MAP kinase pathways involving hsp27 regulate fibroblast-mediated wound contraction.

Background: Heat shock protein 27 (hsp27) has been shown to modulate actin arrays in a manner dependent on its phosphorylation status. Hsp27 is phosphorylated by mitogen-activated protein kinase-activated protein kinase 2/3, which is regulated by mitogen-activated protein (MAP) kinases. We hypothesize that hsp27 phosphorylation modulates wound contraction.

Materials And Methods: In these studies, a specific p38 MAP kinase inhibitor, SB203580, and a specific MAPK/extracellular signal-regulated kinase kinase 1,2 inhibitor, PD98059, were used to inhibit kinase activity. The effect of MAP kinase inhibitors was tested using a tissue culture model, the fibroblast-populated collagen lattice (FPCL) contraction assay, and a rat full-thickness skin defect model of wound healing. Hsp27 phosphorylation status was determined by isoelectric focus and Western blot analysis.

Results: We show here that hsp27 phosphorylation correlates with FPCL contraction and with contraction in vivo. In the tissue culture model, each inhibitor reduced FPCL contraction and hsp27 phosphorylation. Hsp27 phosphorylation correlated with both p38 and ERK1, 2 activation. Hsp27 was highly phosphorylated in the wound edge during wound healing in a rat in vivo model. The phosphorylation status was highest in the granulation tissue. Treatment with both kinase inhibitors significantly delayed wound contraction in vivo, which correlated with inhibition of hsp27 phosphorylation.

Conclusions: This study demonstrates that ERK and p38 kinase cascades play important roles in wound contraction. Additionally, these data implicate hsp27 as being a key molecule in modulating the effects of these kinases.