title: Soluble form of heparin-binding EGF-like growth factor contributes to retinoic acid-induced epidermal hyperplasia.
abstract: Heparin-binding EGF-like growth factor (HB-EGF), a member of the EGF-family, is thought to be important for keratinocyte functions. HB-EGF is first synthesized as a membrane-anchored form, and its soluble form is released by ectodomain shedding. Here we investigate the role of HB-EGF in epidermal hyperplasia induced by all-trans retinoic acid (tRA) treatment. HB-EGF is normally expressed in epidermis of normal adult mice at very low levels, but topical tRA treatment results in epidermal hyperplasia, concomitant with the strong induction of HB-EGF expression in the suprabasal layer. tRA-induced epidermal hyperplasia was reduced both in the keratinocyte-specific HB-EGF null mice (K5-HB(del/del)) and knock-in mice expressing the uncleavable mutant form of HB-EGF (HB(uc/uc)), as compared with wild-type HB-EGF knock-in mice (HB(lox/lox)). Among ErbB tyrosine kinase receptors, EGF receptor (EGFR) and ErbB2 were selectively activated by tRA treatment in skin from wild-type mice, while the activation of these ErbB receptors was significantly reduced in the skin of HB-EGF null mice. These results indicate that expression of HB-EGF and generation of its soluble form, followed by activation of EGFR and ErbB2, are pivotal processes in tRA-induced epidermal hyperplasia.
authors.affiliation: Department of Cell Biology, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka 565-0871, Japan.
authors.forename: Rina
authors.initials: R
authors.lastname: Kimura
authors.forename: Ryo
authors.initials: R
authors.lastname: Iwamoto
authors.forename: Eisuke
authors.initials: E
authors.lastname: Mekada
mesh_terms: D000818:Animals; D049109:Cell Proliferation / Q000187:drug effects; D004815:Epidermal Growth Factor / Q000737:chemistry / Q000378:metabolism*; D004817:Epidermis / Q000187:drug effects / Q000473:pathology*; D066246:ErbB Receptors / Q000378:metabolism; D005260:Female; D066257:Heparin-binding EGF-like Growth Factor; D006965:Hyperplasia / Q000139:chemically induced* / Q000378:metabolism; D007150:Immunohistochemistry; D036341:Intercellular Signaling Peptides and Proteins; D015603:Keratinocytes / Q000166:cytology / Q000378:metabolism; D051379:Mice; D008815:Mice, Inbred Strains; D008822:Mice, Transgenic; D012333:RNA, Messenger / Q000378:metabolism; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism; D013997:Time Factors; D014212:Tretinoin / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D004815:Epidermal Growth Factor; D066246:ErbB Receptors; D066257:Heparin-binding EGF-like Growth Factor; D036341:Intercellular Signaling Peptides and Proteins; D012333:RNA, Messenger; D018719:Erb-b2 Receptor Tyrosine Kinases; D014212:Tretinoin; C587884:Hbegf protein, mouse