Lysophosphatidic acid (LPA) is a lysophospholipid mediator released after platelet activation that promotes in vivo wound healing. LPA may protect the endothelium from damage and promote repair through endothelial cell migration in Adult Respiratory Distress Syndrome (ARDS). Our data shows that LPA promotes bovine pulmonary artery endothelial cell (BPAE) migration on gelatin and collagen substrates, but not on fibronectin, fibrinogen, or vitronectin substrates. We demonstrated that recruitment of Hic-5 is a critical difference between migrating BPAE cells attached to gelatin and non-migrating BPAE cells attached to fibronectin. Hic-5 is a focal adhesion protein that is highly expressed in the lung that regulates cell adhesion and spreading. Hic-5 is recruited to the focal adhesions of migrating BPAE cells in a wound assay and to filopodia, suggesting that Hic-5 may mediate the migratory response to gelatin. The hypothesis is that LPA-stimulated endothelial cell migration requires Hic-5 in the detergent insoluble fraction of the focal adhesions.
The specific aims are: 1) to increase and decrease Hic-5 protein expression in endothelial cells to demonstrate a cause-and-effect relationship between Hic-5 and LPA-stimulated migration; 2) to examine the role of Hic-5 tyrosine phosphorylation and protein-protein interactions in regulation of endothelial cell migration through site directed mutagenesis of Hic-5; 3) to demonstrate that recruitment of Hic-5 to the detergent insoluble material is a common property for pulmonary endothelial cells; and 4) ubiquitin modification and integrin activation alter Hic-5 localization to the focal adhesion and LPA-stimulated endothelial cell migration. Previously, the role of Hic-5 in cell migration has not been examined. Therefore, these studies may provide information on target tissues that express Hic-5 and respond to LPA receptor agonists to protect the endothelium from damage in disease. Temple University provides a rich academic environment and high-quality research facilities for Dr. Panetti in the Thrombosis Research Center and Microbiology and Immunology Department. She has two independent funding sources. A critical goal of the K02 award is to implement new technology in live fluorescent imaging and siRNA. These studies will establish her independent research program.
