title: Ephrin-A3 not only increases the density of hair follicles but also accelerates anagen development in neonatal mice.
abstract: BACKGROUND
  Ephrins are cell-membrane-bound ligands for Eph receptor tyrosine kinases (Eph). Although ephrins are known to regulate a variety of developmental processes, little is known of their role in hair development. Previously, we studied the gene expression of dermal papilla cells from androgenetic alopecia and found that ephrin-A3 was significantly down-regulated.
  
  
  OBJECTIVE
  To characterize the expression of ephrin-A3 in the hair cycle and evaluate the effect of ephrin-A3 on hair growth.
  
  
  METHODS
  We investigated gene expression and protein expression of each ephrin-As and EphAs in the skin of neonatal mice through the first and second hair cycle using quantitative PCR and immunohistochemical analysis, respectively. We also injected ephrin-A3 protein into the skin of neonatal mice and demonstrated the effect of ephrin-A3 on hair follicle development.
  
  
  RESULTS
  Expression of ephrin-A3 revealed a rapid increase at the beginning of the anagen phase, a peak during the mid-anagen, and a rapid fading during the telogen phase. In addition, we found ephrin-A3 protein was expressed in the developing hair follicles with a characteristic spatiotemporal localization. Furthermore, injection of ephrin-A3 into the skin of neonatal mice markedly accelerated the differentiation process of hair follicles. In addition, injection of ephrin-A3 unexpectedly increased the number of hair follicles.
  
  
  CONCLUSIONS
  These findings demonstrated that ephrin-A3 not only accelerates anagen development but also increases the density of hair follicles, and also suggested that an ephrin-A-EphA signal pathway is closely involved in hair follicle development.
authors.affiliation: Biological Science Research Center, Lion Corporation, Kanagawa 256-0811, Japan. yuko65@lion.co.jp
authors.forename: Yuko
authors.initials: Y
authors.lastname: Yamada
authors.forename: Tatsuyuki
authors.initials: T
authors.lastname: Midorikawa
authors.forename: Hajimu
authors.initials: H
authors.lastname: Oura
authors.forename: Teruhiko
authors.initials: T
authors.lastname: Yoshino
authors.forename: Motoyasu
authors.initials: M
authors.lastname: Ohdera
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Kubo
authors.forename: Seiji
authors.initials: S
authors.lastname: Arase
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D042783:Endothelial Cells / Q000737:chemistry; D036384:Ephrin-A3 / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D005260:Female; D018859:Hair Follicle / Q000254:growth & development*; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL
chemical_list: D036384:Ephrin-A3