title: Fragile X-related proteins regulate mammalian circadian behavioral rhythms.
abstract: Fragile X syndrome results from the absence of the fragile X mental retardation 1 (FMR1) gene product (FMRP). FMR1 has two paralogs in vertebrates: fragile X related gene 1 and 2 (FXR1 and FXR2). Here we show that Fmr1/Fxr2 double knockout (KO) and Fmr1 KO/Fxr2 heterozygous animals exhibit a loss of rhythmic activity in a light:dark (LD) cycle, and that Fmr1 or Fxr2 KO mice display a shorter free-running period of locomotor activity in total darkness (DD). Molecular analysis and in vitro electrophysiological studies suggest essentially normal function of cells in the suprachiasmatic nucleus (SCN) in Fmr1/Fxr2 double KO mice. However, the cyclical patterns of abundance of several core clock component messenger (m) RNAs are altered in the livers of double KO mice. Furthermore, FXR2P alone or FMRP and FXR2P together can increase PER1- or PER2-mediated BMAL1-Neuronal PAS2 (NPAS2) transcriptional activity in a dose-dependent manner. These data collectively demonstrate that FMR1 and FXR2 are required for the presence of rhythmic circadian behavior in mammals and suggest that this role may be relevant to sleep and other behavioral alterations observed in fragile X patients.
authors.affiliation: Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA.
authors.forename: Jing
authors.initials: J
authors.lastname: Zhang
authors.forename: Zhe
authors.initials: Z
authors.lastname: Fang
authors.forename: Corinne
authors.initials: C
authors.lastname: Jud
authors.forename: Mariska J
authors.initials: MJ
authors.lastname: Vansteensel
authors.forename: Krista
authors.initials: K
authors.lastname: Kaasik
authors.forename: Cheng Chi
authors.initials: CC
authors.lastname: Lee
authors.forename: Urs
authors.initials: U
authors.lastname: Albrecht
authors.forename: Filippo
authors.initials: F
authors.lastname: Tamanini
authors.forename: Johanna H
authors.initials: JH
authors.lastname: Meijer
authors.forename: Ben A
authors.initials: BA
authors.lastname: Oostra
authors.forename: David L
authors.initials: DL
authors.lastname: Nelson
mesh_terms: D056930:ARNTL Transcription Factors; D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism; D001522:Behavior, Animal; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D002940:Circadian Rhythm / Q000235:genetics*; D056931:Cryptochromes; D004594:Electrophysiology; D005420:Flavoproteins / Q000378:metabolism; D005600:Fragile X Syndrome; D005786:Gene Expression Regulation / Q000235:genetics; D006579:Heterozygote; D017403:In Situ Hybridization; D008099:Liver / Q000737:chemistry; D008297:Male; D008322:Mammals / Q000235:genetics; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009043:Motor Activity; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D009474:Neurons / Q000502:physiology; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D056950:Period Circadian Proteins; D012333:RNA, Messenger / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics*; D013493:Suprachiasmatic Nucleus / Q000166:cytology / Q000378:metabolism; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D056930:ARNTL Transcription Factors; D051792:Basic Helix-Loop-Helix Proteins; D018797:Cell Cycle Proteins; D056931:Cryptochromes; D005420:Flavoproteins; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D056950:Period Circadian Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D014157:Transcription Factors; C538960:BMAL1 protein, human; C538961:Bmal1 protein, mouse; C512309:FXR2 protein, mouse; C496283:Fxr1h protein, mouse; C491259:Npas2 protein, mouse; C539022:PER1 protein, human; C539023:Per1 protein, mouse; C513312:Per2 protein, mouse