Sinha Puja, Singh Kiran, Sachan Manisha
Department of Biotechnology, Motilal Nehru National Institute of Technology, Allahabad, 211004 India.
Department of Molecular and Human Genetics, Banaras Hindu University, Varanasi, India.
Gene Expr Patterns. 2017 Jan;23-24:59-69. doi: 10.1016/j.gep.2017.03.004. Epub 2017 Mar 28.
Homeobox genes encode a group of DNA binding regulatory proteins whose key function occurs in the spatial-temporal organization of genome during embryonic development and differentiation. The role of these Hox genes during ontogenesis makes it an important model for research. HoxA5 is a member of Hox gene family playing a central role during axial body patterning and morphogenesis. DNA modification studies have shown that the function of Hox genes is partly governed by the methylation-mediated gene expression regulation. Therefore the study aimed to investigate the role of epigenetic events in regulation of tissue-specific expression pattern of HoxA5 gene during mammalian development. The methodology adopted were sodium bisulfite genomic DNA sequencing, quantitative real-time PCR and chromatin-immunoprecipitation (ChIP). Methylation profiling of HoxA5 gene promoter shows higher methylation in adult as compared to fetus in various somatic tissues of mouse being highest in adult spleen. However q-PCR results show higher expression during fetal stages being highest in fetal intestine followed by brain, liver and spleen. These results clearly indicate a strict correlation between DNA methylation and tissue-specific gene expression. The findings of chromatin-immunoprecipitation (ChIP) have also reinforced that epigenetic event like DNA methylation plays important role in the regulation of tissue specific expression of HoxA5.
同源框基因编码一类DNA结合调节蛋白，其关键功能发生在胚胎发育和分化过程中基因组的时空组织中。这些Hox基因在个体发生过程中的作用使其成为一个重要的研究模型。HoxA5是Hox基因家族的成员，在轴体模式形成和形态发生过程中起核心作用。DNA修饰研究表明，Hox基因的功能部分受甲基化介导的基因表达调控。因此，本研究旨在探讨表观遗传事件在哺乳动物发育过程中对HoxA5基因组织特异性表达模式调控中的作用。采用的方法有亚硫酸氢盐基因组DNA测序、定量实时PCR和染色质免疫沉淀（ChIP）。HoxA5基因启动子的甲基化分析显示，与胎儿相比，成年小鼠各种体细胞组织中的甲基化水平更高，成年脾脏中最高。然而，q-PCR结果显示，胎儿期表达较高，胎儿肠道中最高，其次是脑、肝和脾。这些结果清楚地表明DNA甲基化与组织特异性基因表达之间存在严格的相关性。染色质免疫沉淀（ChIP）的结果也进一步证明，像DNA甲基化这样的表观遗传事件在HoxA5组织特异性表达的调控中起重要作用。
