title: Overexpression of CRABPI in suprabasal keratinocytes enhances the proliferation of epidermal basal keratinocytes in mouse skin topically treated with all-trans retinoic acid.
abstract: We investigated whether ectopic expression of CRABPI, a cellular retinoic acid binding protein, influenced the actions of all-trans retinoic acid (ATRA) in transgenic (TG) mice. We targeted CRABPI to the basal vs. suprabasal layers of mouse epidermis by using the keratin 14 (K14) and keratin 10 (K10) promoters, respectively. Greater CRABPI protein levels were detected in the epidermis of adult transgenic(+) mice than in transgenic(-) mice for both transgenes. In adult mouse skin CRABPI overexpression in the basal or suprabasal keratinocytes did not cause morphological abnormalities, but did result in decreased CRABPII mRNA levels. Ectopically overexpressed CRABPI in suprabasal keratinocytes, but not in basal keratinocytes, enhanced the thickening of the epidermis induced by topical ATRA treatments (10 microM, 400 microl for 4 days) by 1.59+/-0.2-fold (p<0.05). ATRA treatment (10 microM) resulted in a 59.9+/-9.8% increase (p<0.05) in the BrdU labeling index in K10/FLAG-CRABPI TG(+) mice vs. TG(-) mice. Retinoid topical treatments reduced p27 and CYP26A1 mRNA levels in TG(+) and TG(-) mouse skin in K14 and K10/FLAG-CRABPI transgenic mice. As epidermal basal keratinocyte proliferation is stimulated by paracrine growth factors secreted by ATRA activated suprabasal keratinocytes, our results indicate that CRABPI overexpression in suprabasal keratinocytes enhances the physiological functions of ATRA.
authors.affiliation: Department of Pharmacology, Weill Cornell Medical College, 1300 York Avenue, New York, NY 10021, USA.
authors.forename: Xiao-Han
authors.initials: XH
authors.lastname: Tang
authors.forename: Marina
authors.initials: M
authors.lastname: Vivero
authors.forename: Lorraine J
authors.initials: LJ
authors.lastname: Gudas
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000378:metabolism / Q000494:pharmacology; D002417:Cattle; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000235:genetics; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics; D015536:Down-Regulation / Q000235:genetics; D000078404:Epidermal Cells; D004817:Epidermis / Q000187:drug effects / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects / Q000235:genetics; D006801:Humans; D015603:Keratinocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D007633:Keratins / Q000235:genetics; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism; D018168:Receptors, Retinoic Acid / Q000235:genetics*; D000072516:Retinoic Acid 4-Hydroxylase; D014162:Transfection; D014212:Tretinoin / Q000378:metabolism* / Q000494:pharmacology; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics
chemical_list: D000970:Antineoplastic Agents; D012333:RNA, Messenger; D018168:Receptors, Retinoic Acid; C082927:retinoic acid binding protein I, cellular; D050760:Cyclin-Dependent Kinase Inhibitor p27; D014212:Tretinoin; D007633:Keratins; D003577:Cytochrome P-450 Enzyme System; C000607080:Cyp26a1 protein, mouse; D000072516:Retinoic Acid 4-Hydroxylase