Dexamethasone reduces podocyte injury through the PTEN-PI3K/Akt signaling pathway
Objective: To study the role of Akt and its downstream molecules in the PTEN-PI3K/Akt signaling pathway, namely,GSK3β and Bad, in the Dexamethasone(DEX)-mediated regulation of PAN-induced glomerular podocyte injury and to elucidate the molecular mechanism of podocyte injury regulation. Methods: Glomerular podocytes (MPC5) were cultured in vitro and divided into four groups: the control group, PTEN silencing group (siPTEN group), puromycin group (PAN group), and puromycin group + DEX group (PAN+
... p + DEX group (PAN+ DEX group). The cells in each group were treated for 8h, 24h, and 48h, and then, the experiment was carried out. The cells in the control group were cultured in RPMI 1640 with 0.02% DMSO, the cells in the siPTEN group were used to construct a silencing kit, the podocytes in the PAN group were treated with puromycin (final concentration of 50μg/ml), and the podocytes in the DEX+PAN group were pretreated with 0.1μmol/L DEX followed by PAN (final concentration of 50μg/ml). An inverted phase contrast microscope was used to observe the morphological changes in the podocytes and the changes in the cell body area in each group, laser confocal microscopy was used to detect the expression and distribution of the PTEN protein, and flow cytometry was used to detect and analyze the apoptosis rate and mitochondrial membrane potential of each group of podocytes. Western blot was used to detect the expression of the PTEN, P-Akt, Akt, P-GSK3β and GSK3β proteins in each group of podocytes, and transmission electron microscopy was used to observe the changes in the morphology and structure of each group of podocytes. Results: After PAN was used to injure the podocytes, the expression of the PTEN protein decreased, the rate of apoptosis increased, and the flux of autophagy was inhibited. DEX treatment reversed the changes described above.After PAN was used to injure the podocytes, the expression of p-Ak and p-GSK3β decreased, and DEX reversed these effects on the expression of p-Akt and p-GSK3β in the podocytes. Compared with the control group, in the PAN group, the mitochondria gradually swelled and rounded, mitochondrial cristae arrangement became disordered, mitochondrial autophagy was inhibited; DEX reversed the changes described above after the PTEN gene was silenced. Conclusion: This study confirmed that PAN can inhibit podocyte autophagy and induce podocyte damage. DEX can reduce the PAN-induced suppression of podocyte autophagy, enhance podocyte autophagy, and ameliorate podocyte damage. The protective mechanism may be through the upregulation of PTEN expression, which is achieved by inhibiting the activation of the PI3K/Akt signaling pathway.