The nuclear receptor Rev-erbα controls circadian thermogenic plasticity

The nuclear receptor Rev-erbα, a powerful repressor of transcription, is shown to link circadian and thermogenic networks by regulating the function of brown adipose tissue. In addition to daily circadian oscillation of body temperature, mammals are able to protect their core body temperature from the cold. This study identifies the nuclear receptor Rev-erb , a repressor of transcription, as a link between circadian and thermogenic networks and body temperature rhythmicity through the regulation of brown adipose tissue function. Mice exposed to cold fare dramatically better in the morning when Rev-erbα is barely expressed than at five in the afternoon when Rev-erbα is abundant, and deletion of the Rev-erbα gene improves cold tolerance. Rev-erbα is shown to function as a physiological repressor of uncoupling protein 1 (Ucp1) in brown adipose tissue, thereby acting to maintain body temperature rhythm in an environmentally responsive manner. Circadian oscillation of body temperature is a basic, evolutionarily conserved feature of mammalian biology1. In addition, homeostatic pathways allow organisms to protect their core temperatures in response to cold exposure2. However, the mechanism responsible for coordinating daily body temperature rhythm and adaptability to environmental challenges is unknown. Here we show that the nuclear receptor Rev-erbα (also known as Nr1d1), a powerful transcriptional repressor, links circadian and thermogenic networks through the regulation of brown adipose tissue (BAT) function. Mice exposed to cold fare considerably better at 05:00 (Zeitgeber time 22) when Rev-erbα is barely expressed than at 17:00 (Zeitgeber time 10) when Rev-erbα is abundant. Deletion of Rev-erbα markedly improves cold tolerance at 17:00, indicating that overcoming Rev-erbα-dependent repression is a fundamental feature of the thermogenic response to cold. Physiological induction of uncoupling protein 1 (Ucp1) by cold temperatures is preceded by rapid downregulation of Rev-erbα in BAT. Rev-erbα represses Ucp1 in a brown-adipose-cell-autonomous manner and BAT Ucp1 levels are high in Rev-erbα-null mice, even at thermoneutrality. Genetic loss of Rev-erbα also abolishes normal rhythms of body temperature and BAT activity. Thus, Rev-erbα acts as a thermogenic focal point required for establishing and maintaining body temperature rhythm in a manner that is adaptable to environmental demands.