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Downward J, Parker PJ, Vanhaesebroeck B. Michael D. Waterfield. Biochem J 2023; 480:1475-1478. [PMID: 37732645 PMCID: PMC10586771 DOI: 10.1042/bcj20230368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/22/2023]
Affiliation(s)
- Julian Downward
- Oncogene Biology Laboratory, The Francis Crick Institute, 1 Midland Road London NW1 1AT, U.K
| | - Peter J. Parker
- Protein Phosphorylation Laboratory, Francis Crick Institute, 1 Midland Road, London NW1 1AT, U.K
- School of Cancer and Pharmaceutical Sciences, New Hunt's House, Guy's Campus, London SE1 1UL, U.K
| | - Bart Vanhaesebroeck
- UCL Cancer Institute, University College London, 72 Huntley Street, London WC1E 6BT, U.K
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Overcoming Resistance to Therapies Targeting the MAPK Pathway in BRAF-Mutated Tumours. JOURNAL OF ONCOLOGY 2020; 2020:1079827. [PMID: 32411231 PMCID: PMC7199609 DOI: 10.1155/2020/1079827] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 11/21/2019] [Accepted: 11/29/2019] [Indexed: 12/12/2022]
Abstract
Overactivation of the mitogen-activated protein kinase (MAPK) pathway is an important driver of many human cancers. First line, FDA-approved therapies targeting MAPK signalling, which include BRAF and MEK inhibitors, have variable success across cancers, and a significant number of patients quickly develop resistance. In recent years, a number of preclinical studies have reported alternative methods of overcoming resistance, which include promoting apoptosis, modulating autophagy, and targeting mitochondrial metabolism. This review summarizes mechanisms of resistance to approved MAPK-targeted therapies in BRAF-mutated cancers and discusses novel preclinical approaches to overcoming resistance.
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Hassett MR, Sternberg AR, Roepe PD. Inhibition of Human Class I vs Class III Phosphatidylinositol 3′-Kinases. Biochemistry 2017; 56:4326-4334. [DOI: 10.1021/acs.biochem.7b00413] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Matthew R. Hassett
- Department of Chemistry and Department of Biochemistry & Cellular & Molecular Biology, Georgetown University, 37th and O Streets NW, Washington, D.C. 20057, United States
| | - Anna R. Sternberg
- Department of Chemistry and Department of Biochemistry & Cellular & Molecular Biology, Georgetown University, 37th and O Streets NW, Washington, D.C. 20057, United States
| | - Paul D. Roepe
- Department of Chemistry and Department of Biochemistry & Cellular & Molecular Biology, Georgetown University, 37th and O Streets NW, Washington, D.C. 20057, United States
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4
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Chae HJ, Ha MS, Yun DH, Pae HO, Chung HT, Chae SW, Jung YK, Kim HR. Mechanism of Cyclosporine-induced Overgrowth in Gingiva. J Dent Res 2016; 85:515-9. [PMID: 16723647 DOI: 10.1177/154405910608500607] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Cyclosporine A (CsA) is a widely used immunosuppressant but with significant side-effects, such as gingival overgrowth. This study investigates how CsA induces gingival proliferation and shows the effects of the CsA-associated signaling messengers, IL-6 and TGF-β1, on gingival proliferation. CsA increased both IL-6 and TGF-β1 levels. In addition to CsA, an IL-6 or TGF-β1 treatment also induced gingival fibroblast proliferation. Inhibiting the cytokine resulted in the suppression of CsA-induced proliferation. MAPKs and PI3K are known to be involved in cell proliferation. Therefore, the effect of CsA on the kinase activities was examined. The results showed that both p38 MAPK and PI3K are essential for gingival fibroblast proliferation. TGF-β1 and IL-6 and their associated signaling transduction may be novel bona fide molecular targets for the prevention of gingival overgrowth in CsA-treated patients. (Abbreviations: MAPK, mitogen-activated protein kinase; PI3K, phosphatidylinositol 3-kinase.)
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Affiliation(s)
- H-J Chae
- Department of Dental Pharmacology and Wonkwang Biomaterial Implant Research Institute, School of Dentistry, Wonkwang University, Iksan, Chonbuk, South Korea
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5
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Altintas O, Park S, Lee SJV. The role of insulin/IGF-1 signaling in the longevity of model invertebrates, C. elegans and D. melanogaster. BMB Rep 2016; 49:81-92. [PMID: 26698870 PMCID: PMC4915121 DOI: 10.5483/bmbrep.2016.49.2.261] [Citation(s) in RCA: 130] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Indexed: 01/08/2023] Open
Abstract
Insulin/insulin-like growth factor (IGF)-1 signaling (IIS) pathway regulates
aging in many organisms, ranging from simple invertebrates to mammals, including
humans. Many seminal discoveries regarding the roles of IIS in aging and
longevity have been made by using the roundworm Caenorhabditis
elegans and the fruit fly Drosophila melanogaster. In this
review, we describe the mechanisms by which various IIS components regulate
aging in C. elegans and D. melanogaster. We
also cover systemic and tissue-specific effects of the IIS components on the
regulation of lifespan. We further discuss IIS-mediated physiological processes
other than aging and their effects on human disease models focusing on
C. elegans studies. As both C. elegans and
D. melanogaster have been essential for key findings
regarding the effects of IIS on organismal aging in general, these invertebrate
models will continue to serve as workhorses to help our understanding of
mammalian aging. [BMB Reports 2016; 49(2): 81-92]
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Affiliation(s)
- Ozlem Altintas
- School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, Pohang 37673, Korea
| | - Sangsoon Park
- Department of Life Sciences, Pohang University of Science and Technology, Pohang 37673, Korea
| | - Seung-Jae V Lee
- School of Interdisciplinary Bioscience and Bioengineering, Department of Life Sciences, and Information Technology Convergence Engineering, Pohang University of Science and Technology, Pohang 37673, Korea
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6
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Endothelial PI3K-C2α, a class II PI3K, has an essential role in angiogenesis and vascular barrier function. Nat Med 2012; 18:1560-9. [PMID: 22983395 DOI: 10.1038/nm.2928] [Citation(s) in RCA: 168] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2012] [Accepted: 08/10/2012] [Indexed: 12/11/2022]
Abstract
The class II α-isoform of phosphatidylinositol 3-kinase (PI3K-C2α) is localized in endosomes, the trans-Golgi network and clathrin-coated vesicles; however, its functional role is not well understood. Global or endothelial-cell-specific deficiency of PI3K-C2α resulted in embryonic lethality caused by defects in sprouting angiogenesis and vascular maturation. PI3K-C2α knockdown in endothelial cells resulted in a decrease in the number of PI3-phosphate-enriched endosomes, impaired endosomal trafficking, defective delivery of VE-cadherin to endothelial cell junctions and defective junction assembly. PI3K-C2α knockdown also impaired endothelial cell signaling, including vascular endothelial growth factor receptor internalization and endosomal RhoA activation. Together, the effects of PI3K-C2α knockdown led to defective endothelial cell migration, proliferation, tube formation and barrier integrity. Endothelial PI3K-C2α deficiency in vivo suppressed postischemic and tumor angiogenesis and diminished vascular barrier function with a greatly augmented susceptibility to anaphylaxis and a higher incidence of dissecting aortic aneurysm formation in response to angiotensin II infusion. Thus, PI3K-C2α has a crucial role in vascular formation and barrier integrity and represents a new therapeutic target for vascular disease.
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7
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Powis KV, MacDougall LK. The localisation of PtdIns3P in Drosophila fat responds to nutrients but not insulin: a role for Class III but not Class II phosphoinositide 3-kinases. Cell Signal 2011; 23:1153-61. [PMID: 21385607 DOI: 10.1016/j.cellsig.2011.02.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2010] [Revised: 02/16/2011] [Accepted: 02/28/2011] [Indexed: 12/29/2022]
Abstract
PtdIns3P and PtdIns(3,4,5)P(3) are regulated differently in fat body in response to nutritional status and insulin signalling. In feeding larvae PtdIns(3,4,5)P(3) is upregulated at the cell membrane where it is generated in response to insulin signalling. In contrast PtdIns3P is down regulated in the fat body of well-fed larvae but on starvation it accumulates in punctate vesicles throughout the cytoplasm and on refeeding it relocalises to vesicles at the periphery of the cell. Both responses are independent of insulin signalling and on the presence of glutamine which has previously been linked to nutritional sensing. We find that both Class II and Class III PI3Ks are capable of generating PtdIns3P in vivo but the source of PtdIns3P in the fat body and the response to nutritional status can be exclusively accounted for by Class III PI3K activity.
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Affiliation(s)
- Katie V Powis
- Faculty of Life Sciences, Michael Smith Building, The University of Manchester, Oxford Road, Manchester, United Kingdom
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9
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Lee Y, Kim ES, Choi Y, Hwang I, Staiger CJ, Chung YY, Lee Y. The Arabidopsis phosphatidylinositol 3-kinase is important for pollen development. PLANT PHYSIOLOGY 2008; 147:1886-97. [PMID: 18515640 PMCID: PMC2492648 DOI: 10.1104/pp.108.121590] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2008] [Accepted: 05/02/2008] [Indexed: 05/18/2023]
Abstract
Phosphatidylinositol 3-kinase has been reported to be important for normal plant growth. To characterize the role of the enzyme further, we attempted to isolate Arabidopsis (Arabidopsis thaliana) plants that do not express the gene, but we could not recover homozygous mutant plants. The progeny of VPS34/vps34 heterozygous plants, harboring a T-DNA insertion, showed a segregation ratio of 1:1:0 for wild-type, heterozygous, and homozygous mutant plants, indicating a gametophytic defect. Genetic transmission analysis showed that the abnormal segregation ratio was due to failure to transmit the mutant allele through the male gametophyte. Microscopic observation revealed that 2-fold higher proportions of pollen grains in heterozygous plants than wild-type plants were dead or showed reduced numbers of nuclei. Many mature pollen grains from the heterozygous plants contained large vacuoles even until the mature pollen stage, whereas pollen from wild-type plants contained many small vacuoles beginning from the vacuolated pollen stage, which indicated that vacuoles in many of the heterozygous mutant pollen did not undergo normal fission after the first mitotic division. Taken together, our results suggest that phosphatidylinositol 3-kinase is essential for vacuole reorganization and nuclear division during pollen development.
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Affiliation(s)
- Yuree Lee
- POSTECH-UZH Global Research Laboratory, Division of Molecular Life Sciences, POSTECH, Pohang 790-784, Korea
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10
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Juhász G, Hill JH, Yan Y, Sass M, Baehrecke EH, Backer JM, Neufeld TP. The class III PI(3)K Vps34 promotes autophagy and endocytosis but not TOR signaling in Drosophila. ACTA ACUST UNITED AC 2008; 181:655-66. [PMID: 18474623 PMCID: PMC2386105 DOI: 10.1083/jcb.200712051] [Citation(s) in RCA: 258] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Degradation of cytoplasmic components by autophagy requires the class III phosphatidylinositol 3 (PI(3))–kinase Vps34, but the mechanisms by which this kinase and its lipid product PI(3) phosphate (PI(3)P) promote autophagy are unclear. In mammalian cells, Vps34, with the proautophagic tumor suppressors Beclin1/Atg6, Bif-1, and UVRAG, forms a multiprotein complex that initiates autophagosome formation. Distinct Vps34 complexes also regulate endocytic processes that are critical for late-stage autophagosome-lysosome fusion. In contrast, Vps34 may also transduce activating nutrient signals to mammalian target of rapamycin (TOR), a negative regulator of autophagy. To determine potential in vivo functions of Vps34, we generated mutations in the single Drosophila melanogaster Vps34 orthologue, causing cell-autonomous disruption of autophagosome/autolysosome formation in larval fat body cells. Endocytosis is also disrupted in Vps34−/− animals, but we demonstrate that this does not account for their autophagy defect. Unexpectedly, TOR signaling is unaffected in Vps34 mutants, indicating that Vps34 does not act upstream of TOR in this system. Instead, we show that TOR/Atg1 signaling regulates the starvation-induced recruitment of PI(3)P to nascent autophagosomes. Our results suggest that Vps34 is regulated by TOR-dependent nutrient signals directly at sites of autophagosome formation.
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Affiliation(s)
- Gábor Juhász
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN 55455, USA
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11
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Abstract
The Class III PI3K (phosphoinositide 3-kinase), Vps34 (vacuolar protein sorting 34), was first described as a component of the vacuolar sorting system in Saccharomyces cerevisiae and is the sole PI3K in yeast. The homologue in mammalian cells, hVps34, has been studied extensively in the context of endocytic sorting. However, hVps34 also plays an important role in the ability of cells to respond to changes in nutrient conditions. Recent studies have shown that mammalian hVps34 is required for the activation of the mTOR (mammalian target of rapamycin)/S6K1 (S6 kinase 1) pathway, which regulates protein synthesis in response to nutrient availability. In both yeast and mammalian cells, Class III PI3Ks are also required for the induction of autophagy during nutrient deprivation. Finally, mammalian hVps34 is itself regulated by nutrients. Thus Class III PI3Ks are implicated in the regulation of both autophagy and, through the mTOR pathway, protein synthesis, and thus contribute to the integration of cellular responses to changing nutritional status.
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12
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Abstract
The class III PI3K (phosphoinositide 3-kinase), Vps34 (vacuolar protein sorting 34), was first identified as a regulator of vacuolar hydrolase sorting in yeast. Unlike other PI3Ks, the Vps34 lipid kinase specifically utilizes phosphatidylinositol as a substrate, producing the single lipid product PtdIns3P. While Vps34 has been studied for some time in the context of endocytosis and vesicular trafficking, it has more recently been implicated as an important regulator of autophagy, trimeric G-protein signalling, and the mTOR (mammalian target of rapamycin) nutrient-sensing pathway. The present paper will focus on studies that describe the regulation of hVps34 (human Vps34) intracellular targeting and enzymatic activity in yeast and mammalian cells.
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Affiliation(s)
- Y Yan
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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13
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Chae HJ, Kim HR, Bae J, Chae SU, Ha KC, Chae SW. Signal transduction of the protective effect of insulin like growth factor-1 on adriamycin-induced apoptosis in cardiac muscle cells. Arch Pharm Res 2004; 27:324-33. [PMID: 15089039 DOI: 10.1007/bf02980068] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
To determine whether Insulin-like growth factor (IGF-I) treatment represents a potential means of enhancing the survival of cardiac muscle cells from adriamycin (ADR)-induced cell death, the present study examined the ability of IGF-I to prevent cell death. The study was performed utilising the embryonic, rat, cardiac muscle cell line, H9C2. Incubating cardiac muscle cells in the presence of adriamycin increased cell death, as determined by MTT assay and annexin V-positive cell number. The addition of 100 ng/mL IGF-I, in the presence of adriamycin, decreased apoptosis. The effect of IGF-I on phosphorylation of PI, a substrate of phosphatidylinositol 3-kinase (PI 3-kinase) or protein kinase B (AKT), was also examined in H9C2 cardiac muscle cells. IGF-I increased the phosphorylation of ERK 1 and 2 and PKC zeta kinase. The use of inhibitors of PI 3-kinase (LY 294002), in the cell death assay, demonstrated partial abrogation of the protective effect of IGF-I. The MEK1 inhibitor-PD098059 and the PKC inhibitor-chelerythrine exhibited no effect on IGF-1-induced cell protection. In the regulatory subunit of PI3K-p85- dominant, negative plasmid-transfected cells, the IGF-1-induced protective effect was reversed. This data demonstrates that IGF-I protects cardiac muscle cells from ADR-induced cell death. Although IGF-I activates several signaling pathways that contribute to its protective effect in other cell types, only activation of PI 3-kinase contributes to this effect in H9C2 cardiac muscle cells.
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Affiliation(s)
- Han-Jung Chae
- Department of Pharmacology, Institute of Cardiovascular Research, School of Medicine, Chonbuk National University, Jeonju 560-180, Korea
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14
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MacDougall LK, Gagou ME, Leevers SJ, Hafen E, Waterfield MD. Targeted expression of the class II phosphoinositide 3-kinase in Drosophila melanogaster reveals lipid kinase-dependent effects on patterning and interactions with receptor signaling pathways. Mol Cell Biol 2004; 24:796-808. [PMID: 14701751 PMCID: PMC343800 DOI: 10.1128/mcb.24.2.796-808.2004] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Phosphoinositide 3-kinases (PI3Ks) can be divided into three distinct classes (I, II, and III) on the basis of their domain structures and the lipid signals that they generate. Functions have been assigned to the class I and class III enzymes but have not been established for the class II PI3Ks. We have obtained the first evidence for a biological function for a class II PI3K by expressing this enzyme during Drosophila melanogaster development and by using deficiencies that remove the endogenous gene. Wild-type and catalytically inactive PI3K_68D transgenes have opposite effects on the number of sensory bristles and on wing venation phenotypes induced by modified epidermal growth factor (EGF) receptor signaling. These results indicate that the endogenous PI3K_68D may act antagonistically to the EGF receptor-stimulated Ras-mitogen-activated protein kinase pathway and downstream of, or parallel to, the Notch receptor. A class II polyproline motif in PI3K_68D can bind the Drk adaptor protein in vitro, primarily via the N-terminal SH3 domain of Drk. Drk may thus be important for the localization of PI3K_68D, allowing it to modify signaling pathways downstream of cell surface receptors. The phenotypes obtained are markedly distinct from those generated by expression of the Drosophila class I PI3K, which affects growth but not pattern formation.
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Affiliation(s)
- Lindsay K MacDougall
- Biomolecular Sciences, University of Manchester Institute of Science and Technology, PO Box 88, Manchester M60 1QD, UK.
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15
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Roggo L, Bernard V, Kovacs AL, Rose AM, Savoy F, Zetka M, Wymann MP, Müller F. Membrane transport in Caenorhabditis elegans: an essential role for VPS34 at the nuclear membrane. EMBO J 2002; 21:1673-83. [PMID: 11927551 PMCID: PMC125367 DOI: 10.1093/emboj/21.7.1673] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Here we present a detailed genetic analysis of let-512/vps34 that encodes the Caenorhabditis elegans homologue of the yeast phosphatidylinositol 3-kinase Vps34p. LET-512/VPS34 has essential functions and is ubiquitously expressed in all tissues and developmental stages. It accumulates at a perinuclear region, and mutations in let-512/vps34 result in an expansion of the outer nuclear membrane as well as in a mislocalization and subsequent complete lack of expression of LRP-1, a C.elegans LDL receptor normally associated with the apical surface of hypodermal cells. Using a GFP::2xFYVE fusion protein we found that the phosphatidylinositol 3-phosphate (PtdIns 3-P) product of LET-512/VPS34 is associated with a multitude of intracellular membranes and vesicles located at the periphery, including endocytic vesicles. We propose that LET-512/VPS34 is required for membrane transport from the outer nuclear membrane towards the cell periphery. Thus, LET-512/VPS34 may regulate the secretory pathway in a much broader range of compartments than was previously suggested for the yeast orthologue.
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Affiliation(s)
- Lorenz Roggo
- Department of Biology, University of Fribourg, CH-1700 Fribourg, Switzerland
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16
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Elge S, Brearley C, Xia HJ, Kehr J, Xue HW, Mueller-Roeber B. An Arabidopsis inositol phospholipid kinase strongly expressed in procambial cells: synthesis of PtdIns(4,5)P2 and PtdIns(3,4,5)P3 in insect cells by 5-phosphorylation of precursors. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2001; 26:561-571. [PMID: 11489170 DOI: 10.1046/j.1365-313x.2001.01051.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
We have cloned a phosphatidylinositol-4-phosphate 5-kinase (PIP5K) cDNA (AtP5K1) from Arabidopsis thaliana. By the application of cell permeabilization and short-term nonequilibrium labelling we show that expression of AtP5K1 in Baculovirus-infected insect (Spodoptera frugiperda) cells directs synthesis of PtdIns(4,5)P2 and PtdIns(3,4,5)P3. The same phosphoinositides were produced by isolated whole-cell membrane fractions of AtP5K1-expressing insect cells. Their synthesis was not affected by adding defined precursor lipids, that is PtdIns(3)P, PtdIns(4)P, PtdIns(3,4)P2, or PtdIns(4,5)P2, in excess, indicating that substrates for the plant enzyme were not limiting in vivo. Enzymatic dissection of lipid headgroups revealed that AtP5K1-directed synthesis of PtdIns(4,5)P2 and PtdIns(3,4,5)P3 proceeds via 5-phosphorylation of precursors. Analysis of promoter-reporter gene (beta-glucuronidase) fusions in transgenic plants revealed that expression of the AtP5K1 gene is strongest in vascular tissues of leaves, flowers, and roots, namely in cells of the lateral meristem, that is the procambium. Single-cell sampling of sap from flower stem meristem tissue and neighbouring phloem cells, when coupled to reverse transcriptase--polymerase chain reaction, confirmed preferential expression of AtP5K1 in procambial tissue. We hypothesize that AtP5K1, like animal and yeast PIP5K, may be involved in the control of cell proliferation.
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Affiliation(s)
- S Elge
- Max-Planck-Insitute of Molecular Plant Physiology, Am Mühlenberg 1, D-14476 Golm, Germany
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17
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Row PE, Reaves BJ, Domin J, Luzio JP, Davidson HW. Overexpression of a rat kinase-deficient phosphoinositide 3-kinase, Vps34p, inhibits cathepsin D maturation. Biochem J 2001; 353:655-61. [PMID: 11171063 PMCID: PMC1221612 DOI: 10.1042/0264-6021:3530655] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Lipid kinases and their phosphorylated products are important regulators of many cellular processes, including intracellular membrane traffic. The best example of this is provided by the class III phosphoinositide 3-kinase (PI-3K), Vps34p, which is required for correct targeting of newly synthesized carboxypeptidase Y to the yeast vacuole. A probable mammalian Vps34p orthologue has been previously identified, but its function in the trafficking of lysosomal enzymes has not been resolved. To investigate the possible role(s) of mammalian Vps34p in protein targeting to lysosomes, we have cloned the rat orthologue and overexpressed a kinase-deficient mutant in HeLa cells. Expression of the mutant protein inhibited both maturation of procathepsin D and basal secretion of the precursor. In contrast wortmannin, which also inhibited maturation, caused hypersecretion of the precursor. We propose that mammalian Vps34p plays a direct role in targeting lysosomal enzyme precursors to the endocytic pathway in an analogous fashion to its role in the fusion of early endocytic vesicles with endosomes. We further suggest that inhibition of a wortmannin-sensitive enzyme, other than mammalian Vps34p, is responsible for the failure to recycle unoccupied mannose 6-phosphate receptors to the trans-Golgi network, and consequent hypersecretion of lysosomal enzyme precursors observed in the presence of this drug.
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Affiliation(s)
- P E Row
- Wellcome Trust Centre for the Study of Molecular Mechanisms in Disease, University of Cambridge, Addenbrookes Hospital, Hills Road, Cambridge CB2 2XY, UK
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18
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Bunney TD, Watkins PA, Beven AF, Shaw PJ, Hernandez LE, Lomonossoff GP, Shanks M, Peart J, Drobak BK. Association of phosphatidylinositol 3-kinase with nuclear transcription sites in higher plants. THE PLANT CELL 2000; 12:1679-88. [PMID: 11006340 PMCID: PMC149078 DOI: 10.1105/tpc.12.9.1679] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The kinases responsible for phosphorylation of inositol-containing lipids are essential for many aspects of normal eukaryotic cell function. Genetic and biochemical studies have established that the phosphatidylinositol (PtdIns) 3-kinase encoded by the yeast VPS34 gene is essential for the efficient sorting and delivery of proteins to the vacuole; the kinase encoded by the human VPS34 homolog has been equally implicated in the control of intracellular vesicle traffic. The plant VPS34 homolog also is required for normal growth and development, and although a role for PtdIns 3-kinase in vesicle trafficking is likely, it has not been established. In this study, we have shown that considerable PtdIns 3-kinase activity is associated with the internal matrix of nuclei isolated from carrot suspension cells. Immunocytochemical and confocal laser scanning microscopy studies using the monoclonal antibody JIM135 (John Innes Monoclonal 135), raised against a truncated version of the soybean PtdIns 3-kinase, SPI3K-5p, revealed that this kinase appears to have a distinct and punctate distribution within the plant nucleus and nucleolus. Dual probing of root sections with JIM135 and anti-bromo-UTP antibodies, after in vitro transcription had been allowed to proceed in the presence of bromo-UTP, showed that SPI3K-5p associates with active nuclear and nucleolar transcription sites. These findings suggest a possible link between PtdIns 3-kinase activity and nuclear transcription in plants.
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Affiliation(s)
- T D Bunney
- John Innes Centre, Norwich Research Park, Colney, NR4 7UH, United Kingdom
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19
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Eck R, Bruckmann A, Wetzker R, Künkel W. A phosphatidylinositol 3-kinase of Candida albicans: molecular cloning and characterization. Yeast 2000; 16:933-44. [PMID: 10870104 DOI: 10.1002/1097-0061(200007)16:10<933::aid-yea591>3.0.co;2-c] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
A phosphatidylinositol (PI) 3-kinase gene (CaVPS34) of the human pathogenic yeast Candida albicans was cloned by a PCR-based homology approach. The open reading frame encodes a 1020 amino acid protein with a calculated molecular weight of 118 kDa and a relative isoelectric point of 6.9. It shares 47% sequence identity with Saccharomyces cerevisiae Vps34p. Southern pattern indicated that CaVPS34 is probably present as a single copy gene per haploid genome in C. albicans. We localized the CaVPS34 gene on chromosome 1. Under all conditions tested a major CaVPS34 transcript of approximately 3. 5 kb could be detected. CaVPS34 mRNA levels increased during exponential growth up to 12-fold followed by a decline upon entry into stationary phase. The size of a 6xHis tag-CaVps34p fusion protein purified from Escherichia coli is in agreement with the calculated molecular mass of CaVps34p. It exhibits in vitro PI 3-kinase activity and produces only phosphatidylinositol 3-phosphate. The CaVPS34 gene under the control of its own promoter were not able to complement the temperature-sensitive growth of S. cerevisiae vps34. However, overexpression of CaVPS34 was sufficient to rescue the temperature-sensitive vps34 phenotype, suggesting a functional conservation in C. albicans.
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Affiliation(s)
- R Eck
- Hans-Knöll-Institute for Natural Products Research, Department of Infection Biology, Beutenbergstrasse 11, D-07745 Jena, Germany.
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Murray J, Wilson L, Kellie S. Phosphatidylinositol-3′ kinase-dependent vesicle formation in macrophages in response to macrophage colony stimulating factor. J Cell Sci 2000; 113 Pt 2:337-48. [PMID: 10633084 DOI: 10.1242/jcs.113.2.337] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Treatment of the BAC1.2F5 macrophage cell line with Macrophage Colony Stimulating Factor (M-CSF) resulted in a rapid induction of vesiculation that was reminiscent of macropinocytosis. Time-lapse micrography showed that these vesicles initiated as small vesicles at the cell periphery, but grew in size and migrated with time to a perinuclear localisation after growth factor stimulation. Immunofluorescence showed that the M-CSF receptor (c-fms) associated with the small vesicles and also the larger phase-bright vesicles. Treatment with two distinct inhibitors showed that the rapid initiation of vesicle formation was not dependent on phosphatidylinositol-3′ (PI-3) kinase activity; however, the subsequent maintenance, maturation and translocation of the large, phase-bright, c-fms-containing vesicles was dependent on PI-3 kinase activity. The inhibitors could also reverse the further maturation of preformed vesicles. The inhibition of vesicle trafficking and maturation correlated with ablation of M-CSF-induced PI-3 kinase activity associated with p110(alpha). These data demonstrate a role for PI-3 kinase in vesicle trafficking and maintenance. PI-3 kinase activity was also necessary for the macropinocytotic response in macrophages, a process that is essential for efficient antigen processing and presentation in macrophage-like cells.
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Affiliation(s)
- J Murray
- Yamanouchi Research Institute, Littlemore Park, Oxford OX4 4XS, UK
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21
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Beitz LO, Fruman DA, Kurosaki T, Cantley LC, Scharenberg AM. SYK is upstream of phosphoinositide 3-kinase in B cell receptor signaling. J Biol Chem 1999; 274:32662-6. [PMID: 10551821 DOI: 10.1074/jbc.274.46.32662] [Citation(s) in RCA: 141] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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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22
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Siddhanta U, McIlroy J, Shah A, Zhang Y, Backer JM. Distinct roles for the p110alpha and hVPS34 phosphatidylinositol 3'-kinases in vesicular trafficking, regulation of the actin cytoskeleton, and mitogenesis. J Cell Biol 1998; 143:1647-59. [PMID: 9852157 PMCID: PMC2132989 DOI: 10.1083/jcb.143.6.1647] [Citation(s) in RCA: 134] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/1998] [Revised: 10/27/1998] [Indexed: 11/22/2022] Open
Abstract
We have examined the roles of the p85/ p110alpha and hVPS34 phosphatidylinositol (PI) 3'-kinases in cellular signaling using inhibitory isoform-specific antibodies. We raised anti-hVPS34 and anti-p110alpha antibodies that specifically inhibit recombinant hVPS34 and p110alpha, respectively, in vitro. We used the antibodies to study cellular processes that are sensitive to low-dose wortmannin. The antibodies had distinct effects on the actin cytoskeleton; microinjection of anti-p110alpha antibodies blocked insulin-stimulated ruffling, whereas anti-hVPS34 antibodies had no effect. The antibodies also had different effects on vesicular trafficking. Microinjection of inhibitory anti-hVPS34 antibodies, but not anti-p110alpha antibodies, blocked the transit of internalized PDGF receptors to a perinuclear compartment, and disrupted the localization of the early endosomal protein EEA1. Microinjection of anti-p110alpha antibodies, and to a lesser extent anti-hVPS34 antibodies, reduced the rate of transferrin recycling in CHO cells. Surprisingly, both antibodies inhibited insulin-stimulated DNA synthesis by 80%. Injection of cells with antisense oligonucleotides derived from the hVPS34 sequence also blocked insulin-stimulated DNA synthesis, whereas scrambled oligonucleotides had no effect. Interestingly, the requirement for p110alpha and hVPS34 occurred at different times during the G1-S transition. Our data suggest that different PI 3'-kinases play distinct regulatory roles in the cell, and document an unexpected role for hVPS34 during insulin-stimulated mitogenesis.
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Affiliation(s)
- U Siddhanta
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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23
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Wymann MP, Pirola L. Structure and function of phosphoinositide 3-kinases. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1436:127-50. [PMID: 9838078 DOI: 10.1016/s0005-2760(98)00139-8] [Citation(s) in RCA: 484] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Phosphoinositide kinases (PI3Ks) play an important role in mitogenic signaling and cell survival, cytoskeletal remodeling, metabolic control and vesicular trafficking. Here we summarize the structure-function relationships delineating the activation process of class I PI3Ks involving various domains of adapter subunits, Ras, and interacting proteins. The resulting product, PtdIns(3,4,5)P3, targets Akt/protein kinase B (PKB), Bruton's tyrosine kinase (Btk), phosphoinositide-dependent kinases (PDK), integrin-linked kinase (ILK), atypical protein kinases C (PKC), phospholipase Cgamma and more. Surface receptor-activated PI3Ks function in mammals, insects, nematodes and slime mold, but not yeast. While many members of the class II family have been identified and characterized biochemically, it is presently unknown how these C2-domain containing PI3Ks are activated, and which PI substrate they phosphorylate in vivo. PtdIns 3-P is produced by Vps34p/class III PI3Ks and operates via the PtdIns 3-P-binding proteins early endosomal antigen (EEA1), yeast Vac1p, Vps27p, Pip1p in lysosomal protein targeting. Besides the production of D3 phosphorylated lipids, PI3Ks have an intrinsic protein kinase activity. For trimeric GTP-binding protein-activated PI3Kgamma, protein kinase activity seems to be sufficient to trigger mitogen-activated protein kinase (MAPK). Recent disruption of PI3K genes in slime mold, Caenorhabditis elegans, Drosophila melanogaster and mice further underlines the importance of PI3K signaling systems and elucidates the role of PI3K signaling in multicellular organisms.
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Affiliation(s)
- M P Wymann
- Institute of Biochemistry, University of Fribourg, Rue du Musée 5, CH-1700 Fribourg, Switzerland.
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24
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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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25
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Ho LK, Liu D, Rozycka M, Brown RA, Fry MJ. Identification of four novel human phosphoinositide 3-kinases defines a multi-isoform subfamily. Biochem Biophys Res Commun 1997; 235:130-7. [PMID: 9196049 DOI: 10.1006/bbrc.1997.6747] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Phosphoinositide (PI) 3-kinases have critical roles in diverse cellular signalling processes and in protein trafficking. This suggests that like other intracellular signalling molecules, e.g., phospholipase C and protein kinase C, there might be a large family of PI 3-kinase isoforms with the individual members having discrete signalling roles. Reverse transcription-polymerase chain reaction methods, using degenerate oligonucleotide primers against the lipid kinase consensus region, revealed eight sequences from human cDNA containing a high degree of identity to the family of PI 3-kinases. The sequences obtained included the previously described p110 alpha, p110 beta, and p110 gamma isoforms and HsVps34. Additionally, we have identified four novel sequences which are related to PI 3-kinases. Three of the novel sequences would appear to form a distinct sub-family of PI 3-kinases. We report the expression of these novel PI 3-kinases in human tissues and in cells derived from normal breast.
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Affiliation(s)
- L K Ho
- Section of Cell Biology and Experimental Pathology, Institute of Cancer Research, Haddow Laboratories, Sutton, Surrey, United Kingdom
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26
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Weinkove D, Leevers SJ, MacDougall LK, Waterfield MD. p60 is an adaptor for the Drosophila phosphoinositide 3-kinase, Dp110. J Biol Chem 1997; 272:14606-10. [PMID: 9169420 DOI: 10.1074/jbc.272.23.14606] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The mammalian phosphoinositide 3-kinases (PI3Ks) p110alpha, beta, and delta form heterodimers with Src homology 2 (SH2) domain-containing adaptors such as p85alpha or p55(PIK). The two SH2 domains of these adaptors bind to phosphotyrosine residues (pY) found within the consensus sequence pYXXM. Here we show that a heterodimer of the Drosophila PI3K, Dp110, with an adaptor, p60, can be purified from S2 cells with a pYXXM phosphopeptide affinity matrix. Using amino acid sequence from the gel-purified protein, the gene encoding p60 was cloned and mapped to the genomic region 21B8-C1, and the exon/intron structure was determined. p60 contains two SH2 domains and an inter-SH2 domain but lacks the SH3 and breakpoint cluster region homology (BH) domains found in mammalian p85alpha and beta. Analysis of the sequence of p60 shows that the amino acids responsible for the SH2 domain binding specificity in mammalian p85alpha are conserved and predicts that the inter-SH2 domain has a coiled-coil structure. The Dp110.p60 complex was immunoprecipitated with p60-specific antisera and shown to possess both lipid and protein kinase activity. The complex was found in larvae, pupae, and adults, consistent with p60 functioning as the adaptor for Dp110 throughout the Drosophila life cycle.
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Affiliation(s)
- D Weinkove
- Ludwig Institute for Cancer Research, 91 Riding House Street, London W1P 8BT, United Kingdom
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