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Garfinkel AC, Vaidya A, Strymish J, Brecher SM, Saukkonen J. From the Heart. N Engl J Med 2023; 389:e14. [PMID: 37611125 DOI: 10.1056/nejmimc2214471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
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Marston NA, Garfinkel AC, Kamanu FK, Melloni GM, Roselli C, Jarolim P, Berg DD, Bhatt DL, Bonaca MP, Cannon CP, Giugliano RP, O'Donoghue ML, Raz I, Scirica BM, Braunwald E, Morrow DA, Ellinor PT, Lubitz SA, Sabatine MS, Ruff CT. A polygenic risk score predicts atrial fibrillation in cardiovascular disease. Eur Heart J 2023; 44:221-231. [PMID: 35980763 DOI: 10.1093/eurheartj/ehac460] [Citation(s) in RCA: 21] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 07/25/2022] [Accepted: 08/05/2022] [Indexed: 01/18/2023] Open
Abstract
AIMS Interest in targeted screening programmes for atrial fibrillation (AF) has increased, yet the role of genetics in identifying patients at highest risk of developing AF is unclear. METHODS AND RESULTS A total of 36,662 subjects without prior AF were analyzed from four TIMI trials. Subjects were divided into quintiles using a validated polygenic risk score (PRS) for AF. Clinical risk for AF was calculated using the CHARGE-AF model. Kaplan-Meier event rates, adjusted hazard ratios (HRs), C-indices, and net reclassification improvement were used to determine if the addition of the PRS improved prediction compared with clinical risk and N-terminal pro-B-type natriuretic peptide (NT-proBNP). Over 2.3 years, 1018 new AF cases developed. AF PRS predicted a significant risk gradient for AF with a 40% increased risk per 1-SD increase in PRS [HR: 1.40 (1.32-1.49); P < 0.001]. Those with high AF PRS (top 20%) were more than two-fold more likely to develop AF [HR 2.45 (1.99-3.03), P < 0.001] compared with low PRS (bottom 20%). Furthermore, PRS provided an additional gradient of risk stratification on top of the CHARGE-AF clinical risk score, ranging from a 3-year incidence of 1.3% in patients with low clinical and genetic risk to 8.7% in patients with high clinical and genetic risk. The subgroup of patients with high clinical risk, high PRS, and elevated NT-proBNP had an AF risk of 16.7% over 3 years. The C-index with the CHARGE-AF clinical risk score alone was 0.65, which improved to 0.67 (P < 0.001) with the addition of NT-proBNP, and increased further to 0.70 (P < 0.001) with the addition of the PRS. CONCLUSION In patients with cardiovascular conditions, AF PRS is a strong independent predictor of incident AF that provides complementary predictive value when added to a validated clinical risk score and NT-proBNP.
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Affiliation(s)
- Nicholas A Marston
- Department for Medicine, TIMI Study Group, Boston, MA, USA.,Division of Cardiovascular Medicine, Brigham and Women's Hospital, Boston, MA, USA
| | - Amanda C Garfinkel
- Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Frederick K Kamanu
- Department for Medicine, TIMI Study Group, Boston, MA, USA.,Division of Cardiovascular Medicine, Brigham and Women's Hospital, Boston, MA, USA
| | - Giorgio M Melloni
- Department for Medicine, TIMI Study Group, Boston, MA, USA.,Division of Cardiovascular Medicine, Brigham and Women's Hospital, Boston, MA, USA
| | - Carolina Roselli
- Cardiovascular Disease Initiative, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Petr Jarolim
- Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - David D Berg
- Department for Medicine, TIMI Study Group, Boston, MA, USA.,Division of Cardiovascular Medicine, Brigham and Women's Hospital, Boston, MA, USA
| | - Deepak L Bhatt
- Division of Cardiovascular Medicine, Brigham and Women's Hospital, Boston, MA, USA
| | - Marc P Bonaca
- Department for Medicine, CPC Clinical Research, Aurora, CO, USA
| | - Christopher P Cannon
- Division of Cardiovascular Medicine, Brigham and Women's Hospital, Boston, MA, USA
| | - Robert P Giugliano
- Department for Medicine, TIMI Study Group, Boston, MA, USA.,Division of Cardiovascular Medicine, Brigham and Women's Hospital, Boston, MA, USA
| | - Michelle L O'Donoghue
- Department for Medicine, TIMI Study Group, Boston, MA, USA.,Division of Cardiovascular Medicine, Brigham and Women's Hospital, Boston, MA, USA
| | - Itamar Raz
- Department for Medicine, Hebrew University Hospital, Jerusalem, Israel
| | - Benjamin M Scirica
- Department for Medicine, TIMI Study Group, Boston, MA, USA.,Division of Cardiovascular Medicine, Brigham and Women's Hospital, Boston, MA, USA
| | - Eugene Braunwald
- Department for Medicine, TIMI Study Group, Boston, MA, USA.,Division of Cardiovascular Medicine, Brigham and Women's Hospital, Boston, MA, USA
| | - David A Morrow
- Department for Medicine, TIMI Study Group, Boston, MA, USA.,Division of Cardiovascular Medicine, Brigham and Women's Hospital, Boston, MA, USA
| | - Patrick T Ellinor
- Cardiovascular Disease Initiative, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Steven A Lubitz
- Cardiovascular Disease Initiative, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Marc S Sabatine
- Department for Medicine, TIMI Study Group, Boston, MA, USA.,Division of Cardiovascular Medicine, Brigham and Women's Hospital, Boston, MA, USA
| | - Christian T Ruff
- Department for Medicine, TIMI Study Group, Boston, MA, USA.,Division of Cardiovascular Medicine, Brigham and Women's Hospital, Boston, MA, USA
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Pua CJ, Tham N, Chin CW, Walsh R, Khor CC, Toepfer CN, Repetti GG, Garfinkel AC, Ewoldt JK, Cloonan P, Chen CS, Lim SQ, Cai J, Loo LY, Kong SC, Chiang CW, Whiffin N, de Marvao A, Lio PM, Hii AA, Yang CX, Le TT, Bylstra Y, Lim WK, Teo JX, Padilha K, Silva GV, Pan B, Govind R, Buchan RJ, Barton PJ, Tan P, Foo R, Yip JW, Wong RC, Chan WX, Pereira AC, Tang HC, Jamuar SS, Ware JS, Seidman JG, Seidman CE, Cook SA. Genetic Studies of Hypertrophic Cardiomyopathy in Singaporeans Identify Variants in TNNI3 and TNNT2 That Are Common in Chinese Patients. Circ Genom Precis Med 2020; 13:424-434. [PMID: 32815737 PMCID: PMC7676617 DOI: 10.1161/circgen.119.002823] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Accepted: 07/27/2020] [Indexed: 11/16/2022]
Abstract
BACKGROUND To assess the genetic architecture of hypertrophic cardiomyopathy (HCM) in patients of predominantly Chinese ancestry. METHODS We sequenced HCM disease genes in Singaporean patients (n=224) and Singaporean controls (n=3634), compared findings with additional populations and White HCM cohorts (n=6179), and performed in vitro functional studies. RESULTS Singaporean HCM patients had significantly fewer confidently interpreted HCM disease variants (pathogenic/likely pathogenic: 18%, P<0.0001) but an excess of variants of uncertain significance (24%, P<0.0001), as compared to Whites (pathogenic/likely pathogenic: 31%, excess of variants of uncertain significance: 7%). Two missense variants in thin filament encoding genes were commonly seen in Singaporean HCM (TNNI3:p.R79C, disease allele frequency [AF]=0.018; TNNT2:p.R286H, disease AF=0.022) and are enriched in Singaporean HCM when compared with Asian controls (TNNI3:p.R79C, Singaporean controls AF=0.0055, P=0.0057, genome aggregation database-East Asian AF=0.0062, P=0.0086; TNNT2:p.R286H, Singaporean controls AF=0.0017, P<0.0001, genome aggregation database-East Asian AF=0.0009, P<0.0001). Both these variants have conflicting annotations in ClinVar and are of low penetrance (TNNI3:p.R79C, 0.7%; TNNT2:p.R286H, 2.7%) but are predicted to be deleterious by computational tools. In population controls, TNNI3:p.R79C carriers had significantly thicker left ventricular walls compared with noncarriers while its etiological fraction is limited (0.70 [95% CI, 0.35-0.86]) and thus TNNI3:p.R79C is considered variant of uncertain significance. Mutant TNNT2:p.R286H iPSC-CMs (induced pluripotent stem cells derived cardiomyocytes) show hypercontractility, increased metabolic requirements, and cellular hypertrophy and the etiological fraction (0.93 [95% CI, 0.83-0.97]) support the likely pathogenicity of TNNT2:p.R286H. CONCLUSIONS As compared with Whites, Chinese HCM patients commonly have low penetrance risk alleles in TNNT2 or TNNI3 but exhibit few clinically actionable HCM variants overall. This highlights the need for greater study of HCM genetics in non-White populations.
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Affiliation(s)
- Chee Jian Pua
- National Heart Centre Singapore (C.J.P., N.T., C.W.L.C., S.Q.L., S.C.K., P.M.L., A.A.H., C.X.Y., T.T.L., H.C.T., S.A.C.)
- Yong Loo Lin School of Medicine, National University Singapore (C.J.P., L.Y.L.)
| | - Nevin Tham
- National Heart Centre Singapore (C.J.P., N.T., C.W.L.C., S.Q.L., S.C.K., P.M.L., A.A.H., C.X.Y., T.T.L., H.C.T., S.A.C.)
| | - Calvin W.L. Chin
- National Heart Centre Singapore (C.J.P., N.T., C.W.L.C., S.Q.L., S.C.K., P.M.L., A.A.H., C.X.Y., T.T.L., H.C.T., S.A.C.)
- Duke-National University of Singapore Medical School (C.W.L.C., J.C., S.S.J., S.A.C.)
| | - Roddy Walsh
- Department of Clinical and Experimental Cardiology, Heart Center, Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, the Netherlands (R.W.)
| | | | - Christopher N. Toepfer
- Department of Genetics, Harvard Medical School, Boston, MA (C.N.T., G.G.R., A.C.G., K.P., G.V.S., A.C.P., J.G.S., C.E.S.)
- Radcliffe Department of Medicine, University of Oxford, United Kingdom (C.N.T.)
| | - Giuliana G. Repetti
- Department of Genetics, Harvard Medical School, Boston, MA (C.N.T., G.G.R., A.C.G., K.P., G.V.S., A.C.P., J.G.S., C.E.S.)
| | - Amanda C. Garfinkel
- Department of Genetics, Harvard Medical School, Boston, MA (C.N.T., G.G.R., A.C.G., K.P., G.V.S., A.C.P., J.G.S., C.E.S.)
| | - Jourdan K. Ewoldt
- Department of Biomedical Engineering, Boston University, MA (J.K.E., P.C., C.S.C.)
| | - Paige Cloonan
- Department of Biomedical Engineering, Boston University, MA (J.K.E., P.C., C.S.C.)
| | - Christopher S. Chen
- Department of Biomedical Engineering, Boston University, MA (J.K.E., P.C., C.S.C.)
| | - Shi Qi Lim
- National Heart Centre Singapore (C.J.P., N.T., C.W.L.C., S.Q.L., S.C.K., P.M.L., A.A.H., C.X.Y., T.T.L., H.C.T., S.A.C.)
| | - Jiashen Cai
- Duke-National University of Singapore Medical School (C.W.L.C., J.C., S.S.J., S.A.C.)
| | - Li Yang Loo
- Yong Loo Lin School of Medicine, National University Singapore (C.J.P., L.Y.L.)
| | - Siew Ching Kong
- National Heart Centre Singapore (C.J.P., N.T., C.W.L.C., S.Q.L., S.C.K., P.M.L., A.A.H., C.X.Y., T.T.L., H.C.T., S.A.C.)
| | - Charleston W.K. Chiang
- Center for Genetic Epidemiology, University of Southern California (C.W.K.C.)
- Center for Neurobehavioral Genetics, University of California, Los Angeles (C.W.K.C.)
| | - Nicola Whiffin
- Cardiovascular Research Center, Royal Brompton Hospital, London, United Kingdom (N.W., A.d.M., R.G., R.J.B., P.J.R.B., J.S.W., S.A.C.)
- National Heart and Lung Institute, Imperial College London, United Kingdom (N.W., A.d.M., R.G., R.J.B., P.J.R.B., J.S.W., S.A.C.)
| | - Antonio de Marvao
- Cardiovascular Research Center, Royal Brompton Hospital, London, United Kingdom (N.W., A.d.M., R.G., R.J.B., P.J.R.B., J.S.W., S.A.C.)
- National Heart and Lung Institute, Imperial College London, United Kingdom (N.W., A.d.M., R.G., R.J.B., P.J.R.B., J.S.W., S.A.C.)
| | - Pei Min Lio
- National Heart Centre Singapore (C.J.P., N.T., C.W.L.C., S.Q.L., S.C.K., P.M.L., A.A.H., C.X.Y., T.T.L., H.C.T., S.A.C.)
| | - An An Hii
- National Heart Centre Singapore (C.J.P., N.T., C.W.L.C., S.Q.L., S.C.K., P.M.L., A.A.H., C.X.Y., T.T.L., H.C.T., S.A.C.)
| | - Cheng Xi Yang
- National Heart Centre Singapore (C.J.P., N.T., C.W.L.C., S.Q.L., S.C.K., P.M.L., A.A.H., C.X.Y., T.T.L., H.C.T., S.A.C.)
| | - Thu Thao Le
- National Heart Centre Singapore (C.J.P., N.T., C.W.L.C., S.Q.L., S.C.K., P.M.L., A.A.H., C.X.Y., T.T.L., H.C.T., S.A.C.)
| | - Yasmin Bylstra
- SingHealth/Duke-NUS Precision Medicine Inst, Singapore (Y.B., W.K.L., J.X.T., P.T., S.S.J.)
| | - Weng Khong Lim
- SingHealth/Duke-NUS Precision Medicine Inst, Singapore (Y.B., W.K.L., J.X.T., P.T., S.S.J.)
| | - Jing Xian Teo
- SingHealth/Duke-NUS Precision Medicine Inst, Singapore (Y.B., W.K.L., J.X.T., P.T., S.S.J.)
| | - Kallyandra Padilha
- Department of Genetics, Harvard Medical School, Boston, MA (C.N.T., G.G.R., A.C.G., K.P., G.V.S., A.C.P., J.G.S., C.E.S.)
- Laboratory of Genetics and Molecular Cardiology, Heart Institute (InCor)-University of São Paulo Medical School, Brazil (K.P., G.V.S., A.C.P.)
| | - Gabriela V. Silva
- Department of Genetics, Harvard Medical School, Boston, MA (C.N.T., G.G.R., A.C.G., K.P., G.V.S., A.C.P., J.G.S., C.E.S.)
- Laboratory of Genetics and Molecular Cardiology, Heart Institute (InCor)-University of São Paulo Medical School, Brazil (K.P., G.V.S., A.C.P.)
| | - Bangfen Pan
- Cardiovascular Research Institute, National University Health System, Singapore (B.P., R.F.)
| | - Risha Govind
- Cardiovascular Research Center, Royal Brompton Hospital, London, United Kingdom (N.W., A.d.M., R.G., R.J.B., P.J.R.B., J.S.W., S.A.C.)
- National Heart and Lung Institute, Imperial College London, United Kingdom (N.W., A.d.M., R.G., R.J.B., P.J.R.B., J.S.W., S.A.C.)
| | - Rachel J. Buchan
- Cardiovascular Research Center, Royal Brompton Hospital, London, United Kingdom (N.W., A.d.M., R.G., R.J.B., P.J.R.B., J.S.W., S.A.C.)
- National Heart and Lung Institute, Imperial College London, United Kingdom (N.W., A.d.M., R.G., R.J.B., P.J.R.B., J.S.W., S.A.C.)
| | - Paul J.R. Barton
- Cardiovascular Research Center, Royal Brompton Hospital, London, United Kingdom (N.W., A.d.M., R.G., R.J.B., P.J.R.B., J.S.W., S.A.C.)
- National Heart and Lung Institute, Imperial College London, United Kingdom (N.W., A.d.M., R.G., R.J.B., P.J.R.B., J.S.W., S.A.C.)
| | - Patrick Tan
- Genome Institute of Singapore (C.C.K., P.T., R.F.)
- SingHealth/Duke-NUS Precision Medicine Inst, Singapore (Y.B., W.K.L., J.X.T., P.T., S.S.J.)
| | - Roger Foo
- Genome Institute of Singapore (C.C.K., P.T., R.F.)
- Cardiovascular Research Institute, National University Health System, Singapore (B.P., R.F.)
| | - James W.L. Yip
- Cardiology Department, National University Heart Centre, Singapore (J.W.L.Y., R.C.C.W., W.X.C.)
| | - Raymond C.C. Wong
- Cardiology Department, National University Heart Centre, Singapore (J.W.L.Y., R.C.C.W., W.X.C.)
| | - Wan Xian Chan
- Cardiology Department, National University Heart Centre, Singapore (J.W.L.Y., R.C.C.W., W.X.C.)
| | - Alexandre C. Pereira
- Department of Genetics, Harvard Medical School, Boston, MA (C.N.T., G.G.R., A.C.G., K.P., G.V.S., A.C.P., J.G.S., C.E.S.)
- Laboratory of Genetics and Molecular Cardiology, Heart Institute (InCor)-University of São Paulo Medical School, Brazil (K.P., G.V.S., A.C.P.)
| | - Hak Chiaw Tang
- National Heart Centre Singapore (C.J.P., N.T., C.W.L.C., S.Q.L., S.C.K., P.M.L., A.A.H., C.X.Y., T.T.L., H.C.T., S.A.C.)
| | - Saumya Shekhar Jamuar
- Duke-National University of Singapore Medical School (C.W.L.C., J.C., S.S.J., S.A.C.)
- National Heart and Lung Institute, Imperial College London, United Kingdom (N.W., A.d.M., R.G., R.J.B., P.J.R.B., J.S.W., S.A.C.)
- KK Women’s and Children’s Hospital, Singapore (S.S.J.)
- SingHealth Duke-NUS Genomic Medicine Centre, Singapore (S.S.J.)
| | - James S. Ware
- Cardiovascular Research Center, Royal Brompton Hospital, London, United Kingdom (N.W., A.d.M., R.G., R.J.B., P.J.R.B., J.S.W., S.A.C.)
- National Heart and Lung Institute, Imperial College London, United Kingdom (N.W., A.d.M., R.G., R.J.B., P.J.R.B., J.S.W., S.A.C.)
| | - Jonathan G. Seidman
- Department of Genetics, Harvard Medical School, Boston, MA (C.N.T., G.G.R., A.C.G., K.P., G.V.S., A.C.P., J.G.S., C.E.S.)
| | - Christine E. Seidman
- Department of Genetics, Harvard Medical School, Boston, MA (C.N.T., G.G.R., A.C.G., K.P., G.V.S., A.C.P., J.G.S., C.E.S.)
- Cardiovascular Division, Brigham and Women’s Hospital, Howard Hughes Medical Institute, Boston, MA (C.E.S.)
| | - Stuart A. Cook
- National Heart Centre Singapore (C.J.P., N.T., C.W.L.C., S.Q.L., S.C.K., P.M.L., A.A.H., C.X.Y., T.T.L., H.C.T., S.A.C.)
- Duke-National University of Singapore Medical School (C.W.L.C., J.C., S.S.J., S.A.C.)
- Cardiovascular Research Center, Royal Brompton Hospital, London, United Kingdom (N.W., A.d.M., R.G., R.J.B., P.J.R.B., J.S.W., S.A.C.)
- National Heart and Lung Institute, Imperial College London, United Kingdom (N.W., A.d.M., R.G., R.J.B., P.J.R.B., J.S.W., S.A.C.)
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Toepfer CN, Garfinkel AC, Venturini G, Wakimoto H, Repetti G, Alamo L, Sharma A, Agarwal R, Ewoldt JF, Cloonan P, Letendre J, Lun M, Olivotto I, Colan S, Ashley E, Jacoby D, Michels M, Redwood CS, Watkins HC, Day SM, Staples JF, Padrón R, Chopra A, Ho CY, Chen CS, Pereira AC, Seidman JG, Seidman CE. Myosin Sequestration Regulates Sarcomere Function, Cardiomyocyte Energetics, and Metabolism, Informing the Pathogenesis of Hypertrophic Cardiomyopathy. Circulation 2020; 141:828-842. [PMID: 31983222 PMCID: PMC7077965 DOI: 10.1161/circulationaha.119.042339] [Citation(s) in RCA: 154] [Impact Index Per Article: 38.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Accepted: 12/20/2019] [Indexed: 12/15/2022]
Abstract
BACKGROUND Hypertrophic cardiomyopathy (HCM) is caused by pathogenic variants in sarcomere protein genes that evoke hypercontractility, poor relaxation, and increased energy consumption by the heart and increased patient risks for arrhythmias and heart failure. Recent studies show that pathogenic missense variants in myosin, the molecular motor of the sarcomere, are clustered in residues that participate in dynamic conformational states of sarcomere proteins. We hypothesized that these conformations are essential to adapt contractile output for energy conservation and that pathophysiology of HCM results from destabilization of these conformations. METHODS We assayed myosin ATP binding to define the proportion of myosins in the super relaxed state (SRX) conformation or the disordered relaxed state (DRX) conformation in healthy rodent and human hearts, at baseline and in response to reduced hemodynamic demands of hibernation or pathogenic HCM variants. To determine the relationships between myosin conformations, sarcomere function, and cell biology, we assessed contractility, relaxation, and cardiomyocyte morphology and metabolism, with and without an allosteric modulator of myosin ATPase activity. We then tested whether the positions of myosin variants of unknown clinical significance that were identified in patients with HCM, predicted functional consequences and associations with heart failure and arrhythmias. RESULTS Myosins undergo physiological shifts between the SRX conformation that maximizes energy conservation and the DRX conformation that enables cross-bridge formation with greater ATP consumption. Systemic hemodynamic requirements, pharmacological modulators of myosin, and pathogenic myosin missense mutations influenced the proportions of these conformations. Hibernation increased the proportion of myosins in the SRX conformation, whereas pathogenic variants destabilized these and increased the proportion of myosins in the DRX conformation, which enhanced cardiomyocyte contractility, but impaired relaxation and evoked hypertrophic remodeling with increased energetic stress. Using structural locations to stratify variants of unknown clinical significance, we showed that the variants that destabilized myosin conformations were associated with higher rates of heart failure and arrhythmias in patients with HCM. CONCLUSIONS Myosin conformations establish work-energy equipoise that is essential for life-long cellular homeostasis and heart function. Destabilization of myosin energy-conserving states promotes contractile abnormalities, morphological and metabolic remodeling, and adverse clinical outcomes in patients with HCM. Therapeutic restabilization corrects cellular contractile and metabolic phenotypes and may limit these adverse clinical outcomes in patients with HCM.
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Affiliation(s)
- Christopher N. Toepfer
- Department of Genetics, Harvard Medical School, Boston, MA (C.N.T., A.C.G., G.V., H.W., G.R., A.S., R.A., A.C.P., J.G.S., C.E.S.)
- Cardiovascular Medicine, Radcliffe Department of Medicine (C.N.T., C.S.R., H.C.W.), University of Oxford, UK
- Wellcome Centre for Human Genetics (C.N.T., H.C.W.), University of Oxford, UK
| | - Amanda C. Garfinkel
- Department of Genetics, Harvard Medical School, Boston, MA (C.N.T., A.C.G., G.V., H.W., G.R., A.S., R.A., A.C.P., J.G.S., C.E.S.)
| | - Gabriela Venturini
- Department of Genetics, Harvard Medical School, Boston, MA (C.N.T., A.C.G., G.V., H.W., G.R., A.S., R.A., A.C.P., J.G.S., C.E.S.)
- Laboratory of Genetics and Molecular Cardiology, Heart Institute (InCor)-University of São Paulo Medical School, Brazil (G.V., A.C.P.)
| | - Hiroko Wakimoto
- Department of Genetics, Harvard Medical School, Boston, MA (C.N.T., A.C.G., G.V., H.W., G.R., A.S., R.A., A.C.P., J.G.S., C.E.S.)
| | - Giuliana Repetti
- Department of Genetics, Harvard Medical School, Boston, MA (C.N.T., A.C.G., G.V., H.W., G.R., A.S., R.A., A.C.P., J.G.S., C.E.S.)
| | - Lorenzo Alamo
- Centro de Biología Estructural, Instituto Venezolano de Investigaciones Cientifìcas (IVIC), Caracas (L.A., R.P.)
| | - Arun Sharma
- Department of Genetics, Harvard Medical School, Boston, MA (C.N.T., A.C.G., G.V., H.W., G.R., A.S., R.A., A.C.P., J.G.S., C.E.S.)
| | - Radhika Agarwal
- Department of Genetics, Harvard Medical School, Boston, MA (C.N.T., A.C.G., G.V., H.W., G.R., A.S., R.A., A.C.P., J.G.S., C.E.S.)
| | - Jourdan F. Ewoldt
- Department of Biomedical Engineering, Boston University, MA (J.F.E., P.C., J.L., A.C., C.S.C.)
| | - Paige Cloonan
- Department of Biomedical Engineering, Boston University, MA (J.F.E., P.C., J.L., A.C., C.S.C.)
| | - Justin Letendre
- Department of Biomedical Engineering, Boston University, MA (J.F.E., P.C., J.L., A.C., C.S.C.)
| | - Mingyue Lun
- Department of Medicine, Division of Genetics (M.L.), Brigham and Women’s Hospital, Boston, MA
| | - Iacopo Olivotto
- Cardiomyopathy Unit and Genetic Unit, Careggi University Hospital, Florence, Italy (I.O.)
| | - Steve Colan
- Department of Cardiology, Boston Children’s Hospital, MA (S.C.)
| | - Euan Ashley
- Center for Inherited Cardiovascular Disease, Stanford University, CA (E.A.)
| | - Daniel Jacoby
- Department of Internal Medicine, Section of Cardiovascular Diseases, Yale School of Medicine, New Haven, CT (D.J.)
| | - Michelle Michels
- Department of Cardiology, Thorax Center, Erasmus MC, Rotterdam, The Netherlands (M.M.)
| | - Charles S. Redwood
- Cardiovascular Medicine, Radcliffe Department of Medicine (C.N.T., C.S.R., H.C.W.), University of Oxford, UK
| | - Hugh C. Watkins
- Cardiovascular Medicine, Radcliffe Department of Medicine (C.N.T., C.S.R., H.C.W.), University of Oxford, UK
- Wellcome Centre for Human Genetics (C.N.T., H.C.W.), University of Oxford, UK
| | - Sharlene M. Day
- Department of Internal Medicine, University of Michigan, Ann Arbor (S.M.D.)
| | - James F. Staples
- Department of Biology, University of Western Ontario, London, Canada (J.F.S.)
| | - Raúl Padrón
- Centro de Biología Estructural, Instituto Venezolano de Investigaciones Cientifìcas (IVIC), Caracas (L.A., R.P.)
- Division of Cell Biology and Imaging, Department of Radiology, University of Massachusetts Medical School, Worcester (R.P.)
| | - Anant Chopra
- Department of Biomedical Engineering, Boston University, MA (J.F.E., P.C., J.L., A.C., C.S.C.)
| | - Carolyn Y. Ho
- Cardiovascular Division (C.Y.H., C.E.S.), Brigham and Women’s Hospital, Boston, MA
| | - Christopher S. Chen
- Department of Biomedical Engineering, Boston University, MA (J.F.E., P.C., J.L., A.C., C.S.C.)
| | - Alexandre C. Pereira
- Department of Genetics, Harvard Medical School, Boston, MA (C.N.T., A.C.G., G.V., H.W., G.R., A.S., R.A., A.C.P., J.G.S., C.E.S.)
- Laboratory of Genetics and Molecular Cardiology, Heart Institute (InCor)-University of São Paulo Medical School, Brazil (G.V., A.C.P.)
| | - Jonathan G. Seidman
- Department of Genetics, Harvard Medical School, Boston, MA (C.N.T., A.C.G., G.V., H.W., G.R., A.S., R.A., A.C.P., J.G.S., C.E.S.)
| | - Christine E. Seidman
- Department of Genetics, Harvard Medical School, Boston, MA (C.N.T., A.C.G., G.V., H.W., G.R., A.S., R.A., A.C.P., J.G.S., C.E.S.)
- Cardiovascular Division (C.Y.H., C.E.S.), Brigham and Women’s Hospital, Boston, MA
- Howard Hughes Medical Institute, Chevy Chase, MD (C.E.S.)
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6
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Repetti GG, Toepfer CN, Garfinkel AC, Venturini G, Seidman JG, Seidman CE. Abstract 339: Biomechanics and Calcium Handling of Thin Filament Hypertrophic Cardiomyopathy Variants. Circ Res 2019. [DOI: 10.1161/res.125.suppl_1.339] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The mechanism by which genetic variants of the thin filament cause hypertrophic cardiomyopathy (HCM) has not been fully elucidated. Induced pluripotent stem cell (iPSC)-derived cardiomyocytes can provide a rapidly generatable disease modeling tool to study HCM in these variants. While variants in the thick and thin filament both cause HCM, cardiomyocytes that harbor pathogenic variants in the thin filament genes troponin I (
TNNI3
) and troponin T (
TNNT2
) display a distinct molecular phenotype, which we hypothesize differs from the thick filament HCM phenotype. Both thin and thick filament mutant cardiomyocytes display increased measured oxygen consumption rate assessed by metabolic assays, however we hypothesize that the mechanism that drives metabolic change is not common between thick and thin filament variants. Mutations in the thick filament typically shift myosin conformations during relaxion towards a higher energy utilizing a disordered relaxed state (DRX) that enables ATP hydrolysis with more free myosin heads, and this likely accounts for their increased oxygen consumption. However thin filament mutations cause myosin heads to preferentially adopt a conformation in which the myosin heads are sequestered and unable to bind actin. This super relaxed state (SRX) is associated with energy conservation, which would predict reduced contractility. Yet contractility data from thin filament mutants replicate the classic HCM phenotype of hypercontractility and disturbed sarcomere relaxation. To further probe the mechanism by which thin filament variants drive HCM pathophysiology we have employed methodologies to assess calcium transients in iPSC-derived cardiomyocytes harboring thin filament variants.
TNNT2
variants recapitulate this disrupted calcium handling.
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7
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Toepfer CN, Sharma A, Cicconet M, Garfinkel AC, Mücke M, Neyazi M, Willcox JA, Agarwal R, Schmid M, Rao J, Ewoldt J, Pourquié O, Chopra A, Chen CS, Seidman JG, Seidman CE. SarcTrack. Circ Res 2019; 124:1172-1183. [PMID: 30700234 PMCID: PMC6485312 DOI: 10.1161/circresaha.118.314505] [Citation(s) in RCA: 76] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 01/18/2019] [Accepted: 01/30/2019] [Indexed: 12/18/2022]
Abstract
RATIONALE Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) in combination with CRISPR/Cas9 genome editing provide unparalleled opportunities to study cardiac biology and disease. However, sarcomeres, the fundamental units of myocyte contraction, are immature and nonlinear in hiPSC-CMs, which technically challenge accurate functional interrogation of contractile parameters in beating cells. Furthermore, existing analysis methods are relatively low-throughput, indirectly assess contractility, or only assess well-aligned sarcomeres found in mature cardiac tissues. OBJECTIVE We aimed to develop an analysis platform that directly, rapidly, and automatically tracks sarcomeres in beating cardiomyocytes. The platform should assess sarcomere content, contraction and relaxation parameters, and beat rate. METHODS AND RESULTS We developed SarcTrack, a MatLab software that monitors fluorescently tagged sarcomeres in hiPSC-CMs. The algorithm determines sarcomere content, sarcomere length, and returns rates of sarcomere contraction and relaxation. By rapid measurement of hundreds of sarcomeres in each hiPSC-CM, SarcTrack provides large data sets for robust statistical analyses of multiple contractile parameters. We validated SarcTrack by analyzing drug-treated hiPSC-CMs, confirming the contractility effects of compounds that directly activate (CK-1827452) or inhibit (MYK-461) myosin molecules or indirectly alter contractility (verapamil and propranolol). SarcTrack analysis of hiPSC-CMs carrying a heterozygous truncation variant in the myosin-binding protein C ( MYBPC3) gene, which causes hypertrophic cardiomyopathy, recapitulated seminal disease phenotypes including cardiac hypercontractility and diminished relaxation, abnormalities that normalized with MYK-461 treatment. CONCLUSIONS SarcTrack provides a direct and efficient method to quantitatively assess sarcomere function. By improving existing contractility analysis methods and overcoming technical challenges associated with functional evaluation of hiPSC-CMs, SarcTrack enhances translational prospects for sarcomere-regulating therapeutics and accelerates interrogation of human cardiac genetic variants.
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Affiliation(s)
- Christopher N. Toepfer
- From the Department of Genetics (C.N.T., A.S., A.C.G., M.N., J.A.L.W., R.A., M.S., J.R., O.P., J.G.S., C.E.S.), Harvard Medical School, Boston, MA
- Cardiovascular Medicine, Radcliffe Department of Medicine (C.N.T.), University of Oxford, United Kingdom
- Wellcome Centre for Human Genetics (C.N.T.), University of Oxford, United Kingdom
| | - Arun Sharma
- From the Department of Genetics (C.N.T., A.S., A.C.G., M.N., J.A.L.W., R.A., M.S., J.R., O.P., J.G.S., C.E.S.), Harvard Medical School, Boston, MA
| | - Marcelo Cicconet
- Image and Data Analysis Core (M.C.), Harvard Medical School, Boston, MA
| | - Amanda C. Garfinkel
- From the Department of Genetics (C.N.T., A.S., A.C.G., M.N., J.A.L.W., R.A., M.S., J.R., O.P., J.G.S., C.E.S.), Harvard Medical School, Boston, MA
| | - Michael Mücke
- Cardiovascular and Metabolic Sciences, Max Delbrück Center for Molecular Medicine, Berlin, Germany (M.M.)
- German Centre for Cardiovascular Research, Berlin, Germany (M.M.)
- Charité-Universitätsmedizin, Berlin, Germany (M.M.)
| | - Meraj Neyazi
- From the Department of Genetics (C.N.T., A.S., A.C.G., M.N., J.A.L.W., R.A., M.S., J.R., O.P., J.G.S., C.E.S.), Harvard Medical School, Boston, MA
- Hannover Medical School, Germany (M.N.)
| | - Jon A.L. Willcox
- From the Department of Genetics (C.N.T., A.S., A.C.G., M.N., J.A.L.W., R.A., M.S., J.R., O.P., J.G.S., C.E.S.), Harvard Medical School, Boston, MA
| | - Radhika Agarwal
- From the Department of Genetics (C.N.T., A.S., A.C.G., M.N., J.A.L.W., R.A., M.S., J.R., O.P., J.G.S., C.E.S.), Harvard Medical School, Boston, MA
| | - Manuel Schmid
- From the Department of Genetics (C.N.T., A.S., A.C.G., M.N., J.A.L.W., R.A., M.S., J.R., O.P., J.G.S., C.E.S.), Harvard Medical School, Boston, MA
- Deutsches Herzzentrum München, Technische Universität München, Germany (M.S.)
| | - Jyoti Rao
- From the Department of Genetics (C.N.T., A.S., A.C.G., M.N., J.A.L.W., R.A., M.S., J.R., O.P., J.G.S., C.E.S.), Harvard Medical School, Boston, MA
- Department of Pathology (J.R., O.P.), Brigham and Women’s Hospital, Boston, MA
- Harvard Stem Cell Institute, Boston, MA (J.R., O.P.)
| | - Jourdan Ewoldt
- Biomedical Engineering, Boston University, MA (J.E., A.C., C.S.C.)
- The Wyss Institute for Biologically Inspired Engineering at Harvard University, Boston, MA (J.E., A.C., C.S.C.)
| | - Olivier Pourquié
- From the Department of Genetics (C.N.T., A.S., A.C.G., M.N., J.A.L.W., R.A., M.S., J.R., O.P., J.G.S., C.E.S.), Harvard Medical School, Boston, MA
- Department of Pathology (J.R., O.P.), Brigham and Women’s Hospital, Boston, MA
- Harvard Stem Cell Institute, Boston, MA (J.R., O.P.)
| | - Anant Chopra
- Biomedical Engineering, Boston University, MA (J.E., A.C., C.S.C.)
- The Wyss Institute for Biologically Inspired Engineering at Harvard University, Boston, MA (J.E., A.C., C.S.C.)
| | - Christopher S. Chen
- Biomedical Engineering, Boston University, MA (J.E., A.C., C.S.C.)
- The Wyss Institute for Biologically Inspired Engineering at Harvard University, Boston, MA (J.E., A.C., C.S.C.)
| | - Jonathan G. Seidman
- From the Department of Genetics (C.N.T., A.S., A.C.G., M.N., J.A.L.W., R.A., M.S., J.R., O.P., J.G.S., C.E.S.), Harvard Medical School, Boston, MA
| | - Christine E. Seidman
- From the Department of Genetics (C.N.T., A.S., A.C.G., M.N., J.A.L.W., R.A., M.S., J.R., O.P., J.G.S., C.E.S.), Harvard Medical School, Boston, MA
- Cardiovascular Division, Department of Medicine (C.E.S.), Brigham and Women’s Hospital, Boston, MA
- Howard Hughes Medical Institute, Chevy Chase, MD (C.E.S.)
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8
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Toepfer CN, Wakimoto H, Garfinkel AC, McDonough B, Liao D, Jiang J, Tai AC, Gorham JM, Lunde IG, Lun M, Lynch TL, McNamara JW, Sadayappan S, Redwood CS, Watkins HC, Seidman JG, Seidman CE. Hypertrophic cardiomyopathy mutations in MYBPC3 dysregulate myosin. Sci Transl Med 2019; 11:eaat1199. [PMID: 30674652 PMCID: PMC7184965 DOI: 10.1126/scitranslmed.aat1199] [Citation(s) in RCA: 109] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Revised: 06/05/2018] [Accepted: 11/30/2018] [Indexed: 12/16/2022]
Abstract
The mechanisms by which truncating mutations in MYBPC3 (encoding cardiac myosin-binding protein C; cMyBPC) or myosin missense mutations cause hypercontractility and poor relaxation in hypertrophic cardiomyopathy (HCM) are incompletely understood. Using genetic and biochemical approaches, we explored how depletion of cMyBPC altered sarcomere function. We demonstrated that stepwise loss of cMyBPC resulted in reciprocal augmentation of myosin contractility. Direct attenuation of myosin function, via a damaging missense variant (F764L) that causes dilated cardiomyopathy (DCM), normalized the increased contractility from cMyBPC depletion. Depletion of cMyBPC also altered dynamic myosin conformations during relaxation, enhancing the myosin state that enables ATP hydrolysis and thin filament interactions while reducing the super relaxed conformation associated with energy conservation. MYK-461, a pharmacologic inhibitor of myosin ATPase, rescued relaxation deficits and restored normal contractility in mouse and human cardiomyocytes with MYBPC3 mutations. These data define dosage-dependent effects of cMyBPC on myosin that occur across the cardiac cycle as the pathophysiologic mechanisms by which MYBPC3 truncations cause HCM. Therapeutic strategies to attenuate cMyBPC activity may rescue depressed cardiac contractility in patients with DCM, whereas inhibiting myosin by MYK-461 should benefit the substantial proportion of patients with HCM with MYBPC3 mutations.
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Affiliation(s)
- Christopher N Toepfer
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA.
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, OX3 9DU, UK
- Wellcome Centre for Human Genetics, University of Oxford, OX3 7BN, UK
| | - Hiroko Wakimoto
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
- Department of Cardiology, Children's Hospital Boston, Boston, MA 02115, USA
| | | | | | - Dan Liao
- Department of Biochemistry and Cardiovascular Research Institute (CVRI), Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119228, Singapore
| | - Jianming Jiang
- Department of Biochemistry and Cardiovascular Research Institute (CVRI), Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119228, Singapore
| | - Angela C Tai
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Joshua M Gorham
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Ida G Lunde
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, 0318 Oslo, Norway
| | - Mingyue Lun
- Division of Genetics, Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Thomas L Lynch
- Department of Molecular Pharmacology and Therapeutics, Health Sciences Division, Loyola University Chicago, Maywood, IL 60153, USA
| | - James W McNamara
- Heart, Lung and Vascular Institute, University of Cincinnati, Cincinnati, OH 45219, USA
| | - Sakthivel Sadayappan
- Heart, Lung and Vascular Institute, University of Cincinnati, Cincinnati, OH 45219, USA
| | - Charles S Redwood
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, OX3 9DU, UK
| | - Hugh C Watkins
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, OX3 9DU, UK
- Wellcome Centre for Human Genetics, University of Oxford, OX3 7BN, UK
| | | | - Christine E Seidman
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA.
- Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
- Division of Cardiovascular Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA
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9
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Toepfer CN, Wakimoto H, Garfinkel AC, McDonough B, Liao D, Jiang J, Tai A, Gorham J, Lund IG, Lund IG, Lun M, Lynch TL, Sadayappan S, Redwood CS, Watkins H, Seidman J, Seidman C. Abstract 571:
MYBPC3
Mutations Cause Hypertrophic Cardiomyopathy by Dysregulating Myosin: Implications for Therapy. Circ Res 2018. [DOI: 10.1161/res.123.suppl_1.571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The mechanisms by which truncating mutations in
MYBPC3
(encoding cardiac myosin binding protein-C; cMyBPC) or myosin missense mutations cause hyper-contractility and poor relaxation in hypertrophic cardiomyopathy (HCM) are incompletely understood. Using genetic and biochemical approaches we explored how depletion of cMyBPC altered sarcomere function. We demonstrate that stepwise loss of cMyBPC resulted in reciprocal augmentation of myosin contractility. Direct attenuation of myosin function, via a damaging missense variant (F764L) that causes dilated cardiomyopathy (DCM) normalized the increased contractility from cMyBPC depletion. Depletion of cMyBPC also altered dynamic myosin conformations during relaxation - enhancing the myosin state that enables ATP hydrolysis and thin filament interactions while reducing the super relaxed conformation associated with energy conservation. MYK-461, a pharmacologic inhibitor of myosin ATPase, rescued relaxation deficits and restored normal contractility in mouse and human cardiomyocytes with
MYBPC3
mutations. These data define dosage-dependent effects of cMyBPC on myosin that occur across all phases of the cardiac cycle as the pathophysiologic mechanisms by which
MYBPC3
truncations cause HCM. Therapeutic strategies to attenuate cMyBPC activity may rescue depressed cardiac contractility in DCM patients, while inhibiting myosin by MYK-461 should benefit the substantial proportion of HCM patients with
MYBPC3
mutations.
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10
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Abstract
Sarcomere cardiomyopathies are genetic diseases that perturb contractile function and lead to hypertrophic or dilated myocardial remodeling. Identification of preclinical mutation carriers has yielded insights into the earliest biomechanical defects that link pathogenic variants to cardiac dysfunction. Understanding this early molecular pathophysiology can illuminate modifiable pathways to reduce the emergence of overt cardiomyopathy and curb adverse outcomes. Here, the authors review current understandings of how human hypertrophic cardiomyopathy- and hypertrophic dilated cardiomyopathy-linked mutations disrupt the normal structure and function of the sarcomere.
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Affiliation(s)
- Amanda C Garfinkel
- Department of Genetics, Harvard Medical School, New Research Building Room 256, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
| | - Jonathan G Seidman
- Department of Genetics, Harvard Medical School, New Research Building Room 256, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
| | - Christine E Seidman
- Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, 75 Francis Street, Boston, MA 02115, USA; Department of Genetics, Brigham and Women's Hospital, Harvard Medical School, New Research Building Room 256, 77 Avenue Louis Pasteur, Boston, MA 02115, USA; Howard Hughes Medical Institute, 4000 Jones Bridge Road, Chevy Chase, MD 20815, USA.
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11
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Sharma A, Toepfer CN, Schmid M, Garfinkel AC, Seidman CE. Differentiation and Contractile Analysis of GFP-Sarcomere Reporter hiPSC-Cardiomyocytes. ACTA ACUST UNITED AC 2018; 96:21.12.1-21.12.12. [PMID: 29364522 DOI: 10.1002/cphg.53] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) represent a powerful cellular platform for illuminating mechanisms of human cardiovascular disease and for pharmacological screening. Recent advances in CRISPR/Cas9-mediated genome editing technology underlie this profound utility. We have generated hiPSC-CMs harboring fluorescently-tagged sarcomeric proteins, which provide a tool to non-invasively study human sarcomere function and dysfunction. In this unit, we illustrate methods for conducting high-efficiency, small molecule-mediated differentiation of hiPSCs into cardiomyocytes, and for performing non-invasive contractile analysis through direct sarcomere tracking of GFP-sarcomere reporter hiPSC-CMs. We believe that this type of analysis can overcome sensitivity problems found in other forms of contractile assays involving hiPSC-CMs by directly measuring contractility at the fundamental contractile unit of the hiPSC-CM, the sarcomere. © 2018 by John Wiley & Sons, Inc.
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Affiliation(s)
- Arun Sharma
- Department of Genetics, Harvard Medical School, Boston, Massachusetts
| | - Christopher N Toepfer
- Department of Genetics, Harvard Medical School, Boston, Massachusetts.,Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Manuel Schmid
- Department of Genetics, Harvard Medical School, Boston, Massachusetts.,Deutsches Herzzentrum München, Technische Universität München, Munich, Germany
| | | | - Christine E Seidman
- Department of Genetics, Harvard Medical School, Boston, Massachusetts.,Howard Hughes Medical Institute, Harvard Medical School, Boston, Massachusetts
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