Type I Phosphatidylinositol-4-phosphate 5-Kinases Synthesize the Novel Lipids Phosphatidylinositol 3,5-Bisphosphate and Phosphatidylinositol 5-Phosphate*
- Kimberley F. Toliasद,
- Lucia E. Rameh‡§,
- Hisamitsu Ishihara‖,
- Yoshikazu Shibasaki‖,
- Jian Chen**,
- Glenn D. Prestwich**,
- Lewis C. Cantleyठand
- Christopher L. Carpenter‡‡
- From the ‡Division of Signal Transduction, Beth Israel Deaconess Medical Center, Departments of §Cell Biology and‡Medicine, Harvard Medical School, Boston, Massachusetts, the ‖Third Department of Internal Medicine, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113, Japan, and the**Department of Medicinal Chemistry, University of Utah, Salt Lake City, Utah 84112-5820
Abstract
Inositol phospholipids regulate a variety of cellular processes including proliferation, survival, vesicular trafficking, and cytoskeletal organization. Recently, two novel phosphoinositides, phosphatidylinositol-3,5-bisphosphate (PtdIns-3,5-P2) and phosphatidylinositol- 5-phosphate (PtdIns-5-P), have been shown to exist in cells. PtdIns-3,5-P2, which is regulated by osmotic stress, appears to be synthesized by phosphorylation of PtdIns-3-P at the D-5 position. No evidence yet exists for how PtdIns-5-P is produced in cells. Understanding the regulation of synthesis of these molecules will be important for identifying their function in cellular signaling. To determine the pathway by which PtdIns-3,5-P2 and Ptd-Ins-5-P might be synthesized, we tested the ability of the recently cloned type I PtdIns-4-P 5-kinases (PIP5Ks) α and β to phosphorylate PtdIns-3-P and PtdIns at the D-5 position of the inositol ring. We found that the type I PIP5Ks phosphorylate PtdIns-3-P to form PtdIns-3,5-P2. The identity of the PtdIns-3,5-P2 product was determined by anion exchange high performance liquid chromatography analysis and periodate treatment. PtdIns-3,4-P2 and PtdIns-3,4,5-P3 were also produced from PtdIns-3-P phosphorylation by both isoforms. When expressed in mammalian cells, PIP5K Iα and PIP5K Iβ differed in their ability to synthesize PtdIns-3,5-P2 relative to PtdIns-3,4-P2. We also found that the type I PIP5Ks phosphorylate PtdIns to produce PtdIns-5-P and phosphorylate PtdIns-3,4-P2 to produce PtdIns-3,4,5-P3. Our findings suggest that type I PIP5Ks synthesize the novel phospholipids PtdIns-3,5-P2 and PtdIns-5-P. The ability of PIP5Ks to produce multiple signaling molecules indicates that they may participate in a variety of cellular processes.
Footnotes
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↵* This work was supported by National Institutes of Health Grants GM54389 (to C. L. C.), GM36624 (to L. C. C.), and NS 29632 (to G. D. P.).The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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↵¶ To whom correspondence should be addressed: Div. of Signal Transduction, Harvard Institute of Medicine, 1007, 330 Brookline Ave., Boston, MA 02115. Tel.: 617-667-0941; Fax: 617-667-0957; E-mail:ktolias{at}bidmc.harvard.edu.
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↵1 The abbreviations used are: PtdIns-4,5-P2, phosphatidylinositol 4,5-bisphosphate; PtdIns, phosphatidylinositol; PtdIns-3-P, phosphatidylinositol 3-phosphate; PtdIns-4-P, phosphatidylinositol 4-phosphate; PtdIns-5-P, phosphatidylinositol 5-phosphate; PtdIns-3,4-P2, phosphatidylinositol 3,4-bisphosphate; PtdIns-3,5-P2, phosphatidylinositol 3,5-bisphosphate; PtdIns-3,4,5-P3 and PtdInsP3, phosphatidylinositol 3,4,5-triphosphate; Ins-1,3,4-P3, inositol 1,3,4-triphosphate; Ins-1,3,5-P3, inositol 1,3,5-triphosphate; Ins-1,4,5-P3, inositol 1,4,5-triphosphate; GroPIns, glycerophosphorylinositol; type I PIP5K, type I phosphatidylinositol-4-phosphate 5-kinase; type II PIPK, type II phosphatidylinositol phosphate kinase; PI3K, phosphoinositide 3-kinase; HPLC, high performance liquid chromatography.
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↵2 J. Chen, L. Feng, and G. D. Prestwich, manuscript in preparation.
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- Received March 31, 1998.
- The American Society for Biochemistry and Molecular Biology, Inc.
