Oral Presentation 2015 Annual Meeting of the Australasian Society for Dermatology Research

B-Myb Enhances Proliferation and Suppresses Differentiation of Keratinocytes in Three-dimensional Cell Culture (#16)

Hiroshi Maruyama 1 , Yosuke Ishitsuka 1 , Yasuhiro Fujisawa 1 , Junichi Furuta 1 , Mitsuru Sekido Mitsuru Sekido 1 , Yasuhiro Kawachi 1 , Manabu Fujimoto 1
  1. University of Tsukuba, Tsukuba, IBARAKI, Japan
B-Myb (Mybl2) is a member of the Myb gene family of transcription factors involved in the control of cell growth, differentiation, and apoptosis. The effects of B-Myb on keratinocyte proliferation and differentiation have not yet been clarified. The present study was performed to examine the role of B-Myb in proliferation and differentiation of the spontaneously immortalized human skin keratinocyte cell line HaCaT and normal human keratinocytes (NHK) with formation of a stratified epidermoid structure in air–liquid interface 3-dimensional culture. B-Myb was expressed specifically in undifferentiated normal keratinocytes and downregulated during differentiation. The constitutive overexpression of B-Myb in HaCaT cells during air exposure-induced differentiation resulted in an undifferentiated phenotype, i.e., thickening of the stratified layers, suppression of differentiation marker expression, and retention of proliferative activity with activation of cell cycle regulatory proteins in the S and G2/M phases. In contrast, suppression of B-Myb caused their downregulation and constrained proliferation with retention of differentiation capacity. These findings suggested that B-Myb may play an important role in maintenance of the undifferentiated phenotype of keratinocytes in the basal epidermal layer.