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Mai X, Shang J, Chen Q, Gu S, Hong Y, Zhou J, Zhang M. Endophilin A2 protects against renal fibrosis by targeting TGF-β/Smad signaling. FASEB J 2022; 36:e22603. [PMID: 36259445 DOI: 10.1096/fj.202101769r] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 09/12/2022] [Accepted: 09/28/2022] [Indexed: 11/11/2022]
Abstract
Renal fibrosis underlies all forms of end-stage kidney disease. Endophilin A2 (EndoA2) plays a role in nephrotic syndrome; however, its effect on renal fibrosis remains unknown. Here, we demonstrate that EndoA2 protects against kidney interstitial fibrosis via the transforming growth factor-β (TGF-β)/Smad signaling pathway. Mouse kidneys with fibrosis or kidney biopsy specimens from patients with fibrotic nephropathy had lower levels of EndoA2 protein expression than that in kidneys without fibrosis. In vivo overexpression of EndoA2 with the endophilin A2 transgene (EndoA2Tg ) notably prevented renal fibrosis, decreased the protein expression of profibrotic molecules, suppressed tubular injury, and reduced apoptotic tubular cells in the obstructed kidney cortex of mice with unilateral ureteral obstruction (UUO). In vivo and in vitro overexpression of EndoA2 markedly inhibited UUO- or TGF-β1-induced phosphorylation of Smad2/3 and tubular epithelial cells dedifferentiation. Furthermore, EndoA2 was co-immunoprecipitated with the type II TGF-β receptor (TβRII), thus inhibiting the binding of the type I TGF-β receptor (TβRI) to TβRII. These findings indicate that EndoA2 mitigates renal fibrosis, at least partially, via modulating the TGF-β/Smad signaling. Targeting EndoA2 may be a new potential therapeutic strategy for treatment of renal fibrosis.
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Affiliation(s)
- Xiaoyi Mai
- Intensive Care Research Team of Traditional Chinese Medicine & AMI Key Lab of Chinese Medicine in Guangzhou, Guangdong Provincial Hospital of Chinese Medicine, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Jinyan Shang
- Department of Pharmacology, Cardiac and Cerebral Vascular Research Center, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| | - Qiuyuan Chen
- Department of Organ Transplantation, Guangdong Provincial Hospital of Chinese Medicine, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Shijie Gu
- Department of Organ Transplantation, Guangdong Provincial Hospital of Chinese Medicine, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Yu Hong
- Department of Pharmacology, Cardiac and Cerebral Vascular Research Center, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| | - Jiaguo Zhou
- Department of Pharmacology, Cardiac and Cerebral Vascular Research Center, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, China
| | - Minzhou Zhang
- Intensive Care Research Team of Traditional Chinese Medicine & AMI Key Lab of Chinese Medicine in Guangzhou, Guangdong Provincial Hospital of Chinese Medicine, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China.,Department of Critical Care Medicine, Guangdong Provincial Hospital of Chinese Medicine, The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
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2
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Casamento A, Boucrot E. Molecular mechanism of Fast Endophilin-Mediated Endocytosis. Biochem J 2020; 477:2327-2345. [PMID: 32589750 PMCID: PMC7319585 DOI: 10.1042/bcj20190342] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 05/11/2020] [Accepted: 05/18/2020] [Indexed: 12/13/2022]
Abstract
Endocytosis mediates the cellular uptake of micronutrients and cell surface proteins. Clathrin-mediated endocytosis (CME) is the housekeeping pathway in resting cells but additional Clathrin-independent endocytic (CIE) routes, including Fast Endophilin-Mediated Endocytosis (FEME), internalize specific cargoes and support diverse cellular functions. FEME is part of the Dynamin-dependent subgroup of CIE pathways. Here, we review our current understanding of the molecular mechanism of FEME. Key steps are: (i) priming, (ii) cargo selection, (iii) membrane curvature and carrier formation, (iv) membrane scission and (v) cytosolic transport. All steps are controlled by regulatory mechanisms mediated by phosphoinositides and by kinases such as Src, LRRK2, Cdk5 and GSK3β. A key feature of FEME is that it is not constitutively active but triggered upon the stimulation of selected cell surface receptors by their ligands. In resting cells, there is a priming cycle that concentrates Endophilin into clusters on discrete locations of the plasma membrane. In the absence of receptor activation, the patches quickly abort and new cycles are initiated nearby, constantly priming the plasma membrane for FEME. Upon activation, receptors are swiftly sorted into pre-existing Endophilin clusters, which then bud to form FEME carriers within 10 s. We summarize the hallmarks of FEME and the techniques and assays required to identify it. Next, we review similarities and differences with other CIE pathways and proposed cargoes that may use FEME to enter cells. Finally, we submit pending questions and future milestones and discuss the exciting perspectives that targeting FEME may boost treatments against cancer and neurodegenerative diseases.
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Affiliation(s)
- Alessandra Casamento
- Institute of Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BT, U.K
| | - Emmanuel Boucrot
- Institute of Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BT, U.K
- Institute of Structural and Molecular Biology, Birkbeck College, Malet Street, London WC1E 7HX, U.K
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3
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Frangež Ž, Fernández-Marrero Y, Stojkov D, Seyed Jafari SM, Hunger RE, Djonov V, Riether C, Simon HU. BIF-1 inhibits both mitochondrial and glycolytic ATP production: its downregulation promotes melanoma growth. Oncogene 2020; 39:4944-4955. [PMID: 32493957 DOI: 10.1038/s41388-020-1339-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2020] [Revised: 05/19/2020] [Accepted: 05/27/2020] [Indexed: 11/09/2022]
Abstract
Endophilin B1, also known as BAX-interacting protein 1 (BIF-1), is part of the endophilin B protein family, and is a multifunctional protein involved in the regulation of apoptosis, autophagy, and mitochondrial morphology. The role of BIF-1 in cancer is controversial since previous reports indicated to both tumor-promoting and tumor-suppressive roles, perhaps depending on the cancer cell type. In the present study, we report that BIF-1 is significantly downregulated in both primary and metastatic melanomas, and that patients with high levels of BIF-1 expression exhibited a better overall survival. Depleting BIF-1 using CRISPR/Cas9 technology in melanoma cells resulted in higher proliferation rates both in vitro and in vivo, a finding that was associated with increased ATP production, metabolic acidification, and mitochondrial respiration. We also observed mitochondrial hyperpolarization, but no increase in the mitochondrial content of BIF-1-knockout melanoma cells. In contrast, such knockout melanoma cells were equally sensitive to anticancer drug- or UV irradiation-induced cell death, and exhibited similar autophagic activities as compared with control cells. Taken together, it appears that downregulation of BIF-1 contributes to tumorigenesis in cutaneous melanoma by upregulating mitochondrial respiration and metabolism, independent of its effect on apoptosis and autophagy.
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Affiliation(s)
- Živa Frangež
- Institute of Pharmacology, University of Bern, Bern, Switzerland
| | | | - Darko Stojkov
- Institute of Pharmacology, University of Bern, Bern, Switzerland
| | - S Morteza Seyed Jafari
- Department of Dermatology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Robert E Hunger
- Department of Dermatology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | | | - Carsten Riether
- Tumor Immunology, Department for Biomedical Research, University of Bern, Bern, Switzerland.,Department of Medical Oncology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Hans-Uwe Simon
- Institute of Pharmacology, University of Bern, Bern, Switzerland. .,Department of Clinical Immunology and Allergology, Sechenov University, Moscow, Russia.
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4
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Liu CZ, Li FY, Lv XF, Ma MM, Li XY, Lin CX, Wang GL, Guan YY. Endophilin A2 regulates calcium-activated chloride channel activity via selective autophagy-mediated TMEM16A degradation. Acta Pharmacol Sin 2020; 41:208-217. [PMID: 31484993 PMCID: PMC7470808 DOI: 10.1038/s41401-019-0298-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2019] [Accepted: 08/06/2019] [Indexed: 02/05/2023] Open
Abstract
TMEM16A Ca2+-activated chloride channel (CaCC) plays an essential role in vascular homeostasis. In this study we investigated the molecular mechanisms underlying downregulation of TMEM16A CaCC activity during hypertension. In cultured basilar artery smooth muscle cells (BASMCs) isolated from 2k2c renohypertesive rats, treatment with angiotensin II (0.125-1 μM) dose-dependently increased endophilin A2 levels and decreased TMEM16A expression. Similar phenomenon was observed in basilar artery isolated from 2k2c rats. We then used whole-cell recording to examine whether endophilin A2 could regulate TMEM16A CaCC activity in BASMCs and found that knockdown of endophilin A2 significantly enhanced CaCC activity, whereas overexpression of endophilin A2 produced the opposite effect. Overexpression of endophilin A2 did not affect the TMEM16A mRNA level, but markedly decreased TMEM16A protein level in BASMCs by inducing ubiquitination and autophagy of TMEM16A. Ubiquitin-binding receptor p62 (SQSTM1) could bind to ubiquitinated TMEM16A and resulted in a process of TMEM16A proteolysis in autophagosome/lysosome. These data provide new insights into the regulation of TMEM16A CaCC activity by endophilin A2 in BASMCs, which partly explains the mechanism of angiotensin-II-induced TMEM16A inhibition during hypertension-induced vascular remodeling.
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Affiliation(s)
- Can-Zhao Liu
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China.
| | - Fei-Ya Li
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China
- Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, Toronto, ON, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
| | - Xiao-Fei Lv
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China
| | - Ming-Ming Ma
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China
| | - Xiang-Yu Li
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China
| | - Cai-Xia Lin
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China
| | - Guan-Lei Wang
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China
| | - Yong-Yuan Guan
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China.
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5
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Liu Y, Shen HJ, Wang XQY, Liu HQ, Zheng LY, Luo JD. EndophilinA2 protects against angiotensin II-induced cardiac hypertrophy by inhibiting angiotensin II type 1 receptor trafficking in neonatal rat cardiomyocytes. J Cell Biochem 2018; 119:8290-8303. [PMID: 29923351 DOI: 10.1002/jcb.26862] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Accepted: 03/13/2018] [Indexed: 01/12/2023]
Abstract
Cardiac hypertrophy is one of the major risk factors for chronic heart failure. The role of endophilinA2 (EndoA2) in clathrin-mediated endocytosis and clathrin-independent endocytosis is well documented. In the present study, we tested the hypothesis that EndoA2 protects against angiotensin II (Ang II)-induced cardiac hypertrophy by mediating intracellular angiotensin II type 1 receptor (AT1-R) trafficking in neonatal rat cardiomyocytes (NRCMs). Cardiac hypertrophy was evaluated by using cell surface area and quantitative RT-PCR (qPCR) analyses. For the first time, we found that EndoA2 attenuated cardiac hypertrophy and fibrosis induced by Ang II. Moreover, EndoA2 inhibited apoptosis induced by excessive endoplasmic reticulum stress (ERS), which accounted for the beneficial effects of EndoA2 on cardiac hypertrophy. We further revealed that there was an interaction between EndoA2 and AT1-R.The expression levels of EndoA2, which inhibits AT1-R transport from the cytoplasm to the membrane, and the interaction between EndoA2 and AT1-R were obviously decreased after Ang II treatment. Furthermore, Ang II inhibited the co-localization of AT1-R with GRP-78, which was reversed by EndoA2 overexpression. In conclusion, our results suggested that EndoA2 plays a role in protecting against cardiac hypertrophy induced by Ang II, possibly by inhibiting AT1-R transport from the cytoplasm to the membrane to suppress signal transduction.
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Affiliation(s)
- Yun Liu
- Department of Pharmacology, School of Pharmaceutical Sciences and the Fifth Affiliated Hospital, Guangzhou Medical University, Guangzhou, P.R. China.,Guangzhou Institute of Cardiovascular Disease, Guangzhou Key Laboratory of Cardiovascular Disease, and the Second Affiliated Hospital, Guangzhou Medical University, Guangzhou, P.R. China
| | - Huan-Jia Shen
- Department of Pharmacology, School of Pharmaceutical Sciences and the Fifth Affiliated Hospital, Guangzhou Medical University, Guangzhou, P.R. China
| | - Xin-Qiu-Yue Wang
- Department of Pharmacology, School of Pharmaceutical Sciences and the Fifth Affiliated Hospital, Guangzhou Medical University, Guangzhou, P.R. China
| | - Hai-Qi Liu
- Department of Pharmacology, School of Pharmaceutical Sciences and the Fifth Affiliated Hospital, Guangzhou Medical University, Guangzhou, P.R. China
| | - Ling-Yun Zheng
- School of Basic Course, Guangdong Pharmaceutical University, Guangzhou, P.R. China
| | - Jian-Dong Luo
- Guangzhou Institute of Cardiovascular Disease, Guangzhou Key Laboratory of Cardiovascular Disease, and the Second Affiliated Hospital, Guangzhou Medical University, Guangzhou, P.R. China
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6
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Liu CZ, Li XY, Du RH, Gao M, Ma MM, Li FY, Huang EW, Sun HS, Wang GL, Guan YY. Endophilin A2 Influences Volume-Regulated Chloride Current by Mediating ClC-3 Trafficking in Vascular Smooth Muscle Cells. Circ J 2016; 80:2397-2406. [DOI: 10.1253/circj.cj-16-0793] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Can-Zhao Liu
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-sen University
| | - Xiang-Yu Li
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-sen University
| | - Ren-Hong Du
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-sen University
| | - Min Gao
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-sen University
| | - Ming-Ming Ma
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-sen University
| | - Fei-Ya Li
- Departments of Surgery and Physiology, Institute of Medical Science, Faculty of Medicine, University of Toronto
| | - Er-Wen Huang
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-sen University
| | - Hong-Shuo Sun
- Departments of Surgery and Physiology, Institute of Medical Science, Faculty of Medicine, University of Toronto
| | - Guan-Lei Wang
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-sen University
| | - Yong-Yuan Guan
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-sen University
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7
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Wuertenberger S, Groemping Y. A single PXXP motif in the C-terminal region of srGAP3 mediates binding to multiple SH3 domains. FEBS Lett 2015; 589:1156-63. [PMID: 25819436 DOI: 10.1016/j.febslet.2015.03.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Revised: 03/18/2015] [Accepted: 03/18/2015] [Indexed: 11/17/2022]
Abstract
The Slit-Robo GTPase-activating protein 3 (srGAP3) has been implicated in different critical aspects of neuronal development. These findings have mainly been based on the characterisation of the three conserved globular N-terminal domains, while the function of the C-terminal region (CTR) is still unknown. We show that this predicted unstructured region acts as an adaptor by binding to the endocytic proteins Amphiphysin, Endophilin-A2, Endophilin-A1, as well as the Ras signalling protein Grb2. All these interactions depend on a single proline-rich motif in the CTR and the Src-homology 3 domains of the binding partners. Via these interactions srGAP3 could link receptor signalling events to the endocytic machinery.
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Affiliation(s)
- Silvia Wuertenberger
- Max Planck Institute for Developmental Biology, Department of Protein Evolution, Spemannstr. 35, D-72076 Tübingen, Germany
| | - Yvonne Groemping
- Max Planck Institute for Developmental Biology, Department of Protein Evolution, Spemannstr. 35, D-72076 Tübingen, Germany.
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8
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Vannier C, Pesty A, San-Roman MJ, Schmidt AA. The Bin/amphiphysin/Rvs (BAR) domain protein endophilin B2 interacts with plectin and controls perinuclear cytoskeletal architecture. J Biol Chem 2013; 288:27619-27637. [PMID: 23921385 DOI: 10.1074/jbc.m113.485482] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Proteins of the Bin/amphiphysin/Rvs (BAR) domain superfamily are essential in controlling the shape and dynamics of intracellular membranes. Here, we present evidence for the unconventional function of a member of the endophilin family of BAR and Src homology 3 domain-containing proteins, namely endophilin B2, in the perinuclear organization of intermediate filaments. Using mass spectrometry analysis based on capturing endophilin B2 partners in in situ pre-established complexes in cells, we unravel the interaction of endophilin B2 with plectin 1, a variant of the cytoskeleton linker protein plectin as well as with vimentin. Endophilin B2 directly binds the N-terminal region of plectin 1 via Src homology 3-mediated interaction and vimentin indirectly via plectin-mediated interaction. The relevance of these interactions is strengthened by the selective and drastic reorganization of vimentin around nuclei upon overexpression of endophilin B2 and by the extensive colocalization of both proteins in a meshwork of perinuclear filamentous structures. By generating mutants of the endophilin B2 BAR domain, we show that this phenotype requires the BAR-mediated membrane binding activity of endophilin B2. Plectin 1 or endophilin B2 knockdown using RNA interference disturbed the perinuclear organization of vimentin. Altogether, these data suggest that the endophilin B2-plectin 1 complex functions as a membrane-anchoring device organizing and stabilizing the perinuclear network of vimentin filaments. Finally, we present evidence for the involvement of endophilin B2 and plectin 1 in nuclear positioning in individual cells. This points to the potential importance of the endophilin B2-plectin complex in the biological functions depending on nuclear migration and positioning.
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Affiliation(s)
- Christian Vannier
- From CNRS, UMR7592, Institut Jacques Monod, Université Paris Diderot, Sorbonne Paris Cité, 15 Rue Hélène Brion, F-75205 Paris Cedex 13, France
| | - Arlette Pesty
- From CNRS, UMR7592, Institut Jacques Monod, Université Paris Diderot, Sorbonne Paris Cité, 15 Rue Hélène Brion, F-75205 Paris Cedex 13, France
| | - Mabel Jouve San-Roman
- From CNRS, UMR7592, Institut Jacques Monod, Université Paris Diderot, Sorbonne Paris Cité, 15 Rue Hélène Brion, F-75205 Paris Cedex 13, France
| | - Anne A Schmidt
- From CNRS, UMR7592, Institut Jacques Monod, Université Paris Diderot, Sorbonne Paris Cité, 15 Rue Hélène Brion, F-75205 Paris Cedex 13, France.
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9
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Gortat A, San-Roman MJ, Vannier C, Schmidt AA. Single point mutation in Bin/Amphiphysin/Rvs (BAR) sequence of endophilin impairs dimerization, membrane shaping, and Src homology 3 domain-mediated partnership. J Biol Chem 2011; 287:4232-47. [PMID: 22167186 DOI: 10.1074/jbc.m111.325837] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Bin/Amphiphysin/Rvs (BAR) domain-containing proteins are essential players in the dynamics of intracellular compartments. The BAR domain is an evolutionarily conserved dimeric module characterized by a crescent-shaped structure whose intrinsic curvature, flexibility, and ability to assemble into highly ordered oligomers contribute to inducing the curvature of target membranes. Endophilins, diverging into A and B subgroups, are BAR and SH3 domain-containing proteins. They exert activities in membrane dynamic processes such as endocytosis, autophagy, mitochondrial dynamics, and permeabilization during apoptosis. Here, we report on the involvement of the third α-helix of the endophilin A BAR sequence in dimerization and identify leucine 215 as a key residue within a network of hydrophobic interactions stabilizing the entire BAR dimer interface. With the combination of N-terminal truncation retaining the high dimerization capacity of the third α-helices of endophilin A and leucine 215 substitution by aspartate (L215D), we demonstrate the essential role of BAR sequence-mediated dimerization on SH3 domain partnership. In comparison with wild type, full-length endophilin A2 heterodimers with one protomer bearing the L215D substitution exhibit very significant changes in membrane binding and shaping activities as well as a dramatic decrease of SH3 domain partnership. This suggests that subtle changes in the conformation and/or rigidity of the BAR domain impact both the control of membrane curvature and downstream binding to effectors. Finally, we show that expression, in mammalian cells, of endophilin A2 bearing the L215D substitution impairs the endocytic recycling of transferrin receptors.
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Affiliation(s)
- Anna Gortat
- CNRS, UMR7592, Institut Jacques Monod, Université Paris Diderot, Sorbonne Paris Cité, F-75205 Paris, France
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11
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Goetz R, Dover K, Laezza F, Shtraizent N, Huang X, Tchetchik D, Eliseenkova AV, Xu CF, Neubert TA, Ornitz DM, Goldfarb M, Mohammadi M. Crystal structure of a fibroblast growth factor homologous factor (FHF) defines a conserved surface on FHFs for binding and modulation of voltage-gated sodium channels. J Biol Chem 2009; 284:17883-96. [PMID: 19406745 DOI: 10.1074/jbc.m109.001842] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Voltage-gated sodium channels (Nav) produce sodium currents that underlie the initiation and propagation of action potentials in nerve and muscle cells. Fibroblast growth factor homologous factors (FHFs) bind to the intracellular C-terminal region of the Nav alpha subunit to modulate fast inactivation of the channel. In this study we solved the crystal structure of a 149-residue-long fragment of human FHF2A which unveils the structural features of the homology core domain of all 10 human FHF isoforms. Through analysis of crystal packing contacts and site-directed mutagenesis experiments we identified a conserved surface on the FHF core domain that mediates channel binding in vitro and in vivo. Mutations at this channel binding surface impaired the ability of FHFs to co-localize with Navs at the axon initial segment of hippocampal neurons. The mutations also disabled FHF modulation of voltage-dependent fast inactivation of sodium channels in neuronal cells. Based on our data, we propose that FHFs constitute auxiliary subunits for Navs.
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Affiliation(s)
- Regina Goetz
- Department of Pharmacology, Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY 10016, USA
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