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Dilated cardiomyopathy (DCM) can be caused by a Gly159Asp mutation in cardiac troponin C (cTnC). Our previous work found that partial replacement of endogenous troponin in skinned muscle fibres with human cardiac troponin containing Gly159Asp cTnC had no significant effect on maximum force generation, Ca(2+)-sensitivity or cooperativity, but halved the activation rate. In order to examine whether the mutant affected contractility when troponin was phosphorylated, Gly159Asp cTnC was introduced in the presence of a phosphomimic of protein kinase A phosphorylation of troponin I (Ser23Asp,Ser24Asp). The increased force production of the muscle fibres caused by this phosphomimic was significantly depressed. Furthermore, in the presence of the protein kinase C phosphomimic of troponin T (Thr203Glu), Gly159Asp mutant significantly reversed the decrease in Ca(2+)-sensitivity. We conclude that this DCM mutant significantly blunts the contractile response to phosphorylation and this novel mechanism may contribute to its pathogenic effect.

Original publication

DOI

10.1016/j.bbrc.2007.05.221

Type

Journal article

Journal

Biochem Biophys Res Commun

Publication Date

17/08/2007

Volume

360

Pages

27 - 32

Keywords

Animals, Cardiomyopathy, Dilated, Cells, Cultured, Humans, Isometric Contraction, Male, Muscle Fibers, Skeletal, Muscle, Skeletal, Mutagenesis, Site-Directed, Phosphorylation, Rabbits, Troponin