Reprogramming of the circadian clock by nutritional challenge

Area of Science:

• Metabolic pathways
• Chronobiology
• Liver clock regulation

Background:

• Circadian rhythms and cellular metabolism are closely interconnected.
• Dietary interventions can profoundly impact physiological processes.

Purpose of the Study:

• To investigate how a high-fat diet (HFD) reorganizes liver metabolic pathways and the liver clock.
• To elucidate the molecular mechanisms behind diet-induced clock remodeling.
• To determine if nutritional challenge or obesity drives these clock alterations.

Main Methods:

• Analysis of metabolic pathways and transcriptomic data in response to HFD.
• Investigation of CLOCK:BMAL1 chromatin recruitment.
• Assessment of the role of PPARγ in diet-induced clock changes.
• Distinguishing effects of nutritional challenge versus obesity.

Main Results:

• HFD causes significant reorganization of liver metabolic pathways and the liver clock.
• HFD induces de novo oscillating transcripts, disrupting coordinated oscillations.
• Impaired CLOCK:BMAL1 recruitment and cyclic PPARγ activation mediate reprogramming.
• Nutritional challenge, not obesity, is the primary driver of clock reprogramming.

Conclusions:

• Diet-induced reprogramming of the liver clock is substantial and involves specific molecular mechanisms.
• The liver clock's response is primarily to nutritional challenge, with effects being reversible.
• Understanding these dynamics is crucial for metabolic and circadian health.