PC-PLC/PKC-α pathway involves in TNF-α-induced IP3R1 expression in human mesangial cells

Abstract

Objective To explore the effects of TNF-α on the expression of IP33R1 mRNA and protein in human mesangial cells (HMCs) and elucidate the mechnism of TNF-α indnces the IP3R1 expression in the occurrence of hepatorenal syndrome (HRS).Methods HMCs was stimulated by tumor (TNF-α) with 100 ng/mL for different hours (2,4,8,24 hours).The expression change of IP3R1 mRNA and protein were detected by quantitative real-time polymerase chain reaction and immunoblot assay.Several inhibitors including D609,U73122,PP1,Safingol,Rottlerin and non-radioactive PKC assay to examine the mechanism of signal transduction of TNF-α-regulated IP3R1 in HMCs.Results The levels of IP3R1 mRNA at 2 h post-TNF-α exposure were significantly enhanced and reached peak at 8 h in HMCs (P ＜ 0.01),then descened at 24 h (P ＜ 0.01).The levels of IP3R1 protein at 4 h post-TNF-α exposure were obviously increased and reached peak at 24 h post-TNF-α exposure (P ＜ 0.01).Compared with the control group,safingol (PKC-α inhibitor) and D609 (PC-PLC inhibitor) each significantly suppressed TNF-α-induced expression of IP3R1 mRNA (3.30 ± 0.81) vs.(1.95 ± 0.130,P ＜ 0.05 ; (2.10 ± 0.49),P ＜ 0.01 andIP3R1 protein (3.09±0.13) vs.(1.86+0.39),P＜0.01; (1.98±0.02),P＜0.01.TNF-αpromoted autophosphorylation,and hence the activation,of PKC-α with maximal phosphorylation that occurred 8 h post-stimulation measured by non-radioactive PKC assay,and the effect was marked attenuated by pretreated with D609 or safingol.Conclusions TNF-α increased the expression of IP3R1 and this was mediated,at least in part,through the PC-PLC/PKC-α signaling pathways in HMCs. Key words: TNF-α; Hepatorenal syndrome; HMCs; IP3R1; PKC-α; PC-PLC