title: Cellular DBP and E4BP4 proteins are critical for determining the period length of the circadian oscillator.
abstract: The phenotypes of mice carrying clock gene mutations have been critical to understanding the mammalian clock function. However, behavior does not necessarily reflect cell-autonomous clock phenotypes, because of the hierarchical dominance of the central clock. We performed cell-based siRNA knockdown and cDNA overexpression and monitored rhythm using bioluminescent reporters of clock genes. We found that knockdown of DBP, D-box positive regulator, in our model led to a short-period phenotype, whereas overexpressing of DBP produced a long-period rhythm when compared to controls. Furthermore, knockdown and overexpressing of E4BP4, D-box negative regulator, led to an opposite effect of DBP. Our experiments demonstrated that D-box regulators play a crucial role in determining the period length of Per1 and Per2 promoter-driven circadian rhythms in Rat-1 fibroblasts.
authors.affiliation: Molecular Medicine Research Laboratories, Drug Discovery Research, Astellas Pharma Inc., Tsukuba, Ibaraki, Japan. daisuke.yamajuku@jp.astellas.com
authors.forename: Daisuke
authors.initials: D
authors.lastname: Yamajuku
authors.forename: Yasutaka
authors.initials: Y
authors.lastname: Shibata
authors.forename: Masashi
authors.initials: M
authors.lastname: Kitazawa
authors.forename: Toshie
authors.initials: T
authors.lastname: Katakura
authors.forename: Hiromi
authors.initials: H
authors.lastname: Urata
authors.forename: Tomoko
authors.initials: T
authors.lastname: Kojima
authors.forename: Satoko
authors.initials: S
authors.lastname: Takayasu
authors.forename: Osamu
authors.initials: O
authors.lastname: Nakata
authors.forename: Seiichi
authors.initials: S
authors.lastname: Hashimoto
mesh_terms: D000818:Animals; D050976:Basic-Leucine Zipper Transcription Factors / Q000235:genetics / Q000378:metabolism; D001683:Biological Clocks / Q000502:physiology*; D002460:Cell Line; D002940:Circadian Rhythm / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D051381:Rats; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D050976:Basic-Leucine Zipper Transcription Factors; C485975:DBP protein, rat; D004268:DNA-Binding Proteins; C558007:NFIL3 protein, rat; C497441:Nfil3 protein, mouse; D034741:RNA, Small Interfering; D012097:Repressor Proteins; D014157:Transcription Factors