The Effects of Increased Extracellular Deformation, Pressure, and Integrin Phosphorylation on Fibroblast Migration

Wound healing requires fibroblast migration. Increased pressure slows migration and ulcer healing. Pressure also induces β1 integrin phosphorylation. We hypothesized that β1 phosphorylation influences cell adhesion and migration. We compared the effects of increased pressure on the adhesion and motility of GD25 β1-integrin null fibroblasts transfected with wild-type β1A-integrin, S785A or TT788/9AA (phosphorylation-deficient), or T788D (constitutively phosphomimetic) mutants. GD25 β1 null cells adhered less than wild type β1A cells, suggesting adherence by non-integrin mechanisms. Preventing Ser-785 or Thr 788/789 phosphorylation reduced adhesion, suggesting that phosphorylation regulates adhesiveness. Substituting Asp for Thr788 stimulated adhesion on both substrates. Pressure decreased migration in all lines and on all matrixes, the most in wild type β1A integrin cells and only slightly in β1A TT788/9AA cells. In comparison, another physical force, repetitive deformation, increased migration in the β1A integrin T788D, S785A, and wild type cells on fibronectin, and decreased migration on collagen. Deformation did not affect the migration of GD25 β1-integrin null or TT788/9AA cells. Extracellular signal-regulated kinase (ERK) blockade neither altered basal migration nor prevented pressure inhibition, while the cellular deformation response on fibronectin was altered. β1-Integrin phosphorylation regulates cellular adhesion and the deformation effects on motility. The pressure-induced motility response is independently regulated.