ORIGINAL RESEARCH – BASIC SCIENCE: Primary dermal fibroblasts derived from sdc-1 deficient mice migrate faster and have altered αv integrin function

The goal of this study is to determine whether dermal fibroblasts lacking syndecan-1 (sdc1) show differences in integrin expression and function that could contribute to the delayed skin and corneal wound healing phenotypes seen in sdc-1 null mice. Using primary dermal fibroblasts, we show that after 3 days in culture no differences in α-smooth muscle actin were detected but sdc-1 null cells expressed significantly more αv and β1 integrin than wildtype (wt) cells. Transforming growth factor β1 (TGFβ1) treatment at day 3 increased αv- and β1-integrin expression in sdc-1 null cells at day 5 whereas wt cells showed increased expression only of αv-integrin. Using time-lapse studies, we showed that the sdc-1 null fibroblasts migrate faster than wt fibroblasts, treatment with TGFβ1 increased these migration differences, and treatment with a TGFβ1 antagonist caused sdc-1 null fibroblasts to slow down and migrate at the same rate as untreated wt cells. Cell spreading studies on replated fibroblasts showed altered cell spreading and focal adhesion formation on vitronectin and fibronectin-coated surfaces. Additional time lapse studies with β1- and αv-integrin antibody antagonists, showed that wt fibroblasts expressing sdc-1 had activated integrins on their surface that impeded their migration whereas the null cells expressed αv-containing integrins which were less adhesive and enhanced cell migration. Surface expression studies showed increased surface expression of α2β1 and α3β1 on the sdc-1 null fibroblasts compared with wt fibroblasts but no significant differences in surface expression of α5β1, αvβ3, or αvβ5. Taken together, our data indicates that sdc-1 functions in the activation of αv-containing integrins and support the hypothesis that impaired wound healing phenotypes seen in sdc-1 null mice could be due to integrin-mediated defects in fibroblast migration after injury.