Dynamic changes in global and gene specific DNA methylation during hibernation in adult thirteen-lined ground squirrels,Ictidomys tridecemlineatus

Abstract

Hibernating mammals conserve energy in the winter by undergoing prolonged bouts of torpor, interspersed with brief arousals back to euthermia. These bouts are accompanied by a suite of reversible physiological and biochemical changes; however, much remains to be discovered about the molecular mechanisms involved. Given the seasonal nature of hibernation, it stands to reason that underlying plastic epigenetic mechanisms should exist. One such form of epigenomic regulation involves the reversible modification of cytosine bases in DNA by methylation. DNA methylation is well known to be a mechanism that confers upon DNA its cellular identity during differentiation in response to innate developmental cues. However, it has recently been hypothesized that DNA methylation also acts as a mechanism for adapting genome function to changing external environmental and experiential signals over different time scales, including during adulthood. Here, we tested the hypothesis that DNA methylation is altered during hibernation in adult wild animals. This study evaluated global changes in DNA methylation in response to hibernation in the liver and skeletal muscle of thirteen-lined ground squirrels along with changes in expression of DNA methyltransferases (DNMT1/3B) and methyl binding domain proteins (MBDs). A reduction in global DNA methylation occurred in muscle during torpor phases whereas significant changes in DNMTs and MBDs were seen in both tissues. We also report dynamic changes in DNA methylation in the promoter of the myocyte enhancer factor 2C (mef2c) gene, a candidate regulator of metabolism in skeletal muscle. Taken together, these data show that genomic DNA methylation is dynamic across torporarousal bouts during winter hibernation, consistent with a role for this regulatory mechanism in contributing to the hibernation phenotype.

Waking the sleeping dragon: gene expression profiling reveals adaptive strategies of the hibernating reptile Pogona vitticeps

“…Increased expression of components of the Sin3A-HDAC complex is common to bearded dragons ( Fig. 2a), hibernating squirrels and frogs [46][47][48][49] (Fig. 5).…”

Avian ecological epigenetics: pitfalls and promises

“…Seasonal events require an individual to undergo a combination of morphological, physiological and behavioural changes and hence the seasonal regulation of gene expression in various tissues (Stevenson 2018;Wingfield 2005). Recent studies in species of plants (Lai et al 2018;Law and Jacobsen 2010;Shi et al 2015;Wilschut et al 2016), insects (Hatakeyama and Mueller 2008;Pegoraro et al 2016), and rodents (Alvarado et al 2015;Lynch et al 2017;Stevenson and Prendergast 2013) show evidence for reversible epigenetic modifications, especially DNA methylation, to be involved in this. How reversible DNA methylation can shape seasonally stimulated life history events in an animal species is best studied and understood in the Siberian Hamster (Phodopus sungorus), in which short day length inhibits hypothalamic DNA methyltransferase 3a (DNMT3a) expression causing reduced promoter methylation in type III deiodinase, a gene involved in the photoperiodic regulation of reproduction (Lynch et al 2016;Stevenson 2017;Stevenson and Prendergast 2013).…”

Diurnal and seasonal molecular rhythms in human neocortex and their relation to Alzheimer’s disease

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