TY - JOUR
T1 - Variant r94c in tnnt2-encoded troponin t predisposes to pediatric restrictive cardiomyopathy and sudden death through impaired thin filament relaxation resulting in myocardial diastolic dysfunction
AU - Ezekian, Jordan E.
AU - Clippinger, Sarah R.
AU - Garcia, Jaquelin M.
AU - Yang, Qixin
AU - Denfield, Susan
AU - Jeewa, Aamir
AU - Dreyer, William J.
AU - Zou, Wenxin
AU - Fan, Yuxin
AU - Allen, Hugh D.
AU - Kim, Jeffrey J.
AU - Greenberg, Michael J.
AU - Landstrom, Andrew P.
N1 - Publisher Copyright:
© 2020 The Authors.
PY - 2020
Y1 - 2020
N2 - Background-—Pediatric-onset restrictive cardiomyopathy (RCM) is associated with high mortality, but underlying mechanisms of disease are under investigated. RCM-associated diastolic dysfunction secondary to variants in TNNT2-encoded cardiac troponin T (TNNT2) is poorly described. Methods and Results-—Genetic analysis of a proband and kindred with RCM identified TNNT2-R94C, which cosegregated in a family with 2 generations of RCM, ventricular arrhythmias, and sudden death. TNNT2-R94C was absent among large, population-based cohorts Genome Aggregation Database (gnomAD) and predicted to be pathologic by in silico modeling. Biophysical experiments using recombinant human TNNT2-R94C demonstrated impaired cardiac regulation at the molecular level attributed to reduced calcium-dependent blocking of myosin’s interaction with the thin filament. Computational modeling predicted a shift in the force-calcium curve for the R94C mutant toward submaximal calcium activation compared within the wild type, suggesting low levels of muscle activation even at resting calcium concentrations and hypercontractility following activation by calcium. Conclusions-—The pathogenic TNNT2-R94C variant activates thin-filament–mediated sarcomeric contraction at submaximal calcium concentrations, likely resulting in increased muscle tension during diastole and hypercontractility during systole. This describes the proximal biophysical mechanism for development of RCM in this family.
AB - Background-—Pediatric-onset restrictive cardiomyopathy (RCM) is associated with high mortality, but underlying mechanisms of disease are under investigated. RCM-associated diastolic dysfunction secondary to variants in TNNT2-encoded cardiac troponin T (TNNT2) is poorly described. Methods and Results-—Genetic analysis of a proband and kindred with RCM identified TNNT2-R94C, which cosegregated in a family with 2 generations of RCM, ventricular arrhythmias, and sudden death. TNNT2-R94C was absent among large, population-based cohorts Genome Aggregation Database (gnomAD) and predicted to be pathologic by in silico modeling. Biophysical experiments using recombinant human TNNT2-R94C demonstrated impaired cardiac regulation at the molecular level attributed to reduced calcium-dependent blocking of myosin’s interaction with the thin filament. Computational modeling predicted a shift in the force-calcium curve for the R94C mutant toward submaximal calcium activation compared within the wild type, suggesting low levels of muscle activation even at resting calcium concentrations and hypercontractility following activation by calcium. Conclusions-—The pathogenic TNNT2-R94C variant activates thin-filament–mediated sarcomeric contraction at submaximal calcium concentrations, likely resulting in increased muscle tension during diastole and hypercontractility during systole. This describes the proximal biophysical mechanism for development of RCM in this family.
UR - http://www.scopus.com/inward/record.url?scp=85080058202&partnerID=8YFLogxK
U2 - 10.1161/JAHA.119.015111
DO - 10.1161/JAHA.119.015111
M3 - Article
C2 - 32098556
AN - SCOPUS:85080058202
SN - 2047-9980
VL - 9
JO - Journal of the American Heart Association
JF - Journal of the American Heart Association
IS - 5
M1 - e015111
ER -