Pinto Rodrigo, Ivaldi Corinne, Reyes Mauricio, Doyen Cécile, Mietton Flore, Mongelard Fabien, Alvarez Marco, Molina Alfredo, Dimitrov Stefan, Krauskopf Manuel, Vera Maria Ines, Bouvet Philippe
Millennium Institute for Fundamental and Applied Biology and Biological Sciences Department, Universidad Andres Bello, Santiago, Chile.
FEBS Lett. 2005 Oct 24;579(25):5553-8. doi: 10.1016/j.febslet.2005.09.019. Epub 2005 Sep 28.
Adaptation to cold and warm conditions requires dramatic change in gene expression. The acclimatization process of the common carp Cyprinus carpio L. in its natural habitat has been used to study how organisms respond to natural environmental changes. At the cellular level, adaptation to cold condition is accompanied by a dramatic alteration in nucleolar structure and a down regulation of the expression of ribosomal genes. We show that the enrichment of condensed chromatin in winter adapted cells is not correlated with an increase of the heterochromatin marker trimethyl and monomethyl K20H4. However, the expression of the tri methyl K4 H3 and of the variant histone macroH2A is significantly increased during the winter season together with a hypermethylation of CpG residues. Taking into account the properties of macroH2A toward chromatin structure and dynamics and its role in gene repression our data suggest that the increased expression of macroH2A and the hypermethylation of DNA which occurs upon winter-acclimatization plays a major role for the reorganization of chromatin structure and the regulation of gene expression during the physiological adaptation to a colder environment.
适应寒冷和温暖条件需要基因表达发生显著变化。鲤鱼（Cyprinus carpio L.）在其自然栖息地的驯化过程已被用于研究生物体如何应对自然环境变化。在细胞水平上，适应寒冷条件伴随着核仁结构的显著改变以及核糖体基因表达的下调。我们发现，冬季适应细胞中浓缩染色质的富集与异染色质标记三甲基和一甲基K20H4的增加无关。然而，在冬季，三甲基K4 H3和变体组蛋白macroH2A的表达显著增加，同时CpG残基发生超甲基化。考虑到macroH2A对染色质结构和动力学的特性及其在基因抑制中的作用，我们的数据表明，冬季驯化时macroH2A表达的增加和DNA的超甲基化在生理适应较冷环境过程中对染色质结构的重组和基因表达的调控起主要作用。
