bims-ciryme 2020-03-15 papers

Issue of 2020‒03‒15
two papers selected by
Gabriela Da Silva Xavier
University of Birmingham

Aging Cell. 2020 Mar 11. e13138

Reduced caloric intake and periodic fasting independently contribute to metabolic effects of caloric restriction.

Nikkhil Velingkaar, Volha Mezhnina, Allan Poe, Kuldeep Makwana, Richa Tulsian, Roman V Kondratov.

Caloric restriction (CR) has positive effects on health and longevity. CR in mammals implements time-restricted (TR) feeding, a short period of feeding followed by prolonged fasting. Periodic fasting, in the form of TR or mealtime, improves metabolism without reduction in caloric intake. In order to understand the relative contribution of reduced food intake and periodic fasting to the health benefits of CR, we compared physiological and metabolic changes induced by CR and TR (without reduced food intake) in mice. CR significantly reduced blood glucose and insulin around the clock, improved glucose tolerance, and increased insulin sensitivity (IS). TR reduced blood insulin and increased insulin sensitivity, but in contrast to CR, TR did not improve glucose homeostasis. Liver expression of circadian clock genes was affected by both diets while the mRNA expression of glucose metabolism genes was significantly induced by CR, and not by TR, which is in agreement with the minor effect of TR on glucose metabolism. Thus, periodic fasting contributes to some metabolic benefits of CR, but TR is metabolically different from CR. This difference might contribute to differential effects of CR and TR on longevity.

Keywords: caloric restriction; circadian rhythms; fasting; gene expression; glucose homeostasis; insulin sensitivity; longevity; metabolism

DOI: https://doi.org/10.1111/acel.13138

Epigenomics. 2020 Mar 11.

Transcriptomic and epigenomics atlas of myotubes reveals insight into the circadian control of metabolism and development.

Ali Altıntaş, Rhianna C Laker, Christian Garde, Romain Barrès, Juleen R Zierath.

Aim: Innate circadian rhythms are critical for optimal tissue-specific functions, including skeletal muscle, a major insulin-sensitive tissue responsible for glucose homeostasis. We determined whether transcriptional oscillations are associated with CpG methylation changes in skeletal muscle. Materials & methods: We performed rhythmicity analysis on the transcriptome and CpG methylome of circadian synchronized myotubes. Results: We identified several transcripts and CpG-sites displaying oscillatory behavior, which were enriched with GO terms related to metabolism and development. Oscillating CpG methylation was associated with rhythmic expression of 31 transcripts. Conclusion: Although circadian oscillations may be regulated by rhythmic DNA methylation, strong rhythmic associations between transcriptome and CpG methylation were not identified. This resource constitutes a transcriptomic/epigenomic atlas of skeletal muscle and regulation of circadian rhythms.

Keywords: C2C12; circadian; epigenetics; methylation; muscle; myotube; transcriptomics

DOI: https://doi.org/10.2217/epi-2019-0391