PKCα signaling pathway involves in TNF-α-induced IP_3R1 expression in human mesangial cells

BACKGROUND:This study aimed to explore the effects of TNF-a on the expression of IP_3R1mRNA and protein in human mesangial cells(HMCs),and to elucidate the mechanism of TNF-a relating to IP_3R1 expression in the occurrence of hepatorenal syndrome(HRS).METHODS:HMCs were stimulated by tumor(TNF-a) with 100 ng/mL for different hours(2,4,8,and 24 hours).The expression changes of IP_3R1 mRNA and protein were detected by quantitative real-time polymerase chain reaction and immunoblotting.Several inhibitors including D609,U73122,PP1,safingol,rottlerin and non-radioactive protein kinase C(PKC) were used to examine the mechanism of signal transduction ofTNF-a-regulated IP_3R1 in HMCs.RESULTS:The levels of IP_3R1 mRNA at 2 hours after TNF-a exposure were significantly enhanced and peaked at 8 hours in HMCs(P<0.01),then descended at 24 hours(P<0.01).The levels of IP_3R1 protein at 4 hours after TNF-a exposure were obviously increased and peaked at24 hours after TNF-a exposure(P<0.01).Compared to the control group,safingol(PKCa inhibitor)and D609(phosphatidylcholine-specific phospholipase C inhibitor) significantly blocked the TNF-ainduced expression of IP_3R1 mRNA(3.30±0.81 vs.1.95±0.13,P<0.05;2.10±0.49,P<0.01) and IP_3R1protein(3.09±0.13 vs.1.86+0.39,P<0.01;1.98±0.02,P<0.01).TNF-a promoted PKCa activation with maximal PKCa phosphorylation that occurred 8 hours after stimulation measured by non-radioactive PKC assay,and the effect was markedly attenuated by pretreatment with D609 or safingol.CONCLUSION:TNF-a increased the expression of IP_3R1 and this was mediated,at least in part,through the PC-PLC/PKCa signaling pathways in HMCs.

Expression of Nrf2/ARE pathway in diabetic nephropathy and renal protection of Qihuang Bushen Xiezhuo Formula

Objective:To investigate the effect of Qihuang Bushen Xiezhuo Formula on the expression of the nuclear factor E2 related factor 2(Nrf2)/antioxidant response element(ARE)signaling pathway of human glomerular mesangial cells(HMC)in high glucose medium and its protective effect on oxidative stress.Methods:The HMC were cultured in vitro to prepare normal rat serum.The rats were intragastrically administered with irbesartan and Qihuang Bushen Xiezhuo Formula.The serum containing the drugs was prepared after the blood concentration was reached.The rats were divided into the control group,the high glucose group,the irbesartan group and the Qihuang Bushen Xiezhuo Formula group.The HMC of the control group was cultured with normal rat serum(10%serum concentration)medium,while that of the high glucose group was cultured with high glucose medium of rat serum(10%serum concentration).The irbesartan group and the Qihuang Bushen Xiezhuo Formula group were respectively treated with 10%irbesartan and 10%Qihuang Bushen Xiezhuo Formula in serum high glucose medium.After 48 h of culture,the relevant indicators were collected and detected.The mRNA expression levels of Nrf2,gamma-glutamylcysteine synthetase(γ-GCS)and superoxide dismutase(SOD)in each group were detected by real-time PCR.The expressions ofγ-GCS and SOD were detected by immunohistochemistry.The protein expressions ofγ-GCS and SOD in HMC of each group were observed by Western Blot.Results:The expressions of Nrf2,γ-GCS,SOD mRNA and protein in experimental cells of each group were low in the control group,while those in the high glucose group were decreased as compared with the control group(P<0.05).After interference of irbesartan and Qihuang Bushen Xiezhuo Formula the expressions were increased,and the increase in Qihuang Bushen Xiezhuo Formula group was more significant(P<0.05).Conclusion:Qihuang Bushen Xiezhuo Formula can improve HMC oxidative stress injury in high glucose culture,and its mechanism may be achieved by activating Nrf2 and its related downstream proteinsγ-GCS and SOD.