Protein kinase Cdelta regulates the rhythm of contractility during growth factor induced migration.

摘要

The skin is an important barrier essential for immune response. When the skin is wounded, the initial step of fibroblast migration into the tissue is required for subsequent restored and normal integrity of the skin. Fibroblasts involved in this process of wound healing require proper signaling critical for cell motility and contractions of the extracellular matrix (ECM). Furthermore, regeneration of dermal tissue represents one of the most intense anabolic processes, requiring a robust vascular system to deliver nutrients and remove dead debris. Endothelial cells are also influenced by the regulation of a provisional ECM by fibroblasts. As a reservoir of growth factors/cytokines for motility/regression, it functionally serves as a dynamic scaffold for vessels to graft into the wound to mediate angiogenesis. Both systems of angiogenesis and fibroblasts remodeling require growth factor induced regulation of motility. During growth factor induced motility, PLCy1 is activated via EGFR/VEGFR/other RTK signaling and produces diacylglycerol for coactivation of PKCdelta to regulate MLC-2 contractility in fibroblast and endothelial cells. However, the functional regulation of PKCdelta mediated contractile signaling has not been investigated fully, as it specifically relates to upstream signaling. Therefore, it is hypothesized PLCy1 dependent regulation of PKCdelta mediates force signaling in these cell types. To test this hypothesis we first investigated the consequence of PKCdelta translocation to the membrane for activation and whether localization is implicated in force regulation. To determine whether PKCdelta activation during force signaling is mediated at the membrane, PKCdelta was targeted to the membrane by engineering a K-ras farnesylation motif of the c-terminus of PKCdelta. Membrane tethering of PKCdelta led to increased directional force exertion onto the ECM/substrate, as upstream regulation is mediated by PLCy1. In addition, we also investigated, whether PKCdelta regulation was involved in endothelial capillary retraction mediated by initial dissociation signals during wound healing. Endothelial cells were allowed to form cords on Matrigel, and cords were dissociated with CXCR3 ligand, CXCXL-4 (PF4). During this cord dissociation, we found that motile contractility mediated by VEGFR signaling is partially dependent on PKCdelta. This study further supports PKCdelta as a key regulator of contractility in cell migration.