Interactions between the circadian clock and metabolism: there are good times and bad times

Abstract

An endogenous circadian (∼24 h) clock regulates rhythmic processes of physiology, metabolism and behavior in most living organisms. While able to free-run under constant conditions, the circadian clock is coupled to day : night cycles to increase its amplitude and align the phase of circadian rhythms to the right time of the day. Disruptions of the circadian clock are correlated with brain dysfunctions, cardiovascular diseases and metabolic disorders. In this review, we focus on the interactions between the circadian clock and metabolism. We discuss recent findings on circadian clock regulation of feeding behavior and rhythmic expression of metabolic genes, and present evidence of metabolic input to the circadian clock. We emphasize how misalignment of circadian clocks within the body and with environmental cycles or daily schedules leads to the increasing prevalence of metabolic syndromes in modern society.

Transcriptome survey of phototransduction and clock genes in marine bivalves

“…The present results support the inference that the basic framework of clock regulation is highly conserved not only in terrestrial species, from insects to rodents and humans, but also in marine mollusks (Panda et al, 2002;Lowrey and Takahashi, 2000;Shi and Zheng, 2013), which suggests a convergent evolution of circadian timing mechanisms and raises the possibility that the underlying timekeeping mechanism may also be conserved.…”

“…In another feedback loop, Clock:Cycle activates the transcription of Vri and Pdp, and their proteins feedback to repress and activate Clock mRNA transcription, respectively (Golombek and Rosenstein, 2010). Shi and Zheng (2013). Dashed black lines indicate the hypothetical relationships based on expression data from the current study.…”

“…Most terrestrial organisms possess a circadian clock, which controls metabolic reactions and physiological processes according to daily light-dark cycles (Panda et al, 2002;Schrago, 2006;Golombek and Rosenstein, 2010;Shi and Zheng, 2013). In addition to the circadian rhythm, marine organisms also exhibit lunar-related rhythms that are regulated by lunar periodicity (Ikegami et al, 2014).…”

The small G protein RAS2 is involved in the metabolic compensation of the circadian clock in the circadian model Neurospora crassa

“…Among these adaptation mechanisms the most intensively investigated process is temperature compensation. Although a tight interaction between metabolism and the circadian clock has been shown at almost all levels of organisms (1)(2)(3), it is still poorly understood how molecular timekeeping is compensated against changes in nutrient availability. Neurospora crassa belongs to the most extensively examined model systems in the field of circadian research and has proved to serve as a useful tool for the investigation of different aspects of circadian regulation including metabolic compensation of the circadian clock (4).…”

The unfolded protein response, inflammation, oscillators, and disease: a systems biology approach

“…Another major development with practical applications from the information systems underlying such physiological and biochemical phenomena, is the realization that energy metabolism is tightly regulated by a web of biological oscillators distributed in peripheral tissues, and entrained by environmental changes that follow a circadian rhythm dictated by the SCN [10,[23][24][25] In this review we will attempt to use a systems biology approach to explore such interactions as a whole to get at least some partial answers to two fundamental questions regarding the role of ER stress on disease: [1] how dependent is the UPR and subsequent events referred above, to its state of synchrony with the SCN and peripheral oscillators? And, [2] How could modifiers of the activity of SCN, (for example, by means of changing food intake, exercise, and drugs) be used to modulate ER stress and systemic inflammation to ameliorate or even prevent NCDs?…”