Regulation of connective tissue growth factor activity in cultured rat mesangial cells and its expression in experimental diabetic glomerulosclerosis
Regulation of connective tissue growth factor activity in cultured rat mesangial cells and its expression in experimental diabetic glomerulosclerosis
复制标题
DOI：
10.1681/asn.v11125
复制
发表时间：
2000-01-01
影响因子：
13.6
通讯作者：
Narins, RG
中科院分区：
文献类型：
--
作者：
Riser, BL;Denichilo, M;Narins, RG
结缔组织生长因子 (CTGF) 是一种由培养的内皮细胞和成纤维细胞在受到转化生长因子-β (TGF-β) 刺激时分泌的肽，在冠状动脉和皮肤的纤维化过程中过度表达。为了确定 CTGF 是否与糖尿病肾小球硬化的发病机制有关，我们对肥胖、糖尿病 db/db 小鼠及其正常小鼠的培养的大鼠系膜细胞 (MC) 以及肾皮质和显微解剖肾小球进行了检查。将 MC 暴露于重组人 CTGF 显着增加了纤连蛋白和 I 型胶原蛋白的产生。此外，未刺激的 MC 表达低水平的 CTGF 信息，并向培养基中分泌最少量的 CTGF 蛋白（36 至 38 kD）。然而，肝素钠处理导致培养基相关的 CTGF 增加四倍以上，这表明产生的大部分 CTGF 是细胞或基质结合的。 MC 暴露于 TGF-β、葡萄糖浓度增加或循环机械应变（糖尿病肾小球硬化症的所有致病因素）均显着诱导 CTGF 转录物的表达，而重组人 CTGF 能够自动诱导其自身表达。 TGF-β 和高葡萄糖（而非机械应变）刺激 CTGF 蛋白的伴随分泌，前者还诱导大量含有肝素结合域的小分子量形式的 CTGF (18 kD)。高浓度葡萄糖诱导 CTGF 蛋白是由 TGF-β 介导的，因为 TGF-β 中和抗体可阻断这种刺激。使用定量逆转录-PCR 的体内研究表明，尽管对照小鼠肾小球中的 CTGF 转录物较低，但在患糖尿病约 3.5 个月后，表达量增加了 28 倍。这种变化发生在糖尿病肾病病程早期，此时系膜轻度扩张，且不存在间质性疾病和蛋白尿。在整个肾皮质中观察到的 CTGF mRNA 升高显着降低（两倍）表明 CTGF 表达的主要改变是在肾小球中。这些结果表明，CTGF 上调是系膜基质积累和进行性肾小球硬化发病机制中的一个重要因素，作用于 TGF-β 下游。
Connective tissue growth factor (CTGF) is a peptide secreted by cultured endothelial cells and fibroblasts when stimulated by transforming growth factor-beta (TGF-beta), and is overexpressed during fibrotic processes in coronary arteries and in skin. To determine whether CTGF is implicated in the pathogenesis of diabetic glomerulosclerosis, cultured rat mesangial cells (MC) as well as kidney cortex and microdissected glomeruli were examined from obese, diabetic db/db mice and their normal counterparts. Exposure of MC to recombinant human CTGF significantly increased fibronectin and collagen type I production. Furthermore, unstimulated MC expressed low levels of CTGF message and secreted minimal amounts of CTGF protein (36 to 38 kD) into the media. However, sodium heparin treatment resulted in a greater than fourfold increase in media-associated CTGF, suggesting that the majority of CTGF produced was cell- or matrix-bound. Exposure of MC to TGF-beta, increased glucose concentrations, or cyclic mechanical strain, all causal factors in diabetic glomerulosclerosis, markedly induced the expression of CTGF transcripts, while recombinant human CTGF was able to autoinduce its own expression. TGF-beta and high glucose, but not mechanical strain, stimulated the concomitant secretion of CTGF protein, the former also inducing abundant quantities of a small molecular weight form of CTGF (18 kD) containing the heparin-binding domain. The induction of CTGF protein by a high glucose concentration was mediated by TGF-beta, since a TGF-beta-neutralizing antibody blocked this stimulation. In vivo studies using quantitative reverse transcription-PCR demonstrated that although CTGF transcripts were low in the glomeruli of control mice, expression was increased 28-fold after approximately 3.5 mo of diabetes. This change occurred early in the course of diabetic nephropathy when mesangial expansion was mild, and interstitial disease and proteinuria were absent. A substantially reduced elevation of CTGF mRNA (twofold) observed in whole kidney cortices indicated that the primary alteration of CTGF expression was in the glomerulus. These results suggest that CTGF upregulation is an important factor in the pathogenesis of mesangial matrix accumulation and progressive glomerulosclerosis, acting downstream of TGF-beta.