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Schmidt LS, Linehan WM. FLCN: The causative gene for Birt-Hogg-Dubé syndrome. Gene 2018; 640:28-42. [PMID: 28970150 PMCID: PMC5682220 DOI: 10.1016/j.gene.2017.09.044] [Citation(s) in RCA: 99] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Revised: 09/11/2017] [Accepted: 09/21/2017] [Indexed: 01/30/2023]
Abstract
Germline mutations in the novel tumor suppressor gene FLCN are responsible for the autosomal dominant inherited disorder Birt-Hogg-Dubé (BHD) syndrome that predisposes to fibrofolliculomas, lung cysts and spontaneous pneumothorax, and an increased risk for developing kidney tumors. Although the encoded protein, folliculin (FLCN), has no sequence homology to known functional domains, x-ray crystallographic studies have shown that the C-terminus of FLCN has structural similarity to DENN (differentially expressed in normal cells and neoplasia) domain proteins that act as guanine nucleotide exchange factors (GEFs) for small Rab GTPases. FLCN forms a complex with folliculin interacting proteins 1 and 2 (FNIP1, FNIP2) and with 5' AMP-activated protein kinase (AMPK). This review summarizes FLCN functional studies which support a role for FLCN in diverse metabolic pathways and cellular processes that include modulation of the mTOR pathway, regulation of PGC1α and mitochondrial biogenesis, cell-cell adhesion and RhoA signaling, control of TFE3/TFEB transcriptional activity, amino acid-dependent activation of mTORC1 on lysosomes through Rag GTPases, and regulation of autophagy. Ongoing research efforts are focused on clarifying the primary FLCN-associated pathway(s) that drives the development of fibrofolliculomas, lung cysts and kidney tumors in BHD patients carrying germline FLCN mutations.
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Affiliation(s)
- Laura S Schmidt
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, United States; Basic Science Program, Leidos Biomedical Research, Inc., Frederick Laboratory for Cancer Research, Frederick, MD 21702, United States.
| | - W Marston Linehan
- Urologic Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, United States.
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Shelton LB, Koren J, Blair LJ. Imbalances in the Hsp90 Chaperone Machinery: Implications for Tauopathies. Front Neurosci 2017; 11:724. [PMID: 29311797 PMCID: PMC5744016 DOI: 10.3389/fnins.2017.00724] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2017] [Accepted: 12/12/2017] [Indexed: 12/21/2022] Open
Abstract
The ATP-dependent 90 kDa heat shock protein, Hsp90, is a major regulator of protein triage, from assisting in nascent protein folding to refolding or degrading aberrant proteins. Tau, a microtubule associated protein, aberrantly accumulates in Alzheimer's disease (AD) and other neurodegenerative diseases, deemed tauopathies. Hsp90 binds to and regulates tau fate in coordination with a diverse group of co-chaperones. Imbalances in chaperone levels and activity, as found in the aging brain, can contribute to disease onset and progression. For example, the levels of the Hsp90 co-chaperone, FK506-binding protein 51 kDa (FKBP51), progressively increase with age. In vitro and in vivo tau models demonstrated that FKBP51 synergizes with Hsp90 to increase neurotoxic tau oligomer production. Inversely, protein phosphatase 5 (PP5), which dephosphorylates tau to restore microtubule-binding function, is repressed with aging and activity is further repressed in AD. Similarly, levels of cyclophilin 40 (CyP40) are reduced in the aged brain and further repressed in AD. Interestingly, CyP40 was shown to breakup tau aggregates in vitro and prevent tau-induced neurotoxicity in vivo. Moreover, the only known stimulator of Hsp90 ATPase activity, Aha1, increases tau aggregation and toxicity. While the levels of Aha1 are not significantly altered with aging, increased levels have been found in AD brains. Overall, these changes in the Hsp90 heterocomplex could drive tau deposition and neurotoxicity. While the relationship of tau and Hsp90 in coordination with these co-chaperones is still under investigation, it is clear that imbalances in these proteins with aging can contribute to disease onset and progression. This review highlights the current understanding of how the Hsp90 family of molecular chaperones regulates tau or other misfolded proteins in neurodegenerative diseases with a particular emphasis on the impact of aging.
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Affiliation(s)
- Lindsey B Shelton
- Department of Molecular Medicine and USF Health Byrd Institute, University of South Florida, Tampa, FL, United States
| | - John Koren
- Department of Molecular Medicine and USF Health Byrd Institute, University of South Florida, Tampa, FL, United States
| | - Laura J Blair
- Department of Molecular Medicine and USF Health Byrd Institute, University of South Florida, Tampa, FL, United States
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Weidenauer L, Wang T, Joshi S, Chiosis G, Quadroni MR. Proteomic interrogation of HSP90 and insights for medical research. Expert Rev Proteomics 2017; 14:1105-1117. [PMID: 28990809 PMCID: PMC6027630 DOI: 10.1080/14789450.2017.1389649] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
INTRODUCTION Heat shock protein 90 (HSP90) regulates protein homeostasis in eukaryotes. As a 'professional interactor', HSP90 binds to and chaperones many proteins and has both housekeeping and disease-related functions but its regulation remains in part elusive. HSP90 complexes are a target for therapy, notably against cancer, and several inhibitors are currently in clinical trials. Proteomic studies have revealed the vast interaction network of HSP90 and, in doing so, the extent of cellular processes the chaperone takes part in, especially in yeast and human cells. Furthermore, small-molecule inhibitors were used to probe the global impact of its inhibition on the proteome. Areas covered: We review here recent HSP90-related interactomics and total proteome studies and their relevance for research on cancer, neurodegenerative and pathogen diseases. Expert commentary: Proteomics experiments are our best chance to identify the context-dependent global proteome of HSP90 and thus uncover and understand its disease-specific biology. However, understanding the complexity of HSP90 will require multiple complementary, quantitative approaches and novel bioinformatics to translate interactions into ordered functional networks and pathways. Developing therapies will necessitate more knowledge on HSP90 complexes and networks with disease relevance and on total proteome changes induced by their perturbation. Most work has been done in cancer, thus a lot remains to be done in the context of other diseases.
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Affiliation(s)
- Lorenz Weidenauer
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland
| | - Tai Wang
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Suhasini Joshi
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Gabriela Chiosis
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
- Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY, USA
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Woodford MR, Sager RA, Marris E, Dunn DM, Blanden AR, Murphy RL, Rensing N, Shapiro O, Panaretou B, Prodromou C, Loh SN, Gutmann DH, Bourboulia D, Bratslavsky G, Wong M, Mollapour M. Tumor suppressor Tsc1 is a new Hsp90 co-chaperone that facilitates folding of kinase and non-kinase clients. EMBO J 2017; 36:3650-3665. [PMID: 29127155 PMCID: PMC5730846 DOI: 10.15252/embj.201796700] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 09/15/2017] [Accepted: 10/02/2017] [Indexed: 12/29/2022] Open
Abstract
The tumor suppressors Tsc1 and Tsc2 form the tuberous sclerosis complex (TSC), a regulator of mTOR activity. Tsc1 stabilizes Tsc2; however, the precise mechanism involved remains elusive. The molecular chaperone heat‐shock protein 90 (Hsp90) is an essential component of the cellular homeostatic machinery in eukaryotes. Here, we show that Tsc1 is a new co‐chaperone for Hsp90 that inhibits its ATPase activity. The C‐terminal domain of Tsc1 (998–1,164 aa) forms a homodimer and binds to both protomers of the Hsp90 middle domain. This ensures inhibition of both subunits of the Hsp90 dimer and prevents the activating co‐chaperone Aha1 from binding the middle domain of Hsp90. Conversely, phosphorylation of Aha1‐Y223 increases its affinity for Hsp90 and displaces Tsc1, thereby providing a mechanism for equilibrium between binding of these two co‐chaperones to Hsp90. Our findings establish an active role for Tsc1 as a facilitator of Hsp90‐mediated folding of kinase and non‐kinase clients—including Tsc2—thereby preventing their ubiquitination and proteasomal degradation.
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Affiliation(s)
- Mark R Woodford
- Department of Urology, SUNY Upstate Medical University, Syracuse, NY, USA.,Upstate Cancer Center, SUNY Upstate Medical University, Syracuse, NY, USA
| | - Rebecca A Sager
- Department of Urology, SUNY Upstate Medical University, Syracuse, NY, USA.,Upstate Cancer Center, SUNY Upstate Medical University, Syracuse, NY, USA.,Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, USA
| | - Elijah Marris
- Department of Urology, SUNY Upstate Medical University, Syracuse, NY, USA.,Upstate Cancer Center, SUNY Upstate Medical University, Syracuse, NY, USA.,Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, USA
| | - Diana M Dunn
- Department of Urology, SUNY Upstate Medical University, Syracuse, NY, USA.,Upstate Cancer Center, SUNY Upstate Medical University, Syracuse, NY, USA.,Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, USA
| | - Adam R Blanden
- Upstate Cancer Center, SUNY Upstate Medical University, Syracuse, NY, USA.,Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, USA
| | - Ryan L Murphy
- Department of Urology, SUNY Upstate Medical University, Syracuse, NY, USA.,Upstate Cancer Center, SUNY Upstate Medical University, Syracuse, NY, USA
| | - Nicholas Rensing
- Department of Neurology, Washington University School of Medicine, St. Louis, MO, USA.,Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO, USA
| | - Oleg Shapiro
- Department of Urology, SUNY Upstate Medical University, Syracuse, NY, USA.,Upstate Cancer Center, SUNY Upstate Medical University, Syracuse, NY, USA
| | - Barry Panaretou
- Institute of Pharmaceutical Science, King's College London, London, UK
| | | | - Stewart N Loh
- Upstate Cancer Center, SUNY Upstate Medical University, Syracuse, NY, USA.,Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, USA
| | - David H Gutmann
- Department of Neurology, Washington University School of Medicine, St. Louis, MO, USA
| | - Dimitra Bourboulia
- Department of Urology, SUNY Upstate Medical University, Syracuse, NY, USA.,Upstate Cancer Center, SUNY Upstate Medical University, Syracuse, NY, USA.,Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, USA
| | - Gennady Bratslavsky
- Department of Urology, SUNY Upstate Medical University, Syracuse, NY, USA.,Upstate Cancer Center, SUNY Upstate Medical University, Syracuse, NY, USA
| | - Michael Wong
- Department of Neurology, Washington University School of Medicine, St. Louis, MO, USA.,Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO, USA
| | - Mehdi Mollapour
- Department of Urology, SUNY Upstate Medical University, Syracuse, NY, USA .,Upstate Cancer Center, SUNY Upstate Medical University, Syracuse, NY, USA.,Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, Syracuse, NY, USA
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Sahasrabudhe P, Rohrberg J, Biebl MM, Rutz DA, Buchner J. The Plasticity of the Hsp90 Co-chaperone System. Mol Cell 2017; 67:947-961.e5. [PMID: 28890336 DOI: 10.1016/j.molcel.2017.08.004] [Citation(s) in RCA: 92] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Revised: 06/10/2017] [Accepted: 08/08/2017] [Indexed: 11/20/2022]
Abstract
The Hsp90 system in the eukaryotic cytosol is characterized by a cohort of co-chaperones that bind to Hsp90 and affect its function. Although progress has been made regarding the underlying biochemical mechanisms, how co-chaperones influence Hsp90 client proteins in vivo has remained elusive. By investigating the effect of 12 Hsp90 co-chaperones on the activity of different client proteins in yeast, we find that deletion of co-chaperones can have a neutral or negative effect on client activity but can also lead to more active clients. Only a few co-chaperones are active on all clients studied. Closely related clients and even point mutants can depend on different co-chaperones. These effects are direct because differences in client-co-chaperone interactions can be reconstituted in vitro. Interestingly, some co-chaperones affect client conformation in vivo. Thus, co-chaperones adapt the Hsp90 cycle to the requirements of the client proteins, ensuring optimal activation.
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Affiliation(s)
- Priyanka Sahasrabudhe
- Center for Integrated Protein Science at the Department of Chemistry, Technische Universität München, 85748 Garching, Germany
| | - Julia Rohrberg
- Center for Integrated Protein Science at the Department of Chemistry, Technische Universität München, 85748 Garching, Germany
| | - Maximillian M Biebl
- Center for Integrated Protein Science at the Department of Chemistry, Technische Universität München, 85748 Garching, Germany
| | - Daniel A Rutz
- Center for Integrated Protein Science at the Department of Chemistry, Technische Universität München, 85748 Garching, Germany
| | - Johannes Buchner
- Center for Integrated Protein Science at the Department of Chemistry, Technische Universität München, 85748 Garching, Germany.
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