Epigenetic transcriptional memory.

Organisms alter gene expression to adapt to changes in environmental conditions such as temperature, nutrients, inflammatory signals, and stress (Gialitakis et al. in Mol Cell Biol 30:2046-2056, 2010; Conrath in Trends Plant Sci 16:524-531, 2011; Avramova in Plant J 83:149-159, 2015; Solé et al. in Curr Genet 61:299-308, 2015; Ho and Gasch in Curr Genet 61:503-511, 2015; Bevington et al. in EMBO J 35:515-535, 2016; Hilker et al. in Biol Rev Camb Philos Soc 91:1118-1133, 2016). In some cases, organisms can "remember" a previous environmental condition and adapt to that condition more rapidly in the future (Gems and Partridge 2008). Epigenetic transcriptional memory in response to a previous stimulus can produce heritable changes in the response of an organism to the same stimulus, quantitatively or qualitatively altering changes in gene expression (Brickner et al. in PLoS Biol, 5:e81, 2007; Light et al. in Mol Cell 40:112-125, 2010; in PLoS Biol, 11:e1001524, 2013; D'Urso and Brickner in Trends Genet 30:230-236, 2014; Avramova in Plant J 83:149-159, 2015; D'Urso et al. in Elife. doi: 10.7554/eLife.16691 , 2016). The role of chromatin changes in controlling binding of poised RNAPII during memory is conserved from yeast to humans. Here, we discuss epigenetic transcriptional memory in different systems and our current understanding of its molecular basis. Our recent work with a well-characterized model for transcriptional memory demonstrated that memory is initiated by binding of a transcription factor, leading to essential changes in chromatin structure and allowing binding of a poised form of RNA polymerase II to promote the rate of future reactivation (D'Urso et al. in Elife. doi: 10.7554/eLife.16691 , 2016).