ABSTRACT
Objective To investigate the role of phosphatidylinositol 3 kinase (PI3K)/protein kinase B (Akt) signaling pathway in Dexamethasone (DEX) inhibiting podocytes apoptosis which was induced by Puromycin (PAN).Methods Mouse glomerular podocytes were cultured in vitro,and were divided into control group,dimethyl sulfoxide (DMSO) group,PAN group,DEX group,and LY294002 (inhibitor of PI3 K) group.The mRNA expression of CD2-associated protein (CD2AP) was measured by using real time fluorescent quantitative polymerase chain reaction,and intracellular distribution was detected by using indirect immunofluorescence staining.Co localization of CD2AP and p85 was detected by using confocal fluorescence microscopy.The expressions of Akt,phosphorylated (p)-Akt,glycogen synthase kinase-3β (GSK3 β) and phosphorylated (p)-GSK3β were evaluated by using Western blot.Results The expressions of CD2AP mRNA in PAN group at each time point (8 h,24 h,48 h) (1.11 ± 0.16,0.78 ±0.09,0.56 ± 0.43) were significantly lower than those in the control group (1.90 ± 0.26,2.09 ± 0.12,2.28 ±0.95),and the differences were statistically significant (all P ＜ 0.05);CD2AP distributed in foot process with uniform filament and discontinuous coarse particle around perinuclear;CD2AP and p85 distributed in cell membrane and cytoplasm evenly in control group,but accumulated in nuclei in the PAN group.The expressions of CD2AP mRNA in DEX group at each time point (8 h,24 h,48 h) (1.53 ± 0.14,2.15 ± 0.27,2.13 ± 0.15) were significantly higher than those in the PAN group,and the differences were also statistically significant (all P ＜ 0.05);the distribution density and range of CD2AP were greater than those in the PAN group,and the accumulation with p85 in nuclei decreased obviously.The expressions of p-Akt and p-GSK3β were inhibited by PAN in a dose-dependent manner (P ＜0.05).The expressions of p-Akt and p-GSK3 β were lowest after PAN stimulated at 15 min and 30 min respectively.However,the expressions of p-Akt and p-GSK3 β increased depending on the concentration of DEX (P ＜ 0.05).In addition,the expressions of p-Akt and p-GSK3 β could be blocked by LY294002 (P ＜ 0.01).Conclusion DEX can protect podocytes and inhibit podocytes apoptosis through stabilizing the expression and distribution of CD2AP.The stale expression of PI3K/Akt signaling pathway is the key factor in DEX protecting podocytes.