| Co-Investigator(Kenkyū-buntansha) |
YAMASAKI Kenshi Ehime University, Faculty of Medicine, Professor, 医学部, 助手 (40294798)
SHIRAKATA Yuji Ehime University, Faculty of Medicine, Instructor, 医学部, 助手 (50226320)
SAYAMA Koji Ehime University, Faculty of Medicine, Associate Professor, 医学部, 助教授 (80187286)
YOSHINO Kouichirou Nippon Organon Inc.Principle Investigator, 医薬研究所・研究開発本部, 研究部長
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| Research Abstract |
It has been reported that several EGF family are autocrine gowth factors in normal human keratinocytes (NHEK) and can induce the other EGF family known as cross-induction mechanism. To elucidate autocrine and cross-induction mechanism, we investigated the signal transduction pathways of auto- and cross-induction by HB-EGF. HB-EGF phosphorylated EGFR after 5 min, and induction of HB-EGF was inhibited by the addition of AG1483, an EGFR inhibitor. ERK, p38, and JNK were phosphorylated by the addition of HB-EGF after 10 min, suggesting the activation of all three pathways by HB-EGF. NHEK were treated with various signal transduction inhibitors ; then, the induction of EGF family mRNA was examined by RPA. The auto- and cross-induction of HB-EGF was completely blocked by treatment with curcumin, a natural JNK inhibitor, but not by p38 or MEK inhibitors. These results demonstrate that the auto- and cross-induction mechanisms of HB-EGF are mediated by the EGFR and JNK pathways. For cutaneous w
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ound healing, the most important growth factor is EGF family. HB-EGF, an autocrine growth factor in NHEK, is thought to play an important role in skin wound healing, although there have been no study about an involvement of HB-EGF in in vivo skin wound healing using mouse model. Since germline targeting of the HB-EGF gene resulted in embryonic lethality, we generated keratinocyte specific HB-EGF deficient mice (KS-HB-EGF-/-mice) using Cre/loxP technology in combination with keratin 5 promoter. A cutaneous wound was made on the mouse back skin using 6-mm punch biopsy and wound closure was measured by migration of epidermal edge stained by anti-keratin antibody. Wound closure was markedly retarded in KS-HB-EGF-/-mice compared to wild type mice on day 9. To further clarify the role of HB-EGF in cutaneous wound healing, we performed scraping wound assay using NHEK. HB-EGF mRNA was rapidly induced at 2 h after scraping, although the slight increase of TGF-alpha, amphiregulin and epiregulin m RNA was observed. Taking together, HB-EGF plays an important role in skin wound healing by accelerating keratinocyte migration. Less
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