Nebulin plays a direct role in promoting strong actin-myosin interactions

Marie Louise Bang*, Marco Caremani, Elisabetta Brunello, Ryan Littlefield, Richard L. Lieber, Ju Chen, Vincenzo Lombardi, Marco Linari

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

55 Scopus citations

Abstract

The role of the actin filament-associated protein nebulin on mechanical and kinetic properties of the actomyosin motor was investigated in skeletal muscle of wild-type (wt) and nebulin-deficient (nebulin-/-) mice that were 1 d old, an age at which sarcomeric structure is still well preserved. In Ca 2+-activated skinned fibers from psoas muscle, we determined the Ca2+ dependence of isometric force and stiffness, the rate of force redevelopment after unloaded shortening (kTR), the power during isotonic shortening, and the unloaded shortening velocity (V0). Our results show a 65% reduction in isometric force in nebulin-/- fibers at saturating [Ca2+], whereas neither thin-filament length nor the Ca2+ sensitivity of the contractile system is affected. Stiffness measurements indicate that the reduction in isometric force is due to a reduction in the number of actin-attached myosin motors, whereas the force of the motor is unchanged. Furthermore, in nebulin-/- fibers, k TR is decreased by 57%, V0 is increased by 63%, and the maximum power is decreased by 80%. These results indicate that, in the absence of nebulin, the attachment probability of the myosin motors to actin is decreased, revealing a direct role for nebulin in promoting strong actomyosin interactions responsible for force and power production.

Original languageEnglish (US)
Pages (from-to)4117-4125
Number of pages9
JournalFASEB Journal
Volume23
Issue number12
DOIs
StatePublished - Dec 2009

Keywords

  • Cytoskeletal proteins
  • Muscle force generation
  • Muscle performance

ASJC Scopus subject areas

  • Biotechnology
  • Biochemistry
  • Molecular Biology
  • Genetics

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