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J Surg Res. 2003 May 1;111(1):152-7.

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

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Department of Surgery, Division of Vascular Surgery, Mayo Clinic Scottsdale, Scottsdale, AZ, USA.



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.


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.


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.


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.

[Indexed for MEDLINE]

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