Decreased force enhancement in skeletal muscle sarcomeres with a deletion in titin

Krysta Powers, Kiisa C Nishikawa, Venus Joumaa, Walter Herzog

Research output: Contribution to journalArticle

25 Scopus citations

Abstract

In the cross-bridge theory, contractile force is produced by crossbridges that form between actin and myosin filaments. However, when a contracting muscle is stretched, its active force vastly exceeds the force that can be attributed to cross-bridges. This unexplained, enhanced force has been thought to originate in the giant protein titin, which becomes stiffer in actively compared with passively stretched sarcomeres by an unknown mechanism. We investigated this mechanism using a genetic mutation (mdm) with a small but crucial deletion in the titin protein. Myofibrils from normal and mdm micewere stretched from sarcomere lengths of 2.5 to 6.0 μm. Actively stretched myofibrils from normal mice were stiffer and generated more force than passively stretched myofibrils at all sarcomere lengths. No increase in stiffness and just a small increase in force were observed in actively compared with passively stretched mdm myofibrils. These results are in agreement with the idea that titin force enhancement stiffens and stabilizes the sarcomere during contraction and that this mechanism is lost with the mdm mutation.

Original languageEnglish (US)
Pages (from-to)1311-1316
Number of pages6
JournalJournal of Experimental Biology
Volume219
Issue number9
DOIs
StatePublished - May 1 2016

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Keywords

  • Cross-bridges
  • Eccentric contractions
  • Muscular dystrophy with myositis
  • Myofibrils
  • Stiffness

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Physiology
  • Medicine(all)
  • Aquatic Science
  • Animal Science and Zoology
  • Molecular Biology
  • Insect Science

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