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Matulonis UA, Wulf GM, Barry WT, Birrer M, Westin SN, Farooq S, Bell-McGuinn KM, Obermayer E, Whalen C, Spagnoletti T, Luo W, Liu H, Hok RC, Aghajanian C, Solit DB, Mills GB, Taylor BS, Won H, Berger MF, Palakurthi S, Liu J, Cantley LC, Winer E. Phase I dose escalation study of the PI3kinase pathway inhibitor BKM120 and the oral poly (ADP ribose) polymerase (PARP) inhibitor olaparib for the treatment of high-grade serous ovarian and breast cancer. Ann Oncol 2017; 28:512-518. [PMID: 27993796 PMCID: PMC5834157 DOI: 10.1093/annonc/mdw672] [Citation(s) in RCA: 145] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Background Based upon preclinical synergy in murine models, we carried out a phase I trial to determine the maximum tolerated dose (MTD), toxicities, pharmacokinetics, and biomarkers of response for the combination of BKM120, a PI3K inhibitor, and olaparib, a PARP inhibitor. Patients and methods Olaparib was administered twice daily (tablet formulation) and BKM120 daily on a 28-day cycle, both orally. A 3 + 3 dose-escalation design was employed with the primary objective of defining the combination MTD, and secondary objectives were to define toxicities, activity, and pharmacokinetic profiles. Eligibility included recurrent breast (BC) or ovarian cancer (OC); dose-expansion cohorts at the MTD were enrolled for each cancer. Results In total, 69 of 70 patients enrolled received study treatment; one patient never received study treatment because of ineligibility. Twenty-four patients had BC; 46 patients had OC. Thirty-five patients had a germline BRCA mutation (gBRCAm). Two DLTs (grade 3 transaminitis and hyperglycemia) were observed at DL0 (BKM120 60 mg/olaparib and 100 mg b.i.d.). The MTD was determined to be BKM120 50 mg q.d. and olaparib 300 mg b.i.d. (DL8). Additional DLTs included grade 3 depression and transaminitis, occurring early in cycle 2 (DL7). Anticancer activity was observed in BC and OC and in gBRCAm and gBRCA wild-type (gBRCAwt) patients. Conclusions BKM120 and olaparib can be co-administered, but the combination requires attenuation of the BKM120 dose. Clinical benefit was observed in both gBRCAm and gBRCAwt pts. Randomized phase II studies will be needed to further define the efficacy of PI3K/PARP-inhibitor combinations as compared with a PARP inhibitor alone.
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Affiliation(s)
- U. A. Matulonis
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston
| | - G. M. Wulf
- Division of Hematology and Oncology, Beth Israel Deaconess Medical Center, Boston
| | - W. T. Barry
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston
| | - M. Birrer
- Department of Hematology and Oncology, Massachusetts General Hospital, Boston
| | - S. N. Westin
- Department of Gynecologic Oncology, MD Anderson Cancer Center, Houston
| | - S. Farooq
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston
| | | | - E. Obermayer
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston
| | - C. Whalen
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston
| | - T. Spagnoletti
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston
| | - W. Luo
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston
| | - H. Liu
- Division of Hematology and Oncology, Beth Israel Deaconess Medical Center, Boston
| | - R. C. Hok
- Division of Hematology and Oncology, Beth Israel Deaconess Medical Center, Boston
| | | | - D. B. Solit
- Memorial Sloan Kettering Cancer Center, New York
| | - G. B. Mills
- Department of Systems Biology, Division of Basic Science Research, The University of Texas MD Anderson Cancer Center, Houston
| | - B. S. Taylor
- Memorial Sloan Kettering Cancer Center, New York
| | - H. Won
- Memorial Sloan Kettering Cancer Center, New York
| | - M. F. Berger
- Memorial Sloan Kettering Cancer Center, New York
| | - S. Palakurthi
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston
| | - J. Liu
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston
| | | | - E. Winer
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston
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Locasale JW, Melman T, Song SS, Yang X, Swanson KD, Cantley LC, Asara JM, Wong ET, Adams S, Braidy N, Teo C, Guillemin G, Philippe M, Carole C, David T, Eric G, Isabelle NM, de Paula Andre M, Marylin B, Olivier C, L'Houcine O, Dominique FB, Leukel P, Seliger C, Vollmann A, Jachnik B, Bogdahn U, Hau P, Liu X, Kumar VS, McPherson CM, Chow L, Kendler A, Dasgupta B, Piya S, White E, Klein S, Jiang H, Lang F, Alfred Yung WK, Gomez-Manzano C, Fueyo J, Vartanian A, Guha A, Fenton KE, Abdelwahab M, Scheck AC, Guo D, Reinitz F, Youssef M, Hong C, Nathanson D, Akhavan D, Kuga D, Amzajerdi AN, Soto H, Zhu S, Babic I, Iwanami A, Tanaka K, Gini B, DeJesus J, Lisiero DD, Huang T, Prins R, Wen P, Robbins HI, Prados M, DeAngelis L, Mellinghoff I, Mehta M, James CD, Chakravarti A, Cloughesy T, Tontonoz P, Mischel P, Phillips J, Mukherjee J, Cowdrey C, Wiencke J, Pieper RO, Bachoo R, Marin-Valencia I, Cho S, Rakheja D, Hatanpaa K, Mashimo T, Vemireddy V, Kapur P, Good L, Sun X, Pascual J, Takahashi M, Togao O, Raisanen J, Maher EA, DeBerardinis R, Malloy C, Maher EA, Bachoo R, Marin-Valencia I, Hatanpaa K, Choi C, Mashimo T, Raisanen J, Mathews D, Pascual J, Madden C, Mickey B, Malloy C, DeBerardinis R, Mukherjee J, Zheng S, Phillips J, Cowdrey C, Ronen S, Wiencke J, Pieper RO, Park I, Jalbert LE, Ito M, Ozawa T, James CD, Phillips JJ, Vigneron DB, Pieper RO, Ronen SM, Nelson SJ. METABOLIC PATHWAYS. Neuro Oncol 2011; 13:iii69-iii72. [PMCID: PMC3199168 DOI: 10.1093/neuonc/nor153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/14/2023] Open
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3
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Asara JM, Schweitzer MH, Cantley LC, Cottrell JS. Response to Comment on "Protein Sequences from Mastodon and Tyrannosaurus rex Revealed by Mass Spectrometry". Science 2008. [DOI: 10.1126/science.1157829] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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4
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Cantley LC. Growth Factors Bind Receptor Tyrosine Kinases to Stimulate Cell Survival, Cell Division, Cell Growth, and Cytoskeletal Rearrangement. Sci Signal 2003. [DOI: 10.1126/stke.2122003tr8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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5
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Manning BD, Cantley LC. United at last: the tuberous sclerosis complex gene products connect the phosphoinositide 3-kinase/Akt pathway to mammalian target of rapamycin (mTOR) signalling. Biochem Soc Trans 2003; 31:573-8. [PMID: 12773158 DOI: 10.1042/bst0310573] [Citation(s) in RCA: 157] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The molecular interplay between the phosphoinositide 3-kinase (PI3K) pathway and mammalian target of rapamycin (mTOR) signalling in the control of cell growth and proliferation has been the subject of much interest and debate amongst cell biologists. A recent escalation of research in this area has come from the discovery of the tuberous sclerosis complex gene products, tuberin and hamartin, as central regulators of mTOR activation. The PI3K effector Akt/protein kinase B has been found to directly phosphorylate tuberin and is thereby thought to activate mTOR through inhibition of the tuberin-hamartin complex. The many recent studies aimed at defining the molecular nature of this revamped PI3K/Akt/mTOR pathway are reviewed here. The collective data discussed have laid the groundwork for important new insights into the many cancers caused by aberrant PI3K activation and the clinically challenging tuberous sclerosis complex disease and have suggested a possible means of treatment for both.
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Affiliation(s)
- B D Manning
- Department of Cell Biology, Harvard Medical School, Division of Signal Transduction, Beth Israel Deaconess Medical Center, 4 Blackfan Circle, Boston, MA 02115, USA
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Abstract
In vertebrates, the development and integrity of the skeleton requires hydroxyapatite (HA) deposition by osteoblasts. HA deposition is also a marker of, or a participant in, processes as diverse as cancer and atherosclerosis. At present, sites of osteoblastic activity can only be imaged in vivo using gamma-emitting radioisotopes. The scan times required are long, and the resultant radioscintigraphic images suffer from relatively low resolution. We have synthesized a near-infrared (NIR) fluorescent bisphosphonate derivative that exhibits rapid and specific binding to HA in vitro and in vivo. We demonstrate NIR light-based detection of osteoblastic activity in the living animal, and discuss how this technology can be used to study skeletal development, osteoblastic metastasis, coronary atherosclerosis, and other human diseases.
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Affiliation(s)
- A Zaheer
- Department of Radiology, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
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8
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Singh VP, Saluja AK, Bhagat L, van Acker GJ, Song AM, Soltoff SP, Cantley LC, Steer ML. Phosphatidylinositol 3-kinase-dependent activation of trypsinogen modulates the severity of acute pancreatitis. J Clin Invest 2001; 108:1387-95. [PMID: 11696584 PMCID: PMC209439 DOI: 10.1172/jci12874] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2001] [Accepted: 09/10/2001] [Indexed: 12/11/2022] Open
Abstract
Intra-acinar cell activation of digestive enzyme zymogens including trypsinogen is generally believed to be an early and critical event in acute pancreatitis. We have found that the phosphatidylinositol 3-kinase inhibitor wortmannin can reduce the intrapancreatic activation of trypsinogen that occurs during two dissimilar experimental models of rodent acute pancreatitis, secretagogue- and duct injection-induced pancreatitis. The severity of both models was also reduced by wortmannin administration. In contrast, the NF-kappa B activation that occurs during the early stages of secretagogue-induced pancreatitis is not altered by administration of wortmannin. Ex vivo, caerulein-induced trypsinogen activation is inhibited by wortmannin and LY294002. However, the cytoskeletal changes induced by caerulein were not affected by wortmannin. Concentrations of caerulein that induced ex vivo trypsinogen activation do not significantly increase phosphatidylinositol-3,4-bisphosphate or phosphatidylinositol 3,4,5-trisphosphate levels or induce phosphorylation of Akt/PKB, suggesting that class I phosphatidylinositol 3-kinases are not involved. The concentration of wortmannin that inhibits trypsinogen activation causes a 75% decrease in phosphatidylinositol 3-phosphate, which is implicated in vesicle trafficking and fusion. We conclude that a wortmannin-inhibitable phosphatidylinositol 3-kinase is necessary for intrapancreatic activation of trypsinogen and regulating the severity of acute pancreatitis. Our observations suggest that phosphatidylinositol 3-kinase inhibition might be of benefit in preventing acute pancreatitis.
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Affiliation(s)
- V P Singh
- Department of Surgery, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts 02215, USA
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9
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Vieira OV, Botelho RJ, Rameh L, Brachmann SM, Matsuo T, Davidson HW, Schreiber A, Backer JM, Cantley LC, Grinstein S. Distinct roles of class I and class III phosphatidylinositol 3-kinases in phagosome formation and maturation. J Cell Biol 2001; 155:19-25. [PMID: 11581283 PMCID: PMC2150784 DOI: 10.1083/jcb.200107069] [Citation(s) in RCA: 390] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Phagosomes acquire their microbicidal properties by fusion with lysosomes. Products of phosphatidylinositol 3-kinase (PI 3-kinase) are required for phagosome formation, but their role in maturation is unknown. Using chimeric fluorescent proteins encoding tandem FYVE domains, we found that phosphatidylinositol 3-phosphate (PI[3]P) accumulates greatly but transiently on the phagosomal membrane. Unlike the 3'-phosphoinositides generated by class I PI 3-kinases which are evident in the nascent phagosomal cup, PI(3)P is only detectable after the phagosome has sealed. The class III PI 3-kinase VPS34 was found to be responsible for PI(3)P synthesis and essential for phagolysosome formation. In contrast, selective ablation of class I PI 3-kinase revealed that optimal phagocytosis, but not maturation, requires this type of enzyme. These results highlight the differential functional role of the two families of kinases, and raise the possibility that PI(3)P production by VPS34 may be targeted during the maturation arrest induced by some intracellular parasites.
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Affiliation(s)
- O V Vieira
- Cell Biology Program, Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada
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10
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Kanai F, Liu H, Field SJ, Akbary H, Matsuo T, Brown GE, Cantley LC, Yaffe MB. The PX domains of p47phox and p40phox bind to lipid products of PI(3)K. Nat Cell Biol 2001; 3:675-8. [PMID: 11433300 DOI: 10.1038/35083070] [Citation(s) in RCA: 478] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
PX domains are found in a variety of proteins that associate with cell membranes, but their molecular function has remained obscure. We show here that the PX domains in p47phox and p40phox subunits of the phagocyte NADPH oxidase bind to phosphatidylinositol-3,4-bisphosphate (PtdIns(3,4)P(2)) and phosphatidylinositol-3-phosphate (PtdIns(3)P), respectively. We also show that an Arg-to-Gln mutation in the PX domain of p47phox, which is found in patients with chronic granulomatous disease, eliminates phosphoinositide binding, as does the analogous mutation in the PX domain of p40phox. The PX domain of p40phox localizes specifically to PtdIns(3)P-enriched early endosomes, and this localization is disrupted by inhibition of phosphoinositide-3-OH kinase (PI(3)K) or by the Arg-to-Gln point mutation. These findings provide a molecular foundation to understand the role of PI(3)K in regulating neutrophil function and inflammation, and to identify PX domains as specific phosphoinositide-binding modules involved in signal transduction events in eukaryotic cells.
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Affiliation(s)
- F Kanai
- Center for Cancer Research and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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11
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Abstract
The number of known proteases is increasing at a tremendous rate as a consequence of genome sequencing projects. Although one can guess at the functions of these novel enzymes by considering sequence homology to known proteases, there is a need for new tools to rapidly provide functional information on large numbers of proteins. We describe a method for determining the cleavage site specificity of proteolytic enzymes that involves pooled sequencing of peptide library mixtures. The method was used to determine cleavage site motifs for six enzymes in the matrix metalloprotease (MMP) family. The results were validated by comparison with previous literature and by analyzing the cleavage of individually synthesized peptide substrates. The library data led us to identify the proteoglycan neurocan as a novel MMP-2 substrate. Our results indicate that a small set of libraries can be used to quickly profile an expanding protease family, providing information applicable to the design of inhibitors and to the identification of protein substrates.
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Affiliation(s)
- B E Turk
- Department of Medicine, Beth Israel Deaconess Medical Center, Department of Cell Biology, Harvard Medical School, 330 Brookline Avenue, Boston, MA 02215, USA
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12
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Sweeney C, Fambrough D, Huard C, Diamonti AJ, Lander ES, Cantley LC, Carraway KL. Growth factor-specific signaling pathway stimulation and gene expression mediated by ErbB receptors. J Biol Chem 2001; 276:22685-98. [PMID: 11297548 DOI: 10.1074/jbc.m100602200] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The mechanisms by which receptor tyrosine kinases (RTKs) utilize intracellular signaling pathways to direct gene expression and cellular response remain unclear. A current question is whether different RTKs within a single cell target similar or different sets of genes. In this study we have used the ErbB receptor network to explore the relationship between RTK activation and gene expression. We profiled growth factor-stimulated signaling pathway usage and broad gene expression patterns in two human mammary tumor cell lines expressing different complements of ErbB receptors. Although the growth factors epidermal growth factor (EGF) and neuregulin (NRG) 1 similarly stimulated Erk1/2 in MDA-MB-361 cells, EGF acting through an EGF receptor/ErbB2 heterodimer preferentially stimulated protein kinase C, and NRG1beta acting through an ErbB2/ErbB3 heterodimer preferentially stimulated Akt. The two growth factors regulated partially overlapping yet distinct sets of genes in these cells. In MDA-MB-453 cells, NRG1beta acting through an ErbB2/ErbB3 heterodimer stimulated prolonged signaling of all pathways examined relative to NRG2beta acting through the same heterodimeric receptor species. Surprisingly, NRG1beta and NRG2beta also regulated partially overlapping but distinct sets of genes in these cells. These results demonstrate that the activation of different RTKs, or activation of the same RTKs with different ligands, can lead to distinct profiles of gene regulation within a single cell type. Our observations also suggest that the identity and kinetics of signaling pathway usage by RTKs may play a role in the selection of regulated genes.
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Affiliation(s)
- C Sweeney
- Department of Cell Biology, Harvard Medical School and Division of Signal Transduction, Beth Israel Deaconess Medical Center, Boston, Massachusetts 02215, USA.
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13
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Affiliation(s)
- L C Cantley
- Department of Cell Biology, Harvard Medical School and Division of Signal Transduction, Beth Israel Deaconess Medical Center, Boston, MA 02115, USA.
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14
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Karuman P, Gozani O, Odze RD, Zhou XC, Zhu H, Shaw R, Brien TP, Bozzuto CD, Ooi D, Cantley LC, Yuan J. The Peutz-Jegher gene product LKB1 is a mediator of p53-dependent cell death. Mol Cell 2001; 7:1307-19. [PMID: 11430832 DOI: 10.1016/s1097-2765(01)00258-1] [Citation(s) in RCA: 242] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Here, we investigate the mechanism and function of LKB1, a Ser/Thr kinase mutated in Peutz-Jegher syndrome (PJS). We demonstrate that LKB1 physically associates with p53 and regulates specific p53-dependent apoptosis pathways. LKB1 protein is present in both the cytoplasm and nucleus of living cells and translocates to mitochondria during apoptosis. In vivo, LKB1 is highly upregulated in pyknotic intestinal epithelial cells. In contrast, polyps arising in Peutz-Jegher patients are devoid of LKB1 staining and have reduced numbers of apoptotic cells. We propose that a deficiency in apoptosis is a key factor in the formation of multiple benign intestinal polyps in PJS patients, and possibly for the subsequent development of malignant tumors in these patients.
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Affiliation(s)
- P Karuman
- Department of Cell Biology, Harvard Medical School, 02115, Boston, MA, USA
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15
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Bertenshaw GP, Turk BE, Hubbard SJ, Matters GL, Bylander JE, Crisman JM, Cantley LC, Bond JS. Marked differences between metalloproteases meprin A and B in substrate and peptide bond specificity. J Biol Chem 2001; 276:13248-55. [PMID: 11278902 DOI: 10.1074/jbc.m011414200] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Meprin A and B are highly regulated, secreted, and cell-surface metalloendopeptidases that are abundantly expressed in the kidney and intestine. Meprin oligomers consist of evolutionarily related alpha and/or beta subunits. The work herein was carried out to identify bioactive peptides and proteins that are susceptible to hydrolysis by mouse meprins and kinetically characterize the hydrolysis. Gastrin-releasing peptide fragment 14-27 and gastrin 17, regulatory molecules of the gastrointestinal tract, were found to be the best peptide substrates for meprin A and B, respectively. Peptide libraries and a variety of naturally occurring peptides revealed that the meprin beta subunit has a clear preference for acidic amino acids in the P1 and P1' sites of substrates. The meprin alpha subunit selected for small (e.g. serine, alanine) or hydrophobic (e.g. phenylalanine) residues in the P1 and P1' sites, and proline was the most preferred amino acid at the P2' position. Thus, although the meprin alpha and beta subunits share 55% amino acid identity within the protease domain and are normally localized at the same tissue cell surfaces, they have very different substrate and peptide bond specificities indicating different functions. Homology models of the mouse meprin alpha and beta protease domains, based on the astacin crystal structure, revealed active site differences that can account for the marked differences in substrate specificity of the two subunits.
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Affiliation(s)
- G P Bertenshaw
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033, USA
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Yaffe MB, Leparc GG, Lai J, Obata T, Volinia S, Cantley LC. A motif-based profile scanning approach for genome-wide prediction of signaling pathways. Nat Biotechnol 2001; 19:348-53. [PMID: 11283593 DOI: 10.1038/86737] [Citation(s) in RCA: 415] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The rapid increase in genomic information requires new techniques to infer protein function and predict protein-protein interactions. Bioinformatics identifies modular signaling domains within protein sequences with a high degree of accuracy. In contrast, little success has been achieved in predicting short linear sequence motifs within proteins targeted by these domains to form complex signaling networks. Here we describe a peptide library-based searching algorithm, accessible over the World Wide Web, that identifies sequence motifs likely to bind to specific protein domains such as 14-3-3, SH2, and SH3 domains, or likely to be phosphorylated by specific protein kinases such as Src and AKT. Predictions from database searches for proteins containing motifs matching two different domains in a common signaling pathway provides a much higher success rate. This technology facilitates prediction of cell signaling networks within proteomes, and could aid in the identification of drug targets for the treatment of human diseases.
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Affiliation(s)
- M B Yaffe
- Division of Signal Transduction, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Institutes of Medicine, 10th Floor, 330 Brookline Ave. Boston, MA 02215 USA.
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Affiliation(s)
- M B Yaffe
- Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts 02215, USA
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18
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Kanai F, Marignani PA, Sarbassova D, Yagi R, Hall RA, Donowitz M, Hisaminato A, Fujiwara T, Ito Y, Cantley LC, Yaffe MB. TAZ: a novel transcriptional co-activator regulated by interactions with 14-3-3 and PDZ domain proteins. EMBO J 2000; 19:6778-91. [PMID: 11118213 PMCID: PMC305881 DOI: 10.1093/emboj/19.24.6778] [Citation(s) in RCA: 570] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The highly conserved and ubiquitously expressed 14-3-3 proteins regulate differentiation, cell cycle progression and apoptosis by binding intracellular phosphoproteins involved in signal transduction. By screening in vitro translated cDNA pools for the ability to bind 14-3-3, we identified a novel transcriptional co-activator, TAZ (transcriptional co-activator with PDZ-binding motif) as a 14-3-3-binding molecule. TAZ shares homology with Yes-associated protein (YAP), contains a WW domain and functions as a transcriptional co-activator by binding to the PPXY motif present on transcription factors. 14-3-3 binding requires TAZ phosphorylation on a single serine residue, resulting in the inhibition of TAZ transcriptional co-activation through 14-3-3-mediated nuclear export. The C-terminus of TAZ contains a highly conserved PDZ-binding motif that localizes TAZ into discrete nuclear foci and is essential for TAZ-stimulated gene transcription. TAZ uses this same motif to bind the PDZ domain-containing protein NHERF-2, a molecule that tethers plasma membrane ion channels and receptors to cytoskeletal actin. TAZ may link events at the plasma membrane and cytoskeleton to nuclear transcription in a manner that can be regulated by 14-3-3.
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Affiliation(s)
- F Kanai
- Division of Signal Transduction, Department of Medicine and Department of Surgery, Beth Israel Deaconess Medical Center, Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
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Obata T, Yaffe MB, Leparc GG, Piro ET, Maegawa H, Kashiwagi A, Kikkawa R, Cantley LC. Peptide and protein library screening defines optimal substrate motifs for AKT/PKB. J Biol Chem 2000; 275:36108-15. [PMID: 10945990 DOI: 10.1074/jbc.m005497200] [Citation(s) in RCA: 320] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
AKT was originally identified as a proto-oncogene with a pleckstrin homology and Ser/Thr protein kinase domains. Recent studies revealed that AKT regulates a variety of cellular functions including cell survival, cell growth, cell differentiation, cell cycle progression, transcription, translation, and cellular metabolism. To clarify the substrate specificity of AKT, we have used an oriented peptide library approach to determine optimal amino acids at positions N-terminal and C-terminal to the site of phosphorylation. The predicted optimal peptide substrate (Arg-Lys-Arg-Xaa-Arg-Thr-Tyr-Ser*-Phe-Gly where Ser* is the phosphorylation site) has similarities to but is distinct from optimal substrates that we previously defined for related basophilic protein kinases such as protein kinase A, Ser/Arg-rich kinases, and protein kinase C family members. The positions most important for high V(max)/K(m) ratio were Arg-3>Arg-5>Arg-7. The substrate specificity of AKT was further investigated by screening a lambdaGEX phage HeLa cell cDNA expression library. All of the substrates identified by this procedure contained Arg-Xaa-Arg-Xaa-Xaa-(Ser/Thr) motifs and were in close agreement with the motif identified by peptide library screening. The results of this study should help in prediction of likely AKT substrates from primary sequences.
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Affiliation(s)
- T Obata
- Departments of Medicine and Surgery, Beth Israel Deaconess Medical Center, Boston, Massachusetts 02215, USA
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Fruman DA, Mauvais-Jarvis F, Pollard DA, Yballe CM, Brazil D, Bronson RT, Kahn CR, Cantley LC. Hypoglycaemia, liver necrosis and perinatal death in mice lacking all isoforms of phosphoinositide 3-kinase p85 alpha. Nat Genet 2000; 26:379-82. [PMID: 11062485 DOI: 10.1038/81715] [Citation(s) in RCA: 217] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Phosphoinositide 3-kinases produce 3'-phosphorylated phosphoinositides that act as second messengers to recruit other signalling proteins to the membrane. Pi3ks are activated by many extracellular stimuli and have been implicated in a variety of cellular responses. The Pi3k gene family is complex and the physiological roles of different classes and isoforms are not clear. The gene Pik3r1 encodes three proteins (p85 alpha, p55 alpha and p50 alpha) that serve as regulatory subunits of class IA Pi3ks (ref. 2). Mice lacking only the p85 alpha isoform are viable but display hypoglycaemia and increased insulin sensitivity correlating with upregulation of the p55 alpha and p50 alpha variants. Here we report that loss of all protein products of Pik3r1 results in perinatal lethality. We observed, among other abnormalities, extensive hepatocyte necrosis and chylous ascites. We also noted enlarged skeletal muscle fibres, brown fat necrosis and calcification of cardiac tissue. In liver and muscle, loss of the major regulatory isoform caused a great decrease in expression and activity of class IA Pi3k catalytic subunits; nevertheless, homozygous mice still displayed hypoglycaemia, lower insulin levels and increased glucose tolerance. Our findings reveal that p55 alpha and/or p50 alpha are required for survival, but not for development of hypoglycaemia, in mice lacking p85 alpha.
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MESH Headings
- Abnormalities, Multiple/genetics
- Adipose Tissue, Brown/pathology
- Animals
- Animals, Outbred Strains
- Calcinosis/genetics
- Cardiomyopathies/genetics
- Catalysis
- Chylous Ascites/genetics
- Crosses, Genetic
- Dimerization
- Enzyme Induction
- Female
- Genes
- Genes, Lethal
- Genotype
- Germ-Free Life
- Glucose/metabolism
- Glucose/pharmacology
- Hypertrophy
- Hypoglycemia/genetics
- Insulin/pharmacology
- Liver/pathology
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Inbred ICR
- Mice, Knockout
- Muscle Fibers, Skeletal/pathology
- Necrosis
- Phosphatidylinositol 3-Kinases/deficiency
- Phosphatidylinositol 3-Kinases/genetics
- Phosphatidylinositol 3-Kinases/physiology
- Phosphorylation
- Protein Isoforms/deficiency
- Protein Isoforms/genetics
- Protein Isoforms/physiology
- Protein Processing, Post-Translational/genetics
- Protein Subunits
- Second Messenger Systems/genetics
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Affiliation(s)
- D A Fruman
- Division of Signal Transduction, Beth Israel Deaconess Medical Center Boston, Massachusetts, USA
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21
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Nishikawa K, Sawasdikosol S, Fruman DA, Lai J, Songyang Z, Burakoff SJ, Yaffe MB, Cantley LC. A peptide library approach identifies a specific inhibitor for the ZAP-70 protein tyrosine kinase. Mol Cell 2000; 6:969-74. [PMID: 11090635 DOI: 10.1016/s1097-2765(05)00085-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We utilized a novel peptide library approach to identify specific inhibitors of ZAP-70, a protein Tyr kinase involved in T cell activation. By screening more than 6 billion peptides oriented by a common Tyr residue for their ability to bind to ZAP-70, we determined a consensus optimal peptide. A Phe-for-Tyr substituted version of the peptide inhibited ZAP-70 protein Tyr kinase activity by competing with protein substrates (K(I) of 2 microM). The related protein Tyr kinases, Lck and Syk, were not significantly inhibited by the peptide. When introduced into intact T cells, the peptide blocked signaling downstream of ZAP-70, including ZAP-70-dependent gene induction, without affecting upstream Tyr phosphorylation. Thus, screening Tyr-oriented peptide libraries can identify selective peptide inhibitors of protein Tyr kinases.
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Affiliation(s)
- K Nishikawa
- Division of Signal Transduction, Beth Israel Deaconess Medical Center, Boston, Massachusetts 02115, USA
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22
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Frangioni JV, LaRiccia LM, Cantley LC, Montminy MR. Minimal activators that bind to the KIX domain of p300/CBP identified by phage display screening. Nat Biotechnol 2000; 18:1080-5. [PMID: 11017047 DOI: 10.1038/80280] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Human gene therapy approaches involving transcription factors often rely on artificial activation domains for transcriptional activation. These domains are often large (e.g., 80 amino acids for VP16), recruit multiple co-activation complexes at once, and offer no fine control over the level of transcription. In an attempt to understand the sequence and structural requirements of a minimal mammalian activator, we employed a molecular diversity approach with a peptide phage display library composed of random eight-amino acid peptides. Using the KIX domain of the mammalian co-activators p300 and CBP as target, we discovered a family of synthetic binding peptides. These peptides share significant homology with natural KIX domain ligands, and are shown to bind an overlapping, yet distinct, surface of p300/CREB-binding protein (CBP). When fused to a heterologous DNA binding domain, these synthetic peptides function as titratable, modular, and potent transcriptional activators in living cells through specific recruitment of p300/CBP, with the level of transcriptional activation proportional to the affinity of the synthetic peptide for the KIX domain. Taken together, our data demonstrate that a molecular diversity approach can be used to discover minimal, co-activator domain-specific synthetic activators, and that transcriptional activation can be modulated as desired at the level of co-activator recruitment.
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Affiliation(s)
- J V Frangioni
- The Division of Hematology/Oncology, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
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23
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O'Neill T, Dwyer AJ, Ziv Y, Chan DW, Lees-Miller SP, Abraham RH, Lai JH, Hill D, Shiloh Y, Cantley LC, Rathbun GA. Utilization of oriented peptide libraries to identify substrate motifs selected by ATM. J Biol Chem 2000; 275:22719-27. [PMID: 10801797 DOI: 10.1074/jbc.m001002200] [Citation(s) in RCA: 136] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The ataxia telangiectasia mutated (ATM) gene encodes a serine/threonine protein kinase that plays a critical role in genomic surveillance and development. Here, we use a peptide library approach to define the in vitro substrate specificity of ATM kinase activity. The peptide library analysis identified an optimal sequence with a central core motif of LSQE that is preferentially phosphorylated by ATM. The contributions of the amino acids surrounding serine in the LSQE motif were assessed by utilizing specific peptide libraries or individual peptide substrates. All amino acids comprising the LSQE sequence were critical for maximum peptide substrate suitability for ATM. The DNA-dependent protein kinase (DNA-PK), a Ser/Thr kinase related to ATM and important in DNA repair, was compared with ATM in terms of peptide substrate selectivity. DNA-PK was found to be unique in its preference of neighboring amino acids to the phosphorylated serine. Peptide library analyses defined a preferred amino acid motif for ATM that permits clear distinctions between ATM and DNA-PK kinase activity. Data base searches using the library-derived ATM sequence identified previously characterized substrates of ATM, as well as novel candidate substrate targets that may function downstream in ATM-directed signaling pathways.
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Affiliation(s)
- T O'Neill
- Center for Blood Research, Department of Pediatrics, Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
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24
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Abstract
The epidermal growth factor (EGF)-like family of growth factors elicits cellular responses by stimulating the dimerization, autophosphorylation, and tyrosine kinase activities of the ErbB family of receptor tyrosine kinases. Although several different EGF-like ligands are capable of binding to a single ErbB family member, it is generally thought that the biological and biochemical responses of a single receptor dimer to different ligands are indistinguishable. To test whether an ErbB receptor dimer is capable of discriminating among ligands we have examined the effect of four EGF-like growth factors on signaling through the ErbB4 receptor homodimer in CEM/HER4 cells, a transfected human T cell line ectopically expressing ErbB4 in an ErbB-null background. Despite stimulating similar levels of gross receptor tyrosine phosphorylation, the EGF-like growth factors betacellulin, neuregulin-1beta, neuregulin-2beta, and neuregulin-3 exhibited different biological potencies in a cellular growth assay. Moreover, the different ligands induced different patterns of recruitment of intracellular signaling proteins to the activated receptor and induced differential usage of intracellular kinase signaling cascades. Finally, two-dimensional phosphopeptide mapping of ligand-stimulated ErbB4 revealed that the different growth factors induce different patterns of receptor tyrosine phosphorylation. These results indicate that ErbB4 activation by growth factors is not generic and suggest that individual ErbB receptors can discriminate between different EGF-like ligands within the context of a single receptor dimer. More generally, our observations significantly modify our understanding of signaling through receptor tyrosine kinases and point to a number of possible models for ligand-mediated signal diversification.
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Affiliation(s)
- C Sweeney
- Department of Cell Biology, Harvard Medical School and Division of Signal Transduction, Beth Israel Deaconess Medical Center, Boston, Massachusetts 02215, USA
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25
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Satterthwaite AB, Willis F, Kanchanastit P, Fruman D, Cantley LC, Helgason CD, Humphries RK, Lowell CA, Simon M, Leitges M, Tarakhovsky A, Tedder TF, Lesche R, Wu H, Witte ON. A sensitized genetic system for the analysis of murine B lymphocyte signal transduction pathways dependent on Bruton's tyrosine kinase. Proc Natl Acad Sci U S A 2000; 97:6687-92. [PMID: 10829070 PMCID: PMC18703 DOI: 10.1073/pnas.110146697] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Modifier screens have been powerful genetic tools to define signaling pathways in lower organisms. The identification of modifier loci in mice has begun to allow a similar dissection of mammalian signaling pathways. Transgenic mice (Btk(lo)) expressing 25% of endogenous levels of Bruton's tyrosine kinase (Btk) have B cell functional responses between those of wild-type and Btk(-/-) mice. We asked whether reduced dosage or complete deficiency of genes previously implicated as Btk regulators would modify the Btk(lo) phenotype. We used two independent assays of Btk-dependent B cell function. Proliferative response to B cell antigen receptor cross-linking in vitro was chosen as an example of a relatively simple, well-defined signaling system. In vivo response to type II T-independent antigens (TI-II) measures complex interactions among multiple cell types over time and may identify additional Btk pathways. All modifiers identified differentially affected these two assays, indicating that Btk mediates these processes via distinct mechanisms. Loss of Lyn, PTEN (phosphatase and tensin homolog), or SH2-containing inositol phosphatase suppressed the Btk(lo) phenotype in vitro but not in vivo, whereas CD19 and the p85alpha form of phosphoinositide 3-kinase behaved as Btk(lo) enhancers in vivo but not in vitro. Effects of Lyn, PTEN, or p85alpha haploinsufficiency were observed. Haploinsufficiency or complete deficiency of protein kinase C beta, Fyn, CD22, Galphaq, or Galpha11 had no detectable effect on the function of Btk(lo) B cells. A transgenic system creating a reduction in dosage of Btk can therefore be used to identify modifier loci that affect B cell responses and quantitatively rank their contribution to Btk-mediated processes.
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Affiliation(s)
- A B Satterthwaite
- Department of Microbiology, Immunology, and Molecular Genetics, and Howard Hughes Medical Institute, University of California, Los Angeles, CA 90095, USA
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26
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Shioi T, Kang PM, Douglas PS, Hampe J, Yballe CM, Lawitts J, Cantley LC, Izumo S. The conserved phosphoinositide 3-kinase pathway determines heart size in mice. EMBO J 2000; 19:2537-48. [PMID: 10835352 PMCID: PMC212739 DOI: 10.1093/emboj/19.11.2537] [Citation(s) in RCA: 446] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/1999] [Revised: 03/13/2000] [Accepted: 03/16/2000] [Indexed: 12/28/2022] Open
Abstract
Phosphoinositide 3-kinase (PI3K) has been shown to regulate cell and organ size in Drosophila, but the role of PI3K in vertebrates in vivo is not well understood. To examine the role of PI3K in intact mammalian tissue, we have created and characterized transgenic mice expressing constitutively active or dominant-negative mutants of PI3K in the heart. Cardiac- specific expression of constitutively active PI3K resulted in mice with larger hearts, while dominant-negative PI3K resulted in mice with smaller hearts. The increase or decrease in heart size was associated with comparable increase or decrease in myocyte size. Cardiomyopathic changes, such as myocyte necrosis, apoptosis, interstitial fibrosis or contractile dysfunction, were not observed in either of the transgenic mice. Thus, the PI3K pathway is necessary and sufficient to promote organ growth in mammals.
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Affiliation(s)
- T Shioi
- Cardiovascular Division, Beth Israel Deaconess Medical Center and Departments of Medicine and Cell Biology, Harvard Medical School, Boston, MA 02215, USA
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27
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Lu-Kuo JM, Fruman DA, Joyal DM, Cantley LC, Katz HR. Impaired kit- but not FcepsilonRI-initiated mast cell activation in the absence of phosphoinositide 3-kinase p85alpha gene products. J Biol Chem 2000; 275:6022-9. [PMID: 10681597 DOI: 10.1074/jbc.275.8.6022] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The class I(A) phosphoinositide 3-kinases (PI3Ks) consist of a 110-kDa catalytic domain and a regulatory subunit encoded by the p85alpha, p85beta, or p55gamma genes. We have determined the effects of disrupting the p85alpha gene on the responses of mast cells stimulated by the cross-linking of Kit and FcepsilonRI, receptors that reflect innate and adaptive responses, respectively. The absence of p85alpha gene products partially inhibited Kit ligand/stem cell factor-induced secretory granule exocytosis, proliferation, and phosphorylation of the serine/threonine kinase Akt. In contrast, p85alpha gene products were not required for FcepsilonRI-initiated exocytosis and phosphorylation of Akt. LY294002, which inhibits all classes of PI3Ks, strongly suppressed Kit- and FcepsilonRI-induced responses in p85alpha -/- mast cells, revealing the contribution of another PI3K family member(s). In contrast to B lymphocytes, mast cell proliferation was not dependent on Bruton's tyrosine kinase, a downstream effector of PI3K, revealing a distinct pathway of PI3K-dependent proliferation in mast cells. Our findings represent the first example of receptor-specific usage of different PI3K family members in a single cell type. In addition, because Kit- but not FcepsilonRI-initiated signaling is associated with mast cell proliferation, the results provide evidence that distinct biologic functions signaled by these two receptors may reflect differential usage of PI3Ks.
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Affiliation(s)
- J M Lu-Kuo
- Department of Medicine, Harvard Medical School, Boston, Massachusetts 02115, USA
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28
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Tolias KF, Hartwig JH, Ishihara H, Shibasaki Y, Cantley LC, Carpenter CL. Type Ialpha phosphatidylinositol-4-phosphate 5-kinase mediates Rac-dependent actin assembly. Curr Biol 2000; 10:153-6. [PMID: 10679324 DOI: 10.1016/s0960-9822(00)00315-8] [Citation(s) in RCA: 203] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Action polymerization is essential for a variety of cellular processes including movement, cell division and shape change. The induction of actin polymerization requires the generation of free actin filament barbed ends, which results from the severing or uncapping of pre-existing actin filaments [1] [2], or de novo nucleation, initiated by the Arp2/3 complex [3] [4] [5] [6] [7]. Although little is known about the signaling pathways that regulate actin assembly, small GTPases of the Rho family appear to be necessary [8] [9] [10] [11]. In thrombin-stimulated platelets, the Rho family GTPase Rac1 induces actin polymerization by stimulating the uncapping of actin filament barbed ends [2]. The mechanism by which Rac regulates uncapping is unclear, however. We previously demonstrated that Rac interacts with a type I phosphatidylinositol-4-phosphate 5-kinase (PIP 5-kinase) in a GTP-independent manner [12] [13]. Because PIP 5-kinases synthesize phosphatidylinositol-4,5-bisphosphate (PI(4,5)P(2)), a lipid that dissociates capping proteins from the barbed ends of actin filaments [14] [15] [16], they are good candidates for mediating the effects of Rac on actin assembly. Here, we have identified the Rac-associated PIP 5-kinase as the PIP 5-kinase isoforms alpha and beta. When added to permeabilized platelets, PIP 5-kinase alpha induced actin filament uncapping and assembly. In contrast, a kinase-inactive PIP 5-kinase alpha mutant failed to induce actin assembly and blocked assembly stimulated by thrombin or Rac. Furthermore, thrombin- or Rac-induced actin polymerization was inhibited by a point mutation in the carboxyl terminus of Rac that disrupts PIP 5-kinase binding. These results demonstrate that PIP 5-kinase alpha is a critical mediator of thrombin- and Rac-dependent actin assembly.
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Affiliation(s)
- K F Tolias
- Division of Signal Transduction, Departments of Cell Biology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston 02115, USA
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29
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Bunnell SC, Diehn M, Yaffe MB, Findell PR, Cantley LC, Berg LJ. Biochemical interactions integrating Itk with the T cell receptor-initiated signaling cascade. J Biol Chem 2000; 275:2219-30. [PMID: 10636929 DOI: 10.1074/jbc.275.3.2219] [Citation(s) in RCA: 216] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Itk, a Tec family tyrosine kinase, acts downstream of Lck and phosphatidylinositol 3'-kinase to facilitate T cell receptor (TCR)-dependent calcium influxes and increases in extracellular-regulated kinase activity. Here we demonstrate interactions between Itk and crucial components of TCR-dependent signaling pathways. First, the inositide-binding pocket of the Itk pleckstrin homology domain directs the constitutive association of Itk with buoyant membranes that are the primary site of TCR activation and are enriched in both Lck and LAT. This association is required for the transphosphorylation of Itk. Second, the Itk proline-rich region binds to Grb2 and LAT. Third, the Itk Src homology (SH3) 3 and SH2 domains interact cooperatively with Syk-phosphorylated SLP-76. Notably, SLP-76 contains a predicted binding motif for the Itk SH2 domain and binds to full-length Itk in vitro. Finally, we show that kinase-inactive Itk can antagonize the SLP-76-dependent activation of NF-AT. The inhibition of NF-AT activation depends on the Itk pleckstrin homology domain, proline-rich region, and SH2 domain. Together, these observations suggest that multivalent interactions recruit Itk to LAT-nucleated signaling complexes and facilitate the activation of LAT-associated phospholipase Cgamma1 by Itk.
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Affiliation(s)
- S C Bunnell
- Department of Pathology, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA
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30
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Abstract
We have recently demonstrated that the D3-phosphoinositide phosphatidylinositol 3,4,5-trisphosphate (PtdIns-3,4,5-P(3)) is critical for producing sustained calcium signals through its role in promoting the function of TEC family tyrosine kinases such as Bruton's tyrosine kinase. Although PtdIns-3,4,5-P(3) can potentially be synthesized by any of several types of phosphoinositide 3-kinases (PI3Ks), B cell receptor (BCR)-induced PtdIns-3,4,5-P(3) production is thought to occur primarily through the activation of the class Ia (p85/p110) PI3Ks. This process has been proposed to be mediated by an interaction between the Src family kinase LYN and the p85 subunit of PI3K and/or through p85 membrane recruitment mediated by CBL and/or CD19. However, calcium signaling and other PI3K-dependent signals are relatively preserved in a LYN kinase-deficient B lymphocyte cell line, suggesting that an alternative pathway for PI3K activation exists. As SYK/ZAP70 kinases are upstream from many BCR-initiated signaling events, we directly analyzed SYK-dependent accumulation of both PtdIns-3,4,5-P(3) and PtdIns-3,4-P(2) in B cell receptor signaling using both dominant negative and genetic knockout approaches. Both methods indicate that SYK is upstream of, and necessary for, a significant portion of BCR-induced PtdIns-3,4, 5-P(3) production. Whereas CD19 does not appear to be involved in this SYK-dependent pathway, the SYK substrate CBL is likely involved as the dominant negative SYK markedly attenuates CBL tyrosine phosphorylation and completely blocks the BCR-dependent association of CBL with p85 PI3K.
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Affiliation(s)
- L O Beitz
- Laboratory of Allergy, Beth Israel Deaconness Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA
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31
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32
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Poy F, Yaffe MB, Sayos J, Saxena K, Morra M, Sumegi J, Cantley LC, Terhorst C, Eck MJ. Crystal structures of the XLP protein SAP reveal a class of SH2 domains with extended, phosphotyrosine-independent sequence recognition. Mol Cell 1999; 4:555-61. [PMID: 10549287 DOI: 10.1016/s1097-2765(00)80206-3] [Citation(s) in RCA: 203] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
SAP, the product of the gene mutated in X-linked lymphoproliferative syndrome (XLP), consists of a single SH2 domain that has been shown to bind the cytoplasmic tail of the lymphocyte coreceptor SLAM. Here we describe structures that show that SAP binds phosphorylated and nonphosphorylated SLAM peptides in a similar mode, with the tyrosine or phosphotyrosine residue inserted into the phosphotyrosine-binding pocket. We find that specific interactions with residues N-terminal to the tyrosine, in addition to more characteristic C-terminal interactions, stabilize the complexes. A phosphopeptide library screen and analysis of mutations identified in XLP patients confirm that these extended interactions are required for SAP function. Further, we show that SAP and the similar protein EAT-2 recognize the sequence motif TIpYXX(V/I).
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Affiliation(s)
- F Poy
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts 02115, USA
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33
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Abstract
The flow of information from calcium-mobilizing receptors to nuclear factor of activated T cells (NFAT)-dependent genes is critically dependent on interaction between the phosphatase calcineurin and the transcription factor NFAT. A high-affinity calcineurin-binding peptide was selected from combinatorial peptide libraries based on the calcineurin docking motif of NFAT. This peptide potently inhibited NFAT activation and NFAT-dependent expression of endogenous cytokine genes in T cells, without affecting the expression of other cytokines that require calcineurin but not NFAT. Substitution of the optimized peptide sequence into the natural calcineurin docking site increased the calcineurin responsiveness of NFAT. Compounds that interfere selectively with the calcineurin-NFAT interaction without affecting calcineurin phosphatase activity may be useful as therapeutic agents that are less toxic than current drugs.
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Affiliation(s)
- J Aramburu
- Department of Pathology, Harvard Medical School, Boston, MA 02115, USA
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34
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Aksoy IA, Ramsey MJ, Fruman DA, Aksoy S, Cantley LC, Tucker JD, Roberts TM. Mouse phosphoinositide 3-kinase p110alpha gene: cloning, structural organization, and localization to chromosome 3 band B. Biochem Biophys Res Commun 1999; 262:438-42. [PMID: 10462494 DOI: 10.1006/bbrc.1999.1150] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Phosphoinositide 3-Kinases (PI3-Kinases) are a family of dual specificity enzymes with a unique lipid kinase activity toward the D-3 position of the inositol ring of phosphoinositides and a less well characterized serine/threonine protein kinase activity. Class IA PI3-Kinases comprise a 110-120 kDa catalytic subunit (usually termed p110) and an 85 kDa or 50 to 55 kDa regulatory subunit (often called p85). cDNAs for three mammalian Class IA PI3-Kinase catalytic subunits designated p110alpha, p110beta, and p110delta have been cloned from several species. A YAC clone for the human p110alpha gene has also been cloned and mapped to chromosome 3q26.3. However, structural organization for any of the PI3-Kinase p110alpha genes has not been reported. Here, we report the cloning, structural organization, and chromosomal localization of the mouse PI3-Kinase p110alpha gene. The translated portion of the mouse p110alpha gene is encoded by 19 exons that span at least 24 kb. Dual color fluorescence in situ hybridization (FISH) was performed to determine the chromosomal localization of the mouse PI3-Kinase p110alpha gene. FISH results and DAPI banding demonstrated localization of the p110alpha gene to band B on mouse chromosome 3, a region syntenic with human chromosome 3q26.3.
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Affiliation(s)
- I A Aksoy
- Dana Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts, 02115, USA
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35
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Rittinger K, Budman J, Xu J, Volinia S, Cantley LC, Smerdon SJ, Gamblin SJ, Yaffe MB. Structural analysis of 14-3-3 phosphopeptide complexes identifies a dual role for the nuclear export signal of 14-3-3 in ligand binding. Mol Cell 1999; 4:153-66. [PMID: 10488331 DOI: 10.1016/s1097-2765(00)80363-9] [Citation(s) in RCA: 411] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
We have solved the high-resolution X-ray structure of 14-3-3 bound to two different phosphoserine peptides, representing alternative substrate-binding motifs. These structures reveal an evolutionarily conserved network of peptide-protein interactions within all 14-3-3 isotypes, explain both binding motifs, and identify a novel intrachain phosphorylation-mediated loop structure in one of the peptides. A 14-3-3 mutation disrupting Raf signaling alters the ligand-binding cleft, selecting a different phosphopeptide-binding motif and different substrates than the wild-type protein. Many 14-3-3: peptide contacts involve a C-terminal amphipathic alpha helix containing a putative nuclear export signal, implicating this segment in both ligand and Crm1 binding. Structural homology between the 14-3-3 NES structure and those within I kappa B alpha and p53 reveals a conserved topology recognized by the Crm1 nuclear export machinery.
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Affiliation(s)
- K Rittinger
- Divison of Protein Structure, National Institute for Medical Research, London, United Kingdom
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36
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Fruman DA, Snapper SB, Yballe CM, Alt FW, Cantley LC. Phosphoinositide 3-kinase knockout mice: role of p85alpha in B cell development and proliferation. Biochem Soc Trans 1999; 27:624-9. [PMID: 10917654 DOI: 10.1042/bst0270624] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- D A Fruman
- Beth Israel Deaconess Medical Center and Department of Cell Biology, Harvard Medical School, Boston, MA 02215, USA
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37
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Affiliation(s)
- R E Meyers
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA
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38
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Rathbun GA, Ziv Y, Lai JH, Hill D, Abraham RH, Shiloh Y, Cantley LC. ATM and lymphoid malignancies; use of oriented peptide libraries to identify novel substrates of ATM critical in downstream signaling pathways. Curr Top Microbiol Immunol 1999; 246:267-73; discussion 274. [PMID: 10396065 DOI: 10.1007/978-3-642-60162-0_33] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Affiliation(s)
- G A Rathbun
- Center for Blood Research, Harvard Medical School, USA
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39
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Affiliation(s)
- D A Fruman
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA
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40
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Cantley LC, Neel BG. New insights into tumor suppression: PTEN suppresses tumor formation by restraining the phosphoinositide 3-kinase/AKT pathway. Proc Natl Acad Sci U S A 1999; 96:4240-5. [PMID: 10200246 PMCID: PMC33561 DOI: 10.1073/pnas.96.8.4240] [Citation(s) in RCA: 1472] [Impact Index Per Article: 58.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The most recently discovered PTEN tumor suppressor gene has been found to be defective in a large number of human cancers. In addition, germ-line mutations in PTEN result in the dominantly inherited disease Cowden syndrome, which is characterized by multiple hamartomas and a high proclivity for developing cancer. A series of publications over the past year now suggest a mechanism by which PTEN loss of function results in tumors. PTEN appears to negatively control the phosphoinositide 3-kinase signaling pathway for regulation of cell growth and survival by dephosphorylating the 3 position of phosphoinositides.
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Affiliation(s)
- L C Cantley
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA.
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41
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Abstract
In eukaryotic cells, phosphatidylinositol can be phosphorylated on the inositol ring by a series of kinases to produce at least seven distinct phosphoinositides. These lipids have been implicated in a variety of cellular processes, including calcium regulation, actin rearrangement, vesicle trafficking, cell survival and mitogenesis. The phosphorylated lipids can act as precursors of second messengers or act directly to recruit specific signaling proteins to the membrane. A number of the kinases responsible for producing these lipids have been purified and their cDNA clones have been isolated. The most well characterized of these enzymes are the phosphoinositide 3-kinases. However, progress has also been made in the characterization of phosphatidylinositol 4-kinases and phosphatidylinositol-4-phosphate 5-kinases. In addition, new pathways involving phosphatidylinositol-5-phosphate 4-kinases, phosphatidylinositol-3-phosphate 5-kinases and phosphatidylinositol-3-phosphate 4-kinases have recently been described. The various enzymes and pathways involved in the synthesis of cellular phosphoinositides will be discussed.
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Affiliation(s)
- K F Tolias
- Beth Israel Deaconess Medical Center, Harvard Institutes of Medicine, Boston, MA 02215, USA
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42
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Affiliation(s)
- L E Rameh
- Department of Cell Biology, Harvard Medical School and Division of Signal Transduction, Beth Israel Deaconess Medical Center, Boston, Massachusetts 02115, USA
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43
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Gupta N, Scharenberg AM, Fruman DA, Cantley LC, Kinet JP, Long EO. The SH2 domain-containing inositol 5'-phosphatase (SHIP) recruits the p85 subunit of phosphoinositide 3-kinase during FcgammaRIIb1-mediated inhibition of B cell receptor signaling. J Biol Chem 1999; 274:7489-94. [PMID: 10066815 DOI: 10.1074/jbc.274.11.7489] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Coligation of FcgammaRIIb1 with the B cell receptor (BCR) or FcepsilonRI on mast cells inhibits B cell or mast cell activation. Activity of the inositol phosphatase SHIP is required for this negative signal. In vitro, SHIP catalyzes the conversion of the phosphoinositide 3-kinase (PI3K) product phosphatidylinositol 3,4, 5-trisphosphate (PIP3) into phosphatidylinositol 3,4-bisphosphate. Recent data demonstrate that coligation of FcgammaRIIb1 with BCR inhibits PIP3-dependent Btk (Bruton's tyrosine kinase) activation and the Btk-dependent generation of inositol trisphosphate that regulates sustained calcium influx. In this study, we provide evidence that coligation of FcgammaRIIb1 with BCR induces binding of PI3K to SHIP. This interaction is mediated by the binding of the SH2 domains of the p85 subunit of PI3K to a tyrosine-based motif in the C-terminal region of SHIP. Furthermore, the generation of phosphatidylinositol 3,4-bisphosphate was only partially reduced during coligation of BCR with FcgammaRIIb1 despite a drastic reduction in PIP3. In contrast to the complete inhibition of Tec kinase-dependent calcium signaling, activation of the serine/threonine kinase Akt was partially preserved during BCR and FcgammaRIIb1 coligation. The association of PI3K with SHIP may serve to activate PI3K and to regulate downstream events such as B cell activation-induced apoptosis.
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MESH Headings
- 3T3 Cells
- Animals
- Antigens, CD/metabolism
- Mice
- Oncogene Protein v-akt
- Phosphatidylinositol 3-Kinases/chemistry
- Phosphatidylinositol 3-Kinases/metabolism
- Phosphatidylinositol 4,5-Diphosphate/metabolism
- Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases
- Phosphoric Monoester Hydrolases/metabolism
- Phosphorylation
- Protein Binding
- Receptors, Antigen, B-Cell/antagonists & inhibitors
- Receptors, Antigen, B-Cell/metabolism
- Receptors, IgG/metabolism
- Retroviridae Proteins, Oncogenic/metabolism
- Signal Transduction
- Tyrosine/metabolism
- src Homology Domains
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Affiliation(s)
- N Gupta
- Laboratory of Immunogenetics, NIAID, National Institutes of Health, Rockville, Maryland 20852-1727, USA
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44
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Fruman DA, Snapper SB, Yballe CM, Davidson L, Yu JY, Alt FW, Cantley LC. Impaired B cell development and proliferation in absence of phosphoinositide 3-kinase p85alpha. Science 1999; 283:393-7. [PMID: 9888855 DOI: 10.1126/science.283.5400.393] [Citation(s) in RCA: 498] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Phosphoinositide 3-kinase (PI3K) activation has been implicated in many cellular responses, including fibroblast growth, transformation, survival, and chemotaxis. Although PI3K is activated by several agents that stimulate T and B cells, the role of PI3K in lymphocyte function is not clear. The mouse gene encoding the PI3K adapter subunit p85alpha and its splice variants p55alpha and p50alpha was disrupted. Most p85alpha-p55alpha-p50alpha-/- mice die within days after birth. Lymphocyte development and function was studied with the use of the RAG2-deficient blastocyst complementation system. Chimeric mice had reduced numbers of peripheral mature B cells and decreased serum immunoglobulin. The B cells that developed had diminished proliferative responses to antibody to immunoglobulin M, antibody to CD40, and lipopolysaccharide stimulation and decreased survival after incubation with interleukin-4. In contrast, T cell development and proliferation was normal. This phenotype is similar to defects observed in mice lacking the tyrosine kinase Btk.
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Affiliation(s)
- D A Fruman
- Division of Signal Transduction, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA.
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45
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Crovello CS, Lai C, Cantley LC, Carraway KL. Differential signaling by the epidermal growth factor-like growth factors neuregulin-1 and neuregulin-2. J Biol Chem 1998; 273:26954-61. [PMID: 9756944 DOI: 10.1074/jbc.273.41.26954] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The neuregulins comprise a subfamily of epidermal growth factor (EGF)-like growth factors that elicit diverse cellular responses by activating members of the ErbB family of receptor tyrosine kinases. Although neuregulin-1 and neuregulin-2 are both binding ligands for the ErbB3 and ErbB4 receptors, they exhibit distinct biological activities depending on cellular context. In MDA-MB-468 human mammary tumor cells, neuregulin-2beta (NRG2beta) inhibits cell growth, whereas neuregulin-1beta (NRG1beta) does not. In these cells, NRG2beta appears to preferentially act through the EGF receptor, stimulating receptor tyrosine phosphorylation and the recruitment of phospholipase C-gamma, Cbl, SHP2, and Shc to that receptor. NRG1beta preferentially acts through ErbB3 in these cells by stimulating the tyrosine phosphorylation and recruitment of phosphatidylinositol 3-kinase and Shc to that receptor. In MDA-MB-453 cells, both NRG1beta and NRG2beta stimulate the tyrosine phosphorylation of the ErbB2 and ErbB3 receptors to similar extents, but only NRG1beta potently stimulates morphological changes consistent with their differentiation. The profiles of SH2 domain-containing proteins that are efficiently recruited to activated receptors differ for the two factors. These observations indicate that despite their overlapping receptor specificity, the neuregulins exhibit distinct biological and biochemical properties. Since both of these cell lines express only two of the known ErbB receptors, our results imply that EGF-like ligands might elicit differential signaling within the context of a single receptor heterodimer.
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Affiliation(s)
- C S Crovello
- Division of Signal Transduction, Beth Israel Deaconess Medical Center and the Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02215, USA
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46
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Abstract
Phosphatidylinositol, a component of eukaryotic cell membranes, is unique among phospholipids in that its head group can be phosphorylated at multiple free hydroxyls. Several phosphorylated derivatives of phosphatidylinositol, collectively termed phosphoinositides, have been identified in eukaryotic cells from yeast to mammals. Phosphoinositides are involved in the regulation of diverse cellular processes, including proliferation, survival, cytoskeletal organization, vesicle trafficking, glucose transport, and platelet function. The enzymes that phosphorylate phosphatidylinositol and its derivatives are termed phosphoinositide kinases. Recent advances have challenged previous hypotheses about the substrate selectivity of different phosphoinositide kinase families. Here we re-examine the pathways of phosphoinositide synthesis and the enzymes involved.
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Affiliation(s)
- D A Fruman
- Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts 02215, USA.
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47
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48
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Rameh LE, Rhee SG, Spokes K, Kazlauskas A, Cantley LC, Cantley LG. Phosphoinositide 3-kinase regulates phospholipase Cgamma-mediated calcium signaling. J Biol Chem 1998; 273:23750-7. [PMID: 9726983 DOI: 10.1074/jbc.273.37.23750] [Citation(s) in RCA: 188] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
It has been demonstrated that the lipid products of the phosphoinositide 3-kinase (PI3K) can associate with the Src homology 2 (SH2) domains of specific signaling molecules and modify their actions. In the current experiments, phosphatidylinositol 3,4, 5-trisphosphate (PtdIns-3,4,5-P3) was found to bind to the C-terminal SH2 domain of phospholipase Cgamma (PLCgamma) with an apparent Kd of 2.4 microM and to displace the C-terminal SH2 domain from the activated platelet-derived growth factor receptor (PDGFR). To investigate the in vivo relevance of this observation, intracellular inositol trisphosphate (IP3) generation and calcium release were examined in HepG2 cells expressing a series of PDGFR mutants that activate PLCgamma with or without receptor association with PI3K. Coactivation of PLCgamma and PI3K resulted in an approximately 40% increase in both intracellular IP3 generation and intracellular calcium release as compared with selective activation of PLCgamma. Similarly, the addition of wortmannin or LY294002 to cells expressing the wild-type PDGFR inhibited the release of intracellular calcium. Thus, generation of PtdIns-3,4,5-P3 by receptor-associated PI3K causes an increase in IP3 production and intracellular calcium release, potentially via enhanced PtdIns-4, 5-P2 substrate availability due to PtdIns-3,4,5-P3-mediated recruitment of PLCgamma to the lipid bilayer.
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Affiliation(s)
- L E Rameh
- Division of Signal Transduction, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA
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49
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Nishikawa K, Toker A, Wong K, Marignani PA, Johannes FJ, Cantley LC. Association of protein kinase Cmu with type II phosphatidylinositol 4-kinase and type I phosphatidylinositol-4-phosphate 5-kinase. J Biol Chem 1998; 273:23126-33. [PMID: 9722541 DOI: 10.1074/jbc.273.36.23126] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Protein kinase Cmu (PKCmu), also named protein kinase D, is an unusual member of the PKC family that has a putative transmembrane domain and pleckstrin homology domain. This enzyme has a substrate specificity distinct from other PKC isoforms (Nishikawa, K., Toker, A., Johannes, F. J., Songyang, Z., and Cantley, L. C. (1997) J. Biol. Chem. 272, 952-960), and its mechanism of regulation is not yet clear. Here we show that PKCmu forms a complex in vivo with a phosphatidylinositol 4-kinase and a phosphatidylinositol-4-phosphate 5-kinase. A region of PKCmu between the amino-terminal transmembrane domain and the pleckstrin homology domain is shown to be involved in the association with the lipid kinases. Interestingly, a kinase-dead point mutant of PKCmu failed to associate with either lipid kinase activity, indicating that autophosphorylation may be required to expose the lipid kinase interaction domain. Furthermore, the subcellular distribution of the PKCmu-associated lipid kinases to the particulate fraction depends on the presence of the amino-terminal region of PKCmu including the predicted transmembrane region. These results suggest a novel model in which the non-catalytic region of PKCmu acts as a scaffold for assembly of enzymes involved in phosphoinositide synthesis at specific membrane locations.
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Affiliation(s)
- K Nishikawa
- Division of Signal Transduction, Beth Israel Deaconess Medical Center and Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA.
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50
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Parker D, Jhala US, Radhakrishnan I, Yaffe MB, Reyes C, Shulman AI, Cantley LC, Wright PE, Montminy M. Analysis of an activator:coactivator complex reveals an essential role for secondary structure in transcriptional activation. Mol Cell 1998; 2:353-9. [PMID: 9774973 DOI: 10.1016/s1097-2765(00)80279-8] [Citation(s) in RCA: 131] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
Ser-133 phosphorylation of CREB within the kinase-inducible domain (KID) promotes target gene activation via complex formation with the KIX domain of the coactivator CBP. Concurrent phosphorylation of CREB at Ser-142 inhibits transcriptional induction via an unknown mechanism. Unstructured in the free state, KID folds into a helical structure upon binding to KIX. Using site-directed mutagenesis based on the NMR structure of the KID:KIX complex, we have examined the mechanisms by which Ser-133 and Ser-142 phosphorylation regulate CREB activity. Our results indicate that phospho-Ser-133 stablizes whereas phospho-Ser-142 disrupts secondary structure-mediated interactions between CREB and CBP. Thus, differential phosphorylation of CREB may form the basis by which upstream signals regulate the specificity of target gene activation.
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Affiliation(s)
- D Parker
- Joslin Diabetes Center, Research Division, Boston, Massachusetts, USA
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