NHLBI IN THE PRESS

Biological clock protects heart from radiation damage in mice

The body’s biological clock, which keeps our 24-hour rest and wake cycle intact, may be key to preventing heart cells from damage and heart failure when using radiation to treat breast cancer.

Researchers used echocardiography to compare heart function among mice, both before and six weeks after exposing the heart to radiation. One group of mice had a mutation in the PER1 and PER2 genes, which control the body’s master clock. The second group of mice had altered light-dark cycles to throw off their clocks.

The hearts from the clock-disrupted groups had difficulties pumping blood out of the heart and into the circulation due to loss of elasticity in the heart ventricle. These mice also had more heart scar tissue compared to mice with healthy biological clocks.

Researchers also showed that levels of the biological clock protein Bmal1 protein in the course of a day were significantly lower in clock-disrupted mice. Higher levels of Bmal1 protein was associated with lower DNA damage levels, and that it also interacted with BRCA1, BRCA2, and ATM genes, which help fight radiation induced cell death.

The researchers’ next step is to repeat the study in a cancer model to pinpoint the mechanism by which the biological clock protects the heart from radiation damage. The study, published in the FASEB Journal, was partly funded by NHLBI.