Normal wound healing depends on regulated movement of fibroblasts into the und, under the control of growth factors, chemokines, and matrix components. Ho ver, the mechanisms by which these factors interact to promote or limit fibrobla motility are poorly understood, compromising our ability to rationally alte wound healing. Prominent among these factors are those which activate the F receptor (EGFR). TGFalpha and heparin-binding EGF-like growth factor (HB-E ). Our long term goals are to define the specific intracellular signaling path ys which actuate EGFR-mediated motility and to determine how these pathways ar modulated by other extrinsic (chemokines) or intrinsic (aging) factors to a er the balance of cell movement into the wound. We propose to test three hypo eses that probe the molecular mechanisms by which EGFR increases fibroblast moti ty, how motility is limited, and last, how this balance is modulated by age-rel ed deficits. 1. That mobilization/activation of actin modifying proteins leads to incre ed cell motility in response to EGF. We have found that EGFR-mediated motilit requires activation of PLCgamma and hydrolysis of phospho-inositide bisphos ate (PIP2). The critical connection between this action and cell motility mach ery will be determined in fibroblasts expressing signaling-restricted motogenic nd non-motogenic EGFR variants, by ascertaining whether specific PIP2-binding tin modifying proteins are mobilized from the membrane and the effect of this activation on the cytoskeletal connections with the cell membrane. 2. That select chemokines counter EGFR-mediated motility in a growth facto specific manner. Select wound chemokines inhibit fibroblast motility and a considered critical to limiting repair and preventing excess scarring. Preliminary data show that IP-10 blocks EGFR-mediated motility of human der l fibroblasts. We will determine the molecular basis by which IP-10 modulate the motility pathway to suppress EGFR-mediated motility. 3. That decreased wound healing in aging is, in part, due to decreased mot ity response of fibroblasts secondary to decreased signal transduction of the motility pathway. Wound healing is impaired in aging, concomitant with a decrease in fibroblast response to EGF and other growth factors. We propos to demonstrate, in dermal fibroblasts from aged individuals, specific molecula signaling defects in the EGFR-mediated motility pathway which may be overco by upregulation of target molecules or direct activation of downstream process . Completion of these investigations will define an intracellular signaling n work which functions to control EGFR-mediated fibroblast motility. Understandin the balance of these cellular mechanisms is important for designing interventio to promote wound healing and to limit excess fibroblast action in scarring.
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