Thin filament incorporation of an engineered cardiac troponin C variant (L48Q) enhances contractility in intact cardiomyocytes from healthy and infarcted hearts

Abstract Many current pharmaceutical therapies for systolic heart failure target intracellular [Ca 2 + ] ([Ca 2 + ]i ) metabolism, or cardiac troponin C (cTnC) on thin filaments, and can have significant side-effects, including arrhythmias or adverse effects on diastolic function. In this study, we...

Full description

Saved in:
Bibliographic Details
Published in:Journal of molecular and cellular cardiology 2014-07, Vol.72, p.219-227
Main Authors: Feest, Erik R, Steven Korte, F, Tu, An-yue, Dai, Jin, Razumova, Maria V, Murry, Charles E, Regnier, Michael
Format: Article
Language:English
Subjects:
Action Potentials - physiology
Adenoviridae - genetics
Adenovirus
Amino Acid Substitution
Animals
Ca2 + sensitivity
Calcium - metabolism
Cardiomyocyte contractility
Cardiomyocytes
Cardiovascular
Female
Gene Expression
Gene therapy
Genetic Therapy
Genetic Vectors
Myocardial Contraction - physiology
Myocardial infarction
Myocardial Infarction - genetics
Myocardial Infarction - metabolism
Myocardial Infarction - pathology
Myocardium - metabolism
Myocardium - pathology
Myocytes, Cardiac - metabolism
Myocytes, Cardiac - pathology
Myofibrils - genetics
Myofibrils - metabolism
Myofibrils - pathology
Primary Cell Culture
Protein Engineering
Rats
Rats, Inbred F344
Transduction, Genetic
Troponin C - genetics
Troponin C - metabolism
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Abstract Many current pharmaceutical therapies for systolic heart failure target intracellular [Ca 2 + ] ([Ca 2 + ]i ) metabolism, or cardiac troponin C (cTnC) on thin filaments, and can have significant side-effects, including arrhythmias or adverse effects on diastolic function. In this study, we tested the feasibility of directly increasing the Ca 2 + binding properties of cTnC to enhance contraction independent of [Ca 2 + ]i in intact cardiomyocytes from healthy and myocardial infarcted (MI) hearts. Specifically, cardiac thin filament activation was enhanced through adenovirus-mediated over-expression of a cardiac troponin C (cTnC) variant designed to have increased Ca 2 + binding affinity conferred by single amino acid substitution (L48Q). In skinned cardiac trabeculae and myofibrils we and others have shown that substitution of L48Q cTnC for native cTnC increases Ca 2 + sensitivity of force and the maximal rate of force development. Here we introduced L48Q cTnC into myofilaments of intact cardiomyocytes via adeno-viral transduction to deliver cDNA for the mutant or wild type (WT) cTnC protein. Using video-microscopy to monitor cell contraction, relaxation, and intracellular Ca 2 + transients (Fura-2), we report that incorporation of L48Q cTnC significantly increased contractility of cardiomyocytes from healthy and MI hearts without adversely affecting Ca 2 + transient properties or relaxation. The improvements in contractility from L48Q cTnC expression are likely the result of enhanced contractile efficiency, as intracellular Ca 2 + transient amplitudes were not affected. Expression and incorporation of L48Q cTnC into myofilaments was confirmed by Western blot analysis of myofibrils from transduced cardiomyocytes, which indicated replacement of 18 ± 2% of native cTnC with L48Q cTnC. These experiments demonstrate the feasibility of directly targeting cardiac thin filament proteins to enhance cardiomyocyte contractility that is impaired following MI.
ISSN:0022-2828
1095-8584
DOI:10.1016/j.yjmcc.2014.03.015