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The molecular mechanism of increase of TGF-β expression in diabetic glomeruli

糖尿病肾小球TGF-β表达增加的分子机制

基本信息

批准号：
09470218
负责人：
KIKKAWA Ryuichi
金额：
$ 8.51万
依托单位：
Shiga University of Medical Science
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1999
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09470218/
关键词：
Diabetic nephoropathy TGF-β Mesangial cell Glomerular hypertension Cyclic stretch Gene expression

项目摘要

The aim of this study is to clarify the molecular mechanism of the increased TGF-β expression in diabetic glomeruli or mesangial cells under high glucose conditions. First, we examined the effects to troglitazone, a PPARγ agonist, or PKCβ inhibitor (LY333531) on the development of diabetic nephropathy using animal models of diabetics. In STZ-induced diabetic rat glomeruli, the content of DAG, the activities of PKC and ERK were increased compared to control rats. The expression of TGF-β fibronection was also increased, and these abnormalities were normalized by troglitazone treatment. The effect of LY333531 was evaluated using dBdB mice, a model for type2 diabetes. In the glomeruli of dBdB mice, the increased amounts of TGF-β, type4 collagen and fibronectin were observed, which were prevented by LY333531 treatment. LY333531 also prevented the mesangial expansion or the increase of urinary albumin excretion in dB/dB mice.We next examined the regulation of TGF-β expression in cultured rat mesangial cells. In the cells under high glucose condition or stimulated by mechanical stretching, in vitro model for glomerular hypertension seen in diabetes mellitus, ERK activity was increased. High glucose induced activation of ERK was inhibited by PKC inhibitors, whereas stretch-induced ERK activation of ERK was not inhibited by PKC inhibitors, but by tyrosine kinase inhibitor. Mechanical stretching also increased the expression of TGF-β and fibronectin, and these increase were inhibited by MEK inhibitor.These results indicated that the expression of TGF-β was increased via PKC-ERK-dependent mechanism in diabetic glomeruli. The increase of ERK activity in diabetic state might be the consequence of synergistic effect of high glucose itself and mechanical stretching produced by glomerular hypertension, lead to the overproduction of TGF-β and extracellular matrix proteins, and thus involve the development and progression of diabetic glomerulosclerosis.

本研究的目的是阐明高糖条件下糖尿病肾小球或系膜细胞中TGF-β表达增加的分子机制。首先，我们使用糖尿病动物模型研究了曲格列酮（一种 PPARγ 激动剂或 PKCβ 抑制剂）（LY333531）对糖尿病肾病发展的影响。在STZ诱导的糖尿病大鼠肾小球中，与对照大鼠相比，DAG的含量、PKC和ERK的活性增加。 TGF-β 纤维连接的表达也增加，并且这些异常通过曲格列酮治疗得以正常化。使用 dBdB 小鼠（2 型糖尿病模型）评估 LY333531 的效果。在 dBdB 小鼠的肾小球中，观察到 TGF-β、4 型胶原和纤连蛋白含量增加，而 LY333531 治疗可阻止这种情况的发生。 LY333531还阻止dB/dB小鼠的肾小球系膜扩张或尿白蛋白排泄的增加。接下来我们检查了培养的大鼠肾小球系膜细胞中TGF-β表达的调节。在糖尿病肾小球高血压的体外模型中，在高葡萄糖条件下或受到机械拉伸刺激的细胞中，ERK活性增加。高糖诱导的 ERK 激活被 PKC 抑制剂抑制，而拉伸诱导的 ERK 激活不受 PKC 抑制剂抑制，而是被酪氨酸激酶抑制剂抑制。机械拉伸还增加了TGF-β和纤连蛋白的表达，并且这些增加被MEK抑制剂抑制。这些结果表明，糖尿病肾小球中TGF-β的表达通过PKC-ERK依赖性机制增加。糖尿病状态下ERK活性的升高可能是高糖本身与肾小球高血压产生的机械拉伸协同作用的结果，导致TGF-β和细胞外基质蛋白的过量产生，从而参与糖尿病肾小球硬化的发生和发展。