane conductance regulator (CFTR) plasma membrane expression. In CFBE41o- WT-CFTR cells, expression of and short circuit currents mediated by CFTR decreased upon depletion of ERp29 as did maturation of newly synthesized CFTR. In IB3-1 cells, ΔF508-CFTR co-immunoprecipitated with endogenous ERp29, and overexpression of ERp29 led to increased ΔF508-CFTR expression at the plasma membrane. These data suggest that ERp29 is a 4PBA-regulated ER chaperone that regulates WT-CFTR biogenesis and can promote ΔF508-CFTR trafficking in CF epithelial cells.
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Affiliation(s)
- Laurence Suaud
- Division of Pulmonary Medicine and Cystic Fibrosis Center, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania 19104, USA
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214
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Soss SE, Yue Y, Dhe-Paganon S, Chazin WJ. E2 conjugating enzyme selectivity and requirements for function of the E3 ubiquitin ligase CHIP. J Biol Chem 2011; 286:21277-86. [PMID: 21518764 DOI: 10.1074/jbc.m111.224006] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The transfer of ubiquitin (Ub) to a substrate protein requires a cascade of E1 activating, E2 conjugating, and E3 ligating enzymes. E3 Ub ligases containing U-box and RING domains bind both E2∼Ub conjugates and substrates to facilitate transfer of the Ub molecule. Although the overall mode of action of E3 ligases is well established, many of the mechanistic details that determine the outcome of ubiquitination are poorly understood. CHIP (carboxyl terminus of Hsc70-interacting protein) is a U-box E3 ligase that serves as a co-chaperone to heat shock proteins and is critical for the regulation of unfolded proteins in the cytosol. We have performed a systematic analysis of the interactions of CHIP with E2 conjugating enzymes and found that only a subset bind and function. Moreover, some E2 enzymes function in pairs to create products that neither create individually. Characterization of the products of these reactions showed that different E2 enzymes produce different ubiquitination products, i.e. that E2 determines the outcome of Ub transfer. Site-directed mutagenesis on the E2 enzymes Ube2D1 and Ube2L3 (UbcH5a and UbcH7) established that an SPA motif in loop 7 of E2 is required for binding to CHIP but is not sufficient for activation of the E2∼Ub conjugate and consequent ubiquitination activity. These data support the proposal that the E2 SPA motif provides specificity for binding to CHIP, whereas activation of the E2∼Ub conjugate is derived from other molecular determinants.
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Affiliation(s)
- Sarah E Soss
- Department of Biochemistry, Vanderbilt University, Nashville, Tennessee 37232, USA
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215
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Rankin CA, Roy A, Zhang Y, Richter M. Parkin, A Top Level Manager in the Cell's Sanitation Department. Open Biochem J 2011; 5:9-26. [PMID: 21633666 PMCID: PMC3104551 DOI: 10.2174/1874091x01105010009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2010] [Revised: 01/25/2011] [Accepted: 01/31/2011] [Indexed: 01/31/2023] Open
Abstract
Parkin belongs to a class of multiple RING domain proteins designated as RBR (RING, in between RING, RING) proteins. In this review we examine what is known regarding the structure/function relationship of the Parkin protein. Parkin contains three RING domains plus a ubiquitin-like domain and an in-between-RING (IBR) domain. RING domains are rich in cysteine amino acids that act as ligands to bind zinc ions. RING domains may interact with DNA or with other proteins and perform a wide range of functions. Some function as E3 ubiquitin ligases, participating in attachment of ubiquitin chains to signal proteasome degradation; however, ubiquitin may be attached for purposes other than proteasome degradation. It was determined that the C-terminal most RING, RING2, is essential for Parkin to function as an E3 ubiquitin ligase and a number of substrates have been identified. However, Parkin also participates in a number of other fiunctions, such as DNA repair, microtubule stabilization, and formation of aggresomes. Some functions, such as participation in a multi-protein complex implicated in NMDA activity at the post synaptic density, do not require ubiquitination of substrate molecules. Recent observations of RING proteins suggest their function may be regulated by zinc ion binding. We have modeled the three RING domains of Parkin and have identified a new set of RING2 ligands. This set allows for binding of two rather than just one zinc ion, opening the possibility that the number of zinc ions bound acts as a molecular switch to modulate Parkin function.
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Affiliation(s)
- Carolyn A Rankin
- Molecular Biosciences Department, University of Kansas, Lawrence KS 66045, USA
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216
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Wolfe KJ, Cyr DM. Amyloid in neurodegenerative diseases: friend or foe? Semin Cell Dev Biol 2011; 22:476-81. [PMID: 21458579 DOI: 10.1016/j.semcdb.2011.03.011] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Revised: 03/21/2011] [Accepted: 03/24/2011] [Indexed: 01/06/2023]
Abstract
Accumulation of amyloid-like aggregates is a hallmark of numerous neurodegenerative disorders such as Alzheimer's and polyglutamine disease. Yet, whether the amyloid inclusions found in these diseases are toxic or cytoprotective remains unclear. Various studies suggest that the toxic culprit in the amyloid folding pathway is actually a soluble oligomeric species which might interfere with normal cellular function by a multifactorial mechanism including aberrant protein-protein interactions. Molecular chaperones suppress toxicity of amyloidogenic proteins by inhibiting aggregation of non-native disease substrates and targeting them for refolding or degradation. Paradoxically, recent studies also suggest a protective action of chaperones in their promotion of the assembly of large, tightly packed, benign aggregates that sequester toxic protein species.
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Affiliation(s)
- Katie J Wolfe
- Department of Cell and Developmental Biology, School of Medicine, University of North Carolina at Chapel Hill, 107 Mason Farm Road, Chapel Hill, NC 27514, United States
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217
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Li W, Yang Q, Mao Z. Chaperone-mediated autophagy: machinery, regulation and biological consequences. Cell Mol Life Sci 2011; 68:749-63. [PMID: 20976518 PMCID: PMC11114861 DOI: 10.1007/s00018-010-0565-6] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2010] [Revised: 10/07/2010] [Accepted: 10/08/2010] [Indexed: 10/18/2022]
Abstract
Degradation of dysfunctional intracellular components in the lysosome system can occur through three different pathways, i.e., macroautophagy, microautophagy and chaperone-mediated autophagy (CMA). In this review, we focus on CMA, a type of autophagy distinct from the other two autophagic pathways owing to its selectivity, saturability and competitivity by which a subset of long-lived cytosolic soluble proteins are directly delivered into the lysosomal lumen via specific receptors. CMA participates in quality control to maintain normal cell functions by clearing "old" proteins and provides energy to cells under nutritional stress. Deregulation of CMA has recently been shown to underlie some diseases, especially neurodegenerative disorders for which the decline with age in the activity of CMA may become a major aggravating factor. Therefore, targeting aberrant alteration in CMA under pathological conditions could serve as a potential therapeutic strategy for treating related diseases.
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Affiliation(s)
- Wenming Li
- Departments of Pharmacology and Neurology, Emory University School of Medicine, Atlanta, GA 30322 USA
| | - Qian Yang
- Departments of Pharmacology and Neurology, Emory University School of Medicine, Atlanta, GA 30322 USA
| | - Zixu Mao
- Departments of Pharmacology and Neurology, Emory University School of Medicine, Atlanta, GA 30322 USA
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218
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Wang Q, Song F, Zhang C, Zhao X, Zhu Z, Yu S, Xie K. Carboxyl-terminus of Hsc70 interacting protein mediates 2,5-hexanedione-induced neurofilament medium chain degradation. Biochem Pharmacol 2011; 81:793-9. [DOI: 10.1016/j.bcp.2010.12.021] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2010] [Revised: 12/20/2010] [Accepted: 12/21/2010] [Indexed: 10/18/2022]
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219
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Kalia SK, Kalia LV, McLean PJ. Molecular chaperones as rational drug targets for Parkinson's disease therapeutics. CNS & NEUROLOGICAL DISORDERS-DRUG TARGETS 2011; 9:741-53. [PMID: 20942788 DOI: 10.2174/187152710793237386] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2010] [Accepted: 03/30/2010] [Indexed: 12/19/2022]
Abstract
Parkinson's disease is a neurodegenerative movement disorder that is caused, in part, by the loss of dopaminergic neurons within the substantia nigra pars compacta of the basal ganglia. The presence of intracellular protein aggregates, known as Lewy bodies and Lewy neurites, within the surviving nigral neurons is the defining neuropathological feature of the disease. Accordingly, the identification of specific genes mutated in families with Parkinson's disease and of genetic susceptibility variants for idiopathic Parkinson's disease has implicated abnormalities in proteostasis, or the handling and elimination of misfolded proteins, in the pathogenesis of this neurodegenerative disorder. Protein folding and the refolding of misfolded proteins are regulated by a network of interactive molecules, known as the chaperone system, which is composed of molecular chaperones and co-chaperones. The chaperone system is intimately associated with the ubiquitin-proteasome system and the autophagy-lysosomal pathway which are responsible for elimination of misfolded proteins and protein quality control. In addition to their role in proteostasis, some chaperone molecules are involved in the regulation of cell death pathways. Here we review the role of the molecular chaperones Hsp70 and Hsp90, and the cochaperones Hsp40, BAG family members such as BAG5, CHIP and Hip in modulating neuronal death with a focus on dopaminergic neurodegeneration in Parkinson's disease. We also review current progress in preclinical studies aimed at targetting the chaperone system to prevent neurodegeneration. Finally, we discuss potential future chaperone-based therapeutics for the symptomatic treatment and possible disease modification of Parkinson's disease.
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Affiliation(s)
- S K Kalia
- Department of Neurology, Massachusetts General Hospital, Mass General Institute for Neurodegenerative Disease, 114 16th Street, Charlestown, MA 02129, USA
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220
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Kalia LV, Kalia SK, Chau H, Lozano AM, Hyman BT, McLean PJ. Ubiquitinylation of α-synuclein by carboxyl terminus Hsp70-interacting protein (CHIP) is regulated by Bcl-2-associated athanogene 5 (BAG5). PLoS One 2011; 6:e14695. [PMID: 21358815 PMCID: PMC3040167 DOI: 10.1371/journal.pone.0014695] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2010] [Accepted: 01/25/2011] [Indexed: 11/19/2022] Open
Abstract
Parkinson's disease (PD) is a common neurodegenerative condition in which abnormalities in protein homeostasis, or proteostasis, may lead to accumulation of the protein α-synuclein (α-syn). Mutations within or multiplications of the gene encoding α-syn are known to cause genetic forms of PD and polymorphisms in the gene are recently established risk factors for idiopathic PD. α-syn is a major component of Lewy bodies, the intracellular proteinaceous inclusions which are pathological hallmarks of most forms of PD. Recent evidence demonstrates that α-syn can self associate into soluble oligomeric species and implicates these α-syn oligomers in cell death. We have previously shown that carboxyl terminus of Hsp70-interacting protein (CHIP), a co-chaperone molecule with E3 ubiquitin ligase activity, may reduce the levels of toxic α-syn oligomers. Here we demonstrate that α-syn is ubiquitinylated by CHIP both in vitro and in cells. We find that the products from ubiquitinylation by CHIP include both monoubiquitinylated and polyubiquitinylated forms of α-syn. We also demonstrate that CHIP and α-syn exist within a protein complex with the co-chaperone bcl-2-associated athanogene 5 (BAG5) in brain. The interaction of CHIP with BAG5 is mediated by Hsp70 which binds to the tetratricopeptide repeat domain of CHIP and the BAG domains of BAG5. The Hsp70-mediated association of BAG5 with CHIP results in inhibition of CHIP E3 ubiquitin ligase activity and subsequently reduces α-syn ubiquitinylation. Furthermore, we use a luciferase-based protein-fragment complementation assay of α-syn oligomerization to investigate regulation of α-syn oligomers by CHIP in living cells. We demonstrate that BAG5 mitigates the ability of CHIP to reduce α-syn oligomerization and that non-ubiquitinylated α-syn has an increased propensity for oligomerization. Thus, our results identify CHIP as an E3 ubiquitin ligase of α-syn and suggest a novel function for BAG5 as a modulator of CHIP E3 ubiquitin ligase activity with implications for CHIP-mediated regulation of α-syn oligomerization.
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Affiliation(s)
- Lorraine V Kalia
- Department of Neurology, MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts, United States of America.
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221
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Min T, Bodas M, Mazur S, Vij N. Critical role of proteostasis-imbalance in pathogenesis of COPD and severe emphysema. J Mol Med (Berl) 2011; 89:577-93. [PMID: 21318260 DOI: 10.1007/s00109-011-0732-8] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2010] [Revised: 01/18/2011] [Accepted: 01/21/2011] [Indexed: 12/18/2022]
Abstract
The environmental, genetic, and/or age-related changes in proteostasis induce inflammation, oxidative stress, and apoptosis. We quantified the correlation of protein expression of critical proteostasis mediators to severity of chronic lung disease using lung tissue samples from control and chronic obstructive pulmonary disease (COPD) subjects (GOLD stage 0-IV) and cigarette smoke (CS)-induced murine model. The human bronchial epithelial cells, HEK-293, and Beas2B cells were used for in vitro experiments to verify the mechanisms. Our data verifies the correlation of higher expression of valosin-containing protein (VCP) retrograde translocation complex (VCP-Rma1-gp78) with severity of emphysema in COPD lung tissues and over-expression of inflammatory, ER stress and apoptotic mediators like NFκB, GADD-153/CHOP, and p-eIF2α. Moreover, subjects with severe emphysema had a higher accumulation of ubiquitinated proteins and deubiquitinating enzyme, UCHL-1, indicating towards the aggregation of misfolded or damaged proteins. The modulation of both protein degradation and synthesis rates by CS-extract substantiates the pathogenetic role of proteostasis-imbalance in emphysema and COPD. We identified that VCP also mediates proteasomal degradation of HDAC2 and Nrf2, as a potential mechanism for increased oxidative stress and corticosteroid resistance in COPD subjects with emphysema. Next, we confirmed that higher VCP expression associates with increased inflammation and apoptosis using in vitro and murine models. Our data clearly shows aberrant proteostasis in COPD subjects with severe emphysema. In addition, we evaluate therapeutic efficacy of salubrinal (ER stress inhibitor) to correct the proteostasis-imbalance based on its ability to control VCP expression and ubiquitin accumulation. Overall, our data demonstrate for the first time the critical role of proteostasis-imbalance in pathogenesis of severe emphysema.
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Affiliation(s)
- Taehong Min
- Division of Pediatric Respiratory Sciences, Department of Pediatrics, Johns Hopkins University, Baltimore, MD 21287, USA
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222
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Oh KH, Yang SW, Park JM, Seol JH, Iemura S, Natsume T, Murata S, Tanaka K, Jeon YJ, Chung CH. Control of AIF-mediated cell death by antagonistic functions of CHIP ubiquitin E3 ligase and USP2 deubiquitinating enzyme. Cell Death Differ 2011; 18:1326-36. [PMID: 21293491 DOI: 10.1038/cdd.2011.3] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Apoptosis inducing factor (AIF) is a mitochondrial oxidoreductase that scavenges reactive oxygen species under normal conditions. Under certain stresses, such as exposure to N-methyl-N'-nitro-N'-nitrosoguanidine (MNNG), AIF is truncated and released from the mitochondria and translocated into the nucleus, where the truncated AIF (tAIF) induces caspase-independent cell death. However, it is unknown how cells decide to kill themselves or operate ways to survive when they encounter stresses that induce the release of tAIF. Here, we demonstrated that USP2 and CHIP contribute to the control of tAIF stability. USP2 deubiquitinated and stabilized tAIF, thus promoting AIF-mediated cell death. In contrast, CHIP ubiquitinated and destabilized tAIF, thus preventing the cell death. Consistently, CHIP-deficient cells showed an increased sensitivity to MNNG. On the other hand, knockdown of USP2 attenuated MNNG-induced cell death. Moreover, exposure to MNNG caused a dramatic decrease in CHIP level, but not that of USP2, concurrent with cell shrinkage and chromatin condensation. These findings indicate that CHIP and USP2 show antagonistic functions in the control of AIF-mediated cell death, and implicate the role of the enzymes as a switch for cells to live or die under stresses that cause tAIF release.
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Affiliation(s)
- K H Oh
- School of Biological Sciences, Seoul National University, Seoul, Korea
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223
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Nishiya T, Matsumoto K, Maekawa S, Kajita E, Horinouchi T, Fujimuro M, Ogasawara K, Uehara T, Miwa S. Regulation of inducible nitric-oxide synthase by the SPRY domain- and SOCS box-containing proteins. J Biol Chem 2011; 286:9009-19. [PMID: 21199876 DOI: 10.1074/jbc.m110.190678] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Inducible nitric-oxide synthase (iNOS, NOS2) plays a prominent role in macrophage bactericidal and tumoricidal activities. A relatively large amount of NO produced via iNOS, however, also targets the macrophage itself for apoptotic cell death. To uncover the intrinsic mechanisms of iNOS regulation, we have characterized the SPRY domain- and SOCS box-containing protein 1 (SPSB1), SPSB2, and SPSB4 that interact with the N-terminal region of iNOS in a D-I-N-N-N sequence-dependent manner. Fluorescence microscopy revealed that these SPSB proteins can induce the subcellular redistribution of iNOS from dense regions to diffused expression in a SOCS box-dependent manner. In immunoprecipitation studies, both Elongin C and Cullin-5, components of the multi-subunit E3 ubiquitin ligase, were found to bind to iNOS via SPSB1, SPSB2, or SPSB4. Consistently, iNOS was polyubiquitinated and degraded in a proteasome-dependent manner when SPSB1, SPSB2, or SPSB4 was expressed. SPSB1 and SPSB4 had a greater effect on iNOS regulation than SPSB2. The iNOS N-terminal fragment (residues 1-124 of human iNOS) could disrupt iNOS-SPSB interactions and inhibit iNOS degradation. In lipopolysaccharide-treated macrophages, this fragment attenuated iNOS ubiquitination and substantially prolonged iNOS lifetime, resulting in a corresponding increase in NO production and enhanced NO-dependent cell death. These results not only demonstrate the mechanism of SPSB-mediated iNOS degradation and the relative contributions of different SPSB proteins to iNOS regulation, but also show that iNOS levels are sophisticatedly regulated by SPSB proteins in activated macrophages to prevent overproduction of NO that could trigger detrimental effects, such as cytotoxicity.
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Affiliation(s)
- Tadashi Nishiya
- Department of Cellular Pharmacology, Hokkaido University Graduate School of Medicine, Sapporo 060-8638, Japan.
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224
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Abstract
CHIP, the carboxyl-terminus of Hsp70 interacting protein, is both an E3 ubiquitin ligase and an Hsp70 co-chaperone and is implicated in the degradation of cytosolic quality control and numerous disease substrates. CHIP has been shown to monitor the folding status of the CFTR protein, and we have successfully reconstituted this activity using a recombinant CFTR fragment consisting of the cytosolic NBD1 and R domains. We have found that efficient ubiquitination of substrates requires chaperone activity to either deliver the substrate to CHIP or to maintain the substrate in a ubiquitination-competent conformation. This chaperone activity can be provided by the Hsp70/Hsp40 molecular chaperone system as seen in the NBD1-R ubiquitination assay. Alternatively, heat treatment of CHIP can activate its own innate substrate-binding activity and allow for efficient ubiquitination of model substrates, such as denatured luciferase. Here, we describe methods for purifying the recombinant proteins necessary for in vitro reconstitution of CHIP ubiquitin ligase activity, as well as two methods used to monitor CHIP ligase activity. One method allows for the measurement of the Hsp70- and Hsp40-dependent CHIP activity while the other measures the Hsp40- and Hsp70-independent activity of heat-activated CHIP.
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225
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Sisoula C, Trachana V, Patterson C, Gonos ES. CHIP-dependent p53 regulation occurs specifically during cellular senescence. Free Radic Biol Med 2011; 50:157-65. [PMID: 20974249 DOI: 10.1016/j.freeradbiomed.2010.10.701] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2010] [Revised: 09/10/2010] [Accepted: 10/18/2010] [Indexed: 01/24/2023]
Abstract
p53 regulates several biological processes, including senescence. Its protein stability is regulated by ubiquitination and proteasomal degradation, mainly mediated by Mdm2. However, other E3 ligases have been identified, such as the chaperone-associated ligase CHIP, although their precise function regarding p53 degradation remains elusive. Interestingly, CHIP deficiency has been recently shown to result in accelerated aging in mice, although the molecular basis of this phenotype was not completely understood. In this study, we explore the role of CHIP in regulating p53 in senescence. We demonstrate that in senescent human fibroblasts, CHIP is up-regulated concomitant with a significant down-regulation of p53. Moreover, CHIP partially translocates to the nucleus and acquires higher ubiquitination levels in senescent cells. Notably, CHIP overexpression in young cells, to levels similar to those recorded during senescence, leads to p53 degradation to below its basal levels. In addition, whereas CHIP silencing has no effect on p53 stability in young cells, a considerable p53 accumulation occurs in their senescent counterparts. Finally, we have observed an attenuation of the CHIP-associated molecular folding-refolding machinery during senescence, and supportively, inhibition of Hsp90 activity leads to rapid p53 degradation only in senescent cells. Taking these results together, we conclude that CHIP-dependent p53 regulation occurs specifically during senescence.
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Affiliation(s)
- Christina Sisoula
- National Hellenic Research Foundation, Institute of Biological Research and Biotechnology, Athens 11635, Greece
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226
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Woo CH, Le NT, Shishido T, Chang E, Lee H, Heo KS, Mickelsen DM, Lu Y, McClain C, Spangenberg T, Yan C, Molina CA, Yang J, Patterson C, Abe JI. Novel role of C terminus of Hsc70‐interacting protein (CHIP) ubiquitin ligase on inhibiting cardiac apoptosis and dysfunction
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regulating ERK5‐mediated degradation of inducible cAMP early repressor. FASEB J 2010. [DOI: 10.1096/fj.10.162636] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Chang-Hoon Woo
- Aab Cardiovascular Research InstituteUniversity of Rochester Rochester New York USA
| | - Nhat-Tu Le
- Aab Cardiovascular Research InstituteUniversity of Rochester Rochester New York USA
| | - Tetsuro Shishido
- Department of CardiologyPulmonology, and Nephrology, Yamagata University School of Medicine Yamagata Japan
| | - Eugene Chang
- Aab Cardiovascular Research InstituteUniversity of Rochester Rochester New York USA
| | - Hakjoo Lee
- Aab Cardiovascular Research InstituteUniversity of Rochester Rochester New York USA
| | - Kyung-Sun Heo
- Aab Cardiovascular Research InstituteUniversity of Rochester Rochester New York USA
| | - Deanne M. Mickelsen
- Aab Cardiovascular Research InstituteUniversity of Rochester Rochester New York USA
| | - Yan Lu
- Aab Cardiovascular Research InstituteUniversity of Rochester Rochester New York USA
| | - Carolyn McClain
- Department of Biology and Molecular BiologyMontclair State University Montclair New Jersey USA
| | - Thomas Spangenberg
- Department of AnesthesiologyUniversity of Wisconsin Madison Wisconsin USA
| | - Chen Yan
- “Carolina Cardiovascular Biology CenterUniversity of North Carolina Chapel Hill North Carolina USA
| | - Carlos A. Molina
- Aab Cardiovascular Research InstituteUniversity of Rochester Rochester New York USA
| | - Jay Yang
- Aab Cardiovascular Research InstituteUniversity of Rochester Rochester New York USA
| | - Cam Patterson
- Aab Cardiovascular Research InstituteUniversity of Rochester Rochester New York USA
| | - Jun-ichi Abe
- Aab Cardiovascular Research InstituteUniversity of Rochester Rochester New York USA
- Department of CardiologyPulmonology, and Nephrology, Yamagata University School of Medicine Yamagata Japan
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227
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Willis MS, Patterson C. Hold me tight: Role of the heat shock protein family of chaperones in cardiac disease. Circulation 2010; 122:1740-51. [PMID: 20975010 DOI: 10.1161/circulationaha.110.942250] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Monte S Willis
- McAllister Heart Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7126, USA
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228
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Patani N, Jiang W, Newbold R, Mokbel K. Prognostic implications of carboxyl-terminus of Hsc70 interacting protein and lysyl-oxidase expression in human breast cancer. J Carcinog 2010; 9:9. [PMID: 21139993 PMCID: PMC2997236 DOI: 10.4103/1477-3163.72505] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2010] [Accepted: 06/11/2010] [Indexed: 11/30/2022] Open
Abstract
Background: Ubiquitin modification of proteins influences cellular processes relevant to carcinogenesis. CHIP (carboxyl-terminus of Hsc70-interacting protein) is a chaperone-dependent E3 ubiquitin ligase, regulating the stability of heat shock protein 90 (HSP90) interacting proteins. CHIP is implicated in the modulation of estrogen receptor (ESR1) and Her-2/neu (ERBB2) stability. LOX (lysyl-oxidase) serves intracellular roles and catalyses the cross-linking of extracellular matrix (ECM) collagens and elastin. LOX expression is altered in human malignancies and their peri-tumoral stroma. However, paradoxical roles are reported. In this study, the level of mRNA expression of CHIP and LOX were assessed in normal and malignant breast tissue and correlated with clinico-pathological parameters. Materials and Methods: Breast cancer (BC) tissues (n = 127) and normal tissues (n = 33) underwent RNA extraction and reverse transcription; transcript levels were determined using real-time quantitative PCR and normalized against CK-19. Transcript levels were analyzed against TNM stage, nodal involvement, tumor grade and clinical outcome over a ten-year follow-up period. Results: CHIP expression decreased with increasing Nottingham Prognostic Index (NPI): NPI-1 vs. NPI-3 (12.2 vs. 0.2, P = 0.0264), NPI-2 vs. NPI-3 (3 vs. 0.2, P = 0.0275). CHIP expression decreased with increasing TNM stage: TNM-1 vs. TNM-2 (12 vs. 0, P = 0.0639), TNM-1 vs. TNM-2-4 (12 vs. 0, P = 0.0434). Lower transcript levels were associated with increasing tumor grade: grade 1 vs. grade 3 (17.7 vs. 0.3, P = 0.0266), grade 2 vs. grade 3 (5 vs. 0.3, P = 0.0454). The overall survival (OS) for tumors classified as ‘low-level expression’, was poorer than those with ‘high-level expression’ (118.1 vs. 152.3 months, P = 0.039). LOX expression decreased with increasing NPI: NPI-1 vs. NPI-2 (3 vs. 0, P = 0.0301) and TNM stage: TNM-1 = 3854639, TNM-2 = 908900, TNM-3 = 329, TNM-4 = 1.232 (P = NS). Conclusion: CHIP expression is associated with favorable prognostic parameters, including tumor grade, TNM stage and NPI. CHIP expression predicts OS. LOX expression is associated with improved NPI. In addition to their prognostic utility, mechanistic insights into tumor suppressor function may offer potential therapeutic strategies.
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Affiliation(s)
- Neill Patani
- Department of Breast Surgery, The London Breast Institute, The Princess Grace Hospital, London
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229
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Abstract
Background The patterns of emergence and diversification of the families of ubiquitin ligases provide insights about the evolution of the eukaryotic ubiquitination system. U-box ubiquitin ligases (UULs) are proteins characterized by containing a peculiar protein domain known as U box. In this study, the origin of the animal UUL genes is described. Results Phylogenetic and structural data indicate that six of the seven main UUL-encoding genes found in humans (UBE4A, UBE4B, UIP5, PRP19, CHIP and CYC4) were already present in the ancestor of all current metazoans and the seventh (WDSUB1) is found in placozoans, cnidarians and bilaterians. The fact that only 4 - 5 genes orthologous to the human ones are present in the choanoflagellate Monosiga brevicollis suggests that several animal-specific cooptions of the U box to generate new genes occurred. Significantly, Monosiga contains five additional UUL genes that are not present in animals. One of them is also present in distantly-related protozoans. Along animal evolution, losses of UUL-encoding genes are rare, except in nematodes, which lack three of them. These general patterns are highly congruent with those found for other two families (RBR, HECT) of ubiquitin ligases. Conclusions Finding that the patterns of emergence, diversification and loss of three unrelated families of ubiquitin ligases (RBR, HECT and U-box) are parallel indicates that there are underlying, linage-specific evolutionary forces shaping the complexity of the animal ubiquitin system.
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230
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Lee JH, Khadka P, Baek SH, Chung IK. CHIP promotes human telomerase reverse transcriptase degradation and negatively regulates telomerase activity. J Biol Chem 2010; 285:42033-45. [PMID: 20959453 DOI: 10.1074/jbc.m110.149831] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The maintenance of eukaryotic telomeres requires telomerase, which is minimally composed of a telomerase reverse transcriptase (TERT) and an associated RNA component. Telomerase activity is tightly regulated by expression of human (h) TERT at both the transcriptional and post-translational levels. The Hsp90 and p23 molecular chaperones have been shown to associate with hTERT for the assembly of active telomerase. Here, we show that CHIP (C terminus of Hsc70-interacting protein) physically associates with hTERT in the cytoplasm and regulates the cellular abundance of hTERT through a ubiquitin-mediated degradation. Overexpression of CHIP prevents nuclear translocation of hTERT and promotes hTERT degradation in the cytoplasm, thereby inhibiting telomerase activity. In contrast, knockdown of endogenous CHIP results in the stabilization of cytoplasmic hTERT. However, it does not affect the level of nuclear hTERT and has no effect on telomerase activity and telomere length. We further show that the binding of CHIP and Hsp70 to hTERT inhibits nuclear translocation of hTERT by dissociating p23. However, Hsp90 binding to hTERT was not affected by CHIP overexpression. These results suggest that CHIP can remodel the hTERT-chaperone complexes. Finally, the amount of hTERT associated with CHIP peaks in G(2)/M phases but decreases during S phase, suggesting a cell cycle-dependent regulation of hTERT. Our data suggest that CHIP represents a new pathway for modulating telomerase activity in cancer.
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Affiliation(s)
- Ji Hoon Lee
- Departments of Biology and Biomedical Science, World Class University Program of Graduate School, Yonsei University, Seoul 20-749, Korea
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231
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Narayan V, Pion E, Landré V, Müller P, Ball KL. Docking-dependent ubiquitination of the interferon regulatory factor-1 tumor suppressor protein by the ubiquitin ligase CHIP. J Biol Chem 2010; 286:607-19. [PMID: 20947504 DOI: 10.1074/jbc.m110.153122] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Characteristically for a regulatory protein, the IRF-1 tumor suppressor turns over rapidly with a half-life of between 20-40 min. This allows IRF-1 to reach new steady state protein levels swiftly in response to changing environmental conditions. Whereas CHIP (C terminus of Hsc70-interacting protein), appears to chaperone IRF-1 in unstressed cells, formation of a stable IRF-1·CHIP complex is seen under specific stress conditions. Complex formation, in heat- or heavy metal-treated cells, is accompanied by a decrease in IRF-1 steady state levels and an increase in IRF-1 ubiquitination. CHIP binds directly to an intrinsically disordered domain in the central region of IRF-1 (residues 106-140), and this site is sufficient to form a stable complex with CHIP in cells and to compete in trans with full-length IRF-1, leading to a reduction in its ubiquitination. The study reveals a complex relationship between CHIP and IRF-1 and highlights the role that direct binding or "docking" of CHIP to its substrate(s) can play in its mechanism of action as an E3 ligase.
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Affiliation(s)
- Vikram Narayan
- CRUK Interferon and Cell Signalling Group, Cell Signalling Unit, Institute of Genetics and Molecular Medicine, Crewe Road South, University of Edinburgh, Edinburgh EH4 2XR, United Kingdom
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232
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Karkoulis PK, Stravopodis DJ, Margaritis LH, Voutsinas GE. 17-Allylamino-17-demethoxygeldanamycin induces downregulation of critical Hsp90 protein clients and results in cell cycle arrest and apoptosis of human urinary bladder cancer cells. BMC Cancer 2010; 10:481. [PMID: 20828379 PMCID: PMC2944179 DOI: 10.1186/1471-2407-10-481] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2010] [Accepted: 09/09/2010] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND 17-Allylamino-17-demethoxygeldanamycin (17-AAG), a benzoquinone ansamycin antibiotic, specifically targets heat shock protein 90 (Hsp90) and interferes with its function as a molecular chaperone that maintains the structural and functional integrity of various protein clients involved in cellular signaling. In this study, we have investigated the effect of 17-AAG on the regulation of Hsp90-dependent signaling pathways directly implicated in cell cycle progression, survival and motility of human urinary bladder cancer cell lines. METHODS We have used MTT-based assays, FACS analysis, Western blotting, semi-quantitative RT-PCR, immunocytochemistry and scratch-wound assay in RT4, RT112 and T24 human urinary bladder cancer cell lines. RESULTS We have demonstrated that, upon 17-AAG treatment, bladder cancer cells are arrested in the G1 phase of the cell cycle and eventually undergo apoptotic cell death in a dose-dependent manner. Furthermore, 17-AAG administration was shown to induce a pronounced downregulation of multiple Hsp90 protein clients and other downstream effectors, such as IGF-IR, Akt, IKK-α, IKK-β, FOXO1, ERK1/2 and c-Met, resulting in sequestration-mediated inactivation of NF-κB, reduced cell proliferation and decline of cell motility. CONCLUSIONS In total, we have clearly evinced a dose-dependent and cell type-specific effect of 17-AAG on cell cycle progression, survival and motility of human bladder cancer cells, due to downregulation of multiple Hsp90 clients and subsequent disruption of signaling integrity.
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Affiliation(s)
- Panagiotis K Karkoulis
- Laboratory of Environmental Mutagenesis and Carcinogenesis, Institute of Biology, National Center for Scientific Research (NCSR) Demokritos, 15310 Athens, Greece
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233
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Kim SM, Acharya P, Engel JC, Correia MA. Liver cytochrome P450 3A ubiquitination in vivo by gp78/autocrine motility factor receptor and C terminus of Hsp70-interacting protein (CHIP) E3 ubiquitin ligases: physiological and pharmacological relevance. J Biol Chem 2010; 285:35866-77. [PMID: 20819951 DOI: 10.1074/jbc.m110.167189] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
CYP3A4 is a dominant human liver cytochrome P450 enzyme engaged in the metabolism and disposition of >50% of clinically relevant drugs and held responsible for many adverse drug-drug interactions. CYP3A4 and its mammalian liver CYP3A orthologs are endoplasmic reticulum (ER)-anchored monotopic proteins that undergo ubiquitin (Ub)-dependent proteasomal degradation (UPD) in an ER-associated degradation (ERAD) process. These integral ER proteins are ubiquitinated in vivo, and in vitro studies have identified the ER-integral gp78 and the cytosolic co-chaperone, CHIP (C terminus of Hsp70-interacting protein), as the relevant E3 Ub-ligases, along with their cognate E2 Ub-conjugating enzymes UBC7 and UbcH5a, respectively. Using lentiviral shRNA templates targeted against each of these Ub-ligases, we now document that both E3s are indeed physiologically involved in CYP3A ERAD/UPD in cultured rat hepatocytes. Accordingly, specific RNAi resulted in ≈80% knockdown of each hepatic Ub-ligase, with a corresponding ≈2.5-fold CYP3A stabilization. Surprisingly, however, such stabilization resulted in increased levels of functionally active CYP3A, thereby challenging the previous notion that E3 recognition and subsequent ERAD of CYP3A proteins required ab initio their structural and/or functional inactivation. Furthermore, coexpression in HepG2 cells of both CYP3A4 and gp78, but not its functionally inactive RING-finger mutant, resulted in enhanced CYP3A4 loss greater than that in corresponding cells expressing only CYP3A4. Stabilization of a functionally active CYP3A after RNAi knockdown of either of the E3s, coupled with the increased CYP3A4 loss on gp78 or CHIP coexpression, suggests that ERAD-associated E3 Ub-ligases can influence clinically relevant drug metabolism by effectively regulating the physiological CYP3A content and consequently its function.
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Affiliation(s)
- Sung-Mi Kim
- Department of Cellular & Molecular Pharmacology, Bioengineering & Therapeutic Sciences and the Liver Center, University of California, San Francisco, California 94158-2517, USA
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234
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Anderson LG, Meeker RB, Poulton WE, Huang DY. Brain distribution of carboxy terminus of Hsc70-interacting protein (CHIP) and its nuclear translocation in cultured cortical neurons following heat stress or oxygen-glucose deprivation. Cell Stress Chaperones 2010; 15:487-95. [PMID: 19953350 PMCID: PMC3006630 DOI: 10.1007/s12192-009-0162-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2008] [Accepted: 11/18/2009] [Indexed: 12/25/2022] Open
Abstract
Carboxy terminus of Hsc70-interacting protein (CHIP) is thought to be a cytoprotective protein with protein quality control roles in neurodegenerative diseases and myocardial ischemia. This study describes the localization of CHIP expression in normal rodent brain and the early CHIP response in primary cultures of cortical neurons following ischemic stress models: heat stress (HS) and oxygen-glucose deprivation (OGD). CHIP was highly expressed throughout the brain, predominantly in neurons. The staining pattern was primarily cytoplasmic, although small amounts were seen in the nucleus. More intense nuclear staining was observed in primary cultured neurons which increased with stress. Nuclear accumulation of CHIP occurred within 5-10 min of HS and decreased to baseline levels or lower by 30-60 min. Decrease in nuclear CHIP at 30-60 min of HS was associated with a sharp increase in delayed cell death. While no changes in cytoplasmic CHIP were observed immediately following OGD, nuclear levels of CHIP increased slightly in response to OGD durations of 30 to 240 min. OGD-induced increases in nuclear CHIP decreased slowly during post-ischemic recovery. Nuclear CHIP decreased earlier in recovery following 120 min of OGD (4 h) than 30 min of OGD (12 h). Significant cell death first appeared between 12 and 24 h after OGD, again suggesting that delayed cell death follows closely behind the disappearance of nuclear CHIP. The ability of CHIP to translocate to and accumulate in the nucleus may be a limiting variable that determines how effectively cells respond to external stressors to facilitate cell survival. Using primary neuronal cell cultures, we were able to demonstrate rapid translocation of CHIP to the nucleus within minutes of heat stress and oxygen-glucose deprivation. An inverse relationship between nuclear CHIP and delayed cell death at 24 h suggests that the decrease in nuclear CHIP following extreme stress is linked to delayed cell death. Our findings of acute changes in subcellular localization of CHIP in response to cellular stress suggest that cellular changes that occur shortly after exposure to stress ultimately impact on the capacity and capability of a cell to recover and survive.
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Affiliation(s)
- Lauren G. Anderson
- Curriculum in Neurobiology, University of North Carolina at Chapel Hill, Chapel Hill, NC USA
| | - Rick B. Meeker
- Curriculum in Neurobiology, University of North Carolina at Chapel Hill, Chapel Hill, NC USA
- Department of Neurology, University of North Carolina at Chapel Hill, CB #7025, Physicians Office Building, Chapel Hill, NC 27599-7025 USA
| | - Winona E. Poulton
- Department of Neurology, University of North Carolina at Chapel Hill, CB #7025, Physicians Office Building, Chapel Hill, NC 27599-7025 USA
| | - David Y. Huang
- Curriculum in Neurobiology, University of North Carolina at Chapel Hill, Chapel Hill, NC USA
- Department of Neurology, University of North Carolina at Chapel Hill, CB #7025, Physicians Office Building, Chapel Hill, NC 27599-7025 USA
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235
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Clapp KM, Peng HM, Morishima Y, Lau M, Walker VJ, Pratt WB, Osawa Y. C331A mutant of neuronal nitric-oxide synthase is labilized for Hsp70/CHIP (C terminus of HSC70-interacting protein)-dependent ubiquitination. J Biol Chem 2010; 285:33642-51. [PMID: 20729196 DOI: 10.1074/jbc.m110.159178] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
It is established that suicide inactivation of neuronal nitric-oxide synthase (nNOS) by drugs and other xenobiotics leads to ubiquitination and proteasomal degradation of the enzyme. The exact mechanism is not known, although it is widely thought that the covalent alteration of the active site during inactivation triggers the degradation. A mechanism that involves recognition of the altered nNOS by Hsp70 and its cochaperone CHIP, an E3-ubiquitin ligase, has been proposed. To further address how alterations of the active site trigger ubiquitination of nNOS, we examined a C331A nNOS mutant, which was reported to have impaired ability to bind L-arginine and tetrahydrobiopterin. We show here that C331A nNOS is highly susceptible to ubiquitination by a purified system containing ubiquitinating enzymes and chaperones, by the endogenous ubiquitinating system in reticulocyte lysate fraction II, and by intact HEK293 cells. The involvement of the altered heme cleft in regulating ubiquitination is confirmed by the finding that the slowly reversible inhibitor of nNOS, N(G)-nitro-L-arginine, but not its inactive D-isomer, protects the C331A nNOS from ubiquitination in all these experimental systems. We also show that both Hsp70 and CHIP play a major role in the ubiquitination of C331A nNOS, although Hsp90 protects from ubiquitination. Thus, these studies further strengthen the link between the mobility of the substrate-binding cleft and chaperone-dependent ubiquitination of nNOS. These results support a general model of chaperone-mediated protein quality control and lead to a novel mechanism for substrate stabilization based on nNOS interaction with the chaperone machinery.
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Affiliation(s)
- Kelly M Clapp
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA
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236
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Woo CH, Le NT, Shishido T, Chang E, Lee H, Heo KS, Mickelsen DM, Lu Y, McClain C, Spangenberg T, Yan C, Molina CA, Yang J, Patterson C, Abe JI. Novel role of C terminus of Hsc70-interacting protein (CHIP) ubiquitin ligase on inhibiting cardiac apoptosis and dysfunction via regulating ERK5-mediated degradation of inducible cAMP early repressor. FASEB J 2010; 24:4917-28. [PMID: 20724525 DOI: 10.1096/fj.10-162636] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Growing evidence indicates a critical role of ubiquitin-proteosome system in apoptosis regulation. A cardioprotective effect of ubiquitin (Ub) ligase of the C terminus of Hsc70-interacting protein (CHIP) on myocytes has been reported. In the current study, we found that the cardioprotective effect of insulin growth factor-1 (IGF-1) was mediated by ERK5-CHIP signal module via inducible cAMP early repressor (ICER) destabilization. In vitro runoff assay and Ub assay showed ICER as a substrate of CHIP Ub ligase. Both disruption of ERK5-CHIP binding with inhibitory helical linker domain fragment (aa 101-200) of CHIP and the depletion of ERK5 by siRNA inhibited CHIP Ub ligase activity, which suggests an obligatory role of ERK5 on CHIP activation. Depletion of CHIP, using siRNA, inhibited IGF-1-mediated reduction of isoproterenol-mediated ICER induction and apoptosis. In diabetic mice subjected to myocardial infarction, the CHIP Ub ligase activity was decreased, with an increase in ICER expression. These changes were attenuated significantly in a cardiac-specific constitutively active form of MEK5α transgenic mice (CA-MEK5α-Tg) previously shown to have greater functional recovery. Furthermore, pressure overload-mediated ICER induction was enhanced in heterozygous CHIP(+/-) mice. We identified ICER as a novel CHIP substrate and that the ERK5-CHIP complex plays an obligatory role in inhibition of ICER expression, cardiomyocyte apoptosis, and cardiac dysfunction.
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Affiliation(s)
- Chang-Hoon Woo
- Aab Cardiovascular Research Institute, University of Rochester, Rochester, New York 14642, USA
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237
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Minami R, Hayakawa A, Kagawa H, Yanagi Y, Yokosawa H, Kawahara H. BAG-6 is essential for selective elimination of defective proteasomal substrates. ACTA ACUST UNITED AC 2010; 190:637-50. [PMID: 20713601 PMCID: PMC2928017 DOI: 10.1083/jcb.200908092] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
BAG-6/Scythe/BAT3 is a ubiquitin-like protein that was originally reported to be the product of a novel gene located within the human major histocompatibility complex, although the mechanisms of its function remain largely obscure. Here, we demonstrate the involvement of BAG-6 in the degradation of a CL1 model defective protein substrate in mammalian cells. We show that BAG-6 is essential for not only model substrate degradation but also the ubiquitin-mediated metabolism of newly synthesized defective polypeptides. Furthermore, our in vivo and in vitro analysis shows that BAG-6 interacts physically with puromycin-labeled nascent chain polypeptides and regulates their proteasome-mediated degradation. Finally, we show that knockdown of BAG-6 results in the suppressed presentation of MHC class I on the cell surface, a procedure known to be affected by the efficiency of metabolism of defective ribosomal products. Therefore, we propose that BAG-6 is necessary for ubiquitin-mediated degradation of newly synthesized defective polypeptides.
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Affiliation(s)
- Ryosuke Minami
- Department of Biological Sciences, Tokyo Metropolitan University, Tokyo, Japan
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238
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Schülke JP, Wochnik GM, Lang-Rollin I, Gassen NC, Knapp RT, Berning B, Yassouridis A, Rein T. Differential impact of tetratricopeptide repeat proteins on the steroid hormone receptors. PLoS One 2010; 5:e11717. [PMID: 20661446 PMCID: PMC2908686 DOI: 10.1371/journal.pone.0011717] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2009] [Accepted: 06/24/2010] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Tetratricopeptide repeat (TPR) motif containing co-chaperones of the chaperone Hsp90 are considered control modules that govern activity and specificity of this central folding platform. Steroid receptors are paradigm clients of Hsp90. The influence of some TPR proteins on selected receptors has been described, but a comprehensive analysis of the effects of TPR proteins on all steroid receptors has not been accomplished yet. METHODOLOGY AND PRINCIPAL FINDINGS We compared the influence of the TPR proteins FK506 binding proteins 51 and 52, protein phosphatase-5, C-terminus of Hsp70 interacting protein, cyclophillin 40, hepatitis-virus-B X-associated protein-2, and tetratricopeptide repeat protein-2 on all six steroid hormone receptors in a homogeneous mammalian cell system. To be able to assess each cofactor's effect on the transcriptional activity of on each steroid receptor we employed transient transfection in a reporter gene assay. In addition, we evaluated the interactions of the TPR proteins with the receptors and components of the Hsp90 chaperone heterocomplex by coimmunoprecipitation. In the functional assays, corticosteroid and progesterone receptors displayed the most sensitive and distinct reaction to the TPR proteins. Androgen receptor's activity was moderately impaired by most cofactors, whereas the Estrogen receptors' activity was impaired by most cofactors only to a minor degree. Second, interaction studies revealed that the strongly receptor-interacting co-chaperones were all among the inhibitory proteins. Intriguingly, the TPR-proteins also differentially co-precipitated the heterochaperone complex components Hsp90, Hsp70, and p23, pointing to differences in their modes of action. CONCLUSION AND SIGNIFICANCE The results of this comprehensive study provide important insight into chaperoning of diverse client proteins via the combinatorial action of (co)-chaperones. The differential effects of the TPR proteins on steroid receptors bear on all physiological processes related to steroid hormone activity.
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MESH Headings
- Animals
- Cell Line
- Cell Line, Tumor
- Peptidyl-Prolyl Isomerase F
- Cyclophilins/genetics
- Cyclophilins/metabolism
- HSP40 Heat-Shock Proteins/genetics
- HSP40 Heat-Shock Proteins/metabolism
- Heat-Shock Proteins
- Humans
- Immunoblotting
- Immunoprecipitation
- Intracellular Signaling Peptides and Proteins/genetics
- Intracellular Signaling Peptides and Proteins/metabolism
- Mice
- Molecular Chaperones
- Nuclear Proteins/genetics
- Nuclear Proteins/metabolism
- Phosphoprotein Phosphatases/genetics
- Phosphoprotein Phosphatases/metabolism
- Receptors, Androgen/genetics
- Receptors, Androgen/metabolism
- Receptors, Estrogen/genetics
- Receptors, Estrogen/metabolism
- Receptors, Glucocorticoid/genetics
- Receptors, Glucocorticoid/metabolism
- Receptors, Mineralocorticoid/genetics
- Receptors, Mineralocorticoid/metabolism
- Receptors, Progesterone/genetics
- Receptors, Progesterone/metabolism
- Receptors, Steroid/genetics
- Receptors, Steroid/metabolism
- Tacrolimus Binding Proteins/genetics
- Tacrolimus Binding Proteins/metabolism
- Ubiquitin-Protein Ligases/genetics
- Ubiquitin-Protein Ligases/metabolism
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Affiliation(s)
- Jan-Philip Schülke
- Chaperone Research Group, Max Planck Institute of Psychiatry, Munich, Germany
| | | | | | | | | | - Barbara Berning
- Chaperone Research Group, Max Planck Institute of Psychiatry, Munich, Germany
| | | | - Theo Rein
- Chaperone Research Group, Max Planck Institute of Psychiatry, Munich, Germany
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239
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Zucchelli S, Codrich M, Marcuzzi F, Pinto M, Vilotti S, Biagioli M, Ferrer I, Gustincich S. TRAF6 promotes atypical ubiquitination of mutant DJ-1 and alpha-synuclein and is localized to Lewy bodies in sporadic Parkinson's disease brains. Hum Mol Genet 2010; 19:3759-70. [DOI: 10.1093/hmg/ddq290] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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240
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Heat shock protein 70 together with its co-chaperone CHIP inhibits TNF-alpha induced apoptosis by promoting proteasomal degradation of apoptosis signal-regulating kinase1. Apoptosis 2010; 15:822-33. [PMID: 20349136 DOI: 10.1007/s10495-010-0495-7] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Inducible heat shock protein70 (HSP70) is one of the most important HSPs for maintenance of cell integrity during normal cellular growth as well as pathophysiological conditions. Apoptosis signal-regulating kinase (ASK) 1, a mammalian MAPKKK, activates the JNK and p38 pathways. Here we report a novel function of HSP70 in regulating TNF-alpha-induced cell apoptosis. Our study demonstrated that HSP70 physically interacted with ASK1 and promoted the ubiquitin-dependent proteasomal degradation of ASK1. CHIP (carboxyl terminus of the HSC70-interacting protein) which acted as a co-chaperone of HSP70 cooperated with HSP70 in regulating ASK1. We also found that TNF-alpha stimulated HSP70/CHIP/ASK1 association and through cooperating with CHIP, HSP70 inhibits TNF-alpha-induced cell apoptosis both in over-expression and RNAi conditions. Structural analysis indicated that C-terminal domain of HSP70 was necessary for ASK1 degradation, and N- terminal domain of ASK1 was essential for its binding to HSP70. All these findings indicated that HSP70 and CHIP association is important for HSP70 in interacting with ASK1. Through forming the complex of HSP70/CHIP/ASK1, HSP70 promotes ASK1 proteasomal degradation and prevents TNF-alpha-induced cell apoptosis.
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241
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Maruyama T, Kadowaki H, Okamoto N, Nagai A, Naguro I, Matsuzawa A, Shibuya H, Tanaka K, Murata S, Takeda K, Nishitoh H, Ichijo H. CHIP-dependent termination of MEKK2 regulates temporal ERK activation required for proper hyperosmotic response. EMBO J 2010; 29:2501-14. [PMID: 20588253 DOI: 10.1038/emboj.2010.141] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2010] [Accepted: 05/31/2010] [Indexed: 11/09/2022] Open
Abstract
The extracellular signal-regulated kinase (ERK) pathway is an important signalling pathway that regulates a large number of cellular processes, including proliferation, differentiation and gene expression. Hyperosmotic stress activates the ERK pathway, whereas little is known about the regulatory mechanisms and physiological functions of ERK activation in hyperosmotic response. Here, we show that MAPK/ERK kinase kinase 2 (MEKK2), a member of the MAPKKK family, mediated the specific and transient activation of ERK, which was required for the induction of aquaporin 1 (AQP1) and AQP5 gene expression in response to hyperosmotic stress. Moreover, we identified the E3 ubiquitin ligase carboxyl terminus of Hsc70-interacting protein (CHIP) as a binding partner of MEKK2. Depletion of CHIP by small-interference RNA or gene targeting attenuated the degradation of MEKK2 and prolonged the ERK activity. Interestingly, hyperosmolality-induced gene expression of AQP1 and AQP5 was suppressed by CHIP depletion and was reversed by inhibition of the prolonged phase of ERK activity. These findings show that transient activation of the ERK pathway, which depends not only on MEKK2 activation, but also on CHIP-dependent MEKK2 degradation, is crucial for proper gene expression in hyperosmotic stress response.
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Affiliation(s)
- Takeshi Maruyama
- Department of Medical Pharmaceutics, Laboratory of Cell Signaling, Japan Science and Technology Corporation, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
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242
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Pratt WB, Morishima Y, Peng HM, Osawa Y. Proposal for a role of the Hsp90/Hsp70-based chaperone machinery in making triage decisions when proteins undergo oxidative and toxic damage. Exp Biol Med (Maywood) 2010; 235:278-89. [PMID: 20404045 DOI: 10.1258/ebm.2009.009250] [Citation(s) in RCA: 152] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The Hsp90/Hsp70-based chaperone machinery plays a well-established role in signaling protein function, trafficking and turnover. A number of recent observations also support the notion that Hsp90 and Hsp70 play key roles in the triage of damaged and aberrant proteins for degradation via the ubiquitin-proteasome pathway. In the mid-1990s, it was discovered that Hsp70 is required for ubiquitin-dependent degradation of short-lived and abnormal proteins, and it became clear that inhibition of Hsp90 uniformly leads to the proteasomal degradation of Hsp90 client proteins. Subsequently, CHIP and parkin were shown to be Hsp70-binding ubiquitin E3 ligases that direct ubiquitin-charged E2 enzymes to the Hsp70-bound client protein. Stabilization by Hsp90 reflects the interaction of the chaperone with the ligand binding cleft of the client protein. These hydrophobic clefts must be open to allow passage of ligands to binding sites in the protein interior, and they are inherent sites of conformational instability. Hsp90 stabilizes the open state of the cleft and prevents Hsp70-dependent ubiquitination. In the model we propose here, progressive oxidative events result in cleft opening as the initial step in protein unfolding, and as long as Hsp90 can interact to stabilize the cleft, it will buffer the effect of oxidative damage. When cleft opening is such that Hsp90 can no longer interact, Hsp70-dependent ubiquitination occurs. We summarize evidence that Hsp90 interacts very dynamically with a variety of proteins that are not classic Hsp90 clients, and we show that this dynamic cycling of Hsp90 with nitric oxide synthase protects against CHIP-mediated ubiquitination. Scientific interest to date has focused on stringent regulation of the classic client proteins, which have metastable clefts and are inherently short lived. But, the recognition that Hsp90 cycles dynamically with longer lived proteins with more stable clefts may permit extension of the triage model to the quality control of damaged proteins in general.
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Affiliation(s)
- William B Pratt
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, 48109, USA
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243
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Dolan PJ, Johnson GVW. A caspase cleaved form of tau is preferentially degraded through the autophagy pathway. J Biol Chem 2010; 285:21978-87. [PMID: 20466727 DOI: 10.1074/jbc.m110.110940] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The microtubule-associated protein tau plays a central role in the pathogenesis of Alzheimer disease (AD) and abnormally accumulates as neurofibrillary tangles; therefore, the pathways by which tau is degraded have been examined extensively. In AD brain tau is abnormally truncated at Asp(421) (tauDeltaC), which increases its fibrillogenic properties and results in compromised neuronal function. Given the fact that the accumulation of tauDeltaC is a pathogenic process in AD, in this study we examined whether full-length tau and tauDeltaC are degraded through similar or different mechanisms. To this end a tetracycline-inducible model was used to show that tauDeltaC was degraded significantly faster than full-length tau (FL-tau). Pharmacological inhibition of the proteasome or autophagy pathways demonstrated that although FL-tau is degraded by the proteasome, tauDeltaC is cleared predominantly by macroautophagy. We also found that tauDeltaC binds C terminus of Hsp70-interacting protein more efficiently than tau. This interaction leads to an increased ubiquitylation of tauDeltaC in a reconstituted in vitro assay, but surprisingly, tau (full-length or truncated) was not ubiquitylated in situ. The finding that tauDeltaC and FL-tau are differentially processed by these degradation systems provides important insights for the development of therapeutic strategies, which are focused on modulating degradation systems to preferentially clear pathological forms of the proteins.
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Affiliation(s)
- Philip J Dolan
- Department of Cell Biology, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
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244
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Wang AM, Morishima Y, Clapp KM, Peng HM, Pratt WB, Gestwicki JE, Osawa Y, Lieberman AP. Inhibition of hsp70 by methylene blue affects signaling protein function and ubiquitination and modulates polyglutamine protein degradation. J Biol Chem 2010; 285:15714-23. [PMID: 20348093 DOI: 10.1074/jbc.m109.098806] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The Hsp90/Hsp70-based chaperone machinery regulates the activity and degradation of many signaling proteins. Cycling with Hsp90 stabilizes client proteins, whereas Hsp70 interacts with chaperone-dependent E3 ubiquitin ligases to promote protein degradation. To probe these actions, small molecule inhibitors of Hsp70 would be extremely useful; however, few have been identified. Here we test the effects of methylene blue, a recently described inhibitor of Hsp70 ATPase activity, in three well established systems of increasing complexity. First, we demonstrate that methylene blue inhibits the ability of the purified Hsp90/Hsp70-based chaperone machinery to enable ligand binding by the glucocorticoid receptor and show that this effect is due to specific inhibition of Hsp70. Next, we establish that ubiquitination of neuronal nitric-oxide synthase by the native ubiquitinating system of reticulocyte lysate is dependent upon both Hsp70 and the E3 ubiquitin ligase CHIP and is blocked by methylene blue. Finally, we demonstrate that methylene blue impairs degradation of the polyglutamine expanded androgen receptor, an Hsp90 client mutated in spinal and bulbar muscular atrophy. In contrast, degradation of an amino-terminal fragment of the receptor, which lacks the ligand binding domain and, therefore, is not a client of the Hsp90/Hsp70-based chaperone machinery, is enhanced through homeostatic induction of autophagy that occurs when Hsp70-dependent proteasomal degradation is inhibited by methylene blue. Our data demonstrate the utility of methylene blue in defining Hsp70-dependent functions and reveal divergent effects on polyglutamine protein degradation depending on whether the substrate is an Hsp90 client.
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Affiliation(s)
- Adrienne M Wang
- Department of Pathology, The University of Michigan Medical School, Ann Arbor, Michigan 48109, USA
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245
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Choi JS, Lee DH. CHIP promotes the degradation of mutant SOD1 by reducing its interaction with VCP and S6/S6′ subunits of 26S proteasome. Anim Cells Syst (Seoul) 2010. [DOI: 10.1080/19768351003765145] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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246
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Ran F, Gadura N, Michels CA. Hsp90 cochaperone Aha1 is a negative regulator of the Saccharomyces MAL activator and acts early in the chaperone activation pathway. J Biol Chem 2010; 285:13850-62. [PMID: 20177068 DOI: 10.1074/jbc.m109.040600] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Aha1 is a ubiquitous cochaperone of the Hsp90/Hsp70 chaperone machine. It binds the middle domain of Hsp90 and stimulates ATPase activity, suggesting a function late in the chaperone pathway. Saccharomyces Mal63 MAL activator is a DNA-binding transcription factor and Hsp90 client protein. This study utilizes several MAL activator mutants to investigate Aha1 function in vivo. Deletion of AHA1 enhances induced Mal63-dependent maltase activity levels 2-fold, whereas overproduction of Aha1 represses expression. Maltase expression in strains carrying constitutive and super-inducible mutant activators with alterations near the C terminus (particularly residues 433-463) is unaffected by either aha1Delta or Aha1 overproduction. However, another constitutive activator with alterations outside of this C-terminal region is sensitive to Aha1 regulation. Previously, we showed that in the absence of inducer, Mal63 forms a stable intermediate complex with Hsp70, Hsp90, and Sti1, whereas noninducible mutant activators bind only with Hsp70 in an apparent early complex. Here, we find that triple Myc-tagged Aha1/Myc3 copurifies with all noninducible Mal63 mutant activators tested. Aha1/Myc3 association with inducible Mal63 is observed only in a sti1Delta strain, in which Hsp90 binding and intermediate complex formation are defective. Constitutive and super-inducible mutant activators with C-terminal alterations do not bind Aha1 even in a sti1Delta strain. Mal63 binding to Hsp90 and Hsp70 is enhanced 3-fold by loss of Aha1. These results suggest an interaction between Aha1 and residues near the C terminus of Mal63 thereby regulating Hsp90 association. A novel mechanism for the negative regulation of the MAL activator by Aha1 cochaperone is proposed.
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Affiliation(s)
- Fulai Ran
- Biology Department, Queens College-City University of New York, Flushing, New York 11367, USA
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247
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Luo W, Zhong J, Chang R, Hu H, Pandey A, Semenza GL. Hsp70 and CHIP selectively mediate ubiquitination and degradation of hypoxia-inducible factor (HIF)-1alpha but Not HIF-2alpha. J Biol Chem 2010; 285:3651-3663. [PMID: 19940151 PMCID: PMC2823506 DOI: 10.1074/jbc.m109.068577] [Citation(s) in RCA: 176] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2009] [Revised: 10/30/2009] [Indexed: 01/16/2023] Open
Abstract
Hypoxia-inducible factors (HIFs) are transcription factors that mediate adaptive responses to reduced oxygen availability. HIF-alpha subunits are stabilized under conditions of acute hypoxia. However, prolonged hypoxia leads to decay of HIF-1alpha but not HIF-2alpha protein levels by unknown mechanisms. Here, we identify Hsp70 and CHIP (carboxyl terminus of Hsc70-interacting protein) as HIF-1alpha-interacting proteins. Hsp70, through recruiting the ubiquitin ligase CHIP, promotes the ubiquitination and proteasomal degradation of HIF-1alpha but not HIF-2alpha, thereby inhibiting HIF-1-dependent gene expression. Disruption of Hsp70-CHIP interaction blocks HIF-1alpha degradation mediated by Hsp70 and CHIP. Inhibition of Hsp70 or CHIP synthesis by RNA interference increases protein levels of HIF-1alpha but not HIF-2alpha and attenuates the decay of HIF-1alpha levels during prolonged hypoxia. Thus, Hsp70- and CHIP-dependent ubiquitination represents a molecular mechanism by which prolonged hypoxia selectively reduces the levels of HIF-1alpha but not HIF-2alpha protein.
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Affiliation(s)
- Weibo Luo
- From the Vascular Program, Institute for Cell Engineering, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205; McKusick-Nathans Institute of Genetic Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Jun Zhong
- Departments of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Ryan Chang
- From the Vascular Program, Institute for Cell Engineering, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205; McKusick-Nathans Institute of Genetic Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Hongxia Hu
- From the Vascular Program, Institute for Cell Engineering, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205; McKusick-Nathans Institute of Genetic Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Akhilesh Pandey
- McKusick-Nathans Institute of Genetic Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205; Departments of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205; Departments of Oncology, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205; Departments of Pathology, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Gregg L Semenza
- From the Vascular Program, Institute for Cell Engineering, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205; McKusick-Nathans Institute of Genetic Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205; Departments of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205; Departments of Oncology, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205; Departments of Pediatrics, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205; Departments of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205; Departments of Radiation Oncology, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
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248
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Cytoplasmic protein quality control degradation mediated by parallel actions of the E3 ubiquitin ligases Ubr1 and San1. Proc Natl Acad Sci U S A 2009; 107:1106-11. [PMID: 20080635 DOI: 10.1073/pnas.0910591107] [Citation(s) in RCA: 225] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Eukaryotic cells maintain proteostasis by quality control (QC) degradation. These pathways can specifically target a wide variety of distinct misfolded proteins, and so are important for management of cellular stress. Although a number of conserved QC pathways have been described in yeast, the E3 ligases responsible for cytoplasmic QC are unknown. We now show that Ubr1 and San1 mediate chaperone-dependent ubiquitination of numerous misfolded cytoplasmic proteins. This action of Ubr1 is distinct from its role in the "N-end rule." In this capacity, Ubr1 functions to protect cells from proteotoxic stresses. Our phenotypic and biochemical studies of Ubr1 and San1 indicate that two strategies are employed for cytoplasmic QC: chaperone-assisted ubiquitination by Ubr1 and chaperone-dependent delivery to nuclear San1. The broad conservation of Ubr ligases and the relevant chaperones indicates that these mechanisms will be important in understanding both basic and biomedical aspects of cellular proteostasis.
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249
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Thompson LM, Aiken CT, Kaltenbach LS, Agrawal N, Illes K, Khoshnan A, Martinez-Vincente M, Arrasate M, O'Rourke JG, Khashwji H, Lukacsovich T, Zhu YZ, Lau AL, Massey A, Hayden MR, Zeitlin SO, Finkbeiner S, Green KN, LaFerla FM, Bates G, Huang L, Patterson PH, Lo DC, Cuervo AM, Marsh JL, Steffan JS. IKK phosphorylates Huntingtin and targets it for degradation by the proteasome and lysosome. ACTA ACUST UNITED AC 2009; 187:1083-99. [PMID: 20026656 PMCID: PMC2806289 DOI: 10.1083/jcb.200909067] [Citation(s) in RCA: 275] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Expansion of the polyglutamine repeat within the protein Huntingtin (Htt) causes Huntington's disease, a neurodegenerative disease associated with aging and the accumulation of mutant Htt in diseased neurons. Understanding the mechanisms that influence Htt cellular degradation may target treatments designed to activate mutant Htt clearance pathways. We find that Htt is phosphorylated by the inflammatory kinase IKK, enhancing its normal clearance by the proteasome and lysosome. Phosphorylation of Htt regulates additional post-translational modifications, including Htt ubiquitination, SUMOylation, and acetylation, and increases Htt nuclear localization, cleavage, and clearance mediated by lysosomal-associated membrane protein 2A and Hsc70. We propose that IKK activates mutant Htt clearance until an age-related loss of proteasome/lysosome function promotes accumulation of toxic post-translationally modified mutant Htt. Thus, IKK activation may modulate mutant Htt neurotoxicity depending on the cell's ability to degrade the modified species.
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250
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Lee S, Lee DW, Lee Y, Mayer U, Stierhof YD, Lee S, Jürgens G, Hwang I. Heat shock protein cognate 70-4 and an E3 ubiquitin ligase, CHIP, mediate plastid-destined precursor degradation through the ubiquitin-26S proteasome system in Arabidopsis. THE PLANT CELL 2009; 21:3984-4001. [PMID: 20028838 PMCID: PMC2814507 DOI: 10.1105/tpc.109.071548] [Citation(s) in RCA: 158] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Plastid-targeted proteins pass through the cytosol as unfolded precursors. If proteins accumulate in the cytosol, they can form nonspecific aggregates that cause severe cellular damage. Here, we demonstrate that high levels of plastid precursors are degraded through the ubiquitin-proteasome system (UPS) in Arabidopsis thaliana cells. The cytosolic heat shock protein cognate 70-4 (Hsc70-4) and E3 ligase carboxy terminus of Hsc70-interacting protein (CHIP) were highly induced in plastid protein import2 plants, which had a T-DNA insertion at Toc159 and showed an albino phenotype and a severe defect in protein import into chloroplasts. Hsc70-4 and CHIP together mediated plastid precursor degradation when import-defective chloroplast-targeted reporter proteins were transiently expressed in protoplasts. Hsc70-4 recognized specific sequence motifs in transit peptides and thereby led to precursor degradation through the UPS. CHIP, which interacted with Hsc70-4, functioned as an E3 ligase in the Hsc70-4-mediated protein degradation. The physiological role of Hsc70-4 was confirmed by analyzing Hsc70-4 RNA interference plants in an hsc70-1 mutant background. Plants with lower Hsc70 levels exhibited abnormal embryogenesis, resulting in defective seedlings that displayed high levels of reactive oxygen species and monoubiquitinated Lhcb4 precursors. We propose that Hsc70-4 and CHIP mediate plastid-destined precursor degradation to prevent cytosolic precursor accumulation and thereby play a critical role in embryogenesis.
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Affiliation(s)
- Sookjin Lee
- Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang, 790-784, Korea
| | - Dong Wook Lee
- Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang, 790-784, Korea
| | - Yongjik Lee
- Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang, 790-784, Korea
- Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, Pohang, 790-784, Korea
| | - Ulrike Mayer
- Center for Plant Molecular Biology, University of Tübingen, D-72076 Tübingen, Germany
| | - York-Dieter Stierhof
- Center for Plant Molecular Biology, University of Tübingen, D-72076 Tübingen, Germany
| | - Sumin Lee
- Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang, 790-784, Korea
| | - Gerd Jürgens
- Center for Plant Molecular Biology, University of Tübingen, D-72076 Tübingen, Germany
| | - Inhwan Hwang
- Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang, 790-784, Korea
- Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, Pohang, 790-784, Korea
- Address correspondence to
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