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Sun X, Tang X, Qiu H. Cardiac-Specific Suppression of Valosin-Containing Protein Induces Progressive Heart Failure and Premature Mortality Correlating with Temporal Dysregulations in mTOR Complex 2 and Protein Phosphatase 1. Int J Mol Sci 2024; 25:6445. [PMID: 38928151 PMCID: PMC11203954 DOI: 10.3390/ijms25126445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2024] [Revised: 06/06/2024] [Accepted: 06/08/2024] [Indexed: 06/28/2024] Open
Abstract
Valosin-containing protein (VCP), an ATPase-associated protein, is emerging as a crucial regulator in cardiac pathologies. However, the pivotal role of VCP in the heart under physiological conditions remains undetermined. In this study, we tested a hypothesis that sufficient VCP expression is required for cardiac development and physiological cardiac function. Thus, we generated a cardiac-specific VCP knockout (KO) mouse model and assessed the consequences of VCP suppression on the heart through physiological and molecular studies at baseline. Our results reveal that homozygous KO mice are embryonically lethal, whereas heterozygous KO mice with a reduction in VCP by ~40% in the heart are viable at birth but progressively develop heart failure and succumb to mortality at the age of 10 to 12 months. The suppression of VCP induced a selective activation of the mammalian target of rapamycin complex 1 (mTORC1) but not mTORC2 at the early age of 12 weeks. The prolonged suppression of VCP increased the expression (by ~2 folds) and nuclear translocation (by >4 folds) of protein phosphatase 1 (PP1), a key mediator of protein dephosphorylation, accompanied by a remarked reduction (~80%) in AKTSer473 phosphorylation in VCP KO mouse hearts at a later age but not the early stage. These temporal molecular alterations were highly associated with the progressive decline in cardiac function. Overall, our findings shed light on the essential role of VCP in the heart under physiological conditions, providing new insights into molecular mechanisms in the development of heart failure.
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Affiliation(s)
- Xiaonan Sun
- Center for Molecular and Translational Medicine, Institute of Biomedical Science, Georgia State University, Atlanta, GA 30303, USA; (X.S.); (X.T.)
| | - Xicong Tang
- Center for Molecular and Translational Medicine, Institute of Biomedical Science, Georgia State University, Atlanta, GA 30303, USA; (X.S.); (X.T.)
- Cardiovascular Translational Research Center, Department of Internal Medicine, College of Medicine-Phoenix, University of Arizona, Phoenix, AZ 85004, USA
| | - Hongyu Qiu
- Center for Molecular and Translational Medicine, Institute of Biomedical Science, Georgia State University, Atlanta, GA 30303, USA; (X.S.); (X.T.)
- Cardiovascular Translational Research Center, Department of Internal Medicine, College of Medicine-Phoenix, University of Arizona, Phoenix, AZ 85004, USA
- Clinical Translational Sciences (CTS) and Bio5 Institution, University of Arizona, Tucson, AZ 85721, USA
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2
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Chen S, Overberg K, Ghouse Z, Hollmann MW, Weber NC, Coronel R, Zuurbier CJ. Empagliflozin mitigates cardiac hypertrophy through cardiac RSK/NHE-1 inhibition. Biomed Pharmacother 2024; 174:116477. [PMID: 38522235 DOI: 10.1016/j.biopha.2024.116477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 03/16/2024] [Accepted: 03/19/2024] [Indexed: 03/26/2024] Open
Abstract
BACKGROUND SGLT2i reduce cardiac hypertrophy, but underlying mechanisms remain unknown. Here we explore a role for serine/threonine kinases (STK) and sodium hydrogen exchanger 1(NHE1) activities in SGLT2i effects on cardiac hypertrophy. METHODS Isolated hearts from db/db mice were perfused with 1 µM EMPA, and STK phosphorylation sites were examined using unbiased multiplex analysis to detect the most affected STKs by EMPA. Subsequently, hypertrophy was induced in H9c2 cells with 50 µM phenylephrine (PE), and the role of the most affected STK (p90 ribosomal S6 kinase (RSK)) and NHE1 activity in hypertrophy and the protection by EMPA was evaluated. RESULTS In db/db mice hearts, EMPA most markedly reduced STK phosphorylation sites regulated by RSKL1, a member of the RSK family, and by Aurora A and B kinases. GO and KEGG analysis suggested that EMPA inhibits hypertrophy, cell cycle, cell senescence and FOXO pathways, illustrating inhibition of growth pathways. EMPA prevented PE-induced hypertrophy as evaluated by BNP and cell surface area in H9c2 cells. EMPA blocked PE-induced activation of NHE1. The specific NHE1 inhibitor Cariporide also prevented PE-induced hypertrophy without added effect of EMPA. EMPA blocked PE-induced RSK phosphorylation. The RSK inhibitor BIX02565 also suppressed PE-induced hypertrophy without added effect of EMPA. Cariporide mimicked EMPA's effects on PE-treated RSK phosphorylation. BIX02565 decreased PE-induced NHE1 activity, with no further decrease by EMPA. CONCLUSIONS RSK inhibition by EMPA appears as a novel direct cardiac target of SGLT2i. Direct cardiac effects of EMPA exert their anti-hypertrophic effect through NHE-inhibition and subsequent RSK pathway inhibition.
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Affiliation(s)
- Sha Chen
- Department of Anaesthesiology-L.E.I.C.A., Amsterdam University Medical Centers, Location AMC, Cardiovascular Science, Meibergdreef 9, Amsterdam 1105 AZ, the Netherlands
| | - Kenneth Overberg
- Department of Anaesthesiology-L.E.I.C.A., Amsterdam University Medical Centers, Location AMC, Cardiovascular Science, Meibergdreef 9, Amsterdam 1105 AZ, the Netherlands
| | - Zakiya Ghouse
- Department of Anaesthesiology-L.E.I.C.A., Amsterdam University Medical Centers, Location AMC, Cardiovascular Science, Meibergdreef 9, Amsterdam 1105 AZ, the Netherlands
| | - Markus W Hollmann
- Department of Anaesthesiology-L.E.I.C.A., Amsterdam University Medical Centers, Location AMC, Cardiovascular Science, Meibergdreef 9, Amsterdam 1105 AZ, the Netherlands
| | - Nina C Weber
- Department of Anaesthesiology-L.E.I.C.A., Amsterdam University Medical Centers, Location AMC, Cardiovascular Science, Meibergdreef 9, Amsterdam 1105 AZ, the Netherlands
| | - Ruben Coronel
- Department of Experimental Cardiology, Amsterdam UMC, location AMC, Cardiovascular Science, Meibergdreef 9, Amsterdam 1105 AZ, the Netherlands
| | - Coert J Zuurbier
- Department of Anaesthesiology-L.E.I.C.A., Amsterdam University Medical Centers, Location AMC, Cardiovascular Science, Meibergdreef 9, Amsterdam 1105 AZ, the Netherlands.
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Eden M, Leye M, Hahn J, Heilein E, Luzarowski M, Völschow B, Tannert C, Sossalla S, Lucena-Porcel C, Frank D, Frey N. Mst4, a novel cardiac STRIPAK complex-associated kinase, regulates cardiomyocyte growth and survival and is upregulated in human cardiomyopathy. J Biol Chem 2024; 300:107255. [PMID: 38579991 PMCID: PMC11087964 DOI: 10.1016/j.jbc.2024.107255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Revised: 03/15/2024] [Accepted: 03/19/2024] [Indexed: 04/07/2024] Open
Abstract
Myocardial failure is associated with adverse remodeling, including loss of cardiomyocytes, hypertrophy, and alterations in cell-cell contacts. Striatin-interacting phosphatase and kinase (STRIPAK) complexes and their mammalian STE20-like kinase 4 (Mst4) have been linked to development of different diseases. The role and targets of Mst4 in cardiomyocytes have not been investigated yet. Multitissue immunoblot experiments show highly enriched Mst4 expression in rodent hearts. Analyses of human biopsy samples from patients suffering from dilated cardiomyopathy revealed that Mst4 is upregulated (5- to 8-fold p < 0.001) compared with nonfailing controls. Increased abundance of Mst4 could also be detected in mouse models of cardiomyopathy. We confirmed that Mst4 interacts with STRIPAK components in neonatal rat ventricular cardiomyocytes, indicating that STRIPAK is present in the heart. Immunofluorescence stainings and molecular interaction studies revealed that Mst4 is localized to the intercalated disc and interacts with several intercalated disc proteins. Overexpression of Mst4 in cardiomyocytes results in hypertrophy compared with controls. In adult rat cardiomyocytes, Mst4 overexpression increases cellular and sarcomeric fractional shortening (p < 0.05), indicating enhanced contractility. Overexpression of Mst4 also inhibits apoptosis shown by reduction of cleaved caspase3 (-69%, p < 0.0001), caspase7 (-80%, p < 0.0001), and cleaved Parp1 (-27%, p < 0.001). To elucidate potential Mst4 targets, we performed phosphoproteomics analyses in neonatal rat cardiomyocytes after Mst4 overexpression and inhibition. The results revealed target candidates of Mst4 at the intercalated disc. We identified Mst4 as a novel cardiac kinase that is upregulated in cardiomyopathy-regulating cardiomyocyte growth and survival.
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Affiliation(s)
- Matthias Eden
- Department of Internal Medicine III, University of Heidelberg, Heidelberg, Germany; German Centre for Cardiovascular Research, Mannheim/Heidelberg, Germany
| | - Marius Leye
- Department of Internal Medicine III, University of Heidelberg, Heidelberg, Germany; German Centre for Cardiovascular Research, Mannheim/Heidelberg, Germany
| | - Justus Hahn
- Department of Internal Medicine III, University of Heidelberg, Heidelberg, Germany; German Centre for Cardiovascular Research, Mannheim/Heidelberg, Germany
| | - Emanuel Heilein
- Department of Internal Medicine III, University of Heidelberg, Heidelberg, Germany; German Centre for Cardiovascular Research, Mannheim/Heidelberg, Germany
| | - Marcin Luzarowski
- Core Facility for Mass Spectrometry and Proteomics, Center for Molecular Biology at Heidelberg University (ZMBH), Heidelberg, Germany
| | - Bill Völschow
- German Centre for Cardiovascular Research, Kiel, Lübeck, Hamburg, Germany; Department of Cardiology, University Heart and Vascular Center Hamburg, Hamburg, Germany
| | - Christin Tannert
- German Centre for Cardiovascular Research, Kiel, Lübeck, Hamburg, Germany; Department of Internal Medicine III (Cardiology and Angiology), University Hospital Schleswig-Holstein, Kiel, Germany
| | - Samuel Sossalla
- Department of Cardiology, University of Giessen, Giessen and Kerckhoff Heart and Lung Centre, Giessen, Germany
| | - Carlota Lucena-Porcel
- Tissue Bank of the National Center of Tumor Diseases (NCT) Heidelberg, Heidelberg University Hospital, Heidelberg, Germany
| | - Derk Frank
- German Centre for Cardiovascular Research, Kiel, Lübeck, Hamburg, Germany; Department of Internal Medicine III (Cardiology and Angiology), University Hospital Schleswig-Holstein, Kiel, Germany
| | - Norbert Frey
- Department of Internal Medicine III, University of Heidelberg, Heidelberg, Germany; German Centre for Cardiovascular Research, Mannheim/Heidelberg, Germany.
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Park SH, Kim YP, Lee JM, Park DW, Seo JT, Gye MC. Regulation of Phosphorylation of Glycogen Synthase Kinase 3α and the Correlation with Sperm Motility in Human. World J Mens Health 2024; 42:373-383. [PMID: 37635337 PMCID: PMC10949033 DOI: 10.5534/wjmh.230004] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Revised: 03/10/2023] [Accepted: 04/16/2023] [Indexed: 08/29/2023] Open
Abstract
PURPOSE To unravel the mechanism regulating the phosphorylation of glycogen synthase kinase 3 (GSK3) and the correlation between the inhibitory phosphorylation of GSK3α and sperm motility in human. MATERIALS AND METHODS The phosphorylation and priming phosphorylated substrate-specific kinase activity of GSK3 were examined in human spermatozoa with various motility conditions. RESULTS In human spermatozoa, GSK3α/β was localized in the head, midpiece, and principal piece of tail and p-GSK3α(Ser21) was enriched in the midpiece. The ratio of p-GSK3α(Ser21)/GSK3α was positively coupled with normal sperm motility criteria of World Health Organization. In high-motility spermatozoa, p-GSK3α(Ser21) phosphotyrosine (p-Tyr) proteins but p-GSK3α(Tyr279) markedly increased together with decreased kinase activity of GSK3 after incubation in Ca2+ containing medium. In high-motility spermatozoa, p-GSK3α(Ser21) levels were negatively coupled with kinase activity of GSK3, and which was deregulated in low-motility spermatozoa. In high-motility spermatozoa, 6-bromo-indirubin-3'-oxime, an inhibitor of kinase activity of GSK3 increased p-GSK3α(Ser21) and p-Tyr proteins. p-GSK3α(Ser21) and p-Tyr protein levels were decreased by inhibition of PKA and Akt. Calyculin A, a protein phosphatase-1/2A inhibitor, markedly increased the p-GSK3α(Ser21) and p-Tyr proteins, and significantly increased the motility of low-motility human spermatozoa. CONCLUSIONS Down regulation of kinase activity of GSK3α by inhibitory phosphorylation was positively coupled with human sperm motility, and which was regulated by Ca2+, PKA, Akt, and PP1. Small-molecule inhibitors of GSK3 and PP1 can be considered to potentiate human sperm motility.
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Affiliation(s)
- Seung Hyun Park
- Department of Life Science and Institute for Natural Sciences, Hanyang University, Seoul, Korea
| | - Young-Pil Kim
- Department of Life Science and Institute for Natural Sciences, Hanyang University, Seoul, Korea
| | - Jeong Min Lee
- Department of Life Science and Institute for Natural Sciences, Hanyang University, Seoul, Korea
| | - Dong-Wook Park
- Graduate School of Global Pharmaceutical Industry and Clinical Pharmacy, Ajou University, Suwon, Korea
| | - Ju Tae Seo
- JTS Urology Medical Center, Seoul, Korea
| | - Myung Chan Gye
- Department of Life Science and Institute for Natural Sciences, Hanyang University, Seoul, Korea.
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Majdalani P, Levitas A, Krymko H, Slanovic L, Braiman A, Hadad U, Dabsan S, Horev A, Zarivach R, Parvari R. A Missense Variation in PHACTR2 Associates with Impaired Actin Dynamics, Dilated Cardiomyopathy, and Left Ventricular Non-Compaction in Humans. Int J Mol Sci 2023; 24:ijms24021388. [PMID: 36674904 PMCID: PMC9864900 DOI: 10.3390/ijms24021388] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 12/24/2022] [Accepted: 01/06/2023] [Indexed: 01/13/2023] Open
Abstract
Dilated cardiomyopathy (DCM) with left ventricular non-compaction (LVNC) is a primary myocardial disease leading to contractile dysfunction, progressive heart failure, and excessive risk of sudden cardiac death. Using whole-exome sequencing to investigate a possible genetic cause of DCM with LVNC in a consanguineous child, a homozygous nucleotide change c.1532G>A causing p.Arg511His in PHACTR2 was found. The missense change can affect the binding of PHACTR2 to actin by eliminating the hydrogen bonds between them. The amino acid change does not change PHACTR2 localization to the cytoplasm. The patient’s fibroblasts showed a decreased globular to fibrillary actin ratio compared to the control fibroblasts. The re-polymerization of fibrillary actin after treatment with cytochalasin D, which disrupts the actin filaments, was slower in the patient’s fibroblasts. Finally, the patient’s fibroblasts bridged a scar gap slower than the control fibroblasts because of slower and indirect movement. This is the first report of a human variation in this PHACTR family member. The knock-out mouse model presented no significant phenotype. Our data underscore the importance of PHACTR2 in regulating the monomeric actin pool, the kinetics of actin polymerization, and cell movement, emphasizing the importance of actin regulation for the normal function of the human heart.
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Affiliation(s)
- Pierre Majdalani
- The Shraga Segal Department of Microbiology, Immunology & Genetics, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
- The National Institute for Biotechnology in the Negev, Marcus Campus, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
| | - Aviva Levitas
- Department of Pediatric Cardiology, Soroka University Medical Center, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84101, Israel
| | - Hanna Krymko
- Department of Pediatric Cardiology, Soroka University Medical Center, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84101, Israel
| | - Leonel Slanovic
- Department of Pediatric Cardiology, Soroka University Medical Center, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84101, Israel
| | - Alex Braiman
- The Shraga Segal Department of Microbiology, Immunology & Genetics, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
| | - Uzi Hadad
- The Ilse Katz Institute for Nanoscale Science and Technology, Marcus Campus, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
| | - Salam Dabsan
- The Shraga Segal Department of Microbiology, Immunology & Genetics, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
- The National Institute for Biotechnology in the Negev, Marcus Campus, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
| | - Amir Horev
- Pediatric Dermatology Service, Soroka University Medical Center, Beer-Sheva 84101, Israel
| | - Raz Zarivach
- The National Institute for Biotechnology in the Negev, Marcus Campus, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
- Department of Life Sciences, Faculty of Natural Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
| | - Ruti Parvari
- The Shraga Segal Department of Microbiology, Immunology & Genetics, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
- The National Institute for Biotechnology in the Negev, Marcus Campus, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
- Correspondence: ; Tel.: +972-8-647-9967
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6
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Manilall A, Mokotedi L, Gunter S, Le Roux R, Fourie S, Flanagan CA, Millen AME. Increased protein phosphatase 5 expression in inflammation-induced left ventricular dysfunction in rats. BMC Cardiovasc Disord 2022; 22:539. [PMID: 36494772 PMCID: PMC9732989 DOI: 10.1186/s12872-022-02977-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 11/25/2022] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Titin phosphorylation contributes to left ventricular (LV) diastolic dysfunction. The independent effects of inflammation on the molecular pathways that regulate titin phosphorylation are unclear. METHODS We investigated the effects of collagen-induced inflammation and subsequent tumor necrosis factor-α (TNF-α) inhibition on mRNA expression of genes involved in regulating titin phosphorylation in 70 Sprague-Dawley rats. LV diastolic function was assessed with echocardiography. Circulating inflammatory markers were quantified by enzyme-linked immunosorbent assay and relative LV gene expression was assessed by Taqman® polymerase chain reaction. Differences in normally distributed variables between the groups were determined by two-way analysis of variance (ANOVA), followed by Tukey post-hoc tests. For non-normally distributed variables, group differences were determined by Kruskal-Wallis tests. RESULTS Collagen inoculation increased LV relative mRNA expression of vascular cell adhesion molecule 1 (VCAM1), pentraxin 3 (PTX3), and inducible nitric oxide synthase (iNOS) compared to controls, indicating local microvascular inflammation. Collagen inoculation decreased soluble guanylate cyclase alpha-2 (sGCα2) and soluble guanylate cyclase beta-2 (sGCβ2) expression, suggesting downregulation of nitric oxide-soluble guanylate cyclase-cyclic guanosine monophosphate (NO-sGC-cGMP) signaling. Inhibiting TNF-α prevented collagen-induced changes in VCAM1, iNOS, sGCα2 and sGCβ2 expression. Collagen inoculation increased protein phosphatase 5 (PP5) expression. Like LV diastolic dysfunction, increased PP5 expression was not prevented by TNF-α inhibition. CONCLUSION Inflammation-induced LV diastolic dysfunction may be mediated by a TNF-α-independent increase in PP5 expression and dephosphorylation of the N2-Bus stretch element of titin, rather than by TNF-α-induced downregulation of NO-sGC-cGMP pathway-dependent titin phosphorylation. The steady rise in number of patients with inflammation-induced diastolic dysfunction, coupled with low success rates of current therapies warrants a better understanding of the systemic signals and molecular pathways responsible for decreased titin phosphorylation in development of LV diastolic dysfunction. The therapeutic potential of inhibiting PP5 upregulation in LV diastolic dysfunction requires investigation.
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Affiliation(s)
- Ashmeetha Manilall
- grid.11951.3d0000 0004 1937 1135Integrated Molecular Physiology Research Initiative, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown, Johannesburg, 2193 South Africa
| | - Lebogang Mokotedi
- grid.11951.3d0000 0004 1937 1135Integrated Molecular Physiology Research Initiative, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown, Johannesburg, 2193 South Africa
| | - Sulè Gunter
- grid.11951.3d0000 0004 1937 1135Integrated Molecular Physiology Research Initiative, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown, Johannesburg, 2193 South Africa
| | - Regina Le Roux
- grid.11951.3d0000 0004 1937 1135Integrated Molecular Physiology Research Initiative, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown, Johannesburg, 2193 South Africa
| | - Serena Fourie
- grid.11951.3d0000 0004 1937 1135Integrated Molecular Physiology Research Initiative, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown, Johannesburg, 2193 South Africa
| | - Colleen A. Flanagan
- grid.11951.3d0000 0004 1937 1135Integrated Molecular Physiology Research Initiative, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown, Johannesburg, 2193 South Africa
| | - Aletta M. E. Millen
- grid.11951.3d0000 0004 1937 1135Integrated Molecular Physiology Research Initiative, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown, Johannesburg, 2193 South Africa
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Glaser D, Heinick A, Herting JR, Massing F, Müller FU, Pauls P, Rozhdestvensky TS, Schulte JS, Seidl MD, Skryabin BV, Stümpel F, Kirchhefer U. Impaired myocellular Ca 2+ cycling in protein phosphatase PP2A-B56α knockout mice is normalized by β-adrenergic stimulation. J Biol Chem 2022; 298:102362. [PMID: 35963431 PMCID: PMC9478386 DOI: 10.1016/j.jbc.2022.102362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 07/25/2022] [Accepted: 07/26/2022] [Indexed: 11/24/2022] Open
Abstract
The activity of protein phosphatase 2A (PP2A) is determined by the expression and localization of the regulatory B-subunits. PP2A-B56α is the dominant isoform of the B′-family in the heart. Its role in regulating the cardiac response to β-adrenergic stimulation is not yet fully understood. We therefore generated mice deficient in B56α to test the functional cardiac effects in response to catecholamine administration versus corresponding WT mice. We found the decrease in basal PP2A activity in hearts of KO mice was accompanied by a counter-regulatory increase in the expression of B′ subunits (β and γ) and higher phosphorylation of sarcoplasmic reticulum Ca2+ regulatory and myofilament proteins. The higher phosphorylation levels were associated with enhanced intraventricular pressure and relaxation in catheterized KO mice. In contrast, at the cellular level, we detected depressed Ca2+ transient and sarcomere shortening parameters in KO mice at basal conditions. Consistently, the peak amplitude of the L-type Ca2+ current was reduced and the inactivation kinetics of ICaL were prolonged in KO cardiomyocytes. However, we show β-adrenergic stimulation resulted in a comparable peak amplitude of Ca2+ transients and myocellular contraction between KO and WT cardiomyocytes. Therefore, we propose higher isoprenaline-induced Ca2+ spark frequencies might facilitate the normalized Ca2+ signaling in KO cardiomyocytes. In addition, the application of isoprenaline was associated with unchanged L-type Ca2+ current parameters between both groups. Our data suggest an important influence of PP2A-B56α on the regulation of Ca2+ signaling and contractility in response to β-adrenergic stimulation in the myocardium.
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Affiliation(s)
- Dennis Glaser
- Institute of Pharmacology and Toxicology, University of Münster, Münster, Germany
| | - Alexander Heinick
- Institute of Pharmacology and Toxicology, University of Münster, Münster, Germany
| | - Julius R Herting
- Institute of Pharmacology and Toxicology, University of Münster, Münster, Germany
| | - Fabian Massing
- Institute of Pharmacology and Toxicology, University of Münster, Münster, Germany
| | - Frank U Müller
- Institute of Pharmacology and Toxicology, University of Münster, Münster, Germany
| | - Paul Pauls
- Institute of Pharmacology and Toxicology, University of Münster, Münster, Germany
| | - Timofey S Rozhdestvensky
- Department of Medicine, Core Facility Transgenic Animal and Genetic Engineering Models (TRAM), University of Münster, Münster, Germany
| | - Jan S Schulte
- Institute of Pharmacology and Toxicology, University of Münster, Münster, Germany
| | - Matthias D Seidl
- Institute of Pharmacology and Toxicology, University of Münster, Münster, Germany
| | - Boris V Skryabin
- Department of Medicine, Core Facility Transgenic Animal and Genetic Engineering Models (TRAM), University of Münster, Münster, Germany
| | - Frank Stümpel
- Institute of Pharmacology and Toxicology, University of Münster, Münster, Germany
| | - Uwe Kirchhefer
- Institute of Pharmacology and Toxicology, University of Münster, Münster, Germany.
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8
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Sergienko NM, Donner DG, Delbridge LMD, McMullen JR, Weeks KL. Protein phosphatase 2A in the healthy and failing heart: New insights and therapeutic opportunities. Cell Signal 2021; 91:110213. [PMID: 34902541 DOI: 10.1016/j.cellsig.2021.110213] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 12/02/2021] [Accepted: 12/07/2021] [Indexed: 02/06/2023]
Abstract
Protein phosphatases have emerged as critical regulators of phosphoprotein homeostasis in settings of health and disease. Protein phosphatase 2A (PP2A) encompasses a large subfamily of enzymes that remove phosphate groups from serine/threonine residues within phosphoproteins. The heterogeneity in PP2A structure, which arises from the grouping of different catalytic, scaffolding and regulatory subunit isoforms, creates distinct populations of catalytically active enzymes (i.e. holoenzymes) that localise to different parts of the cell. This structural complexity, combined with other regulatory mechanisms, such as interaction of PP2A heterotrimers with accessory proteins and post-translational modification of the catalytic and/or regulatory subunits, enables PP2A holoenzymes to target phosphoprotein substrates in a highly specific manner. In this review, we summarise the roles of PP2A in cardiac physiology and disease. PP2A modulates numerous processes that are vital for heart function including calcium handling, contractility, β-adrenergic signalling, metabolism and transcription. Dysregulation of PP2A has been observed in human cardiac disease settings, including heart failure and atrial fibrillation. Efforts are underway, particularly in the cancer field, to develop therapeutics targeting PP2A activity. The development of small molecule activators of PP2A (SMAPs) and other compounds that selectively target specific PP2A holoenzymes (e.g. PP2A/B56α and PP2A/B56ε) will improve understanding of the function of different PP2A species in the heart, and may lead to the development of therapeutics for normalising aberrant protein phosphorylation in settings of cardiac remodelling and dysfunction.
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Affiliation(s)
- Nicola M Sergienko
- Baker Heart and Diabetes Institute, Melbourne VIC 3004, Australia; Central Clinical School, Monash University, Clayton VIC 3800, Australia
| | - Daniel G Donner
- Baker Heart and Diabetes Institute, Melbourne VIC 3004, Australia; Baker Department of Cardiometabolic Health, The University of Melbourne, Parkville VIC 3010, Australia
| | - Lea M D Delbridge
- Department of Anatomy and Physiology, The University of Melbourne, Parkville VIC 3010, Australia
| | - Julie R McMullen
- Baker Heart and Diabetes Institute, Melbourne VIC 3004, Australia; Baker Department of Cardiometabolic Health, The University of Melbourne, Parkville VIC 3010, Australia; Department of Physiology and Department of Medicine Alfred Hospital, Monash University, Clayton VIC 3800, Australia; Department of Physiology, Anatomy and Microbiology, La Trobe University, Bundoora VIC 3086, Australia; Department of Diabetes, Central Clinical School, Monash University, Clayton VIC 3800, Australia.
| | - Kate L Weeks
- Baker Heart and Diabetes Institute, Melbourne VIC 3004, Australia; Department of Anatomy and Physiology, The University of Melbourne, Parkville VIC 3010, Australia; Baker Department of Cardiometabolic Health, The University of Melbourne, Parkville VIC 3010, Australia; Department of Diabetes, Central Clinical School, Monash University, Clayton VIC 3800, Australia.
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Ai X, Yan J, Pogwizd SM. Serine-threonine protein phosphatase regulation of Cx43 dephosphorylation in arrhythmogenic disorders. Cell Signal 2021; 86:110070. [PMID: 34217833 PMCID: PMC8963383 DOI: 10.1016/j.cellsig.2021.110070] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 06/11/2021] [Accepted: 06/29/2021] [Indexed: 12/11/2022]
Abstract
Regulation of cell-to-cell communication in the heart by the gap junction protein Connexin43 (Cx43) involves modulation of Cx43 phosphorylation state by protein kinases, and dephosphorylation by protein phosphatases. Dephosphorylation of Cx43 has been associated with impaired intercellular coupling and enhanced arrhythmogenesis in various pathologic states. While there has been extensive study of the protein kinases acting on Cx43, there has been limited studies of the protein phosphatases that may underlie Cx43 dephosphorylation. The focus of this review is to introduce serine-threonine protein phosphatase regulation of Cx43 phosphorylation state and cell-to-cell communication, and its impact on arrhythmogenesis in the setting of chronic heart failure and myocardial ischemia, as well as on atrial fibrillation. We also discuss the therapeutic potential of modulating protein phosphatases to treat arrhythmias in these clinical settings.
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Affiliation(s)
- Xun Ai
- Department of Physiology & Biophysics, Rush University, Chicago, IL, United States of America
| | - Jiajie Yan
- Department of Physiology & Biophysics, Rush University, Chicago, IL, United States of America
| | - Steven M Pogwizd
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States of America.
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10
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Dörner MF, Boknik P, Köpp F, Buchwalow IB, Neumann J, Gergs U. Mechanisms of Systolic Cardiac Dysfunction in PP2A, PP5 and PP2AxPP5 Double Transgenic Mice. Int J Mol Sci 2021; 22:ijms22179448. [PMID: 34502355 PMCID: PMC8431312 DOI: 10.3390/ijms22179448] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 08/26/2021] [Accepted: 08/26/2021] [Indexed: 12/15/2022] Open
Abstract
As part of our ongoing studies on the potential pathophysiological role of serine/threonine phosphatases (PP) in the mammalian heart, we have generated transgenic mice with cardiac muscle cell-specific overexpression of PP2Acα (PP2A) and PP5 (PP5). For further studies we crossbred PP2A and PP5 mice to obtain PP2AxPP5 double transgenic mice (PP2AxPP5, DT) and compared them with littermate wild-type mice (WT) serving as a control. The mortality of DT mice was greatly enhanced vs. other genotypes. Cardiac fibrosis was noted histologically and mRNA levels of collagen 1α, collagen 3α and fibronectin 1 were augmented in DT. DT and PP2A mice exhibited an increase in relative heart weight. The ejection fraction (EF) was reduced in PP2A and DT but while the EF of PP2A was nearly normalized after β-adrenergic stimulation by isoproterenol, it was almost unchanged in DT. Moreover, left atrial preparations from DT were less sensitive to isoproterenol treatment both under normoxic conditions and after hypoxia. In addition, levels of the hypertrophy markers atrial natriuretic peptide and B-type natriuretic peptide as well as the inflammation markers interleukin 6 and nuclear factor kappa B were increased in DT. PP2A enzyme activity was enhanced in PP2A vs. WT but similar to DT. This was accompanied by a reduced phosphorylation state of phospholamban at serine-16. Fittingly, the relaxation times in left atria from DT were prolonged. In summary, cardiac co-overexpression of PP2A and PP5 were detrimental to animal survival and cardiac function, and the mechanism may involve dephosphorylation of important regulatory proteins but also fibrosis and inflammation.
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Affiliation(s)
- Mara-Francine Dörner
- Institut für Pharmakologie und Toxikologie, Medizinische Fakultät, Martin-Luther-Universität Halle-Wittenberg, D-06097 Halle, Germany; (M.-F.D.); (F.K.); (J.N.)
- Mibe GmbH Arzneimittel, D-06796 Brehna, Germany
| | - Peter Boknik
- Institut für Pharmakologie und Toxikologie, Medizinische Fakultät, Westfälische Wilhelms-Universität, D-48149 Münster, Germany;
| | - Friedrich Köpp
- Institut für Pharmakologie und Toxikologie, Medizinische Fakultät, Martin-Luther-Universität Halle-Wittenberg, D-06097 Halle, Germany; (M.-F.D.); (F.K.); (J.N.)
| | - Igor B. Buchwalow
- Institute for Hematopathology, Fangdieckstr. 75a, D-22547 Hamburg, Germany;
| | - Joachim Neumann
- Institut für Pharmakologie und Toxikologie, Medizinische Fakultät, Martin-Luther-Universität Halle-Wittenberg, D-06097 Halle, Germany; (M.-F.D.); (F.K.); (J.N.)
| | - Ulrich Gergs
- Institut für Pharmakologie und Toxikologie, Medizinische Fakultät, Martin-Luther-Universität Halle-Wittenberg, D-06097 Halle, Germany; (M.-F.D.); (F.K.); (J.N.)
- Correspondence: ; Tel.: +49-345-557-4093
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11
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Complex functionality of protein phosphatase 1 isoforms in the heart. Cell Signal 2021; 85:110059. [PMID: 34062239 DOI: 10.1016/j.cellsig.2021.110059] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 05/21/2021] [Accepted: 05/28/2021] [Indexed: 02/04/2023]
Abstract
Protein phosphatase 1(PP1) is a key regulator of cardiac function through dephosphorylating serine/threonine residues within target proteins to oppose the function of protein kinases. Studies from failing hearts of animal models and human patients have demonstrated significant increase of PP1 activity in myocardium, while elevated PP1 activity in transgenic mice leads to cardiac dysfunction, suggesting that PP1 might be a therapeutic target to ameliorate cardiac dysfunction in failing hearts. In fact, cardiac overexpression of inhibitor 1, the endogenous inhibitor of PP1, increases cardiac contractility and suppresses heart failure progression. However, this notion of PP1 inhibition for heart failure treatment has been challenged by recent studies on the isoform-specific roles of PP1 in the heart. PP1 is a holoenzyme composed of catalytic subunits (PP1α, PP1β, or PP1γ) and regulatory proteins that target them to distinct subcellular locations for functional specificity. This review will summarize how PP1 regulates phosphorylation of some of the key cardiac proteins involved in Ca2+ handling and cardiac contraction, and the potential role of PP1 isoforms in controlling cardiac physiology and pathophysiology.
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12
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Regulation of Cardiac PKA Signaling by cAMP and Oxidants. Antioxidants (Basel) 2021; 10:antiox10050663. [PMID: 33923287 PMCID: PMC8146537 DOI: 10.3390/antiox10050663] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 04/16/2021] [Accepted: 04/20/2021] [Indexed: 12/31/2022] Open
Abstract
Pathologies, such as cancer, inflammatory and cardiac diseases are commonly associated with long-term increased production and release of reactive oxygen species referred to as oxidative stress. Thereby, protein oxidation conveys protein dysfunction and contributes to disease progression. Importantly, trials to scavenge oxidants by systemic antioxidant therapy failed. This observation supports the notion that oxidants are indispensable physiological signaling molecules that induce oxidative post-translational modifications in target proteins. In cardiac myocytes, the main driver of cardiac contractility is the activation of the β-adrenoceptor-signaling cascade leading to increased cellular cAMP production and activation of its main effector, the cAMP-dependent protein kinase (PKA). PKA-mediated phosphorylation of substrate proteins that are involved in excitation-contraction coupling are responsible for the observed positive inotropic and lusitropic effects. PKA-actions are counteracted by cellular protein phosphatases (PP) that dephosphorylate substrate proteins and thus allow the termination of PKA-signaling. Both, kinase and phosphatase are redox-sensitive and susceptible to oxidation on critical cysteine residues. Thereby, oxidation of the regulatory PKA and PP subunits is considered to regulate subcellular kinase and phosphatase localization, while intradisulfide formation of the catalytic subunits negatively impacts on catalytic activity with direct consequences on substrate (de)phosphorylation and cardiac contractile function. This review article attempts to incorporate the current perception of the functionally relevant regulation of cardiac contractility by classical cAMP-dependent signaling with the contribution of oxidant modification.
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13
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Bers DM, Xiang YK, Zaccolo M. Whole-Cell cAMP and PKA Activity are Epiphenomena, Nanodomain Signaling Matters. Physiology (Bethesda) 2020; 34:240-249. [PMID: 31165682 DOI: 10.1152/physiol.00002.2019] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Novel targeted fluorescent biosensors provide key insights into very local nanodomains of cAMP and PKA activity, and how they respond differently to β-adrenergic activation in cardiac myocytes. This unique spatiotemporal detail in living cells is not available with biochemical measurements of total cellular cAMP and PKA, and provides unique physiological insights.
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Affiliation(s)
- Donald M Bers
- Department of Pharmacology, University of California , Davis, California
| | - Yang K Xiang
- Department of Pharmacology, University of California , Davis, California
| | - Manuela Zaccolo
- Department of Physiology, Anatomy and Genetics, University of Oxford , Oxford , United Kingdom
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14
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Chiang DY, Alsina KM, Corradini E, Fitzpatrick M, Ni L, Lahiri SK, Reynolds JO, Pan X, Scott L, Heck AJR, Wehrens XHT. Rearrangement of the Protein Phosphatase 1 Interactome During Heart Failure Progression. Circulation 2019; 138:1569-1581. [PMID: 29669786 PMCID: PMC6193872 DOI: 10.1161/circulationaha.118.034361] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Heart failure (HF) is a complex disease with a rising prevalence despite advances in treatment. Protein phosphatase 1 (PP1) has long been implicated in HF pathogenesis, but its exact role is both unclear and controversial. Most previous studies measured only the PP1 catalytic subunit (PP1c) without investigating its diverse set of interactors, which confer localization and substrate specificity to the holoenzyme. In this study, we define the PP1 interactome in cardiac tissue and test the hypothesis that this interactome becomes rearranged during HF progression at the level of specific PP1c interactors. METHODS Mice were subjected to transverse aortic constriction and grouped on the basis of ejection fraction into sham, hypertrophy, moderate HF (ejection fraction, 30%-40%), and severe HF (ejection fraction <30%). Cardiac lysates were subjected to affinity purification with anti-PP1c antibodies followed by high-resolution mass spectrometry. PP1 regulatory subunit 7 (Ppp1r7) was knocked down in mouse cardiomyocytes and HeLa cells with adeno-associated virus serotype 9 and siRNA, respectively. Calcium imaging was performed on isolated ventricular myocytes. RESULTS Seventy-one and 98 PP1c interactors were quantified from mouse cardiac and HeLa lysates, respectively, including many novel interactors and protein complexes. This represents the largest reproducible PP1 interactome data set ever captured from any tissue, including both primary and secondary/tertiary interactors. Nine PP1c interactors with changes in their binding to PP1c were strongly associated with HF progression, including 2 known (Ppp1r7 and Ppp1r18) and 7 novel interactors. Within the entire cardiac PP1 interactome, Ppp1r7 had the highest binding to PP1c. Cardiac-specific knockdown in mice led to cardiac dysfunction and disruption of calcium release from the sarcoplasmic reticulum. CONCLUSIONS PP1 is best studied at the level of its interactome, which undergoes significant rearrangement during HF progression. The 9 key interactors that are associated with HF progression may represent potential targets in HF therapy. In particular, Ppp1r7 may play a central role in regulating the PP1 interactome by acting as a competitive molecular "sponge" of PP1c.
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Affiliation(s)
- David Y Chiang
- Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA (D.Y.C.).,Cardiovascular Research Institute (D.Y.C., K.M.A., L.N., S.K.L., L.S., X.H.T.W.), Baylor College of Medicine, Houston, TX.,Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, The Netherlands (D.Y.C., E.C., M.F., A.J.R.H.)
| | - Katherina M Alsina
- Cardiovascular Research Institute (D.Y.C., K.M.A., L.N., S.K.L., L.S., X.H.T.W.), Baylor College of Medicine, Houston, TX.,Integrative Molecular and Biomedical Sciences (K.M.A.), Baylor College of Medicine, Houston, TX
| | - Eleonora Corradini
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, The Netherlands (D.Y.C., E.C., M.F., A.J.R.H.).,Netherlands Proteomics Centre, Utrecht (E.C., M.F., A.J.R.H.)
| | - Martin Fitzpatrick
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, The Netherlands (D.Y.C., E.C., M.F., A.J.R.H.).,Netherlands Proteomics Centre, Utrecht (E.C., M.F., A.J.R.H.)
| | - Li Ni
- Cardiovascular Research Institute (D.Y.C., K.M.A., L.N., S.K.L., L.S., X.H.T.W.), Baylor College of Medicine, Houston, TX.,Department of Molecular Physiology and Biophysics (L.N., S.K.L., J.O.R., X.P., L.S., X.H.T.W.), Baylor College of Medicine, Houston, TX
| | - Satadru K Lahiri
- Cardiovascular Research Institute (D.Y.C., K.M.A., L.N., S.K.L., L.S., X.H.T.W.), Baylor College of Medicine, Houston, TX.,Department of Molecular Physiology and Biophysics (L.N., S.K.L., J.O.R., X.P., L.S., X.H.T.W.), Baylor College of Medicine, Houston, TX
| | - Julia O Reynolds
- Department of Molecular Physiology and Biophysics (L.N., S.K.L., J.O.R., X.P., L.S., X.H.T.W.), Baylor College of Medicine, Houston, TX
| | - Xiaolu Pan
- Department of Molecular Physiology and Biophysics (L.N., S.K.L., J.O.R., X.P., L.S., X.H.T.W.), Baylor College of Medicine, Houston, TX
| | - Larry Scott
- Cardiovascular Research Institute (D.Y.C., K.M.A., L.N., S.K.L., L.S., X.H.T.W.), Baylor College of Medicine, Houston, TX.,Department of Molecular Physiology and Biophysics (L.N., S.K.L., J.O.R., X.P., L.S., X.H.T.W.), Baylor College of Medicine, Houston, TX
| | - Albert J R Heck
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, The Netherlands (D.Y.C., E.C., M.F., A.J.R.H.).,Netherlands Proteomics Centre, Utrecht (E.C., M.F., A.J.R.H.)
| | - Xander H T Wehrens
- Cardiovascular Research Institute (D.Y.C., K.M.A., L.N., S.K.L., L.S., X.H.T.W.), Baylor College of Medicine, Houston, TX.,Department of Molecular Physiology and Biophysics (L.N., S.K.L., J.O.R., X.P., L.S., X.H.T.W.), Baylor College of Medicine, Houston, TX.,Department of Medicine (Cardiology) (X.H.T.W.), and Department of Pediatrics (Cardiology) (X.H.T.W.), Baylor College of Medicine, Houston, TX
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15
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Cao L, Massey IY, Feng H, Yang F. A Review of Cardiovascular Toxicity of Microcystins. Toxins (Basel) 2019; 11:toxins11090507. [PMID: 31480273 PMCID: PMC6783932 DOI: 10.3390/toxins11090507] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 08/27/2019] [Accepted: 08/28/2019] [Indexed: 12/30/2022] Open
Abstract
The mortality rate of cardiovascular diseases (CVD) in China is on the rise. The increasing burden of CVD in China has become a major public health problem. Cyanobacterial blooms have been recently considered a global environmental concern. Microcystins (MCs) are the secondary products of cyanobacteria metabolism and the most harmful cyanotoxin found in water bodies. Recent studies provide strong evidence of positive associations between MC exposure and cardiotoxicity, representing a threat to human cardiovascular health. This review focuses on the effects of MCs on the cardiovascular system and provides some evidence that CVD could be induced by MCs. We summarized the current knowledge of the cardiovascular toxicity of MCs, with regard to direct cardiovascular toxicity and indirect cardiovascular toxicity. Toxicity of MCs is mainly governed by the increasing level of reactive oxygen species (ROS), oxidative stress in mitochondria and endoplasmic reticulum, the inhibition activities of serine/threonine protein phosphatase 1 (PP1) and 2A (PP2A) and the destruction of cytoskeletons, which finally induce the occurrence of CVD. To protect human health from the threat of MCs, this paper also puts forward some directions for further research.
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Affiliation(s)
- Linghui Cao
- Department of Occupational and Environmental Health, Xiangya School of Public Health, Central South University, Changsha 410078, Hunan, China
| | - Isaac Yaw Massey
- Department of Occupational and Environmental Health, Xiangya School of Public Health, Central South University, Changsha 410078, Hunan, China
| | - Hai Feng
- Department of Occupational and Environmental Health, Xiangya School of Public Health, Central South University, Changsha 410078, Hunan, China
| | - Fei Yang
- Department of Occupational and Environmental Health, Xiangya School of Public Health, Central South University, Changsha 410078, Hunan, China.
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16
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Zaitsev AV, Torres NS, Cawley KM, Sabry AD, Warren JS, Warren M. Conduction in the right and left ventricle is differentially regulated by protein kinases and phosphatases: implications for arrhythmogenesis. Am J Physiol Heart Circ Physiol 2019; 316:H1507-H1527. [PMID: 30875259 PMCID: PMC6620685 DOI: 10.1152/ajpheart.00660.2018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Revised: 02/19/2019] [Accepted: 03/07/2019] [Indexed: 12/19/2022]
Abstract
The "stress" kinases cAMP-dependent protein kinase (PKA) and calcium/calmodulin-dependent protein kinase II (CaMKII), phosphorylate the Na+ channel Nav1.5 subunit to regulate its function. However, how the channel regulation translates to ventricular conduction is poorly understood. We hypothesized that the stress kinases positively and differentially regulate conduction in the right (RV) and the left (LV) ventricles. We applied the CaMKII blocker KN93 (2.75 μM), PKA blocker H89 (10 μM), and broad-acting phosphatase blocker calyculin (30 nM) in rabbit hearts paced at a cycle length (CL) of 150-8,000 ms. We used optical mapping to determine the distribution of local conduction delays (inverse of conduction velocity). Control hearts exhibited constant and uniform conduction at all tested CLs. Calyculin (15-min perfusion) accelerated conduction, with greater effect in the RV (by 15.3%) than in the LV (by 4.1%; P < 0.05). In contrast, both KN93 and H89 slowed down conduction in a chamber-, time-, and CL-dependent manner, with the strongest effect in the RV outflow tract (RVOT). Combined KN93 and H89 synergistically promoted conduction slowing in the RV (KN93: 24.7%; H89: 29.9%; and KN93 + H89: 114.2%; P = 0.0016) but not the LV. The progressive depression of RV conduction led to conduction block and reentrant arrhythmias. Protein expression levels of both the CaMKII-δ isoform and the PKA catalytic subunit were higher in the RVOT than in the apical LV (P < 0.05). Thus normal RV conduction requires a proper balance between kinase and phosphatase activity. Dysregulation of this balance due to pharmacological interventions or disease is potentially proarrhythmic. NEW & NOTEWORTHY We show that uniform ventricular conduction requires a precise physiological balance of the activities of calcium/calmodulin-dependent protein kinase II (CaMKII), PKA, and phosphatases, which involves region-specific expression of CaMKII and PKA. Inhibiting CaMKII and/or PKA activity elicits nonuniform conduction depression, with the right ventricle becoming vulnerable to the development of conduction disturbances and ventricular fibrillation/ventricular tachycardia.
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Affiliation(s)
- Alexey V Zaitsev
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah , Salt Lake City, Utah
- Department of Bioengineering, University of Utah , Salt Lake City, Utah
| | - Natalia S Torres
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah , Salt Lake City, Utah
| | - Keiko M Cawley
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah , Salt Lake City, Utah
| | - Amira D Sabry
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah , Salt Lake City, Utah
| | - Junco S Warren
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah , Salt Lake City, Utah
- Department of Internal Medicine, School of Medicine, University of Utah , Salt Lake City, Utah
| | - Mark Warren
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah , Salt Lake City, Utah
- Department of Bioengineering, University of Utah , Salt Lake City, Utah
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17
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Koser F, Loescher C, Linke WA. Posttranslational modifications of titin from cardiac muscle: how, where, and what for? FEBS J 2019; 286:2240-2260. [PMID: 30989819 PMCID: PMC6850032 DOI: 10.1111/febs.14854] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 02/27/2019] [Accepted: 04/13/2019] [Indexed: 12/11/2022]
Abstract
Titin is a giant elastic protein expressed in the contractile units of striated muscle cells, including the sarcomeres of cardiomyocytes. The last decade has seen enormous progress in our understanding of how titin molecular elasticity is modulated in a dynamic manner to help cardiac sarcomeres adjust to the varying hemodynamic demands on the heart. Crucial events mediating the rapid modulation of cardiac titin stiffness are post‐translational modifications (PTMs) of titin. In this review, we first recollect what is known from earlier and recent work on the molecular mechanisms of titin extensibility and force generation. The main goal then is to provide a comprehensive overview of current insight into the relationship between titin PTMs and cardiomyocyte stiffness, notably the effect of oxidation and phosphorylation of titin spring segments on titin stiffness. A synopsis is given of which type of oxidative titin modification can cause which effect on titin stiffness. A large part of the review then covers the mechanically relevant phosphorylation sites in titin, their location along the elastic segment, and the protein kinases and phosphatases known to target these sites. We also include a detailed coverage of the complex changes in phosphorylation at specific titin residues, which have been reported in both animal models of heart disease and in human heart failure, and their correlation with titin‐based stiffness alterations. Knowledge of the relationship between titin PTMs and titin elasticity can be exploited in the search for therapeutic approaches aimed at softening the pathologically stiffened myocardium in heart failure patients.
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18
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Gu SH, Chen CH, Lin PL, Hsieh HY. Role of protein phosphatase 2A in PTTH-stimulated prothoracic glands of the silkworm, Bombyx mori. Gen Comp Endocrinol 2019; 274:97-105. [PMID: 30668972 DOI: 10.1016/j.ygcen.2019.01.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Revised: 01/10/2019] [Accepted: 01/17/2019] [Indexed: 11/16/2022]
Abstract
In the present study, the roles of a major serine/threonine protein phosphatase 2A (PP2A) in prothoracicotropic hormone (PTTH)-stimulated prothoracic glands (PGs) of Bombyx mori were evaluated. Immunoblotting analysis showed that Bombyx PGs contained a structural A subunit (A), a regulatory B subunit (B), and a catalytic C subunit (C), with each subunit undergoing development-specific changes. The protein levels of each subunit were not affected by PTTH treatment. However, the highly conserved tyrosine dephosphorylation of PP2A C subunit (PP2Ac), which appears to be related to activity, was increased by PTTH treatment in a time-dependent manner. We further demonstrated that phospholipase C (PLC), Ca2+, and reactive oxygen species (ROS) are upstream signaling for the PTTH-stimulated dephosphorylation of PP2Ac. The determination of PP2A enzymatic activity showed that PP2A enzymatic activity was stimulated by PTTH treatment both in vitro and in vivo. Okadaic acid (OA), a specific PP2A inhibitor, prevented the PTTH-stimulated dephosphorylation of PP2Ac and reduced both basal and PTTH-stimulated PP2A enzymatic activity. The determination of ecdysteroid secretion showed that treatment with OA did not affect basal ecdysteroid secretion but did significantly inhibit PTTH-stimulated ecdysteroid secretion, indicating that PTTH-stimulated PP2A activity is involved in ecdysteroidogenesis. Treatment with OA stimulated the basal phosphorylation of the extracellular signal-regulated kinase (ERK) and 4E-binding protein (4E-BP) without affecting PTTH-stimulated ERK and 4E-BP phosphorylation. From these results, we hypothesize that PTTH-regulated PP2A signaling is a necessary component for the stimulation of ecdysteroidogenesis, potentially by mediating the link between ERK and TOR signaling pathways.
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Affiliation(s)
- Shi-Hong Gu
- Department of Biology, National Museum of Natural Science, 1 Kuan-Chien Road, Taichung 404, Taiwan, ROC.
| | - Chien-Hung Chen
- Chung Hwa University of Medical Technology, 89 Wen-Hwa 1st Road, Jen-Te Township, Tainan County 717, Taiwan, ROC
| | - Pei-Ling Lin
- Department of Biology, National Museum of Natural Science, 1 Kuan-Chien Road, Taichung 404, Taiwan, ROC
| | - Hsiao-Yen Hsieh
- Department of Biology, National Museum of Natural Science, 1 Kuan-Chien Road, Taichung 404, Taiwan, ROC
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19
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Liu R, Miller C, D’Annibale C, Vo K, Jacobs A. Differential localizations of protein phosphatase 1 isoforms determine their physiological function in the heart. Acta Biochim Biophys Sin (Shanghai) 2019; 51:323-330. [PMID: 30721967 PMCID: PMC6422231 DOI: 10.1093/abbs/gmy171] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 12/10/2018] [Accepted: 12/17/2018] [Indexed: 12/17/2022] Open
Abstract
Protein phosphatase 1 isoforms α, β, and γ (PP1α, PP1β, and PP1γ) are highly homologous in the catalytic domains but have distinct subcellular localizations. In this study, we utilized both primary cell culture and knockout mice to investigate the isoform-specific roles of PP1s in the heart. In both neonatal and adult cardiac myocytes, PP1β was mainly localized in the nucleus, compared to the predominant presence of PP1α and PP1γ in the cytoplasm. Adenovirus-mediated overexpression of PP1α led to decreased phosphorylation of phospholamban, which was not influenced by overexpression of either PP1β or PP1γ. Interestingly, only cardiac-specific knockout of PP1β resulted in increased HDAC7 phosphorylation, consistent with the predominant nuclear localization of PP1β. Functionally, deletion of either PP1 isoform resulted in reduced fractional shortening in aging mice, however only PP1β deletion resulted in interstitial fibrosis in mice as early as 3 weeks of age. Deletion of neither PP1 isoform had any effect on pathological cardiac hypertrophy induced by 2 weeks of pressure overload stimulation. Together, our data suggest that PP1 isoforms have differential localizations to regulate the phosphorylation of their specific substrates for the physiological function in the heart.
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Affiliation(s)
- Ruijie Liu
- Department of Biomedical Sciences, Grand Valley State University, Allendale, MI, USA
| | - Christian Miller
- Department of Biomedical Sciences, Grand Valley State University, Allendale, MI, USA
| | - Christiana D’Annibale
- Department of Biomedical Sciences, Grand Valley State University, Allendale, MI, USA
| | - Kimberly Vo
- Department of Biomedical Sciences, Grand Valley State University, Allendale, MI, USA
| | - Ashley Jacobs
- Department of Biomedical Sciences, Grand Valley State University, Allendale, MI, USA
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Age-Dependent Protein Expression of Serine/Threonine Phosphatases and Their Inhibitors in the Human Cardiac Atrium. Adv Med 2019; 2019:2675972. [PMID: 30719459 PMCID: PMC6334353 DOI: 10.1155/2019/2675972] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Revised: 11/22/2018] [Accepted: 11/29/2018] [Indexed: 12/20/2022] Open
Abstract
Heart failure and aging of the heart show many similarities regarding hemodynamic and biochemical parameters. There is evidence that heart failure in experimental animals and humans is accompanied and possibly exacerbated by increased activity of protein phosphatase (PP) 1 and/or 2A. Here, we wanted to study the age-dependent protein expression of major members of the protein phosphatase family in human hearts. Right atrial samples were obtained during bypass surgery. Patients (n=60) were suffering from chronic coronary artery disease (CCS 2-3; New York Heart Association (NYHA) stage 1-3). Age ranged from 48 to 84 years (median 69). All patients included in the study were given β-adrenoceptor blockers. Other medications included angiotensin-converting enzyme (ACE) or angiotensin-receptor-1 (AT1) inhibitors, statins, nitrates, and acetylsalicylic acid (ASS). 100 µg of right atrial homogenates was used for western blotting. Antibodies against catalytic subunits (and their major regulatory proteins) of all presently known cardiac serine/threonine phosphatases were used for antigen detection. In detail, we studied the expression of the catalytic subunit of PP1 (PP1c); I1 PP1 and I2 PP1, proteins that can inhibit the activity of PP1c; the catalytic subunit of PP2A (PP2Ac); regulatory A-subunit of PP2A (PP2AA); regulatory B56α-subunit of PP2A (PP2AB); I1 PP2A and I2 PP2A, inhibitory subunits of PP2A; catalytic and regulatory subunits of calcineurin: PP2BA and PP2BB; PP2C; PP5; and PP6. All data were obtained within the linear range of the assay. There was a significant decline in PP2Ac and I2 PP2A expression in older patients, whereas all other parameters remained unchanged with age. It remains to be elucidated whether the decrease in the protein expression of I2 PP2A might elevate cardiac PP2A activity in a detrimental way or is overcome by a reduced protein expression and thus a reduced activity of PP2Ac.
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The reduced activity of PP-1α under redox stress condition is a consequence of GSH-mediated transient disulfide formation. Sci Rep 2018; 8:17711. [PMID: 30531830 PMCID: PMC6286341 DOI: 10.1038/s41598-018-36267-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Accepted: 11/09/2018] [Indexed: 12/19/2022] Open
Abstract
Heart failure is the most common cause of morbidity and hospitalization in the western civilization. Protein phosphatases play a key role in the basal cardiac contractility and in the responses to β-adrenergic stimulation with type-1 phosphatase (PP-1) being major contributor. We propose here that formation of transient disulfide bridges in PP-1α might play a leading role in oxidative stress response. First, we established an optimized workflow, the so-called "cross-over-read" search method, for the identification of disulfide-linked species using permutated databases. By applying this method, we demonstrate the formation of unexpected transient disulfides in PP-1α to shelter against over-oxidation. This protection mechanism strongly depends on the fast response in the presence of reduced glutathione. Our work points out that the dimerization of PP-1α involving Cys39 and Cys127 is presumably important for the protection of PP-1α active surface in the absence of a substrate. We finally give insight into the electron transport from the PP-1α catalytic core to the surface. Our data suggest that the formation of transient disulfides might be a general mechanism of proteins to escape from irreversible cysteine oxidation and to prevent their complete inactivation.
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Sequeira V, Maack C. Rebalancing protein phosphorylation in heart failure to prevent arrhythmias. Eur J Heart Fail 2018; 20:1686-1689. [PMID: 30328664 DOI: 10.1002/ejhf.1315] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Accepted: 08/10/2018] [Indexed: 12/28/2022] Open
Affiliation(s)
- Vasco Sequeira
- Comprehensive Heart Failure Center (CHFC), University Clinic Würzburg, Würzburg, Germany
| | - Christoph Maack
- Comprehensive Heart Failure Center (CHFC), University Clinic Würzburg, Würzburg, Germany
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Baskaran R, Velmurugan BK. Protein phosphatase 2A as therapeutic targets in various disease models. Life Sci 2018; 210:40-46. [PMID: 30170071 DOI: 10.1016/j.lfs.2018.08.063] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Revised: 07/25/2018] [Accepted: 08/27/2018] [Indexed: 12/24/2022]
Abstract
There are a large number of signalling pathways responsible for transmitting information within the cell. Although cellular signalling is thought to be majorly governed by protein kinases 'cascade effects'; their antagonists protein phosphatases also play a crucial dual role in signal transduction. By dephosphorylating the proteins involved in signalling pathways, phosphatases may lead to their activation and sometimes they may terminate a signal generated by kinases activity. Due to counterbalancing the function of phosphorylation, the protein phosphatases are very important to signal transduction processes and thus the control of phosphatase activity is as significant as kinases, in the regulation of a plethora of cellular processes. In general, the protein phosphatases are comprised of a catalytic subunit with one or more regulatory and/or targeting subunits associated with it. The Protein Phosphatase 2A (PP2A), a member of serine/threonine phosphatases family, is ubiquitously expressed a remarkably conserved enzyme in the cell. Its catalytic activity has been highly regulated and may have enormous therapeutic potential which is still untapped. It has specificities for a number of substrates which witnessed its involvement in various signalling modules of cell cycle regulation, cell morphology and development. Thus it can be an appropriate target for studying different diseases associated with abnormal signal transduction pathways such as neurodegenerative diseases and malignancies. This review will focus on the structure and regulatory pathways of PP2A. The de-regulation of PP2A in some specific pathology such as Cancer, Heart diseases, Neurodegenerative disorders and Diabetes will also be touched upon.
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Affiliation(s)
- Rathinasamy Baskaran
- National Institute of Cancer Research, National Health Research Institutes, Zhunan, Miaoli County, Taiwan
| | - Bharath Kumar Velmurugan
- Toxicology and Biomedicine Research Group, Faculty of Applied Sciences, Ton Duc Thang University, Ho Chi Minh City, Vietnam.
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Cuello F, Wittig I, Lorenz K, Eaton P. Oxidation of cardiac myofilament proteins: Priming for dysfunction? Mol Aspects Med 2018; 63:47-58. [PMID: 30130564 DOI: 10.1016/j.mam.2018.08.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Revised: 08/13/2018] [Accepted: 08/17/2018] [Indexed: 02/07/2023]
Abstract
Oxidants are produced endogenously and can react with and thereby post-translationally modify target proteins. They have been implicated in the redox regulation of signal transduction pathways conferring protection, but also in mediating oxidative stress and causing damage. The difference is that in scenarios of injury the amount of oxidants generated is higher and/or the duration of oxidant exposure sustained. In the cardiovascular system, oxidants are important for blood pressure homeostasis, for unperturbed cardiac function and also contribute to the observed protection during ischemic preconditioning. In contrast, oxidative stress accompanies all major cardiovascular pathologies and has been attributed to mediate contractile dysfunction in part by inducing oxidative modifications in myofilament proteins. However, the proportion to which oxidative modifications of contractile proteins are beneficial or causatively mediate disease progression needs to be carefully reconsidered. These antithetical aspects will be discussed in this review with special focus on direct oxidative post-translational modifications of myofilament proteins that have been described to occur in vivo and to regulate actin-myosin interactions in the cardiac myocyte sarcomere, the methodologies for detection of oxidative post-translational modifications in target proteins and the feasibility of antioxidant therapy strategies as a potential treatment for cardiac disorders.
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Affiliation(s)
- Friederike Cuello
- Institute of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; DZHK (German Center for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, Germany.
| | - Ilka Wittig
- Functional Proteomics, SFB 815 Core Unit, Faculty of Medicine, Johann Wolfgang Goethe University, Frankfurt am Main, Germany; DZHK (German Center for Cardiovascular Research), Partner Site Rhine-Main, Germany
| | - Kristina Lorenz
- Comprehensive Heart Failure Center, Würzburg, Leibniz-Institut für Analytische Wissenschaften-ISAS-e.V. Dortmund, West German Heart and Vascular Center, Essen, Germany
| | - Philip Eaton
- King's British Heart Foundation Centre, King's College London, UK
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Qadota H, Matsunaga Y, Bagchi P, Lange KI, Carrier KJ, Pols WV, Swartzbaugh E, Wilson KJ, Srayko M, Pallas DC, Benian GM. Protein phosphatase 2A is crucial for sarcomere organization in Caenorhabditis elegans striated muscle. Mol Biol Cell 2018; 29:2084-2097. [PMID: 29949401 PMCID: PMC6232960 DOI: 10.1091/mbc.e18-03-0192] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 06/12/2018] [Accepted: 06/18/2018] [Indexed: 01/06/2023] Open
Abstract
Protein phosphatase 2A (PP2A) is a heterotrimer composed of single catalytic and scaffolding subunits and one of several possible regulatory subunits. We identified PPTR-2, a regulatory subunit of PP2A, as a binding partner for the giant muscle protein UNC-89 (obscurin) in Caenorhabditis elegans. PPTR-2 is required for sarcomere organization when its paralogue, PPTR-1, is deficient. PPTR-2 localizes to the sarcomere at dense bodies and M-lines, colocalizing with UNC-89 at M-lines. PP2A components in C. elegans include one catalytic subunit LET-92, one scaffolding subunit (PAA-1), and five regulatory subunits (SUR-6, PPTR-1, PPTR-2, RSA-1, and CASH-1). In adult muscle, loss of function in any of these subunits results in sarcomere disorganization. rsa-1 mutants show an interesting phenotype: one of the two myosin heavy chains, MHC A, localizes as closely spaced double lines rather than single lines. This "double line" phenotype is found in rare missense mutants of the head domain of MHC B myosin, such as unc-54(s74). Analysis of phosphoproteins in the unc-54(s74) mutant revealed two additional phosphoserines in the nonhelical tailpiece of MHC A. Antibodies localize PPTR-1, PAA-1, and SUR-6 to I-bands and RSA-1 to M-lines and I-bands. Therefore, PP2A localizes to sarcomeres and functions in the assembly or maintenance of sarcomeres.
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Affiliation(s)
- Hiroshi Qadota
- Department of Pathology, Emory University, Atlanta, GA 30322
| | - Yohei Matsunaga
- Department of Pathology, Emory University, Atlanta, GA 30322
| | - Pritha Bagchi
- Emory Integrated Proteomics Core, Emory University, Atlanta, GA 30322
| | - Karen I. Lange
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
| | - Karma J. Carrier
- Department of Biochemistry and Winship Cancer Institute, Emory University, Atlanta, GA 30322
| | | | | | | | - Martin Srayko
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
| | - David C. Pallas
- Department of Biochemistry and Winship Cancer Institute, Emory University, Atlanta, GA 30322
| | - Guy M. Benian
- Department of Pathology, Emory University, Atlanta, GA 30322
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Rizvi F, Siddiqui R, DeFranco A, Homar P, Emelyanova L, Holmuhamedov E, Ross G, Tajik AJ, Jahangir A. Simvastatin reduces TGF-β1-induced SMAD2/3-dependent human ventricular fibroblasts differentiation: Role of protein phosphatase activation. Int J Cardiol 2018; 270:228-236. [PMID: 30220377 DOI: 10.1016/j.ijcard.2018.06.061] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 06/18/2018] [Indexed: 02/07/2023]
Abstract
BACKGROUND Excessive cardiac fibrosis due to maladaptive remodeling leads to progression of cardiac dysfunction and is modulated by TGF-β1-activated intracellular phospho-SMAD signaling effectors and transcription regulators. SMAD2/3 phosphorylation, regulated by protein-phosphatases, has been studied in different cell types, but its role in human ventricular fibroblasts (hVFs) is not defined as a target to reduce cytokine-mediated excessive fibrotic response and adverse cardiac remodeling. Statins are a class of drugs reported to reduce cardiac fibrosis, although underlying mechanisms are not completely understood. We aimed to assess whether simvastatin-mediated reduction in TGF-β1-augmented profibrotic response involves reduction in phospho-SMAD2/3 owing to activation of protein-phosphatase in hVFs. METHODS AND RESULTS Cultures of hVFs were used. Effect of simvastatin on TGF-β1-treated hVF proliferation, cytotoxicity, myofibroblast differentiation/activation, profibrotic gene expression and protein-phosphatase activity was assessed. Simvastatin (1 μM) reduced effect of TGF-β1 (5 ng/mL) on hVF proliferation, myofibroblast differentiation (reduced α-smooth muscle actin [α-SMA-expression]) and activation (decreased procollagen-peptide release). Simvastatin also reduced TGF-β1-stimulated time-dependent increases in SMAD2/3 phosphorylation and nuclear translocation, mediated through catalytic activation of protein-phosphatases PPM1A and PP2A, which physically interact with SMAD2/3, thereby promoting their dephosphorylation. Effect of simvastatin on TGF-β1-induced fibroblast activation was annulled by okadaic acid, an inhibitor of protein-phosphatase. CONCLUSIONS This proof-of-concept study using an in vitro experimental cell culture model identifies the protective role of simvastatin against TGF-β1-induced hVF transformation into activated myofibroblasts through activation of protein phosphatase, a novel target that can be therapeutically modulated to curb excessive cardiac fibrosis associated with maladaptive cardiac remodeling.
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Affiliation(s)
- Farhan Rizvi
- Center for Integrative Research on Cardiovascular Aging (CIRCA), Aurora Research Institute, Aurora Health Care, 2801 W. Kinnickinnic River Parkway, Milwaukee, WI, USA.
| | - Ramail Siddiqui
- Center for Integrative Research on Cardiovascular Aging (CIRCA), Aurora Research Institute, Aurora Health Care, 2801 W. Kinnickinnic River Parkway, Milwaukee, WI, USA
| | - Alessandra DeFranco
- Center for Integrative Research on Cardiovascular Aging (CIRCA), Aurora Research Institute, Aurora Health Care, 2801 W. Kinnickinnic River Parkway, Milwaukee, WI, USA
| | - Peter Homar
- Center for Integrative Research on Cardiovascular Aging (CIRCA), Aurora Research Institute, Aurora Health Care, 2801 W. Kinnickinnic River Parkway, Milwaukee, WI, USA
| | - Larisa Emelyanova
- Center for Integrative Research on Cardiovascular Aging (CIRCA), Aurora Research Institute, Aurora Health Care, 2801 W. Kinnickinnic River Parkway, Milwaukee, WI, USA
| | - Ekhson Holmuhamedov
- Center for Integrative Research on Cardiovascular Aging (CIRCA), Aurora Research Institute, Aurora Health Care, 2801 W. Kinnickinnic River Parkway, Milwaukee, WI, USA
| | - Gracious Ross
- Center for Integrative Research on Cardiovascular Aging (CIRCA), Aurora Research Institute, Aurora Health Care, 2801 W. Kinnickinnic River Parkway, Milwaukee, WI, USA
| | - A Jamil Tajik
- Center for Integrative Research on Cardiovascular Aging (CIRCA), Aurora Research Institute, Aurora Health Care, 2801 W. Kinnickinnic River Parkway, Milwaukee, WI, USA; Aurora Cardiovascular Services, Aurora Sinai/Aurora St. Luke's Medical Centers, University of Wisconsin School of Medicine and Public Health, 2801 W. Kinnickinnic River Parkway, Milwaukee, WI, USA
| | - Arshad Jahangir
- Center for Integrative Research on Cardiovascular Aging (CIRCA), Aurora Research Institute, Aurora Health Care, 2801 W. Kinnickinnic River Parkway, Milwaukee, WI, USA; Aurora Cardiovascular Services, Aurora Sinai/Aurora St. Luke's Medical Centers, University of Wisconsin School of Medicine and Public Health, 2801 W. Kinnickinnic River Parkway, Milwaukee, WI, USA
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Protein phosphatase 5 regulates titin phosphorylation and function at a sarcomere-associated mechanosensor complex in cardiomyocytes. Nat Commun 2018; 9:262. [PMID: 29343782 PMCID: PMC5772059 DOI: 10.1038/s41467-017-02483-3] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Accepted: 12/04/2017] [Indexed: 12/14/2022] Open
Abstract
Serine/threonine protein phosphatase 5 (PP5) is ubiquitously expressed in eukaryotic cells; however, its function in cardiomyocytes is unknown. Under basal conditions, PP5 is autoinhibited, but enzymatic activity rises upon binding of specific factors, such as the chaperone Hsp90. Here we show that PP5 binds and dephosphorylates the elastic N2B-unique sequence (N2Bus) of titin in cardiomyocytes. Using various binding and phosphorylation tests, cell-culture manipulation, and transgenic mouse hearts, we demonstrate that PP5 associates with N2Bus in vitro and in sarcomeres and is antagonistic to several protein kinases, which phosphorylate N2Bus and lower titin-based passive tension. PP5 is pathologically elevated and likely contributes to hypo-phosphorylation of N2Bus in failing human hearts. Furthermore, Hsp90-activated PP5 interacts with components of a sarcomeric, N2Bus-associated, mechanosensor complex, and blocks mitogen-activated protein-kinase signaling in this complex. Our work establishes PP5 as a compartmentalized, well-controlled phosphatase in cardiomyocytes, which regulates titin properties and kinase signaling at the myofilaments. Protein phosphatase 5 (PP5) is expressed in many cell types but its role in cardiomyocytes is unknown. Here the authors show that PP5 binds and dephosphorylates elastic titin in cardiac sarcomeres, and that PP5 is increased in heart failure, reducing cardiomyocyte compliance.
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28
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Rajtik T, Goncalvesova E, Varga ZV, Leszek P, Kusmierczyk M, Hulman M, Kyselovic J, Ferdinandy P, Adameova A. Posttranslational modifications of calcium/calmodulin-dependent protein kinase IIδ and its downstream signaling in human failing hearts. Am J Transl Res 2017; 9:3573-3585. [PMID: 28861149 PMCID: PMC5575172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Accepted: 07/16/2017] [Indexed: 06/07/2023]
Abstract
BACKGROUND In human failing hearts (HF) of different origin (coronary artery disease-CAD, dilated-DCM, restrictive and hypertrophic cardiomyopathy-OTHER), we investigated the active forms of Ca2+/calmodulin-dependent protein kinase IIδ (p-Thr287-CaMKIIδ, oxMet281/282-CaMKIIδ) and their role in phenotypes of the disease. METHODS AND RESULTS Although basic diagnostic and clinical markers indicating the attenuated cardiac contractility and remodeling were comparable in HF groups, CaMKIIδ-mediated axis was different. P-Thr287-CaMKIIδ was unaltered in CAD group, whereas it was upregulated in non-ischemic cardiomyopathic groups. No correlation between the upregulated p-Thr287-CaMKIIδ and QT interval prolongation was detected. Unlike in DCM, oxMet281/282-CaMKIIδ did not differ among HF groups. Independently of CaMKIIδ phosphorylation/oxidation, activation of its downstreams-phospholamban and cardiac myosin binding protein-C was significantly downregulated supporting both diminished cardiac lusitropy and inotropy in all hearts. Content of sarcoplasmic reticulum Ca2+-ATPase 2a in all HF was unchanged. Protein phosphatase1β was upregulated in CAD and DCM only, while 2A did not differ among groups. CONCLUSION This is the first demonstration that the posttranslational activation of CaMKIIδ differs in HF depending on etiology. Lower levels of downstream molecular targets of CaMKIIδ do not correlate with either activation of CaMKIIδ or the expression of major protein phosphatases in the HF. Thus, it is unlikely that these mechanisms exclusively underlie failing of the heart.
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Affiliation(s)
- Tomas Rajtik
- Department of Pharmacology & Toxicology, Faculty of Pharmacy, Comenius UniversityBratislava, Slovak Republic
| | - Eva Goncalvesova
- Department of Heart Failure & Transplantation, The National Institute of Cardiovascular DiseasesBratislava, Slovak Republic
| | - Zoltan V Varga
- Department of Pharmacology & Pharmacotherapy, Semmelweis UniversityBudapest, Hungary
| | | | | | - Michal Hulman
- Clinic of Heart Surgery, The National Institute of Cardiovascular DiseasesBratislava, Slovak Republic
| | - Jan Kyselovic
- Department of Pharmacology & Toxicology, Faculty of Pharmacy, Comenius UniversityBratislava, Slovak Republic
| | - Peter Ferdinandy
- Department of Pharmacology & Pharmacotherapy, Semmelweis UniversityBudapest, Hungary
| | - Adriana Adameova
- Department of Pharmacology & Toxicology, Faculty of Pharmacy, Comenius UniversityBratislava, Slovak Republic
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Wang Y, Wang S, Lei M, Boyett M, Tsui H, Liu W, Wang X. The p21-activated kinase 1 (Pak1) signalling pathway in cardiac disease: from mechanistic study to therapeutic exploration. Br J Pharmacol 2017; 175:1362-1374. [PMID: 28574147 DOI: 10.1111/bph.13872] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 05/12/2017] [Accepted: 05/17/2017] [Indexed: 01/01/2023] Open
Abstract
p21-activated kinase 1 (Pak1) is a member of the highly conserved family of serine/threonine protein kinases regulated by Ras-related small G-proteins, Cdc42/Rac1. It has been previously demonstrated to be involved in cardiac protection. Based on recent studies, this review provides an overview of the role of Pak1 in cardiac diseases including disrupted Ca2+ homoeostasis-related cardiac arrhythmias, adrenergic stress- and pressure overload-induced hypertrophy, and ischaemia/reperfusion injury. These findings demonstrate the important role of Pak1 mediated through the phosphorylation and transcriptional modification of hypertrophy and/or arrhythmia-related genes. This review also discusses the anti-arrhythmic and anti-hypertrophic, protective function of Pak1 and the beneficial effects of fingolimod (an FDA-approved sphingolipid drug), a Pak1 activator, and its ability to prevent arrhythmias and cardiac hypertrophy. These findings also highlight the therapeutic potential of Pak1 signalling in the treatment and prevention of cardiac diseases. LINKED ARTICLES This article is part of a themed section on Spotlight on Small Molecules in Cardiovascular Diseases. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.8/issuetoc.
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Affiliation(s)
- Yanwen Wang
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
| | - Shunyao Wang
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
| | - Ming Lei
- Department of Pharmacology, The University of Oxford, Oxford, UK
| | - Mark Boyett
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
| | - Hoyee Tsui
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
| | - Wei Liu
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
| | - Xin Wang
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
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Differential regulation of protein phosphatase 1 (PP1) isoforms in human heart failure and atrial fibrillation. Basic Res Cardiol 2017; 112:43. [PMID: 28597249 DOI: 10.1007/s00395-017-0635-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2017] [Accepted: 06/06/2017] [Indexed: 10/19/2022]
Abstract
Protein phosphatase 1 (PP1) is a key regulator of important cardiac signaling pathways. Dysregulation of PP1 has been heavily implicated in cardiac dysfunctions. Accordingly, pharmacological targeting of PP1 activity is considered for therapeutic intervention in human cardiomyopathies. Recent evidence from animal models implicated previously unrecognized, isoform-specific activities of PP1 in the healthy and diseased heart. Therefore, this study examined the expression of the distinct PP1 isoforms PP1α, β, and γ in human heart failure (HF) and atrial fibrillation (AF) and addressed the consequences of β-adrenoceptor blocker (beta-blocker) therapy for HF patients with reduced ejection fraction on PP1 isoform expression. Using western blot analysis, we found greater abundance of PP1 isoforms α and γ but unaltered PP1β levels in left ventricular myocardial tissues from HF patients as compared to non-failing controls. However, expression of all three PP1 isoforms was higher in atrial appendages from patients with AF compared to patients with sinus rhythm. Moreover, we found that in human failing ventricles, beta-blocker therapy was associated with lower PP1α abundance and activity, as indicated by higher phosphorylation of the PP1α-specific substrate eIF2α. Greater eIF2α phosphorylation is a known repressor of protein translation, and accordingly, we found lower levels of the endoplasmic reticulum (ER) stress marker Grp78 in the very same samples. We propose that isoform-specific targeting of PP1α activity may be a novel and innovative therapeutic strategy for the treatment of human cardiac diseases by reducing ER stress conditions.
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31
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Hood AR, Ai X, Pogwizd SM. Regulation of cardiac gap junctions by protein phosphatases. J Mol Cell Cardiol 2017; 107:52-57. [PMID: 28478048 DOI: 10.1016/j.yjmcc.2017.05.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Revised: 04/13/2017] [Accepted: 05/02/2017] [Indexed: 01/16/2023]
Abstract
Sufficient connexin-mediated intercellular coupling is critical to maintain gap junctional communication for proper cardiac function. Alterations in connexin phosphorylation state, particularly dephosphorylation of connexin 43 (Cx43), may impact cell coupling and conduction in disease states. Cx43 dephosphorylation may be carried out by protein phosphatase activity. Here, we present an overview of the key phosphatases known to interact with Cx43 or modulators of Cx43, as well as some possible therapeutic targets to regulate phosphatase activity in the heart.
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Affiliation(s)
- Ashleigh R Hood
- Department of Biomedical Engineering, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Xun Ai
- Department of Biophysics and Physiology, Rush University, Chicago, IL, United States
| | - Steven M Pogwizd
- Department of Biomedical Engineering, University of Alabama at Birmingham, Birmingham, AL, United States; Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States.
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32
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Aromolaran AS, Chahine M, Boutjdir M. Regulation of Cardiac Voltage-Gated Sodium Channel by Kinases: Roles of Protein Kinases A and C. Handb Exp Pharmacol 2017; 246:161-184. [PMID: 29032483 DOI: 10.1007/164_2017_53] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
In the heart, voltage-gated sodium (Nav) channel (Nav1.5) is defined by its pore-forming α-subunit and its auxiliary β-subunits, both of which are important for its critical contribution to the initiation and maintenance of the cardiac action potential (AP) that underlie normal heart rhythm. The physiological relevance of Nav1.5 is further marked by the fact that inherited or congenital mutations in Nav1.5 channel gene SCN5A lead to altered functional expression (including expression, trafficking, and current density), and are generally manifested in the form of distinct cardiac arrhythmic events, epilepsy, neuropathic pain, migraine, and neuromuscular disorders. However, despite significant advances in defining the pathophysiology of Nav1.5, the molecular mechanisms that underlie its regulation and contribution to cardiac disorders are poorly understood. It is rapidly becoming evident that the functional expression (localization, trafficking and gating) of Nav1.5 may be under modulation by post-translational modifications that are associated with phosphorylation. We review here the molecular basis of cardiac Na channel regulation by kinases (PKA and PKC) and the resulting functional consequences. Specifically, we discuss: (1) recent literature on the structural, molecular, and functional properties of cardiac Nav1.5 channels; (2) how these properties may be altered by phosphorylation in disease states underlain by congenital mutations in Nav1.5 channel and/or subunits such as long QT and Brugada syndromes. Our expectation is that understanding the roles of these distinct and complex phosphorylation processes on the functional expression of Nav1.5 is likely to provide crucial mechanistic insights into Na channel associated arrhythmogenic events and will facilitate the development of novel therapeutic strategies.
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Affiliation(s)
- Ademuyiwa S Aromolaran
- Cardiovascular Research Program, VA New York Harbor Healthcare System, Brooklyn, NY, USA
- Departments of Medicine, Cell Biology and Pharmacology, State University of New York Downstate Medical Center, Brooklyn, NY, USA
| | - Mohamed Chahine
- CERVO Brain Research Center, Institut Universitaire en Santé Mentale de Québec, Quebec City, QC, Canada
- Department of Medicine, Université Laval, Quebec City, QC, Canada
| | - Mohamed Boutjdir
- Cardiovascular Research Program, VA New York Harbor Healthcare System, Brooklyn, NY, USA.
- Departments of Medicine, Cell Biology and Pharmacology, State University of New York Downstate Medical Center, Brooklyn, NY, USA.
- Department of Medicine, New York University School of Medicine, New York, NY, USA.
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33
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Lubbers ER, Mohler PJ. Roles and regulation of protein phosphatase 2A (PP2A) in the heart. J Mol Cell Cardiol 2016; 101:127-133. [PMID: 27832939 DOI: 10.1016/j.yjmcc.2016.11.003] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2016] [Revised: 10/28/2016] [Accepted: 11/03/2016] [Indexed: 01/21/2023]
Abstract
Reversible protein phosphorylation is central to a variety of cardiac processes including excitation-contraction coupling, Ca2+ handling, cell metabolism, myofilament regulation, and cell-cell communication. While kinase pathways linked with elevated adrenergic signaling have been a major focus for the cardiovascular field over the past half century, new findings support the critical role of protein phosphatases in both health and disease. Protein phosphatase 2A (PP2A) is a central cardiac phosphatase that regulates diverse myocyte functions through a host of target molecules. Notably, multiple mechanisms have evolved to dynamically tune PP2A function, including modulation of the composition, phosphorylation, methylation, and localization of PP2A holoenzyme populations. Further, aberrations in this regulation of PP2A function may contribute to cardiac pathophysiology. In summary, PP2A is a critical regulatory molecule in both health and disease, with a myriad of targets in heart. Based on their unique structure, localization, and regulatory properties, PP2A subunits represent exciting therapeutic targets to modulate altered adrenergic signaling in cardiovascular disease.
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Affiliation(s)
- Ellen R Lubbers
- Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, United States; Department of Physiology & Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, United States
| | - Peter J Mohler
- Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, United States; Department of Physiology & Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, United States; Department of Internal Medicine, Division of Cardiovascular Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, United States.
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Lorenzen-Schmidt I, Clarke SB, Pyle WG. The neglected messengers: Control of cardiac myofilaments by protein phosphatases. J Mol Cell Cardiol 2016; 101:81-89. [PMID: 27721025 DOI: 10.1016/j.yjmcc.2016.10.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Revised: 10/03/2016] [Accepted: 10/05/2016] [Indexed: 01/21/2023]
Abstract
Cardiac myofilaments act as the central contractile apparatus of heart muscle cells. Covalent modification of constituent proteins through phosphorylation is a rapid and powerful mechanism to control myofilament function, and is increasingly seen as a mechanism of disease. While the relationship between protein kinases and cardiac myofilaments has been widely examined, the impact of protein dephosphorylation by protein phosphatases is poorly understood. This review outlines the mechanisms by which the mostly widely expressed protein phosphatases in cardiac myocytes regulate myofilament function, and the emerging role of myofilament-associated protein phosphatases in heart failure. The importance of regulatory subunits and subcellular compartmentalization in determining the functional impact of protein phosphatases on myofilament and myocardial function is also discussed, as are discrepancies about the roles of protein phosphatases in regulating myofilament function. The potential for targeting these molecular messengers in the treatment of heart failure is discussed as a key future direction.
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Affiliation(s)
- Ilka Lorenzen-Schmidt
- Centre for Cardiovascular Investigations, Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Samantha B Clarke
- Centre for Cardiovascular Investigations, Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - W Glen Pyle
- Centre for Cardiovascular Investigations, Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada.
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35
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Weber S, Meyer-Roxlau S, El-Armouche A. Role of protein phosphatase inhibitor-1 in cardiac beta adrenergic pathway. J Mol Cell Cardiol 2016; 101:116-126. [PMID: 27639308 DOI: 10.1016/j.yjmcc.2016.09.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Revised: 09/05/2016] [Accepted: 09/13/2016] [Indexed: 01/08/2023]
Abstract
Phosphoproteomic studies have shown that about one third of all cardiac proteins are reversibly phosphorylated, affecting virtually every cellular signaling pathway. The reversibility of this process is orchestrated by the opposing enzymatic activity of kinases and phosphatases. Conversely, imbalances in subcellular protein phosphorylation patterns are a hallmark of many cardiovascular diseases including heart failure and cardiac arrhythmias. While numerous studies have revealed excessive beta-adrenergic signaling followed by deregulated kinase expression or activity as a major driver of the latter cardiac pathologies, far less is known about the beta-adrenergic regulation of their phosphatase counterparts. In fact, most of the limited knowledge stems from the detailed analysis of the endogenous inhibitor of the protein phosphatase 1 (I-1) in cellular and animal models. I-1 acts as a nodal point between adrenergic and putatively non-adrenergic cardiac signaling pathways and is able to influence widespread cellular functions of protein phosphatase 1 which are contributing to cardiac health and disease, e.g. Ca2+ handling, sarcomere contractility and glucose metabolism. Finally, nearly all of these studies agree that I-1 is a promising drug target on the one hand but the outcome of its pharmacological regulation maybe extremely context-dependent on the other hand, thus warranting for careful interpretation of past and future experimental results. In this respect we will: 1) comprehensively review the current knowledge about structural, functional and regulatory properties of I-1 within the heart 2) highlight current working hypothesis and potential I-1 mediated disease mechanisms 3) discuss state-of-the-art knowledge and future prospects of a potential therapeutic strategy targeting I-1 by restoring the balance of cardiac protein phosphorylation.
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Affiliation(s)
- Silvio Weber
- Department of Pharmacology and Toxicology, Medical Faculty, Technische Universität Dresden, Fetscherstraße 74, Dresden 01307, Germany.
| | - Stefanie Meyer-Roxlau
- Department of Pharmacology and Toxicology, Medical Faculty, Technische Universität Dresden, Fetscherstraße 74, Dresden 01307, Germany
| | - Ali El-Armouche
- Department of Pharmacology and Toxicology, Medical Faculty, Technische Universität Dresden, Fetscherstraße 74, Dresden 01307, Germany.
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