Evidence that 3′-phosphorylated polyphosphoinositides are generated at the nuclear surface:: use of immunostaining technique with monoclonal antibodies specific for PI 3,4-P2

Phosphatidylinositol (PI) 3,4-P-2 is a phosphoinositide that has been shown to be important for signal transduction in growth factor stimulation, We have produced monoclonal antibodies specific for PI 3,4-P-2, which were able to detect PI 3,4-P-2 generated in 293T cells treated with H2O2, or in MKN45/ BD110 cells expressing activated PI 3-kinase in immunostaining, Prolonged treatment with 0.05% Tween 20 resulted in detection of staining not only at the plasma membrane, but also at the nuclear surface, indicating that 3'-phosphorylated phosphoinositides can be generated and function in the nucleus. (C) 2000 Federation of European Biochemical Societies.