| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2000: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1999: ¥2,900,000 (Direct Cost: ¥2,900,000)
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| Research Abstract |
Keratinocyte proliferation and migration are essential to cutaneous wound healing and are in part mediated in an autocrine fashion by *idermal growth factor receptor (EGFR)-ligand interactions. EGFR ligands are initially synthesized as membrane-anchored forms, but can be processed and shed as soluble forms. We provide evidence here (1) that wound stimuli induce keratinocyte shedding of EGFR ligands in vitro, particularly the ligand heparin-binding EGF-like growth factor (HB-EGF). The resulting soluble ligands stimulated transient activation of EGFR and the signal transduction molecule Stat3 (signal transducer and activator of transcription 3). OSU8-1, an inhibitor of EGFR ligand shedding, abrogated the wound-induced activation of EGFR and Stat3, and caused suppression of keratinocyte migration in vitro. Soluble EGFR-Fc, which is able to neutralize all EGFR ligands, also suppressed keratinocyte migration in vitro. The application of OSU8-1 to wound sites in mice greatly retarded reepithelialization as the result of a failure in keratinocyte migration, but this effect could be overcome if recombinant soluble HB-EGF was added along with OSU8-1. These findings indicate that the shedding of EGFR ligands represents a critical event in keratinocyte migration, and suggest their possible use as an effective clinical treatment in the early phases of wound healing. 2) In oreder to identify the HB-EGF shedding enzyme, affinity cplumn *romatography was carried using biotinylated KB-R8301-Sepharose. Three RB-R8301binding proteins were purified homogeneously from the lysate of a human fibrosarcoma cell line, HT1080 cells. Primary structure analyses of them are under going.
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