Research Project
2187136
The intracellular D-3-phosphorylated phosphoinositides (3-PPI) include phosphatidylinositol 3-phosphate, PtdIns(3)P,phosphatidylinositol 3,4- bisphosphate, PtdIns(3,4)P2,and phosphatidylinositol 3,4,5-trisphosphate, PtdIns(3,4,5)P3. The 3-PPI are metabolic products of the action of phosphatidylinositol 3-kinase (PI 3-Kinase) on phosphatidylinositol phosphates. PI 3-Kinase physically associates with and is phosphorylated by activated growth factor receptors and oncogenes which manifest protein-tyrosine kinase activity. Mutational studies of growth factor receptors and oncogenes have shown that the associated PI 3-Kinase and its products PtdIns(3,4)P2 and PtdIns(3,4,5)P3 regulate cell growth and transformation. The 3-PPI are not physiological substrates for the PI- specific phospholipases C and so the intact lipids have been suggested as novel critical second messengers of growth signals. Very recently, the 3-PPI in vitro have been found to be potent and selective activators of PKC-delta, epsilon and nu, the PKC isoforms that mediate signalling downstream of certain mitogenic pathways. Additional biochemical studies are necessary to define the cellular targets of PtdIns(3,4)P2 and Ptdins(3,4,5)P3, the metabolic fate of these lipids, and their roles in the cell cycle. These studies would be facilitated if the 3-PPI were available from a commercial source. The overall objectives of this proposal are to develop synthetic approaches for 3-PPI and analogues, and to prepare and characterize these by physicochemical and spectrometric techniques. During Phase I, the feasibility of these approaches was tested and validated for the synthesis of PtdIns(3,4,5)P3, and the product characterized by analytical, physicochemical and spectrometric measurements. In Phase II, these approaches will be adapted and extended for the syntheses of PtdIns(3)P, Ptdins(3,4)P2, selected structural and stereo isomers analogues and congeners. PROPOSED COMMERCIAL APPLICATION: There is an unmet demand for 3-PPI and an immediate commercial potential as research biochemicals. In the longer term, there is a potential broader market for analogues and congeners in medical and biotechnology research. Further, the proposed synthetic methodology is appropriate technology for the preparation of the related inositol polyphosphates for which there is an immediate market.
