Recent insights in phosphatidylinositol signaling

Studies of phosphatidylinositol signaling pathways are entering a new phase in which molecular genetic techniques are providing powerful tools to dissect the functions of various metabolites and pathways. Studies with phospholipase C are most advanced and clearly indicate that phosphatidylinositol turnover is critical for vision in Drosophila and cell proliferation in various cultured cells. Expression of cDNA constructs and microinjection of PLC or antibodies against it clearly establish a role for PtdIns signaling distinct from its role in calcium mobilization and protein kinase C activation. The importance of inositol cyclic phosphates is also beginning to be realized from the study of cyclic hydrolase using similar techniques. Elucidation of the function of the 3-phosphate inositol phospholipid pathway awaits similar studies. The recent cDNA cloning of inositol monophosphatase ( Diehl et al., 1990 Diehl R.E. Whiting P. Potter J. Gee N. Ragan C.I. Linemeyer D. Schoepfer R. Bennett C. Dixon R.A.F. Cloning and expression of bovine brain inositol monophosphatase. J. Biol. Chem. 1990; 265: 5946-5949 Abstract Full Text PDF PubMed Google Scholar ), Ins(1,4,5)P3 3-kinase ( Choi et al., 1990 Choi K.Y. Kim H.K. Lee S.Y. Moon K.H. Sim S.S. Kim J.W. Chung H.K. Rhee S.G. Molecular cloning and expression of a complementary DNA for inositol 1,4,5-trisphosphate 3-kinase. Science. 1990; 248: 64-66 Crossref PubMed Scopus (116) Google Scholar ), and inositol polyphosphate 1-phosphatase ( York and Majerus, 1991 York J.D. Majerus P.W. The isolation and heterologous expression of a cDNA encoding inositol polyphosphate 1 phosphatase. in: Proc. Natl. Acad. Sci. USA. 1991 Google Scholar ) should provide tools to define further the cell biology of the phosphatidylinositol signaling pathway.