beta-Dystroglycan binds caveolin-1 in smooth muscle: a functional role in caveolae distribution and Ca2+ release

J Cell Sci. 2010 Sep 15;123(Pt 18):3061-70. doi: 10.1242/jcs.066712. Epub 2010 Aug 24.

Abstract

The dystrophin-glycoprotein complex (DGC) links the extracellular matrix and actin cytoskeleton. Caveolae form membrane arrays on smooth muscle cells; we investigated the mechanism for this organization. Caveolin-1 and beta-dystroglycan, the core transmembrane DGC subunit, colocalize in airway smooth muscle. Immunoprecipitation revealed the association of caveolin-1 with beta-dystroglycan. Disruption of actin filaments disordered caveolae arrays, reduced association of beta-dystroglycan and caveolin-1 to lipid rafts, and suppressed the sensitivity and responsiveness of methacholine-induced intracellular Ca2+ release. We generated novel human airway smooth muscle cell lines expressing shRNA to stably silence beta-dystroglycan expression. In these myocytes, caveolae arrays were disorganized, caveolae structural proteins caveolin-1 and PTRF/cavin were displaced, the signaling proteins PLCbeta1 and G(alphaq), which are required for receptor-mediated Ca2+ release, were absent from caveolae, and the sensitivity and responsiveness of methacholine-induced intracellular Ca2+ release, was diminished. These data reveal an interaction between caveolin-1 and beta-dystroglycan and demonstrate that this association, in concert with anchorage to the actin cytoskeleton, underpins the spatial organization and functional role of caveolae in receptor-mediated Ca2+ release, which is an essential initiator step in smooth muscle contraction.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium / metabolism*
  • Caveolae / metabolism*
  • Caveolin 1 / genetics
  • Caveolin 1 / metabolism*
  • Cells, Cultured
  • Cytoskeleton / genetics
  • Cytoskeleton / metabolism
  • Dogs
  • Dystroglycans / genetics
  • Dystroglycans / metabolism*
  • Humans
  • Muscle Cells / metabolism
  • Muscle, Smooth / metabolism*
  • Protein Binding

Substances

  • Caveolin 1
  • Dystroglycans
  • Calcium