Length-dependent modulation of cytoskeletal remodeling and mechanical energetics in airway smooth muscle

Am J Respir Cell Mol Biol. 2011 Jun;44(6):888-97. doi: 10.1165/rcmb.2010-0144OC. Epub 2010 Aug 12.

Abstract

Actin cytoskeletal remodeling is an important mechanism of airway smooth muscle (ASM) contraction. We tested the hypothesis that mechanical strain modulates the cholinergic receptor-mediated cytoskeletal recruitment of actin-binding and integrin-binding proteins in intact airway smooth muscle, thereby regulating the mechanical energetics of airway smooth muscle. We found that the carbachol-stimulated cytoskeletal recruitment of actin-related protein-3 (Arp3), metavinculin, and talin were up-regulated at short muscle lengths and down-regulated at long muscle lengths, suggesting that the actin cytoskeleton--integrin complex becomes enriched in cross-linked and branched actin filaments in shortened ASM. The mechanical energy output/input ratio during sinusoidal length oscillation was dependent on muscle length, oscillatory amplitude, and cholinergic activation. The enhancing effect of cholinergic stimulation on mechanical energy output/input ratio at short and long muscle lengths may be explained by the length-dependent modulation of cytoskeletal recruitment and crossbridge cycling, respectively. We postulate that ASM functions as a hybrid biomaterial, capable of switching between operating as a cytoskeleton-based mechanical energy store at short muscle lengths to operating as an actomyosin-powered mechanical energy generator at long muscle lengths. This postulate predicts that targeting the signaling molecules involved in cytoskeletal recruitment may provide a novel approach to dilating collapsed airways in obstructive airway disease.

MeSH terms

  • Actin-Related Protein 3 / metabolism
  • Actins / chemistry
  • Animals
  • Bronchoconstriction
  • Carbachol / pharmacology
  • Cattle
  • Cross-Linking Reagents / chemistry
  • Cytoskeleton / metabolism*
  • Muscle, Smooth / metabolism*
  • Oscillometry / methods
  • Phosphorylation
  • Pulmonary Disease, Chronic Obstructive / therapy
  • Stress, Mechanical
  • Talin / metabolism
  • Trachea / metabolism
  • Vinculin / metabolism

Substances

  • Actin-Related Protein 3
  • Actins
  • Cross-Linking Reagents
  • Talin
  • metavinculin
  • Vinculin
  • Carbachol