The small heat shock protein (HSP) 20 is dynamically associated with the actin cross-linking protein actinin

J Surg Res. 2003 May 1;111(1):152-7. doi: 10.1016/s0022-4804(03)00113-6.


Background: The heat shock-related protein (HSP) 20 is associated with actin and modulates smooth-muscle relaxation. We hypothesized that HSP20 mediates vasorelaxation via dynamic interactions with cytoskeletal proteins, such as actin, or actin binding proteins, such as alpha-actinin.

Methods: Physiological responses of strips of bovine carotid artery were analyzed with a muscle bath. In other experiments, the arteries were homogenized, and imunoprecipitations were performed. Immunohistochemistry with anti-HSP20 and anti-actinin antibodies was used to determine co-localization of the two proteins.

Results: Bovine carotid arteries contracted in response to serotonin and rapidly relaxed in response to forskolin. HSP20 co-immunoprecipitated with both actin and alpha-actinin, but not with HSP27 or paxillin. Immunostaining with HSP20 and alpha-actinin antibodies demonstrated that HSP20 and alpha-actinin co-localized. The amount of HSP20 that immunoprecipitated with alpha -actinin was markedly diminished in muscles that were treated with the vasorelaxant forskolin.

Conclusions: HSP20 is associated with both actin and alpha-actinin. Activation of cyclic nucleotide-dependent signaling pathways leads to increases in the phosphorylation of HSP20 and a decrease in the association of HSP20 with alpha-actinin. These data suggest that phosphorylation of HSP20 may lead to relaxation of vascular smooth muscles through a dynamic association with cytoskeletal elements.

MeSH terms

  • Actinin / analysis*
  • Actinin / metabolism
  • Actins / analysis
  • Animals
  • Carotid Arteries
  • Cattle
  • Colforsin / pharmacology
  • HSP20 Heat-Shock Proteins
  • Heat-Shock Proteins / analysis*
  • Heat-Shock Proteins / metabolism
  • Immunohistochemistry
  • Immunosorbent Techniques
  • Muscle Contraction / drug effects
  • Muscle Relaxation / drug effects
  • Muscle, Smooth, Vascular / chemistry*
  • Muscle, Smooth, Vascular / physiology
  • Phosphoproteins / analysis*
  • Phosphoproteins / metabolism
  • Phosphorylation
  • Serotonin / pharmacology


  • Actins
  • HSP20 Heat-Shock Proteins
  • Heat-Shock Proteins
  • Phosphoproteins
  • Actinin
  • Colforsin
  • Serotonin