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. BACKGROUND: This study aimed to explore the effects of TNF-a on the expression of IP_3R1 mRNA 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. Selective inhibitors including D609, U73122, PP1, safingol, rottlerin and non-radioactive protein kinase C (PKC) were used to examine the mechanism of signal transduction of TNF-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 at 24 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, ) 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 for 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 increased the expression of IP_3R1 and this was mediated, at least in part, through the PC-PLC / PKCa signaling pathways in HMCs.