Thrombomodulin is a clock-controlled gene in vascular endothelial cells

Area of Science:

• Cardiovascular biology
• Chronobiology
• Molecular genetics

Background:

• Cardiovascular diseases are linked to circadian rhythms controlled by biological clocks.
• Peripheral clocks in tissues, beyond the hypothalamus, have unclear relevance.
• Understanding peripheral clock mechanisms is crucial for cardiovascular health.

Purpose of the Study:

• To identify clock-controlled genes in vascular endothelial cells.
• To investigate the regulation of thrombomodulin (TM) by circadian clock genes.
• To explore the role of peripheral clocks in cardiovascular event variations.

Main Methods:

• Microarray analysis to identify clock-controlled genes in endothelial cells.
• Analysis of thrombomodulin (TM) mRNA and protein expression in mouse tissues.
• Reporter assays, gel shift, and ChIP analyses to determine CLOCK/BMAL2 binding to the TM promoter.
• Studies in clock mutant mice and temporal feeding restriction models.

Main Results:

• Identified 229 genes, including thrombomodulin (TM), upregulated by CLOCK/BMAL2.
• Demonstrated circadian oscillation of TM mRNA and protein in mouse lung and heart.
• Confirmed direct binding of CLOCK/BMAL2 to the TM promoter, leading to transactivation.
• Showed abolished TM expression oscillation in clock mutant mice.
• Altered TM mRNA oscillation phase by temporal feeding restriction, indicating peripheral clock regulation.

Conclusions:

• The peripheral clock in vascular endothelial cells regulates thrombomodulin (TM) gene expression.
• CLOCK/BMAL2 directly binds and transactivates the TM promoter.
• Circadian TM expression oscillation, regulated by the peripheral clock, may influence cardiovascular event timing.