title: HOXA5 inhibits keratinocytes growth and epidermal formation in organotypic cultures in vitro and in vivo.
abstract: BACKGROUND
  Homeobox transcription factors play important roles in epidermal renewal. Among them HOXA5 emerges as a promising member. However, its direct effect on epidermal biology, either to promote or to inhibit growth, is still controversial.
  
  
  OBJECTIVE
  We proposed to unravel the role of HOXA5 in modulating keratinocytes growth and epidermal formation in organotypic cultures both in vitro and in vivo.
  
  
  METHODS
  We transfected HaCaT cells with lentivirual vectors which over-expressed either wild-type or mutant HOXA5 cDNAs with deleted homeodomain. Subsequently we propagated the cells in organotypic cultures (OTCs) and then transplanted them into nude mice. Cell proliferation and cell cycle progression were detected. Epidermal morphogenesis and stratification were investigated by immunohistochemistry and immunofluorescence staining of a series of epidermal markers.
  
  
  RESULTS
  HaCaT cells transfected with HOXA5 cDNAs displayed lower growth rate and delayed G1-S transition. HOXA5-transfected OTC exhibited an aberrantly organized epithelium with significantly increased TUNEL staining as well as decreased PCNA and K5 staining, while expression of differentiation markers as K10, involucrin and filaggrin were somewhat enhanced. However, under in vivo environment in nude mice which had great paracrine regulatory mechanisms, the aberrant phenotype was ameliorated as shown by a more regular tissue organization and normal expression of PCNA and K5. Inversely, cells transfected with the homeodomain-deleted protein exhibited accelerated growth and produced a more proliferative and better-orchestrated epidermis, as shown by well-expressed proliferation and differentiation markers.
  
  
  CONCLUSIONS
  HOXA5 can suppress keratinocytes growth and epidermal formation. It probably activated antagonist genes against growth factors release, which depends on its homeodomain.
authors.affiliation: Department of Plastic and Reconstructive Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
authors.forename: Yimin
authors.initials: Y
authors.lastname: Liang
authors.forename: Lingling
authors.initials: L
authors.lastname: Xia
authors.forename: Zijing
authors.initials: Z
authors.lastname: Du
authors.forename: Lingling
authors.initials: L
authors.lastname: Sheng
authors.forename: Huili
authors.initials: H
authors.lastname: Chen
authors.forename: Gang
authors.initials: G
authors.lastname: Chen
authors.forename: Qingfeng
authors.initials: Q
authors.lastname: Li
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D049109:Cell Proliferation; D002478:Cells, Cultured; D018076:DNA, Complementary / Q000235:genetics; D004817:Epidermis / Q000254:growth & development*; D000091344:Filaggrin Proteins; D018398:Homeodomain Proteins / Q000235:genetics / Q000502:physiology*; D006801:Humans; D015603:Keratinocytes / Q000166:cytology*; D016086:Lentivirus / Q000235:genetics; D051379:Mice; D008819:Mice, Nude; D023421:Models, Animal; D009024:Morphogenesis / Q000502:physiology*; D009154:Mutation / Q000235:genetics; D009924:Organ Culture Techniques; D010641:Phenotype; D014162:Transfection; D019737:Transplants
chemical_list: D018076:DNA, Complementary; C000717249:FLG protein, human; D000091344:Filaggrin Proteins; C489213:HOXA5 protein, human; D018398:Homeodomain Proteins