Temporal orchestration of circadian autophagy rhythm by C/EBPβ.
Level 5 - mechanism / opinion, no new human data
Bench and animal research (CEBM Level 5)
PubMed 21897364 · doi:10.1038/emboj.2011.322
What was done
Researchers investigated the circadian regulation of hepatic autophagy in mouse models and cultured primary hepatocytes. They screened transcription factors and cofactors for autophagic activity, examined C/EBPβ expression under circadian and nutritional signals, tested whether C/EBPβ activates autophagy gene expression and protein degradation in vitro, and evaluated the effect of adenoviral-mediated RNAi knockdown of C/EBPβ in vivo and liver clock deficiency in mice.
What was found
Autophagy and related gene expression showed robust circadian rhythms in mouse liver. C/EBPβ was identified as a rhythmically expressed activator of autophagy regulated by clock and nutritional signals. In primary hepatocytes, C/EBPβ stimulated autophagy gene expression and protein degradation. In vivo RNAi knockdown of C/EBPβ abolished hepatic diurnal autophagy rhythms, and mice lacking a functional liver clock showed disrupted C/EBPβ and autophagy regulation. No quantitative values or sample sizes were reported in the abstract.
Why it matters
This work identifies C/EBPβ as a key transcriptional link between the circadian clock, nutrient availability, and rhythmic autophagy in the liver.
Limits
Findings are limited to mouse models and in vitro primary hepatocyte cultures, with unclear direct applicability to human physiology. Sample sizes, quantitative effect sizes, and specific statistical parameters were not reported in the abstract.
Cited by
- supports Hepatic autophagy in mice fluctuates with circadian cycles, showing increased autophagy during the day when mice are not eating.