Friday, April 01, 2016
Mitochondrial functions regulated by body’s internal clock
Mitochondrial energy production keeps ticking by the body’s circadian clock! Past research has shown that the mitochondria generate energy at the cellular level. However, a preclinical study has indicated that mitochondrial metabolism is regulated by the body’s biological clock.
The study, published in the Proceedings of the National Academy of Sciences (PNAS), identified and quantified proteins that regulate the mitochondrial activities in mice. The team also discovered a key enzyme that determined the rate of sugar use for energy production. Dr. Gad Asher, the lead author from the Biomolecular Sciences Department of the Weizmann Institute of Science, found that the quantities of mitochondrial proteins reached a 40% peak once a day.
The investigators found that most of the circadian proteins in the mitochondria peaked at four hours into the daylight part of the day-night cycle. The mitochondrial capacity for burning sugar also peaked at the same time, which was confirmed by the peaks in respiration and glucose utilisation by the mitochondria at hour four.
Concordantly, the proteins responsible for entry and processing of fatty acids in mitochondria were found to be optimal at the same time. For the mice carrying a genetic mutation that interfered with their circadian rhythm, the amounts of proteins did not change over the course of the day, and the decomposition activity of fatty acids and sugars was steady throughout.
Commenting on the study findings, Dr. Asher said, "These findings support previous findings in our lab in which we showed that if mice eat only at night, when they are active, rather than throughout the day and night, they will eat the same amount of calories but their liver lipid levels will be 50% lower. In other words, the outcome depends not only on what you eat but also on when you eat it. If we could be more aware of the timing of our cellular activities, we might be able to take advantage of various nutrients in a healthier way."
Consequently, this study helps explain why people with eating and sleeping habits that are not in sync with their biological clocks are vulnerable to developing obesity, diabetes, and metabolic syndrome.
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