title: TNF-α modulates expression of the circadian clock gene Per2 in rheumatoid synovial cells.
abstract: OBJECTIVE
  To study the effect of tumour necrosis factor (TNF)-α, responsible for the inflammation and circadian rhythm of rheumatoid arthritis (RA), on the expression of circadian clock genes in primary cultured human rheumatoid synovial cells.
  
  
  METHODS
  The expression of circadian clock genes, including circadian locomotor output cycles kaput (Clock), brain and muscle Arnt-like protein-1 (Bmal1), period (Per)1/2, and cryptochrome (Cry)1/2, and the proline and acidic amino acid-rich basic leucine zipper (PAR bZip) genes, a transcriptional activator of Per2, including D site of albumin promoter binding protein (Dbp), hepatic leukaemia factor (Hlf), and thyrotroph embryonic factor (Tef), and a transcriptional repressor of Per2, E4-binding protein 4 (E4bp4), in TNF-α-stimulated synovial cells was determined by real-time polymerase chain reaction (PCR). The D-box motifs in the Per2 promoter were mutated by site-directed mutagenesis, and the promoter activity of the Per2 gene was examined using the luciferase assay.
  
  
  RESULTS
  TNF-α enhanced the mRNA expression of Bmal1 and Cry1 but did not affect that of Clock, Per1, or Cry2. However, TNF-α inhibited the mRNA expression of the Per2 gene, as well as Dbp, Hlf, and Tef, but enhanced the mRNA expression of E4bp4. Furthermore, TNF-α inhibited the transcriptional activity of the wild-type Per2 gene in a manner dependent on the D-box 1 and D-box 2 motifs in the Per2 promoter.
  
  
  CONCLUSIONS
  TNF-α modulates the expression of the Per2 gene through the D-box binding proteins DBP, HLF, TEF, and E4BP4, in rheumatoid synovial cells, and thereby may contribute to the pathogenesis of RA.
authors.affiliation: Department of Biophysics, Kobe University Graduate School of Medicine, Kobe, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Yoshida
authors.forename: A
authors.initials: A
authors.lastname: Hashiramoto
authors.forename: T
authors.initials: T
authors.lastname: Okano
authors.forename: T
authors.initials: T
authors.lastname: Yamane
authors.forename: N
authors.initials: N
authors.lastname: Shibanuma
authors.forename: S
authors.initials: S
authors.lastname: Shiozawa
mesh_terms: D001172:Arthritis, Rheumatoid / Q000235:genetics / Q000503:physiopathology; D056926:CLOCK Proteins / Q000235:genetics*; D002478:Cells, Cultured; D057906:Circadian Clocks / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D017930:Genes, Reporter / Q000235:genetics; D006801:Humans; D016297:Mutagenesis, Site-Directed; D012333:RNA, Messenger / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D012680:Sensitivity and Specificity; D013583:Synovial Membrane / Q000166:cytology; D014162:Transfection / Q000379:methods; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000494:pharmacology*
chemical_list: D004268:DNA-Binding Proteins; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D056926:CLOCK Proteins