Site-specific DNA hypomethylation permits expression of the IRBP gene
Site-specific DNA hypomethylation permits expression of the IRBP gene
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DOI：
10.1016/s0006-8993(00)02990-5
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发表时间：
2000-12-22
期刊：
影响因子：
2.9
通讯作者：
Borst, DE
中科院分区：
文献类型：
--
作者：
Boatright, JH;Nickerson, JM;Borst, DE
视黄醇受体间结合蛋白(IRBP)是视觉周期的重要组成部分，在视网膜和松果体中选择性表达。这项研究考察了位点特异性DNA低甲基化是否在这种表达调控中发挥作用。对牛和小鼠不同组织(全脑、视网膜、松果体、上丘、皮质、胸腺、缰核、角膜、肝脏、尾巴和肾脏)DNA的HpaII和MspI酶切的Southern blotting表明，与来自其他组织的DNA相比，IRBP基因启动子中特定的CpG二核苷酸在视网膜感光细胞和松果体的DNA中发生了低甲基化。这些位点在非感光视网膜细胞的DNA中甲基化。在电泳迁移率改变分析中，这些位点的外源甲基化减少了DNA：蛋白质的结合。氯霉素乙酰转移酶报告基因HpaII甲基化构建了瞬时转染鸡视网膜细胞原代培养中抑制IRBP而不是SV40启动子活性的结构。这些数据表明，牛和小鼠IRBP启动子中的特定胞嘧啶在感光细胞中未甲基化，但在其他组织中甲基化。这种差异DNA甲基化可能调节IRBP基因的表达，因为小鼠位点的外源性甲基化抑制了报告基因的转录，显然是通过抑制DNA：蛋白质结合事件。(C)2000年爱思唯尔科学公司。版权所有。
Interphotoreceptor retinoid binding protein (IRBP), a putative component of the visual cycle, is expressed selectively in the retina and pineal gland. This study examined whether site-specific DNA hypomethylation plays a role in this expression regulation. Southern blotting of HpaII and MspI digests of DNA from various bovine and murine tissues (whole brain, retina, pineal gland, superior colliculus, cortex, thymus, habenular nucleus, cornea, liver, tail, and kidney) revealed that specific CpG dinucleotides in the IRBP gene promoter are hypomethylated in DNA from retinal photoreceptor cells and pineal gland compared to DNA from other tissues. These sites are methylated in DNA from non-photoreceptor retinal cells. Exogenous methylation of these sites diminished DNA:protein binding in electrophoretic mobility shift assays. HpaII methylation of chloramphenicol acetyltransferase reporter constructs suppressed IRBP but not SV40 promoter activity in transiently transfected primary cultures of embryonic chick retinal cells. These data indicate that specific cytosines in the bovine and murine IRBP promoters are unmethylated in photoreceptive cells but methylated in other tissues. This differential DNA methylation may modulate IRBP gene expression since exogenous methylation of the murine sites suppresses reporter gene transcription, apparently by inhibiting DNA:protein binding events. (C) 2000 Elsevier Science BN. All rights reserved.