High glucose increases podocyte autophagy through PI3K-AKT-mTOR signaling pathway / 中华肾脏病杂志

Objective To evaluate the effects of high glucose on autophagy and apoptosis of podocyte and explore the signaling pathway in high glucose-induce podocyte autophagy.Methods Differentiated mouse podocytes were exposed to high glucose(30 mmol/L) or rapamycin (autophagy enhancer,1 μg/L) or LY294002 (a selective PI3K inhibitor,50 mmol/L) for 24 h.The formations of autophagy were observed by electron microscopy and acridine orange staining.Apoptosis was evaluated by flow cytometry.The expression of autophagy protein LC3-Ⅱ/Ⅰ and Beclin-1 as well as the phosphorylation of AKT and mTOR were examined by Western blotting analysis.Results High glucose induced podocytes apoptosis,increased autophagy and the expression of autophagy-associated proteins (all P ＜ 0.05).Rapamycin further increased the expression of LC3-Ⅱ and Beclin-1 protein (all P ＜ 0.05),but LY294002 inhibited partialiy the protein expression of LC3-Ⅱ and Beclin-1 induced by high glucose (both P ＜ 0.05).Treatment with rapamycin increased the phosphorylation of AKT,but reduced that of mTOR in podocytes.Moreover,LY294002 inhibited phosphorylation of both AKT and mTOR (both P ＜ 0.05).Conclusions High glucose promotes podocyte autophagy and apoptosis.High glucose-induced autophagy is mediated partly through PI3K-AKT-mTOR signaling pathway.

Angiotensin Ⅱ induces podocyte c-Abl expression change / 中华肾脏病杂志

ObjectiveTo evaluate the effects of angiotensin Ⅱ (Ang Ⅱ )infusion on renal c-Abl expression in vivo,and on podocyte c-Abl expression change in cultured mouse podocytes.Methods Twenty four male Sprague-Dawley rats (Group C,D,E and F) were assigned to receive Ang Ⅱ(400 ng· kg-1 min-1) by osmotic minipump and of which 12 rats (Group D and F) were assigned to receive telmisartan (3 mg·kg-1·d-1),six rats received normal saline(Group B),and six rats were used as normal control(Group A).Animals were sacrificed at day 14 (Group C and D),day 28 (Group E and F) respectively.Conditionally immortalized mouse podocytes were used in vitro.Podocytes were studied 2 weeks after thermoswitching from 33℃ to 37℃.Cells were fetal bovine serum(FBS) starved for at least 12 hours prior to stimulation.The cultured podocytes were treated withAngⅡdosesranging from10 -9 mol/L to10 -6 mol/L andfor differenthours.Expression of renal and podocytes c-Abl was examined by immunofluorescence staining,real-time PCR and Western blotting.Results(1) Distribution of c-Abl expression was mainly in the cytoplasm and nuclear of the podocytes in vivo and in vitro. (2) Expressions of c-Abl mRNA and protein wereincreasedinAng Ⅱ-infusedratpodocytesandAng Ⅱ-inducedculturedmouse podocytes(P＜0.05),and the effects of Ang Ⅱ were dose-dependent and time-dependent in vitro.Conclusion There are c-Abl mRNA and protein expression in podocytes,and c-Abl may play a critical role in the pathogenesis of Ang Ⅱ -induced podocyte injury.