Involvement of SH2‐SH2‐SH3 domain of phospholipase Cγ1 in NF‐κB signaling

Abstract

To directly define the role of phospholipase CQ Q1 (PLCQ Q1) in NF-U UB activation, NF-U UB promoted luciferase reporter gene plasmid (pNF-U UB-Luc) was transfected into rat-3Y1 fibroblasts that overexpress whole PLCQ Q1 (PLCQ Q1-3Y1), src homology domains SH2-SH2-SH3 of PLCQ Q1 (SH223-3Y1) and v-src (Src-3Y1). Transient transfection with pNF-U UB-Luc remarkably increased the luciferase activity in all three transformants compared with normal rat-3Y1 cells. Pretreatment with inhibitors of protein tyrosine kinase reduced this increase in luciferase activity, but U73122 (a PLC inhibitor) did not. While PD98059, an inhibitor of mitogen activated protein kinase (MAPK), significantly reduced the luciferase activity, there was no effect by wortmannin and Ro-31-8220, inhibitors of phosphatidylinositol 3-kinase (PI3K) and protein kinase C (PKC), respectively. This study shows a direct evidence that the SH2-SH2-SH3 region of PLCQ Q1 contributes to the NF-U UB signaling and that MAPK, but not PI3K and PKC, is involved in SH2-SH2-SH3 mediated NF-U UB activation in these cells.z 2000 Federation of European Biochemical Societies.

Hematopoietic cell‐specific adapter proteins, SLP‐76 and BLNK, effectively activate NF‐AT as well as NF‐κB by Syk and Tec PTKs in non‐lymphoid cell lines

“…Interestingly, U73122 had a significant inhibitory effect on NF‐AT activation. On the other hand, U73122 had no effect on NF‐κB activation in 293T cells, indicating that PLC‐γ1 enzyme activity itself is not crucial in NF‐κB activation as described previously [19]. The data show that activation of endogenous PLC‐γ1 is crucial in CD8/ζ‐ and Syk‐mediated NF‐AT activation, but not NF‐κB activation in 293T cells.…”

“…3C). Recent study demonstrated that the SH2‐SH2‐SH3 region of PLC‐γ1 mediated NF‐κB activation in a rat fibroblast cell line, 3Y1 [19]. It was also demonstrated that TNF activates PLC‐γ2 via an upstream PTK to induce activation of PKC and PTKs, leading to NF‐κB activation in NCI‐H292 epithelial cells [20].…”

Oxidized Low-Density Lipoprotein Retards the Growth of Proliferating Cells by Inhibiting Nuclear Translocation of Cell Cycle Proteins

“…28 The acidic and basic fibroblast growth factors (aFGF and bFGF; Sigma) and transforming growth factor-␤1 (TGF-␤1, Sigma) were used at concentrations of 50 ng/mL, 10 ng/mL, and 5 ng/mL, respectively. Lipoproteindepleted serum was prepared as described by Auge et al 10 For experiments involving inhibitors, cells were pretreated for 15 minutes with 20 g/mL LY294002 (Sigma), 32 200 ng/mL calphostin C (Sigma), 8 or 3 g/mL U73122 (Sigma) 33 before exposure to oxLDL. The drugs remained in the media for the duration of the experiments.…”

Phospholipase Cγ1 links inflammation and tumorigenesis in colitis-associated cancer

“…Although a recent study did not report any direct evidence for the effects of PLCγ1 inhibition on attenuated colonic inflammation, we hypothesize that PLCγ1 contributes to the inflammatory response, including via the NF-κB signaling pathway [ 26 ]. To assess whether PLCγ1 may affect colonic inflammation, we applied the DSS-induced acute colitis model in PLCγ1 conditional knockout mice and their littermate controls (Figure 3A ).…”