title: Glucocorticoids affect 24 h clock genes expression in human adipose tissue explant cultures.
abstract: OBJECTIVE
  to examine firstly whether CLOCK exhibits a circadian expression in human visceral (V) and subcutaneous (S) adipose tissue (AT) in vitro as compared with BMAL1 and PER2, and secondly to investigate the possible effect of the glucocorticoid analogue dexamethasone (DEX) on positive and negative clock genes expression.
  
  
  METHODS
  VAT and SAT biopsies were obtained from morbid obese women (body mass index ≥ 40 kg/m(2)) (n = 6). In order to investigate rhythmic expression pattern of clock genes and the effect of DEX on CLOCK, PER2 and BMAL1 expression, control AT (without DEX) and AT explants treated with DEX (2 hours) were cultured during 24 h and gene expression was analyzed at the following times: 10:00 h, 14:00 h, 18:00 h, 22:00 h, 02:00 h and 06:00 h, using qRT-PCR.
  
  
  RESULTS
  CLOCK, BMAL1 and PER2 expression exhibited circadian patterns in both VAT and SAT explants that were adjusted to a typical 24 h sinusoidal curve. PER2 expression (negative element) was in antiphase with respect to CLOCK and in phase with BMAL1 expression (both positive elements) in the SAT (situation not present in VAT). A marked effect of DEX exposure on both positive and negative clock genes expression patterns was observed. Indeed, DEX treatment modified the rhythmicity pattern towards altered patterns with a period lower than 24 hours in all genes and in both tissues.
  
  
  CONCLUSIONS
  24 h patterns in CLOCK and BMAL1 (positive clock elements) and PER2 (negative element) mRNA levels were observed in human adipose explants. These patterns were altered by dexamethasone exposure.
authors.affiliation: Department of Physiology, Faculty of Biology, University of Murcia, Murcia, Spain.
authors.forename: Purificación
authors.initials: P
authors.lastname: Gómez-Abellán
authors.forename: Antoni
authors.initials: A
authors.lastname: Díez-Noguera
authors.forename: Juan A
authors.initials: JA
authors.lastname: Madrid
authors.forename: Juan A
authors.initials: JA
authors.lastname: Luján
authors.forename: José M
authors.initials: JM
authors.lastname: Ordovás
authors.forename: Marta
authors.initials: M
authors.lastname: Garaulet
mesh_terms: D056930:ARNTL Transcription Factors / Q000235:genetics* / Q000378:metabolism; D000273:Adipose Tissue / Q000187:drug effects* / Q000378:metabolism; D000328:Adult; D015992:Body Mass Index; D056926:CLOCK Proteins / Q000235:genetics* / Q000378:metabolism; D002940:Circadian Rhythm / Q000187:drug effects* / Q000235:genetics; D003907:Dexamethasone / Q000494:pharmacology*; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D005938:Glucocorticoids / Q000494:pharmacology*; D006801:Humans; D008875:Middle Aged; D009767:Obesity, Morbid / Q000235:genetics / Q000378:metabolism; D056950:Period Circadian Proteins / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism
chemical_list: D056930:ARNTL Transcription Factors; C538960:BMAL1 protein, human; D005938:Glucocorticoids; C421902:PER2 protein, human; D056950:Period Circadian Proteins; D012333:RNA, Messenger; D003907:Dexamethasone; D056926:CLOCK Proteins; C538943:CLOCK protein, human