Functionally conservative substitutions at cardiac troponin I S43/45

• Published in: Archives of biochemistry and biophysics 2016-07, Vol.601, p.42-47
• Main Authors: Lang, Sarah E., Stevenson, Tamara K., Xu, Dongyang, O'Connell, Ryan, Westfall, Margaret V.
• Format: Article
• Language: English
• Subjects: Amino Acid Substitution; Animals; Calcium - chemistry; Calcium - metabolism; Epitopes - chemistry; Gene Transfer Techniques; Heart; Mutagenesis, Site-Directed; Myocardial Contraction; Myocardium - metabolism; Myocytes, Cardiac - metabolism; Myofilament; Phosphorylation; Protein Kinase C - metabolism; Rats; Rats, Sprague-Dawley; Sarcomeres - metabolism; Signal Transduction; Troponin; Troponin I - genetics; Troponin I - metabolism
• ISSN: 0003-9861; 1096-0384
• DOI: 10.1016/j.abb.2016.02.002

A phospho-null Ala substitution at protein kinase C (PKC)-targeted cardiac troponin I (cTnI) S43/45 reduces myocyte and cardiac contractile function. The goal of the current study was to test whether cTnIS43/45N is an alternative, functionally conservative substitution in cardiac myocytes. Partial and more extensive endogenous cTnI replacement was similar at 2 and 4 days after gene transfer, respectively, for epitope-tagged cTnI and cTnIS43/45N. This replacement did not significantly change thin filament stoichiometry. In functional studies, there were no significant changes in the amplitude and/or rates of contractile shortening and re-lengthening after this partial (2 days) and extensive (4 days) replacement with cTnIS43/45N. The cTnIS43/45N substitution also was not associated with adaptive changes in the myocyte Ca2+ transient or in phosphorylation of the protein kinase A and C-targeted cTnIS23/24 site. These results provide evidence that cTnIS43/45N is a functionally conservative substitution, and may be appropriate for use as a phospho-null in rodent models designed for studies on PKC modulation of cardiac performance. •Cardiac troponin I (cTnI) S43/45N is expressed in the sarcomeres of myocytes.•Thin filament stoichiometry is not changed by cTnIS43/45N expression in myocytes.•Short-term cTnIS43/45N expression in myocytes does not change contractile function.•Expression of cTnIS43/45N does not cause adaptive signaling changes in myocytes.