The regulation of [m.sup.6]A-related proteins during whole-body freezing of the freeze-tolerant wood frog

Rana sylvatica (also known as Boreorana sylvatica) is one of the few vertebrates that spend extreme winters showing no physiological signs of life. Up to 70% of the total body water of the wood frog freezes as extracellular ice. Survival in extreme conditions requires regulation at transcriptional and translational levels to activate prosurvival pathways. N6-methyladenosine ([m.sup.6]A) methylation is one of the most common RNA modifications, regulating transcript processing and translation by executing important functions that affect regulatory pathways in stress conditions. In the study, regulation of [m.sup.6]A-related proteins in the liver of R. sylvatica was analyzed during 24 h frozen and 8 h thaw conditions. Decreases in the activity of demethylases of 28.44 [+ or -] 0.4% and 24.1 [+ or -] 0.9% of control values in frozen and thaw tissues, respectively, were observed. Total protein levels of [m.sup.6]A methyltransferase complex components methyltransferase-like 14 and Wilm's tumor associated protein were increased by 1.28-fold and 1.42-fold, respectively, during freezing. Demethylase fat mass and obesity, however, showed a decreasing trend, with a significant decrease in abundance during recovery from frozen conditions. Levels of mRNA degraders YTHDF2 and YTHDC2 also decreased under stress. Overall, increased levels of [m.sup.6]A methylation complex components, and suppressed levels of readers/erasers, provide evidence for the potential role of RNA methylation in freezing survival and its regulation in a hypometabolic state. Key words: epigenetics, freeze tolerance, RNA methylation, metabolic rate depression, Rana sylvatica (Boreorana sylvatica)
Introduction The wood frog, Rana sylvatica (Boreorana sylvatica), is one of the freeze-tolerant model organisms that survive sub-zero temperatures for several months. During freezing, the wood frog employs multiple adaptation [...]