Nutrient Levels May Signal Seasonal Changes by Modifying the PER2 Protein

A high fat diet (HFD) promotes entrainment to a summer light cycle while inhibiting entrainment to a winter light cycle.

• Nutrient content influences the alignment of circadian rhythms with seasonal changes in light.
• Phosphorylation of the PER2 protein on serine 662 is necessary for dietary regulation of seasonal circadian rhythms.
• Mice with a phospho-mimetic mutation of PER2-S662 could not adjust to winter light conditions.
• Mice with a phospho-null mutation of PER2-S662 could not adjust to summer light conditions, even with a high fat diet.
• Polyunsaturated fatty acids play a role in the nutrient-dependent regulation of seasonal circadian rhythms.

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