1
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Lahiri SK, Jin F, Zhou Y, Quick AP, Kramm CF, Wang MC, Wehrens XH. Altered myocardial lipid regulation in junctophilin-2-associated familial cardiomyopathies. Life Sci Alliance 2024; 7:e202302330. [PMID: 38438248 PMCID: PMC10912815 DOI: 10.26508/lsa.202302330] [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: 08/22/2023] [Revised: 02/22/2024] [Accepted: 02/23/2024] [Indexed: 03/06/2024] Open
Abstract
Myocardial lipid metabolism is critical to normal heart function, whereas altered lipid regulation has been linked to cardiac diseases including cardiomyopathies. Genetic variants in the JPH2 gene can cause hypertrophic cardiomyopathy (HCM) and, in some cases, dilated cardiomyopathy (DCM). In this study, we tested the hypothesis that JPH2 variants identified in patients with HCM and DCM, respectively, cause distinct alterations in myocardial lipid profiles. Echocardiography revealed clinically significant cardiac dysfunction in both knock-in mouse models of cardiomyopathy. Unbiased myocardial lipidomic analysis demonstrated significantly reduced levels of total unsaturated fatty acids, ceramides, and various phospholipids in both mice with HCM and DCM, suggesting a common metabolic alteration in both models. On the contrary, significantly increased di- and triglycerides, and decreased co-enzyme were only found in mice with HCM. Moreover, mice with DCM uniquely exhibited elevated levels of cholesterol ester. Further in-depth analysis revealed significantly altered metabolites from all the lipid classes with either similar or opposing trends in JPH2 mutant mice with HCM or DCM. Together, these studies revealed, for the first time, unique alterations in the cardiac lipid composition-including distinct increases in neutral lipids and decreases in polar membrane lipids-in mice with HCM and DCM were caused by distinct JPH2 variants. These studies may aid the development of novel biomarkers or therapeutics for these inherited disorders.
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Affiliation(s)
- Satadru K Lahiri
- https://ror.org/02pttbw34 Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX, USA
- https://ror.org/02pttbw34 Department of Integrative Physiology, Baylor College of Medicine, Houston, TX, USA
| | - Feng Jin
- https://ror.org/02pttbw34 Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Yue Zhou
- https://ror.org/02pttbw34 Huffington Center on Aging, Baylor College of Medicine, Houston, TX, USA
| | - Ann P Quick
- https://ror.org/02pttbw34 Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX, USA
- https://ror.org/02pttbw34 Department of Integrative Physiology, Baylor College of Medicine, Houston, TX, USA
| | - Carlos F Kramm
- https://ror.org/02pttbw34 Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX, USA
- https://ror.org/02pttbw34 Department of Integrative Physiology, Baylor College of Medicine, Houston, TX, USA
| | - Meng C Wang
- https://ror.org/02pttbw34 Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- https://ror.org/02pttbw34 Huffington Center on Aging, Baylor College of Medicine, Houston, TX, USA
- https://ror.org/02pttbw34 Howard Hughes Medical Institute, Baylor College of Medicine, Houston, TX, USA
| | - Xander Ht Wehrens
- https://ror.org/02pttbw34 Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX, USA
- https://ror.org/02pttbw34 Department of Integrative Physiology, Baylor College of Medicine, Houston, TX, USA
- https://ror.org/02pttbw34 Department of Medicine, Baylor College of Medicine, Houston, TX, USA
- https://ror.org/02pttbw34 Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
- https://ror.org/02pttbw34 Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
- https://ror.org/02pttbw34 Center for Space Medicine, Baylor College of Medicine, Houston, TX, USA
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2
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Hall DD, Takeshima H, Song LS. Structure, Function, and Regulation of the Junctophilin Family. Annu Rev Physiol 2024; 86:123-147. [PMID: 37931168 PMCID: PMC10922073 DOI: 10.1146/annurev-physiol-042022-014926] [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] [Indexed: 11/08/2023]
Abstract
In both excitable and nonexcitable cells, diverse physiological processes are linked to different calcium microdomains within nanoscale junctions that form between the plasma membrane and endo-sarcoplasmic reticula. It is now appreciated that the junctophilin protein family is responsible for establishing, maintaining, and modulating the structure and function of these junctions. We review foundational findings from more than two decades of research that have uncovered how junctophilin-organized ultrastructural domains regulate evolutionarily conserved biological processes. We discuss what is known about the junctophilin family of proteins. Our goal is to summarize the current knowledge of junctophilin domain structure, function, and regulation and to highlight emerging avenues of research that help our understanding of the transcriptional, translational, and post-translational regulation of this gene family and its roles in health and during disease.
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Affiliation(s)
- Duane D Hall
- Department of Internal Medicine, Division of Cardiovascular Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA; ,
| | - Hiroshi Takeshima
- Department of Biological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
| | - Long-Sheng Song
- Department of Internal Medicine, Division of Cardiovascular Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA; ,
- Department of Biochemistry and Molecular Biology, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA
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3
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Chiang CY, Fan S, Zheng H, Guo W, Zheng Z, Sun Y, Zhong C, Zeng J, Li S, Zhang M, Xiao T, Zheng D. Methylation of KRAS by SETD7 promotes KRAS degradation in non-small cell lung cancer. Cell Rep 2023; 42:113003. [PMID: 37682707 DOI: 10.1016/j.celrep.2023.113003] [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] [Received: 07/19/2021] [Revised: 06/18/2023] [Accepted: 08/02/2023] [Indexed: 09/10/2023] Open
Abstract
Oncogenic KRAS mutations are a key driver for initiation and progression in non-small cell lung cancer (NSCLC). However, how post-translational modifications (PTMs) of KRAS, especially methylation, modify KRAS activity remain largely unclear. Here, we show that SET domain containing histone lysine methyltransferase 7 (SETD7) interacts with KRAS and methylates KRAS at lysines 182 and 184. SETD7-mediated methylation of KRAS leads to degradation of KRAS and attenuation of the RAS/MEK/ERK signaling cascade, endowing SETD7 with a potent tumor-suppressive role in NSCLC, both in vitro and in vivo. Mechanistically, RABGEF1, a ubiquitin E3 ligase of KRAS, is recruited and promotes KRAS degradation in a K182/K184 methylation-dependent manner. Notably, SETD7 is inversely correlated with KRAS at the protein level in clinical NSCLC tissues. Low SETD7 or RABGEF1 expression is associated with poor prognosis in lung adenocarcinoma patients. Altogether, our results define a tumor-suppressive function of SETD7 that operates via modulating KRAS methylation and degradation.
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Affiliation(s)
- Cheng-Yao Chiang
- Guangdong Key Laboratory of Genome Instability and Human Disease Prevention, International Cancer Center, Department of Cell Biology and Genetics, Shenzhen University Medical School, Thoracic Surgery Department of the First Affiliated Hospital, Shenzhen University, Shenzhen 518055, China
| | - Songqing Fan
- Department of Pathology, The Second Xiangya Hospital, Central South University, Changsha, Hunan 410008, China
| | - Hongmei Zheng
- Department of Pathology, The Second Xiangya Hospital, Central South University, Changsha, Hunan 410008, China
| | - Wenjun Guo
- Guangdong Key Laboratory of Genome Instability and Human Disease Prevention, International Cancer Center, Department of Cell Biology and Genetics, Shenzhen University Medical School, Thoracic Surgery Department of the First Affiliated Hospital, Shenzhen University, Shenzhen 518055, China
| | - Zehan Zheng
- Guangdong Key Laboratory of Genome Instability and Human Disease Prevention, International Cancer Center, Department of Cell Biology and Genetics, Shenzhen University Medical School, Thoracic Surgery Department of the First Affiliated Hospital, Shenzhen University, Shenzhen 518055, China
| | - Yihua Sun
- Department of Thoracic Surgery, Fudan University Shanghai Cancer Center, Shanghai 200032, China
| | - Chuanqi Zhong
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China
| | - Juan Zeng
- School of Biomedical Engineering, Guangdong Medical University, Dongguan, Guangdong 523808, China
| | - Shuaihu Li
- Guangdong Key Laboratory of Genome Instability and Human Disease Prevention, International Cancer Center, Department of Cell Biology and Genetics, Shenzhen University Medical School, Thoracic Surgery Department of the First Affiliated Hospital, Shenzhen University, Shenzhen 518055, China
| | - Min Zhang
- Guangdong Key Laboratory of Genome Instability and Human Disease Prevention, International Cancer Center, Department of Cell Biology and Genetics, Shenzhen University Medical School, Thoracic Surgery Department of the First Affiliated Hospital, Shenzhen University, Shenzhen 518055, China
| | - Tian Xiao
- Guangdong Key Laboratory of Genome Instability and Human Disease Prevention, International Cancer Center, Department of Cell Biology and Genetics, Shenzhen University Medical School, Thoracic Surgery Department of the First Affiliated Hospital, Shenzhen University, Shenzhen 518055, China.
| | - Duo Zheng
- Guangdong Key Laboratory of Genome Instability and Human Disease Prevention, International Cancer Center, Department of Cell Biology and Genetics, Shenzhen University Medical School, Thoracic Surgery Department of the First Affiliated Hospital, Shenzhen University, Shenzhen 518055, China.
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4
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Anderson AG, Rogers BB, Loupe JM, Rodriguez-Nunez I, Roberts SC, White LM, Brazell JN, Bunney WE, Bunney BG, Watson SJ, Cochran JN, Myers RM, Rizzardi LF. Single nucleus multiomics identifies ZEB1 and MAFB as candidate regulators of Alzheimer's disease-specific cis-regulatory elements. CELL GENOMICS 2023; 3:100263. [PMID: 36950385 PMCID: PMC10025452 DOI: 10.1016/j.xgen.2023.100263] [Citation(s) in RCA: 22] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 12/06/2022] [Accepted: 01/12/2023] [Indexed: 02/05/2023]
Abstract
Cell type-specific transcriptional differences between brain tissues from donors with Alzheimer's disease (AD) and unaffected controls have been well documented, but few studies have rigorously interrogated the regulatory mechanisms responsible for these alterations. We performed single nucleus multiomics (snRNA-seq plus snATAC-seq) on 105,332 nuclei isolated from cortical tissues from 7 AD and 8 unaffected donors to identify candidate cis-regulatory elements (CREs) involved in AD-associated transcriptional changes. We detected 319,861 significant correlations, or links, between gene expression and cell type-specific transposase accessible regions enriched for active CREs. Among these, 40,831 were unique to AD tissues. Validation experiments confirmed the activity of many regions, including several candidate regulators of APP expression. We identified ZEB1 and MAFB as candidate transcription factors playing important roles in AD-specific gene regulation in neurons and microglia, respectively. Microglia links were globally enriched for heritability of AD risk and previously identified active regulatory regions.
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Affiliation(s)
| | - Brianne B. Rogers
- HudsonAlpha Institute for Biotechnology, Huntsville, AL, USA
- University of Alabama at Birmingham, Birmingham, AL, USA
| | - Jacob M. Loupe
- HudsonAlpha Institute for Biotechnology, Huntsville, AL, USA
| | | | | | - Lauren M. White
- HudsonAlpha Institute for Biotechnology, Huntsville, AL, USA
| | | | - William E. Bunney
- Department of Psychiatry and Human Behavior, College of Medicine, University of California, Irvine, Irvine, CA, USA
| | - Blynn G. Bunney
- Department of Psychiatry and Human Behavior, College of Medicine, University of California, Irvine, Irvine, CA, USA
| | - Stanley J. Watson
- Mental Health Research Institute, University of Michigan, Ann Arbor, MI, USA
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5
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Dixon RE, Trimmer JS. Endoplasmic Reticulum-Plasma Membrane Junctions as Sites of Depolarization-Induced Ca 2+ Signaling in Excitable Cells. Annu Rev Physiol 2023; 85:217-243. [PMID: 36202100 PMCID: PMC9918718 DOI: 10.1146/annurev-physiol-032122-104610] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Membrane contact sites between endoplasmic reticulum (ER) and plasma membrane (PM), or ER-PM junctions, are found in all eukaryotic cells. In excitable cells they play unique roles in organizing diverse forms of Ca2+ signaling as triggered by membrane depolarization. ER-PM junctions underlie crucial physiological processes such as excitation-contraction coupling, smooth muscle contraction and relaxation, and various forms of activity-dependent signaling and plasticity in neurons. In many cases the structure and molecular composition of ER-PM junctions in excitable cells comprise important regulatory feedback loops linking depolarization-induced Ca2+ signaling at these sites to the regulation of membrane potential. Here, we describe recent findings on physiological roles and molecular composition of native ER-PM junctions in excitable cells. We focus on recent studies that provide new insights into canonical forms of depolarization-induced Ca2+ signaling occurring at junctional triads and dyads of striated muscle, as well as the diversity of ER-PM junctions in these cells and in smooth muscle and neurons.
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Affiliation(s)
- Rose E Dixon
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, California, USA;
| | - James S Trimmer
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, California, USA;
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6
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Calcium Handling in Inherited Cardiac Diseases: A Focus on Catecholaminergic Polymorphic Ventricular Tachycardia and Hypertrophic Cardiomyopathy. Int J Mol Sci 2023; 24:ijms24043365. [PMID: 36834774 PMCID: PMC9963263 DOI: 10.3390/ijms24043365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Revised: 02/02/2023] [Accepted: 02/04/2023] [Indexed: 02/10/2023] Open
Abstract
Calcium (Ca2+) is the major mediator of cardiac contractile function. It plays a key role in regulating excitation-contraction coupling and modulating the systolic and diastolic phases. Defective handling of intracellular Ca2+ can cause different types of cardiac dysfunction. Thus, the remodeling of Ca2+ handling has been proposed to be a part of the pathological mechanism leading to electrical and structural heart diseases. Indeed, to ensure appropriate electrical cardiac conduction and contraction, Ca2+ levels are regulated by several Ca2+-related proteins. This review focuses on the genetic etiology of cardiac diseases related to calcium mishandling. We will approach the subject by focalizing on two clinical entities: catecholaminergic polymorphic ventricular tachycardia (CPVT) as a cardiac channelopathy and hypertrophic cardiomyopathy (HCM) as a primary cardiomyopathy. Further, this review will illustrate the fact that despite the genetic and allelic heterogeneity of cardiac defects, calcium-handling perturbations are the common pathophysiological mechanism. The newly identified calcium-related genes and the genetic overlap between the associated heart diseases are also discussed in this review.
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7
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Yu L, Hall DD, Zhao W, Song LS. NMR resonance assignments of the DNA binding domain of mouse Junctophilin-2. BIOMOLECULAR NMR ASSIGNMENTS 2022; 16:273-279. [PMID: 35665900 PMCID: PMC10394741 DOI: 10.1007/s12104-022-10091-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 05/06/2022] [Indexed: 06/15/2023]
Abstract
Junctophilin-2 (JP2) is a critical structural protein in the heart by stabilizing junctional membrane complexes between the plasma membrane and sarcoplasmic reticula responsible for precise Ca2+ regulation. Such complexes are essential for efficient cardiomyocyte contraction and adaptation to altered cardiac workload conditions. Mutations in the JPH2 gene that encodes JP2 are associated with inherited cardiomyopathies and arrhythmias, and disruption of JP2 function is lethal. Interestingly, cardiac stress promotes the proteolytic cleavage of JP2 that triggers the translocation of its N-terminal fragment into the nucleus to repress maladaptive gene transcription. We previously found that the central region of JP2 is responsible for mediating direct DNA binding interactions. Recent structural studies indicate that this region serves as a structural role in the cytosolic form of JP2 by folding into a single continuous α-helix. However, the structural basis of how this DNA-binding domain interacts with DNA is not known. Here, we report the backbone and sidechain assignments of the DNA-binding domain (residues 331-413) of mouse JP2. These assignments reveal that the JP2 DNA binding domain is an intrinsically disordered protein and contains two α-helices located in the C-terminal portion of the protein. Moreover, this protein binds to DNA in a similar manner to that shown previously by electrophoretic mobility shift assays. Therefore, these assignments provide a framework for further structural studies into the interaction of this JP2 domain with DNA for the elucidation of transcriptional regulation of stress-responsive genes as well as its role in the stabilization of junctional membrane complexes.
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Affiliation(s)
- Liping Yu
- Department of Biochemistry and Molecular Biology, Carver College of Medicine, University of Iowa, B291, CBRB, 285 Newton Road, Iowa City, IA, 52242, USA.
- CCOM NMR Core Facility, Carver College of Medicine, University of Iowa, Iowa City, IA, 52242, USA.
| | - Duane D Hall
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, 285 Newton Road, Iowa City, IA, 52242, USA
| | - Weiyang Zhao
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, 285 Newton Road, Iowa City, IA, 52242, USA
| | - Long-Sheng Song
- Department of Biochemistry and Molecular Biology, Carver College of Medicine, University of Iowa, B291, CBRB, 285 Newton Road, Iowa City, IA, 52242, USA.
- Department of Internal Medicine, Carver College of Medicine, University of Iowa, 285 Newton Road, Iowa City, IA, 52242, USA.
- Fraternal Order of Eagles Diabetes Research Center, Carver College of Medicine, University of Iowa, Iowa City, IA, 52242, USA.
- Iowa City Veterans Affairs Medical Center, Iowa City, IA, 52242, USA.
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8
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Rossi D, Pierantozzi E, Amadsun DO, Buonocore S, Rubino EM, Sorrentino V. The Sarcoplasmic Reticulum of Skeletal Muscle Cells: A Labyrinth of Membrane Contact Sites. Biomolecules 2022; 12:488. [PMID: 35454077 PMCID: PMC9026860 DOI: 10.3390/biom12040488] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Revised: 03/14/2022] [Accepted: 03/18/2022] [Indexed: 12/17/2022] Open
Abstract
The sarcoplasmic reticulum of skeletal muscle cells is a highly ordered structure consisting of an intricate network of tubules and cisternae specialized for regulating Ca2+ homeostasis in the context of muscle contraction. The sarcoplasmic reticulum contains several proteins, some of which support Ca2+ storage and release, while others regulate the formation and maintenance of this highly convoluted organelle and mediate the interaction with other components of the muscle fiber. In this review, some of the main issues concerning the biology of the sarcoplasmic reticulum will be described and discussed; particular attention will be addressed to the structure and function of the two domains of the sarcoplasmic reticulum supporting the excitation-contraction coupling and Ca2+-uptake mechanisms.
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Affiliation(s)
- Daniela Rossi
- Department of Molecular and Developmental Medicine, University of Siena, Via Aldo Moro 2, 53100 Siena, Italy; (E.P.); (D.O.A.); (S.B.); (E.M.R.); (V.S.)
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9
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Bang ML, Bogomolovas J, Chen J. Understanding the molecular basis of cardiomyopathy. Am J Physiol Heart Circ Physiol 2022; 322:H181-H233. [PMID: 34797172 PMCID: PMC8759964 DOI: 10.1152/ajpheart.00562.2021] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 11/16/2021] [Accepted: 11/16/2021] [Indexed: 02/03/2023]
Abstract
Inherited cardiomyopathies are a major cause of mortality and morbidity worldwide and can be caused by mutations in a wide range of proteins located in different cellular compartments. The present review is based on Dr. Ju Chen's 2021 Robert M. Berne Distinguished Lectureship of the American Physiological Society Cardiovascular Section, in which he provided an overview of the current knowledge on the cardiomyopathy-associated proteins that have been studied in his laboratory. The review provides a general summary of the proteins in different compartments of cardiomyocytes associated with cardiomyopathies, with specific focus on the proteins that have been studied in Dr. Chen's laboratory.
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Affiliation(s)
- Marie-Louise Bang
- Institute of Genetic and Biomedical Research (IRGB), National Research Council (CNR), Milan Unit, Milan, Italy
- IRCCS Humanitas Research Hospital, Rozzano (Milan), Italy
| | - Julius Bogomolovas
- Division of Cardiovascular Medicine, Department of Medicine Cardiology, University of California, San Diego, La Jolla, California
| | - Ju Chen
- Division of Cardiovascular Medicine, Department of Medicine Cardiology, University of California, San Diego, La Jolla, California
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10
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Hakui H, Kioka H, Miyashita Y, Nishimura S, Matsuoka K, Kato H, Tsukamoto O, Kuramoto Y, Takuwa A, Takahashi Y, Saito S, Ohta K, Asanuma H, Fu HY, Shinomiya H, Yamada N, Ohtani T, Sawa Y, Kitakaze M, Takashima S, Sakata Y, Asano Y. Loss-of-function mutations in the co-chaperone protein BAG5 cause dilated cardiomyopathy requiring heart transplantation. Sci Transl Med 2022; 14:eabf3274. [PMID: 35044787 DOI: 10.1126/scitranslmed.abf3274] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Dilated cardiomyopathy (DCM) is a major cause of heart failure, characterized by ventricular dilatation and systolic dysfunction. Familial DCM is reportedly caused by mutations in more than 50 genes, requiring precise disease stratification based on genetic information. However, the underlying genetic causes of 60 to 80% of familial DCM cases remain unknown. Here, we identified that homozygous truncating mutations in the gene encoding Bcl-2-associated athanogene (BAG) co-chaperone 5 (BAG5) caused inherited DCM in five patients among four unrelated families with complete penetrance. BAG5 acts as a nucleotide exchange factor for heat shock cognate 71 kDa protein (HSC70), promoting adenosine diphosphate release and activating HSC70-mediated protein folding. Bag5 mutant knock-in mice exhibited ventricular dilatation, arrhythmogenicity, and poor prognosis under catecholamine stimulation, recapitulating the human DCM phenotype, and administration of an adeno-associated virus 9 vector carrying the wild-type BAG5 gene could fully ameliorate these DCM phenotypes. Immunocytochemical analysis revealed that BAG5 localized to junctional membrane complexes (JMCs), critical microdomains for calcium handling. Bag5-mutant mouse cardiomyocytes exhibited decreased abundance of functional JMC proteins under catecholamine stimulation, disrupted JMC structure, and calcium handling abnormalities. We also identified heterozygous truncating mutations in three patients with tachycardia-induced cardiomyopathy, a reversible DCM subtype associated with abnormal calcium homeostasis. Our study suggests that loss-of-function mutations in BAG5 can cause DCM, that BAG5 may be a target for genetic testing in cases of DCM, and that gene therapy may potentially be a treatment for this disease.
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Affiliation(s)
- Hideyuki Hakui
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871, Japan
| | - Hidetaka Kioka
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871, Japan
| | - Yohei Miyashita
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871, Japan
| | - Shunsuke Nishimura
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871, Japan
| | - Ken Matsuoka
- Department of Medical Biochemistry, Osaka University Graduate School of Frontier Biosciences, Suita, Osaka 565-0871, Japan
| | - Hisakazu Kato
- Department of Medical Biochemistry, Osaka University Graduate School of Frontier Biosciences, Suita, Osaka 565-0871, Japan
| | - Osamu Tsukamoto
- Department of Medical Biochemistry, Osaka University Graduate School of Frontier Biosciences, Suita, Osaka 565-0871, Japan
| | - Yuki Kuramoto
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871, Japan
| | - Ayako Takuwa
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871, Japan
| | - Yusuke Takahashi
- Department of Molecular Pharmacology, National Cerebral and Cardiovascular Center, Suita, Osaka 564-8565, Japan
| | - Shigeyoshi Saito
- Department of Medical Physics and Engineering, Division of Health Sciences, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871, Japan.,Department of Biomedical Imaging, National Cerebral and Cardiovascular Center, Suita, Osaka 564-8565, Japan
| | - Kunio Ohta
- Department of Pediatrics, School of Medicine, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Ishikawa 920-8640, Japan
| | - Hiroshi Asanuma
- Department of Internal Medicine, Meiji University of Integrative Medicine, Nantan, Kyoto 629-0392, Japan
| | - Hai Ying Fu
- Department of Clinical Medicine and Development, National Cerebral and Cardiovascular Center, Suita, Osaka 564-8565, Japan
| | - Haruki Shinomiya
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871, Japan
| | - Noriaki Yamada
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871, Japan
| | - Tomohito Ohtani
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871, Japan
| | - Yoshiki Sawa
- Department of Cardiovascular Surgery, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871, Japan
| | - Masafumi Kitakaze
- Department of Clinical Medicine and Development, National Cerebral and Cardiovascular Center, Suita, Osaka 564-8565, Japan
| | - Seiji Takashima
- Department of Medical Biochemistry, Osaka University Graduate School of Frontier Biosciences, Suita, Osaka 565-0871, Japan
| | - Yasushi Sakata
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871, Japan
| | - Yoshihiro Asano
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871, Japan
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11
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Abstract
Junctophilins (JPHs) comprise a family of structural proteins that connect the plasma membrane to intracellular organelles such as the endo/sarcoplasmic reticulum. Tethering of these membrane structures results in the formation of highly organized subcellular junctions that play important signaling roles in all excitable cell types. There are four JPH isoforms, expressed primarily in muscle and neuronal cell types. Each JPH protein consists of 6 'membrane occupation and recognition nexus' (MORN) motifs, a joining region connecting these to another set of 2 MORN motifs, a putative alpha-helical region, a divergent region exhibiting low homology between JPH isoforms, and a carboxy-terminal transmembrane region anchoring into the ER/SR membrane. JPH isoforms play essential roles in developing and maintaining subcellular membrane junctions. Conversely, inherited mutations in JPH2 cause hypertrophic or dilated cardiomyopathy, while trinucleotide expansions in the JPH3 gene cause Huntington Disease-Like 2. Loss of JPH1 protein levels can cause skeletal myopathy, while loss of cardiac JPH2 levels causes heart failure and atrial fibrillation, among other disease. This review will provide a comprehensive overview of the JPH gene family, phylogeny, and evolutionary analysis of JPH genes and other MORN domain proteins. JPH biogenesis, membrane tethering, and binding partners will be discussed, as well as functional roles of JPH isoforms in excitable cells. Finally, potential roles of JPH isoform deficits in human disease pathogenesis will be reviewed.
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Affiliation(s)
- Stephan E Lehnart
- Cellular Biophysics and Translational Cardiology Section, Heart Research Center Göttingen, University Medical Center Göttingen, Department of Cardiology and Pneumology, Georg-August University Göttingen, Göttingen, Germany.,Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Germany.,DZHK (German Centre for Cardiovascular Research), partner site Göttingen, Germany
| | - Xander H T Wehrens
- Cardiovascular Research Institute, Baylor College of Medicine, Houston, Texas, United States; Departments of Molecular Physiology and Biophysics, Medicine (Cardiology), Pediatrics (Cardiology), Neuroscience, and Center for Space Medicine, Baylor College of Medicine, Houston, Texas, United States
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12
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Perni S. The Builders of the Junction: Roles of Junctophilin1 and Junctophilin2 in the Assembly of the Sarcoplasmic Reticulum–Plasma Membrane Junctions in Striated Muscle. Biomolecules 2022; 12:biom12010109. [PMID: 35053257 PMCID: PMC8774113 DOI: 10.3390/biom12010109] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 01/06/2022] [Accepted: 01/07/2022] [Indexed: 02/06/2023] Open
Abstract
Contraction of striated muscle is triggered by a massive release of calcium from the sarcoplasmic reticulum (SR) into the cytoplasm. This intracellular calcium release is initiated by membrane depolarization, which is sensed by voltage-gated calcium channels CaV1.1 (in skeletal muscle) and CaV1.2 (in cardiac muscle) in the plasma membrane (PM), which in turn activate the calcium-releasing channel ryanodine receptor (RyR) embedded in the SR membrane. This cross-communication between channels in the PM and in the SR happens at specialized regions, the SR-PM junctions, where these two compartments come in close proximity. Junctophilin1 and Junctophilin2 are responsible for the formation and stabilization of SR-PM junctions in striated muscle and actively participate in the recruitment of the two essential players in intracellular calcium release, CaV and RyR. This short review focuses on the roles of junctophilins1 and 2 in the formation and organization of SR-PM junctions in skeletal and cardiac muscle and on the functional consequences of the absence or malfunction of these proteins in striated muscle in light of recently published data and recent advancements in protein structure prediction.
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Affiliation(s)
- Stefano Perni
- Department of Physiology and Biophysics, Anschutz Medical Campus, University of Colorado, Aurora, CO 80045, USA
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13
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Piggott CA, Wu Z, Nurrish S, Xu S, Kaplan JM, Chisholm AD, Jin Y. Caenorhabditis elegans junctophilin has tissue-specific functions and regulates neurotransmission with extended-synaptotagmin. Genetics 2021; 218:iyab063. [PMID: 33871019 PMCID: PMC8864756 DOI: 10.1093/genetics/iyab063] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Accepted: 04/12/2021] [Indexed: 02/06/2023] Open
Abstract
The junctophilin family of proteins tether together plasma membrane (PM) and endoplasmic reticulum (ER) membranes, and couple PM- and ER-localized calcium channels. Understanding in vivo functions of junctophilins is of great interest for dissecting the physiological roles of ER-PM contact sites. Here, we show that the sole Caenorhabditis elegans junctophilin JPH-1 localizes to discrete membrane contact sites in neurons and muscles and has important tissue-specific functions. jph-1 null mutants display slow growth and development due to weaker contraction of pharyngeal muscles, leading to reduced feeding. In the body wall muscle, JPH-1 colocalizes with the PM-localized EGL-19 voltage-gated calcium channel and ER-localized UNC-68 RyR calcium channel, and is required for animal movement. In neurons, JPH-1 colocalizes with the membrane contact site protein Extended-SYnaptoTagmin 2 (ESYT-2) in the soma, and is present near presynaptic release sites. Interestingly, jph-1 and esyt-2 null mutants display mutual suppression in their response to aldicarb, suggesting that JPH-1 and ESYT-2 have antagonistic roles in neuromuscular synaptic transmission. Additionally, we find an unexpected cell nonautonomous effect of jph-1 in axon regrowth after injury. Genetic double mutant analysis suggests that jph-1 functions in overlapping pathways with two PM-localized voltage-gated calcium channels, egl-19 and unc-2, and with unc-68 for animal health and development. Finally, we show that jph-1 regulates the colocalization of EGL-19 and UNC-68 and that unc-68 is required for JPH-1 localization to ER-PM puncta. Our data demonstrate important roles for junctophilin in cellular physiology, and also provide insights into how junctophilin functions together with other calcium channels in vivo.
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Affiliation(s)
- Christopher A Piggott
- Section of Neurobiology, Division of Biological Sciences, University of California San Diego, La Jolla, CA 92093, USA
| | - Zilu Wu
- Section of Neurobiology, Division of Biological Sciences, University of California San Diego, La Jolla, CA 92093, USA
| | - Stephen Nurrish
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Suhong Xu
- Section of Neurobiology, Division of Biological Sciences, University of California San Diego, La Jolla, CA 92093, USA
| | - Joshua M Kaplan
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Andrew D Chisholm
- Section of Neurobiology, Division of Biological Sciences, University of California San Diego, La Jolla, CA 92093, USA
| | - Yishi Jin
- Section of Neurobiology, Division of Biological Sciences, University of California San Diego, La Jolla, CA 92093, USA
- Department of Cellular and Molecular Medicine, School of Medicine, University of California San Diego, La Jolla, CA 92093, USA
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14
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Targeting JP2: A New Treatment for Pulmonary Hypertension. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2021; 2021:2003446. [PMID: 34394822 PMCID: PMC8363443 DOI: 10.1155/2021/2003446] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 07/21/2021] [Accepted: 07/27/2021] [Indexed: 12/16/2022]
Abstract
Pulmonary hypertension (PH) is a disease with a complex etiology and high mortality rate. Abnormal pulmonary vasoconstriction and pulmonary vascular remodeling lead to an increase in mean pulmonary arterial blood pressure for which, and there is currently no cure. Junctophilin-2 (JP2) is beneficial for the assembly of junctional membrane complexes, the structural basis for excitation-contraction coupling that tethers the plasma membrane to the sarcoplasmic reticulum/endoplasmic reticulum and is involved in maintaining intracellular calcium concentration homeostasis and normal muscle contraction function. Recent studies have shown that JP2 maintains normal contraction and relaxation of vascular smooth muscle. In some experimental studies of drug treatments for PH, JP2 expression was increased, which improved pulmonary vascular remodeling and right ventricular function. Based on JP2 research to date, this paper summarizes the current understanding of JP2 protein structure, function, and related heart diseases and mechanisms and analyzes the feasibility and possible therapeutic strategies for targeting JP2 in PH.
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15
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Piggott CA, Jin Y. Junctophilins: Key Membrane Tethers in Muscles and Neurons. Front Mol Neurosci 2021; 14:709390. [PMID: 34305529 PMCID: PMC8295595 DOI: 10.3389/fnmol.2021.709390] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Accepted: 06/15/2021] [Indexed: 12/26/2022] Open
Abstract
Contacts between the endoplasmic reticulum (ER) and plasma membrane (PM) contain specialized tethering proteins that bind both ER and PM membranes. In excitable cells, ER–PM contacts play an important role in calcium signaling and transferring lipids. Junctophilins are a conserved family of ER–PM tethering proteins. They are predominantly expressed in muscles and neurons and known to simultaneously bind both ER- and PM-localized ion channels. Since their discovery two decades ago, functional studies using junctophilin-deficient animals have provided a deep understanding of their roles in muscles and neurons, including excitation-contraction coupling, store-operated calcium entry (SOCE), and afterhyperpolarization (AHP). In this review, we highlight key findings from mouse, fly, and worm that support evolutionary conservation of junctophilins.
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Affiliation(s)
- Christopher A Piggott
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, San Diego, CA, United States
| | - Yishi Jin
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, San Diego, CA, United States
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16
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Urkasemsin G, Pongpanich M, Sariya L, Kongcharoen A, Buddhirongawatr R, Rungarunlert S, Ferreira JN, Chetruengchai W, Phokaew C, Srichomthong C, Shotelersuk V. Whole genome sequencing identifies a homozygous nonsense mutation in the JPH2 gene in Shih Tzu dogs with progressive retinal atrophy. Anim Genet 2021; 52:714-719. [PMID: 34231238 DOI: 10.1111/age.13118] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/24/2021] [Indexed: 11/28/2022]
Abstract
Progressive retinal atrophy (PRA), common autosomal recessive disorder affecting several dog breeds including Shih Tzu, is characterized by degeneration of photoreceptors leading to blindness. To identify PRA genetic variants, three affected and 15 unaffected Shih Tzu and 20 non-Shih Tzu were recruited. Dogs underwent ophthalmologic examination and electroretinography, revealing hallmark retina pathological changes and an abnormal electroretinography in all affected dogs but not in unaffected dogs. WGS was performed. Non-synonymous homozygous variants were searched in coding regions of genes involved in retinal diseases/development; the criterion was that variants should only be present in affected dogs and should be absent in both unaffected and 46 genomes of dogs (from an available evolutionary database). Only one out of the 109 identified variants is predicted to harbor a high-impact consequence, a nonsense c.452A>C (p.L151X) in the JPH2 gene. The genotype of JPH2 variant in all 38 dogs was determined with Sanger sequencing. All three affected dogs, but none of the 35 unaffected, were homozygous for the nonsense variant. JPH2 has been previously found to be expressed in several excitable cells/tissues including retina photoreceptors. Hence, JPH2 is a candidate gene for PRA in Shih Tzu.
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Affiliation(s)
- G Urkasemsin
- Department of Preclinic and Applied Animal Science, Faculty of Veterinary Science, Mahidol University, Nakhon Pathom, 73170, Thailand
| | - M Pongpanich
- Department of Mathematics and Computer Science, Faculty of Science, Chulalongkorn University, Bangkok, 10330, Thailand.,Age-related Inflammation and Degeneration Research Unit, Chulalongkorn University, Bangkok, 10330, Thailand
| | - L Sariya
- The Monitoring and Surveillance Center for Zoonotic Diseases in Wildlife and Exotic Animals, Faculty of Veterinary Science, Mahidol University, Nakhon Pathom, 73170, Thailand
| | - A Kongcharoen
- Prasu-Arthorn Animal Hospital, Faculty of Veterinary Science, Mahidol University, Nakhon Pathom, 73170, Thailand
| | - R Buddhirongawatr
- Department of Clinical Sciences and Public Health, Faculty of Veterinary Science, Mahidol University, Nakhon Pathom, 73170, Thailand
| | - S Rungarunlert
- Department of Preclinic and Applied Animal Science, Faculty of Veterinary Science, Mahidol University, Nakhon Pathom, 73170, Thailand
| | - J N Ferreira
- Exocrine Gland Biology and Regeneration Research Group, Faculty of Dentistry, Chulalongkorn University, Bangkok, 10330, Thailand
| | - W Chetruengchai
- Department of Pediatrics, Faculty of Medicine, Center of Excellence for Medical Genomics, Medical Genomics Cluster, Chulalongkorn University, Bangkok, 10330, Thailand.,Excellence Center for Genomics and Precision Medicine, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, 10330, Thailand
| | - C Phokaew
- Department of Pediatrics, Faculty of Medicine, Center of Excellence for Medical Genomics, Medical Genomics Cluster, Chulalongkorn University, Bangkok, 10330, Thailand.,Excellence Center for Genomics and Precision Medicine, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, 10330, Thailand
| | - C Srichomthong
- Department of Pediatrics, Faculty of Medicine, Center of Excellence for Medical Genomics, Medical Genomics Cluster, Chulalongkorn University, Bangkok, 10330, Thailand.,Excellence Center for Genomics and Precision Medicine, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, 10330, Thailand
| | - V Shotelersuk
- Department of Pediatrics, Faculty of Medicine, Center of Excellence for Medical Genomics, Medical Genomics Cluster, Chulalongkorn University, Bangkok, 10330, Thailand.,Excellence Center for Genomics and Precision Medicine, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, 10330, Thailand
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17
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Allelic and phenotypic heterogeneity in Junctophillin-3 related neurodevelopmental and movement disorders. Eur J Hum Genet 2021; 29:1027-1031. [PMID: 33824468 PMCID: PMC8187377 DOI: 10.1038/s41431-021-00866-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 02/22/2021] [Accepted: 03/10/2021] [Indexed: 12/28/2022] Open
Abstract
Junctophilin-3 belongs to a triprotein junctional complex implicated in the regulation of neuronal excitability and involved in the formation of junctional membrane structures between voltage-gated ion channels and endoplasmic (ryanodine) reticular receptors. A monoallelic trinucleotide repeat expansion located within the junctophilin-3 gene (JPH3) has been implicated in a rare autosomal dominant (AD) late-onset (and progressive) disorder clinically resembling Huntington disease (HD), and known as HD-like 2 (HDL2; MIM# 606438). Although the exact molecular mechanisms underlying HDL2 has not yet been fully elucidated, toxic gain-of-function of the aberrant transcript (containing the trinucleotide repeat) and loss of expression of (full-length) junctophilin-3 have both been implicated in HDL2 pathophysiology. In this study, we identified by whole exome sequencing (WES) a JPH3 homozygous truncating variant [NM_020655.4: c.17405dup; p.(Val581Argfs*137)]. in a female individual affected with genetically undetermined neurodevelopmental anomalies (including delayed motor milestones, abnormal social communication, language difficulties and borderline cognitive impairment) and paroxysmal attacks of dystonia since her early infancy. Our study expands the JPH3-associated mutational spectrum and clinical phenotypes, implicating the loss of Junctophilin-3 in heterogeneous neurodevelopmental phenotypes and early-onset paroxysmal movement disorders.
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18
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Perni S, Beam K. Neuronal junctophilins recruit specific Ca V and RyR isoforms to ER-PM junctions and functionally alter Ca V2.1 and Ca V2.2. eLife 2021; 10:64249. [PMID: 33769283 PMCID: PMC8046434 DOI: 10.7554/elife.64249] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 03/19/2021] [Indexed: 12/15/2022] Open
Abstract
Junctions between the endoplasmic reticulum and plasma membrane that are induced by the neuronal junctophilins are of demonstrated importance, but their molecular architecture is still poorly understood and challenging to address in neurons. This is due to the small size of the junctions and the multiple isoforms of candidate junctional proteins in different brain areas. Using colocalization of tagged proteins expressed in tsA201 cells, and electrophysiology, we compared the interactions of JPH3 and JPH4 with different calcium channels. We found that JPH3 and JPH4 caused junctional accumulation of all the tested high-voltage-activated CaV isoforms, but not a low-voltage-activated CaV. Also, JPH3 and JPH4 noticeably modify CaV2.1 and CaV2.2 inactivation rate. RyR3 moderately colocalized at junctions with JPH4, whereas RyR1 and RyR2 did not. By contrast, RyR1 and RyR3 strongly colocalized with JPH3, and RyR2 moderately. Likely contributing to this difference, JPH3 binds to cytoplasmic domain constructs of RyR1 and RyR3, but not of RyR2.
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Affiliation(s)
- Stefano Perni
- Department of Physiology and Biophysics, Anschutz Medical Campus, University of Colorado, Aurora, United States
| | - Kurt Beam
- Department of Physiology and Biophysics, Anschutz Medical Campus, University of Colorado, Aurora, United States
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19
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Hewlett B, Singh NP, Vannier C, Galli T. ER-PM Contact Sites - SNARING Actors in Emerging Functions. Front Cell Dev Biol 2021; 9:635518. [PMID: 33681218 PMCID: PMC7928305 DOI: 10.3389/fcell.2021.635518] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 01/21/2021] [Indexed: 11/13/2022] Open
Abstract
The compartmentalisation achieved by confining cytoplasm into membrane-enclosed organelles in eukaryotic cells is essential for maintaining vital functions including ATP production, synthetic and degradative pathways. While intracellular organelles are highly specialised in these functions, the restricting membranes also impede exchange of molecules responsible for the synchronised and responsive cellular activities. The initial identification of contact sites between the ER and plasma membrane (PM) provided a potential candidate structure for communication between organelles without mixing by fusion. Over the past decades, research has revealed a far broader picture of the events. Membrane contact sites (MCSs) have been recognized as increasingly important actors in cell differentiation, plasticity and maintenance, and, upon dysfunction, responsible for pathological conditions such as cancer and neurodegenerative diseases. Present in multiple organelles and cell types, MCSs promote transport of lipids and Ca2+ homoeostasis, with a range of associated protein families. Interestingly, each MCS displays a unique molecular signature, adapted to organelle functions. This review will explore the literature describing the molecular components and interactions taking place at ER-PM contact sites, their functions, and implications in eukaryotic cells, particularly neurons, with emphasis on lipid transfer proteins and emerging function of SNAREs.
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Affiliation(s)
- Bailey Hewlett
- INSERM U1266, Institut de Psychiatrie et Neurosciences de Paris, Université de Paris, Paris, France
| | - Neha Pratap Singh
- INSERM U1266, Institut de Psychiatrie et Neurosciences de Paris, Université de Paris, Paris, France
| | - Christian Vannier
- INSERM U1266, Institut de Psychiatrie et Neurosciences de Paris, Université de Paris, Paris, France
| | - Thierry Galli
- INSERM U1266, Institut de Psychiatrie et Neurosciences de Paris, Université de Paris, Paris, France.,GHU PARIS Psychiatrie and Neurosciences, Paris, France
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20
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Mechanisms underlying pathological Ca 2+ handling in diseases of the heart. Pflugers Arch 2021; 473:331-347. [PMID: 33399957 PMCID: PMC10070045 DOI: 10.1007/s00424-020-02504-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 12/01/2020] [Accepted: 12/09/2020] [Indexed: 02/07/2023]
Abstract
Cardiomyocyte contraction relies on precisely regulated intracellular Ca2+ signaling through various Ca2+ channels and transporters. In this article, we will review the physiological regulation of Ca2+ handling and its role in maintaining normal cardiac rhythm and contractility. We discuss how inherited variants or acquired defects in Ca2+ channel subunits contribute to the development or progression of diseases of the heart. Moreover, we highlight recent insights into the role of protein phosphatase subunits and striated muscle preferentially expressed protein kinase (SPEG) in atrial fibrillation, heart failure, and cardiomyopathies. Finally, this review summarizes current drug therapies and new advances in genome editing as therapeutic strategies for the cardiac diseases caused by aberrant intracellular Ca2+ signaling.
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21
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Luo T, Li L, Peng Y, Xie R, Yan N, Fan H, Zhang Q. The MORN domain of Junctophilin2 regulates functional interactions with small-conductance Ca 2+ -activated potassium channel subtype2 (SK2). Biofactors 2021; 47:69-79. [PMID: 31904168 DOI: 10.1002/biof.1608] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 12/17/2019] [Indexed: 01/15/2023]
Abstract
Small-conductance Ca2+ -activated K+ channel subtype2 (SK2) are stable macromolecular complexes that regulate myocardial excitability and Ca2+ homeostasis. Junctophilin-2 (JP2) is a membrane-binding protein, which provides functional crosstalk by physically linking with the cell-surface and intracellular ion channels. We previously demonstrated that the MORN domain of JP2 interacts with SK2 channels. However, the roles of the JP2 MORN domain in regulating the precise subcellular localization and molecular modulation of SK2 have not yet been incompletely understood. In the present study, in vitro and in vivo assays were used to confirm the physical interactions between the SK2 channel and JP2 in H9c2 and HEK293 cells, with a concentration on the association between the C-terminus of SK2 channels and the MORN domain of JP2. Furthermore, the membrane expression of SK2 were found to be significantly impaired by the mutation or knockdown of JP2. Using immunofluorescence staining along with Golgi/early endosome markers, we studied the mechanisms of JP2-regulated SK2 membrane trafficking, which indicates that the JP2 MORN domain is probably necessary for the retrograde trafficking of SK2 channels. The functional study demonstrates that whole cell SK2 current densities recorded from the HEK293 cells co-expressing the JP2-MORN domain with SK2 were significantly augmented, compared with cells expressing SK2 alone. Our findings suggest that the MORN domain of JP2 directly modulates SK2 channel current amplitude and trafficking, through its interaction with an overlapping region of the JP2 MORN domain on the SK2 C-terminus.
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Affiliation(s)
- Tianxia Luo
- Department of Physiology, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, China
| | - Liren Li
- Department of Physiology, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, China
| | - Yanghao Peng
- Department of Physiology, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, China
| | - Rongrong Xie
- Department of Physiology, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, China
| | - Ningning Yan
- Department of Physiology, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, China
| | - Hongkun Fan
- Department of Physiology, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, China
| | - Qian Zhang
- Department of Physiology, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, China
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22
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Chen X, Li Y, Luo J, Hou N. Molecular Mechanism of Hippo-YAP1/TAZ Pathway in Heart Development, Disease, and Regeneration. Front Physiol 2020; 11:389. [PMID: 32390875 PMCID: PMC7191303 DOI: 10.3389/fphys.2020.00389] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 04/01/2020] [Indexed: 01/20/2023] Open
Abstract
The Hippo-YAP1/TAZ pathway is a highly conserved central mechanism that controls organ size through the regulation of cell proliferation and other physical attributes of cells. The transcriptional factors Yes-associated protein 1 (YAP1) and PDZ-binding motif (TAZ) act as downstream effectors of the Hippo pathway, and their subcellular location and transcriptional activities are affected by multiple post-translational modifications (PTMs). Studies have conclusively demonstrated a pivotal role of the Hippo-YAP1/TAZ pathway in cardiac development, disease, and regeneration. Targeted therapeutics for the YAP1/TAZ could be an effective treatment option for cardiac regeneration and disease. This review article provides an overview of the Hippo-YAP1/TAZ pathway and the increasing impact of PTMs in fine-tuning YAP1/TAZ activation; in addition, we discuss the potential contributions of the Hippo-YAP1/TAZ pathway in cardiac development, disease, and regeneration.
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Affiliation(s)
- Xiaoqing Chen
- Key Laboratory of Molecular Target & Clinical Pharmacology, School of Pharmaceutical Sciences and the Fifth Affiliated Hospital, Guangzhou Medical University, Guangzhou, China.,Guangzhou Institute of Cardiovascular Disease, Guangzhou Key Laboratory of Cardiovascular Disease, and The Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Yilang Li
- Key Laboratory of Molecular Target & Clinical Pharmacology, School of Pharmaceutical Sciences and the Fifth Affiliated Hospital, Guangzhou Medical University, Guangzhou, China.,Guangzhou Institute of Cardiovascular Disease, Guangzhou Key Laboratory of Cardiovascular Disease, and The Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Jiandong Luo
- Key Laboratory of Molecular Target & Clinical Pharmacology, School of Pharmaceutical Sciences and the Fifth Affiliated Hospital, Guangzhou Medical University, Guangzhou, China.,Guangzhou Institute of Cardiovascular Disease, Guangzhou Key Laboratory of Cardiovascular Disease, and The Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Ning Hou
- Key Laboratory of Molecular Target & Clinical Pharmacology, School of Pharmaceutical Sciences and the Fifth Affiliated Hospital, Guangzhou Medical University, Guangzhou, China.,Guangzhou Institute of Cardiovascular Disease, Guangzhou Key Laboratory of Cardiovascular Disease, and The Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
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23
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Mackrill JJ, Shiels HA. Evolution of Excitation-Contraction Coupling. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1131:281-320. [DOI: 10.1007/978-3-030-12457-1_12] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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24
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Chan BYH, Roczkowsky A, Cho WJ, Poirier M, Lee TYT, Mahmud Z, Schulz R. Junctophilin-2 is a target of matrix metalloproteinase-2 in myocardial ischemia-reperfusion injury. Basic Res Cardiol 2019; 114:42. [PMID: 31506724 DOI: 10.1007/s00395-019-0749-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Accepted: 09/02/2019] [Indexed: 11/30/2022]
Abstract
Junctophilin-2 is a structural membrane protein that tethers T-tubules to the sarcoplasmic reticulum to allow for coordinated calcium-induced calcium release in cardiomyocytes. Defective excitation-contraction coupling in myocardial ischemia-reperfusion (IR) injury is associated with junctophilin-2 proteolysis. However, it remains unclear whether preventing junctophilin-2 proteolysis improves the recovery of cardiac contractile dysfunction in IR injury. Matrix metalloproteinase-2 (MMP-2) is a zinc and calcium-dependent protease that is activated by oxidative stress in myocardial IR injury and cleaves both intracellular and extracellular substrates. To determine whether junctophilin-2 is targeted by MMP-2, isolated rat hearts were perfused in working mode aerobically or subjected to IR injury with the selective MMP inhibitor ARP-100. IR injury impaired the recovery of cardiac contractile function which was associated with increased degradation of junctophilin-2 and damaged cardiac dyads. In IR hearts, ARP-100 improved the recovery of cardiac contractile function, attenuated junctophilin-2 proteolysis, and prevented ultrastructural damage to the dyad. MMP-2 was co-localized with junctophilin-2 in aerobic and IR hearts by immunoprecipitation and immunohistochemistry. In situ zymography showed that MMP activity was localized to the Z-disc and sarcomere in aerobic hearts and accumulated at sites where the striated JPH-2 staining was disrupted in IR hearts. In vitro proteolysis assays determined that junctophilin-2 is susceptible to proteolysis by MMP-2 and in silico analysis predicted multiple MMP-2 cleavage sites between the membrane occupation and recognition nexus repeats and within the divergent region of junctophilin-2. Degradation of junctophilin-2 by MMP-2 is an early consequence of myocardial IR injury which may initiate a cascade of sequelae leading to impaired contractile function.
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Affiliation(s)
- Brandon Y H Chan
- Departments of Pediatrics and Pharmacology, Mazankowski Alberta Heart Institute, 462 Heritage Medical Research Centre, University of Alberta, Edmonton, AB, T6G 2S2, Canada
| | - Andrej Roczkowsky
- Departments of Pediatrics and Pharmacology, Mazankowski Alberta Heart Institute, 462 Heritage Medical Research Centre, University of Alberta, Edmonton, AB, T6G 2S2, Canada
| | - Woo Jung Cho
- Faculty of Medicine and Dentistry Cell Imaging Centre, University of Alberta, Edmonton, AB, Canada
| | - Mathieu Poirier
- Departments of Pediatrics and Pharmacology, Mazankowski Alberta Heart Institute, 462 Heritage Medical Research Centre, University of Alberta, Edmonton, AB, T6G 2S2, Canada
| | - Tim Y T Lee
- Departments of Pediatrics and Pharmacology, Mazankowski Alberta Heart Institute, 462 Heritage Medical Research Centre, University of Alberta, Edmonton, AB, T6G 2S2, Canada
| | - Zabed Mahmud
- Department of Biochemistry, University of Alberta, Edmonton, AB, Canada
| | - Richard Schulz
- Departments of Pediatrics and Pharmacology, Mazankowski Alberta Heart Institute, 462 Heritage Medical Research Centre, University of Alberta, Edmonton, AB, T6G 2S2, Canada.
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25
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Molecular determinants of homo- and heteromeric interactions of Junctophilin-1 at triads in adult skeletal muscle fibers. Proc Natl Acad Sci U S A 2019; 116:15716-15724. [PMID: 31315980 DOI: 10.1073/pnas.1820980116] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In adult skeletal muscles, 2 junctophilin isoforms (JPH1 and JPH2) tether the sarcoplasmic reticulum (SR) to transverse tubule (T-tubule) membranes, generating stable membrane contact sites known as triads. JPHs are anchored to the membrane of the SR by a C-terminal transmembrane domain (TMD) and bind the T-tubule membrane through their cytosolic N-terminal region, which contains 8 lipid-binding (MORN) motifs. By combining expression of GFP-JPH1 deletion mutants in skeletal muscle fibers with in vitro biochemical experiments, we investigated the molecular determinants of JPH1 recruitment at triads in adult skeletal muscle fibers. We found that MORN motifs bind PI(4,5)P2 in the sarcolemma, but do not mediate the selective localization of JPH1 at the T-tubule compartment of triads. On the contrary, fusion proteins containing only the TMD of JPH1 were able to localize at the junctional SR compartment of the triad. Bimolecular fluorescence complementation experiments indicated that the TMD of JPH1 can form dimers, suggesting that the observed localization at triads may result from dimerization with the TMDs of resident JPH1. A second domain, capable of mediating homo- and heterodimeric interactions between JPH1 and JPH2 was identified in the cytosolic region. FRAP experiments revealed that removal of either one of these 2 domains in JPH1 decreases the association of the resulting mutant proteins with triads. Altogether, these results suggest that the ability to establish homo- and heterodimeric interactions with resident JPHs may support the recruitment and stability of newly synthesized JPHs at triads in adult skeletal muscle fibers.
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Jiang J, Tang M, Huang Z, Chen L. Junctophilins emerge as novel therapeutic targets. J Cell Physiol 2019; 234:16933-16943. [DOI: 10.1002/jcp.28405] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 01/25/2019] [Accepted: 01/30/2019] [Indexed: 12/24/2022]
Affiliation(s)
- Jinyong Jiang
- Institute of Pharmacy and Pharmacology, Learning Key Laboratory for Pharmacoproteomics, Hunan Province Cooperative Innovation Center for Molecular Target New Drugs Study University of South China Hengyang China
| | - Mingzhu Tang
- Institute of Pharmacy and Pharmacology, Learning Key Laboratory for Pharmacoproteomics, Hunan Province Cooperative Innovation Center for Molecular Target New Drugs Study University of South China Hengyang China
| | - Zhen Huang
- Institute of Pharmacy and Pharmacology, Learning Key Laboratory for Pharmacoproteomics, Hunan Province Cooperative Innovation Center for Molecular Target New Drugs Study University of South China Hengyang China
| | - Linxi Chen
- Institute of Pharmacy and Pharmacology, Learning Key Laboratory for Pharmacoproteomics, Hunan Province Cooperative Innovation Center for Molecular Target New Drugs Study University of South China Hengyang China
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Biological processes and signal transduction pathways regulated by the protein methyltransferase SETD7 and their significance in cancer. Signal Transduct Target Ther 2018; 3:19. [PMID: 30013796 PMCID: PMC6043541 DOI: 10.1038/s41392-018-0017-6] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2017] [Revised: 02/05/2018] [Accepted: 03/21/2018] [Indexed: 02/07/2023] Open
Abstract
Protein methyltransferases have been shown to methylate histone and non-histone proteins, leading to regulation of several biological processes that control cell homeostasis. Over the past few years, the histone-lysine N-methyltransferase SETD7 (SETD7; also known as SET7/9, KIAA1717, KMT7, SET7, SET9) has emerged as an important regulator of at least 30 non-histone proteins and a potential target for the treatment of several human diseases. This review discusses current knowledge of the structure and subcellular localization of SETD7, as well as its function as a histone and non-histone methyltransferase. This work also underlines the putative contribution of SETD7 to the regulation of gene expression, control of cell proliferation, differentiation and endoplasmic reticulum stress, which indicate that SETD7 is a candidate for novel targeted therapies with the aim of either stimulating or inhibiting its activity, depending on the cell signaling context.
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Kv2 potassium channels form endoplasmic reticulum/plasma membrane junctions via interaction with VAPA and VAPB. Proc Natl Acad Sci U S A 2018; 115:E7331-E7340. [PMID: 29941597 DOI: 10.1073/pnas.1805757115] [Citation(s) in RCA: 112] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Kv2.1 exhibits two distinct forms of localization patterns on the neuronal plasma membrane: One population is freely diffusive and regulates electrical activity via voltage-dependent K+ conductance while a second one localizes to micrometer-sized clusters that contain densely packed, but nonconducting, channels. We have previously established that these clusters represent endoplasmic reticulum/plasma membrane (ER/PM) junctions that function as membrane trafficking hubs and that Kv2.1 plays a structural role in forming these membrane contact sites in both primary neuronal cultures and transfected HEK cells. Clustering and the formation of ER/PM contacts are regulated by phosphorylation within the channel C terminus, offering cells fast, dynamic control over the physical relationship between the cortical ER and PM. The present study addresses the mechanisms by which Kv2.1 and the related Kv2.2 channel interact with the ER membrane. Using proximity-based biotinylation techniques in transfected HEK cells we identified ER VAMP-associated proteins (VAPs) as potential Kv2.1 interactors. Confirmation that Kv2.1 and -2.2 bind VAPA and VAPB employed colocalization/redistribution, siRNA knockdown, and Förster resonance energy transfer (FRET)-based assays. CD4 chimeras containing sequence from the Kv2.1 C terminus were used to identify a noncanonical VAP-binding motif. VAPs were first identified as proteins required for neurotransmitter release in Aplysia and are now known to be abundant scaffolding proteins involved in membrane contact site formation throughout the ER. The VAP interactome includes AKAPs, kinases, membrane trafficking machinery, and proteins regulating nonvesicular lipid transport from the ER to the PM. Therefore, the Kv2-induced VAP concentration at ER/PM contact sites is predicted to have wide-ranging effects on neuronal cell biology.
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Fan HK, Luo TX, Zhao WD, Mu YH, Yang Y, Guo WJ, Tu HY, Zhang Q. Functional interaction of Junctophilin 2 with small- conductance Ca 2+ -activated potassium channel subtype 2(SK2) in mouse cardiac myocytes. Acta Physiol (Oxf) 2018; 222. [PMID: 29055091 PMCID: PMC6084295 DOI: 10.1111/apha.12986] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2017] [Revised: 10/15/2017] [Accepted: 10/15/2017] [Indexed: 12/17/2022]
Abstract
Aim Junctophilins (JPs), a protein family of the junctional membrane complex, maintain the close conjunction between cell surface and intracellular membranes in striate muscle cells mediating the crosstalk between extracellular Ca2+ entry and intracellular Ca2+ release. The small‐conductance Ca2+‐activated K+ channels are activated by the intracellular calcium and play an essential role in the cardiac action potential profile. Molecular mechanisms of regulation of the SK channels are still uncertain. Here, we sought to determine whether there is a functional interaction of junctophilin type 2 (JP2) with the SK channels and whether JP2 gene silencing might modulate the function of SK channels in cardiac myocytes. Methods Association of JP2 with SK2 channel in mouse heart tissue as well as HEK293 cells was studied using in vivo and in vitro approaches. siRNA knockdown of JP2 gene was assessed by real‐time PCR. The expression of proteins was analysed by Western blotting. Ca2+‐activated K+ current (IK,Ca) in infected adult mouse cardiac myocytes was recorded using whole‐cell voltage‐clamp technique. The intracellular Ca2+ transient was measured using an IonOptix photometry system. Results We showed for the first time that JP2 associates with the SK2 channel in native cardiac tissue. JP2, via the membrane occupation and recognition nexus (MORN motifs) in its N‐terminus, directly interacted with SK2 channels. A colocalization of the SK2 channel with its interaction protein of JP2 was found in the cardiac myocytes. Moreover, we demonstrated that JP2 is necessary for the proper cell surface expression of the SK2 channel in HEK293. Functional experiments indicated that knockdown of JP2 caused a significant decrease in the density of IK,Ca and reduced the amplitude of the Ca2+ transient in infected cardiomyocytes. Conclusion The present data provide evidence that the functional interaction between JP2 and SK2 channels is present in the native mouse heart tissue. Junctophilin 2, as junctional membrane complex (JMC) protein, is an important regulator of the cardiac SK channels.
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Affiliation(s)
- H. K. Fan
- Department of Physiology; School of Medicine; Zhengzhou University; Zhengzhou China
| | - T. X. Luo
- Department of Physiology; School of Medicine; Zhengzhou University; Zhengzhou China
| | - W. D. Zhao
- Faculty of Medicine; KU Leuven; Leuven Belgium
| | - Y. H. Mu
- Department of Pathophysiology; School of Medicine; Xinxiang Medical College; Xinxiang China
| | - Y. Yang
- Department of Physiology; School of Medicine; Zhengzhou University; Zhengzhou China
| | - W. J. Guo
- Department of Physiology; School of Medicine; Zhengzhou University; Zhengzhou China
| | - H. Y. Tu
- Department of Physiology; School of Medicine; Zhengzhou University; Zhengzhou China
| | - Q. Zhang
- Department of Physiology; School of Medicine; Zhengzhou University; Zhengzhou China
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Calpena E, López Del Amo V, Chakraborty M, Llamusí B, Artero R, Espinós C, Galindo MI. The Drosophila junctophilin gene is functionally equivalent to its four mammalian counterparts and is a modifier of a Huntingtin poly-Q expansion and the Notch pathway. Dis Model Mech 2018; 11:dmm.029082. [PMID: 29208631 PMCID: PMC5818072 DOI: 10.1242/dmm.029082] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Accepted: 11/08/2017] [Indexed: 12/13/2022] Open
Abstract
Members of the Junctophilin (JPH) protein family have emerged as key actors in all excitable cells, with crucial implications for human pathophysiology. In mammals, this family consists of four members (JPH1-JPH4) that are differentially expressed throughout excitable cells. The analysis of knockout mice lacking JPH subtypes has demonstrated their essential contribution to physiological functions in skeletal and cardiac muscles and in neurons. Moreover, mutations in the human JPH2 gene are associated with hypertrophic and dilated cardiomyopathies; mutations in JPH3 are responsible for the neurodegenerative Huntington's disease-like-2 (HDL2), whereas JPH1 acts as a genetic modifier in Charcot–Marie–Tooth 2K peripheral neuropathy. Drosophila melanogaster has a single junctophilin (jp) gene, as is the case in all invertebrates, which might retain equivalent functions of the four homologous JPH genes present in mammalian genomes. Therefore, owing to the lack of putatively redundant genes, a jpDrosophila model could provide an excellent platform to model the Junctophilin-related diseases, to discover the ancestral functions of the JPH proteins and to reveal new pathways. By up- and downregulation of Jp in a tissue-specific manner in Drosophila, we show that altering its levels of expression produces a phenotypic spectrum characterized by muscular deficits, dilated cardiomyopathy and neuronal alterations. Importantly, our study has demonstrated that Jp modifies the neuronal degeneration in a Drosophila model of Huntington's disease, and it has allowed us to uncover an unsuspected functional relationship with the Notch pathway. Therefore, this Drosophila model has revealed new aspects of Junctophilin function that can be relevant for the disease mechanisms of their human counterparts. Summary: This work reveals that the Drosophila Junctophilin protein has similar functions to its mammalian homologues and uncovers new interactions of potential biomedical interest with Huntingtin and Notch signalling.
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Affiliation(s)
- Eduardo Calpena
- Program in Molecular Mechanisms of Disease, Centro de Investigación Príncipe Felipe (CIPF), c/ Eduardo Primo Yúfera no. 3, 46012 Valencia, Spain
| | - Víctor López Del Amo
- Program in Molecular Mechanisms of Disease, Centro de Investigación Príncipe Felipe (CIPF), c/ Eduardo Primo Yúfera no. 3, 46012 Valencia, Spain
| | - Mouli Chakraborty
- Translational Genomics Group, Incliva Health Research Institute, Avda. Menendez Pelayo 4 acc 46010, Valencia, Spain.,Department of Genetics and Estructura de Recerca Interdisciplinar en Biotecnologia i Biomedicina (ERI BIOTECMED), Universitat de València, c/ Dr Moliner 50, 46100 Burjasot, Spain
| | - Beatriz Llamusí
- Translational Genomics Group, Incliva Health Research Institute, Avda. Menendez Pelayo 4 acc 46010, Valencia, Spain.,Department of Genetics and Estructura de Recerca Interdisciplinar en Biotecnologia i Biomedicina (ERI BIOTECMED), Universitat de València, c/ Dr Moliner 50, 46100 Burjasot, Spain
| | - Rubén Artero
- Translational Genomics Group, Incliva Health Research Institute, Avda. Menendez Pelayo 4 acc 46010, Valencia, Spain.,Department of Genetics and Estructura de Recerca Interdisciplinar en Biotecnologia i Biomedicina (ERI BIOTECMED), Universitat de València, c/ Dr Moliner 50, 46100 Burjasot, Spain
| | - Carmen Espinós
- Program in Molecular Mechanisms of Disease, Centro de Investigación Príncipe Felipe (CIPF), c/ Eduardo Primo Yúfera no. 3, 46012 Valencia, Spain.,UPV-CIPF Joint Unit Disease Mechanisms and Nanomedicine, 46012 Valencia, Spain
| | - Máximo I Galindo
- Program in Molecular Mechanisms of Disease, Centro de Investigación Príncipe Felipe (CIPF), c/ Eduardo Primo Yúfera no. 3, 46012 Valencia, Spain .,UPV-CIPF Joint Unit Disease Mechanisms and Nanomedicine, 46012 Valencia, Spain.,Instituto Interuniversitario de Investigación de Reconocimiento Molecular y Desarrollo Tecnológico (IDM), Universitat Politècnica de València, Universitat de València, 46022 Valencia, Spain
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Abstract
There has been a significant progress in our understanding of the molecular mechanisms by which calcium (Ca2+) ions mediate various types of cardiac arrhythmias. A growing list of inherited gene defects can cause potentially lethal cardiac arrhythmia syndromes, including catecholaminergic polymorphic ventricular tachycardia, congenital long QT syndrome, and hypertrophic cardiomyopathy. In addition, acquired deficits of multiple Ca2+-handling proteins can contribute to the pathogenesis of arrhythmias in patients with various types of heart disease. In this review article, we will first review the key role of Ca2+ in normal cardiac function-in particular, excitation-contraction coupling and normal electric rhythms. The functional involvement of Ca2+ in distinct arrhythmia mechanisms will be discussed, followed by various inherited arrhythmia syndromes caused by mutations in Ca2+-handling proteins. Finally, we will discuss how changes in the expression of regulation of Ca2+ channels and transporters can cause acquired arrhythmias, and how these mechanisms might be targeted for therapeutic purposes.
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Affiliation(s)
- Andrew P Landstrom
- From the Section of Cardiology, Department of Pediatrics (A.P.L.), Cardiovascular Research Institute (A.P.L., X.H.T.W.), and Departments of Molecular Physiology and Biophysics, Medicine (Cardiology), Center for Space Medicine (X.H.T.W.), Baylor College of Medicine, Houston, TX; and Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Essen, Germany (D.D.)
| | - Dobromir Dobrev
- From the Section of Cardiology, Department of Pediatrics (A.P.L.), Cardiovascular Research Institute (A.P.L., X.H.T.W.), and Departments of Molecular Physiology and Biophysics, Medicine (Cardiology), Center for Space Medicine (X.H.T.W.), Baylor College of Medicine, Houston, TX; and Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Essen, Germany (D.D.)
| | - Xander H T Wehrens
- From the Section of Cardiology, Department of Pediatrics (A.P.L.), Cardiovascular Research Institute (A.P.L., X.H.T.W.), and Departments of Molecular Physiology and Biophysics, Medicine (Cardiology), Center for Space Medicine (X.H.T.W.), Baylor College of Medicine, Houston, TX; and Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Essen, Germany (D.D.).
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Hu X, Kuang Y, Li L, Tang H, Shi Q, Shu X, Zhang Y, Chan FKL, Tao Q, He C. Epigenomic and Functional Characterization of Junctophilin 3 (JPH3) as a Novel Tumor Suppressor Being Frequently Inactivated by Promoter CpG Methylation in Digestive Cancers. Am J Cancer Res 2017; 7:2150-2163. [PMID: 28656064 PMCID: PMC5485426 DOI: 10.7150/thno.18185] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Accepted: 04/04/2017] [Indexed: 12/28/2022] Open
Abstract
Junctophilin (JPH) proteins stabilize junctional membrane complexes between plasma membrane and endoplasmic reticulum, also implicated in some human diseases. JPH3 mutations are linked to Huntington's disease-like 2 syndrome. Through epigenomic study of a colon cancer cell line pair (HCT116 and DKO), we identified JPH3 as a methylated novel tumor suppressor gene (TSG) candidate at 16q24. We further studied its epigenetic alterations and functions in digestive tumorigenesis. JPH3 expression at the RNA level was found to be frequently silenced or reduced in colorectal and gastric cancers due to its promoter CpG methylation, which is associated with tumor progression and poor survival of digestive cancer patients. Ectopic expression of JPH3 inhibited tumor cell growth in vitro and in vivo. JPH3 expression upregulated the cytosolic Ca2+ levels, and unfolded protein response gene expression upon endoplasmic reticulum stress. JPH3 also induced calpain activation and subsequent mitochondrial membrane depolarization and cell apoptosis. Thus, JPH3 was identified as a novel TSG methylated in colorectal and gastric tumors which promotes mitochondrial-mediated apoptosis, also as a potential metastasis and survival biomarker for digestive cancers.
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Chang CL, Chen YJ, Liou J. ER-plasma membrane junctions: Why and how do we study them? BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2017; 1864:1494-1506. [PMID: 28554772 DOI: 10.1016/j.bbamcr.2017.05.018] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 05/09/2017] [Accepted: 05/17/2017] [Indexed: 12/17/2022]
Abstract
Endoplasmic reticulum (ER)-plasma membrane (PM) junctions are membrane microdomains important for communication between the ER and the PM. ER-PM junctions were first reported in muscle cells in 1957, but mostly ignored in non-excitable cells due to their scarcity and lack of functional significance. In 2005, the discovery of stromal interaction molecule 1 (STIM1) mediating a universal Ca2+ feedback mechanism at ER-PM junctions in mammalian cells led to a resurgence of research interests toward ER-PM junctions. In the past decade, several major advancements have been made in this emerging topic in cell biology, including the generation of tools for labeling ER-PM junctions and the unraveling of mechanisms underlying regulation and functions of ER-PM junctions. This review summarizes early studies, recently developed tools, and current advances in the characterization and understanding of ER-PM junctions. This article is part of a Special Issue entitled: Membrane Contact Sites edited by Christian Ungermann and Benoit Kornmann.
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Affiliation(s)
- Chi-Lun Chang
- Department of Physiology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Yu-Ju Chen
- Department of Physiology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Jen Liou
- Department of Physiology, UT Southwestern Medical Center, Dallas, TX 75390, USA.
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Quick AP, Landstrom AP, Wang Q, Beavers DL, Reynolds JO, Barreto-Torres G, Tran V, Showell J, Philippen LE, Morris SA, Skapura D, Bos JM, Pedersen SE, Pautler RG, Ackerman MJ, Wehrens XHT. Novel junctophilin-2 mutation A405S is associated with basal septal hypertrophy and diastolic dysfunction. ACTA ACUST UNITED AC 2017; 2:56-67. [PMID: 28393127 PMCID: PMC5384575 DOI: 10.1016/j.jacbts.2016.11.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
A JPH2 A405S mutation was found in a human HCM patient. A novel echocardiographic imaging plane revealed septal hypertrophy in a mouse model bearing the human JPH2 mutation, thereby causally linking it to HCM pathogenesis. This alpha helical JPH2 mutation resulted in decreased transverse tubule regularity and aberrant calcium handling in septal cardiomyocytes.
Junctophilin-2 (JPH2) is a structural calcium (Ca2+) handling protein, which approximates the cardiomyocyte transverse tubules (TTs) to the sarcoplasmic reticulum. This facilitates communication of the voltage-gated Ca2+ channel and the ryanodine receptor RyR2. A human patient with hypertrophic cardiomyopathy was positive for a JPH2 mutation substituting alanine-405—located within the alpha helix domain—with a serine (A405S). Using a novel mouse echocardiography plane, we found that mice bearing this JPH2 mutation developed increased subvalvular septal thickness. Cardiomyocytes from the septa of these mice displayed irregular TTs and abnormal Ca2+ handling including increased SERCA activity.
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Affiliation(s)
- Ann P Quick
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX, USA; Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX, USA
| | - Andrew P Landstrom
- Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX, USA; Department of Pediatrics (Cardiology), Baylor College of Medicine, Houston, TX, USA
| | - Qiongling Wang
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX, USA; Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX, USA
| | - David L Beavers
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX, USA; Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX, USA
| | - Julia O Reynolds
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX, USA; Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX, USA
| | - Giselle Barreto-Torres
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX, USA; Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX, USA
| | - Viet Tran
- Department of Medicine (Cardiology), Baylor College of Medicine, Houston, TX, USA
| | - Jordan Showell
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX, USA; Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX, USA
| | - Leonne E Philippen
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX, USA; Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX, USA
| | - Shaine A Morris
- Department of Pediatrics (Cardiology), Baylor College of Medicine, Houston, TX, USA
| | - Darlene Skapura
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX, USA; Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX, USA
| | - J Martijn Bos
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, Minnesota, USA
| | - Steen E Pedersen
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX, USA
| | - Robia G Pautler
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX, USA
| | - Michael J Ackerman
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, Minnesota, USA
| | - Xander H T Wehrens
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX, USA; Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX, USA; Department of Medicine (Cardiology), Baylor College of Medicine, Houston, TX, USA
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Immunological Disorders: Regulation of Ca 2+ Signaling in T Lymphocytes. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 993:397-424. [PMID: 28900926 DOI: 10.1007/978-3-319-57732-6_21] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Engagement of T cell receptors (TCRs) with cognate antigens triggers cascades of signaling pathways in helper T cells. TCR signaling is essential for the effector function of helper T cells including proliferation, differentiation, and cytokine production. It also modulates effector T cell fate by inducing cell death, anergy (nonresponsiveness), exhaustion, and generation of regulatory T cells. One of the main axes of TCR signaling is the Ca2+-calcineurin-nuclear factor of activated T cells (NFAT) signaling pathway. Stimulation of TCRs triggers depletion of intracellular Ca2+ store and, in turn, activates store-operated Ca2+ entry (SOCE) to raise the intracellular Ca2+ concentration. SOCE in T cells is mediated by the Ca2+ release-activated Ca2+ (CRAC) channels, which have been very well characterized in terms of their electrophysiological properties. Identification of STIM1 as a sensor to detect depletion of the endoplasmic reticulum (ER) Ca2+ store and Orai1 as the pore subunit of CRAC channels has dramatically advanced our understanding of the regulatory mechanism of Ca2+ signaling in T cells. In this review, we discuss our current understanding of Ca2+ signaling in T cells with specific focus on the mechanism of CRAC channel activation and regulation via protein interactions. In addition, we will discuss the role of CRAC channels in effector T cells, based on the analyses of genetically modified animal models.
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Reynolds JO, Quick AP, Wang Q, Beavers DL, Philippen LE, Showell J, Barreto-Torres G, Thuerauf DJ, Doroudgar S, Glembotski CC, Wehrens XHT. Junctophilin-2 gene therapy rescues heart failure by normalizing RyR2-mediated Ca 2+ release. Int J Cardiol 2016; 225:371-380. [PMID: 27760414 DOI: 10.1016/j.ijcard.2016.10.021] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Revised: 10/05/2016] [Accepted: 10/07/2016] [Indexed: 11/27/2022]
Abstract
BACKGROUND Junctophilin-2 (JPH2) is the primary structural protein for the coupling of transverse (T)-tubule associated cardiac L-type Ca channels and type-2 ryanodine receptors on the sarcoplasmic reticulum within junctional membrane complexes (JMCs) in cardiomyocytes. Effective signaling between these channels ensures adequate Ca-induced Ca release required for normal cardiac contractility. Disruption of JMC subcellular domains, a common feature of failing hearts, has been attributed to JPH2 downregulation. Here, we tested the hypothesis that adeno-associated virus type 9 (AAV9) mediated overexpression of JPH2 could halt the development of heart failure in a mouse model of transverse aortic constriction (TAC). METHODS AND RESULTS Following TAC, a progressive decrease in ejection fraction was paralleled by a progressive decrease of cardiac JPH2 levels. AAV9-mediated expression of JPH2 rescued cardiac contractility in mice subjected to TAC. AAV9-JPH2 also preserved T-tubule structure. Moreover, the Ca2+ spark frequency was reduced and the Ca2+ transient amplitude was increased in AAV9-JPH2 mice following TAC, consistent with JPH2-mediated normalization of SR Ca2+ handling. CONCLUSIONS This study demonstrates that AAV9-mediated JPH2 gene therapy maintained cardiac function in mice with early stage heart failure. Moreover, restoration of JPH2 levels prevented loss of T-tubules and suppressed abnormal SR Ca2+ leak associated with contractile failure following TAC. These findings suggest that targeting JPH2 might be an attractive therapeutic approach for treating pathological cardiac remodeling during heart failure.
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Affiliation(s)
- Julia O Reynolds
- Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX 77030, USA; Dept. of Molecular Physiology & Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Ann P Quick
- Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX 77030, USA; Dept. of Molecular Physiology & Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Qiongling Wang
- Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX 77030, USA; Dept. of Molecular Physiology & Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
| | - David L Beavers
- Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX 77030, USA; Translational Biology and Molecular Medicine Program, Baylor College of Medicine, Houston, TX 77030, USA
| | - Leonne E Philippen
- Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX 77030, USA; Dept. of Molecular Physiology & Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Jordan Showell
- Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX 77030, USA; Dept. of Molecular Physiology & Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Giselle Barreto-Torres
- Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX 77030, USA; Dept. of Molecular Physiology & Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Donna J Thuerauf
- San Diego State University Heart Institute and Department of Biology, San Diego State University, San Diego, CA 92182, USA
| | - Shirin Doroudgar
- Department of Cardiology, Angiology, and Pneumology, University Hospital Heidelberg, Innere Medizin III, Im Neuenheimer Feld 669, 69120, Heidelberg, Germany; DZHK (German Centre for Cardiovascular Research), Partner Site Heidelberg/Mannheim, 69120, Heidelberg, Germany
| | - Christopher C Glembotski
- San Diego State University Heart Institute and Department of Biology, San Diego State University, San Diego, CA 92182, USA
| | - Xander H T Wehrens
- Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX 77030, USA; Dept. of Molecular Physiology & Biophysics, Baylor College of Medicine, Houston, TX 77030, USA; Dept. of Medicine/Cardiology, Baylor College of Medicine, Houston, TX 77030, USA; Dept. of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA.
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Gallo A, Vannier C, Galli T. Endoplasmic Reticulum-Plasma Membrane Associations:Structures and Functions. Annu Rev Cell Dev Biol 2016; 32:279-301. [PMID: 27298092 DOI: 10.1146/annurev-cellbio-111315-125024] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Inside eukaryotic cells, membrane contact sites (MCSs), regions where two membrane-bound organelles are apposed at less than 30 nm, generate regions of important lipid and calcium exchange. This review principally focuses on the structure and the function of MCSs between the endoplasmic reticulum (ER) and the plasma membrane (PM). Here we describe how tethering structures form and maintain these junctions and, in some instances, participate in their function. We then discuss recent insights into the mechanisms by which specific classes of proteins mediate nonvesicular lipid exchange between the ER and PM and how such phenomena, already known to be crucial for maintaining organelle identity, are also emerging as regulators of cell growth and development.
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Affiliation(s)
- Alessandra Gallo
- Membrane Traffic in Health & Disease Group (INSERM ERL U950), F-75013 Paris, France;
| | - Christian Vannier
- Membrane Traffic in Health & Disease Group (INSERM ERL U950), F-75013 Paris, France;
| | - Thierry Galli
- Membrane Traffic in Health & Disease Group (INSERM ERL U950), F-75013 Paris, France;
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Junctophilin-4, a component of the endoplasmic reticulum-plasma membrane junctions, regulates Ca2+ dynamics in T cells. Proc Natl Acad Sci U S A 2016; 113:2762-7. [PMID: 26929330 DOI: 10.1073/pnas.1524229113] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Orai1 and stromal interaction molecule 1 (STIM1) mediate store-operated Ca(2+) entry (SOCE) in immune cells. STIM1, an endoplasmic reticulum (ER) Ca(2+) sensor, detects store depletion and interacts with plasma membrane (PM)-resident Orai1 channels at the ER-PM junctions. However, the molecular composition of these junctions in T cells remains poorly understood. Here, we show that junctophilin-4 (JP4), a member of junctional proteins in excitable cells, is expressed in T cells and localized at the ER-PM junctions to regulate Ca(2+) signaling. Silencing or genetic manipulation of JP4 decreased ER Ca(2+) content and SOCE in T cells, impaired activation of the nuclear factor of activated T cells (NFAT) and extracellular signaling-related kinase (ERK) signaling pathways, and diminished expression of activation markers and cytokines. Mechanistically, JP4 directly interacted with STIM1 via its cytoplasmic domain and facilitated its recruitment into the junctions. Accordingly, expression of this cytoplasmic fragment of JP4 inhibited SOCE. Furthermore, JP4 also formed a complex with junctate, a Ca(2+)-sensing ER-resident protein, previously shown to mediate STIM1 recruitment into the junctions. We propose that the junctate-JP4 complex located at the junctions cooperatively interacts with STIM1 to maintain ER Ca(2+) homeostasis and mediate SOCE in T cells.
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Functional Impact of Ryanodine Receptor Oxidation on Intracellular Calcium Regulation in the Heart. Rev Physiol Biochem Pharmacol 2016; 171:39-62. [PMID: 27251471 DOI: 10.1007/112_2016_2] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Type 2 ryanodine receptor (RyR2) serves as the major intracellular Ca2+ release channel that drives heart contraction. RyR2 is activated by cytosolic Ca2+ via the process of Ca2+-induced Ca2+ release (CICR). To ensure stability of Ca2+ dynamics, the self-reinforcing CICR must be tightly controlled. Defects in this control cause sarcoplasmic reticulum (SR) Ca2+ mishandling, which manifests in a variety of cardiac pathologies that include myocardial infarction and heart failure. These pathologies are also associated with oxidative stress. Given that RyR2 contains a large number of cysteine residues, it is no surprise that RyR2 plays a key role in the cellular response to oxidative stress. RyR's many cysteine residues pose an experimental limitation in defining a specific target or mechanism of action for oxidative stress. As a result, the current understanding of redox-mediated RyR2 dysfunction remains incomplete. Several oxidative modifications, including S-glutathionylation and S-nitrosylation, have been suggested playing an important role in the regulation of RyR2 activity. Moreover, oxidative stress can increase RyR2 activity by forming disulfide bonds between two neighboring subunits (intersubunit cross-linking). Since intersubunit interactions within the RyR2 homotetramer complex dictate the channel gating, such posttranslational modification of RyR2 would have a significant impact on RyR2 function and Ca2+ regulation. This review summarizes recent findings on oxidative modifications of RyR2 and discusses contributions of these RyR2 modifications to SR Ca2+ mishandling during cardiac pathologies.
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Krause A, Mitchell C, Essop F, Tager S, Temlett J, Stevanin G, Ross C, Rudnicki D, Margolis R. Junctophilin 3 (JPH3) expansion mutations causing Huntington disease like 2 (HDL2) are common in South African patients with African ancestry and a Huntington disease phenotype. Am J Med Genet B Neuropsychiatr Genet 2015; 168:573-85. [PMID: 26079385 PMCID: PMC4565761 DOI: 10.1002/ajmg.b.32332] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 05/28/2015] [Indexed: 12/12/2022]
Abstract
Huntington disease (HD) is a progressive autosomal dominant neurodegenerative disorder, characterized by abnormal movements, cognitive decline, and psychiatric symptoms, caused by a CAG repeat expansion in the huntingtin (HTT) gene on chromosome 4p. A CAG/CTG repeat expansion in the junctophilin-3 (JPH3) gene on chromosome 16q24.2 causes a Huntington disease-like phenotype (HDL2). All patients to date with HDL2 have some African ancestry. The present study aimed to characterize the genetic basis of the Huntington disease phenotype in South Africans and to investigate the possible origin of the JPH3 mutation. In a sample of unrelated South African individuals referred for diagnostic HD testing, 62% (106/171) of white patients compared to only 36% (47/130) of black patients had an expansion in HTT. However, 15% (20/130) of black South African patients and no white patients (0/171) had an expansion in JPH3, confirming the diagnosis of Huntington disease like 2 (HDL2). Individuals with HDL2 share many clinical features with individuals with HD and are clinically indistinguishable in many cases, although the average age of onset and diagnosis in HDL2 is 5 years later than HD and individual clinical features may be more prominent. HDL2 mutations contribute significantly to the HD phenotype in South Africans with African ancestry. JPH3 haplotype studies in 31 families, mainly from South Africa and North America, provide evidence for a founder mutation and support a common African origin for all HDL2 patients. Molecular testing in individuals with an HD phenotype and African ancestry should include testing routinely for JPH3 mutations.
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Affiliation(s)
- Amanda Krause
- Division of Human Genetics, National Health Laboratory Service, Johannesburg, South Africa
- Division of Human Genetics, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Claire Mitchell
- Division of Human Genetics, National Health Laboratory Service, Johannesburg, South Africa
| | - Fahmida Essop
- Division of Human Genetics, National Health Laboratory Service, Johannesburg, South Africa
- Division of Human Genetics, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Susan Tager
- Department of Neurology, University of the Witwatersrand, Johannesburg, South Africa
- Donald Gordon Medical Centre, Johannesburg, South Africa
| | - James Temlett
- Department of Neurology, University of the Witwatersrand, Johannesburg, South Africa
- Department Clinical Neurology, University of Adelaide and the Royal Adelaide Hospital, Adelaide, Australia
| | - Giovanni Stevanin
- Sorbonne Universités, UPMC Univ Paris, Institut du Cerveau et de la Moelle épinière, Paris, France
- Ecole Pratique des Hautes Etudes, Paris, France
| | - Christopher Ross
- Johns Hopkins University School of Medicine, Departments of Psychiatry, Neurology, Neuroscience, and Pharmacology and Molecular Sciences and Program in Cellular and Molecular Medicine, Baltimore, Maryland
| | - Dobrila Rudnicki
- Johns Hopkins University School of Medicine, Departments of Psychiatry and Program in Cellular and Molecular Medicine, Baltimore, Maryland
| | - Russell Margolis
- Johns Hopkins University School of Medicine, Departments of Psychiatry and Neurology and Program in Cellular and Molecular Medicine, Baltimore, Maryland
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Lee MY, Park C, Berent RM, Park PJ, Fuchs R, Syn H, Chin A, Townsend J, Benson CC, Redelman D, Shen TW, Park JK, Miano JM, Sanders KM, Ro S. Smooth Muscle Cell Genome Browser: Enabling the Identification of Novel Serum Response Factor Target Genes. PLoS One 2015; 10:e0133751. [PMID: 26241044 PMCID: PMC4524680 DOI: 10.1371/journal.pone.0133751] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Accepted: 06/30/2015] [Indexed: 11/18/2022] Open
Abstract
Genome-scale expression data on the absolute numbers of gene isoforms offers essential clues in cellular functions and biological processes. Smooth muscle cells (SMCs) perform a unique contractile function through expression of specific genes controlled by serum response factor (SRF), a transcription factor that binds to DNA sites known as the CArG boxes. To identify SRF-regulated genes specifically expressed in SMCs, we isolated SMC populations from mouse small intestine and colon, obtained their transcriptomes, and constructed an interactive SMC genome and CArGome browser. To our knowledge, this is the first online resource that provides a comprehensive library of all genetic transcripts expressed in primary SMCs. The browser also serves as the first genome-wide map of SRF binding sites. The browser analysis revealed novel SMC-specific transcriptional variants and SRF target genes, which provided new and unique insights into the cellular and biological functions of the cells in gastrointestinal (GI) physiology. The SRF target genes in SMCs, which were discovered in silico, were confirmed by proteomic analysis of SMC-specific Srf knockout mice. Our genome browser offers a new perspective into the alternative expression of genes in the context of SRF binding sites in SMCs and provides a valuable reference for future functional studies.
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Affiliation(s)
- Moon Young Lee
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, United States of America
- Department of Physiology, Wonkwang Digestive Disease Research Institute and Institute of Wonkwang Medical Science, School of Medicine, Wonkwang University, Iksan, Jeollabuk-do, Korea
| | - Chanjae Park
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, United States of America
| | - Robyn M. Berent
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, United States of America
| | - Paul J. Park
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, United States of America
| | - Robert Fuchs
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, United States of America
| | - Hannah Syn
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, United States of America
| | - Albert Chin
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, United States of America
| | - Jared Townsend
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, United States of America
| | - Craig C. Benson
- Aab Cardiovascular Research Institute, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America
| | - Doug Redelman
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, United States of America
| | - Tsai-wei Shen
- LC Sciences, 2575 West Bellfort Street Suite 270, Houston, Texas, United States of America
| | - Jong Kun Park
- Division of Biological Science, Wonkwang University, Iksan, Jeollabuk-do, South Korea
| | - Joseph M. Miano
- Aab Cardiovascular Research Institute, University of Rochester School of Medicine and Dentistry, Rochester, New York, United States of America
| | - Kenton M. Sanders
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, United States of America
| | - Seungil Ro
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, United States of America
- * E-mail:
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Paolini P, Pick D, Lapira J, Sannino G, Pasqualini L, Ludka C, Sprague LJ, Zhang X, Bartolotta EA, Vazquez-Hidalgo E, Barba DT, Bazan C, Hardiman G. Developmental and extracellular matrix-remodeling processes in rosiglitazone-exposed neonatal rat cardiomyocytes. Pharmacogenomics 2015; 15:759-74. [PMID: 24897284 DOI: 10.2217/pgs.14.39] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
OBJECTIVE The objective of this study was to investigate the effects of rosiglitazone (Avandia(®)) on gene expression in neonatal rat ventricular myocytes. MATERIALS & METHODS Myocytes were exposed to rosiglitazone ex vivo. The two factors examined in the experiment were drug exposure (rosiglitazone and dimethyl sulfoxide vs dimethyl sulfoxide), and length of exposure to drug (½ h, 1 h, 2 h, 4 h, 6 h, 8 h, 12 h, 18 h, 24 h, 36 h and 48 h). RESULTS Transcripts that were consistently expressed in response to the drug were identified. Cardiovascular system development, extracellular matrix and immune response are represented prominently among the significantly modified gene ontology terms. CONCLUSION Hmgcs2, Angptl4, Cpt1a, Cyp1b1, Ech1 and Nqo1 mRNAs were strongly upregulated in cells exposed to rosiglitazone. Enrichment of transcripts involved in cardiac muscle cell differentiation and the extracellular matrix provides a panel of biomarkers for further analysis in the context of adverse cardiac outcomes in humans. Original submitted 15 November 2013; Revision submitted 14 February 2014.
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Affiliation(s)
- Paul Paolini
- Department of Biology, San Diego State University, CA, USA
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Kralt A, Carretta M, Mari M, Reggiori F, Steen A, Poolman B, Veenhoff LM. Intrinsically Disordered Linker and Plasma Membrane-Binding Motif Sort Ist2 and Ssy1 to Junctions. Traffic 2014; 16:135-47. [DOI: 10.1111/tra.12243] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Revised: 11/17/2014] [Accepted: 11/18/2014] [Indexed: 12/25/2022]
Affiliation(s)
- Annemarie Kralt
- European Institute for the Biology of Ageing (ERIBA); University of Groningen, University Medical Center Groningen, Netherlands Proteomics Centre; Antonius Deusinglaan 1 9713 AV Groningen The Netherlands
| | - Marco Carretta
- European Institute for the Biology of Ageing (ERIBA); University of Groningen, University Medical Center Groningen, Netherlands Proteomics Centre; Antonius Deusinglaan 1 9713 AV Groningen The Netherlands
- Current address: Department of Hematology, University of Groningen, Hanzeplein 1, 9713 GZ Groningen, The Netherlands
| | - Muriel Mari
- Department of Cell Biology; Center for Molecular Medicine, University Medical Center Utrecht; Heidelberglaan 100 3584 CX Utrecht The Netherlands
| | - Fulvio Reggiori
- Department of Cell Biology; Center for Molecular Medicine, University Medical Center Utrecht; Heidelberglaan 100 3584 CX Utrecht The Netherlands
| | - Anton Steen
- European Institute for the Biology of Ageing (ERIBA); University of Groningen, University Medical Center Groningen, Netherlands Proteomics Centre; Antonius Deusinglaan 1 9713 AV Groningen The Netherlands
| | - Bert Poolman
- Department of Biochemistry; University of Groningen; Nijenborgh 4 9747 AG Groningen The Netherlands
| | - Liesbeth M. Veenhoff
- European Institute for the Biology of Ageing (ERIBA); University of Groningen, University Medical Center Groningen, Netherlands Proteomics Centre; Antonius Deusinglaan 1 9713 AV Groningen The Netherlands
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Pla-Martín D, Calpena E, Lupo V, Márquez C, Rivas E, Sivera R, Sevilla T, Palau F, Espinós C. Junctophilin-1 is a modifier gene of GDAP1-related Charcot-Marie-Tooth disease. Hum Mol Genet 2014; 24:213-29. [PMID: 25168384 DOI: 10.1093/hmg/ddu440] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Mutations in the GDAP1 gene cause different forms of Charcot-Marie-Tooth (CMT) disease, and the primary clinical expression of this disease is markedly variable in the dominant inheritance form (CMT type 2K; CMT2K), in which carriers of the GDAP1 p.R120W mutation can display a wide range of clinical severity. We investigated the JPH1 gene as a genetic modifier of clinical expression variability because junctophilin-1 (JPH1) is a good positional and functional candidate. We demonstrated that the JPH1-GDAP1 cluster forms a paralogon and is conserved in vertebrates. Moreover, both proteins play a role in Ca(2+) homeostasis, and we demonstrated that JPH1 is able to restore the store-operated Ca(2+) entry (SOCE) activity in GDAP1-silenced cells. After the mutational screening of JPH1 in a series of 24 CMT2K subjects who harbour the GDAP1 p.R120W mutation, we characterized the JPH1 p.R213P mutation in one patient with a more severe clinical picture. JPH1(p.R213P) cannot rescue the SOCE response in GDAP1-silenced cells. We observed that JPH1 colocalizes with STIM1, which is the activator of SOCE, in endoplasmic reticulum-plasma membrane puncta structures during Ca(2+) release in a GDAP1-dependent manner. However, when GDAP1(p.R120W) is expressed, JPH1 seems to be retained in mitochondria. We also established that the combination of GDAP1(p.R120W) and JPH1(p.R213P) dramatically reduces SOCE activity, mimicking the effect observed in GDAP1 knock-down cells. In summary, we conclude that JPH1 and GDAP1 share a common pathway and depend on each other; therefore, JPH1 can contribute to the phenotypical consequences of GDAP1 mutations.
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Affiliation(s)
- David Pla-Martín
- Program in Rare and Genetic Diseases and IBV/CSIC Associated Unit, Centro de Investigación Príncipe Felipe (CIPF), Valencia 46012, Spain Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Valencia 46012, Spain
| | - Eduardo Calpena
- Program in Rare and Genetic Diseases and IBV/CSIC Associated Unit, Centro de Investigación Príncipe Felipe (CIPF), Valencia 46012, Spain Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Valencia 46012, Spain
| | - Vincenzo Lupo
- Program in Rare and Genetic Diseases and IBV/CSIC Associated Unit, Centro de Investigación Príncipe Felipe (CIPF), Valencia 46012, Spain Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Valencia 46012, Spain
| | | | - Eloy Rivas
- Department of Pathology, Hospital Universitario Virgen del Rocío, Seville 41013, Spain
| | - Rafael Sivera
- Department of Neurology, Hospital Universitari i Politècnic La Fe and Instituto de Investigación Sanitario (IIS)-La Fe, Valencia 46026, Spain Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Valencia 46026, Spain
| | - Teresa Sevilla
- Department of Neurology, Hospital Universitari i Politècnic La Fe and Instituto de Investigación Sanitario (IIS)-La Fe, Valencia 46026, Spain Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Valencia 46026, Spain Department of Medicine and
| | - Francesc Palau
- Program in Rare and Genetic Diseases and IBV/CSIC Associated Unit, Centro de Investigación Príncipe Felipe (CIPF), Valencia 46012, Spain Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Valencia 46012, Spain University of Castilla-La Mancha School of Medicine, Ciudad Real 13071, Spain
| | - Carmen Espinós
- Program in Rare and Genetic Diseases and IBV/CSIC Associated Unit, Centro de Investigación Príncipe Felipe (CIPF), Valencia 46012, Spain Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Valencia 46012, Spain Department of Genetics, Universitat de València, Valencia 46010, Spain and
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(R)-PFI-2 is a potent and selective inhibitor of SETD7 methyltransferase activity in cells. Proc Natl Acad Sci U S A 2014; 111:12853-8. [PMID: 25136132 DOI: 10.1073/pnas.1407358111] [Citation(s) in RCA: 137] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
SET domain containing (lysine methyltransferase) 7 (SETD7) is implicated in multiple signaling and disease related pathways with a broad diversity of reported substrates. Here, we report the discovery of (R)-PFI-2-a first-in-class, potent (Ki (app) = 0.33 nM), selective, and cell-active inhibitor of the methyltransferase activity of human SETD7-and its 500-fold less active enantiomer, (S)-PFI-2. (R)-PFI-2 exhibits an unusual cofactor-dependent and substrate-competitive inhibitory mechanism by occupying the substrate peptide binding groove of SETD7, including the catalytic lysine-binding channel, and by making direct contact with the donor methyl group of the cofactor, S-adenosylmethionine. Chemoproteomics experiments using a biotinylated derivative of (R)-PFI-2 demonstrated dose-dependent competition for binding to endogenous SETD7 in MCF7 cells pretreated with (R)-PFI-2. In murine embryonic fibroblasts, (R)-PFI-2 treatment phenocopied the effects of Setd7 deficiency on Hippo pathway signaling, via modulation of the transcriptional coactivator Yes-associated protein (YAP) and regulation of YAP target genes. In confluent MCF7 cells, (R)-PFI-2 rapidly altered YAP localization, suggesting continuous and dynamic regulation of YAP by the methyltransferase activity of SETD7. These data establish (R)-PFI-2 and related compounds as a valuable tool-kit for the study of the diverse roles of SETD7 in cells and further validate protein methyltransferases as a druggable target class.
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Beavers DL, Landstrom AP, Chiang DY, Wehrens XHT. Emerging roles of junctophilin-2 in the heart and implications for cardiac diseases. Cardiovasc Res 2014; 103:198-205. [PMID: 24935431 DOI: 10.1093/cvr/cvu151] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Cardiomyocytes rely on a highly specialized subcellular architecture to maintain normal cardiac function. In a little over a decade, junctophilin-2 (JPH2) has become recognized as a cardiac structural protein critical in forming junctional membrane complexes (JMCs), which are subcellular domains essential for excitation-contraction coupling within the heart. While initial studies described the structure of JPH2 and its role in anchoring junctional sarcoplasmic reticulum and transverse-tubule (T-tubule) membrane invaginations, recent research has an expanded role of JPH2 in JMC structure and function. For example, JPH2 is necessary for the development of postnatal T-tubule in mammals. It is also critical for the maintenance of the complex JMC architecture and stabilization of local ion channels in mature cardiomyocytes. Loss of this function by mutations or down-regulation of protein expression has been linked to hypertrophic cardiomyopathy, arrhythmias, and progression of disease in failing hearts. In this review, we summarize current views on the roles of JPH2 within the heart and how JPH2 dysregulation may contribute to a variety of cardiac diseases.
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Affiliation(s)
- David L Beavers
- Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX, USA Translational Biology and Molecular Medicine Program, Baylor College of Medicine, Houston, TX, USA
| | - Andrew P Landstrom
- Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX, USA Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
| | - David Y Chiang
- Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX, USA Translational Biology and Molecular Medicine Program, Baylor College of Medicine, Houston, TX, USA
| | - Xander H T Wehrens
- Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX, USA Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX, USA Deptartment of Medicine (Cardiology), Baylor College of Medicine, Houston, TX, USA
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Landstrom AP, Beavers DL, Wehrens XHT. The junctophilin family of proteins: from bench to bedside. Trends Mol Med 2014; 20:353-62. [PMID: 24636942 PMCID: PMC4041816 DOI: 10.1016/j.molmed.2014.02.004] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Revised: 02/10/2014] [Accepted: 02/14/2014] [Indexed: 12/25/2022]
Abstract
Excitable tissues rely on junctional membrane complexes to couple cell surface signals to intracellular channels. The junctophilins have emerged as a family of proteins critical in coordinating the maturation and maintenance of this cellular ultrastructure. Within skeletal and cardiac muscle, junctophilin 1 and junctophilin 2, respectively, couple sarcolemmal and intracellular calcium channels. In neuronal tissue, junctophilin 3 and junctophilin 4 may have an emerging role in coupling membrane neurotransmitter receptors and intracellular calcium channels. These important physiological roles are highlighted by the pathophysiology which results when these proteins are perturbed, and a growing body of literature has associated junctophilins with the pathogenesis of human disease.
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Affiliation(s)
- Andrew P Landstrom
- Department of Pediatrics, Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX 77030, USA
| | - David L Beavers
- Department of Molecular Physiology and Biophysics, Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX 77030, USA
| | - Xander H T Wehrens
- Department of Molecular Physiology and Biophysics, Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX 77030, USA; Department of Medicine (Cardiology), Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX 77030, USA.
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Zima AV, Bovo E, Mazurek SR, Rochira JA, Li W, Terentyev D. Ca handling during excitation-contraction coupling in heart failure. Pflugers Arch 2014; 466:1129-37. [PMID: 24515294 DOI: 10.1007/s00424-014-1469-3] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Revised: 01/29/2014] [Accepted: 01/30/2014] [Indexed: 12/22/2022]
Abstract
In the heart, coupling between excitation of the surface membrane and activation of contractile apparatus is mediated by Ca released from the sarcoplasmic reticulum (SR). Several components of Ca machinery are perfectly arranged within the SR network and the T-tubular system to generate a regular Ca cycling and thereby rhythmic beating activity of the heart. Among these components, ryanodine receptor (RyR) and SR Ca ATPase (SERCA) complexes play a particularly important role and their dysfunction largely underlies abnormal Ca homeostasis in diseased hearts such as in heart failure. The abnormalities in Ca regulation occur at practically all main steps of Ca cycling in the failing heart, including activation and termination of SR Ca release, diastolic SR Ca leak, and SR Ca uptake. The contributions of these different mechanisms to depressed contractile function and enhanced arrhythmogenesis may vary in different HF models. This brief review will therefore focus on modifications in RyR and SERCA structure that occur in the failing heart and how these molecular modifications affect SR Ca regulation and excitation-contraction coupling.
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Affiliation(s)
- Aleksey V Zima
- Department of Cell and Molecular Physiology, Loyola University Chicago, Stritch School of Medicine, 2160 South First Avenue, Maywood, IL, 60153, USA,
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Vihola A, Sirito M, Bachinski LL, Raheem O, Screen M, Suominen T, Krahe R, Udd B. Altered expression and splicing of Ca(2+) metabolism genes in myotonic dystrophies DM1 and DM2. Neuropathol Appl Neurobiol 2013; 39:390-405. [PMID: 22758909 DOI: 10.1111/j.1365-2990.2012.01289.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
AIMS Myotonic dystrophy types 1 and 2 (DM1 and DM2) are multisystem disorders caused by similar repeat expansion mutations, with similar yet distinct clinical features. Aberrant splicing of multiple effector genes, as well as dysregulation of transcription and translation, has been suggested to underlie different aspects of the complex phenotypes in DM1 and DM2. Ca(2+) plays a central role in both muscle contraction and control of gene expression, and recent expression profiling studies have indicated major perturbations of the Ca(2+) signalling pathways in DM. Here we have further investigated the expression of genes and proteins involved in Ca(2+) metabolism in DM patients, including Ca(2+) channels and Ca(2+) binding proteins. METHODS We used patient muscle biopsies to analyse mRNA expression and splicing of genes by microarray expression profiling and RT-PCR. We studied protein expression by immunohistochemistry and immunoblotting. RESULTS Most of the genes studied showed mRNA up-regulation in expression profiling. When analysed by immunohistochemistry the Ca(2+) release channel ryanodine receptor was reduced in DM1 and DM2, as was calsequestrin 2, a sarcoplasmic reticulum lumen Ca(2+) storage protein. Abnormal splicing of ATP2A1 was more pronounced in DM2 than DM1. CONCLUSIONS We observed abnormal mRNA and protein expression in DM affecting several proteins involved in Ca(2+) metabolism, with some differences between DM1 and DM2. Our protein expression studies are suggestive of a post-transcriptional defect(s) in the myotonic dystrophies.
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Affiliation(s)
- A Vihola
- Folkhälsan Institute of Genetics and Department of Medical Genetics, Haartman Institute, University of Helsinki, Helsinki, Finland.
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Kott E, Legendre M, Copin B, Papon JF, Dastot-Le Moal F, Montantin G, Duquesnoy P, Piterboth W, Amram D, Bassinet L, Beucher J, Beydon N, Deneuville E, Houdouin V, Journel H, Just J, Nathan N, Tamalet A, Collot N, Jeanson L, Le Gouez M, Vallette B, Vojtek AM, Epaud R, Coste A, Clement A, Housset B, Louis B, Escudier E, Amselem S. Loss-of-function mutations in RSPH1 cause primary ciliary dyskinesia with central-complex and radial-spoke defects. Am J Hum Genet 2013; 93:561-70. [PMID: 23993197 DOI: 10.1016/j.ajhg.2013.07.013] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Revised: 07/09/2013] [Accepted: 07/16/2013] [Indexed: 12/22/2022] Open
Abstract
Primary ciliary dyskinesia (PCD) is a rare autosomal-recessive respiratory disorder resulting from defects of motile cilia. Various axonemal ultrastructural phenotypes have been observed, including one with so-called central-complex (CC) defects, whose molecular basis remains unexplained in most cases. To identify genes involved in this phenotype, whose diagnosis can be particularly difficult to establish, we combined homozygosity mapping and whole-exome sequencing in a consanguineous individual with CC defects. This identified a nonsense mutation in RSPH1, a gene whose ortholog in Chlamydomonas reinhardtii encodes a radial-spoke (RS)-head protein and is mainly expressed in respiratory and testis cells. Subsequent analyses of RSPH1 identified biallelic mutations in 10 of 48 independent families affected by CC defects. These mutations include splicing defects, as demonstrated by the study of RSPH1 transcripts obtained from airway cells of affected individuals. Wild-type RSPH1 localizes within cilia of airway cells, but we were unable to detect it in an individual with RSPH1 loss-of-function mutations. High-speed-videomicroscopy analyses revealed the coexistence of different ciliary beating patterns-cilia with a normal beat frequency but abnormal motion alongside immotile cilia or cilia with a slowed beat frequency-in each individual. This study shows that this gene is mutated in 20.8% of individuals with CC defects, whose diagnosis could now be improved by molecular screening. RSPH1 mutations thus appear as a major etiology for this PCD phenotype, which in fact includes RS defects, thereby unveiling the importance of RSPH1 in the proper building of CCs and RSs in humans.
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Affiliation(s)
- Esther Kott
- INSERM/UMR S933, Université Pierre et Marie Curie-Paris 6, Paris, France
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