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AIM:To explore whether down-regulation of peroxisome proliferator-activated receptor γ coactivator (PGC)-1α induces podocyte apoptosis and its mechanism.METHODS:The podocytes were cultured under high glucose (HG) condition and the cell apoptosis was analyzed by flow cytometry.The methods of real-time PCR and Western blot were used to analyze the mRNA and protein expression of related molecules in the control, HG-treated or siRNA-treated podocytes.RESULTS:The expression PGC-1α at mRNA and protein levels was significantly decreased in HG-injured podocytes.Down-regulation of PGC-1α expression in vitro by siRNA resulted in podocyte apoptosis.The nuclear protein expression of nuclear factor of activated T-cells (NFAT) was significantly increased in HG injured podocytes, indicating the NFAT activation.Down-regulation of PGC-1α expression also decreased the nuclear protein expression of NFAT.Moreover, silencing of NFAT expression by siRNA significantly abolished PGC-1α deficiency-induced podocyte apoptosis.CONCLUSION: Down-regulation of PGC-1α induces podocyte apoptosis.NFAT mediates PGC-1α deficiency-induced podocyte apoptosis.
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Objective To evaluate the effect of the activity of Ca2+/CaN-NFATc on the activation and prolfferation of lymphocyte in asthmatic rats.Methods The rats of the asthma group and the CsA group were sensitized and challenged by ovalbumin.So did the control group with saline instead.Lymphocyte was separated from spleen and cultured for 24 hours,and PHA-p (5 μg/ml) was added to the culture medium in every group,CsA ( 1.0 μg/ml) was added to the CsA group,respectively.The concentration of [ Ca2+ ] i,the activity of CaN,the protein expression of dephosphorylated NFATc and Cyclin E in T lymphocyte were assayed.The level of IL-4 and IL-2 in culture supernatants was measured,and the cell cycle distribution of lymphocyte was analyzed.ResultsWhen compared to the control group,the activity of Ca2+/CaN-NFATc [ (81.21 4-14.39) vs (63.66 ±9.02) ] was increased and the protein expression of CyclinE [ (0.9327 ±0.0370) vs (0.8374 ±0.0637) ] was higher in Lymphocyte of the asthma group ( P＜0.05,P ＜0.01,respectively).The percentage of lymphocyte in the S phase [ (7.8600±2.8241) vs (4.0270 ± 1.8650) ] and S + G2/M phase [ ( 10.6700±3.3850) vs (5.8740 ± 1.4389) ] was higher;however,the percentage of G0/G1 phase [ (89.3300 ± 3.3850) vs (94.1260± 1.4389 )] was lower in asthma group ( all P ＜ 0.01 ).The level of IL-4 [ ( 1.55 ± 0.19) pg/ml vs (0.99 ± 0.12 ) pg/ml ] and the IL-4/ IL-2 ratio [ (0.81 ±0.12) vs (0.49 ±0.49) ] in culture supernatants of the asthma group were higher than those of the control group ( all P ＜0.01 ).While the activity of Ca2+/CaN-NFATc (47.19 ±7.16)was decreased and the protein expression of Cyclin E (0.6840 ± 0.0485 ) was reduced in lymphocyte in CsA group(all P ＜0.01 ),the percentage of lymphocyte in the S phase (4.8600 ± 1.9595) and S + G2/M phase (7.9900 ± 1.9405) was decreased and the percentage of G0/G1 phase (92.2100 ± 1.9267) was increased ( all P ＜ 0.05 ),and the level of IL-4 (0.47 ± 0.09 ) pg/ml and the ratio of IL-4/ IL-2 (0.78 ±0.20) was lower in culture supernatants in the CsA group than that of the asthma group( all P ＜ 0.01 ).There was a positive correlation between the protein expression of dephosphorylated NFATc and the protein expression of CyclinE in Lymphocyte,so did between the protein expression of NFATc and the level of IL-4 in culture supernatants( r =0.711,P ＜0.01 and r =0.749,P ＜0.01.respectively).Conclusions The activity of Ca2+/CaN-NFATc was increased in lymphocyte of the asthmatic rats.Its increasing might result in the imbalance of Th1/Th2 by promoting the expression of IL-4 and might lead to the proliferation of lymphocyte by promoting the Cyclin E expression.