Genome-Wide Identification and Characterization of Main Histone Modifications in Sorghum Decipher Regulatory Mechanisms Involved by mRNA and Long Noncoding RNA Genes

Post-translational modifications
of histones play an important
chromatic role of a transcript activity in eukaryotes. Even though
mRNA and long noncoding RNA (lncRNA) genes share similar biogenetic
processes, these transcript classes may differ in many ways. However,
knowledge about the crosstalk between histone methylations and the
two types of sorghum genes is still ambiguous. In the present study,
we reveal the genome-wide distribution of six histone modifications,
namely, di- and trimethylation of H3K4 (H3K4me2 and H3K4me3), H3K27
(H3K27me2 and H3K27me3), and H3K36 (H3K36me2 and H3K36me3) in sorghum
and analyze their functional relationships. Unlike other histone methylation,
the codecoration of H3K4me3 and H3K36me3 is negatively associated
with the production of lincRNAs in the context of active expression
of mRNA genes. Our data demonstrated that H3K4me3 may act as a complementary
component to H3K36me3 in the transcriptional regulatory process. Moreover,
we observe that both H3K4me3 and H3K36me3 are involved in the negative-going
regulation of plant lincRNA and mRNA genes. Our data provide a genome-wide
landscape of histone methylation in sorghum, decrypt its reciprocity,
and shed light on its transcriptional regulation roles in mRNA and
lncRNA genes.

组蛋白的翻译后修饰在真核生物的转录调控过程中发挥关键的染色质功能。尽管信使RNA（mRNA）与长链非编码RNA（long noncoding RNA，lncRNA）基因拥有相似的生物发生过程，但这两类转录本在诸多方面存在差异。然而，目前关于组蛋白甲基化与高粱两类基因之间的交叉调控关系的认知仍较为模糊。本研究绘制了高粱基因组范围内6种组蛋白修饰的全分布图谱，具体包括H3K4的二甲基化与三甲基化（H3K4me2、H3K4me3）、H3K27的二甲基化与三甲基化（H3K27me2、H3K27me3）以及H3K36的二甲基化与三甲基化（H3K36me2、H3K36me3），并分析了这些修饰的功能关联。与其他组蛋白甲基化修饰不同，在mRNA基因活跃表达的背景下，H3K4me3与H3K36me3的共修饰与基因间长链非编码RNA（long intergenic noncoding RNA，lincRNA）的生成呈负相关。本研究数据表明，在转录调控过程中，H3K4me3可作为H3K36me3的互补调控因子。此外，本研究发现H3K4me3与H3K36me3均参与植物基因间长链非编码RNA及mRNA基因的负向调控。本研究数据构建了高粱组蛋白甲基化的全基因组图谱，解析了其相互调控关系，并阐明了其在mRNA与lncRNA基因转录调控中的功能。