Department of Cellular and Molecular Biology and Pathology, Federico II University of Naples, Via Pansini 5, 80131, Naples, Italy.
Diabetologia. 2009 Dec;52(12):2642-52. doi: 10.1007/s00125-009-1528-z. Epub 2009 Sep 30.
AIMS/HYPOTHESIS: Overproduction of phosphoprotein enriched in diabetes (PED, also known as phosphoprotein enriched in astrocytes-15 [PEA-15]) is a common feature of type 2 diabetes and impairs insulin action in cultured cells and in mice. Nevertheless, the potential role of PED in diabetic complications is still unknown.
We studied the effect of PED overproduction and depletion on kidney function in animal and cellular models.
Transgenic mice overexpressing PED (PEDTg) featured age-dependent increases of plasma creatinine levels and urinary volume, accompanied by expansion of the mesangial area, compared with wild-type littermates. Serum and kidney levels of TGF-beta1 were also higher in 6- and 9-month-old PEDTg. Overexpression of PED in human kidney 2 cells significantly increased TGF-beta1 levels, SMAD family members (SMAD)2/3 phosphorylation and fibronectin production. Opposite results were obtained following genetic silencing of PED in human kidney 2 cells by antisense oligonucleotides. Inhibition of phospholipase D and protein kinase C-beta by 2-butanol and LY373196 respectively reduced TGF-beta1, SMAD2/3 phosphorylation and fibronectin production. Moreover, inhibition of TGF-beta1 receptor activity and SMAD2/3 production by SB431542 and antisense oligonucleotides respectively reduced fibronectin secretion by about 50%. TGF-beta1 circulating levels were significantly reduced in Ped knockout mice and positively correlated with PED content in peripheral blood leucocytes of type 2 diabetic patients.
CONCLUSIONS/INTERPRETATION: These data indicate that PED regulates fibronectin production via phospholipase D/protein kinase C-beta and TGF-beta1/SMAD pathways in kidney cells. Raised PED levels may therefore contribute to the abnormal accumulation of extracellular matrix and renal dysfunction in diabetes.
目的/假设：富含磷酸蛋白的糖尿病（PED，也称为富含星形胶质细胞-15 [PEA-15] 的磷酸蛋白）在 2 型糖尿病中是一种常见特征，可损害培养细胞和小鼠中的胰岛素作用。然而，PED 在糖尿病并发症中的潜在作用尚不清楚。
我们在动物和细胞模型中研究了 PED 过度产生和耗竭对肾功能的影响。
与野生型同窝仔相比，过表达 PED 的转基因小鼠（PEDTg）表现出年龄依赖性的血浆肌酐水平和尿量增加，同时肾小球系膜区扩张。6 月龄和 9 月龄 PEDTg 的血清和肾脏 TGF-β1 水平也较高。在人肾 2 细胞中过表达 PED 显著增加了 TGF-β1 水平、SMAD 家族成员（SMAD）2/3 磷酸化和纤维连接蛋白产生。通过反义寡核苷酸对人肾 2 细胞中的 PED 进行基因沉默可获得相反的结果。用 2-丁醇和 LY373196 分别抑制磷脂酶 D 和蛋白激酶 C-β，可降低 TGF-β1、SMAD2/3 磷酸化和纤维连接蛋白产生。此外，用 SB431542 和反义寡核苷酸分别抑制 TGF-β1 受体活性和 SMAD2/3 产生，可使纤维连接蛋白分泌减少约 50%。PED 敲除小鼠的 TGF-β1 循环水平显著降低，与 2 型糖尿病患者外周血白细胞中的 PED 含量呈正相关。
结论/解释：这些数据表明，PED 通过肾细胞中的磷脂酶 D/蛋白激酶 C-β 和 TGF-β1/SMAD 途径调节纤维连接蛋白的产生。因此，升高的 PED 水平可能导致糖尿病中外源性细胞外基质的异常积累和肾功能障碍。
