A genetic risk factor for hypertension is under the control of the light/dark cycle, according to a report online this week in Nature Medicine. This observation represents a potential link between disturbances of the circadian rhythm and cardiovascular disease.
Malfunction of the circadian clock ― the 24-hour cycle that governs a large number of physiological processes in many organisms ― has been linked to a variety of diseases. Many genes have been identified as being essential elements of this molecular clock. For example, mice lacking a pair of molecules known as cryptochromes have an abnormal circadian rhythm. Hitoshi Okamura and his colleagues now show that these same mice are hypertensive due to abnormally high levels of aldosterone ― a hormone that increases kidney uptake of sodium and potassium leading to an increase in water retention.
The team went on to identify that the circadian clock directly controls a gene known as Hsd3b6 and that the product of this gene is a key element in the aldosterone-production pathway.
The authors note that in order for the relevance of these findings to be applied to human, further study of the human HSD3B1 gene, which is functionally similar to the mouse gene, is needed.