2 revealed the temporal interaction between the circadian clock machinery and chaperone-mediated autophagy (CMA). To systemically profile the catabolic regulation of clock-related factors in periphery tissues, in this issue of Nature Cell Biology, Juste et al. Although the nuclear receptor REV-ERB and ROR families are reported to regulate the clock machinery at the transcriptional level, timely removal of the master clock proteins is equally important for circadian strength and periodicity 1. In both brain and peripheral tissues, the circadian rhythm is positively regulated by the transcription factors CLOCK and BMAL1, which induce expression of negative clock elements PER1, PER2, CRY1 and CRY2, forming an important negative-feedback loop. One of the key features of the circadian protein machinery is that their level or activity fluctuates to ensure precise daily oscillations. The role of CMA in different physiopathological processes has been studied for several years. The peripheral clock oscillation is influenced both by inputs from the brain and by fasting-feeding nutritional cycles. Chaperone-mediated autophagy (CMA) represents a specific way of lysosomal protein degradation and contrary to macro and microautophagy is independent of vesicles formation. In mammals, the circadian clock is centrally regulated by the suprachiasmatic nucleus of the hypothalamus, and is also located in peripheral tissues such as the liver. It controls sleep–wake cycles, metabolism and behaviours, in synchronization with the daily light–dark rhythm 1.

A highly regulated internal clock running approximately every 24 h exists in most organisms, from fruitflies to humans.

Chaperone mediated autophagy 2019