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Cai H, Li X, Niu X, Li J, Lan X, Lei C, Huang Y, Xu H, Li M, Chen H. Copy number variations within fibroblast growth factor 13 gene influence growth traits and alternative splicing in cattle. Anim Biotechnol 2024; 35:2314104. [PMID: 38426908 DOI: 10.1080/10495398.2024.2314104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/02/2024]
Abstract
Previous researches revealed a copy number variation (CNV) region in the bovine fibroblast growth factor 13 (FGF13) gene. However, its effects remain unknown. This study detected the various copy number types in seven Chinese cattle breeds and analysed their population genetic characteristics and effects on growth traits and transcription levels. Copy number Loss was more frequent in Caoyuan Red cattle and Xianan cattle than in the other breeds. Association analysis between CNV and growth traits of Qinchuan indicated that the CNV was significantly related to chest depth, hip width and hucklebone width (P < 0.05). Additionally, the growth traits of individuals with copy number Loss were significantly inferior to those with copy number Gain or Median (P < 0.05). Besides, we found two splicing isoforms, AS1 and AS2, in FGF13 gene, which resulted from alternative 5' splicing sites of intron 1. These isoforms showed varied expression levels in various tissues. Moreover, CNV was significantly and negatively associated with the mRNA expression of AS1 (r = -0.525, P < 0.05). The CNVs in bovine FGF13 gene negatively regulated growth traits and gene transcription. These observations provide new insights into bovine FGF13 gene, delivering potentially useful information for future Chinese cattle breeding programs.
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Affiliation(s)
- Hanfang Cai
- College of Animal Science and Technology, Henan Agriculture University, Zhengzhou, China
| | - Xin Li
- College of Animal Science and Technology, Henan Agriculture University, Zhengzhou, China
| | - Xinran Niu
- College of Animal Science and Technology, Henan Agriculture University, Zhengzhou, China
| | - Jing Li
- Animal Health Supervision Institute of Biyang, Biyang, Henan, China
| | - Xianyong Lan
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China
| | - Chuzhao Lei
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China
| | - Yongzhen Huang
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Shaanxi Province, College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China
| | - Huifen Xu
- College of Animal Science and Technology, Henan Agriculture University, Zhengzhou, China
| | - Ming Li
- College of Animal Science and Technology, Henan Agriculture University, Zhengzhou, China
| | - Hong Chen
- College of Animal Science, Xinjiang Agriculture University, Urumqi, China
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Libé-Philippot B, Lejeune A, Wierda K, Louros N, Erkol E, Vlaeminck I, Beckers S, Gaspariunaite V, Bilheu A, Konstantoulea K, Nyitrai H, De Vleeschouwer M, Vennekens KM, Vidal N, Bird TW, Soto DC, Jaspers T, Dewilde M, Dennis MY, Rousseau F, Comoletti D, Schymkowitz J, Theys T, de Wit J, Vanderhaeghen P. LRRC37B is a human modifier of voltage-gated sodium channels and axon excitability in cortical neurons. Cell 2023; 186:5766-5783.e25. [PMID: 38134874 PMCID: PMC10754148 DOI: 10.1016/j.cell.2023.11.028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 06/28/2023] [Accepted: 11/27/2023] [Indexed: 12/24/2023]
Abstract
The enhanced cognitive abilities characterizing the human species result from specialized features of neurons and circuits. Here, we report that the hominid-specific gene LRRC37B encodes a receptor expressed in human cortical pyramidal neurons (CPNs) and selectively localized to the axon initial segment (AIS), the subcellular compartment triggering action potentials. Ectopic expression of LRRC37B in mouse CPNs in vivo leads to reduced intrinsic excitability, a distinctive feature of some classes of human CPNs. Molecularly, LRRC37B binds to the secreted ligand FGF13A and to the voltage-gated sodium channel (Nav) β-subunit SCN1B. LRRC37B concentrates inhibitory effects of FGF13A on Nav channel function, thereby reducing excitability, specifically at the AIS level. Electrophysiological recordings in adult human cortical slices reveal lower neuronal excitability in human CPNs expressing LRRC37B. LRRC37B thus acts as a species-specific modifier of human neuron excitability, linking human genome and cell evolution, with important implications for human brain function and diseases.
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Affiliation(s)
- Baptiste Libé-Philippot
- VIB-KU Leuven Center for Brain & Disease Research, 3000 Leuven, Belgium; KUL, Department of Neurosciences, Leuven Brain Institute, 3000 Leuven, Belgium
| | - Amélie Lejeune
- VIB-KU Leuven Center for Brain & Disease Research, 3000 Leuven, Belgium; KUL, Department of Neurosciences, Leuven Brain Institute, 3000 Leuven, Belgium
| | - Keimpe Wierda
- VIB-KU Leuven Center for Brain & Disease Research, 3000 Leuven, Belgium; Electrophysiology Unit, VIB-KU Leuven Center for Brain & Disease Research, 3000 Leuven, Belgium
| | - Nikolaos Louros
- VIB-KU Leuven Center for Brain & Disease Research, 3000 Leuven, Belgium; Department of Cellular and Molecular Medicine, KUL, 3000 Leuven, Belgium
| | - Emir Erkol
- VIB-KU Leuven Center for Brain & Disease Research, 3000 Leuven, Belgium; KUL, Department of Neurosciences, Leuven Brain Institute, 3000 Leuven, Belgium
| | - Ine Vlaeminck
- VIB-KU Leuven Center for Brain & Disease Research, 3000 Leuven, Belgium; Electrophysiology Unit, VIB-KU Leuven Center for Brain & Disease Research, 3000 Leuven, Belgium
| | - Sofie Beckers
- VIB-KU Leuven Center for Brain & Disease Research, 3000 Leuven, Belgium; KUL, Department of Neurosciences, Leuven Brain Institute, 3000 Leuven, Belgium
| | - Vaiva Gaspariunaite
- VIB-KU Leuven Center for Brain & Disease Research, 3000 Leuven, Belgium; KUL, Department of Neurosciences, Leuven Brain Institute, 3000 Leuven, Belgium
| | - Angéline Bilheu
- Université Libre de Bruxelles (ULB), Institute for Interdisciplinary Research (IRIBHM), 1070 Brussels, Belgium
| | - Katerina Konstantoulea
- VIB-KU Leuven Center for Brain & Disease Research, 3000 Leuven, Belgium; Department of Cellular and Molecular Medicine, KUL, 3000 Leuven, Belgium
| | - Hajnalka Nyitrai
- VIB-KU Leuven Center for Brain & Disease Research, 3000 Leuven, Belgium; KUL, Department of Neurosciences, Leuven Brain Institute, 3000 Leuven, Belgium
| | - Matthias De Vleeschouwer
- VIB-KU Leuven Center for Brain & Disease Research, 3000 Leuven, Belgium; Department of Cellular and Molecular Medicine, KUL, 3000 Leuven, Belgium
| | - Kristel M Vennekens
- VIB-KU Leuven Center for Brain & Disease Research, 3000 Leuven, Belgium; KUL, Department of Neurosciences, Leuven Brain Institute, 3000 Leuven, Belgium
| | - Niels Vidal
- VIB-KU Leuven Center for Brain & Disease Research, 3000 Leuven, Belgium; KUL, Department of Neurosciences, Leuven Brain Institute, 3000 Leuven, Belgium
| | - Thomas W Bird
- School of Biological Sciences, Victoria University of Wellington, Wellington 6012, New Zealand
| | - Daniela C Soto
- Genome Center, MIND Institute, and Department of Biochemistry & Molecular Medicine, University of California, Davis, Davis, CA 95616, USA
| | - Tom Jaspers
- Laboratory for Therapeutic and Diagnostic Antibodies, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, 3000 Leuven, Belgium
| | - Maarten Dewilde
- Laboratory for Therapeutic and Diagnostic Antibodies, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, 3000 Leuven, Belgium
| | - Megan Y Dennis
- Genome Center, MIND Institute, and Department of Biochemistry & Molecular Medicine, University of California, Davis, Davis, CA 95616, USA
| | - Frederic Rousseau
- VIB-KU Leuven Center for Brain & Disease Research, 3000 Leuven, Belgium; Department of Cellular and Molecular Medicine, KUL, 3000 Leuven, Belgium
| | - Davide Comoletti
- School of Biological Sciences, Victoria University of Wellington, Wellington 6012, New Zealand; Child Health Institute of New Jersey, Rutgers University, New Brunswick, NJ 08901, USA
| | - Joost Schymkowitz
- VIB-KU Leuven Center for Brain & Disease Research, 3000 Leuven, Belgium; Department of Cellular and Molecular Medicine, KUL, 3000 Leuven, Belgium
| | - Tom Theys
- KUL, Department of Neurosciences, Leuven Brain Institute, 3000 Leuven, Belgium; Research Group Experimental Neurosurgery and Neuroanatomy, KUL, 3000 Leuven, Belgium
| | - Joris de Wit
- VIB-KU Leuven Center for Brain & Disease Research, 3000 Leuven, Belgium; KUL, Department of Neurosciences, Leuven Brain Institute, 3000 Leuven, Belgium.
| | - Pierre Vanderhaeghen
- VIB-KU Leuven Center for Brain & Disease Research, 3000 Leuven, Belgium; KUL, Department of Neurosciences, Leuven Brain Institute, 3000 Leuven, Belgium; Université Libre de Bruxelles (ULB), Institute for Interdisciplinary Research (IRIBHM), 1070 Brussels, Belgium.
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3
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Lesage A, Lorenzini M, Burel S, Sarlandie M, Bibault F, Lindskog C, Maloney D, Silva JR, Townsend RR, Nerbonne JM, Marionneau C. Determinants of iFGF13-mediated regulation of myocardial voltage-gated sodium (NaV) channels in mouse. J Gen Physiol 2023; 155:e202213293. [PMID: 37516919 PMCID: PMC10374952 DOI: 10.1085/jgp.202213293] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 03/14/2023] [Accepted: 06/30/2023] [Indexed: 07/31/2023] Open
Abstract
Posttranslational regulation of cardiac NaV1.5 channels is critical in modulating channel expression and function, yet their regulation by phosphorylation of accessory proteins has gone largely unexplored. Using phosphoproteomic analysis of NaV channel complexes from adult mouse left ventricles, we identified nine phosphorylation sites on intracellular fibroblast growth factor 13 (iFGF13). To explore the potential roles of these phosphosites in regulating cardiac NaV currents, we abolished expression of iFGF13 in neonatal and adult mouse ventricular myocytes and rescued it with wild-type (WT), phosphosilent, or phosphomimetic iFGF13-VY. While the increased rate of closed-state inactivation of NaV channels induced by Fgf13 knockout in adult cardiomyocytes was completely restored by adenoviral-mediated expression of WT iFGF13-VY, only partial rescue was observed in neonatal cardiomyocytes after knockdown. The knockdown of iFGF13 in neonatal ventricular myocytes also shifted the voltage dependence of channel activation toward hyperpolarized potentials, a shift that was not reversed by WT iFGF13-VY expression. Additionally, we found that iFGF13-VY is the predominant isoform in adult ventricular myocytes, whereas both iFGF13-VY and iFGF13-S are expressed comparably in neonatal ventricular myocytes. Similar to WT iFGF13-VY, each of the iFGF13-VY phosphomutants studied restored NaV channel inactivation properties in both models. Lastly, Fgf13 knockout also increased the late Na+ current in adult cardiomyocytes, and this effect was restored with expression of WT and phosphosilent iFGF13-VY. Together, our results demonstrate that iFGF13 is highly phosphorylated and displays differential isoform expression in neonatal and adult ventricular myocytes. While we found no roles for iFGF13 phosphorylation, our results demonstrate differential effects of iFGF13 on neonatal and adult mouse ventricular NaV channels.
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Affiliation(s)
- Adrien Lesage
- CNRS, INSERM, L’institut du Thorax, Nantes Université, Nantes, France
| | - Maxime Lorenzini
- CNRS, INSERM, L’institut du Thorax, Nantes Université, Nantes, France
| | - Sophie Burel
- CNRS, INSERM, L’institut du Thorax, Nantes Université, Nantes, France
| | - Marine Sarlandie
- CNRS, INSERM, L’institut du Thorax, Nantes Université, Nantes, France
| | - Floriane Bibault
- CNRS, INSERM, L’institut du Thorax, Nantes Université, Nantes, France
| | - Cecilia Lindskog
- Department of Immunology, Genetics and Pathology, Cancer Precision Medicine, Uppsala University, Uppsala, Sweden
| | | | - Jonathan R. Silva
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, USA
| | - R. Reid Townsend
- Department of Cell Biology and Physiology, Washington University Medical School, St. Louis, MO, USA
- Department of Medicine, Washington University Medical School, St. Louis, MO, USA
| | - Jeanne M. Nerbonne
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, USA
- Department of Medicine, Washington University Medical School, St. Louis, MO, USA
- Department of Developmental Biology, Washington University Medical School, St. Louis, MO, USA
| | - Céline Marionneau
- CNRS, INSERM, L’institut du Thorax, Nantes Université, Nantes, France
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4
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Martin KE, Ravisankar P, Beerens M, MacRae CA, Waxman JS. Nr2f1a maintains atrial nkx2.5 expression to repress pacemaker identity within venous atrial cardiomyocytes of zebrafish. eLife 2023; 12:e77408. [PMID: 37184369 PMCID: PMC10185342 DOI: 10.7554/elife.77408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Accepted: 04/28/2023] [Indexed: 05/16/2023] Open
Abstract
Maintenance of cardiomyocyte identity is vital for normal heart development and function. However, our understanding of cardiomyocyte plasticity remains incomplete. Here, we show that sustained expression of the zebrafish transcription factor Nr2f1a prevents the progressive acquisition of ventricular cardiomyocyte (VC) and pacemaker cardiomyocyte (PC) identities within distinct regions of the atrium. Transcriptomic analysis of flow-sorted atrial cardiomyocytes (ACs) from nr2f1a mutant zebrafish embryos showed increased VC marker gene expression and altered expression of core PC regulatory genes, including decreased expression of nkx2.5, a critical repressor of PC differentiation. At the arterial (outflow) pole of the atrium in nr2f1a mutants, cardiomyocytes resolve to VC identity within the expanded atrioventricular canal. However, at the venous (inflow) pole of the atrium, there is a progressive wave of AC transdifferentiation into PCs across the atrium toward the arterial pole. Restoring Nkx2.5 is sufficient to repress PC marker identity in nr2f1a mutant atria and analysis of chromatin accessibility identified an Nr2f1a-dependent nkx2.5 enhancer expressed in the atrial myocardium directly adjacent to PCs. CRISPR/Cas9-mediated deletion of the putative nkx2.5 enhancer leads to a loss of Nkx2.5-expressing ACs and expansion of a PC reporter, supporting that Nr2f1a limits PC differentiation within venous ACs via maintaining nkx2.5 expression. The Nr2f-dependent maintenance of AC identity within discrete atrial compartments may provide insights into the molecular etiology of concurrent structural congenital heart defects and associated arrhythmias.
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Affiliation(s)
- Kendall E Martin
- Molecular Genetics, Biochemistry, and Microbiology Graduate Program, University of Cincinnati College of MedicineCincinnatiUnited States
- Molecular Cardiovascular Biology Division and Heart Institute, Cincinnati Children’s Hospital Medical CenterCincinnatiUnited States
| | - Padmapriyadarshini Ravisankar
- Molecular Cardiovascular Biology Division and Heart Institute, Cincinnati Children’s Hospital Medical CenterCincinnatiUnited States
| | - Manu Beerens
- Divisions of Cardiovascular Medicine, Genetics and Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical SchoolBostonUnited States
| | - Calum A MacRae
- Divisions of Cardiovascular Medicine, Genetics and Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical SchoolBostonUnited States
| | - Joshua S Waxman
- Molecular Cardiovascular Biology Division and Heart Institute, Cincinnati Children’s Hospital Medical CenterCincinnatiUnited States
- Department of Pediatrics, University of Cincinnati College of MedicineCincinnatiUnited States
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5
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Angsutararux P, Dutta AK, Marras M, Abella C, Mellor RL, Shi J, Nerbonne JM, Silva JR. Differential regulation of cardiac sodium channels by intracellular fibroblast growth factors. J Gen Physiol 2023; 155:e202213300. [PMID: 36944081 PMCID: PMC10038838 DOI: 10.1085/jgp.202213300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 01/17/2023] [Accepted: 02/09/2023] [Indexed: 03/23/2023] Open
Abstract
Voltage-gated sodium (NaV) channels are responsible for the initiation and propagation of action potentials. In the heart, the predominant NaV1.5 α subunit is composed of four homologous repeats (I-IV) and forms a macromolecular complex with multiple accessory proteins, including intracellular fibroblast growth factors (iFGF). In spite of high homology, each of the iFGFs, iFGF11-iFGF14, as well as the individual iFGF splice variants, differentially regulates NaV channel gating, and the mechanisms underlying these differential effects remain elusive. Much of the work exploring iFGF regulation of NaV1.5 has been performed in mouse and rat ventricular myocytes in which iFGF13VY is the predominant iFGF expressed, whereas investigation into NaV1.5 regulation by the human heart-dominant iFGF12B is lacking. In this study, we used a mouse model with cardiac-specific Fgf13 deletion to study the consequences of iFGF13VY and iFGF12B expression. We observed distinct effects on the voltage-dependences of activation and inactivation of the sodium currents (INa), as well as on the kinetics of peak INa decay. Results in native myocytes were recapitulated with human NaV1.5 heterologously expressed in Xenopus oocytes, and additional experiments using voltage-clamp fluorometry (VCF) revealed iFGF-specific effects on the activation of the NaV1.5 voltage sensor domain in repeat IV (VSD-IV). iFGF chimeras further unveiled roles for all three iFGF domains (i.e., the N-terminus, core, and C-terminus) on the regulation of VSD-IV, and a slower time domain of inactivation. We present here a novel mechanism of iFGF regulation that is specific to individual iFGF isoforms and that leads to distinct functional effects on NaV channel/current kinetics.
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Affiliation(s)
- Paweorn Angsutararux
- Department of Biomedical Engineering, McKelvey School of Engineering, Washington University in St. Louis, St. Louis, MO, USA
| | - Amal K. Dutta
- Department of Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, MO, USA
| | - Martina Marras
- Department of Biomedical Engineering, McKelvey School of Engineering, Washington University in St. Louis, St. Louis, MO, USA
| | - Carlota Abella
- Department of Biomedical Engineering, McKelvey School of Engineering, Washington University in St. Louis, St. Louis, MO, USA
| | - Rebecca L. Mellor
- Department of Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, MO, USA
| | - Jingyi Shi
- Department of Biomedical Engineering, McKelvey School of Engineering, Washington University in St. Louis, St. Louis, MO, USA
| | - Jeanne M. Nerbonne
- Department of Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, MO, USA
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO, USA
| | - Jonathan R. Silva
- Department of Biomedical Engineering, McKelvey School of Engineering, Washington University in St. Louis, St. Louis, MO, USA
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6
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Lesage A, Lorenzini M, Burel S, Sarlandie M, Bibault F, Maloney D, Silva JR, Reid Townsend R, Nerbonne JM, Marionneau C. FHF2 phosphorylation and regulation of native myocardial Na V 1.5 channels. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.31.526475. [PMID: 36778222 PMCID: PMC9915605 DOI: 10.1101/2023.01.31.526475] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Phosphorylation of the cardiac Na V 1.5 channel pore-forming subunit is extensive and critical in modulating channel expression and function, yet the regulation of Na V 1.5 by phosphorylation of its accessory proteins remains elusive. Using a phosphoproteomic analysis of Na V channel complexes purified from mouse left ventricles, we identified nine phosphorylation sites on Fibroblast growth factor Homologous Factor 2 (FHF2). To determine the roles of phosphosites in regulating Na V 1.5, we developed two models from neonatal and adult mouse ventricular cardiomyocytes in which FHF2 expression is knockdown and rescued by WT, phosphosilent or phosphomimetic FHF2-VY. While the increased rates of closed-state and open-state inactivation of Na V channels induced by the FHF2 knockdown are completely restored by the FHF2-VY isoform in adult cardiomyocytes, sole a partial rescue is obtained in neonatal cardiomyocytes. The FHF2 knockdown also shifts the voltage-dependence of activation towards hyperpolarized potentials in neonatal cardiomyocytes, which is not rescued by FHF2-VY. Parallel investigations showed that the FHF2-VY isoform is predominant in adult cardiomyocytes, while expression of FHF2-VY and FHF2-A is comparable in neonatal cardiomyocytes. Similar to WT FHF2-VY, however, each FHF2-VY phosphomutant restores the Na V channel inactivation properties in both models, preventing identification of FHF2 phosphosite roles. FHF2 knockdown also increases the late Na + current in adult cardiomyocytes, which is restored similarly by WT and phosphosilent FHF2-VY. Together, our results demonstrate that ventricular FHF2 is highly phosphorylated, implicate differential roles for FHF2 in regulating neonatal and adult mouse ventricular Na V 1.5, and suggest that the regulation of Na V 1.5 by FHF2 phosphorylation is highly complex. eTOC Summary Lesage et al . identify the phosphorylation sites of FHF2 from mouse left ventricular Na V 1.5 channel complexes. While no roles for FHF2 phosphosites could be recognized yet, the findings demonstrate differential FHF2-dependent regulation of neonatal and adult mouse ventricular Na V 1.5 channels.
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Effraim PR, Estacion M, Zhao P, Sosniak D, Waxman SG, Dib-Hajj SD. Fibroblast growth factor homologous factor 2 attenuates excitability of DRG neurons. J Neurophysiol 2022; 128:1258-1266. [PMID: 36222860 PMCID: PMC9909838 DOI: 10.1152/jn.00361.2022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Fibroblast growth factor homologous factors (FHFs) are cytosolic members of the superfamily of the FGF proteins. Four members of this subfamily (FHF1-4) are differentially expressed in multiple tissues in an isoform-dependent manner. Mutations in FHF proteins have been associated with multiple neurological disorders. FHF proteins bind to the COOH terminus of voltage-gated sodium (Nav) channels and regulate current amplitude and gating properties of these channels. FHF2, which is expressed in dorsal root ganglia (DRG) neurons, has two main splicing isoforms: FHF2A and FHF2B, which differ in the length and sequence of their NH2 termini, have been shown to differentially regulate gating properties of Nav1.7, a channel that is a major driver of DRG neuron firing. FHF2 expression levels are downregulated after peripheral nerve axotomy, which suggests that they may regulate neuronal excitability via an action on Nav channels after injury. We have previously shown that knockdown of FHF2 leads to gain-of-function changes in Nav1.7 gating properties: enhanced repriming, increased current density, and hyperpolarized activation. From this we posited that knockdown of FHF2 might also lead to DRG hyperexcitability. Here we show that knockdown of either FHF2A alone or all isoforms of FHF2 results in increased DRG neuron excitability. In addition, we demonstrate that supplementation of FHF2A and FHF2B reduces DRG neuron excitability. Overexpression of FHF2A or FHF2B also reduced excitability of DRG neurons treated with a cocktail of inflammatory mediators, a model of inflammatory pain. Our data suggest that increased neuronal excitability after nerve injury might be triggered, in part, via a loss of FHF2-Nav1.7 interaction.NEW & NOTEWORTHY FHF2 is known to bind to and modulate the function of Nav1.7. FHF2 expression is also reduced after nerve injury. We demonstrate that knockdown of FHF2 expression increases DRG neuronal excitability. More importantly, overexpression of FHF2 reduces DRG excitability in basal conditions and in the presence of inflammatory mediators (a model of inflammatory pain). These results suggest that FHF2 could potentially be used as a tool to reduce DRG neuronal excitability and to treat pain.
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Affiliation(s)
- Philip R. Effraim
- Department of Anesthesiology, Yale University School of Medicine, New Haven, CT 06510
- Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06510, USA
- Center for Rehabilitation Research, VA Connecticut Healthcare System, West Haven, CT 06516, USA
| | - Mark Estacion
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06510
- Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06510, USA
- Center for Rehabilitation Research, VA Connecticut Healthcare System, West Haven, CT 06516, USA
| | - Peng Zhao
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06510
- Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06510, USA
- Center for Rehabilitation Research, VA Connecticut Healthcare System, West Haven, CT 06516, USA
| | - Daniel Sosniak
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06510
- Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06510, USA
- Center for Rehabilitation Research, VA Connecticut Healthcare System, West Haven, CT 06516, USA
| | - Stephen G Waxman
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06510
- Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06510, USA
- Center for Rehabilitation Research, VA Connecticut Healthcare System, West Haven, CT 06516, USA
| | - Sulayman D. Dib-Hajj
- Department of Neurology, Yale University School of Medicine, New Haven, CT 06510
- Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT 06510, USA
- Center for Rehabilitation Research, VA Connecticut Healthcare System, West Haven, CT 06516, USA
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Modulating effects of FGF12 variants on Na V1.2 and Na V1.6 being associated with developmental and epileptic encephalopathy and Autism spectrum disorder: A case series. EBioMedicine 2022; 83:104234. [PMID: 36029553 PMCID: PMC9429545 DOI: 10.1016/j.ebiom.2022.104234] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Revised: 08/05/2022] [Accepted: 08/05/2022] [Indexed: 01/18/2023] Open
Abstract
OBJECTIVE Fibroblast Growth Factor 12 (FGF12) may represent an important modulator of neuronal network activity and has been associated with developmental and epileptic encephalopathy (DEE). We sought to identify the underlying pathomechanism of FGF12-related disorders. METHODS Patients with pathogenic variants in FGF12 were identified through published case reports, GeneMatcher and whole exome sequencing of own case collections. The functional consequences of two missense and two copy number variants (CNVs) were studied by co-expression of wildtype and mutant FGF12 in neuronal-like cells (ND7/23) with the sodium channels NaV1.2 or NaV1.6, including their beta-1 and beta-2 sodium channel subunits (SCN1B and SCN2B). RESULTS Four variants in FGF12 were identified for functional analysis: one novel FGF12 variant in a patient with autism spectrum disorder and three variants from previously published patients affected by DEE. We demonstrate the differential regulating effects of wildtype and mutant FGF12 on NaV1.2 and NaV1.6 channels. Here, FGF12 variants lead to a complex kinetic influence on NaV1.2 and NaV1.6, including loss- as well as gain-of function changes in fast and slow inactivation. INTERPRETATION We could demonstrate the detailed regulating effect of FGF12 on NaV1.2 and NaV1.6 and confirmed the complex effect of FGF12 on neuronal network activity. Our findings expand the phenotypic spectrum related to FGF12 variants and elucidate the underlying pathomechanism. Specific variants in FGF12-associated disorders may be amenable to precision treatment with sodium channel blockers. FUNDING DFG, BMBF, Hartwell Foundation, National Institute for Neurological Disorders and Stroke, IDDRC, ENGIN, NIH, ITMAT, ILAE, RES and GRIN.
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Xiao Y, Theile JW, Zybura A, Pan Y, Lin Z, Cummins TR. A-type FHFs mediate resurgent currents through TTX-resistant voltage-gated sodium channels. eLife 2022; 11:77558. [PMID: 35441593 PMCID: PMC9071269 DOI: 10.7554/elife.77558] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Accepted: 04/19/2022] [Indexed: 11/13/2022] Open
Abstract
Resurgent currents (INaR) produced by voltage-gated sodium channels are required for many neurons to maintain high-frequency firing, and contribute to neuronal hyperexcitability and disease pathophysiology. Here we show, for the first time, that INaR can be reconstituted in a heterologous system by co-expression of sodium channel α-subunits and A-type fibroblast growth factor homologous factors (FHFs). Specifically, A-type FHFs induces INaR from Nav1.8, Nav1.9 tetrodotoxin-resistant neuronal channels and, to a lesser extent, neuronal Nav1.7 and cardiac Nav1.5 channels. Moreover, we identified the N-terminus of FHF as the critical molecule responsible for A-type FHFs-mediated INaR. Among the FHFs, FHF4A is the most important isoform for mediating Nav1.8 and Nav1.9 INaR. In nociceptive sensory neurons, FHF4A knockdown significantly reduces INaR amplitude and the percentage of neurons that generate INaR, substantially suppressing excitability. Thus, our work reveals a novel molecular mechanism underlying TTX-resistant INaR generation and provides important potential targets for pain treatment.
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Affiliation(s)
- Yucheng Xiao
- Biology Department, Indiana University - Purdue University Indianapolis, Indianapolis, United States
| | | | - Agnes Zybura
- Paul and Carole Stark Neurosciences Research Institute, Indiana University, Indianapolis, United States
| | - Yanling Pan
- Biology Department, Indiana University - Purdue University Indianapolis, Indianapolis, United States
| | | | - Theodore R Cummins
- Biology Department, Indiana University - Purdue University Indianapolis, Indianapolis, United States
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10
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Daimi H, Lozano-Velasco E, Aranega A, Franco D. Genomic and Non-Genomic Regulatory Mechanisms of the Cardiac Sodium Channel in Cardiac Arrhythmias. Int J Mol Sci 2022; 23:1381. [PMID: 35163304 PMCID: PMC8835759 DOI: 10.3390/ijms23031381] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 12/30/2021] [Accepted: 01/06/2022] [Indexed: 12/19/2022] Open
Abstract
Nav1.5 is the predominant cardiac sodium channel subtype, encoded by the SCN5A gene, which is involved in the initiation and conduction of action potentials throughout the heart. Along its biosynthesis process, Nav1.5 undergoes strict genomic and non-genomic regulatory and quality control steps that allow only newly synthesized channels to reach their final membrane destination and carry out their electrophysiological role. These regulatory pathways are ensured by distinct interacting proteins that accompany the nascent Nav1.5 protein along with different subcellular organelles. Defects on a large number of these pathways have a tremendous impact on Nav1.5 functionality and are thus intimately linked to cardiac arrhythmias. In the present review, we provide current state-of-the-art information on the molecular events that regulate SCN5A/Nav1.5 and the cardiac channelopathies associated with defects in these pathways.
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Affiliation(s)
- Houria Daimi
- Biochemistry and Molecular Biology Laboratory, Faculty of Pharmacy, University of Monastir, Monastir 5000, Tunisia
| | - Estefanía Lozano-Velasco
- Department of Experimental Biology, University of Jaen, 23071 Jaen, Spain; (E.L.-V.); (A.A.); (D.F.)
- Medina Foundation, Technology Park of Health Sciences, Av. del Conocimiento, 34, 18016 Granada, Spain
| | - Amelia Aranega
- Department of Experimental Biology, University of Jaen, 23071 Jaen, Spain; (E.L.-V.); (A.A.); (D.F.)
- Medina Foundation, Technology Park of Health Sciences, Av. del Conocimiento, 34, 18016 Granada, Spain
| | - Diego Franco
- Department of Experimental Biology, University of Jaen, 23071 Jaen, Spain; (E.L.-V.); (A.A.); (D.F.)
- Medina Foundation, Technology Park of Health Sciences, Av. del Conocimiento, 34, 18016 Granada, Spain
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11
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Yu Y, Yang J, Luan F, Gu G, Zhao R, Wang Q, Dong Z, Tang J, Wang W, Sun J, Lv P, Zhang H, Wang C. Sensorineural Hearing Loss and Mitochondrial Apoptosis of Cochlear Spiral Ganglion Neurons in Fibroblast Growth Factor 13 Knockout Mice. Front Cell Neurosci 2021; 15:658586. [PMID: 34220452 PMCID: PMC8242186 DOI: 10.3389/fncel.2021.658586] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 04/26/2021] [Indexed: 12/17/2022] Open
Abstract
Deafness is known to occur in more than 400 syndromes and accounts for almost 30% of hereditary hearing loss. The molecular mechanisms underlying such syndromic deafness remain unclear. Furthermore, deafness has been a common feature in patients with three main syndromes, the BÖrjeson-Forssman-Lehmann syndrome, Wildervanck syndrome, and Congenital Generalized Hirsutism, all of which are characterized by loss-of-function mutations in the Fgf13 gene. Whether the pathogenesis of deafness in these syndromes is associated with the Fgf13 mutation is not known. To elucidate its role in auditory function, we generated a mouse line with conditional knockout of the Fgf13 gene in the inner ear (Fgf13 cKO). FGF13 is expressed predominantly in the organ of Corti, spiral ganglion neurons (SGNs), stria vascularis, and the supporting cells. Conditional knockout of the gene in the inner ear led to sensorineural deafness with low amplitude and increased latency of wave I in the auditory brainstem response test but had a normal distortion product otoacoustic emission threshold. Fgf13 deficiency resulted in decreased SGN density from the apical to the basal region without significant morphological changes and those in the number of hair cells. TUNEL and caspase-3 immunocytochemistry assays showed that apoptotic cell death mediated the loss of SGNs. Further detection of apoptotic factors through qRT-PCR suggested the activation of the mitochondrial apoptotic pathway in SGNs. Together, this study reveals a novel role for Fgf13 in auditory function, and indicates that the gene could be a potential candidate for understanding deafness. These findings may provide new perspectives on the molecular mechanisms and novel therapeutic targets for treatment deafness.
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Affiliation(s)
- Yulou Yu
- The Key Laboratory of Neural and Vascular Biology, Ministry of Education, Hebei Medical University, Shijiazhuang, China.,The Key Laboratory of New Drug Pharmacology and Toxicology, Department of Pharmacology, Hebei Medical University, Shijiazhuang, China
| | - Jing Yang
- Department of Physiology, Hebei Medical University, Shijiazhuang, China
| | - Feng Luan
- Department of Otolaryngology, The Third Hospital of Hebei Medical University, Shijiazhuang, China
| | - Guoqiang Gu
- Department of Cardiology, The Second Hospital of Hebei Medical University, Shijiazhuang, China
| | - Ran Zhao
- The Key Laboratory of Neural and Vascular Biology, Ministry of Education, Hebei Medical University, Shijiazhuang, China.,The Key Laboratory of New Drug Pharmacology and Toxicology, Department of Pharmacology, Hebei Medical University, Shijiazhuang, China
| | - Qiong Wang
- The Key Laboratory of Neural and Vascular Biology, Ministry of Education, Hebei Medical University, Shijiazhuang, China.,The Key Laboratory of New Drug Pharmacology and Toxicology, Department of Pharmacology, Hebei Medical University, Shijiazhuang, China
| | - Zishan Dong
- The Key Laboratory of Neural and Vascular Biology, Ministry of Education, Hebei Medical University, Shijiazhuang, China.,The Key Laboratory of New Drug Pharmacology and Toxicology, Department of Pharmacology, Hebei Medical University, Shijiazhuang, China
| | - Junming Tang
- Hubei Key Laboratory of Embryonic Stem Cell Research, Hubei University of Medicine, Shiyan, China
| | - Wei Wang
- Department of Physiology, Hebei Medical University, Shijiazhuang, China
| | - Jinpeng Sun
- Key Laboratory Experimental Teratology of the Ministry of Education, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Ping Lv
- The Key Laboratory of Neural and Vascular Biology, Ministry of Education, Hebei Medical University, Shijiazhuang, China.,The Key Laboratory of New Drug Pharmacology and Toxicology, Department of Pharmacology, Hebei Medical University, Shijiazhuang, China
| | - Hailin Zhang
- The Key Laboratory of Neural and Vascular Biology, Ministry of Education, Hebei Medical University, Shijiazhuang, China.,The Key Laboratory of New Drug Pharmacology and Toxicology, Department of Pharmacology, Hebei Medical University, Shijiazhuang, China
| | - Chuan Wang
- The Key Laboratory of Neural and Vascular Biology, Ministry of Education, Hebei Medical University, Shijiazhuang, China.,The Key Laboratory of New Drug Pharmacology and Toxicology, Department of Pharmacology, Hebei Medical University, Shijiazhuang, China
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12
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Tylock KM, Auerbach DS, Tang ZZ, Thornton CA, Dirksen RT. Biophysical mechanisms for QRS- and QTc-interval prolongation in mice with cardiac expression of expanded CUG-repeat RNA. J Gen Physiol 2021; 152:133632. [PMID: 31968060 PMCID: PMC7062505 DOI: 10.1085/jgp.201912450] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 10/28/2019] [Accepted: 11/26/2019] [Indexed: 12/26/2022] Open
Abstract
Myotonic dystrophy type 1 (DM1), the most common form of muscular dystrophy in adults, results from the expression of toxic gain-of-function transcripts containing expanded CUG-repeats. DM1 patients experience cardiac electrophysiological defects, including prolonged PR-, QRS-, and QT-intervals, that increase susceptibility to sudden cardiac death (SCD). However, the specific biophysical and molecular mechanisms that underlie the electrocardiograph (ECG) abnormalities and SCD in DM1 are unclear. Here, we addressed this issue using a novel transgenic mouse model that exhibits robust cardiac expression of expanded CUG-repeat RNA (LC15 mice). ECG measurements in conscious LC15 mice revealed significantly prolonged QRS- and corrected QT-intervals, but a normal PR-interval. Although spontaneous arrhythmias were not observed in conscious LC15 mice under nonchallenged conditions, acute administration of the sodium channel blocker flecainide prolonged the QRS-interval and unveiled an increased susceptibility to lethal ventricular arrhythmias. Current clamp measurements in ventricular myocytes from LC15 mice revealed significantly reduced action potential upstroke velocity at physiological pacing (9 Hz) and prolonged action potential duration at all stimulation rates (1–9 Hz). Voltage clamp experiments revealed significant rightward shifts in the voltage dependence of sodium channel activation and steady-state inactivation, as well as a marked reduction in outward potassium current density. Together, these findings indicate that expression of expanded CUG-repeat RNA in the murine heart results in reduced sodium and potassium channel activity that results in QRS- and QT-interval prolongation, respectively.
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Affiliation(s)
- Kevin M Tylock
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY
| | - David S Auerbach
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY.,Department of Pharmacology, Upstate Medical University, Syracuse, NY
| | - Zhen Zhi Tang
- Department of Neurology, University of Rochester Medical Center, Rochester, NY
| | - Charles A Thornton
- Department of Neurology, University of Rochester Medical Center, Rochester, NY
| | - Robert T Dirksen
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY
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13
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Khosravi F, Ahmadvand N, Bellusci S, Sauer H. The Multifunctional Contribution of FGF Signaling to Cardiac Development, Homeostasis, Disease and Repair. Front Cell Dev Biol 2021; 9:672935. [PMID: 34095143 PMCID: PMC8169986 DOI: 10.3389/fcell.2021.672935] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 04/20/2021] [Indexed: 12/13/2022] Open
Abstract
The current focus on cardiovascular research reflects society’s concerns regarding the alarming incidence of cardiac-related diseases and mortality in the industrialized world and, notably, an urgent need to combat them by more efficient therapies. To pursue these therapeutic approaches, a comprehensive understanding of the mechanism of action for multifunctional fibroblast growth factor (FGF) signaling in the biology of the heart is a matter of high importance. The roles of FGFs in heart development range from outflow tract formation to the proliferation of cardiomyocytes and the formation of heart chambers. In the context of cardiac regeneration, FGFs 1, 2, 9, 16, 19, and 21 mediate adaptive responses including restoration of cardiac contracting rate after myocardial infarction and reduction of myocardial infarct size. However, cardiac complications in human diseases are correlated with pathogenic effects of FGF ligands and/or FGF signaling impairment. FGFs 2 and 23 are involved in maladaptive responses such as cardiac hypertrophic, fibrotic responses and heart failure. Among FGFs with known causative (FGFs 2, 21, and 23) or protective (FGFs 2, 15/19, 16, and 21) roles in cardiac diseases, FGFs 15/19, 21, and 23 display diagnostic potential. The effective role of FGFs on the induction of progenitor stem cells to cardiac cells during development has been employed to boost the limited capacity of postnatal cardiac repair. To renew or replenish damaged cardiomyocytes, FGFs 1, 2, 10, and 16 were tested in (induced-) pluripotent stem cell-based approaches and for stimulation of cell cycle re-entry in adult cardiomyocytes. This review will shed light on the wide range of beneficiary and detrimental actions mediated by FGF ligands and their receptors in the heart, which may open new therapeutic avenues for ameliorating cardiac complications.
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Affiliation(s)
- Farhad Khosravi
- Department of Physiology, Justus Liebig University Giessen, Giessen, Germany
| | - Negah Ahmadvand
- Cardio-Pulmonary Institute, Justus Liebig University Giessen, Giessen, Germany
| | - Saverio Bellusci
- Cardio-Pulmonary Institute, Justus Liebig University Giessen, Giessen, Germany
| | - Heinrich Sauer
- Department of Physiology, Justus Liebig University Giessen, Giessen, Germany
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14
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Martinez-Espinosa PL, Yang C, Xia XM, Lingle CJ. Nav1.3 and FGF14 are primary determinants of the TTX-sensitive sodium current in mouse adrenal chromaffin cells. J Gen Physiol 2021; 153:211839. [PMID: 33651884 PMCID: PMC8020717 DOI: 10.1085/jgp.202012785] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Revised: 01/07/2021] [Accepted: 01/19/2021] [Indexed: 12/29/2022] Open
Abstract
Adrenal chromaffin cells (CCs) in rodents express rapidly inactivating, tetrodotoxin (TTX)-sensitive sodium channels. The resulting current has generally been attributed to Nav1.7, although a possible role for Nav1.3 has also been suggested. Nav channels in rat CCs rapidly inactivate via two independent pathways which differ in their time course of recovery. One subpopulation recovers with time constants similar to traditional fast inactivation and the other ∼10-fold slower, but both pathways can act within a single homogenous population of channels. Here, we use Nav1.3 KO mice to probe the properties and molecular components of Nav current in CCs. We find that the absence of Nav1.3 abolishes all Nav current in about half of CCs examined, while a small, fast inactivating Nav current is still observed in the rest. To probe possible molecular components underlying slow recovery from inactivation, we used mice null for fibroblast growth factor homology factor 14 (FGF14). In these cells, the slow component of recovery from fast inactivation is completely absent in most CCs, with no change in the time constant of fast recovery. The use dependence of Nav current reduction during trains of stimuli in WT cells is completely abolished in FGF14 KO mice, directly demonstrating a role for slow recovery from inactivation in determining Nav current availability. Our results indicate that FGF14-mediated inactivation is the major determinant defining use-dependent changes in Nav availability in CCs. These results establish that Nav1.3, like other Nav isoforms, can also partner with FGF subunits, strongly regulating Nav channel function.
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Affiliation(s)
| | - Chengtao Yang
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO
| | - Xiao-Ming Xia
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO
| | - Christopher J Lingle
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO
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15
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Mahling R, Rahlf CR, Hansen SC, Hayden MR, Shea MA. Ca 2+-saturated calmodulin binds tightly to the N-terminal domain of A-type fibroblast growth factor homologous factors. J Biol Chem 2021; 296:100458. [PMID: 33639159 PMCID: PMC8059062 DOI: 10.1016/j.jbc.2021.100458] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 02/15/2021] [Accepted: 02/23/2021] [Indexed: 01/12/2023] Open
Abstract
Voltage-gated sodium channels (Navs) are tightly regulated by multiple conserved auxiliary proteins, including the four fibroblast growth factor homologous factors (FGFs), which bind the Nav EF-hand like domain (EFL), and calmodulin (CaM), a multifunctional messenger protein that binds the NaV IQ motif. The EFL domain and IQ motif are contiguous regions of NaV cytosolic C-terminal domains (CTD), placing CaM and FGF in close proximity. However, whether the FGFs and CaM act independently, directly associate, or operate through allosteric interactions to regulate channel function is unknown. Titrations monitored by steady-state fluorescence spectroscopy, structural studies with solution NMR, and computational modeling demonstrated for the first time that both domains of (Ca2+)4-CaM (but not apo CaM) directly bind two sites in the N-terminal domain (NTD) of A-type FGF splice variants (FGF11A, FGF12A, FGF13A, and FGF14A) with high affinity. The weaker of the (Ca2+)4-CaM-binding sites was known via electrophysiology to have a role in long-term inactivation of the channel but not known to bind CaM. FGF12A binding to a complex of CaM associated with a fragment of the NaV1.2 CTD increased the Ca2+-binding affinity of both CaM domains, consistent with (Ca2+)4-CaM interacting preferentially with its higher-affinity site in the FGF12A NTD. Thus, A-type FGFs can compete with NaV IQ motifs for (Ca2+)4-CaM. During spikes in the cytosolic Ca2+ concentration that accompany an action potential, CaM may translocate from the NaV IQ motif to the FGF NTD, or the A-type FGF NTD may recruit a second molecule of CaM to the channel.
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Affiliation(s)
- Ryan Mahling
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Cade R Rahlf
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Samuel C Hansen
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Matthew R Hayden
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
| | - Madeline A Shea
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA.
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16
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Joglekar A, Prjibelski A, Mahfouz A, Collier P, Lin S, Schlusche AK, Marrocco J, Williams SR, Haase B, Hayes A, Chew JG, Weisenfeld NI, Wong MY, Stein AN, Hardwick SA, Hunt T, Wang Q, Dieterich C, Bent Z, Fedrigo O, Sloan SA, Risso D, Jarvis ED, Flicek P, Luo W, Pitt GS, Frankish A, Smit AB, Ross ME, Tilgner HU. A spatially resolved brain region- and cell type-specific isoform atlas of the postnatal mouse brain. Nat Commun 2021; 12:463. [PMID: 33469025 PMCID: PMC7815907 DOI: 10.1038/s41467-020-20343-5] [Citation(s) in RCA: 99] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Accepted: 11/27/2020] [Indexed: 01/19/2023] Open
Abstract
Splicing varies across brain regions, but the single-cell resolution of regional variation is unclear. We present a single-cell investigation of differential isoform expression (DIE) between brain regions using single-cell long-read sequencing in mouse hippocampus and prefrontal cortex in 45 cell types at postnatal day 7 ( www.isoformAtlas.com ). Isoform tests for DIE show better performance than exon tests. We detect hundreds of DIE events traceable to cell types, often corresponding to functionally distinct protein isoforms. Mostly, one cell type is responsible for brain-region specific DIE. However, for fewer genes, multiple cell types influence DIE. Thus, regional identity can, although rarely, override cell-type specificity. Cell types indigenous to one anatomic structure display distinctive DIE, e.g. the choroid plexus epithelium manifests distinct transcription-start-site usage. Spatial transcriptomics and long-read sequencing yield a spatially resolved splicing map. Our methods quantify isoform expression with cell-type and spatial resolution and it contributes to further our understanding of how the brain integrates molecular and cellular complexity.
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Affiliation(s)
- Anoushka Joglekar
- Brain and Mind Research Institute and Center for Neurogenetics, Weill Cornell Medicine, New York, NY, USA
| | - Andrey Prjibelski
- Center for Algorithmic Biotechnology, Institute of Translational Biomedicine, St. Petersburg State University, St Petersburg, Russia
| | - Ahmed Mahfouz
- Department of Human Genetics, Leiden University Medical Center, Leiden, 2333 ZC, The Netherlands
- Leiden Computational Biology Center, Leiden University Medical Center, Leiden, 2333 ZC, The Netherlands
- Delft Bioinformatics Lab, Delft University of Technology, Delft, 2628 XE, The Netherlands
| | - Paul Collier
- Brain and Mind Research Institute and Center for Neurogenetics, Weill Cornell Medicine, New York, NY, USA
| | - Susan Lin
- Graduate Program in Neuroscience, Weill Cornell Medical College, 1300 York Avenue, New York, NY, 10065, USA
- Cardiovascular Research Institute, Weill Cornell Medicine, New York, NY, USA
| | - Anna Katharina Schlusche
- Brain and Mind Research Institute and Center for Neurogenetics, Weill Cornell Medicine, New York, NY, USA
| | - Jordan Marrocco
- Harold and Margaret Milliken Hatch Laboratory of Neuroendocrinology, The Rockefeller University, New York, NY, USA
| | | | - Bettina Haase
- The Vertebrate Genomes Lab, The Rockefeller University, New York, NY, USA
| | | | | | | | - Man Ying Wong
- Brain and Mind Research Institute and Appel Alzheimer's Research Institute, Weill Cornell Medicine, New York, NY, USA
| | | | - Simon A Hardwick
- Brain and Mind Research Institute and Center for Neurogenetics, Weill Cornell Medicine, New York, NY, USA
- Genomics and Epigenetics Division, Garvan Institute of Medical Research, Sydney, NSW, Australia
| | - Toby Hunt
- European Molecular Biology Laboratory, European Bioinformatics Institute, Hinxton, UK
| | - Qi Wang
- Section of Bioinformatics and Systems Cardiology, University Hospital, 96120, Heidelberg, Germany
| | - Christoph Dieterich
- Section of Bioinformatics and Systems Cardiology, University Hospital, 96120, Heidelberg, Germany
| | | | - Olivier Fedrigo
- The Vertebrate Genomes Lab, The Rockefeller University, New York, NY, USA
| | - Steven A Sloan
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA, USA
| | - Davide Risso
- Department of Statistical Sciences, University of Padova, Padova, Italy
| | - Erich D Jarvis
- The Vertebrate Genomes Lab, The Rockefeller University, New York, NY, USA
- Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - Paul Flicek
- European Molecular Biology Laboratory, European Bioinformatics Institute, Hinxton, UK
| | - Wenjie Luo
- Brain and Mind Research Institute and Appel Alzheimer's Research Institute, Weill Cornell Medicine, New York, NY, USA
| | - Geoffrey S Pitt
- Graduate Program in Neuroscience, Weill Cornell Medical College, 1300 York Avenue, New York, NY, 10065, USA
- Cardiovascular Research Institute, Weill Cornell Medicine, New York, NY, USA
| | - Adam Frankish
- European Molecular Biology Laboratory, European Bioinformatics Institute, Hinxton, UK
| | - August B Smit
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University, Amsterdam, The Netherlands
| | - M Elizabeth Ross
- Brain and Mind Research Institute and Center for Neurogenetics, Weill Cornell Medicine, New York, NY, USA
| | - Hagen U Tilgner
- Brain and Mind Research Institute and Center for Neurogenetics, Weill Cornell Medicine, New York, NY, USA.
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17
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Wang Q, Yang J, Wang H, Shan B, Yin C, Yu H, Zhang X, Dong Z, Yu Y, Zhao R, Liu B, Zhang H, Wang C. Fibroblast growth factor 13 stabilizes microtubules to promote Na + channel function in nociceptive DRG neurons and modulates inflammatory pain. J Adv Res 2020; 31:97-111. [PMID: 34194835 PMCID: PMC8240113 DOI: 10.1016/j.jare.2020.12.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 11/16/2020] [Accepted: 12/14/2020] [Indexed: 11/28/2022] Open
Abstract
Introduction Fibroblast growth factor homologous factors (FHFs), among other fibroblast growth factors, are increasingly found to be important regulators of ion channel functions. Although FHFs have been link to several neuronal diseases and arrhythmia, its role in inflammatory pain still remains unclear. Objectives This study aimed to investigate the role and mechanism of FGF13 in inflammatory pain. Methods Fgf13 conditional knockout mice were generated and CFA-induced chronic inflammatory pain model was established to measure the pain threshold. Immunostaining, western blot and quantitative real-time reverse transcription PCR (qRT-PCR) were performed to detect the expression of FGF13 in CFA-induced inflammatory pain. Whole-cell patch clamp recording was used to record the action potential firing properties and sodium currents of DRG neurons. Results Conditional knockout of Fgf13 in dorsal root ganglion (DRG) neurons (Fgf13-/Y) led to attenuated pain responses induced by complete Freund's adjuvant (CFA). FGF13 was expressed predominantly in small-diameter DRG neurons. CFA treatment resulted in an increased expression of FGF13 proteins as well as an increased excitability in nociceptive DRG neurons which was inhibited when FGF13 was absent. The role of FGF13 in neuronal excitability of DRG was linked to its modulation of voltage-gated Na+ channels mediated by microtubules. Overexpression of FGF13, but not FGF13 mutant which lacks the ability to bind and stabilize microtubules, rescued the decreased neuronal excitability and Na+ current density in DRG neurons of Fgf13-/Y mice. Conclusion This study revealed that FGF13 could stabilize microtubules to modulate sodium channel function in DRG neurons and modulate inflammatory pain. This study provides a novel mechanism for FGF13 modulation of sodium channel function and suggests that FGF13 might be a novel target for inflammatory pain treatment.
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Affiliation(s)
- Qiong Wang
- Department of Pharmacology, Hebei Medical University, Shijiazhuang 050017, China
| | - Jing Yang
- Department of Physiology, Hebei Medical University, Shijiazhuang 050017, China
| | - Handong Wang
- College of Basic Medicine, Hebei Medical University, Shijiazhuang 050017, China
| | - Bin Shan
- Department of Pharmacy, The Forth Hospital of Hebei Medical University, Shijiazhuang 050017, China
| | - Chengyu Yin
- Department of Neurobiology and Acupuncture Research, The Third Clinical Medical College, Zhejiang Chinese Medical University, Key Laboratory of Acupuncture and Neurology of Zhejiang Province, Hangzhou 310053, China
| | - Hang Yu
- College of Basic Medicine, Hebei Medical University, Shijiazhuang 050017, China
| | - Xuerou Zhang
- College of Basic Medicine, Hebei Medical University, Shijiazhuang 050017, China
| | - Zishan Dong
- Department of Pharmacology, Hebei Medical University, Shijiazhuang 050017, China
| | - Yulou Yu
- Department of Pharmacology, Hebei Medical University, Shijiazhuang 050017, China
| | - Ran Zhao
- Department of Pharmacology, Hebei Medical University, Shijiazhuang 050017, China
| | - Boyi Liu
- Department of Neurobiology and Acupuncture Research, The Third Clinical Medical College, Zhejiang Chinese Medical University, Key Laboratory of Acupuncture and Neurology of Zhejiang Province, Hangzhou 310053, China
| | - Hailin Zhang
- Department of Pharmacology, Hebei Medical University, Shijiazhuang 050017, China
| | - Chuan Wang
- Department of Pharmacology, Hebei Medical University, Shijiazhuang 050017, China
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18
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Abrams J, Roybal D, Chakouri N, Katchman AN, Weinberg R, Yang L, Chen BX, Zakharov SI, Hennessey JA, Avula UMR, Diaz J, Wang C, Wan EY, Pitt GS, Ben-Johny M, Marx SO. Fibroblast growth factor homologous factors tune arrhythmogenic late NaV1.5 current in calmodulin binding-deficient channels. JCI Insight 2020; 5:141736. [PMID: 32870823 PMCID: PMC7566708 DOI: 10.1172/jci.insight.141736] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Accepted: 08/26/2020] [Indexed: 12/19/2022] Open
Abstract
The Ca2+-binding protein calmodulin has emerged as a pivotal player in tuning Na+ channel function, although its impact in vivo remains to be resolved. Here, we identify the role of calmodulin and the NaV1.5 interactome in regulating late Na+ current in cardiomyocytes. We created transgenic mice with cardiac-specific expression of human NaV1.5 channels with alanine substitutions for the IQ motif (IQ/AA). The mutations rendered the channels incapable of binding calmodulin to the C-terminus. The IQ/AA transgenic mice exhibited normal ventricular repolarization without arrhythmias and an absence of increased late Na+ current. In comparison, transgenic mice expressing a lidocaine-resistant (F1759A) human NaV1.5 demonstrated increased late Na+ current and prolonged repolarization in cardiomyocytes, with spontaneous arrhythmias. To determine regulatory factors that prevent late Na+ current for the IQ/AA mutant channel, we considered fibroblast growth factor homologous factors (FHFs), which are within the NaV1.5 proteomic subdomain shown by proximity labeling in transgenic mice expressing NaV1.5 conjugated to ascorbate peroxidase. We found that FGF13 diminished late current of the IQ/AA but not F1759A mutant cardiomyocytes, suggesting that endogenous FHFs may serve to prevent late Na+ current in mouse cardiomyocytes. Leveraging endogenous mechanisms may furnish an alternative avenue for developing novel pharmacology that selectively blunts late Na+ current.
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Affiliation(s)
| | | | - Nourdine Chakouri
- Department of Physiology and Cellular Biophysics, Vagelos College of Physicians and Surgeons, Columbia University, New York, New York, USA
| | | | | | - Lin Yang
- Division of Cardiology, Department of Medicine
| | | | | | | | | | - Johanna Diaz
- Department of Physiology and Cellular Biophysics, Vagelos College of Physicians and Surgeons, Columbia University, New York, New York, USA
| | - Chaojian Wang
- Division of Cardiology, Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA
| | | | - Geoffrey S. Pitt
- Cardiovascular Research Institute, Weill Cornell Medical College, New York, New York, USA
| | - Manu Ben-Johny
- Department of Physiology and Cellular Biophysics, Vagelos College of Physicians and Surgeons, Columbia University, New York, New York, USA
| | - Steven O. Marx
- Division of Cardiology, Department of Medicine
- Department of Pharmacology, and
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19
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Brewer KR, Kuenze G, Vanoye CG, George AL, Meiler J, Sanders CR. Structures Illuminate Cardiac Ion Channel Functions in Health and in Long QT Syndrome. Front Pharmacol 2020; 11:550. [PMID: 32431610 PMCID: PMC7212895 DOI: 10.3389/fphar.2020.00550] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Accepted: 04/09/2020] [Indexed: 12/13/2022] Open
Abstract
The cardiac action potential is critical to the production of a synchronized heartbeat. This electrical impulse is governed by the intricate activity of cardiac ion channels, among them the cardiac voltage-gated potassium (Kv) channels KCNQ1 and hERG as well as the voltage-gated sodium (Nav) channel encoded by SCN5A. Each channel performs a highly distinct function, despite sharing a common topology and structural components. These three channels are also the primary proteins mutated in congenital long QT syndrome (LQTS), a genetic condition that predisposes to cardiac arrhythmia and sudden cardiac death due to impaired repolarization of the action potential and has a particular proclivity for reentrant ventricular arrhythmias. Recent cryo-electron microscopy structures of human KCNQ1 and hERG, along with the rat homolog of SCN5A and other mammalian sodium channels, provide atomic-level insight into the structure and function of these proteins that advance our understanding of their distinct functions in the cardiac action potential, as well as the molecular basis of LQTS. In this review, the gating, regulation, LQTS mechanisms, and pharmacological properties of KCNQ1, hERG, and SCN5A are discussed in light of these recent structural findings.
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Affiliation(s)
- Kathryn R. Brewer
- Center for Structural Biology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, United States
- Department of Biochemistry, Vanderbilt University, Nashville, TN, United States
| | - Georg Kuenze
- Center for Structural Biology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, United States
- Department of Chemistry, Vanderbilt University, Nashville, TN, United States
| | - Carlos G. Vanoye
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Alfred L. George
- Department of Pharmacology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Jens Meiler
- Center for Structural Biology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, United States
- Department of Chemistry, Vanderbilt University, Nashville, TN, United States
- Department of Pharmacology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, United States
- Institute for Drug Discovery, Leipzig University Medical School, Leipzig, Germany
| | - Charles R. Sanders
- Center for Structural Biology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, United States
- Department of Biochemistry, Vanderbilt University, Nashville, TN, United States
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20
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Sochacka M, Opalinski L, Szymczyk J, Zimoch MB, Czyrek A, Krowarsch D, Otlewski J, Zakrzewska M. FHF1 is a bona fide fibroblast growth factor that activates cellular signaling in FGFR-dependent manner. Cell Commun Signal 2020; 18:69. [PMID: 32357892 PMCID: PMC7193404 DOI: 10.1186/s12964-020-00573-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Accepted: 04/01/2020] [Indexed: 12/22/2022] Open
Abstract
Abstract Fibroblast growth factors (FGFs) via their receptors (FGFRs) transduce signals from the extracellular space to the cell interior, modulating pivotal cellular processes such as cell proliferation, motility, metabolism and death. FGF superfamily includes a group of fibroblast growth factor homologous factors (FHFs), proteins whose function is still largely unknown. Since FHFs lack the signal sequence for secretion and are unable to induce FGFR-dependent cell proliferation, these proteins were considered as intracellular proteins that are not involved in signal transduction via FGFRs. Here we demonstrate for the first time that FHF1 directly interacts with all four major FGFRs. FHF1 binding causes efficient FGFR activation and initiation of receptor-dependent signaling cascades. However, the biological effect of FHF1 differs from the one elicited by canonical FGFs, as extracellular FHF1 protects cells from apoptosis, but is unable to stimulate cell division. Our data define FHF1 as a FGFR ligand, emphasizing much greater similarity between FHFs and canonical FGFs than previously indicated. Video Abstract. (MP4 38460 kb)
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Affiliation(s)
- Martyna Sochacka
- Department of Protein Engineering, Faculty of Biotechnology, University of Wroclaw, Joliot-Curie 14a, 50-383, Wroclaw, Poland
| | - Lukasz Opalinski
- Department of Protein Engineering, Faculty of Biotechnology, University of Wroclaw, Joliot-Curie 14a, 50-383, Wroclaw, Poland
| | - Jakub Szymczyk
- Department of Protein Engineering, Faculty of Biotechnology, University of Wroclaw, Joliot-Curie 14a, 50-383, Wroclaw, Poland
| | - Marta B Zimoch
- Department of Protein Engineering, Faculty of Biotechnology, University of Wroclaw, Joliot-Curie 14a, 50-383, Wroclaw, Poland
| | - Aleksandra Czyrek
- Department of Protein Engineering, Faculty of Biotechnology, University of Wroclaw, Joliot-Curie 14a, 50-383, Wroclaw, Poland
| | - Daniel Krowarsch
- Department of Protein Biotechnology, Faculty of Biotechnology, University of Wroclaw, Joliot-Curie 14a, 50-383, Wroclaw, Poland
| | - Jacek Otlewski
- Department of Protein Engineering, Faculty of Biotechnology, University of Wroclaw, Joliot-Curie 14a, 50-383, Wroclaw, Poland
| | - Malgorzata Zakrzewska
- Department of Protein Engineering, Faculty of Biotechnology, University of Wroclaw, Joliot-Curie 14a, 50-383, Wroclaw, Poland.
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21
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Takla M, Huang CLH, Jeevaratnam K. The cardiac CaMKII-Na v1.5 relationship: From physiology to pathology. J Mol Cell Cardiol 2020; 139:190-200. [PMID: 31958466 DOI: 10.1016/j.yjmcc.2019.12.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Revised: 11/20/2019] [Accepted: 12/30/2019] [Indexed: 12/19/2022]
Abstract
The SCN5A gene encodes Nav1.5, which, as the cardiac voltage-gated Na+ channel's pore-forming α subunit, is crucial for the initiation and propagation of atrial and ventricular action potentials. The arrhythmogenic propensity of inherited SCN5A mutations implicates the Na+ channel in determining cardiomyocyte excitability under normal conditions. Cytosolic kinases have long been known to alter the kinetic profile of Nav1.5 inactivation via phosphorylation of specific residues. Recent substantiation of both the role of calmodulin-dependent kinase II (CaMKII) in modulating the properties of the Nav1.5 inactivation gate and the significant rise in oxidation-dependent autonomous CaMKII activity in structural heart disease has raised the possibility of a novel pathway for acquired arrhythmias - the CaMKII-Nav1.5 relationship. The aim of this review is to: (1) outline the relationship's translation from physiological adaptation to pathological vicious circle; and (2) discuss the relative merits of each of its components as pharmacological targets.
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Affiliation(s)
- Michael Takla
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, GU2 7AL, United Kingdom
| | - Christopher L-H Huang
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, GU2 7AL, United Kingdom; Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, CB2 3EG, United Kingdom
| | - Kamalan Jeevaratnam
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, GU2 7AL, United Kingdom; Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, CB2 3EG, United Kingdom.
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22
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Sinden DS, Holman CD, Bare CJ, Sun X, Gade AR, Cohen DE, Pitt GS. Knockout of the X-linked Fgf13 in the hypothalamic paraventricular nucleus impairs sympathetic output to brown fat and causes obesity. FASEB J 2019; 33:11579-11594. [PMID: 31339804 PMCID: PMC6994920 DOI: 10.1096/fj.201901178r] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 07/01/2019] [Indexed: 12/15/2022]
Abstract
Fibroblast growth factor (FGF)13, a nonsecreted, X-linked, FGF homologous factor, is differentially expressed in adipocytes in response to diet, yet Fgf13's role in metabolism has not been explored. Heterozygous Fgf13 knockouts fed normal chow and housed at 22°C showed hyperactivity accompanying reduced core temperature and obesity when housed at 30°C. Those heterozygous knockouts showed defects in thermogenesis even at 30°C and an inability to protect core temperature. Surprisingly, we detected trivial FGF13 in adipose of wild-type mice fed normal chow and no obesity in adipose-specific heterozygous knockouts housed at 30°C, and we detected an intact brown fat response through exogenous β3 agonist stimulation, suggesting a defect in sympathetic drive to brown adipose tissue. In contrast, hypothalamic-specific ablation of Fgf13 recapitulated weight gain at 30°C. Norepinephrine turnover in brown fat was reduced at both housing temperatures. Thus, our data suggest that impaired CNS regulation of sympathetic activation of brown fat underlies obesity and thermogenesis in Fgf13 heterozygous knockouts fed normal chow.-Sinden, D. S., Holman, C. D., Bare, C. J., Sun, X., Gade, A. R., Cohen, D. E., Pitt, G. S. Knockout of the X-linked Fgf13 in the hypothalamic paraventricular nucleus impairs sympathetic output to brown fat and causes obesity.
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Affiliation(s)
- Daniel S. Sinden
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina, USA
- Cardiovascular Research Institute, Weill Cornell Medical College, New York, New York, USA
| | - Corey D. Holman
- Division of Gastroenterology and Hepatology, Weill Cornell Medical College, New York, New York, USA
| | - Curtis J. Bare
- Division of Gastroenterology and Hepatology, Weill Cornell Medical College, New York, New York, USA
| | - Xiaolu Sun
- Cardiovascular Research Institute, Weill Cornell Medical College, New York, New York, USA
| | - Aravind R. Gade
- Cardiovascular Research Institute, Weill Cornell Medical College, New York, New York, USA
| | - David E. Cohen
- Division of Gastroenterology and Hepatology, Weill Cornell Medical College, New York, New York, USA
| | - Geoffrey S. Pitt
- Cardiovascular Research Institute, Weill Cornell Medical College, New York, New York, USA
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23
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Burel S, Coyan FC, Lorenzini M, Meyer MR, Lichti CF, Brown JH, Loussouarn G, Charpentier F, Nerbonne JM, Townsend RR, Maier LS, Marionneau C. C-terminal phosphorylation of Na V1.5 impairs FGF13-dependent regulation of channel inactivation. J Biol Chem 2017; 292:17431-17448. [PMID: 28882890 PMCID: PMC5655519 DOI: 10.1074/jbc.m117.787788] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Revised: 08/23/2017] [Indexed: 11/06/2022] Open
Abstract
Voltage-gated Na+ (NaV) channels are key regulators of myocardial excitability, and Ca2+/calmodulin-dependent protein kinase II (CaMKII)-dependent alterations in NaV1.5 channel inactivation are emerging as a critical determinant of arrhythmias in heart failure. However, the global native phosphorylation pattern of NaV1.5 subunits associated with these arrhythmogenic disorders and the associated channel regulatory defects remain unknown. Here, we undertook phosphoproteomic analyses to identify and quantify in situ the phosphorylation sites in the NaV1.5 proteins purified from adult WT and failing CaMKIIδc-overexpressing (CaMKIIδc-Tg) mouse ventricles. Of 19 native NaV1.5 phosphorylation sites identified, two C-terminal phosphoserines at positions 1938 and 1989 showed increased phosphorylation in the CaMKIIδc-Tg compared with the WT ventricles. We then tested the hypothesis that phosphorylation at these two sites impairs fibroblast growth factor 13 (FGF13)-dependent regulation of NaV1.5 channel inactivation. Whole-cell voltage-clamp analyses in HEK293 cells demonstrated that FGF13 increases NaV1.5 channel availability and decreases late Na+ current, two effects that were abrogated with NaV1.5 mutants mimicking phosphorylation at both sites. Additional co-immunoprecipitation experiments revealed that FGF13 potentiates the binding of calmodulin to NaV1.5 and that phosphomimetic mutations at both sites decrease the interaction of FGF13 and, consequently, of calmodulin with NaV1.5. Together, we have identified two novel native phosphorylation sites in the C terminus of NaV1.5 that impair FGF13-dependent regulation of channel inactivation and may contribute to CaMKIIδc-dependent arrhythmogenic disorders in failing hearts.
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Affiliation(s)
- Sophie Burel
- From the l'Institut du Thorax, INSERM, CNRS, UNIV Nantes, Nantes 44007, France
| | - Fabien C Coyan
- From the l'Institut du Thorax, INSERM, CNRS, UNIV Nantes, Nantes 44007, France
| | - Maxime Lorenzini
- From the l'Institut du Thorax, INSERM, CNRS, UNIV Nantes, Nantes 44007, France
| | | | - Cheryl F Lichti
- the Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas 77555
| | - Joan H Brown
- the Department of Pharmacology, University of California at San Diego, La Jolla, California 92093-0636, and
| | - Gildas Loussouarn
- From the l'Institut du Thorax, INSERM, CNRS, UNIV Nantes, Nantes 44007, France
| | - Flavien Charpentier
- From the l'Institut du Thorax, INSERM, CNRS, UNIV Nantes, Nantes 44007, France
| | | | - R Reid Townsend
- Internal Medicine, and
- Cell Biology and Physiology, Washington University Medical School, St. Louis, Missouri 63110
| | - Lars S Maier
- the Department of Internal Medicine II, University Heart Center, University Hospital Regensburg, D-93042 Regensburg, Germany
| | - Céline Marionneau
- From the l'Institut du Thorax, INSERM, CNRS, UNIV Nantes, Nantes 44007, France,
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24
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Wang X, Tang H, Wei EQ, Wang Z, Yang J, Yang R, Wang S, Zhang Y, Pitt GS, Zhang H, Wang C. Conditional knockout of Fgf13 in murine hearts increases arrhythmia susceptibility and reveals novel ion channel modulatory roles. J Mol Cell Cardiol 2017; 104:63-74. [PMID: 28119060 DOI: 10.1016/j.yjmcc.2017.01.009] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Revised: 01/13/2017] [Accepted: 01/17/2017] [Indexed: 01/06/2023]
Abstract
The intracellular fibroblast growth factors (iFGF/FHFs) bind directly to cardiac voltage gated Na+ channels, and modulate their function. Mutations that affect iFGF/FHF-Na+ channel interaction are associated with arrhythmia syndromes. Although suspected to modulate other ionic currents, such as Ca2+ channels based on acute knockdown experiments in isolated cardiomyocytes, the in vivo consequences of iFGF/FHF gene ablation on cardiac electrical activity are still unknown. We generated inducible, cardiomyocyte-restricted Fgf13 knockout mice to determine the resultant effects of Fgf13 gene ablation. Patch clamp recordings from ventricular myocytes isolated from Fgf13 knockout mice showed a ~25% reduction in peak Na+ channel current density and a hyperpolarizing shift in steady-state inactivation. Electrocardiograms on Fgf13 knockout mice showed a prolonged QRS duration. The Na+ channel blocker flecainide further prolonged QRS duration and triggered ventricular tachyarrhythmias only in Fgf13 knockout mice, suggesting that arrhythmia vulnerability resulted, at least in part, from a loss of functioning Na+ channels. Consistent with these effects on Na+ channels, action potentials in Fgf13 knockout mice, compared to Cre control mice, exhibited slower upstrokes and reduced amplitude, but unexpectedly had longer durations. We investigated candidate sources of the prolonged action potential durations in myocytes from Fgf13 knockout mice and found a reduction of the transient outward K+ current (Ito). Fgf13 knockout did not alter whole-cell protein levels of Kv4.2 and Kv4.3, the Ito pore-forming subunits, but did decrease Kv4.2 and Kv4.3 at the sarcolemma. No changes were seen in the sustained outward K+ current or voltage-gated Ca2+ current, other candidate contributors to the increased action potential duration. These results implicate that FGF13 is a critical cardiac Na+ channel modulator and Fgf13 knockout mice have increased arrhythmia susceptibility in the setting of Na+ channel blockade. The unanticipated effect on Ito revealed new FGF13 properties and the unexpected lack of an effect on voltage-gated Ca2+ channels highlight potential compensatory changes in vivo not readily revealed with acute Fgf13 knockdown in cultured cardiomyocytes.
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Affiliation(s)
- Xiangchong Wang
- Department of Pharmacology, Hebei Medical University, Shijiazhuang 050017, China; The Key Laboratory of Neural and Vascular Biology, Ministry of Education, China, Shijiazhuang, 050017, China; The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Province, Shijiazhuang 050017, China
| | - He Tang
- Department of Pharmacology, Hebei Medical University, Shijiazhuang 050017, China; The Key Laboratory of Neural and Vascular Biology, Ministry of Education, China, Shijiazhuang, 050017, China; The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Province, Shijiazhuang 050017, China
| | - Eric Q Wei
- Ion Channel Research Unit, Department of Medicine/Cardiology and Pharmacology, Duke University Medical Center, Durham, NC 27710, USA
| | - Zhihua Wang
- Department of Pharmacology, Hebei Medical University, Shijiazhuang 050017, China; The Key Laboratory of Neural and Vascular Biology, Ministry of Education, China, Shijiazhuang, 050017, China; The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Province, Shijiazhuang 050017, China
| | - Jing Yang
- Department of Physiology, Hebei Medical University, Shijiazhuang 050017, China
| | - Rong Yang
- Department of Cardiology, The Second Hospital of Hebei Medical University, Shijiazhuang 050000, China
| | - Sheng Wang
- Department of Physiology, Hebei Medical University, Shijiazhuang 050017, China
| | - Yongjian Zhang
- Department of Pharmacology, Hebei Medical University, Shijiazhuang 050017, China; The Key Laboratory of Neural and Vascular Biology, Ministry of Education, China, Shijiazhuang, 050017, China; The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Province, Shijiazhuang 050017, China
| | - Geoffrey S Pitt
- Ion Channel Research Unit, Department of Medicine/Cardiology and Pharmacology, Duke University Medical Center, Durham, NC 27710, USA
| | - Hailin Zhang
- Department of Pharmacology, Hebei Medical University, Shijiazhuang 050017, China; The Key Laboratory of Neural and Vascular Biology, Ministry of Education, China, Shijiazhuang, 050017, China; The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Province, Shijiazhuang 050017, China.
| | - Chuan Wang
- Department of Pharmacology, Hebei Medical University, Shijiazhuang 050017, China; The Key Laboratory of Neural and Vascular Biology, Ministry of Education, China, Shijiazhuang, 050017, China; The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Province, Shijiazhuang 050017, China.
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