Epigenetic control of gene expression in adult tissues is crucial to maintain organ function and homeostasis. A report in this issue of The EMBO Journal (Chiacchiera et al, 2016b), together with another one published in Gastroenterology (Koppens et al, 2016), unveils how chromatin repressive complex PRC2 controls the equilibrium between secretory and absorptive fates in the intestine. PRC2 controls proliferation of cells within the crypt and at the same time represses the transcription factor Atoh1, thus favoring the generation of enterocytes versus secretory cell types in the adult intestine.
See also: F Chiacchiera et al (November 2016)
Understanding the control of gene expression is one of the major challenges to understanding living organisms. In any given adult organism, nearly all somatic cells share an identical genomic sequence, which implies that different layers of control establish which set of genes are expressed in a given cell type, ultimately specifying cell function. To achieve this high level of control, epigenetics factors contribute to regulating gene expression by a plethora of mechanisms, such as covalent modifications of DNA and histone proteins. Further, it is critical that gene expression is regulated in a spatiotemporal fashion during both development and homeostasis. Epigenetic machineries are often multiprotein complexes that are able to introduce, read, or erase covalent modifications on chromatin, which in turn affect the transcription level of adjacent or associated genes. Two examples of …
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