Gene transfer, expression, and sarcomeric incorporation of a headless myosin molecule in cardiac myocytes: Evidence for a reserve in myofilament motor function

Rene Vandenboom, Todd Herron, Elizabeth Favre, Faris P. Albayya, Joseph M. Metzger

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

The purpose of this study was to implement a living myocyte in vitro model system to test whether a motor domain-deleted headless myosin construct could be incorporated into the sarcomere and affect contractility. To this end we used gene transfer to express a "headless" myosin heavy chain (headless-MHC) in complement with the native full-length myosin motors in the cardiac sarcomere. An NH2-terminal Flag epitope was used for unique detection of the motor domain-deleted headless-MHC. Total MHC content (i.e., headless-MHC + endogenous MHC) remained constant, while expression of the headless-MHC in transduced myocytes increased from 24 to 72 h after gene transfer until values leveled off at 96 h after gene transfer, at which time the headless-MHC comprised ∼20% of total MHC. Moreover, immunofluorescence labeling and confocal imaging confirmed expression and demonstrated incorporation of the headless-MHC in the A band of the cardiac sarcomere. Functional measurements in intact myocytes showed that headless-MHC modestly reduced amplitude of dynamic twitch contractions compared with controls (P < 0.05). In chemically permeabilized myocytes, maximum steady-state isometric force and the tension-pCa relationship were unaltered by the headless-MHC. These data suggest that headless-MHC can express to 20% of total myosin and incorporate into the sarcomere yet have modest to no effects on dynamic and steady-state contractile function. This would indicate a degree of functional tolerance in the sarcomere for non-functional myosin molecules.

Original languageEnglish (US)
Pages (from-to)H574-H582
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume300
Issue number2
DOIs
StatePublished - Feb 2011

Keywords

  • Adenovirus
  • Myosin heavy chain

Fingerprint Dive into the research topics of 'Gene transfer, expression, and sarcomeric incorporation of a headless myosin molecule in cardiac myocytes: Evidence for a reserve in myofilament motor function'. Together they form a unique fingerprint.

Cite this