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Thin filament length regulation in striated muscle sarcomeres: pointed-end dynamics go beyond a nebulin ruler

Academic Article
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Overview

authors

  • Littlefield, Ryan Scott
  • Fowler, Velia

publication date

  • December 2008

journal

  • Seminars in Cell & Developmental Biology  Journal

abstract

  • The actin (thin) filaments in striated muscle are highly regulated and precisely specified in length to optimally overlap with the myosin (thick) filaments for efficient myofibril contraction. Here, we review and critically discuss recent evidence for how thin filament lengths are controlled in vertebrate skeletal, vertebrate cardiac, and invertebrate (arthropod) sarcomeres. Regulation of actin polymerization dynamics at the slow-growing (pointed) ends by the capping protein tropomodulin provides a unified explanation for how thin filament lengths are physiologically optimized in all three muscle types. Nebulin, a large protein thought to specify thin filament lengths in vertebrate skeletal muscle through a ruler mechanism, may not control pointed-end actin dynamics directly, but instead may stabilize a large core region of the thin filament. We suggest that this stabilizing function for nebulin modifies the lengths primarily specified by pointed-end actin dynamics to generate uniform filament lengths in vertebrate skeletal muscle. We suggest that nebulette, a small homolog of nebulin, may stabilize a correspondingly shorter core region and allow individual thin filament lengths to vary according to working sarcomere lengths in vertebrate cardiac muscle. We present a unified model for thin filament length regulation where these two mechanisms cooperate to tailor thin filament lengths for specific contractile environments in diverse muscles.

subject areas

  • Actin Cytoskeleton
  • Animals
  • Muscle Proteins
  • Muscle, Striated
  • Myofibrils
  • Sarcomeres
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Research

keywords

  • Actin
  • Actin monomer economy
  • Cardiac
  • Drosophila
  • Filament capping
  • Invertebrate
  • Mouse
  • Myofibril
  • Myosin
  • Nebulette
  • Rabbit
  • Skeletal
  • Sliding filament theory
  • Thick filament
  • Titin
  • Tropomodulin
  • Tropomyosin
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Identity

PubMed Central ID

  • PMC2650474

International Standard Serial Number (ISSN)

  • 1084-9521

Digital Object Identifier (DOI)

  • 10.1016/j.semcdb.2008.08.009

PubMed ID

  • 18793739
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Additional Document Info

start page

  • 511

end page

  • 519

volume

  • 19

issue

  • 6

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