MicroRNA-192 in diabetic kidney glomeruli and its function in TGF-β-induced collagen expression via inhibition of E-box repressors
MicroRNA-192 in diabetic kidney glomeruli and its function in TGF-β-induced collagen expression via inhibition of E-box repressors
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DOI：
10.1073/pnas.0611192104
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发表时间：
2007-02-27
影响因子：
11.1
通讯作者：
Natarajan, Rama
中科院分区：
文献类型：
--
作者：
Kato, Mitsuo;Zhang, Jane;Natarajan, Rama
糖尿病肾病的主要特征包括细胞外基质蛋白的积聚，如胶原1-α1和-2(Col1a1和-2)。转化生长因子β1是这些细胞外基质基因的关键调节因子，在糖尿病肾病肾小球系膜细胞(MC)中表达增加。通过基因芯片分析，我们注意到，转化生长因子-β增加了小鼠MC(MMC)中Col1a2的mRNA水平，但也降低了E-box抑制因子Delta EF1的mRNA水平。转化生长因子-β处理或针对Delta EF1的短发夹状RNA增加了Col1a2基因上游E-box元件的增强子活性。转化生长因子-β也降低了Smad相互作用蛋白1(SIP1)的表达，SIP1是另一种类似于Delta EF1的E盒抑制物。有趣的是，我们注意到SIN是microRNA-192(miR-192)的靶标，microRNA-192(miR-192)是一种在肾脏高表达的关键miR。MMC经转化生长因子-β处理后，MIR-192水平也明显升高。经转化生长因子-β处理或miR-192转染后，MMC内源性SIP1的表达及含SIP1 3‘UTIR荧光素酶的报告活性均降低。相反，miR-192抑制剂增强了荧光素酶的活性，确认SIP1是miR-192的靶标。此外，miR-192与Delta EF1短发夹RNA协同作用，增加了Col1a2 E-box-Luc的活性。重要的是，观察到从注射链脲佐菌素的糖尿病小鼠和糖尿病db/db小鼠分离的肾小球中miR-192水平显著高于相应的非糖尿病对照组，同时伴随着转化生长因子-β和Col1a2水平的增加，这一体内相关性被注意到。这些结果揭示了肾脏和肾脏中的miRs通过下调E-box抑制物来控制转化生长因子-β诱导的Col1a2表达的作用。
Key features of diabetic nephropathy (DN) include the accumulation of extracellular matrix proteins such as collagen 1-alpha 1 and -2 (Col1a1 and -2). Transforming growth factor beta 1 (TGF-beta), a key regulator of these extracellular matrix genes, is increased in mesangial cells (MC) in DN. By microarray profiling, we noted that TGF-beta increased Col1a2 mRNA in mouse MC (MMC) but also decreased mRNA levels of an E-box repressor, delta EF1. TGF-beta treatment or short hairpin RNAs targeting delta EF1 increased enhancer activity of upstream E-box elements in the Col1a2 gene. TGF-beta also decreased the expression of Smad-interacting protein 1 (SIP1), another E-box repressor similar to delta EF1. Interestingly, we noted that SIN is a target of microRNA-192 (miR-192), a key miR highly expressed in the kidney. miR-192 levels also were increased by TGF-beta in MMC. TGF-beta treatment or transfection with miR-192 decreased endogenous SIP1 expression as well as reporter activity of a SIP1 3' UTIR-containing luciferase construct in MMC. Conversely, a miR-192 inhibitor enhanced the luciferase activity, confirming SIP1 to be a miR-192 target. Furthermore, miR-192 synergized with delta EF1 short hairpin RNAs to increase Col1a2 E-box-luc activity. Importantly, the in vivo relevance was noted by the observation that miR-192 levels were enhanced significantly in glomeruli isolated from streptozotocin-injected diabetic mice as well as diabetic db/db mice relative to corresponding nondiabetic controls, in parallel with increased TGF-beta and Col1a2 levels. These results uncover a role for miRs in the kidney and DN in controlling TGF-beta-induced Col1a2 expression by down-regulating E-box repressors.