Circadian lipid synthesis in brown fat maintains murine body temperature during chronic cold

Significance Circadian coordination of food availability, energy expenditure, and lipid metabolism is crucial for metabolic adaptation to environmental challenges. Here, we demonstrate that chronic cold temperature causes new circadian rhythms of de novo lipogenesis in brown adipose tissue (BAT). These cyclic changes are caused by a cold-induced rhythm of transcription factor SREBP1c, which is required for maximal thermogenesis and maintenance of body temperature both at the time of the physiological circadian trough as well as when food is unavailable during chronic cold exposure. Our findings demonstrate the circadian plasticity of lipid metabolism in BAT during chronic cold and the unexpected requirement of fatty acid synthesis for chronic maintenance of thermogenesis, suggesting strategies for increasing energy expenditure to combat metabolic diseases.