Micromechanical thermal assays of Ca2+-regulated thin-filament function and modulation by hypertrophic cardiomyopathy mutants of human cardiac troponin

J Biomed Biotechnol. 2012;2012:657523. doi: 10.1155/2012/657523. Epub 2012 Feb 14.

Abstract

Microfabricated thermoelectric controllers can be employed to investigate mechanisms underlying myosin-driven sliding of Ca(2+)-regulated actin and disease-associated mutations in myofilament proteins. Specifically, we examined actin filament sliding-with or without human cardiac troponin (Tn) and α-tropomyosin (Tm)-propelled by rabbit skeletal heavy meromyosin, when temperature was varied continuously over a wide range (~20-63°C). At the upper end of this temperature range, reversible dysregulation of thin filaments occurred at pCa 9 and 5; actomyosin function was unaffected. Tn-Tm enhanced sliding speed at pCa 5 and increased a transition temperature (T(t)) between a high activation energy (E(a)) but low temperature regime and a low E(a) but high temperature regime. This was modulated by factors that alter cross-bridge number and kinetics. Three familial hypertrophic cardiomyopathy (FHC) mutations, cTnI R145G, cTnI K206Q, and cTnT R278C, cause dysregulation at temperatures ~5-8°C lower; the latter two increased speed at pCa 5 at all temperatures.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Actin Cytoskeleton / metabolism*
  • Actin Cytoskeleton / physiology
  • Actins / metabolism*
  • Animals
  • Calcium / metabolism*
  • Cardiomegaly / genetics
  • Cardiomegaly / metabolism*
  • Chemistry Techniques, Analytical
  • Humans
  • Kinetics
  • Linear Models
  • Models, Biological
  • Mutation*
  • Myosin Subfragments / metabolism
  • Rabbits
  • Recombinant Proteins / metabolism
  • Temperature
  • Tropomyosin / metabolism
  • Troponin / genetics
  • Troponin / metabolism*

Substances

  • Actins
  • Myosin Subfragments
  • Recombinant Proteins
  • Tropomyosin
  • Troponin
  • Calcium