Increased Glomerular and Tubular Expression of Transforming Growth Factor-β1, Its Type II Receptor, and Activation of the Smad Signaling Pathway in the db/db Mouse
Increased Glomerular and Tubular Expression of Transforming Growth Factor-β1, Its Type II Receptor, and Activation of the Smad Signaling Pathway in the db/db Mouse
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DOI：
10.1016/s0002-9440(10)64121-1
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发表时间：
2001-05
影响因子：
6
通讯作者：
Soon Won Hong;M. Isono;Sheldon Chen;M. C. Iglesias-de la Cruz;D. Han;F. Ziyadeh
中科院分区：
文献类型：
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作者：
Soon Won Hong;M. Isono;Sheldon Chen;M. C. Iglesias-de la Cruz;D. Han;F. Ziyadeh
肾转化生长因子-β (TGF-β)系统的激活可能介导了糖尿病肾脏细胞外基质的过量产生。为了确定TGF-β系统在2型糖尿病肾病中的作用，我们在16周龄的db/db小鼠中检测了TGF-β1异构体、TGF-β II型受体和Smad信号通路的肾内定位和表达。db/db是2型糖尿病的遗传模型，表现出与人类疾病相似的系膜基质扩张、肾小球基底膜增厚和肾功能不全。原位杂交结果显示，与非糖尿病小鼠相比，db/db小鼠肾小球和肾小管间室TGF-β1 mRNA表达显著升高。同样，免疫组化染色显示TGF-β1蛋白在两肾间室中均升高，但TGF-β1蛋白在肾小球中的部分表达量低于mRNA。TGF-β II型受体的原位杂交和免疫组化染色显示，糖尿病动物肾小球和肾小管间室中mRNA和蛋白的表达一致且显著升高。最后，免疫组织化学显示Smad3在糖尿病患者肾小球和小管细胞的细胞核中优先积累。使用标记的smad结合元件的西南组织化学补充技术显示核蛋白与smad结合元件的结合增加，表明TGF-β刺激的下游有活性信号传导。因此，我们提出在2型糖尿病动物模型中，TGF-β系统在整个肾皮质的配体、受体和信号水平上调。我们的研究结果表明，TGF-β的促纤维化作用可能是糖尿病肾病的肾小球硬化和小管间质纤维化进展的基础。
Activation of the renal transforming growth factor-β (TGF-β) system likely mediates the excess production of extracellular matrix in the diabetic kidney. To establish the role of the TGF-β system in type 2 diabetic nephropathy, we examined the intrarenal localization and expression of the TGF-β1 isoform, the TGF-β type II receptor, and the Smad signaling pathway in the 16-week-old db/db mouse, a genetic model of type 2 diabetes that exhibits mesangial matrix expansion, glomerular basement membrane thickening, and renal insufficiency that closely resemble the human disease. Compared with its nondiabetic db/m littermate, the db/db mouse showed significantly increased TGF-β1 mRNA expression by in situ hybridization in both glomerular and tubular compartments. Likewise, TGF-β1 protein, by immunohistochemical staining, was increased in both renal compartments, but the fractional expression of TGF-β1 protein was less than that of the mRNA in the glomerulus. In situ hybridization and immunohistochemical staining for the TGF-β type II receptor revealed concordant and significant increases of both mRNA and protein in the glomerular and tubular compartments of diabetic animals. Finally, immunohistochemistry showed preferential accumulation of Smad3 in the nuclei of glomerular and tubular cells in diabetes. The complementary technique of Southwestern histochemistry using a labeled Smad-binding element demonstrated increased binding of nuclear proteins to Smad-binding element, indicating active signaling downstream of the TGF-β stimulus. We therefore propose that the TGF-β system is up-regulated at the ligand, receptor, and signaling levels throughout the renal cortex in this animal model of type 2 diabetes. Our findings suggest that the profibrotic effects of TGF-β may underlie the progression to glomerulosclerosis and tubulointerstitial fibrosis that characterize diabetic nephropathy.