Abstract
Rationale We demonstrated in CD34 + peripheral blood derived- human MC that wortmannin, a PI-3kinase inhibitor, does not affect PLC-γ1-dependent degranulation after FcϵRI aggregation, suggesting that PLC-γ1 regulated responses are independent of PI-3 kinase activation. To further investigate this conclusion, we studied the FcϵRI-dependent PLC-γ activation in PI-3 kinase-deficient BMMCs. Methods MMCs (WT, p85α −/− and p85β −/−) were sensitized with mouse monoclonal IgE anti-DNP, activated with DNP-HSA, PI-3 kinase activation (AKT phosphorylation and PIP3 production), and PLC-γ activation (PLC-γ1 and PLC-γ2 membrane translocation, phosphorylation, IP 3 formation and intracellular calcium) and degranulation were monitored. Results In WT BMMCs, following FcϵRI aggregation, PLC-γ and PI-3 kinase were activated in a manner similar to that observed in human MC. Wortmannin blocks PI-3 kinase but not PLC-γ activation in these cells. p85α −/− BMMCs presented a defective phosphorylation of AKT after FcϵRI aggregation, demonstrating a defect in PI-3 kinase activation. PLC-γ1 and PLC-γ2 were expressed at similar levels in the three cell types, and after FcϵRI aggregation, were translocated to the membrane and phosphorylated in a WT manner. Similarly, IP 3 production and intracellular calcium flux did not show major differences in the three types of BMMCs. Finally, although we were unable to detect a defect in degranulation in p85α and p85β deficient BMMCs, other data suggest that there may also be a PI-3 kinase dependent phase involved in FcϵRI-mediated degranulation. Conclusions Taken together, these data suggest that the PLC-γ1-dependent pathway of FcϵRI-dependent activation is independent of PI-3kinase.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
