Department of Physiology, Medical College of Wisconsin, Milwaukee, Wis, USA.
Hypertension. 2010 Apr;55(4):974-82. doi: 10.1161/HYPERTENSIONAHA.109.144428. Epub 2010 Mar 1.
MicroRNAs are endogenous repressors of gene expression. We examined microRNAs in the renal medulla of Dahl salt-sensitive rats and consomic SS-13(BN) rats. Salt-induced hypertension and renal injury in Dahl salt-sensitive rats, particularly medullary interstitial fibrosis, have been shown previously to be substantially attenuated in SS-13(BN) rats. Of 377 microRNAs examined, 5 were found to be differentially expressed between Dahl salt-sensitive rats and consomic SS-13(BN) rats receiving a high-salt diet. Real-time PCR analysis demonstrated that high-salt diets induced substantial upregulation of miR-29b in the renal medulla of SS-13(BN) rats but not in SS rats. miR-29b was predicted to regulate 20 collagen genes, matrix metalloproteinase 2 (Mmp2), integrin beta1 (Itgb1), and other genes related to the extracellular matrix. Expression of 9 collagen genes and Mmp2 was upregulated by a high-salt diet in the renal medulla of SS rats, but not in SS-13(BN) rats, an expression pattern opposite to miR-29b. Knockdown of miR-29b in the kidneys of SS-13(BN) rats resulted in upregulation of several collagen genes. miR-29b reduced expression levels of several collagen genes and Itgb1 in cultured rat renal medullary epithelial cells. Moreover, miR-29b suppressed the activity of luciferase when the reporter gene was linked to a 3'-untranslated segment of collagen genes Col1a1, Col3a1, Col4a1, Col5a1, Col5a2, Col5a3, Col7a1, Col8a1, Mmp2, or Itgb1 but not Col12a1. The result demonstrated broad effects of miR-29b on a large number of collagens and genes related to the extracellular matrix and suggested involvement of miR-29b in the protection from renal medullary injury in SS-13(BN) rats.
microRNAs 是基因表达的内源性抑制剂。我们研究了 Dahl 盐敏感大鼠和 consomic SS-13(BN)大鼠肾髓质中的 microRNAs。先前的研究表明，Dahl 盐敏感大鼠的盐诱导性高血压和肾脏损伤，特别是髓质间质纤维化，在 SS-13(BN)大鼠中得到了显著减轻。在 377 个 microRNAs 中，有 5 个在接受高盐饮食的 Dahl 盐敏感大鼠和 consomic SS-13(BN)大鼠之间存在差异表达。实时 PCR 分析表明，高盐饮食诱导 SS-13(BN)大鼠肾髓质中 miR-29b 的大量上调，但在 SS 大鼠中没有。miR-29b 被预测调控 20 个胶原基因、基质金属蛋白酶 2 (Mmp2)、整合素 beta1 (Itgb1) 和其他与细胞外基质相关的基因。在 SS 大鼠的肾髓质中，高盐饮食上调了 9 个胶原基因和 Mmp2 的表达，但在 SS-13(BN)大鼠中没有，这与 miR-29b 的表达模式相反。在 SS-13(BN)大鼠的肾脏中敲低 miR-29b 导致几个胶原基因的上调。miR-29b 降低了培养的大鼠肾髓质上皮细胞中几个胶原基因和 Itgb1 的表达水平。此外，当报告基因与胶原基因 Col1a1、Col3a1、Col4a1、Col5a1、Col5a2、Col5a3、Col7a1、Col8a1、Mmp2 或 Itgb1 的 3'非翻译片段连接时，miR-29b 抑制了荧光素酶的活性，但不抑制 Col12a1。结果表明，miR-29b 对大量胶原基因和与细胞外基质相关的基因具有广泛的影响，并提示 miR-29b 参与了 SS-13(BN)大鼠肾髓质损伤的保护。
