Circadian Clocks: From Stem Cells to Tissue Homeostasis and Regeneration

The document from 2017 reviews the significance of circadian clocks in stem cells and their role in tissue homeostasis and regeneration. It explains that circadian rhythms, which follow roughly 24-hour cycles, are essential for various physiological functions and are regulated by a molecular clock machinery involving core transcription factors like BMAL1 and CLOCK. These factors control the expression of clock-controlled genes (CCGs) in a tissue-specific manner. Disruptions in circadian rhythms are associated with several diseases and can impair regenerative capacities. The review details how circadian rhythms are absent in embryonic stem cells but emerge upon differentiation, with human embryonic stem cells acquiring a functional clock when differentiated towards cardiac cells. Adult stem cells, unlike embryonic ones, have a functional circadian clock that aids in tissue repair and regeneration. The document also notes that circadian gene expression changes with age and can be influenced by factors like caloric restriction. It suggests that understanding these rhythms in stem cells could lead to better therapies for aging and regeneration, with synthetic ligands targeting clock components being considered for therapeutic use. Specific numbers of study participants are not provided in the summary.