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Mazaira GI, Erlejman AG, Zgajnar NR, Piwien-Pilipuk G, Galigniana MD. The transportosome system as a model for the retrotransport of soluble proteins. Mol Cell Endocrinol 2023; 577:112047. [PMID: 37604241 DOI: 10.1016/j.mce.2023.112047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2023] [Revised: 08/08/2023] [Accepted: 08/17/2023] [Indexed: 08/23/2023]
Abstract
The classic model of action of the glucocorticoid receptor (GR) sustains that its associated heat-shock protein of 90-kDa (HSP90) favours the cytoplasmic retention of the unliganded GR, whereas the binding of steroid triggers the dissociation of HSP90 allowing the passive nuclear accumulation of GR. In recent years, it was described a molecular machinery called transportosome that is responsible for the active retrograde transport of GR. The transportosome heterocomplex includes a dimer of HSP90, the stabilizer co-chaperone p23, and FKBP52 (FK506-binding protein of 52-kDa), an immunophilin that binds dynein/dynactin motor proteins. The model shows that upon steroid binding, FKBP52 is recruited to the GR allowing its active retrograde transport on cytoskeletal tracks. Then, the entire GR heterocomplex translocates through the nuclear pore complex. The HSP90-based heterocomplex is released in the nucleoplasm followed by receptor dimerization. Subsequent findings demonstrated that the transportosome is also responsible for the retrotransport of other soluble proteins. Importantly, the disruption of this molecular oligomer leads to several diseases. In this article, we discuss the relevance of this transport machinery in health and disease.
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Affiliation(s)
- Gisela I Mazaira
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales de la Universidad de Buenos Aires, Buenos Aires, 1428, Argentina; Instituto de Química Biológica de la, Facultad de Ciencias Exactas y Naturales, CONICET, Buenos Aires, 1428, Argentina
| | - Alejandra G Erlejman
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales de la Universidad de Buenos Aires, Buenos Aires, 1428, Argentina; Instituto de Química Biológica de la, Facultad de Ciencias Exactas y Naturales, CONICET, Buenos Aires, 1428, Argentina
| | - Nadia R Zgajnar
- Instituto de Biología y Medicina Experimental, CONICET, Buenos Aires, 1428, Argentina
| | | | - Mario D Galigniana
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales de la Universidad de Buenos Aires, Buenos Aires, 1428, Argentina; Instituto de Biología y Medicina Experimental, CONICET, Buenos Aires, 1428, Argentina.
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Borin C, Pieters T, Serafin V, Ntziachristos P. Emerging Epigenetic and Posttranslational Mechanisms Controlling Resistance to Glucocorticoids in Acute Lymphoblastic Leukemia. Hemasphere 2023; 7:e916. [PMID: 37359189 PMCID: PMC10289758 DOI: 10.1097/hs9.0000000000000916] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Accepted: 05/16/2023] [Indexed: 06/28/2023] Open
Abstract
Glucocorticoids are extensively used for the treatment of acute lymphoblastic leukemia as they pressure cancer cells to undergo apoptosis. Nevertheless, glucocorticoid partners, modifications, and mechanisms of action are hitherto poorly characterized. This hampers our understanding of therapy resistance, frequently occurring in leukemia despite the current therapeutic combinations using glucocorticoids in acute lymphoblastic leukemia. In this review, we initially cover the traditional view of glucocorticoid resistance and ways of targeting this resistance. We discuss recent progress in our understanding of chromatin and posttranslational properties of the glucocorticoid receptor that might be proven beneficial in our efforts to understand and target therapy resistance. We discuss emerging roles of pathways and proteins such as the lymphocyte-specific kinase that antagonizes glucocorticoid receptor activation and nuclear translocation. In addition, we provide an overview of ongoing therapeutic approaches that sensitize cells to glucocorticoids including small molecule inhibitors and proteolysis-targeting chimeras.
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Affiliation(s)
- Cristina Borin
- Department of Biomolecular Medicine, Ghent University, Belgium
- Center for Medical Genetics, Ghent University and University Hospital, Belgium
- Cancer Research Institute Ghent (CRIG), Belgium
| | - Tim Pieters
- Department of Biomolecular Medicine, Ghent University, Belgium
- Center for Medical Genetics, Ghent University and University Hospital, Belgium
- Cancer Research Institute Ghent (CRIG), Belgium
| | - Valentina Serafin
- Department of Surgery Oncology and Gastroenterology, Oncology and Immunology Section, University of Padova, Italy
| | - Panagiotis Ntziachristos
- Department of Biomolecular Medicine, Ghent University, Belgium
- Center for Medical Genetics, Ghent University and University Hospital, Belgium
- Cancer Research Institute Ghent (CRIG), Belgium
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3
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Frew AJ, Corry DB. Glucocorticoids. Clin Immunol 2023. [DOI: 10.1016/b978-0-7020-8165-1.00083-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/08/2023]
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4
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Backe SJ, Sager RA, Regan BR, Sit J, Major LA, Bratslavsky G, Woodford MR, Bourboulia D, Mollapour M. A specialized Hsp90 co-chaperone network regulates steroid hormone receptor response to ligand. Cell Rep 2022; 40:111039. [PMID: 35830801 PMCID: PMC9306012 DOI: 10.1016/j.celrep.2022.111039] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 04/25/2022] [Accepted: 06/10/2022] [Indexed: 12/29/2022] Open
Abstract
Heat shock protein-90 (Hsp90) chaperone machinery is involved in the stability and activity of its client proteins. The chaperone function of Hsp90 is regulated by co-chaperones and post-translational modifications. Although structural evidence exists for Hsp90 interaction with clients, our understanding of the impact of Hsp90 chaperone function toward client activity in cells remains elusive. Here, we dissect the impact of recently identified higher eukaryotic co-chaperones, FNIP1/2 (FNIPs) and Tsc1, toward Hsp90 client activity. Our data show that Tsc1 and FNIP2 form mutually exclusive complexes with FNIP1, and that unlike Tsc1, FNIP1/2 interact with the catalytic residue of Hsp90. Functionally, these co-chaperone complexes increase the affinity of the steroid hormone receptors glucocorticoid receptor and estrogen receptor to their ligands in vivo. We provide a model for the responsiveness of the steroid hormone receptor activation upon ligand binding as a consequence of their association with specific Hsp90:co-chaperone subpopulations.
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Affiliation(s)
- Sarah J Backe
- Department of Urology, SUNY Upstate Medical University, Syracuse, NY 13210, USA; Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY 13210, USA; Upstate Cancer Center, SUNY Upstate Medical University, Syracuse, NY 13210, USA
| | - Rebecca A Sager
- Department of Urology, SUNY Upstate Medical University, Syracuse, NY 13210, USA; Upstate Cancer Center, SUNY Upstate Medical University, Syracuse, NY 13210, USA
| | - Bethany R Regan
- Department of Urology, SUNY Upstate Medical University, Syracuse, NY 13210, USA; Upstate Cancer Center, SUNY Upstate Medical University, Syracuse, NY 13210, USA; College of Medicine, SUNY Upstate Medical University, Syracuse, NY 13210, USA
| | - Julian Sit
- Department of Urology, SUNY Upstate Medical University, Syracuse, NY 13210, USA; Upstate Cancer Center, SUNY Upstate Medical University, Syracuse, NY 13210, USA; College of Medicine, SUNY Upstate Medical University, Syracuse, NY 13210, USA
| | - Lauren A Major
- Department of Urology, SUNY Upstate Medical University, Syracuse, NY 13210, USA; Upstate Cancer Center, SUNY Upstate Medical University, Syracuse, NY 13210, USA; College of Medicine, SUNY Upstate Medical University, Syracuse, NY 13210, USA
| | - Gennady Bratslavsky
- Department of Urology, SUNY Upstate Medical University, Syracuse, NY 13210, USA; Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY 13210, USA; Upstate Cancer Center, SUNY Upstate Medical University, Syracuse, NY 13210, USA
| | - Mark R Woodford
- Department of Urology, SUNY Upstate Medical University, Syracuse, NY 13210, USA; Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY 13210, USA; Upstate Cancer Center, SUNY Upstate Medical University, Syracuse, NY 13210, USA
| | - Dimitra Bourboulia
- Department of Urology, SUNY Upstate Medical University, Syracuse, NY 13210, USA; Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY 13210, USA; Upstate Cancer Center, SUNY Upstate Medical University, Syracuse, NY 13210, USA
| | - Mehdi Mollapour
- Department of Urology, SUNY Upstate Medical University, Syracuse, NY 13210, USA; Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY 13210, USA; Upstate Cancer Center, SUNY Upstate Medical University, Syracuse, NY 13210, USA.
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Galigniana MD. Molecular Pharmacology of the Youngest Member of the Nuclear Receptor Family: The Mineralocorticoid Receptor. NUCLEAR RECEPTORS 2021:1-21. [DOI: 10.1007/978-3-030-78315-0_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
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6
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Liberman AC, Budziñski ML, Sokn C, Gobbini RP, Ugo MB, Arzt E. SUMO conjugation as regulator of the glucocorticoid receptor-FKBP51 cellular response to stress. Steroids 2020; 153:108520. [PMID: 31604074 DOI: 10.1016/j.steroids.2019.108520] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 08/20/2019] [Accepted: 10/01/2019] [Indexed: 01/19/2023]
Abstract
In order to adequately respond to stressful stimuli, glucocorticoids (GCs) target almost every tissue of the body. By exerting a negative feedback loop in the hypothalamic-pituitary-adrenal (HPA) axis GCs inhibit their own synthesis and restore homeostasis. GCs actions are mostly mediated by the GC receptor (GR), a member of the nuclear receptor superfamily. Alterations of the GR activity have been associatedto different diseases including mood disorders and can lead to severe complication. Therefore, understanding the molecular complexity of GR modulation is mandatory for the development of new and effective drugs for treating GR-associated disorders. FKBP51 is a GR chaperone that has gained much attention because it is a strong inhibitor of GR activity and has a crucial role in psychiatric diseases. Both GR and FKBP51 activity are regulated by SUMOylation, a posttranslational (PTM). In this review, we focus on the impact of SUMO-conjugation as a regulator of this pathway.
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Affiliation(s)
- Ana C Liberman
- Instituto de Investigación en Biomedicina de Buenos Aires (IBioBA)- CONICET - Partner Institute of the Max Planck Society, Buenos Aires C1425FQD, Argentina.
| | - Maia L Budziñski
- Instituto de Investigación en Biomedicina de Buenos Aires (IBioBA)- CONICET - Partner Institute of the Max Planck Society, Buenos Aires C1425FQD, Argentina
| | - Clara Sokn
- Instituto de Investigación en Biomedicina de Buenos Aires (IBioBA)- CONICET - Partner Institute of the Max Planck Society, Buenos Aires C1425FQD, Argentina
| | - Romina P Gobbini
- Instituto de Investigación en Biomedicina de Buenos Aires (IBioBA)- CONICET - Partner Institute of the Max Planck Society, Buenos Aires C1425FQD, Argentina
| | - Maria B Ugo
- Instituto de Investigación en Biomedicina de Buenos Aires (IBioBA)- CONICET - Partner Institute of the Max Planck Society, Buenos Aires C1425FQD, Argentina
| | - Eduardo Arzt
- Instituto de Investigación en Biomedicina de Buenos Aires (IBioBA)- CONICET - Partner Institute of the Max Planck Society, Buenos Aires C1425FQD, Argentina; Departamento de Fisiología y Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires C1428EGA, Argentina.
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Morishima Y, Mehta RK, Yoshimura M, Lau M, Southworth DR, Lawrence TS, Pratt WB, Nyati MK, Osawa Y. Chaperone Activity and Dimerization Properties of Hsp90 α and Hsp90 β in Glucocorticoid Receptor Activation by the Multiprotein Hsp90/Hsp70-Dependent Chaperone Machinery. Mol Pharmacol 2018; 94:984-991. [PMID: 29941666 DOI: 10.1124/mol.118.112516] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 06/20/2018] [Indexed: 11/22/2022] Open
Abstract
Several hundred proteins cycle into heterocomplexes with a dimer of the chaperone heat shock protein 90 (Hsp90), regulating their activity and turnover. There are two isoforms of Hsp90, Hsp90α and Hsp90β, and their relative chaperone activities and composition in these client protein•Hsp90 heterocomplexes has not been determined. Here, we examined the activity of human Hsp90α and Hsp90β in a purified five-protein chaperone machinery that assembles glucocorticoid receptor (GR)•Hsp90 heterocomplexes to generate high-affinity steroid-binding activity. We found that human Hsp90α and Hsp90β have equivalent chaperone activities, and when mixed together in this assay, they formed only GR•Hsp90αα and GR•Hsp90ββ homodimers and no GR•Hsp90αβ heterodimers. In contrast, GR•Hsp90 heterocomplexes formed in human embryonic kidney (HEK) cells also contain GR•Hsp90αβ heterodimers. The formation of GR•Hsp90αβ heterodimers in HEK cells probably reflects the longer time permitted for exchange to form Hsp90αβ heterodimers in the cell versus in the cell-free assembly conditions. This purified GR-activating chaperone machinery can be used to determine how modifications of Hsp90 affect its chaperone activity. To that effect, we have tested whether the unique phosphorylation of Hsp90α at threonines 5 and 7 that occurs during DNA damage repair affects its chaperone activity. We showed that the phosphomimetic mutant Hsp90α T5/7D has the same intrinsic chaperone activity as wild-type human Hsp90α in activation of GR steroid-binding activity by the five-protein machinery, supporting the conclusion that T5/7 phosphorylation does not affect Hsp90α chaperone activity.
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Affiliation(s)
- Yoshihiro Morishima
- Departments of Pharmacology (Y.M., M.Y., M.L., W.B.P., Y.O.) and Radiation Oncology (R.K.M., T.S.L., M.K.N.), University of Michigan Medical School, Ann Arbor, Michigan; and Life Sciences Institute and Departments of Biochemistry and Biophysics, University of Michigan, Ann Arbor, Michigan (D.R.S.)
| | - Ranjit K Mehta
- Departments of Pharmacology (Y.M., M.Y., M.L., W.B.P., Y.O.) and Radiation Oncology (R.K.M., T.S.L., M.K.N.), University of Michigan Medical School, Ann Arbor, Michigan; and Life Sciences Institute and Departments of Biochemistry and Biophysics, University of Michigan, Ann Arbor, Michigan (D.R.S.)
| | - Miyako Yoshimura
- Departments of Pharmacology (Y.M., M.Y., M.L., W.B.P., Y.O.) and Radiation Oncology (R.K.M., T.S.L., M.K.N.), University of Michigan Medical School, Ann Arbor, Michigan; and Life Sciences Institute and Departments of Biochemistry and Biophysics, University of Michigan, Ann Arbor, Michigan (D.R.S.)
| | - Miranda Lau
- Departments of Pharmacology (Y.M., M.Y., M.L., W.B.P., Y.O.) and Radiation Oncology (R.K.M., T.S.L., M.K.N.), University of Michigan Medical School, Ann Arbor, Michigan; and Life Sciences Institute and Departments of Biochemistry and Biophysics, University of Michigan, Ann Arbor, Michigan (D.R.S.)
| | - Daniel R Southworth
- Departments of Pharmacology (Y.M., M.Y., M.L., W.B.P., Y.O.) and Radiation Oncology (R.K.M., T.S.L., M.K.N.), University of Michigan Medical School, Ann Arbor, Michigan; and Life Sciences Institute and Departments of Biochemistry and Biophysics, University of Michigan, Ann Arbor, Michigan (D.R.S.)
| | - Theodore S Lawrence
- Departments of Pharmacology (Y.M., M.Y., M.L., W.B.P., Y.O.) and Radiation Oncology (R.K.M., T.S.L., M.K.N.), University of Michigan Medical School, Ann Arbor, Michigan; and Life Sciences Institute and Departments of Biochemistry and Biophysics, University of Michigan, Ann Arbor, Michigan (D.R.S.)
| | - William B Pratt
- Departments of Pharmacology (Y.M., M.Y., M.L., W.B.P., Y.O.) and Radiation Oncology (R.K.M., T.S.L., M.K.N.), University of Michigan Medical School, Ann Arbor, Michigan; and Life Sciences Institute and Departments of Biochemistry and Biophysics, University of Michigan, Ann Arbor, Michigan (D.R.S.)
| | - Mukesh K Nyati
- Departments of Pharmacology (Y.M., M.Y., M.L., W.B.P., Y.O.) and Radiation Oncology (R.K.M., T.S.L., M.K.N.), University of Michigan Medical School, Ann Arbor, Michigan; and Life Sciences Institute and Departments of Biochemistry and Biophysics, University of Michigan, Ann Arbor, Michigan (D.R.S.)
| | - Yoichi Osawa
- Departments of Pharmacology (Y.M., M.Y., M.L., W.B.P., Y.O.) and Radiation Oncology (R.K.M., T.S.L., M.K.N.), University of Michigan Medical School, Ann Arbor, Michigan; and Life Sciences Institute and Departments of Biochemistry and Biophysics, University of Michigan, Ann Arbor, Michigan (D.R.S.)
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8
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Cox MB, Johnson JL. Evidence for Hsp90 Co-chaperones in Regulating Hsp90 Function and Promoting Client Protein Folding. Methods Mol Biol 2018; 1709:397-422. [PMID: 29177674 DOI: 10.1007/978-1-4939-7477-1_28] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Molecular chaperones are a diverse group of highly conserved proteins that transiently interact with partially folded polypeptide chains during normal cellular processes such as protein translation, translocation, and disassembly of protein complexes. Prior to folding or after denaturation, hydrophobic residues that are normally sequestered within a folded protein are exposed to the aqueous environment and are prone to aggregation or misfolding. Multiple classes of molecular chaperones, such as Hsp70s and Hsp40s, recognize and transiently bind polypeptides with exposed hydrophobic stretches in order to prevent misfolding. Other types of chaperones, such as Hsp90, have more specialized functions in that they appear to interact with only a subset of cellular proteins. This chapter focuses on the role of Hsp90 and partner co-chaperones in promoting the folding and activation of a diverse group of proteins with critical roles in cellular signaling and function.
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Affiliation(s)
- Marc B Cox
- Department of Biological Sciences, University of Texas at El Paso and the Border Biomedical Research Center, El Paso, TX, 79968, USA
| | - Jill L Johnson
- Department of Biological Sciences and the Center for Reproductive Biology, University of Idaho, Moscow, ID, 83844-3051, USA.
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9
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Turrin NP, Rivest S. Unraveling the Molecular Details Involved in the Intimate Link between the Immune and Neuroendocrine Systems. Exp Biol Med (Maywood) 2016; 229:996-1006. [PMID: 15522835 DOI: 10.1177/153537020422901003] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
During systemic infections, the immune system can signal the brain and act on different neuronal circuits via soluble molecules, such as proinflammatory cytokines, that act on the cells forming the blood-brain barrier and the circumventricular organs. These activated cells release prostaglandin of the E2 type (PGE2), which is the endogenous ligand that triggers the pathways involved in the control of autonomic functions necessary to restore homeostasis and provide inhibitory feedback to innate immunity. Among these neurophysiological functions, activation of the circuits that control the plasma release of glucocorticoids is probably the most critical to the survival of the host in the presence of pathogens. This review revisits this issue and describes in depth the molecular details (including the emerging role of Toll-like receptors during inflammation) underlying the influence of circulating inflammatory molecules on the cerebral tissue, focusing on their contribution in the synthesis and action PGE2 in the brain. We also provide an innovative view supporting the concept of “fast and delayed response” involving the same ligands but different groups of cells, signal transduction pathways, and target genes.
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Affiliation(s)
- Nicolas P Turrin
- Laboratory of Molecular Endocrinology, CHUL Research Center and Department of Anatomy and Physiology, Laval University, 2705 Boulevard Laurier, Québec G1V 4G2, Canada
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Alam SB, Rochon D. Cucumber Necrosis Virus Recruits Cellular Heat Shock Protein 70 Homologs at Several Stages of Infection. J Virol 2015; 90:3302-17. [PMID: 26719261 PMCID: PMC4794660 DOI: 10.1128/jvi.02833-15] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Accepted: 12/16/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED RNA viruses often depend on host factors for multiplication inside cells due to the constraints of their small genome size and limited coding capacity. One such factor that has been exploited by several plant and animal viruses is heat shock protein 70 (HSP70) family homologs which have been shown to play roles for different viruses in viral RNA replication, viral assembly, disassembly, and cell-to-cell movement. Using next generation sequence analysis, we reveal that several isoforms of Hsp70 and Hsc70 transcripts are induced to very high levels during cucumber necrosis virus (CNV) infection of Nicotiana benthamiana and that HSP70 proteins are also induced by at least 10-fold. We show that HSP70 family protein homologs are co-opted by CNV at several stages of infection. We have found that overexpression of Hsp70 or Hsc70 leads to enhanced CNV genomic RNA, coat protein (CP), and virion accumulation, whereas downregulation leads to a corresponding decrease. Hsc70-2 was found to increase solubility of CNV CP in vitro and to increase accumulation of CNV CP independently of viral RNA replication during coagroinfiltration in N. benthamiana. In addition, virus particle assembly into virus-like particles in CP agroinfiltrated plants was increased in the presence of Hsc70-2. HSP70 was found to increase the targeting of CNV CP to chloroplasts during infection, reinforcing the role of HSP70 in chloroplast targeting of host proteins. Hence, our findings have led to the discovery of a highly induced host factor that has been co-opted to play multiple roles during several stages of the CNV infection cycle. IMPORTANCE Because of the small size of its RNA genome, CNV is dependent on interaction with host cellular components to successfully complete its multiplication cycle. We have found that CNV induces HSP70 family homologs to a high level during infection, possibly as a result of the host response to the high levels of CNV proteins that accumulate during infection. Moreover, we have found that CNV co-opts HSP70 family homologs to facilitate several aspects of the infection process such as viral RNA, coat protein and virus accumulation. Chloroplast targeting of the CNV CP is also facilitated, which may aid in CNV suppression of host defense responses. Several viruses have been shown to induce HSP70 during infection and others to utilize HSP70 for specific aspects of infection such as replication, assembly, and disassembly. We speculate that HSP70 may play multiple roles in the infection processes of many viruses.
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Affiliation(s)
- Syed Benazir Alam
- Faculty of Land and Food Systems, University of British Columbia, Vancouver, British Columbia, Canada
| | - D'Ann Rochon
- Faculty of Land and Food Systems, University of British Columbia, Vancouver, British Columbia, Canada Summerland Research and Development Centre, Agriculture and Agri-Food Canada, Summerland, British Columbia, Canada
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Mazaira GI, Lagadari M, Erlejman AG, Galigniana MD. The Emerging Role of TPR-Domain Immunophilins in the Mechanism of Action of Steroid Receptors. NUCLEAR RECEPTOR RESEARCH 2014. [DOI: 10.11131/2014/101094] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Affiliation(s)
- G. I. Mazaira
- Departamento de Química Biológica-IQUIBICEN, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - M. Lagadari
- Instituto de Biología y Medicina Experimental, CONICET, Buenos Aires, Argentina
| | - A. G. Erlejman
- Departamento de Química Biológica-IQUIBICEN, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - M. D. Galigniana
- Departamento de Química Biológica-IQUIBICEN, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
- Instituto de Biología y Medicina Experimental, CONICET, Buenos Aires, Argentina
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12
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Increased resistance of immobilized-stressed mice to infection: correlation with behavioral alterations. Brain Behav Immun 2013; 28:115-27. [PMID: 23142705 DOI: 10.1016/j.bbi.2012.11.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Revised: 11/01/2012] [Accepted: 11/01/2012] [Indexed: 01/07/2023] Open
Abstract
Immobilization is an easy and convenient method to induce both psychological and physical stress resulting in restricted motility and aggression and is believed to be the most severe type of stress in rodent models. Although it has been generally accepted that chronic stress often results in immunosuppression while acute stress has been shown to enhance immune responses, the effects of IS on the host resistance to Escherichia coli (E. coli) infection and associated behavioral changes are still not clear. In a series of experiments aimed at determining the level of hypothalamic COX-2, HSP-90, HSP-70, SOD-1 and plasma level of corticosterone, cytokine, antibody titer and their association with behavioral activities, mice were infected with viable E. coli during acute and chronic IS by taping their paws. In this study we show that acute and chronic IS enhances the resistance of mice to E. coli infection via inhibiting the production of pro-inflammatory cytokines, free radicals, and by improving the exploratory behavior. Altogether, our findings support the notion that cytokines released during immune activation and under the influence of corticosterone can modulate the open field behavior both in terms of locomotor activity as well as exploration. One of the features observed with chronic stressor was a lower ability to resist bacterial infection, although in case of acute stress, a better clearance of bacterial infection was observed in vivo with improvement of exploratory behavior and cognitive functions.
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13
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Buttgereit F, Seibel MJ, Bijlsma JW. Glucocorticoids. Clin Immunol 2013. [DOI: 10.1016/b978-0-7234-3691-1.00100-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Quintá HR, Galigniana MD. The neuroregenerative mechanism mediated by the Hsp90-binding immunophilin FKBP52 resembles the early steps of neuronal differentiation. Br J Pharmacol 2012; 166:637-49. [PMID: 22091865 DOI: 10.1111/j.1476-5381.2011.01783.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE The immunosuppressive macrolide FK506 (tacrolimus) shows neuroregenerative action by a mechanism that appears to involve the Hsp90-binding immunophilin FKBP52. This study analyses some aspects of the early steps of neuronal differentiation and neuroregeneration. EXPERIMENTAL APPROACH Undifferentiated murine neuroblastoma cells and hippocampal neurones isolated from embryonic day-17 rat embryos were induced to differentiate with FK506. Subcellular relocalization of FKBP52, Hsp90 and its co-chaperone p23 was analysed by indirect immunofluorescence confocal microscopy and by Western blots of axonal fractions isolated from cells grown on a porous transwell cell culture chamber. Neuroregeneration was evaluated using a scratch-wound assay. KEY RESULTS In undifferentiated cells, FKBP52, Hsp90 and p23 are located in the cell nucleus, forming an annular structure that disassembles when the differentiation process is triggered by FK506. This was observed in the N2a cell line and in hippocampal neurones. More importantly, the annular structure of chaperones is reassembled after damaging the neurones, whereas FK506 prompts their rapid regeneration, a process linked to the subcellular redistribution of the heterocomplex. CONCLUSIONS AND IMPLICATIONS There is a direct relationship between the disassembly of the chaperone complex and the progression of neuronal differentiation upon stimulation with the immunophilin ligand FK506. Both neuronal differentiation and neuroregeneration appear to be mechanistically linked, so the elucidation of one mechanism may lead to unravel the properties of the other. This study also implies that the discovery of FK506 derivatives, devoid of immunosuppressive action, would be therapeutically significant for neurotrophic use.
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Affiliation(s)
- H R Quintá
- Instituto de Biología y Medicina Experimental-CONICET and Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
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15
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Johnston PA, Shinde SN, Hua Y, Shun TY, Lazo JS, Day BW. Development and validation of a high-content screening assay to identify inhibitors of cytoplasmic dynein-mediated transport of glucocorticoid receptor to the nucleus. Assay Drug Dev Technol 2012; 10:432-56. [PMID: 22830992 DOI: 10.1089/adt.2012.456] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Rapid ligand-induced trafficking of glucocorticoid nuclear hormone receptor (GR) from the cytoplasm to the nucleus is an extensively studied model for intracellular retrograde cargo transport employed in constructive morphogenesis and many other cellular functions. Unfortunately, potent and selective small-molecule disruptors of this process are lacking, which has restricted pharmacological investigations. We describe here the development and validation of a 384-well high-content screening (HCS) assay to identify inhibitors of the rapid ligand-induced retrograde translocation of cytoplasmic glucocorticoid nuclear hormone receptor green fluorescent fusion protein (GR-GFP) into the nuclei of 3617.4 mouse mammary adenocarcinoma cells. We selected 3617.4 cells, because they express GR-GFP under the control of a tetracycline (Tet)-repressible promoter and are exceptionally amenable to image acquisition and analysis procedures. Initially, we investigated the time-dependent expression of GR-GFP in 3617.4 cells under Tet-on and Tet-off control to determine the optimal conditions to measure dexamethasone (Dex)-induced GR-GFP nuclear translocation on the ArrayScan-VTI automated imaging platform. We then miniaturized the assay into a 384-well format and validated the performance of the GR-GFP nuclear translocation HCS assay in our 3-day assay signal window and dimethylsulfoxide validation tests. The molecular chaperone heat shock protein 90 (Hsp90) plays an essential role in the regulation of GR steroid binding affinity and ligand-induced retrograde trafficking to the nucleus. We verified that the GR-GFP HCS assay captured the concentration-dependent inhibition of GR-GFP nuclear translocation by 17-AAG, a benzoquinone ansamycin that selectively blocks the binding and hydrolysis of ATP by Hsp90. We screened the 1280 compound library of pharmacologically active compounds set in the Dex-induced GR-GFP nuclear translocation assay and used the multi-parameter HCS data to eliminate cytotoxic compounds and fluorescent outliers. We identified five qualified hits that inhibited the rapid retrograde trafficking of GR-GFP in a concentration-dependent manner: Bay 11-7085, 4-phenyl-3-furoxancarbonitrile, parthenolide, apomorphine, and 6-nitroso-1,2-benzopyrone. The data presented here demonstrate that the GR-GFP HCS assay provides an effective phenotypic screen and support the proposition that screening a larger library of diversity compounds will yield novel small-molecule probes that will enable the further exploration of intracellular retrograde transport of cargo along microtubules, a process which is essential to the morphogenesis and function of all cells.
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Affiliation(s)
- Paul A Johnston
- School of Medicine, University of Pittsburgh Drug Discovery Institute, Pittsburgh, Pennsylvania, USA
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16
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Galigniana MD, Echeverría PC, Erlejman AG, Piwien-Pilipuk G. Role of molecular chaperones and TPR-domain proteins in the cytoplasmic transport of steroid receptors and their passage through the nuclear pore. Nucleus 2012; 1:299-308. [PMID: 21113270 DOI: 10.4161/nucl.1.4.11743] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
In the absence of hormone, corticosteroid receptors such as GR (glucocorticoid receptor) and (mineralocorticoid receptor) are primarily located in the cytoplasm. Upon steroid-binding, they rapidly accumulate in the nucleus. Regardless of their primary location, these receptors and many other nuclear factors undergo a constant and dynamic nucleocytoplasmic shuttling. All members of the steroid receptor family are known to form large oligomeric structures with the heat-shock proteins of 90-kDa (hsp90) and 70-kDa (hsp70), the small acidic protein p23, and a tetratricopeptide repeat (TPR) -domain protein such as FK506-binding proteins (FKBPs), cyclophilins (CyPs) or the serine/threonine protein phosphatase 5 (PP5). It has always been stated that the dissociation of the chaperone heterocomplex (a process normally referred to as receptor "transformation") is the first step that permits the nuclear import of steroid receptors. However the experimental evidence is consistent with a model where the chaperone machinery is required for the retrotransport of the receptor through the cytoplasm and also facilitates the passage through the nuclear pore. Recent evidence indicates that the hsp90-based chaperone system also interacts with structures of the nuclear pore such as importin β and the integral nuclear pore glycoprotein Nup62 facilitating the passage of the untransformed receptor through the nuclear pore.
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Affiliation(s)
- Mario D Galigniana
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina.
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17
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Cassel JA, Ilyin S, McDonnell ME, Reitz AB. Novel inhibitors of heat shock protein Hsp70-mediated luciferase refolding that bind to DnaJ. Bioorg Med Chem 2012; 20:3609-14. [PMID: 22546203 DOI: 10.1016/j.bmc.2012.03.067] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Revised: 03/22/2012] [Accepted: 03/29/2012] [Indexed: 01/07/2023]
Abstract
Inhibitors of both heat shock proteins Hsp90 and Hsp70 have been identified in assays measuring luciferase refolding containing rabbit reticulocyte lysate or purified chaperone components. Here, we report the discovery of a series of phenoxy-N-arylacetamides that disrupt Hsp70-mediated luciferase refolding by binding to DnaJ, the bacterial homolog of human Hsp40. Inhibitor characterization experiments demonstrated negative cooperativity with respect to DnaJ and luciferase concentration, but varying the concentration of ATP had no effect on potency. Thermal shift analysis suggested a direct interaction with DnaJ, but not with Hsp70. These compounds may be useful tools for studying DnaJ/Hsp40 in various cellular processes.
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Affiliation(s)
- Joel A Cassel
- ALS Biopharma, LLC, Pennsylvania Biotechnology Center, 3805 Old Easton Rd, Doylestown, PA 18902, USA.
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18
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Murphy PJM, Franklin HR, Furukawa NW. Biochemical reconstitution of steroid receptor•Hsp90 protein complexes and reactivation of ligand binding. J Vis Exp 2011:3059. [PMID: 21968922 DOI: 10.3791/3059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Hsp90 is an essential and highly abundant molecular chaperone protein that has been found to regulate more than 150 eukaryotic signaling proteins, including transcription factors (e.g. nuclear receptors, p53) and protein kinases (e.g. Src, Raf, Akt kinase) involved in cell cycling, tumorigenesis, apoptosis, and multiple eukaryotic signaling pathways (1,2). Of these many 'client' proteins for hsp90, the assembly of steroid receptor•hsp90 complexes is the best defined (Figure 1). We present here an adaptable glucocorticoid receptor (GR) immunoprecipitation assay and in vitro GR•hsp90 reconstitution method that may be readily used to probe eukaryotic hsp90 functional activity, hsp90-mediated steroid receptor ligand binding, and molecular chaperone cofactor requirements. For example, this assay can be used to test hsp90 cofactor requirements and the effects of adding exogenous compounds to the reconstitution process. The GR has been a particularly useful system for studying hsp90 because the receptor must be bound to hsp90 to have an open ligand binding cleft that is accessible to steroid (3). Endogenous, unliganded GR is present in the cytoplasm of mammalian cells noncovalently bound to hsp90. As found in the endogenous GR•hsp90 heterocomplex, the GR ligand binding cleft is open and capable of binding steroid. If hsp90 dissociates from the GR or if its function is inhibited, the receptor is unable to bind steroid and requires reconstitution of the GR•hsp90 heterocomplex before steroid binding activity is restored (4) . GR can be immunoprecipitated from cell cytosol using a monoclonal antibody, and proteins such as hsp90 complexed to the GR can be assayed by western blot. Steroid binding activity of the immunoprecipitated GR can be determined by incubating the immunopellet with [(3)H]steroid. Previous experiments have shown hsp90-mediated opening of the GR ligand binding cleft requires hsp70, a second molecular chaperone also essential for eukaryotic cell viability. Biochemical activity of hsp90 and hsp70 are catalyzed by co-chaperone proteins Hop, hsp40, and p23 (5). A multiprotein chaperone machinery containing hsp90, hsp70, Hop, and hsp40 are endogenously present in eukaryotic cell cytoplasm, and reticulocyte lysate provides a chaperone-rich protein source (6). In the method presented, GR is immunoadsorbed from cell cytosol and stripped of the endogenous hsp90/hsp70 chaperone machinery using mild salt conditions. The salt-stripped GR is then incubated with reticulocyte lysate, ATP, and K(+), which results in the reconstitution of the GR•hsp90 heterocomplex and reactivation of steroid binding activity (7). This method can be utilized to test the effects of various chaperone cofactors, novel proteins, and experimental hsp90 or GR inhibitors in order to determine their functional significance on hsp90-mediated steroid binding (8-11).
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Affiliation(s)
- Patrick J M Murphy
- College of Nursing, Interdisciplinary Life Sciences Research Laboratory, Seattle University, WA, USA
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19
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Daghestani HN, Zhu G, Johnston PA, Shinde SN, Brodsky JL, Day BW. Characterization of inhibitors of glucocorticoid receptor nuclear translocation: a model of cytoplasmic dynein-mediated cargo transport. Assay Drug Dev Technol 2011; 10:46-60. [PMID: 21919741 DOI: 10.1089/adt.2010.0367] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Agonist-induced glucocorticoid receptor [GR] transport from the cytoplasm to the nucleus was used as a model to identify dynein-mediated cargo transport inhibitors. Cell-based screening of the library of pharmacologically active compound (LOPAC)-1280 collection identified several small molecules that stalled the agonist-induced transport of GR-green fluorescent protein (GFP) in a concentration-dependent manner. Fluorescent images of microtubule organization, nuclear DNA staining, expression of GR-GFP, and its subcellular distribution were inspected and quantified by image analysis to evaluate the impact of compounds on cell morphology, toxicity, and GR transport. Given the complexity of the multi-protein complex involved in dynein-mediated cargo transport and the variety of potential mechanisms for interruption of that process, we therefore developed and validated a panel of biochemical assays to investigate some of the more likely intracellular target(s) of the GR transport inhibitors. Although the apomorphine enantiomers exhibited the most potency toward the ATPase activities of cytoplasmic dynein, myosin, and the heat-shock proteins (HSPs), their apparent lack of specificity made them unattractive for further study in our quest. Other molecules appeared to be nonspecific inhibitors that targeted reactive cysteines of proteins. Ideally, specific retrograde transport inhibitors would either target dynein itself or one of the other important proteins associated with the transport process. Although the hits from the cell-based screen of the LOPAC-1280 collection did not exhibit this desired profile, this screening platform provided a promising phenotypic system for the discovery of dynein/HSP modulators.
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Affiliation(s)
- Hikmat N Daghestani
- Department of Structural Biology, University of Pittsburgh , Pittsburgh, Pennsylvania 15261, USA
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20
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Murphy PJM, Shannon M, Goertz J. Visualization of recombinant DNA and protein complexes using atomic force microscopy. J Vis Exp 2011:3061. [PMID: 21788938 PMCID: PMC3196170 DOI: 10.3791/3061] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Atomic force microscopy (AFM) allows for the visualizing of individual proteins, DNA molecules, protein-protein complexes, and DNA-protein complexes. On the end of the microscope's cantilever is a nano-scale probe, which traverses image areas ranging from nanometers to micrometers, measuring the elevation of macromolecules resting on the substrate surface at any given point. Electrostatic forces cause proteins, lipids, and nucleic acids to loosely attach to the substrate in random orientations and permit imaging. The generated data resemble a topographical map, where the macromolecules resolve as three-dimensional particles of discrete sizes (Figure 1). Tapping mode AFM involves the repeated oscillation of the cantilever, which permits imaging of relatively soft biomaterials such as DNA and proteins. One of the notable benefits of AFM over other nanoscale microscopy techniques is its relative adaptability to visualize individual proteins and macromolecular complexes in aqueous buffers, including near-physiologic buffered conditions, in real-time, and without staining or coating the sample to be imaged. The method presented here describes the imaging of DNA and an immunoadsorbed transcription factor (i.e. the glucocorticoid receptor, GR) in buffered solution (Figure 2). Immunoadsorbed proteins and protein complexes can be separated from the immunoadsorbing antibody-bead pellet by competition with the antibody epitope and then imaged (Figure 2A). This allows for biochemical manipulation of the biomolecules of interest prior to imaging. Once purified, DNA and proteins can be mixed and the resultant interacting complex can be imaged as well. Binding of DNA to mica requires a divalent cation, such as Ni(2+) or Mg(2+), which can be added to sample buffers yet maintain protein activity. Using a similar approach, AFM has been utilized to visualize individual enzymes, including RNA polymerase and a repair enzyme, bound to individual DNA strands. These experiments provide significant insight into the protein-protein and DNA-protein biophysical interactions taking place at the molecular level. Imaging individual macromolecular particles with AFM can be useful for determining particle homogeneity and for identifying the physical arrangement of constituent components of the imaged particles. While the present method was developed for visualization of GR-chaperone protein complexes) and DNA strands to which the GR can bind, it can be applied broadly to imaging DNA and protein samples from a variety of sources.
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Affiliation(s)
- Patrick J M Murphy
- College of Nursing, Interdisciplinary Life Sciences Research Laboratory, Seattle University, USA.
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21
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Reply to Thornton and Carroll: Lamprey possess a highly specific corticosteroid signaling system. Proc Natl Acad Sci U S A 2011. [DOI: 10.1073/pnas.1015112108] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
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Cox MB, Johnson JL. The role of p23, Hop, immunophilins, and other co-chaperones in regulating Hsp90 function. Methods Mol Biol 2011; 787:45-66. [PMID: 21898226 DOI: 10.1007/978-1-61779-295-3_4] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Molecular chaperones are a diverse group of highly conserved proteins that transiently interact with partially folded polypeptide chains during normal cellular processes, such as protein translation, translocation, and disassembly of protein complexes (1). Prior to folding or after denaturation, hydrophobic residues that are normally sequestered within a folded protein are exposed to the aqueous environment and are prone to aggregation or misfolding. Multiple classes of molecular chaperones, such as Hsp70s and Hsp40s, recognize and transiently bind polypeptides with exposed hydrophobic stretches in order to prevent misfolding. Other types of chaperones, such as Hsp90, have more specialized functions in that they appear to interact with only a subset of cellular proteins. This chapter focuses on the role of Hsp90 and partner co-chaperones in promoting the folding and activation of a diverse group of proteins with critical roles in cellular signaling and function.
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Affiliation(s)
- Marc B Cox
- Department of Biological Sciences, University of Texas at El Paso, El Paso, TX, USA
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23
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Quintá HR, Maschi D, Gomez-Sanchez C, Piwien-Pilipuk G, Galigniana MD. Subcellular rearrangement of hsp90-binding immunophilins accompanies neuronal differentiation and neurite outgrowth. J Neurochem 2010; 115:716-34. [PMID: 20796173 DOI: 10.1111/j.1471-4159.2010.06970.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
FKBP51 and FKBP52 (FK506-binding protein 51 and 52) are tetratricopeptide repeat-domain immunophilins belonging to the tetratricopeptide-protein•hsp90•hsp70•p23 heterocomplex bound to steroid receptors. Immunophilins are related to receptor folding, subcellular localization, and hormone-dependent transcription. Also, they bind the immunosuppressant macrolide FK506, which shows neuroregenerative and neuroprotective actions by a still unknown mechanism. In this study, we demonstrate that in both, undifferentiated neuroblastoma cells and embryonic hippocampal neurons, the FKBP52•hsp90•p23 heterocomplex concentrates in a perinuclear structure. Upon cell stimulation with FK506, this structure disassembles and this perinuclear area becomes transcriptionally active. The acquisition of a neuronal phenotype is accompanied by increased expression of βIII-tubulin, Map-2, Tau-1, but also hsp90, hsp70, p23, and FKBP52. During the early differentiation steps, the perinuclear heterocomplex redistributes along the cytoplasm and nascent neurites, p23 binds to intermediate filaments and microtubules acquired higher filamentary organization. While FKBP52 moves towards neurites and concentrates in arborization bodies and terminal axons, FKBP51, whose expression remains constant, replaces FKBP52 in the perinuclear structure. Importantly, neurite outgrowth is favored by FKBP52 over-expression or FKBP51 knock-down, and is impaired by FKBP52 knock-down or FKBP51 over-expression, indicating that the balance between these FK506-binding proteins plays a key role during the early mechanism of neuronal differentiation.
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Affiliation(s)
- Héctor R Quintá
- Instituto de Biología y Medicina Experimental/CONICET, Buenos Aires, Argentina
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24
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Marwick JA, Adcock IM, Chung KF. Overcoming reduced glucocorticoid sensitivity in airway disease: molecular mechanisms and therapeutic approaches. Drugs 2010; 70:929-48. [PMID: 20481652 DOI: 10.2165/10898520-000000000-00000] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
There is a considerable and growing unmet medical need in respiratory disease concerning effective anti-inflammatory therapies for conditions such as severe asthma, chronic obstructive pulmonary disease and cystic fibrosis. These diseases share a predominant characteristic of an enhanced and uncontrolled inflammatory response in the lungs, which contributes to disease progression, hospitalization and mortality. These diseases are poorly controlled by current anti-inflammatory therapies including glucocorticoids, which are otherwise effective in many other inflammatory conditions or in milder disease such as asthma. The exact cause of this apparent impairment of glucocorticoid function remains largely unclear; however, recent studies have now implicated a number of possible mechanisms. Central among these is an elevation of the oxidant burden in the lungs and the resulting reduction in the activity of histone deacetylase (HDAC)-2. This contributes to both the enhancement of proinflammatory mediator expression and the impaired ability of the glucocorticoid receptor (GR)-alpha to repress proinflammatory gene expression. The oxidant-mediated reduction in HDAC-2 activity is, in part, a result of an elevation in the phosphoinositol 3-kinase (PI3K) delta/Akt signalling pathway. Blockade of the PI3Kdelta pathway restores glucocortiocoid function in both in vitro and in vivo models, and in primary cells from disease. In addition, inhibition of the PI3Kdelta and PI3Kgamma isoforms is anti-inflammatory in both innate and adaptive immune responses. Consequently, selective inhibition of this pathway may provide a therapeutic strategy both as a novel anti-inflammatory and in combination therapy with glucocorticoids to restore their function. However, a number of other oxidant-related and -unrelated mechanisms, including altered kinase signalling and expression of the dominant negative GRbeta, may also play a role in the development of glucocorticoid insensitivity. Further elucidation of these mechanisms and pathways will enable novel therapeutic targeting for alternative anti-inflammatory drugs or combination therapies providing restoration for the anti-inflammatory action of glucocorticoids.
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Affiliation(s)
- John A Marwick
- MRC Centre for Inflammation Research, Queens Medical Research Institute, University of Edinburgh Medical School, Edinburgh, UK.
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25
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Abstract
Corticosteroid hormones are critical for controlling metabolism, hydromineral balance, and the stress response in vertebrates. Although corticosteroid hormones have been well characterized in most vertebrate groups, the identity of the earliest vertebrate corticosteroid hormone has remained elusive. Here we provide evidence that 11-deoxycortisol is the corticosteroid hormone in the lamprey, a member of the agnathans that evolved more than 500 million years ago. We used RIA, HPLC, and mass spectrometry analysis to determine that 11-deoxycortisol is the active corticosteroid present in lamprey plasma. We also characterized an 11-deoxycortisol receptor extracted from sea lamprey gill cytosol. The receptor was highly specific for 11-deoxycortisol and exhibited corticosteroid binding characteristics, including DNA binding. Furthermore, we observed that 11-deoxycortisol was regulated by the hypothalamus-pituitary axis and responded to acute stress. 11-deoxycortisol implants reduced sex steroid concentrations and up-regulated gill Na+, K+-ATPase, an enzyme critical for ion balance. We show here that 11-deoxycortisol functioned as both a glucocorticoid and a mineralocorticoid in the lamprey. Our findings indicate that a complex and highly specific corticosteroid signaling pathway evolved at least 500 million years ago with the arrival of the earliest vertebrate.
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26
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Echeverria PC, Figueras MJ, Vogler M, Kriehuber T, de Miguel N, Deng B, Dalmasso MC, Matthews DE, Matrajt M, Haslbeck M, Buchner J, Angel SO. The Hsp90 co-chaperone p23 of Toxoplasma gondii: Identification, functional analysis and dynamic interactome determination. Mol Biochem Parasitol 2010; 172:129-40. [PMID: 20403389 DOI: 10.1016/j.molbiopara.2010.04.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2009] [Revised: 04/09/2010] [Accepted: 04/12/2010] [Indexed: 01/28/2023]
Abstract
Toxoplasma gondii is among the most successful parasites, with nearly half of the human population chronically infected. Recently a link between the T. gondii Hsp90 chaperone machinery and parasite development was observed. Here, the T. gondii Hsp90 co-chaperones p23 and Hip were identified mining the Toxoplasma- database (www.toxodb.org). Their identity was confirmed by domain structure and blast analysis. Additionally, analysis of the secondary structure and studies on the chaperone function of the purified protein verified the p23 identity. Studies of co-immunoprecipitation (co-IP) identified two different types of complexes, one comprising at least Hip-Hsp70-Hsp90 and another containing at least p23-Hsp90. Indirect immunofluorescence assays showed that Hip is localized in the cytoplasm in tachyzoites and as well in bradyzoites. For p23 in contrast, a solely cytoplasmic localization was only observed in the tachyzoite stage whereas nuclear and cytosolic distribution and co-localization with Hsp90 was observed in bradyzoites. These results indicate that the T. gondii Hsp90-heterocomplex cycle is similar to the one proposed for higher eukaryotes, further highlighting the implication of the Hsp90/p23 in parasite development. Furthermore, co-IP experiments of tachyzoite/bradyzoite lysates with anti-p23 antiserum and identification of the complexed proteins together with the use of the curated interaction data available from different source (orthologs and Plasmodium databases) allowed us to construct an interaction network (interactome) covering the dynamics of the Hsp90 chaperone machinery.
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Affiliation(s)
- Pablo C Echeverria
- Laboratorio de Parasitología Molecular, UB2, IIB-INTECH, CONICET-UNSAM, Camino de Circunvalación Laguna Km. 6, C.C 164, (B7130IIWA) Chascomús, Prov. Buenos Aires, Argentina
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Nuclear import of the glucocorticoid receptor-hsp90 complex through the nuclear pore complex is mediated by its interaction with Nup62 and importin beta. Mol Cell Biol 2009; 29:4788-97. [PMID: 19581287 DOI: 10.1128/mcb.00649-09] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Glucocorticoid receptor (GR) is cytoplasmic in the absence of ligand and localizes to the nucleus after steroid binding. Previous evidence demonstrated that the hsp90-based heterocomplex bound to GR is required for the efficient retrotransport of the receptor to the nuclear compartment. We examined the putative association of GR and its associated chaperone heterocomplex with structures of the nuclear pore. We found that importin beta and the integral nuclear pore glycoprotein Nup62 interact with hsp90, hsp70, p23, and the TPR domain proteins FKBP52 and PP5. Nup62 and GR were able to interact in a more efficient manner when chaperoned by the hsp90-based heterocomplex. Interestingly, the binding of hsp70 and p23 to Nup62 does not require the presence of hsp90, whereas the association of FKBP52 and PP5 is hsp90 dependent, as indicated by the results of experiments where the hsp90 function was disrupted with radicicol. The ability of both FKBP52 and PP5 to interact with Nup62 was abrogated in cells overexpressing the TPR peptide. Importantly, GR cross-linked to the hsp90 heterocomplex was able to translocate to the nucleus in digitonin-permeabilized cells treated with steroid, suggesting that GR could pass through the pore in its untransformed state.
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28
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Tell G, Quadrifoglio F, Tiribelli C, Kelley MR. The many functions of APE1/Ref-1: not only a DNA repair enzyme. Antioxid Redox Signal 2009; 11:601-20. [PMID: 18976116 PMCID: PMC2811080 DOI: 10.1089/ars.2008.2194] [Citation(s) in RCA: 358] [Impact Index Per Article: 23.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
APE1/Ref-1 (APE1), the mammalian ortholog of Escherichia coli Xth, and a multifunctional protein possessing both DNA repair and transcriptional regulatory activities, has a pleiotropic role in controlling cellular response to oxidative stress. APE1 is the main apurinic/apyrimidinic endonuclease in eukaryotic cells, playing a central role in the DNA base excision repair pathway of all DNA lesions (uracil, alkylated and oxidized, and abasic sites), including single-strand breaks, and has also cotranscriptional activity by modulating genes expression directly regulated by either ubiquitous (i.e., AP-1, Egr-1, NFkappa-B, p53, and HIF) and tissue specific (i.e., PEBP-2, Pax-5 and -8, and TTF-1) transcription factors. In addition, it controls the intracellular redox state by inhibiting the reactive oxygen species (ROS) production. At present, information is still inadequate regarding the molecular mechanisms responsible for the coordinated control of its several activities. Both expression and/or subcellular localization are altered in several metabolic and proliferative disorders such as in tumors and aging. Here, we have attempted to coalesce the most relevant information concerning APE1's different functions in order to shed new light and to focus current and future studies to fully understand this unique molecule that is acquiring more and more interest and translational relevance in the field of molecular medicine.
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Affiliation(s)
- Gianluca Tell
- Department of Biomedical Sciences and Technologies, University of Udine, Udine, Italy.
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29
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Pratt WB, Morishima Y, Osawa Y. The Hsp90 chaperone machinery regulates signaling by modulating ligand binding clefts. J Biol Chem 2008; 283:22885-9. [PMID: 18515355 PMCID: PMC2516982 DOI: 10.1074/jbc.r800023200] [Citation(s) in RCA: 118] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Affiliation(s)
- William B Pratt
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA
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Cintron NS, Toft D. Defining the requirements for Hsp40 and Hsp70 in the Hsp90 chaperone pathway. J Biol Chem 2006; 281:26235-44. [PMID: 16854979 DOI: 10.1074/jbc.m605417200] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The Hsp90 chaperoning pathway and its model client substrate, the progesterone receptor (PR), have been used extensively to study chaperone complex formation and maturation of a client substrate in a near native state. This chaperoning pathway can be reconstituted in vitro with the addition of five proteins plus ATP: Hsp40, Hsp70, Hop, Hsp90, and p23. The addition of these proteins is necessary to reconstitute hormone-binding capacity to the immuno-isolated PR. It was recently shown that the first step for the recognition of PR by this system is binding by Hsp40. We compared type I and type II Hsp40 proteins and created point mutations in Hsp40 and Hsp70 to understand the requirements for this first step. The type I proteins, Ydj1 and DjA1 (HDJ2), and a type II, DjB1 (HDJ1), act similarly in promoting hormone binding and Hsp70 association to PR, while having different binding characteristics to PR. Ydj1 and DjA1 bind tightly to PR whereas the binding of DjB1 apparently has rapid on and off rates and its binding cannot be observed by antibody pull-down methods using either purified proteins or cell lysates. Mutation studies indicate that client binding, interactions between Hsp40 and Hsp70, plus ATP hydrolysis by Hsp70 are all required to promote conformational maturation of PR via the Hsp90 pathway.
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Affiliation(s)
- Nela S Cintron
- Department of Biochemistry and Molecular Biology, Mayo Graduate School, Mayo Clinic and Foundation, Rochester, Minnesota 55905, USA
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Li R, Soosairajah J, Harari D, Citri A, Price J, Ng HL, Morton CJ, Parker MW, Yarden Y, Bernard O. Hsp90 increases LIM kinase activity by promoting its homo-dimerization. FASEB J 2006; 20:1218-20. [PMID: 16641196 DOI: 10.1096/fj.05-5258fje] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
LIM kinase 1 (LIMK1) is a serine protein kinase that regulates the actin cytoskeleton by phosphorylation and inactivation of actin depolymerizing factor cofilin. LIMK1 activity is regulated by the Rho-GTPases via their serine/threonine kinase effectors Rho-kinase and p21-activated kinases 1 and 4 that phosphorylate LIMK1 on threonine 508 in its activation loop. The purpose of this study was to elucidate the pathway leading to the stability of LIMK1, a protein with a half-life of approximately 20 h. Because the half-life of kinase-dead LIMK1 is only 4 h, it is suggestive that trans- or auto-phosphorylation is responsible for the stabilization of LIMK1. Using known Hsp90 inhibitors, we have shown that the half-life of LIMK1 in cells depends on the presence of active Hsp90. Furthermore, endogenous LIMK1 coimmunoprecipitated with endogenous Hsp90 and this interaction promoted LIMK1 homodimer formation as seen by cross-linking experiments. Hsp90 binds LIMK1 via a recognition sequence within the LIMK1 kinase domain, homologous to that of ErbB-2. Mutation of a proline residue within this sequence to glutamic acid reduces its interaction with Hsp90, inhibits homodimer formation, and reduces its half-life to 4 h. These findings implicate Hsp90 in the stabilization of LIMK1 by promoting homodimer formation and transphosphorylation.
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Affiliation(s)
- Rong Li
- The Walter and Eliza Hall Institute of Medical Research, Victoria, Australia
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33
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Abstract
A multiprotein hsp90/hsp70-based chaperone machinery functions as a 'cradle-to-grave' system for regulating the steroid binding, trafficking and turnover of the glucocorticoid receptor (GR). In an ATP-dependent process where hsp70 and hsp90 act as essential chaperones and Hop, hsp40, and p23 act as nonessential co-chaperones, the machinery assembles complexes between the ligand binding domain of the GR and hsp90. During GR-hsp90 heterocomplex assembly, the hydrophobic ligand-binding cleft is opened to access by steroid, and subsequent binding of steroid within the cleft triggers a transformation of the receptor such that it engages in more dynamic cycles of assembly/disassembly with hsp90 that are required for rapid dynein-dependent translocation to the nucleus. Within the nucleus, the hsp90 chaperone machinery plays a critical role both in GR movement to transcription regulatory sites and in the disassembly of regulatory complexes as the hormone level declines. The chaperone machinery also plays a critical role in stabilization of the GR to ubiquitylation and proteasomal degradation. The initial GR interaction with hsp70 appears to be critical for the triage between hsp90 heterocomplex assembly and preservation of receptor function vs CHIP-dependent ubiquitylation and proteasomal degradation. The hsp90 chaperone machinery is ubiquitous and functionally conserved among eukaryotes, and it is possible that all physiologically significant actions of hsp90 require the hsp70-dependent assembly of client protein-hsp90 heterocomplexes.
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Affiliation(s)
- W B Pratt
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor 48109-0632, USA
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Van Craenenbroeck K, De Bosscher K, Vanden Berghe W, Vanhoenacker P, Haegeman G. Role of glucocorticoids in dopamine-related neuropsychiatric disorders. Mol Cell Endocrinol 2005; 245:10-22. [PMID: 16310935 DOI: 10.1016/j.mce.2005.10.007] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2005] [Accepted: 10/14/2005] [Indexed: 01/12/2023]
Abstract
'Psychoneuroendocrinology' is now quickly emerging as a hot interdisciplinary research field that addresses the interplay between neuronal and endocrine signaling in psychiatric diseases. Both glucocorticoid hormones and dopamine have an important role in maintaining normal brain functions. In this review, molecular and mechanistic aspects of glucocorticoid effects on brain function and behavior will be discussed with specific reference to dopamine signaling.
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Affiliation(s)
- Kathleen Van Craenenbroeck
- Laboratory for Eukaryotic Gene Expression and Signal Transduction, LEGEST, Department of Molecular Biology, Ghent University-UGent, K.L. Ledeganckstraat 35, 9000 Gent, Belgium
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35
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Murphy PJM. Regulation of glucocorticoid receptor steroid binding and trafficking by the hsp90/hsp70-based chaperone machinery: implications for clinical intervention. Leukemia 2005; 19:710-2. [PMID: 15759036 DOI: 10.1038/sj.leu.2403687] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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36
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Xu W, Yuan X, Xiang Z, Mimnaugh E, Marcu M, Neckers L. Surface charge and hydrophobicity determine ErbB2 binding to the Hsp90 chaperone complex. Nat Struct Mol Biol 2005; 12:120-6. [PMID: 15643424 DOI: 10.1038/nsmb885] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2004] [Accepted: 11/24/2004] [Indexed: 11/09/2022]
Abstract
The molecular chaperone Hsp90 modulates the function of specific cell signaling proteins. Although targeting Hsp90 with the antibiotic inhibitor geldanamycin (GA) may be a promising approach for cancer treatment, little is known about the determinants of Hsp90 interaction with its client proteins. Here we identify a loop within the N lobe of the kinase domain of ErbB2 that determines Hsp90 binding. The amino acid sequence of the loop determines the electrostatic and hydrophobic character of the protein's surface, which in turn govern interaction with Hsp90. A point mutation within the loop that alters ErbB2 surface properties disrupts Hsp90 association and confers GA resistance. Notably, the immature ErbB2 point mutant remains sensitive to GA, suggesting that mature and nascent client kinases may use distinct motifs to interact with the Hsp90 chaperone complex.
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Affiliation(s)
- Wanping Xu
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, Rockville, Maryland 20850, USA
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37
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Buttgereit F, Straub RH, Wehling M, Burmester GR. Glucocorticoids in the treatment of rheumatic diseases: an update on the mechanisms of action. ACTA ACUST UNITED AC 2004; 50:3408-17. [PMID: 15529366 DOI: 10.1002/art.20583] [Citation(s) in RCA: 216] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- Frank Buttgereit
- Department of Rheumatology and Clinical Immunology, Charité University Hospital, Schumannstrasse 20/21, 10117 Berlin, Germany.
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38
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Harrell JM, Murphy PJM, Morishima Y, Chen H, Mansfield JF, Galigniana MD, Pratt WB. Evidence for Glucocorticoid Receptor Transport on Microtubules by Dynein. J Biol Chem 2004; 279:54647-54. [PMID: 15485845 DOI: 10.1074/jbc.m406863200] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Rapid, ligand-dependent movement of glucocorticoid receptors (GR) from cytoplasm to the nucleus is hsp90-dependent, and much of the movement system has been defined. GR.hsp90 heterocomplexes isolated from cells contain one of several hsp90-binding immunophilins that link the complex to cytoplasmic dynein, a molecular motor that processes along microtubular tracks to the nucleus. The immunophilins link to dynein indirectly via the dynamitin component of the dynein-associated dynactin complex (Galigniana, M. D., Harrell, J. M., O'Hagen, H. M., Ljungman, M., and Pratt, W. B. (2004) J. Biol. Chem. 279, 22483-22489). Although it is known that rapid, hsp90-dependent GR movement requires intact microtubules, it has not been shown that the movement is dynein-dependent. Here, we show that overexpression of dynamitin, which blocks movement by dissociating the dynein motor from its cargo, inhibits ligand-dependent movement of the GR to the nucleus. We show that native GR.hsp90.immnunophilin complexes contain dynamitin as well as dynein and that GR heterocomplexes isolated from cytosol containing paclitaxel and GTP to stabilize microtubules also contain tubulin. The complete movement system, including the dynein motor complex and tubulin, can be assembled under cell-free conditions by incubating GR immune pellets with paclitaxel/GTP-stabilized cytosol prepared from GR(-) L cells. This is the first evidence that the movement of a steroid receptor is dynein-dependent, and it is the first isolation of a steroid receptor bound to the entire system that determines its retrograde movement.
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Affiliation(s)
- Jennifer M Harrell
- Department of Pharmacology, the University of Michigan Medical School, Ann Arbor, Michigan 48109, USA
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Billecke SS, Draganov DI, Morishima Y, Murphy PJM, Dunbar AY, Pratt WB, Osawa Y. The role of hsp90 in heme-dependent activation of apo-neuronal nitric-oxide synthase. J Biol Chem 2004; 279:30252-8. [PMID: 15155759 DOI: 10.1074/jbc.m403864200] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Like other nitric-oxide synthase (NOS) enzymes, neuronal NOS (nNOS) turnover and activity are regulated by the ubiquitous protein chaperone hsp90. We have shown previously that nNOS expressed in Sf9 cells where endogenous heme levels are low is activated from the apo- to the holo-enzyme by addition of exogenous heme to the culture medium, and this activation is inhibited by radicicol, a specific inhibitor of hsp90 (Billecke, S. S., Bender, A. T., Kanelakis, K. C., Murphy, P. J. M., Lowe, E. R., Kamada, Y., Pratt, W. B., and Osawa, Y. (2002) J. Biol. Chem. 278, 15465-15468). In this work, we examine heme binding by apo-nNOS to form the active enzyme in a cell-free system. We show that cytosol from Sf9 cells facilitates heme-dependent apo-nNOS activation by promoting functional heme insertion into the enzyme. Sf9 cytosol also converts the glucocorticoid receptor (GR) to a state where the hydrophobic ligand binding cleft is open to access by steroid. Both cell-free heme activation of purified nNOS and activation of steroid binding activity of the immunopurified GR are inhibited by radicicol treatment of Sf9 cells prior to cytosol preparation, and addition of purified hsp90 to cytosol partially overcomes this inhibition. Although there is an hsp90-dependent machinery in Sf9 cytosol that facilitates heme binding by apo-nNOS, it is clearly different from the machinery that facilitates steroid binding by the GR. hsp90 regulation of apo-nNOS heme activation is very dynamic and requires higher concentrations of radicicol for its inhibition, whereas GR steroid binding is determined by assembly of stable GR.hsp90 heterocomplexes that are formed by a purified five-chaperone machinery that does not activate apo-nNOS.
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Affiliation(s)
- Scott S Billecke
- Department of Pharmacology, The University of Michigan Medical School, Ann Arbor, Michigan 48109-0632, USA
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40
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Lan C, Lee HC, Tang S, Zhang L. A novel mode of chaperone action: heme activation of Hap1 by enhanced association of Hsp90 with the repressed Hsp70-Hap1 complex. J Biol Chem 2004; 279:27607-12. [PMID: 15102838 DOI: 10.1074/jbc.m402777200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Molecular chaperones Hsp90 and Hsp70 control many signal transducers, including cyclin-dependent kinases and steroid receptors. The yeast heme-responsive transcriptional activator Hap1 is a native substrate of both Hsp90 and Hsp70. Hsp90 and Hsp70 are critical for the precise regulation of Hap1 activity by heme. Here, to decipher the molecular events underlying the actions of Hsp90 and Hsp70 in heme regulation, we purified various multichaperone-Hap1 complexes and characterized the complexes linked to Hap1 repression and activation by two-dimensional electrophoresis analysis. Notably, we found that in vitro Hap1 is associated continuously with Ssa and its co-chaperones, and this association is not weakened by heme. Heme enhances the interaction between Hap1 and Hsp90. In vivo, defective Ssa, Ydj1, or Sro9 function causes Hap1 derepression in the absence of heme, whereas defective Hsp90 function causes reduced Hap1 activity at high heme concentrations. These results show that continuous association of Hap1 with Ssa, Ydj1, and Sro9 confers Hap1 repression, whereas enhanced association of Hsp90 with the repressed Hap1-Ssa-Ydj1-Sro9 complex by heme causes Hap1 activation. This novel mechanism of chaperone action may operate to control the activity of other important signal transducers.
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Affiliation(s)
- Changgui Lan
- Department of Environmental Health Sciences, Columbia University, Mailman School of Public Health, New York, New York 10032, USA
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41
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Morishima Y, Kanelakis KC, Murphy PJM, Lowe ER, Jenkins GJ, Osawa Y, Sunahara RK, Pratt WB. The Hsp90 Cochaperone p23 Is the Limiting Component of the Multiprotein Hsp90/Hsp70-based Chaperone System in Vivo Where It Acts to Stabilize the Client Protein·Hsp90 Complex. J Biol Chem 2003; 278:48754-63. [PMID: 14507910 DOI: 10.1074/jbc.m309814200] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A variety of signaling proteins form heterocomplexes with and are regulated by the heat shock protein chaperone hsp90. These complexes are formed by a multiprotein machinery, including hsp90 and hsp70 as essential and abundant components and Hop, hsp40, and p23 as non-essential cochaperones that are present in much lower abundance in cells. Overexpression of signaling proteins can overwhelm the capacity of this machinery to properly assemble heterocomplexes with hsp90. Here, we show that the limiting component of this assembly machinery in vitro in reticulocyte lysate and in vivo in Sf9 cells is p23. Only a fraction of glucocorticoid receptors (GR) overexpressed in Sf9 cells are in heterocomplex with hsp90 and have steroid binding activity, with the majority of the receptors present as both insoluble and cytosolic GR aggregates. Coexpression of p23 with the GR increases the proportion of cytosolic receptors that are in stable GR.hsp90 heterocomplexes with steroid binding activity, a strictly hsp90-dependent activity for the GR. Coexpression of p23 eliminates the insoluble GR aggregates and shifts the cytosolic receptor from very large aggregates without steroid binding activity to approximately 600-kDa heterocomplexes with steroid binding activity. These data lead us to conclude that p23 acts in vivo to stabilize hsp90 binding to client protein.
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Affiliation(s)
- Yoshihiro Morishima
- Department of Pharmacology, The University of Michigan Medical School, Ann Arbor, Michigan 48109, USA.
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