Hawkins Liam J, Storey Kenneth B
Institute of Biochemistry and Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada.
J Comp Physiol B. 2018 Jan;188(1):113-125. doi: 10.1007/s00360-017-1112-7. Epub 2017 Jun 10.
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 < 0.05, n = 4). In skeletal muscle, H3K4me1 and H3K27me1 both decreased during freezing, whereas H3K9me3 and H3K36me2 were maintained across freezing and thaw (p < 0.05, n = 4). Methylation of p53 was also tissue-specific, where no changes were seen in liver tissue; however, p53 in skeletal muscle was differentially methylated. Overall, these results provide an evidence for the potential role methylation of histones and non-histone proteins play in freezing survival and entrance into a hypometabolic state.
耐冻动物通过多种转录、翻译和翻译后调控方法降低代谢率，从而在与冬季相关的零下温度和长期饥饿中存活下来。组蛋白甲基化是一种已知在转录水平调节基因表达的机制。在此，我们测量了耐冻林蛙（Rana sylvatica）在冻融循环期间骨骼肌和肝脏中七种组蛋白甲基转移酶（SMYD2、SETD7、ASH2L、RBBP5、SUV39H1、EHMT2和SET8）、四种甲基化组蛋白H3残基（H3K4me1、H3K9me3、H3K27me1和H3K36me2）的相对蛋白水平、H3K4上的甲基转移酶活性以及p53的甲基化（p53K370me2和p53K372me1）。总体而言，结果揭示了冻融过程中组蛋白甲基转移酶和组蛋白H3甲基化位点的组织特异性表达。在肝脏中，H3K4me1在冷冻期间显著降低，H3K9me3在所有条件下保持恒定，H3K27me1仅在解冻期间增加，H3K36me2在冷冻期间增加然后在解冻期间降低（p < 0.05，n = 4）。在骨骼肌中，H3K4me1和H3K27me1在冷冻期间均降低，而H3K9me3和H3K36me2在冻融过程中保持不变（p < 0.05，n = 4）。p53的甲基化也是组织特异性的，在肝脏组织中未观察到变化；然而，骨骼肌中的p53存在差异甲基化。总体而言，这些结果为组蛋白和非组蛋白蛋白质甲基化在冷冻存活和进入低代谢状态中所起的潜在作用提供了证据。
