Circadian rhythms in skin and other elastic tissues

Adipocyte REVERBα dictates adipose tissue expansion during obesity

“…We identify extracellular matrix as a new direct target of adipose REVERBα action; altered regulation of WAT collagen production and modification is also likely to contribute to the rapid and continued adipose tissue expansion and reduced obesity-related fibrosis. The clock has been linked to ECM re-modelling in other tissues (Chang et al, 2020; Dudek et al, 2015; Sherratt et al, 2019), where it is thought to coordinate ECM dynamics, collagen turnover and secretory processes (Chang et al, 2020). Adipose-specific deletion of Reverbα now provides a unique model to explore the complex ECM responses which accompany obesity-related tissue hypertrophy and development of fibrosis.…”

Molecular Interactions between Pathogens and the Circadian Clock

“…Phenotypic studies of clock mutations have traditionally focused on general biology and physiology, and found a plethora of abnormalities that appear to belong to three main categories: Metabolic syndrome [45], aging, and immune dysregulation (Table 2 in reference [46]). Although much of this knowledge was derived from studies of knockout mice [46], the signaling routes connecting the central circadian clock to the peripheral clock [3,4,5] remained largely uncharted. The metabolic syndrome, referred to above, can indeed result from desynchronization between the central and peripheral clocks, for example through altered timing of food intake and diet composition [47].…”

“…Although circadian studies of these infections are lacking, such studies are warranted because a relationship can be anticipated for a multitude of reasons. First, many of the affected sites implicated above are part of the CC network, with their own tissue-specific clock gene expression profile and peripheral clocks [3,4]. The ability of E. coli and Klebsiella pneumonia to escape the gut microbiome (see below) should be affected by alteration of innate immunity during the day and night cycle, and also by sleep disturbances that are common in the elderly, the sick, and the caregivers working in night shifts, who are also exposed to nosocomial infections.…”

“…Feedback loops (TTFLs) of the mammalian circadian clock. This is a simplified snapshot of the highly complex circadian clock (CC) [2,3,4,5,6,7,8,9], depicting only the core pathways and the central players in transcriptional control. Most of the translational steps, including translation regulation by BMAL1 [10,11], are not shown for simplicity, but some are mentioned in the text of Section 2.…”

“…Although this review is focused mainly on the central clock, it should be noted that electrical and endocrine signals from the central clock, which originate in the SCN, signal to and orchestrate another ‘clock’ set, known as the “peripheral clock” [3,4]. Present in the other regions of the brain and in the tissues of the body, the peripheral clocks are partly independent, as they are entrained in the individual tissues.…”