RESUMEN
Objective To explore the protective mechanism of transdifferentiation of glomerular endothelial cells based on the differentiated embryonic chondrocyte gene 2 (DEC2) via the TGF-β/ROCK1 signaling pathway. Methods The 24 mice were randomly divided into sham group, UUO group, UUO combined with vector group and UUO combined with DEC2 group, with 6 mice in each group. A unilateral ureteral obstruction (UUO) model was established in each group, except for the sham group. In the UUO combined with vector group and UUO combined with DEC2 group, 10 μL (108 PFU) of vector or DEC2 was injected into each kidney on day 0 (immediately after UUO) under the guidance of the ultrasound system. The mice were sacrificed 14 days after the operation, and the kidneys were collected for histological examination and Western blot analysis: HE staining was used to observe the histological changes of kidneys, Masson staining to observe the renal fibrosis, and Western blot analysis to detect the protein expression. In vitro, normal human glomerular endothelial cells (GEnCs) was selected as the research objects. GEnCs stimulated with TGF-β were treated with ROCK1 inhibitor Y-27632 or DEC2 transfection. Western blot analysis was used to detect the expression of ROCK1, α-SMA, DEC2 and E-cadherin in GEnC exposed to transforming growth factor β (TGF-β). The localization of ROCK1 and DEC2 in GEnCs cells was detected by immunofluorescence cytochemistry. The relationship between the ROCK1 and DEC2 was confirmed by co-immunoprecipitation. Results Compared with the sham group, the UUO groups showed significant renal fibrosis and collagen accumulation on the 14th day. In the UUO groups, the expression of DEC2 and E-cadherin in the kidney tissue of the mice was significantly reduced, and the expression of α-SMA significantly increased. Compared with the UUO combined with vector group, the kidney fibrosis and collagen accumulation in the UUO combined with DEC2 group decreased, and the expression of ROCK1 and α-SMA decreased and the expression of DEC2 and E-cadherin increased in the kidney tissue. TGF-β enhanced the expression of ROCK1 and α-SMA in GEnCs cells in a time-dependent manner, and the levels of DEC2 and E-cadherin decreased. Treatment with the ROCK1 inhibitor Y-27632 partially abrogated the TGF-β-induced increase in the expression of ROCK1 and α-SMA and decrease in the expression of DEC2 and E-cadherin. In addition, transfection of GEnCs cells with DEC2 before TGF-β stimulation reduced the expression of ROCK1 and α-SMA, and increased the expression of DEC2 and E-cadherin. Immunofluorescence cytochemical staining showed that DEC2 co-localized with ROCK1 in GEnCs, and the co-immunoprecipitation showed that DEC2 and ROCK1 pulled down each other. Conclusions DEC2 is down-regulated in fibrotic renal tissue, while up-regulated DEC2 inhibits epithelial myofibroblast transdifferentiation and renal fibrosis of GEnC by blocking TGF-β/ROCK1 signaling pathway.