title: Single Low-Dose Radiation Induced Regulation of Keratinocyte Differentiation in Calcium-Induced HaCaT Cells.
abstract: BACKGROUND
  We are continually exposed to low-dose radiation (LDR) in the range 0.1 Gy from natural sources, medical devices, nuclear energy plants, and other industrial sources of ionizing radiation. There are three models for the biological mechanism of LDR: the linear no-threshold model, the hormetic model, and the threshold model.
  
  
  OBJECTIVE
  We used keratinocytes as a model system to investigate the molecular genetic effects of LDR on epidermal cell differentiation.
  
  
  METHODS
  To identify keratinocyte differentiation, we performed western blots using a specific antibody for involucrin, which is a precursor protein of the keratinocyte cornified envelope and a marker for keratinocyte terminal differentiation. We also performed quantitative polymerase chain reaction. We examined whether LDR induces changes in involucrin messenger RNA (mRNA) and protein levels in calcium-induced keratinocyte differentiation.
  
  
  RESULTS
  Exposure of HaCaT cells to LDR (0.1 Gy) induced p21 expression. p21 is a key regulator that induces growth arrest and represses stemness, which accelerates keratinocyte differentiation. We correlated involucrin expression with keratinocyte differentiation, and examined the effects of LDR on involucrin levels and keratinocyte development. LDR significantly increased involucrin mRNA and protein levels during calcium-induced keratinocyte differentiation.
  
  
  CONCLUSIONS
  These studies provide new evidence for the biological role of LDR, and identify the potential to utilize LDR to regulate or induce keratinocyte differentiation.
authors.affiliation: Department of Dermatology, Uijeongbu St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Uijeongbu, Korea.
authors.forename: Hyung Jin
authors.initials: HJ
authors.lastname: Hahn
authors.affiliation: Department of Dermatology, Konkuk University School of Medicine, Seoul, Korea.
authors.forename: Hae Jeong
authors.initials: HJ
authors.lastname: Youn
authors.affiliation: Korea Institute for Skin and Clinical Sciences and Molecular-Targeted Drug Research Center, Konkuk University, Seoul, Korea.
authors.forename: Hwa Jun
authors.initials: HJ
authors.lastname: Cha
authors.affiliation: Korea Institute for Skin and Clinical Sciences and Molecular-Targeted Drug Research Center, Konkuk University, Seoul, Korea.
authors.forename: Karam
authors.initials: K
authors.lastname: Kim
authors.affiliation: Korea Institute for Skin and Clinical Sciences and Molecular-Targeted Drug Research Center, Konkuk University, Seoul, Korea.
authors.forename: Sungkwan
authors.initials: S
authors.lastname: An
authors.affiliation: Department of Dermatology, Konkuk University School of Medicine, Seoul, Korea.
authors.forename: Kyu Joong
authors.initials: KJ
authors.lastname: Ahn
keywords: Cell differentiation; Keratinocytes; Low-dose radiation