Histone methylation in the freeze-tolerant wood frog (Rana sylvatica)

Freeze-tolerant animals survive sub-zero temperatures and long-term starvation associated with the winter by lowering their metabolic rate using a variety of transcriptional, translational, and post-translational regulatory methods. Histone methylation is one mechanism that is known to regulate gene expression at the transcriptional level. Here, we measured relative protein levels of seven histone methyltransferases (SMYD2, SETD7, ASH2L, RBBP5, SUV39H1, EHMT2, and SET8), four methylated histone H3 residues (H3K4me1, H3K9me3, H3K27me1, and H3K36me2), the methyltransferase activity on H3K4, and methylation of p53 (p53K370me2 and p53K372me1) in the skeletal muscle and liver of the freeze-tolerant wood frog (Rana sylvatica) during the freeze–thaw cycle. Overall, the results reveal a tissue-specific expression of histone methyltransferases and the methylation sites on histone H3 during freezing and thaw. In liver, H3K4me1 significantly decreased during freezing, H3K9me3 remained constant across conditions, H3K27me1 increased only during thaw, and H3K36me2 increased during freezing and then decreased during thaw (p