Zhu Lin, Zhao Song, Liu Shuxia, Liu Qingjuan, Li Fan, Hao Jun
Department of Electromyogram, 3rd Affiliated Hospital of Hebei Medical University, Shijiazhuang, Hebei, China.
Department of Pathology, Hebei Medical University, Shijiazhuang, Hebei, China.
J Cell Biochem. 2016 May;117(5):1187-98. doi: 10.1002/jcb.25402. Epub 2015 Oct 18.
Extracellular matrix accumulation and fibrosis are the features of diabetic nephropathy. PI3K (phosphatidylinositol 3-kinase)/Akt (protein kinase B) signal pathway and its inhibitor PTEN (phosphatase and tensin homolog deleted on chromosome 10) are revealed to modulate renal fibrosis. However, the exact mechanism is still not well known. In the present study we found that compared with normal mice, diabetic mice showed decreased PTEN, increased phospho-Akt (Ser 473), phospho-Akt (Thr 308), CTGF (connective tissue growth factor), α-SMA (α-smooth muscle actin), and matricellular protein in kidney. Knocking down of PTEN caused an increase in phospho-Akt (Ser 473), phospho-Akt (Thr 308), CTGF, secreted fibronectin, and secreted Col 3 in HKC cells (human renal tubular epithelial cells). Again, in vitro experiment revealed 1.89, 2.18, 1.92, 3.06, 2.06-fold increases of phospho-Akt (Ser 473), phospho-Akt (Thr 308), CTGF, secreted fibronectin, and secreted Col 3 in high glucose-stimulated HKC cells in comparison with normal control cells. Furthermore, knocking down of CTGF reversed increased secreted fibronectin and Col 3 in high glucose-treated HKC cells. Moreover, transfection of PTEN expression vector prevented high glucose-caused these changes in HKC cells. Especially, CTGF expression, secretion of fibronectin and Col 3 were, respectively, decreased by 38.81, 53.85, and 39.12%. The treatment of LY294002 inhibited phospho-Akt (Ser 473) and phospho-Akt (Thr 308) expression followed by decreased CTGF, secretory fibronectin and secretory Col 3 in high glucose-treated HKC cells. In the end our study suggests that PTEN regulates renal extracellular matrix production via activated Akt and increased CTGF in diabetes mellitus.
细胞外基质积聚和纤维化是糖尿病肾病的特征。已发现磷脂酰肌醇3激酶（PI3K）/蛋白激酶B（Akt）信号通路及其抑制剂第10号染色体缺失的磷酸酶和张力蛋白同源物（PTEN）可调节肾纤维化。然而，确切机制仍不清楚。在本研究中，我们发现与正常小鼠相比，糖尿病小鼠肾脏中的PTEN降低，磷酸化Akt（Ser 473）、磷酸化Akt（Thr 308）、结缔组织生长因子（CTGF）、α平滑肌肌动蛋白（α-SMA）和基质细胞蛋白增加。敲低PTEN导致人肾小管上皮细胞（HKC细胞）中磷酸化Akt（Ser 473）、磷酸化Akt（Thr 308）、CTGF、分泌型纤连蛋白和分泌型胶原3增加。同样，体外实验显示，与正常对照细胞相比，高糖刺激的HKC细胞中磷酸化Akt（Ser 473）、磷酸化Akt（Thr 308）、CTGF、分泌型纤连蛋白和分泌型胶原3分别增加了1.89、2.18、1.92、3.06和2.06倍。此外，敲低CTGF可逆转高糖处理的HKC细胞中分泌型纤连蛋白和胶原3的增加。此外，转染PTEN表达载体可防止高糖引起的HKC细胞中的这些变化。特别是，CTGF表达、纤连蛋白和胶原3的分泌分别降低了38.81%、53.85%和39.12%。LY294002处理抑制了高糖处理的HKC细胞中磷酸化Akt（Ser 473）和磷酸化Akt（Thr 308）的表达，随后CTGF、分泌型纤连蛋白和分泌型胶原3减少。最后，我们的研究表明，在糖尿病中，PTEN通过激活Akt和增加CTGF来调节肾脏细胞外基质的产生。
