1
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Mareedu S, Fefelova N, Galindo CL, Prakash G, Mukai R, Sadoshima J, Xie LH, Babu GJ. Improved mitochondrial function in the hearts of sarcolipin-deficient dystrophin and utrophin double-knockout mice. JCI Insight 2024; 9:e170185. [PMID: 38564291 DOI: 10.1172/jci.insight.170185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Accepted: 03/21/2024] [Indexed: 04/04/2024] Open
Abstract
Duchenne muscular dystrophy (DMD) is a progressive muscle-wasting disease associated with cardiomyopathy. DMD cardiomyopathy is characterized by abnormal intracellular Ca2+ homeostasis and mitochondrial dysfunction. We used dystrophin and utrophin double-knockout (mdx:utrn-/-) mice in a sarcolipin (SLN) heterozygous-knockout (sln+/-) background to examine the effect of SLN reduction on mitochondrial function in the dystrophic myocardium. Germline reduction of SLN expression in mdx:utrn-/- mice improved cardiac sarco/endoplasmic reticulum (SR) Ca2+ cycling, reduced cardiac fibrosis, and improved cardiac function. At the cellular level, reducing SLN expression prevented mitochondrial Ca2+ overload, reduced mitochondrial membrane potential loss, and improved mitochondrial function. Transmission electron microscopy of myocardial tissues and proteomic analysis of mitochondria-associated membranes showed that reducing SLN expression improved mitochondrial structure and SR-mitochondria interactions in dystrophic cardiomyocytes. These findings indicate that SLN upregulation plays a substantial role in the pathogenesis of cardiomyopathy and that reducing SLN expression has clinical implications in the treatment of DMD cardiomyopathy.
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MESH Headings
- Animals
- Utrophin/genetics
- Utrophin/metabolism
- Mice, Knockout
- Mice
- Dystrophin/genetics
- Dystrophin/metabolism
- Muscular Dystrophy, Duchenne/genetics
- Muscular Dystrophy, Duchenne/metabolism
- Muscular Dystrophy, Duchenne/pathology
- Mice, Inbred mdx
- Proteolipids/metabolism
- Proteolipids/genetics
- Cardiomyopathies/metabolism
- Cardiomyopathies/genetics
- Cardiomyopathies/pathology
- Muscle Proteins/metabolism
- Muscle Proteins/genetics
- Myocytes, Cardiac/metabolism
- Myocytes, Cardiac/pathology
- Calcium/metabolism
- Mitochondria, Heart/metabolism
- Mitochondria, Heart/ultrastructure
- Mitochondria, Heart/genetics
- Male
- Disease Models, Animal
- Myocardium/metabolism
- Myocardium/pathology
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Affiliation(s)
- Satvik Mareedu
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers University, Newark, New Jersey, USA
| | - Nadezhda Fefelova
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers University, Newark, New Jersey, USA
| | - Cristi L Galindo
- Vascular Medicine Institute and Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Goutham Prakash
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers University, Newark, New Jersey, USA
| | - Risa Mukai
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers University, Newark, New Jersey, USA
| | - Junichi Sadoshima
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers University, Newark, New Jersey, USA
| | - Lai-Hua Xie
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers University, Newark, New Jersey, USA
| | - Gopal J Babu
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers University, Newark, New Jersey, USA
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2
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Remark J, Tong J, Lin MJ, Concepcion A, Mareedu S, Babu GJ, Feske S, Lu CP. Neurotransmitter signaling specifies sweat gland stem cell fate through SLN-mediated intracellular calcium regulation. bioRxiv 2023:2023.09.10.557066. [PMID: 37745514 PMCID: PMC10515797 DOI: 10.1101/2023.09.10.557066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/26/2023]
Abstract
Sympathetic nerves co-develop with their target organs and release neurotransmitters to stimulate their functions after maturation. Here, we provide the molecular mechanism that during sweat gland morphogenesis, neurotransmitters released from sympathetic nerves act first to promote sweat duct elongation via norepinephrine and followed by acetylcholine to specify sweat gland stem cell fate, which matches the sequence of neurotransmitter switch. Without neuronal signals during development, the basal cells switch to exhibit suprabasal (luminal) cell features. Sarcolipin (SLN), a key regulator of sarcoendoplasmic reticulum (SR) Ca 2+ -ATPase (SERCA), expression is significantly down-regulated in the sweat gland myoepithelial cells upon denervation. Loss of SLN in sweat gland myoepithelial cells leads to decreased intracellular Ca 2+ over time in response to ACh stimulation, as well as upregulation of luminal cell features. In cell culture experiments, we showed that contrary to the paradigm that elevation of Ca 2+ promote epidermal differentiation, specification of the glandular myoepithelial (basal) cells requires high Ca 2+ while lowering Ca 2+ level promotes luminal (suprabasal) cell fate. Our work highlights that neuronal signals not only act transiently for mature sweat glands to function, but also exert long-term impact on glandular stem cell specification through regulating intracellular Ca 2+ dynamics.
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3
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Tong M, Mukai R, Mareedu S, Zhai P, Oka SI, Huang CY, Hsu CP, Yousufzai FAK, Fritzky L, Mizushima W, Babu GJ, Sadoshima J. Distinct Roles of DRP1 in Conventional and Alternative Mitophagy in Obesity Cardiomyopathy. Circ Res 2023; 133:6-21. [PMID: 37232152 PMCID: PMC10330464 DOI: 10.1161/circresaha.123.322512] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2023] [Accepted: 05/03/2023] [Indexed: 05/27/2023]
Abstract
BACKGROUND Obesity induces cardiomyopathy characterized by hypertrophy and diastolic dysfunction. Whereas mitophagy mediated through an Atg7 (autophagy related 7)-dependent mechanism serves as an essential mechanism to maintain mitochondrial quality during the initial development of obesity cardiomyopathy, Rab9 (Ras-related protein Rab-9A)-dependent alternative mitophagy takes over the role during the chronic phase. Although it has been postulated that DRP1 (dynamin-related protein 1)-mediated mitochondrial fission and consequent separation of the damaged portions of mitochondria are essential for mitophagy, the involvement of DRP1 in mitophagy remains controversial. We investigated whether endogenous DRP1 is essential in mediating the 2 forms of mitophagy during high-fat diet (HFD)-induced obesity cardiomyopathy and, if so, what the underlying mechanisms are. METHODS Mice were fed either a normal diet or an HFD (60 kcal %fat). Mitophagy was evaluated using cardiac-specific Mito-Keima mice. The role of DRP1 was evaluated using tamoxifen-inducible cardiac-specific Drp1knockout (Drp1 MCM) mice. RESULTS Mitophagy was increased after 3 weeks of HFD consumption. The induction of mitophagy by HFD consumption was completely abolished in Drp1 MCM mouse hearts, in which both diastolic and systolic dysfunction were exacerbated. The increase in LC3 (microtubule-associated protein 1 light chain 3)-dependent general autophagy and colocalization between LC3 and mitochondrial proteins was abolished in Drp1 MCM mice. Activation of alternative mitophagy was also completely abolished in Drp1 MCM mice during the chronic phase of HFD consumption. DRP1 was phosphorylated at Ser616, localized at the mitochondria-associated membranes, and associated with Rab9 and Fis1 (fission protein 1) only during the chronic, but not acute, phase of HFD consumption. CONCLUSIONS DRP1 is an essential factor in mitochondrial quality control during obesity cardiomyopathy that controls multiple forms of mitophagy. Although DRP1 regulates conventional mitophagy through a mitochondria-associated membrane-independent mechanism during the acute phase, it acts as a component of the mitophagy machinery at the mitochondria-associated membranes in alternative mitophagy during the chronic phase of HFD consumption.
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Affiliation(s)
- Mingming Tong
- Department of Cell Biology and Molecular Medicine, Rutgers New Jersey Medical School, USA
- Equal contribution
| | - Risa Mukai
- Department of Cell Biology and Molecular Medicine, Rutgers New Jersey Medical School, USA
- Equal contribution
| | - Satvik Mareedu
- Department of Cell Biology and Molecular Medicine, Rutgers New Jersey Medical School, USA
| | - Peiyong Zhai
- Department of Cell Biology and Molecular Medicine, Rutgers New Jersey Medical School, USA
| | - Shin-ichi Oka
- Department of Cell Biology and Molecular Medicine, Rutgers New Jersey Medical School, USA
| | - Chun-Yang Huang
- Division of Cardiovascular Surgery, Department of Surgery, Taipei Veterans General Hospital, Taipei, Taiwan
- Department of Medicine, School of Medicine, National Yang-Ming Chiao-Tung University, Taipei, Taiwan
| | - Chiao-Po Hsu
- Division of Cardiovascular Surgery, Department of Surgery, Taipei Veterans General Hospital, Taipei, Taiwan
- Department of Medicine, School of Medicine, National Yang-Ming Chiao-Tung University, Taipei, Taiwan
| | | | - Luke Fritzky
- Core Imaging Facility, Rutgers New Jersey Medical School, Newark, New Jersey, USA
| | - Wataru Mizushima
- Department of Cell Biology and Molecular Medicine, Rutgers New Jersey Medical School, USA
| | - Gopal J. Babu
- Department of Cell Biology and Molecular Medicine, Rutgers New Jersey Medical School, USA
| | - Junichi Sadoshima
- Department of Cell Biology and Molecular Medicine, Rutgers New Jersey Medical School, USA
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4
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Morales ED, Yue Y, Watkins TB, Han J, Pan X, Gibson AM, Hu B, Brito‐Estrada O, Yao G, Makarewich CA, Babu GJ, Duan D. Dwarf Open Reading Frame (DWORF) Gene Therapy Ameliorated Duchenne Muscular Dystrophy Cardiomyopathy in Aged mdx Mice. J Am Heart Assoc 2023; 12:e027480. [PMID: 36695318 PMCID: PMC9973626 DOI: 10.1161/jaha.122.027480] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 12/21/2022] [Indexed: 01/26/2023]
Abstract
Background Cardiomyopathy is a leading health threat in Duchenne muscular dystrophy (DMD). Cytosolic calcium upregulation is implicated in DMD cardiomyopathy. Calcium is primarily removed from the cytosol by the sarcoendoplasmic reticulum calcium ATPase (SERCA). SERCA activity is reduced in DMD. Improving SERCA function may treat DMD cardiomyopathy. Dwarf open reading frame (DWORF) is a recently discovered positive regulator for SERCA, hence, a potential therapeutic target. Methods and Results To study DWORF's involvement in DMD cardiomyopathy, we quantified DWORF expression in the heart of wild-type mice and the mdx model of DMD. To test DWORF gene therapy, we engineered and characterized an adeno-associated virus serotype 9-DWORF vector. To determine if this vector can mitigate DMD cardiomyopathy, we delivered it to 6-week-old mdx mice (6×1012 vector genome particles/mouse) via the tail vein. Exercise capacity, heart histology, and cardiac function were examined at 18 months of age. We found DWORF expression was significantly reduced at the transcript and protein levels in mdx mice. Adeno-associated virus serotype 9-DWORF vector significantly enhanced SERCA activity. Systemic adeno-associated virus serotype 9-DWORF therapy reduced myocardial fibrosis and improved treadmill running, electrocardiography, and heart hemodynamics. Conclusions Our data suggest that DWORF deficiency contributes to SERCA dysfunction in mdx mice and that DWORF gene therapy holds promise to treat DMD cardiomyopathy.
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Affiliation(s)
- Emily D. Morales
- Department of Molecular Microbiology and Immunology, School of MedicineThe University of MissouriColumbiaMO
| | - Yongping Yue
- Department of Molecular Microbiology and Immunology, School of MedicineThe University of MissouriColumbiaMO
| | - Thais B. Watkins
- Department of Molecular Microbiology and Immunology, School of MedicineThe University of MissouriColumbiaMO
| | - Jin Han
- Department of Molecular Microbiology and Immunology, School of MedicineThe University of MissouriColumbiaMO
| | - Xiufang Pan
- Department of Molecular Microbiology and Immunology, School of MedicineThe University of MissouriColumbiaMO
| | - Aaron M. Gibson
- Division of Molecular Cardiovascular Biology, Cincinnati Children’s Hospital Medical CenterThe Heart InstituteCincinnatiOH
| | - Bryan Hu
- Department of Molecular Microbiology and Immunology, School of MedicineThe University of MissouriColumbiaMO
| | - Omar Brito‐Estrada
- Division of Molecular Cardiovascular Biology, Cincinnati Children’s Hospital Medical CenterThe Heart InstituteCincinnatiOH
| | - Gang Yao
- Department of Biomedical, Biological & Chemical Engineering, College of EngineeringThe University of MissouriColumbiaMO
| | - Catherine A. Makarewich
- Division of Molecular Cardiovascular Biology, Cincinnati Children’s Hospital Medical CenterThe Heart InstituteCincinnatiOH
- Department of PediatricsThe University of Cincinnati College of MedicineCincinnatiOH
| | - Gopal J. Babu
- Department of Cell Biology and Molecular MedicineRutgers, New Jersey Medical SchoolNewarkNJ
| | - Dongsheng Duan
- Department of Molecular Microbiology and Immunology, School of MedicineThe University of MissouriColumbiaMO
- Department of Biomedical, Biological & Chemical Engineering, College of EngineeringThe University of MissouriColumbiaMO
- Department of Neurology, School of MedicineThe University of MissouriColumbiaMO
- Department of Biomedical Sciences, College of Veterinary MedicineThe University of MissouriColumbiaMO
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5
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Marchioretti C, Zanetti G, Pirazzini M, Gherardi G, Nogara L, Andreotti R, Martini P, Marcucci L, Canato M, Nath SR, Zuccaro E, Chivet M, Mammucari C, Pacifici M, Raffaello A, Rizzuto R, Mattarei A, Desbats MA, Salviati L, Megighian A, Sorarù G, Pegoraro E, Belluzzi E, Pozzuoli A, Biz C, Ruggieri P, Romualdi C, Lieberman AP, Babu GJ, Sandri M, Blaauw B, Basso M, Pennuto M. Defective excitation-contraction coupling and mitochondrial respiration precede mitochondrial Ca 2+ accumulation in spinobulbar muscular atrophy skeletal muscle. Nat Commun 2023; 14:602. [PMID: 36746942 PMCID: PMC9902403 DOI: 10.1038/s41467-023-36185-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 01/19/2023] [Indexed: 02/08/2023] Open
Abstract
Polyglutamine expansion in the androgen receptor (AR) causes spinobulbar muscular atrophy (SBMA). Skeletal muscle is a primary site of toxicity; however, the current understanding of the early pathological processes that occur and how they unfold during disease progression remains limited. Using transgenic and knock-in mice and patient-derived muscle biopsies, we show that SBMA mice in the presymptomatic stage develop a respiratory defect matching defective expression of genes involved in excitation-contraction coupling (ECC), altered contraction dynamics, and increased fatigue. These processes are followed by stimulus-dependent accumulation of calcium into mitochondria and structural disorganization of the muscle triads. Deregulation of expression of ECC genes is concomitant with sexual maturity and androgen raise in the serum. Consistent with the androgen-dependent nature of these alterations, surgical castration and AR silencing alleviate the early and late pathological processes. These observations show that ECC deregulation and defective mitochondrial respiration are early but reversible events followed by altered muscle force, calcium dyshomeostasis, and dismantling of triad structure.
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Affiliation(s)
- Caterina Marchioretti
- Department of Biomedical Sciences (DBS), University of Padova, 35131, Padova, Italy
- Veneto Institute of Molecular Medicine (VIMM), Padova, 35100, Italy
- Padova Neuroscience Center (PNC), Padova, 35100, Italy
- Dulbecco Telethon Institute (DTI) at the Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, 38123, Trento, Italy
| | - Giulia Zanetti
- Department of Biomedical Sciences (DBS), University of Padova, 35131, Padova, Italy
| | - Marco Pirazzini
- Department of Biomedical Sciences (DBS), University of Padova, 35131, Padova, Italy
- CIR-Myo, Centro Interdipartimentale di Ricerca di Miologia, University of Padova, 35131, Padova, Italy
| | - Gaia Gherardi
- Department of Biomedical Sciences (DBS), University of Padova, 35131, Padova, Italy
| | - Leonardo Nogara
- Department of Biomedical Sciences (DBS), University of Padova, 35131, Padova, Italy
- Veneto Institute of Molecular Medicine (VIMM), Padova, 35100, Italy
| | - Roberta Andreotti
- Department of Biomedical Sciences (DBS), University of Padova, 35131, Padova, Italy
- Veneto Institute of Molecular Medicine (VIMM), Padova, 35100, Italy
- Padova Neuroscience Center (PNC), Padova, 35100, Italy
| | - Paolo Martini
- Department of Molecular and Translational Medicine, University of Brescia, 25121, Brescia, Italy
| | - Lorenzo Marcucci
- Department of Biomedical Sciences (DBS), University of Padova, 35131, Padova, Italy
| | - Marta Canato
- Department of Biomedical Sciences (DBS), University of Padova, 35131, Padova, Italy
| | - Samir R Nath
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Emanuela Zuccaro
- Department of Biomedical Sciences (DBS), University of Padova, 35131, Padova, Italy
- Veneto Institute of Molecular Medicine (VIMM), Padova, 35100, Italy
- Padova Neuroscience Center (PNC), Padova, 35100, Italy
| | - Mathilde Chivet
- Dulbecco Telethon Institute (DTI) at the Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, 38123, Trento, Italy
| | - Cristina Mammucari
- Department of Biomedical Sciences (DBS), University of Padova, 35131, Padova, Italy
- CIR-Myo, Centro Interdipartimentale di Ricerca di Miologia, University of Padova, 35131, Padova, Italy
| | - Marco Pacifici
- Department of Biomedical Sciences (DBS), University of Padova, 35131, Padova, Italy
| | - Anna Raffaello
- Department of Biomedical Sciences (DBS), University of Padova, 35131, Padova, Italy
- CIR-Myo, Centro Interdipartimentale di Ricerca di Miologia, University of Padova, 35131, Padova, Italy
| | - Rosario Rizzuto
- Department of Biomedical Sciences (DBS), University of Padova, 35131, Padova, Italy
| | - Andrea Mattarei
- Department of Pharmaceutical and Pharmacological Sciences, University of Padova, 35131, Padova, Italy
| | - Maria A Desbats
- Clinical Genetics Unit, Department of Women and Children's Health, University of Padova, and Fondazione Istituto di Ricerca Pediatrica Città della Speranza, Padova, Italy
| | - Leonardo Salviati
- CIR-Myo, Centro Interdipartimentale di Ricerca di Miologia, University of Padova, 35131, Padova, Italy
- Clinical Genetics Unit, Department of Women and Children's Health, University of Padova, and Fondazione Istituto di Ricerca Pediatrica Città della Speranza, Padova, Italy
| | - Aram Megighian
- Department of Biomedical Sciences (DBS), University of Padova, 35131, Padova, Italy
- Padova Neuroscience Center (PNC), Padova, 35100, Italy
| | - Gianni Sorarù
- Padova Neuroscience Center (PNC), Padova, 35100, Italy
- Department of Neuroscience (DNS), University of Padova, 35128, Padova, Italy
| | - Elena Pegoraro
- Department of Neuroscience (DNS), University of Padova, 35128, Padova, Italy
| | - Elisa Belluzzi
- Orthopedics and Orthopedic Oncology, Department of Surgery, Oncology, and Gastroenterology DiSCOG, University-Hospital of Padova, 35128, Padova, Italy
- Musculoskeletal Pathology and Oncology Laboratory, Department of Surgery, Oncology and Gastroenterology (DiSCOG), University of Padova, 35128, Padova, Italy
| | - Assunta Pozzuoli
- Orthopedics and Orthopedic Oncology, Department of Surgery, Oncology, and Gastroenterology DiSCOG, University-Hospital of Padova, 35128, Padova, Italy
- Musculoskeletal Pathology and Oncology Laboratory, Department of Surgery, Oncology and Gastroenterology (DiSCOG), University of Padova, 35128, Padova, Italy
| | - Carlo Biz
- Orthopedics and Orthopedic Oncology, Department of Surgery, Oncology, and Gastroenterology DiSCOG, University-Hospital of Padova, 35128, Padova, Italy
| | - Pietro Ruggieri
- Orthopedics and Orthopedic Oncology, Department of Surgery, Oncology, and Gastroenterology DiSCOG, University-Hospital of Padova, 35128, Padova, Italy
| | - Chiara Romualdi
- Department of Biology, University of Padova, Padova, 35100, Italy
| | - Andrew P Lieberman
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Gopal J Babu
- Department of Cell Biology and Molecular Medicine, Rutgers, New Jersey Medical School, Newark, NJ, 07103, USA
| | - Marco Sandri
- Department of Biomedical Sciences (DBS), University of Padova, 35131, Padova, Italy
- Veneto Institute of Molecular Medicine (VIMM), Padova, 35100, Italy
| | - Bert Blaauw
- Department of Biomedical Sciences (DBS), University of Padova, 35131, Padova, Italy
- Veneto Institute of Molecular Medicine (VIMM), Padova, 35100, Italy
| | - Manuela Basso
- Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, 38123, Trento, Italy
| | - Maria Pennuto
- Department of Biomedical Sciences (DBS), University of Padova, 35131, Padova, Italy.
- Veneto Institute of Molecular Medicine (VIMM), Padova, 35100, Italy.
- Padova Neuroscience Center (PNC), Padova, 35100, Italy.
- Dulbecco Telethon Institute (DTI) at the Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, 38123, Trento, Italy.
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6
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Abstract
Duchenne muscular dystrophy (DMD) is an inherited muscle wasting disease. Metabolic impairments and oxidative stress are major secondary mechanisms that severely worsen muscle function in DMD. Here, we sought to determine whether germline reduction or ablation of sarcolipin (SLN), an inhibitor of sarco/endoplasmic reticulum (SR) Ca2+ ATPase (SERCA), improves muscle metabolism and ameliorates muscle pathology in the mdx mouse model of DMD. Glucose and insulin tolerance tests show that glucose clearance rate and insulin sensitivity were improved in the SLN haploinsufficient mdx (mdx:sln+/-) and SLN-deficient mdx (mdx:sln-/-) mice. The histopathological analysis shows that fibrosis and necrosis were significantly reduced in muscles of mdx:sln+/- and mdx:sln-/- mice. SR Ca2+ uptake, mitochondrial complex protein levels, complex activities, mitochondrial Ca2+ uptake and release, and mitochondrial metabolism were significantly improved, and lipid peroxidation and protein carbonylation were reduced in the muscles of mdx:sln+/- and mdx:sln-/- mice. These data demonstrate that reduction or ablation of SLN expression can improve muscle metabolism, reduce oxidative stress, decrease muscle pathology, and protects the mdx mice from glucose intolerance.
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Affiliation(s)
- Rekha Balakrishnan
- Department of Cell Biology and Molecular Medicine, Rutgers, New Jersey Medical School, Newark, New Jersey
| | - Satvik Mareedu
- Department of Cell Biology and Molecular Medicine, Rutgers, New Jersey Medical School, Newark, New Jersey
| | - Gopal J. Babu
- Department of Cell Biology and Molecular Medicine, Rutgers, New Jersey Medical School, Newark, New Jersey
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7
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Mareedu S, Fefelova N, Xie LH, Babu GJ. Abstract P385: Sarcolipin Reduction Prevents Mitochondrial Dysfunction In Dystrophic Myocardium. Circ Res 2021. [DOI: 10.1161/res.129.suppl_1.p385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Rationale & Hypothesis:
Sarcolipin (SLN), an inhibitor of sarco/endoplasmic reticulum Ca
2+
ATPase (SERCA) is abnormally high and enriched in the mitochondrial associated membrane (MAM) fractions of dystrophic hearts. We, therefore, hypothesized that in the dystrophic cardiomyocytes, SLN upregulation causes abnormal elevation of intracellular Ca
2+
(Ca
2+
i
) including Ca
2+
mishandling in the MAM region, resulting in sustained elevation of mitochondrial Ca
2+
(Ca
2+
m
)
,
which in turn affects mitochondrial structure and function.
Approach:
We chose dystrophin mutant and utrophin deficient, mdx:utr
-/-
mice for our studies and generated SLN haploinsufficient mdx:utr
-/-
(mdx:utr
-/-
:sln
+/-
) mice. Single-cell Ca
2+
transients and
Ca
2+
m
efflux were measured in isolated cardiomyocytes to determine
Ca
2+
i
handling and
Ca
2+
m
content, respectively. Mitochondrial membrane potential was assessed with membrane-permeant dyes in isolated cardiomyocytes followed by confocal imaging. Mitochondrial respiration was measured using Complex activity assays and Seahorse metabolic profiling in ventricular tissue lysates and isolated mitochondria respectively. Mitochondrial structure, number, and area were evaluated using electron micrographs.
Results:
Heterozygous deletion of the SLN gene normalized SLN expression and improved Ca
2+
i
cycling and prevented
Ca
2+
m
overload in dystrophic cardiac myocytes. Furthermore, reducing SLN expression prevents loss of membrane potential and improves mitochondrial respiration in the dystrophic cardiac myocytes. Transmission electron microscopic analyses of the dystrophic heart revealed significant cristae loss in the mitochondria globally as well as in the MAM-associated mitochondria. On the other hand, the reduction in SLN expression prevents these changes.
Conclusions:
In conclusion, reduction in SLN expression preserves the SR-mitochondrial interface and restores the mitochondrial function by mitigating the
Ca
2+
overload, membrane potential loss, and structural damage. These changes improve cardiac function and prevent the development of cardiomyopathy in
mdx:utr
-/-
mice. Our findings suggest that SLN reduction could be a potential therapeutic strategy for the treatment of Duchenne muscular dystrophy and associated cardiomyopathy.
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Affiliation(s)
| | | | - Lai-hua Xie
- RUTGERS-NEW JERSEY MEDICAL SCHOOL, Newark, NJ
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8
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Francisco J, Zhang Y, Nakada Y, Jeong JI, Huang CY, Ivessa A, Oka S, Babu GJ, Del Re DP. AAV-mediated YAP expression in cardiac fibroblasts promotes inflammation and increases fibrosis. Sci Rep 2021; 11:10553. [PMID: 34006931 PMCID: PMC8131354 DOI: 10.1038/s41598-021-89989-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 05/05/2021] [Indexed: 12/12/2022] Open
Abstract
Fibrosis is a hallmark of heart disease independent of etiology and is thought to contribute to impaired cardiac dysfunction and development of heart failure. However, the underlying mechanisms that regulate the differentiation of fibroblasts to myofibroblasts and fibrotic responses remain incompletely defined. As a result, effective treatments to mitigate excessive fibrosis are lacking. We recently demonstrated that the Hippo pathway effector Yes-associated protein (YAP) is an important mediator of myofibroblast differentiation and fibrosis in the infarcted heart. Yet, whether YAP activation in cardiac fibroblasts is sufficient to drive fibrosis, and how fibroblast YAP affects myocardial inflammation, a significant component of adverse cardiac remodeling, are largely unknown. In this study, we leveraged adeno-associated virus (AAV) to target cardiac fibroblasts and demonstrate that chronic YAP expression upregulated indices of fibrosis and inflammation in the absence of additional stress. YAP occupied the Ccl2 gene and promoted Ccl2 expression, which was associated with increased macrophage infiltration, pro-inflammatory cytokine expression, collagen deposition, and cardiac dysfunction in mice with cardiac fibroblast-targeted YAP overexpression. These results are consistent with other recent reports and extend our understanding of YAP function in modulating fibrotic and inflammatory responses in the heart.
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Affiliation(s)
- Jamie Francisco
- Department of Cell Biology and Molecular Medicine, Cardiovascular Research Institute, Rutgers New Jersey Medical School, 185 South Orange Avenue, MSB G-609, Newark, NJ, 07103, USA
| | - Yu Zhang
- Department of Cell Biology and Molecular Medicine, Cardiovascular Research Institute, Rutgers New Jersey Medical School, 185 South Orange Avenue, MSB G-609, Newark, NJ, 07103, USA
| | - Yasuki Nakada
- Department of Cell Biology and Molecular Medicine, Cardiovascular Research Institute, Rutgers New Jersey Medical School, 185 South Orange Avenue, MSB G-609, Newark, NJ, 07103, USA
| | - Jae Im Jeong
- Department of Cell Biology and Molecular Medicine, Cardiovascular Research Institute, Rutgers New Jersey Medical School, 185 South Orange Avenue, MSB G-609, Newark, NJ, 07103, USA
| | - Chun-Yang Huang
- Department of Cell Biology and Molecular Medicine, Cardiovascular Research Institute, Rutgers New Jersey Medical School, 185 South Orange Avenue, MSB G-609, Newark, NJ, 07103, USA
| | - Andreas Ivessa
- Department of Cell Biology and Molecular Medicine, Cardiovascular Research Institute, Rutgers New Jersey Medical School, 185 South Orange Avenue, MSB G-609, Newark, NJ, 07103, USA
| | - Shinichi Oka
- Department of Cell Biology and Molecular Medicine, Cardiovascular Research Institute, Rutgers New Jersey Medical School, 185 South Orange Avenue, MSB G-609, Newark, NJ, 07103, USA
| | - Gopal J Babu
- Department of Cell Biology and Molecular Medicine, Cardiovascular Research Institute, Rutgers New Jersey Medical School, 185 South Orange Avenue, MSB G-609, Newark, NJ, 07103, USA
| | - Dominic P Del Re
- Department of Cell Biology and Molecular Medicine, Cardiovascular Research Institute, Rutgers New Jersey Medical School, 185 South Orange Avenue, MSB G-609, Newark, NJ, 07103, USA.
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9
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Mareedu S, Million ED, Duan D, Babu GJ. Abnormal Calcium Handling in Duchenne Muscular Dystrophy: Mechanisms and Potential Therapies. Front Physiol 2021; 12:647010. [PMID: 33897454 PMCID: PMC8063049 DOI: 10.3389/fphys.2021.647010] [Citation(s) in RCA: 54] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Accepted: 03/02/2021] [Indexed: 12/18/2022] Open
Abstract
Duchenne muscular dystrophy (DMD) is an X-linked muscle-wasting disease caused by the loss of dystrophin. DMD is associated with muscle degeneration, necrosis, inflammation, fatty replacement, and fibrosis, resulting in muscle weakness, respiratory and cardiac failure, and premature death. There is no curative treatment. Investigations on disease-causing mechanisms offer an opportunity to identify new therapeutic targets to treat DMD. An abnormal elevation of the intracellular calcium (Cai2+) concentration in the dystrophin-deficient muscle is a major secondary event, which contributes to disease progression in DMD. Emerging studies have suggested that targeting Ca2+-handling proteins and/or mechanisms could be a promising therapeutic strategy for DMD. Here, we provide an updated overview of the mechanistic roles the sarcolemma, sarcoplasmic/endoplasmic reticulum, and mitochondria play in the abnormal and sustained elevation of Cai2+ levels and their involvement in DMD pathogenesis. We also discuss current approaches aimed at restoring Ca2+ homeostasis as potential therapies for DMD.
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Affiliation(s)
- Satvik Mareedu
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers University, Newark, NJ, United States
| | - Emily D Million
- Department of Molecular Microbiology and Immunology, The University of Missouri, Columbia, MO, United States
| | - Dongsheng Duan
- Department of Molecular Microbiology and Immunology, The University of Missouri, Columbia, MO, United States.,Department of Biomedical, Biological & Chemical Engineering, The University of Missouri, Columbia, MO, United States
| | - Gopal J Babu
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers University, Newark, NJ, United States
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10
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Mareedu S, Pachon R, Thilagavathi J, Fefelova N, Balakrishnan R, Niranjan N, Xie LH, Babu GJ. Sarcolipin haploinsufficiency prevents dystrophic cardiomyopathy in mdx mice. Am J Physiol Heart Circ Physiol 2021; 320:H200-H210. [PMID: 33216625 PMCID: PMC7847070 DOI: 10.1152/ajpheart.00601.2020] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 10/21/2020] [Accepted: 11/17/2020] [Indexed: 02/07/2023]
Abstract
Sarcolipin (SLN) is an inhibitor of sarco/endoplasmic reticulum (SR) Ca2+-ATPase (SERCA) and expressed at high levels in the ventricles of animal models for and patients with Duchenne muscular dystrophy (DMD). The goal of this study was to determine whether the germline ablation of SLN expression improves cardiac SERCA function and intracellular Ca2+ (Ca2+i) handling and prevents cardiomyopathy in the mdx mouse model of DMD. Wild-type, mdx, SLN-haploinsufficient mdx (mdx:sln+/-), and SLN-deficient mdx (mdx:sln-/-) mice were used for this study. SERCA function and Ca2+i handling were determined by Ca2+ uptake assays and by measuring single-cell Ca2+ transients, respectively. Age-dependent disease progression was determined by histopathological examinations and by echocardiography in 6-, 12-, and 20-mo-old mice. Gene expression changes in the ventricles of mdx:sln+/- mice were determined by RNA-Seq analysis. SERCA function and Ca2+i cycling were improved in the ventricles of mdx:sln+/- mice. Fibrosis and necrosis were significantly decreased, and cardiac function was enhanced in the mdx:sln+/- mice until the study endpoint. The mdx:sln-/- mice also exhibited similar beneficial effects. RNA-Seq analysis identified distinct gene expression changes including the activation of the apelin pathway in the ventricles of mdx:sln+/- mice. Our findings suggest that reducing SLN expression is sufficient to improve cardiac SERCA function and Ca2+i cycling and prevent cardiomyopathy in mdx mice.NEW & NOTEWORTHY First, reducing sarcopolin (SLN) expression improves sarco/endoplasmic reticulum Ca2+ uptake and intracellular Ca2+ handling and prevents cardiomyopathy in mdx mice. Second, reducing SLN expression prevents diastolic dysfunction and improves cardiac contractility in mdx mice Third, reducing SLN expression activates apelin-mediated cardioprotective signaling pathways in mdx heart.
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Affiliation(s)
- Satvik Mareedu
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers University, Newark, New Jersey
| | - Ronald Pachon
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers University, Newark, New Jersey
| | - Jayapalraj Thilagavathi
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers University, Newark, New Jersey
| | - Nadezhda Fefelova
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers University, Newark, New Jersey
| | - Rekha Balakrishnan
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers University, Newark, New Jersey
| | - Nandita Niranjan
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers University, Newark, New Jersey
| | - Lai-Hua Xie
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers University, Newark, New Jersey
| | - Gopal J Babu
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers University, Newark, New Jersey
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11
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Wasala NB, Yue Y, Lostal W, Wasala LP, Niranjan N, Hajjar RJ, Babu GJ, Duan D. Single SERCA2a Therapy Ameliorated Dilated Cardiomyopathy for 18 Months in a Mouse Model of Duchenne Muscular Dystrophy. Mol Ther 2020; 28:845-854. [PMID: 31981493 DOI: 10.1016/j.ymthe.2019.12.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 12/20/2019] [Accepted: 12/28/2019] [Indexed: 01/16/2023] Open
Abstract
Loss of dystrophin leads to Duchenne muscular dystrophy (DMD). A pathogenic feature of DMD is the significant elevation of cytosolic calcium. Supraphysiological calcium triggers protein degradation, membrane damage, and eventually muscle death and dysfunction. Sarcoplasmic/endoplasmic reticulum (SR) calcium ATPase (SERCA) is a calcium pump that transports cytosolic calcium to the SR during excitation-contraction coupling. We hypothesize that a single systemic delivery of SERCA2a with adeno-associated virus (AAV) may improve calcium recycling and provide long-lasting benefits in DMD. To test this, we injected an AAV9 human SERCA2a vector (6 × 1012 viral genome particles/mouse) intravenously to 3-month-old mdx mice, the most commonly used DMD model. Immunostaining and western blot showed robust human SERCA2a expression in the heart and skeletal muscle for 18 months. Concomitantly, SR calcium uptake was significantly improved in these tissues. SERCA2a therapy significantly enhanced grip force and treadmill performance, completely prevented myocardial fibrosis, and normalized electrocardiograms (ECGs). Cardiac catheterization showed normalization of multiple systolic and diastolic hemodynamic parameters in treated mice. Importantly, chamber dilation was completely prevented, and ejection fraction was restored to the wild-type level. Our results suggest that a single systemic AAV9 SERCA2a therapy has the potential to provide long-lasting benefits for DMD.
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Affiliation(s)
- Nalinda B Wasala
- Department of Molecular Microbiology and Immunology, School of Medicine, University of Missouri, Columbia, MO 65212, USA
| | - Yongping Yue
- Department of Molecular Microbiology and Immunology, School of Medicine, University of Missouri, Columbia, MO 65212, USA
| | - William Lostal
- Department of Molecular Microbiology and Immunology, School of Medicine, University of Missouri, Columbia, MO 65212, USA
| | - Lakmini P Wasala
- Department of Molecular Microbiology and Immunology, School of Medicine, University of Missouri, Columbia, MO 65212, USA
| | - Nandita Niranjan
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers University, Newark, NJ 07103, USA
| | | | - Gopal J Babu
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers University, Newark, NJ 07103, USA
| | - Dongsheng Duan
- Department of Molecular Microbiology and Immunology, School of Medicine, University of Missouri, Columbia, MO 65212, USA; Department of Neurology, School of Medicine, University of Missouri, Columbia, MO 65212, USA; Department of Biomedical, Biological & Chemical Engineering, College of Engineering, University of Missouri, Columbia, MO 65212, USA; Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, MO 65212, USA.
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12
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Niranjan N, Mareedu S, Tian Y, Kodippili K, Fefelova N, Voit A, Xie LH, Duan D, Babu GJ. Sarcolipin overexpression impairs myogenic differentiation in Duchenne muscular dystrophy. Am J Physiol Cell Physiol 2019; 317:C813-C824. [PMID: 31365291 DOI: 10.1152/ajpcell.00146.2019] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Reduction in the expression of sarcolipin (SLN), an inhibitor of sarco(endo)plasmic reticulum (SR) Ca2+-ATPase (SERCA), ameliorates severe muscular dystrophy in mice. However, the mechanism by which SLN inhibition improves muscle structure remains unclear. Here, we describe the previously unknown function of SLN in muscle differentiation in Duchenne muscular dystrophy (DMD). Overexpression of SLN in C2C12 resulted in decreased SERCA pump activity, reduced SR Ca2+ load, and increased intracellular Ca2+ (Cai2+) concentration. In addition, SLN overexpression resulted in altered expression of myogenic markers and poor myogenic differentiation. In dystrophin-deficient dog myoblasts and myotubes, SLN expression was significantly high and associated with defective Cai2+ cycling. The dystrophic dog myotubes were less branched and associated with decreased autophagy and increased expression of mitochondrial fusion and fission proteins. Reduction in SLN expression restored these changes and enhanced dystrophic dog myoblast fusion during differentiation. In summary, our data suggest that SLN upregulation is an intrinsic secondary change in dystrophin-deficient myoblasts and could account for the Cai2+ mishandling, which subsequently contributes to poor myogenic differentiation. Accordingly, reducing SLN expression can improve the Cai2+ cycling and differentiation of dystrophic myoblasts. These findings provide cellular-level supports for targeting SLN expression as a therapeutic strategy for DMD.
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Affiliation(s)
- Nandita Niranjan
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers University, Newark, New Jersey
| | - Satvik Mareedu
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers University, Newark, New Jersey
| | - Yimin Tian
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers University, Newark, New Jersey
| | - Kasun Kodippili
- Department of Molecular Microbiology and Immunology, University of Missouri, Columbia, Missouri
| | - Nadezhda Fefelova
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers University, Newark, New Jersey
| | - Antanina Voit
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers University, Newark, New Jersey
| | - Lai-Hua Xie
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers University, Newark, New Jersey
| | - Dongsheng Duan
- Department of Molecular Microbiology and Immunology, University of Missouri, Columbia, Missouri.,Department of Neurology, University of Missouri, Columbia, Missouri.,Department of Biomedical, Biological & Chemical Engineering, University of Missouri, Columbia, Missouri.,Department of Biomedical Sciences, University of Missouri, Columbia, Missouri
| | - Gopal J Babu
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers University, Newark, New Jersey
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13
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Voit A, Patel V, Pachon R, Shah V, Bakhutma M, Kohlbrenner E, McArdle JJ, Dell'Italia LJ, Mendell JR, Xie LH, Hajjar RJ, Duan D, Fraidenraich D, Babu GJ. Reducing sarcolipin expression mitigates Duchenne muscular dystrophy and associated cardiomyopathy in mice. Nat Commun 2017; 8:1068. [PMID: 29051551 PMCID: PMC5648780 DOI: 10.1038/s41467-017-01146-7] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Accepted: 08/22/2017] [Indexed: 01/16/2023] Open
Abstract
Sarcolipin (SLN) is an inhibitor of the sarco/endoplasmic reticulum (SR) Ca2+ ATPase (SERCA) and is abnormally elevated in the muscle of Duchenne muscular dystrophy (DMD) patients and animal models. Here we show that reducing SLN levels ameliorates dystrophic pathology in the severe dystrophin/utrophin double mutant (mdx:utr -/-) mouse model of DMD. Germline inactivation of one allele of the SLN gene normalizes SLN expression, restores SERCA function, mitigates skeletal muscle and cardiac pathology, improves muscle regeneration, and extends the lifespan. To translate our findings into a therapeutic strategy, we knock down SLN expression in 1-month old mdx:utr -/- mice via adeno-associated virus (AAV) 9-mediated RNA interference. The AAV treatment markedly reduces SLN expression, attenuates muscle pathology and improves diaphragm, skeletal muscle and cardiac function. Taken together, our findings suggest that SLN reduction is a promising therapeutic approach for DMD.
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Affiliation(s)
- Antanina Voit
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, 07103, USA
| | - Vishwendra Patel
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, 07103, USA
| | - Ronald Pachon
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, 07103, USA
| | - Vikas Shah
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, 07103, USA
| | - Mohammad Bakhutma
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, 07103, USA
| | - Erik Kohlbrenner
- Cardiovascular Research Center, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Joseph J McArdle
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, 07103, USA
| | - Louis J Dell'Italia
- Department of Medicine, University of Alabama at Birmingham, and Birmingham VA Medical Center, Birmingham, AL, 35294, USA
| | - Jerry R Mendell
- Department of Pediatrics and Department of Neurology, Ohio State University Research Institute at Nationwide Children's Hospital, Columbus, OH, 43205, USA
| | - Lai-Hua Xie
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, 07103, USA
| | - Roger J Hajjar
- Cardiovascular Research Center, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Dongsheng Duan
- Department of Molecular Microbiology and Immunology, Neurology, Bioengineering, Biomedical Sciences, The University of Missouri, Columbia, MO, 65212, USA
| | - Diego Fraidenraich
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, 07103, USA
| | - Gopal J Babu
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, 07103, USA.
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14
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Matsuda T, Jeong JI, Ikeda S, Yamamoto T, Gao S, Babu GJ, Zhai P, Del Re DP. H-Ras Isoform Mediates Protection Against Pressure Overload-Induced Cardiac Dysfunction in Part Through Activation of AKT. Circ Heart Fail 2017; 10:CIRCHEARTFAILURE.116.003658. [PMID: 28193718 DOI: 10.1161/circheartfailure.116.003658] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Accepted: 01/11/2017] [Indexed: 11/16/2022]
Abstract
BACKGROUND In general, Ras proteins are thought to promote cardiac hypertrophy, an important risk factor for cardiovascular disease and heart failure. However, the contribution of different Ras isoforms has not been investigated. The objective of this study was to define the role of H- and K-Ras in modulating stress-induced myocardial hypertrophy and failure. METHODS AND RESULTS We used H- and K-Ras gene knockout mice and subjected them to pressure overload to induce cardiac hypertrophy and dysfunction. We observed a worsened cardiac phenotype in Hras-/- mice, while outcomes were improved in Kras+/- mice. We also used a neonatal rat cardiomyocyte culture system to elucidate the mechanisms underlying these observations. Our findings demonstrate that H-Ras, but not K-Ras, promotes cardiomyocyte hypertrophy both in vivo and in vitro. This response was mediated in part through the phosphoinositide 3-kinase-AKT signaling pathway. Adeno-associated virus-mediated increase in AKT activation improved the cardiac function in pressure overloaded Hras null hearts in vivo. These findings further support engagement of the phosphoinositide 3-kinase-AKT signaling axis by H-Ras. CONCLUSIONS Taken together, these findings indicate that H- and K-Ras have divergent effects on cardiac hypertrophy and heart failure in response to pressure overload stress.
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Affiliation(s)
- Takahisa Matsuda
- From the Cardiovascular Research Institute and the Department of Cell Biology and Molecular Medicine, Rutgers, New Jersey Medical School, Newark, NJ
| | - Jae Im Jeong
- From the Cardiovascular Research Institute and the Department of Cell Biology and Molecular Medicine, Rutgers, New Jersey Medical School, Newark, NJ
| | - Shohei Ikeda
- From the Cardiovascular Research Institute and the Department of Cell Biology and Molecular Medicine, Rutgers, New Jersey Medical School, Newark, NJ
| | - Takanobu Yamamoto
- From the Cardiovascular Research Institute and the Department of Cell Biology and Molecular Medicine, Rutgers, New Jersey Medical School, Newark, NJ
| | - Shumin Gao
- From the Cardiovascular Research Institute and the Department of Cell Biology and Molecular Medicine, Rutgers, New Jersey Medical School, Newark, NJ
| | - Gopal J Babu
- From the Cardiovascular Research Institute and the Department of Cell Biology and Molecular Medicine, Rutgers, New Jersey Medical School, Newark, NJ
| | - Peiyong Zhai
- From the Cardiovascular Research Institute and the Department of Cell Biology and Molecular Medicine, Rutgers, New Jersey Medical School, Newark, NJ
| | - Dominic P Del Re
- From the Cardiovascular Research Institute and the Department of Cell Biology and Molecular Medicine, Rutgers, New Jersey Medical School, Newark, NJ.
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15
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Shanmugam M, Li D, Gao S, Fefelova N, Shah V, Voit A, Pachon R, Yehia G, Xie LH, Babu GJ. Cardiac specific expression of threonine 5 to alanine mutant sarcolipin results in structural remodeling and diastolic dysfunction. PLoS One 2015; 10:e0115822. [PMID: 25671318 PMCID: PMC4324845 DOI: 10.1371/journal.pone.0115822] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Accepted: 12/02/2014] [Indexed: 12/23/2022] Open
Abstract
The functional importance of threonine 5 (T5) in modulating the activity of sarcolipin (SLN), a key regulator of sarco/endoplasmic reticulum (SR) Ca2+ ATPase (SERCA) pump was studied using a transgenic mouse model with cardiac specific expression of threonine 5 to alanine mutant SLN (SLNT5A). In these transgenic mice, the SLNT5A protein replaces the endogenous SLN in atria, while maintaining the total SLN content. The cardiac specific expression of SLNT5A results in severe cardiac structural remodeling accompanied by bi-atrial enlargement. Biochemical analyses reveal a selective downregulation of SR Ca2+ handling proteins and a reduced SR Ca2+ uptake both in atria and in the ventricles. Optical mapping analysis shows slower action potential propagation in the transgenic mice atria. Doppler echocardiography and hemodynamic measurements demonstrate a reduced atrial contractility and an impaired diastolic function. Together, these findings suggest that threonine 5 plays an important role in modulating SLN function in the heart. Furthermore, our studies suggest that alteration in SLN function can cause abnormal Ca2+ handling and subsequent cardiac remodeling and dysfunction.
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Affiliation(s)
- Mayilvahanan Shanmugam
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, New Jersey, United States of America
| | - Dan Li
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, New Jersey, United States of America
| | - Shumin Gao
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, New Jersey, United States of America
| | - Nadezhda Fefelova
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, New Jersey, United States of America
| | - Vikas Shah
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, New Jersey, United States of America
| | - Antanina Voit
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, New Jersey, United States of America
| | - Ronald Pachon
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, New Jersey, United States of America
| | - Ghassan Yehia
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, New Jersey, United States of America
| | - Lai-Hua Xie
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, New Jersey, United States of America
| | - Gopal J. Babu
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, New Jersey, United States of America
- * E-mail:
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16
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Zhao Z, Babu GJ, Wen H, Fefelova N, Gordan R, Sui X, Yan L, Vatner DE, Vatner SF, Xie LH. Overexpression of adenylyl cyclase type 5 (AC5) confers a proarrhythmic substrate to the heart. Am J Physiol Heart Circ Physiol 2014; 308:H240-9. [PMID: 25485900 DOI: 10.1152/ajpheart.00630.2014] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Inhibition of β-adrenergic receptor (β-AR) signaling is one of the most common therapeutic approaches for patients with arrhythmias. Adenylyl cyclase (AC) is the key enzyme responsible for transducing β-AR stimulation to increases in cAMP. The two major AC isoforms in the heart are types 5 and 6. Therefore, it is surprising that prior studies on overexpression of AC5 and AC6 in transgenic (Tg) mice have not examined mediation of arrhythmogenesis. Our goal was to examine the proarrhythmic substrate in AC5Tg hearts. Intracellular calcium ion (Ca(2+) i) was imaged in fluo-4 AM-loaded ventricular myocytes. The sarcoplasmic reticulum (SR) Ca(2+) content, fractional Ca(2+) release, and twitch Ca(2+) transient were significantly higher in the AC5Tg vs. wild-type (WT) myocytes, indicating Ca(2+) overload in AC5Tg myocytes. Action potential (AP) duration was significantly longer in AC5Tg than in WT myocytes. Additionally, AC5Tg myocytes developed spontaneous Ca(2+) waves in a larger fraction compared with WT myocytes, particularly when cells were exposed to isoproterenol. The Ca(2+) waves further induced afterdepolarizations and triggered APs. AC5Tg hearts had increased level of SERCA2a, oxidized Ca(2+)/calmodulin-dependent protein kinase II (CaMKII), and phosphorylation of ryanodine receptors (RyR) at the CaMKII site, especially after isoproterenol treatment. This was consistent with higher reactive oxygen species production in AC5Tg myocytes after isoproterenol treatment. Isoproterenol induced more severe arrhythmias in AC5Tg than in WT mice. We conclude that AC5 overexpression promotes arrhythmogenesis, by inducing SR Ca(2+) overload and hyperactivation of RyR (phosphorylation by CaMKII), which in turn induces spontaneous Ca(2+) waves and afterdepolarizations.
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Affiliation(s)
- Zhenghang Zhao
- Department of Pharmacology, School of Medicine, Xi'an Jiaotong University, Xi'an, People's Republic of China; Department of Cell Biology and Molecular Medicine, Rutgers University-New Jersey Medical School, Newark, New Jersey
| | - Gopal J Babu
- Department of Cell Biology and Molecular Medicine, Rutgers University-New Jersey Medical School, Newark, New Jersey
| | - Hairuo Wen
- Department of Cell Biology and Molecular Medicine, Rutgers University-New Jersey Medical School, Newark, New Jersey; Department of Reproductive and Genetic Toxicology, National Center for Safety Evaluation of Drugs, National Institutes for Food and Drug Control, Beijing, People's Republic of China; and
| | - Nadezhda Fefelova
- Department of Cell Biology and Molecular Medicine, Rutgers University-New Jersey Medical School, Newark, New Jersey
| | - Richard Gordan
- Department of Cell Biology and Molecular Medicine, Rutgers University-New Jersey Medical School, Newark, New Jersey
| | - Xiangzhen Sui
- Department of Cell Biology and Molecular Medicine, Rutgers University-New Jersey Medical School, Newark, New Jersey
| | - Lin Yan
- Department of Cell Biology and Molecular Medicine, Rutgers University-New Jersey Medical School, Newark, New Jersey
| | - Dorothy E Vatner
- Department of Cell Biology and Molecular Medicine, Rutgers University-New Jersey Medical School, Newark, New Jersey
| | - Stephen F Vatner
- Department of Cell Biology and Molecular Medicine, Rutgers University-New Jersey Medical School, Newark, New Jersey
| | - Lai-Hua Xie
- Department of Cell Biology and Molecular Medicine, Rutgers University-New Jersey Medical School, Newark, New Jersey; School of Pharmacology, Xinxiang Medical University, Xixiang, People's Republic of China
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17
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Patel V, Oh A, Voit A, Sultatos LG, Babu GJ, Wilson BA, Ho M, McArdle JJ. Altered active zones, vesicle pools, nerve terminal conductivity, and morphology during experimental MuSK myasthenia gravis. PLoS One 2014; 9:e110571. [PMID: 25438154 PMCID: PMC4249869 DOI: 10.1371/journal.pone.0110571] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Accepted: 09/15/2014] [Indexed: 11/18/2022] Open
Abstract
Recent studies demonstrate reduced motor-nerve function during autoimmune muscle-specific tyrosine kinase (MuSK) myasthenia gravis (MG). To further understand the basis of motor-nerve dysfunction during MuSK-MG, we immunized female C57/B6 mice with purified rat MuSK ectodomain. Nerve-muscle preparations were dissected and neuromuscular junctions (NMJs) studied electrophysiologically, morphologically, and biochemically. While all mice produced antibodies to MuSK, only 40% developed respiratory muscle weakness. In vitro study of respiratory nerve-muscle preparations isolated from these affected mice revealed that 78% of NMJs produced endplate currents (EPCs) with significantly reduced quantal content, although potentiation and depression at 50 Hz remained qualitatively normal. EPC and mEPC amplitude variability indicated significantly reduced number of vesicle-release sites (active zones) and reduced probability of vesicle release. The readily releasable vesicle pool size and the frequency of large amplitude mEPCs also declined. The remaining NMJs had intermittent (4%) or complete (18%) failure of neurotransmitter release in response to 50 Hz nerve stimulation, presumably due to blocked action potential entry into the nerve terminal, which may arise from nerve terminal swelling and thinning. Since MuSK-MG-affected muscles do not express the AChR γ subunit, the observed prolongation of EPC decay time was not due to inactivity-induced expression of embryonic acetylcholine receptor, but rather to reduced catalytic activity of acetylcholinesterase. Muscle protein levels of MuSK did not change. These findings provide novel insight into the pathophysiology of autoimmune MuSK-MG.
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MESH Headings
- Animals
- Female
- Immunization, Passive
- Mice
- Motor Endplate/pathology
- Motor Endplate/physiopathology
- Motor Neurons/pathology
- Myasthenia Gravis, Autoimmune, Experimental/immunology
- Myasthenia Gravis, Autoimmune, Experimental/metabolism
- Myasthenia Gravis, Autoimmune, Experimental/pathology
- Myasthenia Gravis, Autoimmune, Experimental/physiopathology
- Neural Conduction
- Neurotransmitter Agents/metabolism
- Protein Structure, Tertiary
- Rats
- Receptor Protein-Tyrosine Kinases/chemistry
- Receptor Protein-Tyrosine Kinases/immunology
- Receptors, Cholinergic/metabolism
- Synaptic Vesicles/metabolism
- Vaccination
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Affiliation(s)
- Vishwendra Patel
- Department of Pharmacology and Physiology, New Jersey Medical School-Rutgers University, Newark, New Jersey, United States of America
| | - Anne Oh
- Department of Pharmacology and Physiology, New Jersey Medical School-Rutgers University, Newark, New Jersey, United States of America
| | - Antanina Voit
- Department Cell Biology and Molecular Medicine, New Jersey Medical School-Rutgers University, Newark, New Jersey, United States of America
| | - Lester G. Sultatos
- Department of Pharmacology and Physiology, New Jersey Medical School-Rutgers University, Newark, New Jersey, United States of America
| | - Gopal J. Babu
- Department Cell Biology and Molecular Medicine, New Jersey Medical School-Rutgers University, Newark, New Jersey, United States of America
| | - Brenda A. Wilson
- Department of Microbiology, University of Illinois, Urbana-Champaign, Illinois, United States of America
| | - Mengfei Ho
- Department of Microbiology, University of Illinois, Urbana-Champaign, Illinois, United States of America
| | - Joseph J. McArdle
- Department of Pharmacology and Physiology, New Jersey Medical School-Rutgers University, Newark, New Jersey, United States of America
- * E-mail:
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18
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Zheng J, Yancey DM, Ahmed MI, Wei CC, Powell PC, Shanmugam M, Gupta H, Lloyd SG, McGiffin DC, Schiros CG, Denney TS, Babu GJ, Dell'Italia LJ. Increased sarcolipin expression and adrenergic drive in humans with preserved left ventricular ejection fraction and chronic isolated mitral regurgitation. Circ Heart Fail 2013; 7:194-202. [PMID: 24297688 DOI: 10.1161/circheartfailure.113.000519] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND There is currently no therapy proven to attenuate left ventricular (LV) dilatation and dysfunction in volume overload induced by isolated mitral regurgitation (MR). To better understand molecular signatures underlying isolated MR, we performed LV gene expression analyses and overlaid regulated genes into ingenuity pathway analysis in patients with isolated MR. METHODS AND RESULTS Gene arrays from LV tissue of 35 patients, taken at the time of surgical repair for isolated MR, were compared with 13 normal controls. Cine-MRI was performed in 31 patients before surgery to measure LV function and volume from serial short-axis summation. LV end-diastolic volume was 2-fold (P=0.005) higher in MR patients than in normal controls, and LV ejection fraction was 64±7% (50%-79%) in MR patients. Ingenuity pathway analysis identified significant activation of pathways involved in β-adrenergic, cAMP, and G-protein-coupled signaling, whereas there was downregulation of pathways associated with complement activation and acute phase response. SERCA2a and phospholamban protein were unchanged in MR versus control left ventricles. However, mRNA and protein levels of the sarcoplasmic reticulum Ca2+ ATPase (SERCA) regulatory protein sarcolipin, which is predominantly expressed in normal atria, were increased 12- and 6-fold, respectively. Immunofluorescence analysis confirmed the absence of sarcolipin in normal left ventricles and its marked upregulation in MR left ventricles. CONCLUSIONS These results demonstrate alterations in multiple pathways associated with β-adrenergic signaling and sarcolipin in the left ventricles of patients with isolated MR and LV ejection fraction>50%, suggesting a beneficial role for β-adrenergic blockade in isolated MR.
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19
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Gladden JD, Zelickson BR, Guichard JL, Ahmed MI, Yancey DM, Ballinger S, Shanmugam M, Babu GJ, Johnson MS, Darley-Usmar V, Dell'Italia LJ. Xanthine oxidase inhibition preserves left ventricular systolic but not diastolic function in cardiac volume overload. Am J Physiol Heart Circ Physiol 2013; 305:H1440-50. [PMID: 24014679 DOI: 10.1152/ajpheart.00007.2013] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Xanthine oxidase (XO) is increased in human and rat left ventricular (LV) myocytes with volume overload (VO) of mitral regurgitation and aortocaval fistula (ACF). In the setting of increased ATP demand, XO-mediated ROS can decrease mitochondrial respiration and contractile function. Thus, we tested the hypothesis that XO inhibition improves cardiomyocyte bioenergetics and LV function in chronic ACF in the rat. Sprague-Dawley rats were randomized to either sham or ACF ± allopurinol (100 mg·kg(-1)·day(-1), n ≥7 rats/group). Echocardiography at 8 wk demonstrated a similar 37% increase in LV end-diastolic dimension (P < 0.001), a twofold increase in LV end-diastolic pressure/wall stress (P < 0.05), and a twofold increase in lung weight (P < 0.05) in treated and untreated ACF groups versus the sham group. LV ejection fraction, velocity of circumferential shortening, maximal systolic elastance, and contractile efficiency were significantly depressed in ACF and significantly improved in ACF + allopurinol rats, all of which occurred in the absence of changes in the maximum O2 consumption rate measured in isolated cardiomyocytes using the extracellular flux analyzer. However, the improvement in contractile function is not paralleled by any attenuation in LV dilatation, LV end-diastolic pressure/wall stress, and lung weight. In conclusion, allopurinol improves LV contractile function and efficiency possibly by diminishing the known XO-mediated ROS effects on myofilament Ca(2+) sensitivity. However, LV remodeling and diastolic properties are not improved, which may explain the failure of XO inhibition to improve symptoms and hospitalizations in patients with severe heart failure.
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Affiliation(s)
- James D Gladden
- University of Alabama at Birmingham (UABComprehensive Cardiovascular Center, UAB Birmingham, Alabama
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20
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Schneider JS, Shanmugam M, Gonzalez JP, Lopez H, Gordan R, Fraidenraich D, Babu GJ. Increased sarcolipin expression and decreased sarco(endo)plasmic reticulum Ca2+ uptake in skeletal muscles of mouse models of Duchenne muscular dystrophy. J Muscle Res Cell Motil 2013; 34:349-56. [DOI: 10.1007/s10974-013-9350-0] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Accepted: 05/27/2013] [Indexed: 02/02/2023]
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21
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Huang Q, Babu GJ, Periasamy M, Eddinger TJ. SMB myosin heavy chain knockout enhances tonic contraction and reduces the rate of force generation in ileum and stomach antrum. Am J Physiol Cell Physiol 2012; 304:C194-206. [PMID: 23135699 DOI: 10.1152/ajpcell.00280.2012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The role of SMA and SMB smooth muscle myosin heavy chain (MHC) isoforms in tonic and phasic contractions was studied in phasic (longitudinal ileum and stomach circular antrum) and tonic (stomach circular fundus) smooth muscle tissues of SMB knockout mice. Knocking out the SMB MHC gene eliminated SMB MHC protein expression and resulted in upregulation of the SMA MHC protein without altering the total MHC protein level. Switching from SMB to SMA MHC protein expression decreased the rate of the force transient and increased the sustained tonic force in SMB((-/-)) ileum and antrum with high potassium (KPSS) but not with carbachol (CCh) stimulation. The increased tonic contraction under the depolarized condition was not through changes in second messenger signaling pathways (PKC/CPI-17 or Rho/ROCK signaling pathway) or LC(20) phosphorylation. Biochemical analyses showed that the expression of contractile regulatory proteins (MLCK, MLCP, PKCδ, and CPI-17) did not change significantly in tissues tested except for PKCα protein expression being significantly decreased in the SMB((-/-)) antrum. However, specifically activating PKCα with phorbol dibutyrate (PDBu) was not significantly different in knockout and wild-type tissues, with total force being a fraction of the force generation with KPSS or CCh stimulation in SMB((-/-)) ileum and antrum. Taken together, these data show removing the SMB MHC protein expression with a compensatory increase in the SMA MHC protein results in enhanced sustained KPSS-induced tonic contraction with a reduced rate of force generation in these phasic tissues.
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Affiliation(s)
- Qian Huang
- Department of Biological Sciences, Marquette University, Milwaukee, WI, 53201, USA
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22
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Xie LH, Shanmugam M, Park JY, Zhao Z, Wen H, Tian B, Periasamy M, Babu GJ. Ablation of sarcolipin results in atrial remodeling. Am J Physiol Cell Physiol 2012; 302:C1762-71. [PMID: 22496245 DOI: 10.1152/ajpcell.00425.2011] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Sarcolipin (SLN) is a key regulator of sarco(endo)plasmic reticulum (SR) Ca(2+)-ATPase (SERCA), and its expression is altered in diseased atrial myocardium. To determine the precise role of SLN in atrial Ca(2+) homeostasis, we developed a SLN knockout (sln-/-) mouse model and demonstrated that ablation of SLN enhances atrial SERCA pump activity. The present study is designed to determine the long-term effects of enhanced SERCA activity on atrial remodeling in the sln-/- mice. Calcium transient measurements show an increase in atrial SR Ca(2+) load and twitch Ca(2+) transients. Patch-clamping experiments demonstrate activation of the forward mode of sodium/calcium exchanger, increased L-type Ca(2+) channel activity, and prolongation of action potential duration at 90% repolarization in the atrial myocytes of sln-/- mice. Spontaneous Ca(2+) waves, delayed afterdepolarization, and triggered activities are frequent in the atrial myocytes of sln-/- mice. Furthermore, loss of SLN in atria is associated with increased interstitial fibrosis and altered expression of genes encoding collagen and other extracellular matrix proteins. Our results also show that the sln-/- mice are susceptible to atrial arrhythmias upon aging. Together, these findings indicate that ablation of SLN results in increased SERCA activity and SR Ca(2+) load, which, in turn, could cause abnormal intracellular Ca(2+) handling and atrial remodeling.
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Affiliation(s)
- Lai-Hua Xie
- Department of Cell Biology and Molecular Medicine, University of Medicine and Dentistry of New Jersey-New Jersey Medical School, Newark, 07103, USA
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23
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Tupling AR, Bombardier E, Gupta SC, Hussain D, Vigna C, Bloemberg D, Quadrilatero J, Trivieri MG, Babu GJ, Backx PH, Periasamy M, MacLennan DH, Gramolini AO. Enhanced Ca2+ transport and muscle relaxation in skeletal muscle from sarcolipin-null mice. Am J Physiol Cell Physiol 2011; 301:C841-9. [PMID: 21697544 DOI: 10.1152/ajpcell.00409.2010] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Sarcolipin (SLN) inhibits sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA) pumps. To evaluate the physiological significance of SLN in skeletal muscle, we compared muscle contractility and SERCA activity between Sln-null and wild-type mice. SLN protein expression in wild-type mice was abundant in soleus and red gastrocnemius (RG), low in extensor digitorum longus (EDL), and absent from white gastrocnemius (WG). SERCA activity rates were increased in soleus and RG, but not in EDL or WG, from Sln-null muscles, compared with wild type. No differences were seen between wild-type and Sln-null EDL muscles in force-frequency curves or maximum rates of force development (+dF/dt). Maximum relaxation rates (-dF/dt) of EDL were higher in Sln-null than wild type across a range of submaximal stimulation frequencies, but not during a twitch or peak tetanic contraction. For soleus, no differences were seen between wild type and Sln-null in peak tetanic force or +dF/dt; however, force-frequency curves showed that peak force during a twitch and 10-Hz contraction was lower in Sln-null. Changes in the soleus force-frequency curve corresponded with faster rates of force relaxation at nearly all stimulation frequencies in Sln-null compared with wild type. Repeated tetanic stimulation of soleus caused increased (-dF/dt) in wild type, but not in Sln-null. No compensatory responses were detected in analysis of other Ca(2+) regulatory proteins using Western blotting and immunohistochemistry or myosin heavy chain expression using immunofluorescence. These results show that 1) SLN regulates Ca(2+)-ATPase activity thereby regulating contractile kinetics in at least some skeletal muscles, 2) the functional significance of SLN is graded to the endogenous SLN expression level, and 3) SLN inhibitory effects on SERCA function are relieved in response to repeated contractions thus enhancing relaxation rates.
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24
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Zhao Z, Fefelova N, Shanmugam M, Bishara P, Babu GJ, Xie LH. Angiotensin II induces afterdepolarizations via reactive oxygen species and calmodulin kinase II signaling. J Mol Cell Cardiol 2010; 50:128-36. [PMID: 21059353 DOI: 10.1016/j.yjmcc.2010.11.001] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2010] [Revised: 10/02/2010] [Accepted: 11/01/2010] [Indexed: 12/13/2022]
Abstract
Renin-angiotensin system inhibitors significantly reduce the incidence of arrhythmias. However, the underlying mechanism(s) is not well understood. We aim to test the hypothesis that angiotensin II (Ang II) induces early afterdepolarizations (EADs) and triggered activities (TAs) via the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase-ROS-calmodulin kinase II (CaMKII) pathway. ROS production was analyzed in the isolated rabbit myocytes loaded with ROS dye. Ang II (1-2 μM) increased ROS fluorescence in myocytes, which was abolished by Ang II type 1 receptor blocker losartan, NADPH oxidase inhibitor apocynin, and antioxidant MnTMPyP, respectively. Action potentials were recorded using the perforated patch-clamp technique. EADs emerged in 27 out of 41 (66%) cells at 15.8 ± 1.6 min after Ang II (1-2 μM) perfusion. Ang II-induced EADs were eliminated by losartan, apocynin, or trolox. The CaMKII inhibitor KN-93 (n=6) and inhibitory peptide (AIP) (n=4) also suppressed Ang II-induced EADs, whereas the inactive analogue KN-92 did not. Nifedipine, a blocker of L-type Ca current (I(Ca)(2+)(,L)), or ranolazine, an inhibitor of late Na current (I(Na)(+)), abolished Ang II-induced EADs. The effects of Ang II on major membrane currents were evaluated using voltage clamp. While Ang II at same concentrations had no significant effect on total outward K(+) current, it enhanced I(Ca.L) and late I(Na), which were attenuated by losartan, apocynin, trolox, or KN-93. We conclude that Ang II induces EADs via intracellular ROS production through NADPH oxidase, activation of CaMKII, and enhancement of I(Ca,L) and late I(Na). These results provide evidence supporting a link between renin-angiotensin system and cardiac arrhythmias.
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Affiliation(s)
- Zhenghang Zhao
- Department of Cell Biology and Molecular Medicine, UMDNJ-New Jersey Medical School, Newark, NJ 07101, USA
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25
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Shanmugam M, Gao S, Hong C, Fefelova N, Nowycky MC, Xie LH, Periasamy M, Babu GJ. Ablation of phospholamban and sarcolipin results in cardiac hypertrophy and decreased cardiac contractility. Cardiovasc Res 2010; 89:353-61. [PMID: 20833651 DOI: 10.1093/cvr/cvq294] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
AIMS Improving the sarco(endo)plasmic reticulum (SR) Ca(2+)-ATPase (SERCA) function has clinical implications in treating heart failure. The present study aimed to determine the effect of constitutive activation of the SERCA pump on cardiac contractility in normal mice and during pressure-overload-induced cardiac hypertrophy. METHODS AND RESULTS The SERCA pump was constitutively activated in both atrial and ventricular chambers of the mouse heart by ablating its key regulators, phospholamban (PLN) and sarcolipin (SLN). The double-knockout (dKO) mice for PLN and SLN showed increased SERCA pump activity, Ca(2+) transients and SR Ca(2+) load, and developed cardiac hypertrophy. Echocardiographic measurements showed that the basal cardiac function was not affected in the young dKO mice. However, the cardiac function worsened upon ageing and when subjected to pressure overload. CONCLUSION Our studies suggest that the constitutive activation of the SERCA pump is detrimental to cardiac function. Our findings also emphasize the need for dynamic regulation of the SERCA pump by PLN and/or SLN to maintain cardiac contractility in normal conditions and during pathophysiological states.
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Affiliation(s)
- Mayilvahanan Shanmugam
- Department of Cell Biology and Molecular Medicine, University of Medicine and Dentistry of New Jersey-New Jersey Medical School, 185 South Orange Avenue, MSB, G609, Newark, NJ 07103, USA
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26
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Hypolite JA, Chang S, LaBelle E, Babu GJ, Periasamy M, Wein AJ, Chacko S. Deletion of SM-B, the high ATPase isoform of myosin, upregulates the PKC-mediated signal transduction pathway in murine urinary bladder smooth muscle. Am J Physiol Renal Physiol 2008; 296:F658-65. [PMID: 19052105 DOI: 10.1152/ajprenal.90221.2008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Detrusor smooth muscle (DSM) hypertrophy induced by partial bladder outlet obstruction (PBOO) is associated with changes in the NH2-terminal myosin heavy chain isoform from predominantly SM-B to SM-A, alteration in the Ca2+ sensitization pathway, and the contractile characteristics from phasic to tonic in rabbits. We utilized the SM-B knockout (KO) mouse to determine whether a shift from SM-B to SM-A without PBOO is associated with changes in the signal transduction pathway mediated via PKC and CPI-17, which keeps the myosin phosphorylation (MLC20) level high by inhibiting the myosin phosphatase. DSM strips from SM-B KO mice generated more force in response to electrical field stimulation, KCl, carbachol, and phorbol 12,13-dibutyrate than that of age-matched wild-type mice. There was no difference in the ED50 for carbachol but the maximum response was greater for the SM-B KO mice. DSM from SM-B KO mice revealed increased mass and hypertrophy. The KO mice also showed an overexpression of PKC-alpha, increased levels of phospho-CPI-17, and an elevated level of IP3 and DAG upon stimulation with carbachol. Two-dimensional gel electrophoresis revealed an increased level of MLC20 phosphorylation in response to carbachol. Together, these changes may be responsible for the higher level of force generation and maintenance by the DSM from the SM-B KO bladders. In conclusion, our data show that ablation of SM-B is associated with alteration of PKC-mediated signal transduction and CPI-17-mediated Ca2+ sensitization pathway that regulate smooth muscle contraction. Interestingly, similar changes are also present in PBOO-induced DSM compensatory response in the rabbit model in which SM-B is downregulated.
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Affiliation(s)
- Joseph A Hypolite
- Division of Urology and Department of Pathobiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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27
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Ottenheijm CAC, Fong C, Vangheluwe P, Wuytack F, Babu GJ, Periasamy M, Witt CC, Labeit S, Granzier H. Sarcoplasmic reticulum calcium uptake and speed of relaxation are depressed in nebulin-free skeletal muscle. FASEB J 2008; 22:2912-9. [PMID: 18434434 DOI: 10.1096/fj.07-104372] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Previous work suggested that altered Ca(2+) homeostasis might contribute to dysfunction of nebulin-free muscle, as gene expression analysis revealed that the sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA)-inhibitor sarcolipin (SLN) is up-regulated >70-fold in nebulin knockout mice, and here we tested this proposal. We investigated SLN protein expression in nebulin-free and wild-type skeletal muscle, as well as expression of other Ca(2+)-handling proteins. Ca(2+) uptake capacity was determined in isolated sarcoplasmic reticulum vesicles and in intact myofibers by measuring Ca(2+) transients. Muscle contractile performance was determined in skinned muscle activated with exogenous Ca(2+), as well as in electrically stimulated intact muscle. We found profound up-regulation of SLN protein in nebulin-free skeletal muscle, whereas expression of other Ca(2+)-handling proteins was not (calsequestrin and phospholamban) or was minimally (SERCA) affected. Speed of Ca(2+) uptake was >3-fold decreased in sarcoplasmic reticulum vesicles isolated from nebulin-free muscle as well as in nebulin-free intact myofibers. Ca(2+)-activated stress in skinned muscle and stress produced by intact nebulin-free muscle were reduced to a similar extent compared with wild type. Half-relaxation time was significantly longer in nebulin-free compared with wild-type muscle. Thus, the present study demonstrates for the first time that nebulin might also be involved in physiological Ca(2+) handling of the SR-myofibrillar system.
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Affiliation(s)
- Coen A C Ottenheijm
- Dept. of Molecular and Cellular Biology, University of Arizona, PO Box 245217, Tucson, AZ 85724, USA
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28
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Tupling AR, Hussain D, Trivieri MG, Babu GJ, Backx PH, Periasamy M, MacLennan DH, Gramolini AO. Improvement of Ca
2+
Transport and Muscle Relaxation in Skeletal Muscle From Sarcolipin Null Mice. FASEB J 2008. [DOI: 10.1096/fasebj.22.1_supplement.962.34] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | - Dawar Hussain
- Banting and Best Department of Medical ResearchUniversity of TorontoToronto, 0Canada
| | | | - Gopal J Babu
- Department of Physiology and Cell BiologyOhio State UniversityColumbusOH
| | - Peter H. Backx
- Department of PhysiologyUniversity of TorontoTorontoCanada
| | - Muthu Periasamy
- Department of Physiology and Cell BiologyOhio State UniversityColumbusOH
| | - David H. MacLennan
- Banting and Best Department of Medical ResearchUniversity of TorontoToronto, 0Canada
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29
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Periasamy M, Bhupathy P, Babu GJ. Regulation of sarcoplasmic reticulum Ca2+ ATPase pump expression and its relevance to cardiac muscle physiology and pathology. Cardiovasc Res 2007; 77:265-73. [PMID: 18006443 DOI: 10.1093/cvr/cvm056] [Citation(s) in RCA: 177] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Cardiac sarcoplasmic reticulum (SR) Ca(2+) ATPase (SERCA2a) plays a central role in myocardial contractility. SERCA2a actively transports Ca(2+) into the SR and regulates cytosolic Ca(2+) concentration, SR Ca(2+) load, and the rate of contraction and relaxation of the heart. In the heart, SERCA pump activity is regulated by two small molecular weight proteins: phospholamban (PLB) and sarcolipin (SLN). Decreases in the expression levels of SERCA2a have been observed in a variety of pathological conditions. In addition, altered expression of PLB and SLN has been reported in many cardiac diseases. Thus, SERCA2a is a major regulator of intracellular Ca(2+) homeostasis, and changes in the expression and activity of the SERCA pump contribute to the decreased SR Ca(2+) content and cardiac dysfunction during pathogenesis. In this review, we discuss the mechanisms controlling SERCA pump expression and activity both during normal physiology and under pathological states.
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Affiliation(s)
- Muthu Periasamy
- Department of Physiology and Cell Biology, College of Medicine and Public Health, The Ohio State University, 304 Hamilton Hall, 1645 Neil Ave, Columbus, OH 43210, USA.
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30
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Iyengar S, Haas G, Lamba S, Orsinelli DA, Babu GJ, Ferketich AK, Yamokoski L, Periasamy M, Abraham WT. Effect of cardiac resynchronization therapy on myocardial gene expression in patients with nonischemic dilated cardiomyopathy. J Card Fail 2007; 13:304-11. [PMID: 17517351 DOI: 10.1016/j.cardfail.2007.01.005] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2006] [Revised: 11/28/2006] [Accepted: 01/24/2007] [Indexed: 11/20/2022]
Abstract
BACKGROUND Cardiac resynchronization therapy (CRT) improves echocardiographic measures of ventricular structure and function in the failing heart. To determine whether or not these changes are representative of true biologic reverse ventricular remodeling or simply an artifact of an improved contraction pattern, we evaluated changes in myocardial gene expression typical of reverse remodeling before and after chronic CRT. METHODS AND RESULTS Optimally medically treated patients with nonischemic heart failure meeting standard clinical criteria for CRT were enrolled. Before implantation of a CRT device, baseline echocardiogram and endomyocardial biopsies were obtained. These studies were repeated after 6 months of CRT. Using quantitative reverse-transcriptase polymerase chain reaction, the amount of messenger RNA for selected genes regulating contractile function (sarcoplasmic reticulum Ca2+ ATPase, alpha- and beta-myosin heavy chain [MHC] isoforms, phospholamban [PLB]), and pathologic hypertrophy (beta-MHC and atrial natriuretic peptide [ANP]) was determined from biopsy samples. Changes in gene expression (baseline to 6 months) were determined and correlated to changes in echocardiographic remodeling parameters. Ten patients were enrolled in the study, with 7 completing both baseline and follow-up biopsies and echocardiograms. On average, a significant increase was observed in alpha-MHC and PLB gene expression from baseline to 6 months (P = .016 for both). Beta-MHC levels tended to decrease with CRT (P = .078). Increased alpha-MHC levels correlated best with decreases in left ventricular end-diastolic dimension (P = .073, r = -0.71) and reductions in mitral regurgitation. No significant correlation between ejection fraction and gene expression was found. CONCLUSIONS These changes in myocardial gene expression support the occurrence of reverse remodeling during chronic CRT. The changes are similar to those reported previously with beta-blockade, but were seen on top of standard drug therapies for heart failure.
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Affiliation(s)
- Srinivas Iyengar
- Division of Cardiovascular Medicine and the Department of Internal Medicine, The Ohio State University, Columbus, Ohio 43210-1252, USA
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31
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Talukder MAH, Kalyanasundaram A, Zhao X, Zuo L, Bhupathy P, Babu GJ, Cardounel AJ, Periasamy M, Zweier JL. Expression of SERCA isoform with faster Ca2+ transport properties improves postischemic cardiac function and Ca2+ handling and decreases myocardial infarction. Am J Physiol Heart Circ Physiol 2007; 293:H2418-28. [PMID: 17630344 DOI: 10.1152/ajpheart.00663.2007] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Myocardial ischemia-reperfusion (I/R) injury is associated with contractile dysfunction, arrhythmias, and myocyte death. Intracellular Ca(2+) overload with reduced activity of sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA) is a critical mechanism of this injury. Although upregulation of SERCA function is well documented to improve postischemic cardiac function, there are conflicting reports where pharmacological inhibition of SERCA improved postischemic function. SERCA2a is the primary cardiac isoform regulating intracellular Ca(2+) homeostasis; however, SERCA1a has been shown to substitute SERCA2a with faster Ca(2+) transport kinetics. Therefore, to further address this issue and to evaluate whether SERCA1a expression could improve postischemic cardiac function and myocardial salvage, in vitro and in vivo myocardial I/R studies were performed on SERCA1a transgenic (SERCA1a(+/+)) and nontransgenic (NTG) mice. Langendorff-perfused hearts were subjected to 30 min of global ischemia followed by reperfusion. Baseline preischemic coronary flow and left ventricular developed pressure were significantly greater in SERCA1a(+/+) mice compared with NTG mice. Independent of reperfusion-induced oxidative stress, SERCA1a(+/+) hearts demonstrated greatly improved postischemic (45 min) contractile recovery with less persistent arrhythmias compared with NTG hearts. Morphometry showed better-preserved myocardial structure with less infarction, and electron microscopy demonstrated better-preserved myofibrillar and mitochondrial ultrastructure in SERCA1a(+/+) hearts. Importantly, intraischemic Ca(2+) levels were significantly lower in SERCA1a(+/+) hearts. The cardioprotective effect of SERCA1a was also observed during in vivo regional I/R with reduced myocardial infarct size after 24 h of reperfusion. Thus SERCA1a(+/+) hearts were markedly protected against I/R injury, suggesting that expression of SERCA 1a isoform reduces postischemic Ca(2+) overload and thus provides potent myocardial protection.
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MESH Headings
- Animals
- Arrhythmias, Cardiac/etiology
- Arrhythmias, Cardiac/metabolism
- Arrhythmias, Cardiac/physiopathology
- Arrhythmias, Cardiac/prevention & control
- Calcium/metabolism
- Coronary Circulation
- Disease Models, Animal
- Electron Spin Resonance Spectroscopy
- Fluorescent Dyes
- Free Radicals/metabolism
- Heterocyclic Compounds, 3-Ring
- Immunohistochemistry
- Isoenzymes/metabolism
- Mice
- Mice, Transgenic
- Mitochondria, Heart/metabolism
- Mitochondria, Heart/ultrastructure
- Myocardial Contraction
- Myocardial Infarction/etiology
- Myocardial Infarction/genetics
- Myocardial Infarction/metabolism
- Myocardial Infarction/physiopathology
- Myocardial Infarction/prevention & control
- Myocardial Reperfusion Injury/complications
- Myocardial Reperfusion Injury/genetics
- Myocardial Reperfusion Injury/metabolism
- Myocardial Reperfusion Injury/physiopathology
- Myocardial Reperfusion Injury/prevention & control
- Myocardium/enzymology
- Myocardium/metabolism
- Myocardium/ultrastructure
- Sarcoplasmic Reticulum/enzymology
- Sarcoplasmic Reticulum/metabolism
- Sarcoplasmic Reticulum Calcium-Transporting ATPases/genetics
- Sarcoplasmic Reticulum Calcium-Transporting ATPases/metabolism
- Spectrometry, Fluorescence/methods
- Time Factors
- Tyrosine/analogs & derivatives
- Tyrosine/metabolism
- Ventricular Function, Left
- Ventricular Pressure
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Affiliation(s)
- M A Hassan Talukder
- Davis Heart and Lung Research Institute and Division of Cardiovascular Medicine, Department of Internal Medicine, The Ohio State University College of Medicine and Public Health, Columbus, Ohio 43210, USA
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Babu GJ, Bhupathy P, Carnes CA, Billman GE, Periasamy M. Differential expression of sarcolipin protein during muscle development and cardiac pathophysiology. J Mol Cell Cardiol 2007; 43:215-22. [PMID: 17561107 PMCID: PMC2706541 DOI: 10.1016/j.yjmcc.2007.05.009] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2007] [Revised: 05/02/2007] [Accepted: 05/10/2007] [Indexed: 11/23/2022]
Abstract
Sarcolipin (SLN) is a small molecular weight sarcoplasmic reticulum (SR) membrane protein expressed both in cardiac and skeletal muscle tissues. Recent studies using transgenic mouse models have demonstrated that SLN is an important regulator of cardiac SR Ca2+ ATPase 2a (SERCA2a). However, there is a paucity of information regarding the SLN protein expression in small versus larger mammals and its regulation during development and cardiac pathophysiology. Therefore, the major goal of this study was to generate an SLN specific antibody and perform detailed analyses of SLN protein expression during muscle development and in the diseased myocardium. The important findings of the present study are: (i) in small mammals, SLN expression is predominant in the atria but low in the ventricle and in skeletal muscle tissues, whereas in large mammals, SLN is quite abundant in skeletal muscle tissues than the atria, (ii) SLN and SERCA2a are co-expressed in all striated muscle tissues studied except ventricle and co-ordinately regulated during muscle development and (iii) SLN protein levels are approximately 3 fold upregulated in the atria of heart failure dogs and approximately 30% decreased in the atria of hearts prone to myocardial ischemia. In addition we found that in the phospholamban null atria, SLN protein levels are upregulated.
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Affiliation(s)
- Gopal J Babu
- Department of Physiology and Cell Biology, The Ohio State University Medical Center, Columbus, Ohio 43210
| | - Poornima Bhupathy
- Department of Physiology and Cell Biology, The Ohio State University Medical Center, Columbus, Ohio 43210
| | - Cynthia A Carnes
- College of Pharmacy, The Ohio State University, Columbus, Ohio 43210
| | - George E Billman
- Department of Physiology and Cell Biology, The Ohio State University Medical Center, Columbus, Ohio 43210
| | - Muthu Periasamy
- Department of Physiology and Cell Biology, The Ohio State University Medical Center, Columbus, Ohio 43210
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Talukder MH, Chen C, Kalyanasundaram A, Bhupathy P, Babu GJ, Periasamy M, Zweier JL. Glutathiolation and Nitration of Sarcoplasmic Reticulum Ca
2+
‐ATPase (SERCA) in hearts overexpressing SERCA1a‐pump. FASEB J 2007. [DOI: 10.1096/fasebj.21.5.a535-c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- M.A. Hassan Talukder
- Davis Heart and Lung Research Institute, The Ohio State University473 West 12th AvenueColumbusOH43210
| | - Chun‐An Chen
- Davis Heart and Lung Research Institute, The Ohio State University473 West 12th AvenueColumbusOH43210
| | - Anuradha Kalyanasundaram
- Department of Physiology and Cell BiologyThe Ohio State University1645 Neil AvenueColumbusOH43210
| | - Poornima Bhupathy
- Department of Physiology and Cell BiologyThe Ohio State University1645 Neil AvenueColumbusOH43210
| | - Gopal J. Babu
- Department of Physiology and Cell BiologyThe Ohio State University1645 Neil AvenueColumbusOH43210
| | - Muthu Periasamy
- Department of Physiology and Cell BiologyThe Ohio State University1645 Neil AvenueColumbusOH43210
| | - Jay L. Zweier
- Davis Heart and Lung Research Institute, The Ohio State University473 West 12th AvenueColumbusOH43210
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Bhupathy P, Babu GJ, Periasamy M. Sarcolipin and phospholamban as regulators of cardiac sarcoplasmic reticulum Ca2+ ATPase. J Mol Cell Cardiol 2007; 42:903-11. [PMID: 17442337 PMCID: PMC2743185 DOI: 10.1016/j.yjmcc.2007.03.738] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2006] [Revised: 02/15/2007] [Accepted: 03/02/2007] [Indexed: 01/26/2023]
Abstract
The cardiac sarcoplasmic reticulum calcium ATPase (SERCA2a) plays a critical role in maintaining the intracellular calcium homeostasis during cardiac contraction and relaxation. It has been well documented over the years that altered expression and activity of SERCA2a can lead to systolic and diastolic dysfunction. The activity of SERCA2a is regulated by two structurally similar proteins, phospholamban (PLB) and sarcolipin (SLN). Although, the relevance of PLB has been extensively studied over the years, the role SLN in cardiac physiology is an emerging field of study. This review focuses on the advances in the understanding of the regulation of SERCA2a by SLN and PLB. In particular, it highlights the similarities and differences between the two proteins and their roles in cardiac patho-physiology.
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Affiliation(s)
| | | | - Muthu Periasamy
- Corresponding Author: Address- 304 Hamilton Hall, 1645 Neil Avenue, Columbus OH, 43210, USA, Phone # 614-292-2310, Fax # 614-292-4888,
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Babu GJ, Celia G, Rhee AY, Yamamura H, Takahashi K, Brozovich FV, Osol G, Periasamy M. Effects of h1-calponin ablation on the contractile properties of bladder versus vascular smooth muscle in mice lacking SM-B myosin. J Physiol 2006; 577:1033-42. [PMID: 16973711 PMCID: PMC1890375 DOI: 10.1113/jphysiol.2006.118828] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2006] [Accepted: 09/07/2006] [Indexed: 12/28/2022] Open
Abstract
The functional significance of smooth muscle-specific h1-calponin up-regulation in the smooth muscle contractility of SM-B null mice was studied by generating double knockout mice lacking both h1-calponin and SM-B myosin. The double knockout mice appear healthy, reproduce well and do not show any smooth muscle pathology. Loss of h1-calponin in the SM-B null mice bladder resulted in increased maximal shortening velocity (V(max)) and steady-state force generation. The force dilatation pressure, which was decreased in the SM-B null mesenteric vessels, was restored to wild-type levels in the double knockout vessels. In contrast, the half-time to maximal constriction was significantly increased in the double knockout vessels similar to that of SM-B null mice and indicating decreased shortening velocity in the double knockout vessels. Biochemical analyses showed that there is a significant reduction in smooth muscle alpha-actin levels, whereas h-caldesmon levels are increased in the double knockout bladder and mesenteric vessels, suggesting that these changes may also partly contribute to the altered contractile function. Taken together, our studies suggest that up-regulation of h1-calponin in the SM-B null mice may be necessary to maintain a reduced level of cross-bridge cycling over time in the absence of SM-B myosin and play an important role in regulating the smooth muscle contraction.
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Affiliation(s)
- Gopal J Babu
- Department of Physiology and Cell Biology, The Ohio State University College of Medicine and Public Health, 304 Hamilton Hall, 1645 Neil Avenue, Columbus, OH 43210, USA.
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Babu GJ, Bhupathy P, Petrashevskaya NN, Wang H, Raman S, Wheeler D, Jagatheesan G, Wieczorek D, Schwartz A, Janssen PML, Ziolo MT, Periasamy M. Targeted Overexpression of Sarcolipin in the Mouse Heart Decreases Sarcoplasmic Reticulum Calcium Transport and Cardiac Contractility. J Biol Chem 2006; 281:3972-9. [PMID: 16365042 DOI: 10.1074/jbc.m508998200] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The role of sarcolipin (SLN) in cardiac physiology was critically evaluated by generating a transgenic (TG) mouse model in which the SLN to sarco(endoplasmic)reticulum (SR) Ca(2+) ATPase (SERCA) ratio was increased in the ventricle. Overexpression of SLN decreases SR calcium transport function and results in decreased calcium transient amplitude and rate of relaxation. SLN TG hearts exhibit a significant decrease in rates of contraction and relaxation when assessed by ex vivo work-performing heart preparations. Similar results were also observed with muscle preparations and myocytes from SLN TG ventricles. Interestingly, the inhibitory effect of SLN was partially relieved upon high dose of isoproterenol treatment and stimulation at high frequency. Biochemical analyses show that an increase in SLN level does not affect PLB levels, monomer to pentamer ratio, or its phosphorylation status. No compensatory changes were seen in the expression of other calcium-handling proteins. These studies suggest that the SLN effect on SERCA pump is direct and is not mediated through increased monomerization of PLB or by a change in PLB phosphorylation status. We conclude that SLN is a novel regulator of SERCA pump activity, and its inhibitory effect can be reversed by beta-adrenergic agonists.
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Affiliation(s)
- Gopal J Babu
- Department of Physiology and Cell Biology, The Ohio State University College of Medicine and Public Health, Columbus, 43210, USA
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Patzak A, Petzhold D, Wronski T, Martinka P, Babu GJ, Periasamy M, Haase H, Morano I. Constriction velocities of renal afferent and efferent arterioles of mice are not related to SMB expression. Kidney Int 2005; 68:2726-34. [PMID: 16316347 DOI: 10.1111/j.1523-1755.2005.00743.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
BACKGROUND Constriction of renal arterioles contributes significantly to the control of perfusion and glomerular filtration. Afferent but not efferent arterioles express smooth muscle myosin heavy chain B (SMB) (with a 5'-insert of seven amino acids). The aim of the present study was to investigate (1) the constriction characteristics of afferent and efferent arterioles under physiologic load and (2) whether expression of SMB may causally contribute to these constriction characteristics. METHODS We compared constriction parameters [constriction amplitude, maximal rate of constriction velocity ("dc/dt(max)"), and time to half-maximal constriction (t(1/2)) of in vitro perfused renal afferent and efferent arterioles of wild-type (smb(+/+)] and homozygous SMB knockout [smb(-/-)] mice upon stimulation with angiotensin II (Ang II) (10(-8) mol/L) and potassium chloride (KCl) (100 mmol/L). SMB expression was investigated by double-labeling immunofluorescence. RESULTS Contraction amplitude and dc/dt(max) of mouse afferent arterioles upon Ang II stimulation were significantly greater compared to efferent arterioles. However, constriction amplitudes, dc/dt(max), and t(1/2) of afferent as well as efferent arterioles upon Ang II stimulation were similar in smb(+/+) and smb(-/-) mice. Constriction amplitudes upon KCl stimulation of afferent arterioles were similar in both smb(+/+) and smb(-/-) mice. Furthermore, KCl-induced dc/dt(max) and t(1/2) of afferent arterioles were similar in both smb(+/+) and smb(-/-) mice. SMB expression could be detected in afferent but not efferent arterioles in smb(+/+) mice. No SMB expression in either arteriole could be observed in smb(-/-) mice. CONCLUSION Our results suggest that the presence of different alternatively 5'-spliced smooth muscle-myosin heavy chain (SM-MHC) isoforms does not dominate the different contractile features of physiologically loaded renal afferent or efferent arterioles.
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Affiliation(s)
- Andreas Patzak
- University Medicine Charité, Johannes-Müller-Institute for Physiology, Berlin, Germany
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38
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Abstract
The sarcoplasmic reticulum Ca2+ ATPase (SERCA) plays a pivotal role in calcium cycling and the beat-to-beat function of the heart. Recent studies have shown that decreased expression and activity of SERCA are associated with end-stage heart failure in humans and in experimental animal models of heart failure. There has been considerable controversy over whether a decrease in SERCA level is a cause or effect of hypertrophy. To address directly whether alterations in SERCA levels modify calcium homeostasis and heart function, we have chosen to alter the SERCA protein expression genetically using transgenic and gene-targeted knockout mouse technology. This chapter describes the methodology for generation of mouse models that overexpress different SERCA isoforms and a SERCA2 knockout mouse model with decreased SERCA levels.
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Affiliation(s)
- Gopal J Babu
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH, USA
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Karagiannis P, Babu GJ, Periasamy M, Brozovich FV. Myosin heavy chain isoform expression regulates shortening velocity in smooth muscle: studies using an SMB KO mouse line. J Muscle Res Cell Motil 2005; 25:149-58. [PMID: 15360130 DOI: 10.1023/b:jure.0000035879.87045.4b] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The kinetics of smooth muscle are thought to be partially determined by the level of the expression of the 7 amino acid insert, SMB, in the myosin heavy chain, as SMB is generally expressed at higher levels in faster smooth muscle. In this study, we determined the role of this insert on shortening velocity and force regeneration following rapid reduction in muscle length (k(step)) in bladder tissue from a transgenic mouse line expressing the insert at three different levels: wild type (WT, +/+, SMB/SMB), an SMA homozygous type (SMB KO, -/-), and a heterozygous type (+/-, SMB/SMA). Smooth muscle from +/+ bladder shorten faster than both the +/- and -/- bladder smooth muscle when activated with Ca2+, consistent with SMB determining the shortening velocity of smooth muscle. The addition of Pi to the fully activated skinned bladder strips did not affect the rate of shortening for either the +/+ or -/- bladder types but did significantly decrease the rate of shortening for the +/- type. In contrast, the addition of ADP to fully Ca2+ activated bladder strips increased the rate of shortening for all three bladder types. However after thiophosphorylation, ADP slowed the shortening velocity. These data are consistent with shortening velocity being determined by the level of activation (or crossbridge attachment) in smooth muscle. The rates of force regeneration according to the k(step) protocol showed no differences between bladder types and also proved insensitive to either Pi or ADP. These data suggest that the rates of force regeneration were determined not only by the kinetics of the crossbridge cycle, but also by factors outside the contractile apparatus.
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Affiliation(s)
- Peter Karagiannis
- Department of Physiology and Biophysics and Medicine (Cardiology), Case Western Reserve University, Cleveland OH 44106, USA
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Babu GJ, Zheng Z, Natarajan P, Wheeler D, Janssen PM, Periasamy M. Overexpression of sarcolipin decreases myocyte contractility and calcium transient. Cardiovasc Res 2005; 65:177-86. [PMID: 15621045 DOI: 10.1016/j.cardiores.2004.08.012] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2004] [Revised: 08/18/2004] [Accepted: 08/23/2004] [Indexed: 11/26/2022] Open
Abstract
OBJECTIVE Sarcolipin (SLN) is a novel 31-amino-acid protein associated with the sarcoplasmic reticulum (SR) whose function in cardiac muscle is poorly defined. In this study, we tested the hypothesis that SLN is a regulator of SR Ca(2+) transport function by overexpressing SLN in adult rat ventricular myocytes which express low levels of SLN. METHODS Expression of SLN mRNA in rat tissues was analyzed by Northern blot as well by RT-PCR analysis. To define the role of SLN in cardiac muscle contractility, we overexpressed SLN in adult rat ventricular myocytes using adenoviral gene transfer techniques. Localization of SLN in the adult rat ventricular myocytes was determined using confocal microscopy. Myocyte contractility and calcium transients were measured using edge detection and Fura 2AM. RESULTS Our results demonstrate that overexpression of SLN decreased the cell shortening significantly when compared to control myocytes, whereas the time to peak contraction was not altered. In addition, SLN overexpression prolonged the time of 50% relaxation. Calcium transient analysis shows that time to 50% decay of [Ca(2+) ]i was markedly prolonged in SLN-overexpressing myocytes (control -245.0+/-3.78 vs. SLN -199.0+/-3.25 ms, p<0.001). However, there were no significant differences in peak amplitudes of [Ca(2+)](i) between SLN-overexpressing and control myocytes. We further demonstrate that SLN is localized within the SR membrane similar to PLB and SR Ca(2+) ATPase. Co-immunoprecipitation studies indicate that SLN can physically interact with phospholamban. CONCLUSIONS We conclude that SLN may play an important role in regulating the SR calcium ATPase pump, possibly by interacting with phospholamban.
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Affiliation(s)
- Gopal J Babu
- Department of Physiology and Cell Biology, The Ohio State University College of Medicine and Public Health, Columbus, OH 43210, USA
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41
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Babu GJ, Pyne GJ, Zhou Y, Okwuchukuasanya C, Brayden JE, Osol G, Paul RJ, Low RB, Periasamy M. Isoform switching from SM-B to SM-A myosin results in decreased contractility and altered expression of thin filament regulatory proteins. Am J Physiol Cell Physiol 2004; 287:C723-9. [PMID: 15140746 DOI: 10.1152/ajpcell.00029.2004] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We previously generated an isoform-specific gene knockout mouse in which SM-B myosin is permanently replaced by SM-A myosin. In this study, we examined the effects of SM-B myosin loss on the contractile properties of vascular smooth muscle, specifically peripheral mesenteric vessels and aorta. The absence of SM-B myosin leads to decreased velocity of shortening and increased isometric force generation in mesenteric vessels. Surprisingly, the same changes occur in aorta, which contains little or no SM-B myosin in wild-type animals. Calponin and activated mitogen-activated protein kinase expression is increased and caldesmon expression is decreased in aorta, as well as in bladder. Light chain-17b isoform (LC(17b)) expression is increased in aorta. These results suggest that the presence or absence of SM-B myosin is a critical determinant of smooth muscle contraction and that its loss leads to additional changes in thin filament regulatory proteins.
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Affiliation(s)
- Gopal J Babu
- Dept. of Physiology and Cell Biology, Ohio State University College of Medicine, 304 Hamilton Hall, 1645 Neil Avenue, Columbus, OH 43210, USA.
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Babu GJ, Wheeler D, Alzate O, Periasamy M. Solubilization of membrane proteins for two-dimensional gel electrophoresis: identification of sarcoplasmic reticulum membrane proteins. Anal Biochem 2004; 325:121-5. [PMID: 14715292 DOI: 10.1016/j.ab.2003.10.024] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Solubilization of membrane proteins for two-dimensional electrophoresis (2DE) is very difficult. In this study, we report the use of 1,2-diheptanoyl-sn-glycero-3-phosphatdiyl choline (DHPC) as a detergent to solubilize integral membrane proteins for 2DE. Rat ventricular microsomal fractions enriched with sarco(endo)plasmic reticulum (SR) membrane proteins were used as a model system. Compatibility of DHPC with a high concentration of urea increases the solubility of proteins compared with sulphobetaines or ASB-14. Peptide mass analysis assisted in the identification of key SR membrane proteins including SR Ca(2+) ATPase and other membrane proteins, which have not previously been reported on 2DE. These results suggest that DHPC is a better detergent for solubilizing membrane proteins and may be useful in generating proteomic maps for most complex organelles including SR.
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Affiliation(s)
- Gopal J Babu
- Department of Physiology and Cell Biology, The Ohio State University, 304 Hamilton Hall, 1645 Neil Ave, Columbus, OH 43210, USA
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Tuck SA, Maghni K, Poirier A, Babu GJ, Periasamy M, Bates JHT, Leguillette R, Lauzon AM. Time course of airway mechanics of the (+)insert myosin isoform knockout mouse. Am J Respir Cell Mol Biol 2004; 30:326-32. [PMID: 12959948 DOI: 10.1165/rcmb.2003-0254oc] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Two smooth muscle myosin heavy chain isoforms that differ by the presence ([+]insert) or the absence ([-]insert) of a 7-amino acid insert in the motor domain have a 2-fold difference in their in vitro actin filament velocity. We hypothesized that a preferential expression of the fast (+)insert isoform in airway smooth muscle would increase the rate of bronchoconstriction. To verify our hypothesis we measured the time course of bronchoconstriction following a bolus injection of methacholine (160 microg/kg) in (+)insert isoform knockout (KO) and corresponding wild-type (WT) mice. Neither baseline airway resistance (Raw) (0.424 +/- 0.04 for WT and 0.374 +/- 0.01 cm H(2)O.s.ml(-1) for KO) nor peak Raw (4.1 +/- 0.9 for WT and 4.0 +/- 0.5 cm H(2)O.s.ml(-1) for KO) differed between groups. However, the time to peak Raw was significantly longer in the KO (17.2 +/- 0.6 s) compared with the WT (14.6 +/- 0.8 s) mice (P < 0.05). Differentiating Raw with respect to time revealed a greater rate of bronchoconstriction for the WT during the initial 4 s, presumably reflecting the faster shortening velocities under these relatively unloaded conditions. Reverse transcriptase-polymerase chain reaction analysis revealed that the (+)insert myosin isoform mRNA content in the WT airways was 47.8 +/- 5.6%. We conclude that the presence of the (+)insert myosin isoform in the airways increases the rate of bronchoconstriction.
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Affiliation(s)
- Stephanie A Tuck
- Meakins Christie Laboratories, Department of Medicine, McGill University, 3626 St-Urbain St., Montréal, PQ, H2X 2P2 Canada
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Zhou Y, Dirksen WP, Babu GJ, Periasamy M. Differential vasoconstrictions induced by angiotensin II: role of AT1 and AT2 receptors in isolated C57BL/6J mouse blood vessels. Am J Physiol Heart Circ Physiol 2003; 285:H2797-803. [PMID: 12907424 DOI: 10.1152/ajpheart.00466.2003] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Genetically altered mice are increasingly used as experimental models. However, ANG II responses in mouse blood vessels have not been well defined. Therefore, the aim of this study was to determine the role of ANG II in regulating major blood vessels in C57/BL6J mice with isometric force measurements. Our results showed that in mouse abdominal aorta ANG II induced a concentration-dependent contraction (EC50 4.6 nM) with a maximum contraction of 75.1 +/- 4.9% at 100 nM compared with that of 60 mM K+. Similarly, femoral artery also exhibited a contractile response of 76.0 +/- 3.4% to the maximum concentration of ANG II (100 nM). In contrast, ANG II (100 nM)-induced contraction was significantly less in carotid artery (24.5 +/- 6.6%) and only minimal (3.5 +/- 0.31%) in thoracic aorta. The nitric oxide synthase inhibitor N omega-nitro-L-arginine methyl ester and the AT2 antagonist PD-123319 failed to enhance ANG II-induced contractions. However, an AT1 antagonist, losartan (10 microM), completely inhibited ANG II (100 nM) response in abdominal aorta and carotid artery. An AT1 agonist, [Sar1]-ANG II (100 nM), behaved similarly to ANG II (100 nM) in abdominal aorta and carotid artery. RT-PCR analyses showed that mouse thoracic aorta has a significantly lower AT1 mRNA level than abdominal aorta. These results demonstrate that major mouse vessels exhibit differential contractions to ANG II, possibly because of varied AT1 receptor levels.
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MESH Headings
- Angiotensin II/analogs & derivatives
- Angiotensin II/pharmacology
- Animals
- Aorta, Abdominal/physiology
- Aorta, Thoracic/physiology
- Carotid Arteries/physiology
- Enzyme Inhibitors/pharmacology
- Femoral Artery/physiology
- Mice
- Mice, Inbred C57BL
- NG-Nitroarginine Methyl Ester/pharmacology
- RNA, Messenger/analysis
- Rats
- Receptor, Angiotensin, Type 1/genetics
- Receptor, Angiotensin, Type 1/metabolism
- Receptor, Angiotensin, Type 2/metabolism
- Vasoconstriction/drug effects
- Vasoconstriction/physiology
- Vasoconstrictor Agents/pharmacology
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Affiliation(s)
- Yingbi Zhou
- Department of Physiology and Cell Biology, Ohio State Univ. College of Medicine and Public Health, Columbus, OH 43210, USA
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45
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Karagiannis P, Babu GJ, Periasamy M, Brozovich FV. The smooth muscle myosin seven amino acid heavy chain insert's kinetic role in the crossbridge cycle for mouse bladder. J Physiol 2003; 547:463-73. [PMID: 12562924 PMCID: PMC2342653 DOI: 10.1113/jphysiol.2002.035717] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The seven amino acid insert in the smooth muscle myosin heavy chain is thought to regulate the kinetics of contraction, contributing to the differences between fast and slow smooth muscle. The effects of this insert on force and stiffness were determined in bladder tissue of a transgenic mouse line expressing the insert SMB at one of three levels: an SMB wild type (+/+), an SMA homozygous type (-/-) and a heterozygous type (+/-). For skinned muscle, an increase in MgADP or inorganic phosphate (Pi) should shift the distribution of crossbridges in the actomyosin ATPase (AMATPase) to increase the relative population of the crossbridge state prior to ADP release and Pi release, respectively. Exogenous ADP increased force and stiffness in a manner consistent with increasing the Ca2+ concentration in both the +/+ and +/- mouse types. However, the -/- type showed a significantly greater increase in force than in stiffness suggesting that immediately prior to ADP release, the AMATPase either has an additional force producing isomerization state or a slower ADP dissociation rate for the -/- type compared to the +/+ or +/- types. Exogenous Pi led to a significantly greater decrease in stiffness than in force for all three mouse types suggesting that there is a force producing state prior to Pi release. In addition, the increase in Pi showed similar changes in the +/+ and -/- types whereas in the +/- type the decreases in both force and stiffness were greater than the other two mouse types indicating that the insert can affect the cooperativity between myosin heads. In conclusion, the seven amino acid insert modulates the kinetics and/or states of the AMATPase, which could lead to differences in the kinetics of contraction between fast and slow smooth muscle.
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Affiliation(s)
- Peter Karagiannis
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH 44106-4970, USA
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46
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Babu GJ, Loukianov E, Loukianova T, Pyne GJ, Huke S, Osol G, Low RB, Paul RJ, Periasamy M. Loss of SM-B myosin affects muscle shortening velocity and maximal force development. Nat Cell Biol 2001; 3:1025-9. [PMID: 11715025 DOI: 10.1038/ncb1101-1025] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
We used an exon-specific gene-targeting strategy to generate a mouse model deficient only in the SM-B myosin isoform. Here we show that deletion of exon-5B (specific for SM-B) in the gene for the heavy chain of smooth muscle myosin results in a complete loss of SM-B myosin and switching of splicing to the SM-A isoform, without affecting SM1 and SM2 myosin content. Loss of SM-B myosin does not affect survival or cause any overt smooth muscle pathology. Physiological analysis reveals that absence of SM-B myosin results in a significant decrease in maximal force generation and velocity of shortening in smooth muscle tissues. This is the first in vivo study to demonstrate a functional role for the SM-B myosin isoform. We conclude that the extra seven-residue insert in the surface loop 1 of SM-B myosin is a critical determinant of crossbridge cycling and velocity of shortening.
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Affiliation(s)
- G J Babu
- Department of Physiology and Cell Biology, College of Medicine and Public Health, The Ohio State University, 304 Hamilton Hall, 1645 Neil Avenue, Columbus, Ohio 43210, USA
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47
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Lalli MJ, Yong J, Prasad V, Hashimoto K, Plank D, Babu GJ, Kirkpatrick D, Walsh RA, Sussman M, Yatani A, Marbán E, Periasamy M. Sarcoplasmic reticulum Ca(2+) atpase (SERCA) 1a structurally substitutes for SERCA2a in the cardiac sarcoplasmic reticulum and increases cardiac Ca(2+) handling capacity. Circ Res 2001; 89:160-7. [PMID: 11463723 DOI: 10.1161/hh1401.093584] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Ectopic expression of the sarcoplasmic reticulum (SR) Ca(2+) ATPase (SERCA) 1a pump in the mouse heart results in a 2.5-fold increase in total SERCA pump level. SERCA1a hearts show increased rates of contraction/relaxation and enhanced Ca(2+) transients; however, the cellular mechanisms underlying altered Ca(2+) handling in SERCA1a transgenic (TG) hearts are unknown. In this study, using confocal microscopy, we demonstrate that SERCA1a protein traffics to the cardiac SR and structurally substitutes for the endogenous SERCA2a isoform. SR Ca(2+) load measurements revealed that TG myocytes have significantly enhanced SR Ca(2+) load. Confocal line-scan images of field-stimulated SR Ca(2+) release showed an increased rate of Ca(2+) removal in TG myocytes. On the other hand, ryanodine receptor binding activity was decreased by approximately 30%. However, TG myocytes had a greater rate of spontaneous ryanodine receptor opening as measured by spark frequency. Whole-cell L-type Ca(2+) current density was reduced by approximately 50%, whereas the time course of inactivation was unchanged in TG myocytes. These studies provide important evidence that SERCA1a can substitute both structurally and functionally for SERCA2a in the heart and that SERCA1a overexpression can be used to enhance SR Ca(2+) transport and cardiac contractility.
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Affiliation(s)
- M J Lalli
- Division of Cardiology, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
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48
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Rajamanickam C, Sakthivel S, Babu GJ, Lottspeich F, Kadenbach B. Cardiac isoform of alpha-2 macroglobin, a novel serum protein, may induce cardiac hypertrophy in rats. Basic Res Cardiol 2001; 96:23-33. [PMID: 11215529 DOI: 10.1007/s003950170074] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Earlier studies from this laboratory have identified a novel high molecular weight (182 kDa) serum protein suggested to be involved in the development of cardiac hypertrophy. In the present case the role of this novel serum protein in the development of pressure-induced cardiac hypertrophy and the molecular events associated with it in experimental rats has been investigated. Multiple injections of this purified protein intravenously (through tail vein) into the normal animals lead to the development of cardiac hypertrophy and this is accompanied by an induction of muscle specific genes such as that of MLC2 and beta-MHC characteristic of pressure overloaded heart. Further, the hypertrophy-specific serum protein has been found to be identical to rat alpha-2 macroglobulin (alpha-2M) in molecular weight (182 kDa) and in its appearance in blood serum. alpha-2M is an acute phase serum protein that increases markedly after inflammatory stimuli in hepatocytes in liver and gets secreted into the blood. The studies at present suggest that the 182kDa serum protein that appeared during the early stage of development of cardiac hypertrophy in aorta constricted rats is a glycoprotein localized in the heart that showed immunological cross reactivity with alpha-2M and is expressed in the heart as evinced by Northern blot analysis. Further this protein showed certain differences from rat alpha-2M under denaturing conditions in isoelectric focusing and partial peptide mapping. Partial peptide sequencing of the internal peptides of tryptic digest of 182 kDa showed 100% identity of the sequences with alpha-2M sequences. Rat alpha-2M does not, however, have any influence on the development of cardiac hypertrophy and its antibody does not cross react with the 182 kDa protein. These data suggest that the 182 kDa protein that may play an indispensable role in the development of cardiac hypertrophy in experimental rats is cardiac specific, and may be an isoform of liver alpha-2M belonging to macroglobulin family.
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Affiliation(s)
- C Rajamanickam
- Department of Biochemistry, School of Biological Sciences, Centre for Advanced Studies in Functional Genomics, Madurai Kamaraj University, India.
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49
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Ji Y, Lalli MJ, Babu GJ, Xu Y, Kirkpatrick DL, Liu LH, Chiamvimonvat N, Walsh RA, Shull GE, Periasamy M. Disruption of a single copy of the SERCA2 gene results in altered Ca2+ homeostasis and cardiomyocyte function. J Biol Chem 2000; 275:38073-80. [PMID: 10970890 DOI: 10.1074/jbc.m004804200] [Citation(s) in RCA: 98] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
A mouse model carrying a null mutation in one copy of the sarcoplasmic reticulum (SR) Ca(2+)-ATPase isoform 2 (SERCA2) gene, in which SERCA2 protein levels are reduced by approximately 35%, was used to investigate the effects of decreased SERCA2 level on intracellular Ca(2+) homeostasis and contractile properties in isolated cardiomyocytes. When compared with wild-type controls, SR Ca(2+) stores and Ca(2+) release in myocytes of SERCA2 heterozygous mice were decreased by approximately 40-60% and approximately 30-40%, respectively, and the rate of myocyte shortening and relengthening were each decreased by approximately 40%. However, the rate of Ca(2+) transient decline (tau) was not altered significantly, suggesting that compensation was occurring in the removal of Ca(2+) from the cytosol. Phospholamban, which inhibits SERCA2, was decreased by approximately 40% in heterozygous hearts, and basal phosphorylation of Ser-16 and Thr-17, which relieves the inhibition, was increased approximately 2- and 2.1-fold. These results indicate that reduced expression and increased phosphorylation of phospholamban provides compensation for decreased SERCA2 protein levels in heterozygous heart. Furthermore, both expression and current density of the sarcolemmal Na(+)-Ca(2+) exchanger were up-regulated. These results demonstrate that a decrease in SERCA2 levels can directly modify intracellular Ca(2+) homeostasis and myocyte contractility. However, the resulting deficit is partially compensated by alterations in phospholamban/SERCA2 interactions and by up-regulation of the Na(+)-Ca(2+) exchanger.
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Affiliation(s)
- Y Ji
- Division of Cardiology, Department of Internal Medicine, the Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267-0542, USA
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50
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Abstract
Unlike vertebrate skeletal muscle, smooth muscle myosin heavy chain isoforms are encoded by a single gene. Alternative splicing of the primary transcript from a single gene generates four smooth muscle myosin heavy chain isoforms. These isoforms differ both at the carboxyl terminus (SM1 and SM2 isoforms) and at the amino terminus (SM-A and SM-B isoforms). The smooth muscle myosin heavy chain isoforms are differentially expressed during smooth muscle development and in different smooth muscle cell types. The mechanical properties of smooth muscle may be correlated with the myosin heavy chain content/isoform expression. However, the precise function of each smooth muscle myosin heavy chain isoform to muscle contraction remains to be determined. This review mainly focuses on the molecular basis of smooth muscle myosin heavy chain isoform diversity, its expression during development and disease, and its role in muscle physiology.
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Affiliation(s)
- G J Babu
- Laboratory of Molecular Cardiology, Division of Cardiology, Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267, USA
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