title: Low-dose ultraviolet B rays alter the mRNA expression of the circadian clock genes in cultured human keratinocytes.
abstract: Current understanding of mammalian circadian rhythms suggests that they are regulated by light targeting signaling pathways in the hypothalamic suprachiasmatic nuclei. Recently, investigators have identified the existence of extraretinal photoreceptors and a potential role for the skin in this regulatory process has been implied. We demonstrated that mRNA of the circadian clock genes Per1, Clock, and bmal1/mop3 are expressed in normal human cultured keratinocytes. Low-dose ultraviolet B rays initially downregulate all circadian clock genes and then induce altered expression of the genes in keratinocyte cell cultures. Ultraviolet light targeting superficial layers of skin (keratinocytes) may therefore contribute to circadian rhythm modulation.
authors.affiliation: Division of Dermatology, Sunnybrook & Women's College Health Sciences Center, University of Toronto, Ontario, Canada.
authors.forename: Shigeru
authors.initials: S
authors.lastname: Kawara
authors.forename: Régine
authors.initials: R
authors.lastname: Mydlarski
authors.forename: Adam J
authors.initials: AJ
authors.lastname: Mamelak
authors.forename: Irwin
authors.initials: I
authors.lastname: Freed
authors.forename: Binghe
authors.initials: B
authors.lastname: Wang
authors.forename: Hideaki
authors.initials: H
authors.lastname: Watanabe
authors.forename: Gulnar
authors.initials: G
authors.lastname: Shivji
authors.forename: Sherine K
authors.initials: SK
authors.lastname: Tavadia
authors.forename: Hirotake
authors.initials: H
authors.lastname: Suzuki
authors.forename: George A
authors.initials: GA
authors.lastname: Bjarnason
authors.forename: Richard C K
authors.initials: RC
authors.lastname: Jordan
authors.forename: Daniel N
authors.initials: DN
authors.lastname: Sauder
mesh_terms: D056930:ARNTL Transcription Factors; D051792:Basic Helix-Loop-Helix Proteins; D056926:CLOCK Proteins; D018797:Cell Cycle Proteins; D002478:Cells, Cultured; D002940:Circadian Rhythm / Q000528:radiation effects*; D015870:Gene Expression / Q000528:radiation effects; D006801:Humans; D015603:Keratinocytes / Q000166:cytology / Q000502:physiology* / Q000528:radiation effects; D009687:Nuclear Proteins / Q000235:genetics*; D056950:Period Circadian Proteins; D012333:RNA, Messenger / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics; D014466:Ultraviolet Rays
chemical_list: D056930:ARNTL Transcription Factors; D051792:Basic Helix-Loop-Helix Proteins; D056926:CLOCK Proteins; D018797:Cell Cycle Proteins; D009687:Nuclear Proteins; D056950:Period Circadian Proteins; D012333:RNA, Messenger; D015534:Trans-Activators; D014157:Transcription Factors; C538960:BMAL1 protein, human; C539022:PER1 protein, human; C538943:CLOCK protein, human