title: Thrombomodulin is a clock-controlled gene in vascular endothelial cells.
abstract: Cardiovascular diseases are closely related to circadian rhythm, which is under the control of an internal biological clock mechanism. Although a biological clock exists not only in the hypothalamus but also in each peripheral tissue, the biological relevance of the peripheral clock remains to be elucidated. In this study we searched for clock-controlled genes in vascular endothelial cells using microarray technology. The expression of a total of 229 genes was up-regulated by CLOCK/BMAL2. Among the genes that we identified, we examined the thrombomodulin (TM) gene further, because TM is an integral membrane glycoprotein that is expressed primarily in vascular endothelial cells and plays a major role in the regulation of intravascular coagulation. TM mRNA and protein expression showed a clear circadian oscillation in the mouse lung and heart. Reporter analyses, gel shift assays, and chromatin immunoprecipitation analyses using the TM promoter revealed that a heterodimer of CLOCK and BMAL2 binds directly to the E-box of the TM promoter, resulting in TM promoter transactivation. Indeed, the oscillation of TM gene expression was abolished in clock mutant mice, suggesting that TM expression is regulated by the clock gene in vivo. Finally, the phase of circadian oscillation of TM mRNA expression was altered by temporal feeding restriction, suggesting TM gene expression is regulated by the peripheral clock system. In conclusion, these data suggest that the peripheral clock in vascular endothelial cells regulates TM gene expression and that the oscillation of TM expression may contribute to the circadian variation of cardiovascular events.
authors.affiliation: Department of Cardiovascular Medicine, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Norihiko
authors.initials: N
authors.lastname: Takeda
authors.forename: Koji
authors.initials: K
authors.lastname: Maemura
authors.forename: Shuichi
authors.initials: S
authors.lastname: Horie
authors.forename: Katsutaka
authors.initials: K
authors.lastname: Oishi
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Imai
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Harada
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Saito
authors.forename: Taro
authors.initials: T
authors.lastname: Shiga
authors.forename: Eisuke
authors.initials: E
authors.lastname: Amiya
authors.forename: Ichiro
authors.initials: I
authors.lastname: Manabe
authors.forename: Norio
authors.initials: N
authors.lastname: Ishida
authors.forename: Ryozo
authors.initials: R
authors.lastname: Nagai
mesh_terms: D056930:ARNTL Transcription Factors; D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism; D001683:Biological Clocks; D056926:CLOCK Proteins; D002478:Cells, Cultured; D024721:E-Box Elements; D042783:Endothelial Cells / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000235:genetics*; D006801:Humans; D008297:Male; D051379:Mice; D009154:Mutation / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D012333:RNA, Messenger / Q000235:genetics; D018180:Thrombomodulin / Q000235:genetics* / Q000378:metabolism*; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation / Q000235:genetics
chemical_list: D056930:ARNTL Transcription Factors; D051792:Basic Helix-Loop-Helix Proteins; D056926:CLOCK Proteins; D012333:RNA, Messenger; D018180:Thrombomodulin; D015534:Trans-Activators; C486615:BMAL2 protein, human; C538943:CLOCK protein, human; C538944:Clock protein, mouse