Promoter methylation is associated with the age-dependent loss of N-cadherin in the rat kidney
Promoter methylation is associated with the age-dependent loss of N-cadherin in the rat kidney
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DOI：
10.1152/ajprenal.00285.2007
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发表时间：
2008-01-01
影响因子：
4.2
通讯作者：
Parrish, Alan R.
中科院分区：
文献类型：
--
作者：
Akintola, Adebayo D.;Crislip, Zachary L.;Parrish, Alan R.
钙粘蛋白是维持细胞稳态所需的细胞粘附分子，N-钙粘蛋白是人类和大鼠近端肾小管上皮细胞中表达的主要钙粘蛋白。我们的实验室先前报道了肾脏N-钙粘蛋白表达的年龄依赖性降低; N-钙粘蛋白mRNA和蛋白表达水平平行降低，暗示了年龄依赖性表达丧失的转录机制（19）。在这项研究中，我们研究了这一假设，即启动子甲基化的基础上的N-钙粘蛋白表达的损失在老龄大鼠肾脏。我们克隆了大鼠N-cadherin基因的5'侧翼区，并在紧邻ATG起始位点上游的3，992-bp区域观察到基本的启动子活性。核苷酸分析显示与人N-钙粘蛋白最小启动子区87%的同一性。与DNA甲基化调控的作用一致，我们发现大鼠N-钙粘蛋白基因侧翼有一个密集的CpG岛，跨度为1,104 bp（-1,158至-55）;在人类N-钙粘蛋白5'侧翼区域也发现了类似的CpG分布。甲基化特异性PCR分析表明，N-钙粘蛋白的启动子区域是严重甲基化的老年，但不是年轻的，大鼠肾脏。有趣的是，启动子在年龄匹配的、热量限制的动物中没有甲基化。相比之下，启动子区域是不甲基化的年轻或老年大鼠肝脏，这对应于发现，衰老是不相关的N-钙粘蛋白表达减少在肝脏中。此外，在用DNA甲基转移酶抑制剂5-氮杂-2 '-脱氧胞苷处理的NRK-52 E细胞中，N-钙粘蛋白表达被显著诱导，进一步表明启动子区域中CpG的甲基化可能是肾N-钙粘蛋白表达的年龄依赖性降低的基础。
The cadherins are cell adhesion molecules required for cellular homeostasis, and N-cadherin is the predominant cadherin expressed in proximal tubular epithelial cells in humans and rats. Our laboratory previously reported an age-dependent decrease in renal N-cadherin expression; the levels of N-cadherin mRNA and protein expression decreased in parallel, implicating a transcriptional mechanism in the age-dependent loss of expression (19). In this study, we examined the hypothesis that promoter hypermethylation underlies the loss of N-cadherin expression in aging rat kidney. We cloned the 5' flanking region of the rat N-cadherin gene and observed basic promoter activity in a 3,992-bp region localized immediately upstream of the ATG start site. Nucleotide analysis revealed 87% identity with the human N-cadherin minimal promoter region. Consistent with a role for regulation by DNA methylation, we found that a dense CpG island, which spans 1,104 bp (-1,158 to -55), flanks the rat N-cadherin gene; a similar CpG profile was found in the human N-cadherin 5' flanking region. Methylation-specific PCR analysis demonstrated that the promoter region of N-cadherin is heavily methylated in aged, but not young, rat kidney. Interestingly, the promoter is not methylated in age-matched, calorically restricted animals. In contrast, the promoter region is not methylated in either young or aged rat liver; this corresponds to the finding that aging is not associated with decreased N-cadherin expression in the liver. In addition, N-cadherin expression is markedly induced in NRK-52E cells treated with the DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine, further suggesting that methylation at CpG in the promoter region may underlie the age-dependent decrease in renal N- cadherin expression.