Gene-Targeted Mice with the Human Troponin T R141W Mutation Develop Dilated Cardiomyopathy with Calcium Desensitization

Mohun Ramratnam; Guy Salama; Ravi K Sharma; David Wen Rui Wang; Stephen H Smith; Sanjay K Banerjee; Xueyin N Huang; Lindsey M Gifford; Michele L Pruce; Bethann E Gabris; Samir Saba; Sanjeev G Shroff; Ferhaan Ahmad

doi:10.1371/journal.pone.0167681

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Gene-Targeted Mice with the Human Troponin T R141W Mutation Develop Dilated Cardiomyopathy with Calcium Desensitization

Journal article

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Peer reviewed

Gene-Targeted Mice with the Human Troponin T R141W Mutation Develop Dilated Cardiomyopathy with Calcium Desensitization

Mohun Ramratnam, Guy Salama, Ravi K Sharma, David Wen Rui Wang, Stephen H Smith, Sanjay K Banerjee, Xueyin N Huang, Lindsey M Gifford, Michele L Pruce, Bethann E Gabris, …

PloS one, Vol.11(12), pp.e0167681-e0167681

2016

DOI: 10.1371/journal.pone.0167681

PMCID: PMC5147943

PMID: 27936050

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Abstract

Most studies of the mechanisms leading to hereditary dilated cardiomyopathy (DCM) have been performed in reconstituted in vitro systems. Genetically engineered murine models offer the opportunity to dissect these mechanisms in vivo. We generated a gene-targeted knock-in murine model of the autosomal dominant Arg141Trp (R141W) mutation in Tnnt2, which was first described in a human family with DCM. Mice heterozygous for the mutation (Tnnt2R141W/+) recapitulated the human phenotype, developing left ventricular dilation and reduced contractility. There was a gene dosage effect, so that the phenotype in Tnnt2R141W/+mice was attenuated by transgenic overexpression of wildtype Tnnt2 mRNA transcript. Male mice exhibited poorer survival than females. Biomechanical studies on skinned fibers from Tnnt2R141W/+ hearts showed a significant decrease in pCa50 (-log[Ca2+] required for generation of 50% of maximal force) relative to wildtype hearts, indicating Ca2+ desensitization. Optical mapping studies of Langendorff-perfused Tnnt2R141W/+ hearts showed marked increases in diastolic and peak systolic intracellular Ca2+ ([Ca2+]i), and prolonged systolic rise and diastolic fall of [Ca2+]i. Perfused Tnnt2R141W/+ hearts had slower intrinsic rates in sinus rhythm and reduced peak heart rates in response to isoproterenol. Tnnt2R141W/+ hearts exhibited a reduction in phosphorylated phospholamban relative to wildtype mice. However, crossing Tnnt2R141W/+ mice with phospholamban knockout (Pln-/-) mice, which exhibit increased Ca2+ transients and contractility, had no effect on the DCM phenotype. We conclude that the Tnnt2 R141W mutation causes a Ca2+ desensitization and mice adapt by increasing Ca2+-transient amplitudes, which impairs Ca2+ handling dynamics, metabolism and responses to β-adrenergic activation.

Animals

Calcium - metabolism

Cardiomyopathy, Dilated - genetics

Cardiomyopathy, Dilated - metabolism

Cardiomyopathy, Dilated - physiopathology

Female

Gene Knock-In Techniques

Gene Targeting

Heart - physiopathology

Humans

Male

Mice

Mice, Transgenic

Myocardial Contraction

Point Mutation

Troponin T - genetics

Details

Title: Subtitle: Gene-Targeted Mice with the Human Troponin T R141W Mutation Develop Dilated Cardiomyopathy with Calcium Desensitization
Creators: Mohun Ramratnam - University of Wisconsin–Madison
Guy Salama - University of Pittsburgh
Ravi K Sharma - University of Pittsburgh
David Wen Rui Wang - University of Pittsburgh
Stephen H Smith - University of Pittsburgh
Sanjay K Banerjee - University of Pittsburgh
Xueyin N Huang - University of Pittsburgh
Lindsey M Gifford - University of Iowa
Michele L Pruce - University of Pittsburgh
Bethann E Gabris - University of Pittsburgh
Samir Saba - University of Pittsburgh
Sanjeev G Shroff - University of Pittsburgh
Ferhaan Ahmad - University of Iowa
Resource Type: Journal article
Publication Details: PloS one, Vol.11(12), pp.e0167681-e0167681
DOI: 10.1371/journal.pone.0167681
PMID: 27936050
PMCID: PMC5147943
NLM abbreviation: PLoS One
ISSN: 1932-6203
eISSN: 1932-6203
Grant note: U01 HL108642 / NHLBI NIH HHS R21 HL109812 / NHLBI NIH HHS
Language: English
Date published: 2016
Academic Unit: Radiology; Molecular Physiology and Biophysics; Cardiovascular Medicine; Fraternal Order of Eagles Diabetes Research Center; Internal Medicine
Record Identifier: 9984297603102771

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