Ectopic expression of LIM-nebulette (LASP2) reveals roles in cell migration and spreading

LIM-nebulette (LASP2) is a small focal adhesion protein and a member of the nebulin family of acting binding proteins. This recently identified splice variant of the nebulette locus is widely expressed andhighly enriched in neuronal tissue. Other than that LIM-nebulette is a focal adhesion protein and interacts with zyxin, nothing is known about its funciton. Given that LIM-nebulette has an identical modular organization and overlapping tissue distributions to that of LASPI, we have analyzed the role of LIM-nebulette in comparison with that of LASPI. We find that LIM-nebulette is adynamic focal adhesion protein that increases the rate of attachment and spreading a fibroblasts on fibronection coated surfaces. Additionaly, LIM-nebulette is recruited from the cortical cytoskeleton in non-mitile cells to focal adhesions at the leading edge of stimulated cells. In concluent cultures of HcLa and NIH3T3 cells. LIM-nebulette co-localizes with alpha-catenin in putative adherens junctions, whereas LASPI is devoid of these areas. Interestingly, overexpresion of LIM-nebulette in PC6 cells inhibits neurite outgrowth in response to growth factors. Collectively, our data indicate that LIM-nebulette and LAPSI have distinct roles in the actin cytoskeletoen.