Effect of Slit2 on high glucose-induced renal tubular epithelial-mesenchymal transdifferentiation and its mechanism / 解放军医学杂志

ABSTRACT

Objective: To explore the effect of Slit2/ROBO1 protein (Slit2/ROBO1) signaling pathway in high glucose-induced epithelial-mesenchymal transdifferentiation (EMT) and its mechanism. Methods: Human renal tubular epithelial cells (HK-2) were cultured in vitro and subjected to high glucose concentration and time gradient experiments. First, for concentration gradient experiment, the sample was randomly divided into normal group, control group 1, control group 2, high glucose group 1, high glucose group 2. While for high glucose time gradient experiment, the sample was randomly divided into normal group, control group, high glucose 24 h group, high glucose 36 h group and high glucose 48 h group. Western blotting was used to detect the expression changes of Slit2, ROBO1, α-smooth muscle actin (α-SMA) and fibronectin in HK-2 cells, and then the optimal high glucose stimulation concentration and time were screened out. Slit2 over-expressed plasmid and negative control plasmid were transfected into HK-2 cells to verify the successful transfection, the cells were then randomly divided into normal group, control group, high glucose group, high glucose empty group and high glucose Slit2 group. The total protein was extracted after stimulation with optimal high glucose concentration and time, and Western blotting was then performed to detect the change in expression of fibronectin and α-SMA. Results: In the high glucose concentration gradient experiment, the expression of Slit2 declined significantly in high glucose group 1(0.647±0.048) and high glucose group 2(0.210±0.023) than in the normal group (1.000±0.050); the expression of ROBO1 declined significantly in high glucose group 1(0.703±0.041) and high glucose group 2(0.303±0.022) than in the normal group (1.000±0.057); while the expression of fibronectin increased significantly in high glucose group 1(1.953±0.042) and high glucose group 2(2.997±0.078) than in the normal group (0.990±0.059), and the expression of α-SMA increased significantly in high glucose group 1(1.767±0.012) and high glucose group 2(2.427±0.059) than in the normal group (1.033±0.067), all the differences were of statistical significance(P<0.05). Compared with the high glucose group 1, the expressions of Slit2 and ROBO1 decreased, and of fibronectin and α-SMA increased significantly in the high glucose group 2(P<0.05). In the high glucose time gradient experiment, compared with the normal group, the expressions of Slit2 in high glucose 36 h group and high glucose 48 h group decreased (0.943±0.032 vs. 0.557±0.020, 0.450±0.055, respectively), and the expression of ROBO1 decreased (1.000±0.058 vs. 0.600±0.023, 0.227±0.028, respectively). Compared with the normal group, the expression of fibronectin increased significantly in high glucose 24 h group, high glucose 36 h group and high glucose 48 h group (0.970±0.040 vs. 1.247±0.052, 1.733±0.084, 2.780±0.090, respectively), and the expression of α-SMA increased significantly in high glucose 24 h group, high glucose 36 h group and high glucose 48 h group (1.033±0.067 vs. 1.277±0.041, 1.767±0.120, 2.537±0.078, respectively), and the difference was statistically significant (P<0.05). Compared with high glucose 24 h group, the expression of Slit2 declined significantly in high glucose 36 h group and high glucose 48 h group(0.893±0.034 vs. 0.557±0.020, 0.450±0.055, respectively), and the expression of ROBO1 declined significantly (0.930±0.025 vs. 0.600±0.023, 0.227±0.028, respectively), the expressions of fibronectin and α-SMA increased significantly with statistical significance (P<0.05). Compared with high glucose 36 h group, the expression of Slit2 and ROBO1 declined significantly, and the expression of fibronectin and α-SMA increased significantly in high glucose 48 h group (P<0.05). In the high glucose environment, and achieving Slit2 overexpression and negative control plasmid transfection, the expression of fibronectin increased significantly in high glucose group, high glucose+empty group and high glucose+Slit2 group (2.760±0.012, 2.667±0.027, 1.460±0.034, respectively) than in normal group (1.000±0.058); the expression of α-SMA increased also in high glucose group, high glucose+empty group and high glucose+Slit2 group (2.487±0.048, 2.557±0.037, 1.270±0.017, respectively) than in normal group (1.000±0.050) with statistical significance (P<0.05). Compared with the high glucose+empty group, the expression of fibronectin and α-SMA declined significantly in the high glucose+Slit2 group(P<0.05). Conclusion: The decreased expression of Slit2 and ROBO1 is involved in the high glucose-induced renal tubular EMT. Overexpression of Slit2 may significantly inhibit the high glucose-induced EMT.