TNFα-induced IP3R1 expression through TNFR1/PC-PLC/PKCα and TNFR2 signalling pathways in human mesangial cell.
BACKGROUND
Little information is available regarding the mechanisms involved in cytokine-induced type 1 inositol 1,4,5-trisphosphate receptor (IP(3)R1) expression in human mesangial cells (HMCs) in the occurrence of hepatorenal syndrome (HRS). Over-expression of IP(3)R1 would enhance both IP(3)-binding activity and sensitivity. We hypothesize that it is possible that increased IP(3)R1, induced by TNFα, would lead to increased IP(3) sensitivity in response to a variety of vasoconstrictors, and promote HMC contraction and thus lead to reduced GFP, promoting HRS occurrence and development.


METHODS
Quantitative real-time polymerase chain reaction and immunoblot assay were used to examine the effects of TNFα on IP(3)R1 mRNA and protein expression. Several inhibitors of kinases, depletion PKC, over-expression of dominant-negative mutant of PKC and non-radioactive PKC assay were used to examine the mechanism of signal transduction of TNFα-regulated IP(3)R1 in HMCs.


RESULTS
TNFα increased IP(3)R1 mRNA and protein expression in HMCs, an effect that was blocked by prolonged incubated chronic PMA, D609, safingol and also by transfection with domain-negative PKCα construct. TNFα activated and promoted autophosphorylation of the PKCα. In addition, both anti-TNFR1 and anti-TNFR2 antibodies blocked TNFα-induced IP(3)R1 protein expression, while only anti-TNFR1 antibodies but not anti-TNFR2 antibodies attenuated TNFα-induced PKCα activity.


CONCLUSIONS
TNFα increased the expression of IP(3)R1, and this was mediated, at least in part, through the TNFR1/PC-PLC/PKCα and TNFR2 signalling pathways in HMCs.
Wang
Yu-rong
YR
Department of Infectious Diseases, The First Affiliated Hospital, China Medical University, ShenYang City, LiaoNing Province, China.
Li
Zhen-guo
ZG
Fu
Jin-long
JL
Wang
Zhao-han
ZH
Wen
Ying
Y
Liu
Pei
P
D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D006530:Hepatorenal Syndrome / Q000378:metabolism / Q000473:pathology; D006801:Humans; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000235:genetics / Q000378:metabolism*; D050527:Mesangial Cells / Q000187:drug effects* / Q000378:metabolism; D051571:Protein Kinase C-alpha / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000235:genetics / Q000378:metabolism*; D047889:Receptors, Tumor Necrosis Factor, Type II / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D010738:Type C Phospholipases / Q000378:metabolism*
D053496:Inositol 1,4,5-Trisphosphate Receptors; D012333:RNA, Messenger; D047888:Receptors, Tumor Necrosis Factor, Type I; D047889:Receptors, Tumor Necrosis Factor, Type II; D014409:Tumor Necrosis Factor-alpha; D015544:Inositol 1,4,5-Trisphosphate; D051571:Protein Kinase C-alpha; D010738:Type C Phospholipases; C105598:phosphatidylcholine-specific phospholipase C; D002118:Calcium