Submitted on July 7, 2006
Accepted on February 22, 2007
Hic-5 Promotes Endothelial Cell Migration to Lysophosphatidic Acid
Christie J Avraamides1, Michael E Bromberg2, John P Gaughan3, Sheila M Thomas4, Alexander Y Tsygankov1, and Tracee S Panetti1*
1 Microbiology and Immunology, Temple University, Philadelphia, Pennsylvania, United States
2 Department of Medicine, Temple University, Philadelphia, Pennsylvania, United States
3 Epidemiology and Biostatistics, Temple University, Philadelphia, Pennsylvania, United States
4 Cancer Biology Program, Harvard Medical School, Cambridge, Massachusetts, United States
* To whom correspondence should be addressed. E-mail: tspanetti{at}yahoo.com.
Endothelial cell migration is critical for proper blood vessel development. Signals from growth factors, and matrix proteins are integrated through focal adhesion proteins to alter cell migration. Hic-5, a paxillin family member, is enriched in the focal adhesions in bovine pulmonary artery endothelial (BPAE) cells that migrate to lysophosphatidic acid (LPA) on denatured collagen. In this study we investigate the role of Hic-5 in LPA-stimulated endothelial cell migration. LPA recruits Hic-5 to the focal adhesions and to the pseudopodia in BPAE cells plated on collagen suggesting recruitment of Hic-5 to focal adhesions is associated with endothelial cell migration. Knockdown of endogenous Hic-5 significantly decreases migration towards LPA confirming involvement of Hic-5 in migration. To address the role of Hic-5 in endothelial cell migration we exogenously expressed wild type (WT) Hic-5 and GFP Hic-5 C369A/C372A (LIM3 mutant) constructs in BPAE cells. WT Hic-5 expression increases chemotaxis of BPAE cells to LPA, while migration towards LPA of the GFP Hic-5 C369A/C372A expressing cells is similar to vector control cells. Additionally, ERK phosphorylation is enhanced in the presence of LPA in WT Hic-5 cells. A pharmacological inhibitor of MEK-kinase activity inhibits LPA-stimulated WT Hic-5 cell migration and ERK phosphorylation, suggesting Hic-5 enhances migration via MEK activation of ERK. Together these studies indicate that Hic-5, a focal adhesion protein in endothelial cells, is recruited to the pseudopodia in the presence of LPA and enhances migration.
