Binding of Elongation Factor eEF1A2 to Phosphatidylinositol 4-Kinase β Stimulates Lipid Kinase Activity and Phosphatidylinositol 4-Phosphate Generation

Eukaryotic protein translation elongation factor 1 α 2 (eEF1A2) is an oncogene that transforms mammalian cell lines and increases their tumorigenicity in nude mice. Increased expression of eEF1A2 occurs during the development of breast, ovarian, and lung cancer. Here, we report that eEF1A2 directly binds to and activates phosphatidylinositol 4-kinase III β (PI4KIIIβ), an enzyme that converts phosphatidylinositol to phosphatidylinositol 4-phosphate. Purified recombinant eEF1A2 increases PI4KIIIβ lipid kinase activity in vitro, and expression of eEF1A2 in rat and human cells is sufficient to increase overall cellular phosphatidylinositol 4-kinase activity and intracellular phosphatidylinositol 4-phosphate abundance. siRNA-mediated reduction in eEF1A2 expression concomitantly reduces phosphatidylinositol 4-kinase activity. This identifies a physical and functional relationship between eEF1A2 and PI4KIIIβ. Eukaryotic protein translation elongation factor 1 α 2 (eEF1A2) is an oncogene that transforms mammalian cell lines and increases their tumorigenicity in nude mice. Increased expression of eEF1A2 occurs during the development of breast, ovarian, and lung cancer. Here, we report that eEF1A2 directly binds to and activates phosphatidylinositol 4-kinase III β (PI4KIIIβ), an enzyme that converts phosphatidylinositol to phosphatidylinositol 4-phosphate. Purified recombinant eEF1A2 increases PI4KIIIβ lipid kinase activity in vitro, and expression of eEF1A2 in rat and human cells is sufficient to increase overall cellular phosphatidylinositol 4-kinase activity and intracellular phosphatidylinositol 4-phosphate abundance. siRNA-mediated reduction in eEF1A2 expression concomitantly reduces phosphatidylinositol 4-kinase activity. This identifies a physical and functional relationship between eEF1A2 and PI4KIIIβ. eEF1A2 2The abbreviations used are: eEF1A2, eukaryotic elongation factor 1α 2; PI4K, phosphatidylinositol 4-kinase; PI4P, phosphatidylinositol 4-phosphate; siRNA, short interfering RNA; GFP, green fluorescent protein; C/EBPβ, CAAT/enhancer-binding protein β; GST, glutathione S-transferase; MOI, multiplicity of infection; PBS, phosphate-buffered saline; PI(3,4,5)P3, phosphatidylinositol 3,4,5-trisphosphate. is one of two members of the eEF1A family of proteins (eEF1A1 and eEF1A2). During protein translation elongation, eEF1A proteins bind amino-acylated tRNA and facilitate their recruitment to the ribosome (1Hershey J.W. Annu. Rev. Biochem. 1991; 60: 717-755Crossref PubMed Scopus (843) Google Scholar). Aside from their canonical role in protein translation, eEF1A proteins have other functions, including binding actin and inducing rearrangements of the actin and tubulin cytoskeleton (2Condeelis J. Trends Biochem. Sci. 1995; 20: 169-170Abstract Full Text PDF PubMed Scopus (258) Google Scholar, 3Shiina N. Gotoh Y. Kubomura N. Iwamatsu A. Nishida E. Science. 1994; 266: 282-285Crossref PubMed Scopus (229) Google Scholar). The inactivation of the mouse eEF1A2 homolog, Eef1a2, leads to immunodeficiency and death by 30 days of age (4Shultz L.D. Sweet H.O. Davisson M.T. Coman D.R. Nature. 1982; 297: 402-404Crossref PubMed Scopus (81) Google Scholar, 5Chambers D.M. Peters J. Abbott C.M. Proc. Natl. Acad. Sci. U. S. A. 1998; 95: 4463-4468Crossref PubMed Scopus (128) Google Scholar). Mammalian eEF1A2 mRNA can be detected only in normal mammalian heart, brain, and skeletal muscle tissues (6Knudsen S.M. Frydenberg J. Clark B.F. Leffers H. Eur. J. Biochem. 1993; 215: 549-554Crossref PubMed Scopus (138) Google Scholar, 7Lee S. Wolfraim L.A. Wang E. J. Biol. Chem. 1993; 268: 24453-24459Abstract Full Text PDF PubMed Google Scholar, 8Kahns S. Lund A. Kristensen P. Knudsen C.R. Clark B.F. Cavallius J. Merrick W.C. Nucleic Acids Res. 1998; 26: 1884-1890Crossref PubMed Scopus (93) Google Scholar). However, high levels of eEF1A2 protein and mRNA are observed in a 30-60% fraction of ovarian, breast, and lung tumors (9Anand N. Murthy S. Amann G. Wernick M. Porter L.A. Cukier I.H. Collins C. Gray J.W. Diebold J. Demetrick D.J. Lee J.M. Nat. Genet. 2002; 31: 301-305Crossref PubMed Scopus (212) Google Scholar, 10Kulkarni G. Turbin D.A. Amiri A. Jeganathan S. Andrade-Navarro M.A. Wu T.D. Huntsman D.G. Lee J.M. Breast Cancer Res. Treat. 2006; (in press)Google Scholar, 11Li R. Wang H. Bekele B.N. Yin Z. Caraway N.P. Katz R.L. Stass S.A. Jiang F. Oncogene. 2006; 25: 2628-2635Crossref PubMed Scopus (109) Google Scholar, 12Tomlinson V.A. Newbery H.J. Wray N.R. Jackson J. Larionov A. Miller W.R. Dixon J.M. Abbott C.M. BMC Cancer. 2005; 5: 113-119Crossref PubMed Scopus (119) Google Scholar). We have previously reported that eEF1A2 has transforming properties; ectopic expression of wild type human eEF1A2 in mammalian cells enables anchorage-independent growth and enhances tumorigenicity in nude mice (9Anand N. Murthy S. Amann G. Wernick M. Porter L.A. Cukier I.H. Collins C. Gray J.W. Diebold J. Demetrick D.J. Lee J.M. Nat. Genet. 2002; 31: 301-305Crossref PubMed Scopus (212) Google Scholar). Thus, eEF1A2 has an important role in promoting tumor development. However, the mechanism by which eEF1A2 promotes oncogenicity remains unclear. It has previously been reported that an eEF1A-like protein purified from carrots, PIK-A49, binds and activates carrot phosphatidylinositol 4-kinase (PI4K) (13Yang W. Burkhart W. Cavallius J. Merrick W.C. Boss W.F. J. Biol. Chem. 1993; 268: 392-398Abstract Full Text PDF PubMed Google Scholar, 14Yang W. Boss W.F. J. Biol. Chem. 1994; 269: 3852-3857Abstract Full Text PDF PubMed Google Scholar). This suggests an important relationship between translation elongation and phosphatidylinositol generation. Phosphatidylinositols are negatively charged, membrane-bound phospholipids that serve as regulators of multiple signaling pathways (15Carpenter C.L. Cantley L.C. Biochemistry. 1990; 29: 11147-11156Crossref PubMed Scopus (296) Google Scholar, 16Fruman D.A. Meyers R.E. Cantley L.C. Annu. Rev. Biochem. 1998; 67: 481-507Crossref PubMed Scopus (1319) Google Scholar, 17Meijer H.J. Munnik T. Annu. Rev. Plant Biol. 2003; 54: 265-306Crossref PubMed Scopus (485) Google Scholar, 18Overduin M. Cheever M.L. Kutateladze T.G. Mol. Interv. 2001; 1: 150-159PubMed Google Scholar). Phosphatidylinositols are composed of an inositol ring covalently bound to a lipid phosphatidic acid backbone by a phosphodiester bond at the inositol D1 carbon. Inositol phosphorylation occurs at the D3, D4, or D5 carbons. Specific kinase families are responsible for phosphorylation at each of these sites. Phosphatidylinositol 3-kinases, PI4K, and phosphatidylinositol 5-kinases phosphorylate the D3, D4, and D5 inositol carbons, respectively (15Carpenter C.L. Cantley L.C. Biochemistry. 1990; 29: 11147-11156Crossref PubMed Scopus (296) Google Scholar, 16Fruman D.A. Meyers R.E. Cantley L.C. Annu. Rev. Biochem. 1998; 67: 481-507Crossref PubMed Scopus (1319) Google Scholar, 17Meijer H.J. Munnik T. Annu. Rev. Plant Biol. 2003; 54: 265-306Crossref PubMed Scopus (485) Google Scholar). PIK-A49 showed in vitro translation elongation factor activity and an ability to activate in vitro PI4K lipid kinase activity (13Yang W. Burkhart W. Cavallius J. Merrick W.C. Boss W.F. J. Biol. Chem. 1993; 268: 392-398Abstract Full Text PDF PubMed Google Scholar, 14Yang W. Boss W.F. J. Biol. Chem. 1994; 269: 3852-3857Abstract Full Text PDF PubMed Google Scholar). However, PIK-A49 does not have complete amino acid sequence identity with wild-type carrot eEF1A and has yet to be cloned as a full-length cDNA. It is therefore unclear whether PIK-A49 is a bona fide eEF1A protein; nor is it known whether wild-type carrot eEF1A or eEF1A proteins from nonplant species participate in PI4K activation. In addition, there are three identified subfamilies of PI4K proteins, phosphatidylinositol 4-kinase III α, phosphatidylinositol 4-kinase III β (PI4KIIIβ), and PI4KII (19Balla A. Balla T. Trends Cell Biol. 2006; 16: 351-361Abstract Full Text Full Text PDF PubMed Scopus (282) Google Scholar, 20Heilmeyer Jr., L.M. Vereb Jr., G. Vereb G. Kakuk A. Szivak I. IUBMB Life. 2003; 55: 59-65Crossref PubMed Scopus (53) Google Scholar), and it is unclear which PI4K isoform(s) is activated by PIK-A49 or other eEF1A proteins. Moreover, in vitro PI4K activation by PIK-A49/eEF1A has unknown physiological significance. Here we report that human eEF1A2 can directly bind and activate PI4KIIIβ. Ectopic expression of eEF1A2 in rodent and human cells increases overall PI4K activity and cellular phosphatidylinositol 4-phosphate (PI4P) generation. Furthermore, eEF1A2 ablation reduces endogenous PI4K activity. This suggests that eEF1A2 is a physiological regulator of PI4KIIIβ. Cell Lines—MCF7, BT549, and Rat2 cells were purchased from the American Type Culture Collection (Manassas, VA) and grown according to their instructions. Adenoviral Vectors— eEF1A2 was subcloned into the pShuttle-IRES plasmid (EcoRV/XhoI) with a FLAG epitope tag. eEF1A2 and GFP virus were manufactured by the Adenoviral Core Facility of the University of Ottawa. For viral transduction, BT549 and Rat2 cells were infected with Ad-eEF1A2 or Ad-GFP at a multiplicity of infection (MOI) of 200 (BT549) or 500 (Rat2) in complete media. Cells were incubated with virus for a minimum of 24 h. Antibodies—Antibodies used for experiments were as follows: human PI4KIIIβ (Upstate Cell Signaling Solutions, Charlottesville, VA), β-actin (Sigma), horseradish peroxidase-conjugated goat anti-mouse IgG (Upstate Cell Signaling Solutions), and horseradish peroxidase-conjugated anti-rabbit IgG, (Cell Signaling Technology, Danvers, MA). The generation of the rabbit polyclonal eEF1A2 antibody and its validation in Western blotting, immunoprecipitation, and immunohistochemistry is described elsewhere (10Kulkarni G. Turbin D.A. Amiri A. Jeganathan S. Andrade-Navarro M.A. Wu T.D. Huntsman D.G. Lee J.M. Breast Cancer Res. Treat. 2006; (in press)Google Scholar). GST Fusion Proteins— eEF1A2 cDNA was cloned into the EcoRI/NotI site of pGEX-4T2 (Amersham Biosciences). GST-eEF1A2 was transformed into Escherichia coli BL21DE3 and grown in Luria-Bertani media with 100 μg/ml ampicillin to A600 ∼0.7. 0.5 mm isopropyl 1-thio-β-d-galactopyranoside was added for 2 h at 25 °C. Bacteria were lysed in 25 mm HEPES, pH 7.9, 100 mm KCl, 2 mm EDTA, 20% glycerol, 2 mm dithiothreitol, and 1× protease inhibitor mixture (Roche Applied Science). Glutathione-Sepharose 4B beads (Amersham Biosciences) were equilibrated in lysis buffer and mixed with PI4KIIIβ in was a of T. Balla A. Vereb G. H. T. P. Jr., L.M. M. Res. PubMed Scopus Google Scholar, T. Balla T. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar). The protein was purified as described T. Balla T. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar). was a from N. of the GST 100 of GST-eEF1A2 was incubated with 1 of (Amersham Biosciences) in 1× at PI4KIIIβ was by 100 of with 1 of (Amersham Biosciences) in mm mm 1 mm EDTA, 1 mm dithiothreitol, pH at °C. of recombinant protein in PBS, at in the was added to of kinase buffer mm EDTA, 30 mm pH 100 mm 2 mm and mm as in the and of mm of and incubated for The was by the of of 1 were by of a were for at of the were and in a to were with mm in for 1 h and to were activated by for 1 h at °C. Phosphatidylinositol were purchased from were and in of were in and were the of and were the For cell recombinant eEF1A2 and the cell were added in a of eEF1A2 PI4KIIIβ were incubated in and with 30 mm in pH at were by the of acid at a to the were to a of with in and in a 100 mm buffer as previously described R. R.E. in Scholar). Cell and cells were grown to in cell Cells were lysed by in buffer mm mm mm KCl, mm EDTA, 1 mm 1 mm μg/ml 1 mm and at for to were and protein levels were a according to the instructions. 100 of protein was with protein (Amersham Biosciences) for 1 h at of or eEF1A2 antibody to beads were added and incubated at °C. were three in PBS, and for in and the was to The of the eEF1A2 antibody to protein beads was a previously described E. Scholar). Western was according to the or as described for the eEF1A2 antibody (10Kulkarni G. Turbin D.A. Amiri A. Jeganathan S. Andrade-Navarro M.A. Wu T.D. Huntsman D.G. Lee J.M. Breast Cancer Res. Treat. 2006; (in press)Google Scholar). For Western blotting, cells were lysed in buffer mm pH 1 mm EDTA, pH mm 1 mm 1 mm μg/ml in and 1 mm in of the eEF1A2 are and The was purchased from were according to the instructions. Rat2 and BT549 cells were with (9Anand N. Murthy S. Amann G. Wernick M. Porter L.A. Cukier I.H. Collins C. Gray J.W. Diebold J. Demetrick D.J. Lee J.M. Nat. Genet. 2002; 31: 301-305Crossref PubMed Scopus (212) Google or according to the instructions. h was and complete was The cells were and as Cells were with goat for 30 at and antibody was added in anti-mouse was added at in for 30 eEF1A2 was detected with a antibody in PBS, 1 by an goat anti-mouse IgG in PBS, 1 Cell were with for at were with a and or an was with the eEF1A2 PI4KIIIβ whether eEF1A2 activate we purified recombinant GST-eEF1A2 and The proteins were with and their GST of the purified proteins is in The of wild-type eEF1A2 is and that of PI4KIIIβ is We whether eEF1A2 increase PI4K activity in cell in the of GST-eEF1A2 to a cell of BT549 cells in vitro generation with the of GST or GST to the is in the of PI4KIIIβ has previously been reported to be in in vitro lipid kinase A. Vereb G. H. T. P. Jr., L.M. M. Res. PubMed Scopus Google Scholar, T. Balla T. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar). in was in vitro, and its kinase activity was by that we are the lipid kinase activity of a type III PI4K, the family of to which PI4KIIIβ whether purified eEF1A2 directly activate we added recombinant eEF1A2 to purified PI4KIIIβ in eEF1A2 PI4KIIIβ lipid kinase activity in a PI4KIIIβ activity was eEF1A2 is to activate a 100 of PI4KIIIβ. of PI4KIIIβ activity was observed in the of In to eEF1A2 PI4KIIIβ we the PI4KIIIβ and for phosphatidylinositol with and as the in eEF1A2 the of PI4KIIIβ from to This of was in the increase of from to The PI4KIIIβ was eEF1A2 whether eEF1A2 directly with PI4KIIIβ in a in purified PI4KIIIβ was by and eEF1A2 was by PI4KIIIβ nor eEF1A2 was by GST We the of We incubated recombinant eEF1A2 and PI4KIIIβ and the in 1 h of of the added PI4KIIIβ and eEF1A2 were in a with an of The of the was and a of was detected at of to the 30 eEF1A2 has an of and that of PI4KIIIβ is The of the that eEF1A2 and PI4KIIIβ with a eEF1A2 nor PI4KIIIβ their We were to protein with a that one each of eEF1A2 or PI4KIIIβ not eEF1A2 with PI4KIIIβ in Mammalian Cell whether eEF1A2 and PI4KIIIβ in we identified mammalian cells that In and eEF1A2 mRNA and protein expression only in the tissues of the heart, brain, and skeletal muscle (6Knudsen S.M. Frydenberg J. Clark B.F. Leffers H. Eur. J. Biochem. 1993; 215: 549-554Crossref PubMed Scopus (138) Google Scholar, 7Lee S. Wolfraim L.A. Wang E. J. Biol. Chem. 1993; 268: 24453-24459Abstract Full Text PDF PubMed Google Scholar, 8Kahns S. Lund A. Kristensen P. Knudsen C.R. Clark B.F. Cavallius J. Merrick W.C. Nucleic Acids Res. 1998; 26: 1884-1890Crossref PubMed Scopus (93) Google Scholar). We have observed eEF1A2 expression in cell lines (10Kulkarni G. Turbin D.A. Amiri A. Jeganathan S. Andrade-Navarro M.A. Wu T.D. Huntsman D.G. Lee J.M. Breast Cancer Res. Treat. 2006; (in press)Google Scholar). in we detected eEF1A2 protein expression in the human cell in BT549 cells nor in the Rat2 rat cell We used to whether wild-type eEF1A2 and PI4KIIIβ in We used cell lysis for these in eEF1A2 with and PI4KIIIβ with protein bound to the FLAG antibody is only we that of endogenous PI4KIIIβ with eEF1A2 lysis of eEF1A2 was with PI4KIIIβ. PI4KIIIβ and eEF1A2 have been previously reported to be PI4KIIIβ has in the (9Anand N. Murthy S. Amann G. Wernick M. Porter L.A. Cukier I.H. Collins C. Gray J.W. Diebold J. Demetrick D.J. Lee J.M. Nat. Genet. 2002; 31: 301-305Crossref PubMed Scopus (212) Google Scholar, A. Balla T. Trends Cell Biol. 2006; 16: 351-361Abstract Full Text Full Text PDF PubMed Scopus (282) Google Scholar, 20Heilmeyer Jr., L.M. Vereb Jr., G. Vereb G. Kakuk A. Szivak I. IUBMB Life. 2003; 55: 59-65Crossref PubMed Scopus (53) Google Scholar). We to eEF1A2 and PI4KIIIβ were to between PI4KIIIβ and eEF1A2 is by the of the two proteins and the to which the two proteins the of eEF1A2 that with in PI4KIIIβ that in eEF1A2 to PI4K whether eEF1A2 expression was sufficient to increase PI4K activity in mammalian we used an to eEF1A2 in BT549 and Rat2 cell eEF1A2 a of virus infection PI4K lipid phosphorylation was between cells and infected with GFP However, the to 200 cellular PI4K activity in cells to infected with GFP infection of Rat2 cells with the eEF1A2 PI4K activity to GFP Adenoviral infection by eEF1A2 does not PI4KIIIβ protein levels Thus, eEF1A2 expression can increase PI4K activity in these mammalian cell eEF1A2 a PI4K whether eEF1A2 a physiological role in PI4K we eEF1A2 protein levels in cells eEF1A2 For we two in eEF1A2 protein levels with cells with a or eEF1A2 The siRNA-mediated in eEF1A2 protein levels to a in PI4K activity to eEF1A2 whether eEF1A2 increase intracellular abundance. we Rat2 and BT549 cells with an eEF1A2 plasmid and these cells with an antibody for in BT549 and Rat2 cells eEF1A2 showed that is in of eEF1A2 The increase in occurs the with GFP levels the increase in we each into expression of the protein and in cells from each in cells or high levels of eEF1A2 each have a of that or eEF1A2 This increase of generation in Rat2 and BT549 cells with GFP generation. Thus, eEF1A2 expression increases intracellular abundance. Phosphatidylinositol are in pathways that cell and C. H. M. 2003; PubMed Scopus Google Scholar). In we that eEF1A2 binds increases its in vitro lipid kinase activity and can increase intracellular generation in rat and human We that purified eEF1A2 can increase recombinant PI4KIIIβ activity in other PI4KIIIβ have been previously factor and P. G. Balla A. C. J. A. Balla T. J. Biol. Chem. 2001; Full Text Full Text PDF PubMed Scopus Google Scholar, A. P. Meyers R. P. G. C. A. M.A. Nat. Cell Biol. 1: PubMed Scopus Google Scholar). a PI4KIIIβ activation A. P. Meyers R. P. G. C. A. M.A. Nat. Cell Biol. 1: PubMed Scopus Google Scholar). in cells PI4KIIIβ Y. S. I. A. R. J. 2003; PubMed Scopus Google Scholar). we that PI4K activity and that ectopic eEF1A2 expression it is that eEF1A2 is a and physiological PI4KIIIβ In human the of PI4K activity is with the and the of the and Jr., L.M. Vereb Jr., G. Vereb G. Kakuk A. Szivak I. IUBMB Life. 2003; 55: 59-65Crossref PubMed Scopus (53) Google Scholar, G. R. M. J. S. M.A. Nucleic Acids Res. 2003; 31: PubMed Scopus Google Scholar, Biochem. J. 2001; PubMed Scopus Google Scholar, D.M. Eur. J. Google Scholar, J. F. F. P. Proc. Natl. Acad. Sci. U. S. A. 2003; PubMed Scopus Google Scholar). are known to and be in and J. F. F. P. Proc. Natl. Acad. Sci. U. S. A. 2003; PubMed Scopus Google Scholar). The of mammalian has been in A. M. Mol. Biol. PubMed Scopus Google Scholar, F. I. C. J. 1994; PubMed Scopus Google Scholar, H. J. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar, J. C. A. Res. 2005; 5: PubMed Scopus Google Scholar, V.A. A. N. C. Mol. Biol. 2005; 16: PubMed Scopus Google Scholar, C. P. Nat. Cell Biol. 1: PubMed Scopus Google Scholar). the protein by is for normal and and A. M. Mol. Biol. PubMed Scopus Google Scholar, F. I. C. J. 1994; PubMed Scopus Google Scholar, H. J. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar, J. C. A. Res. 2005; 5: PubMed Scopus Google Scholar, V.A. A. N. C. Mol. Biol. 2005; 16: PubMed Scopus Google Scholar, C. P. Nat. Cell Biol. 1: PubMed Scopus Google Scholar). to the and the F. I. C. J. 1994; PubMed Scopus Google Scholar, C. P. Nat. Cell Biol. 1: PubMed Scopus Google Scholar). cells a in of J. C. A. Res. 2005; 5: PubMed Scopus Google Scholar). Mammalian PI4KIIIβ is in the J. A. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar, M.A. A. J. Biol. Chem. 2002; Full Text Full Text PDF PubMed Scopus Google Scholar), protein is in the However, we have not eEF1A2 protein in the and we have observed in cells not This suggests that the of eEF1A2 to increase is of cell PI4K is observed in the R.E. Boss W.F. Rev. PubMed Google Scholar), and we that eEF1A2 expression increases generation the The mechanism by which eEF1A2 activates PI4KIIIβ is eEF1A proteins bind and and bind have not been to have activity or other to covalently proteins. Thus, it is that eEF1A2 PI4KIIIβ activity by eEF1A2 expression does not increase PI4KIIIβ protein levels it is that eEF1A2 expression increases cellular generation by the of PI4KIIIβ We that between eEF1A2 and PI4KIIIβ leads to a in PI4KIIIβ that increases its activity. This is with that eEF1A2 increases the overall PI4KIIIβ and PI4KIIIβ a kinase the of remains an we not that eEF1A2 is a phosphatidylinositol kinase We have been to physical between eEF1A2 and phosphatidylinositol 3-kinases, nor have we observed activation of kinase by eEF1A2 not in vitro that eEF1A2 and PI4KIIIβ bind in a and the of recombinant eEF1A2 and PI4KIIIβ are to with each However, to a of recombinant eEF1A2 is to increase in vitro PI4KIIIβ activity. Thus, it is that of eEF1A2 its ability to activate PI4KIIIβ. and Boss W. Boss W.F. J. Biol. Chem. 1994; 269: 3852-3857Abstract Full Text PDF PubMed Google showed that of PIK-A49 it from PI4KIIIβ and that activation be by in vitro phosphorylation of PIK-A49 by a protein The of of eEF1A2 its ability to PI4KIIIβ activity is However, of eEF1A2 have yet been and that of eEF1A2 is not for PI4KIIIβ activation. only a fraction of eEF1A2 is in a with PI4KIIIβ in cells of eEF1A2 cellular and therefore generation. eEF1A2 is in a 30-60% fraction of breast, and lung tumors (9Anand N. Murthy S. Amann G. Wernick M. Porter L.A. Cukier I.H. Collins C. Gray J.W. Diebold J. Demetrick D.J. Lee J.M. Nat. Genet. 2002; 31: 301-305Crossref PubMed Scopus (212) Google Scholar, 10Kulkarni G. Turbin D.A. Amiri A. Jeganathan S. Andrade-Navarro M.A. Wu T.D. Huntsman D.G. Lee J.M. Breast Cancer Res. Treat. 2006; (in press)Google Scholar, 11Li R. Wang H. Bekele B.N. Yin Z. Caraway N.P. Katz R.L. Stass S.A. Jiang F. Oncogene. 2006; 25: 2628-2635Crossref PubMed Scopus (109) Google Scholar, 12Tomlinson V.A. Newbery H.J. Wray N.R. Jackson J. Larionov A. Miller W.R. Dixon J.M. Abbott C.M. BMC Cancer. 2005; 5: 113-119Crossref PubMed Scopus (119) Google Scholar). We have previously reported that eEF1A2 has transforming (9Anand N. Murthy S. Amann G. Wernick M. Porter L.A. Cukier I.H. Collins C. Gray J.W. Diebold J. Demetrick D.J. Lee J.M. Nat. Genet. 2002; 31: 301-305Crossref PubMed Scopus (212) Google and that its inactivation in mice increases M. A. Lee J.M. Cell 1998; PubMed Scopus Google Scholar). This identifies eEF1A2 as an important human We that eEF1A2 activates PI4K activation and generation. that eEF1A2 expression is sufficient to increase PI4K activity and levels that high eEF1A2 levels in tumors leads to an overall increase in cellular We that of increase the of and of these phospholipids are that actin intracellular and (15Carpenter C.L. Cantley L.C. Biochemistry. 1990; 29: 11147-11156Crossref PubMed Scopus (296) Google Scholar, 20Heilmeyer Jr., L.M. Vereb Jr., G. Vereb G. Kakuk A. Szivak I. IUBMB Life. 2003; 55: 59-65Crossref PubMed Scopus (53) Google Scholar, T. 1998; PubMed Scopus Google Scholar, T. Jr., L.M. Eur. J. Biochem. 1998; PubMed Scopus (109) Google Scholar, V.A. 1: PubMed Scopus Google Scholar, H. H. A. T. Res. PubMed Scopus Google Scholar, 2001; 1: Full Text Full Text PDF PubMed Scopus Google Scholar). to be PI(3,4,5)P3, the of which cell and cell phosphatidylinositol activity has been to be the in the of PI(3,4,5)P3, not be the in tumors that have high phosphatidylinositol activity of the kinase or have in the and lipid R. Cell Biol. 2005; PubMed Scopus Google Scholar). In tumors with phosphatidylinositol or PI4K activity be to increase overall and activate This is with a report by C. H. J. Cantley F. J. 2006; 25: PubMed Scopus Google Scholar), that the phosphatidylinositol by the is sufficient to activate a kinase activity is J. Cell Biol. PubMed Scopus Google Scholar). PI4K has been reported to activate nor have PI4K been reported to be transforming or to be during However, has not been eEF1A proteins have a ability to bind and (2Condeelis J. Trends Biochem. Sci. 1995; 20: 169-170Abstract Full Text PDF PubMed Scopus (258) Google Scholar, 3Shiina N. Gotoh Y. Kubomura N. Iwamatsu A. Nishida E. Science. 1994; 266: 282-285Crossref PubMed Scopus (229) Google Scholar). It has been that eEF1A2 the protein translation to actin cytoskeleton we that eEF1A2 directly binds it is that eEF1A2 protein translation to phosphatidylinositol generation and the actin In we have identified eEF1A2 as a of PI4KIIIβ. Ectopic expression of eEF1A2 increases cellular PI4K activity and increases cellular abundance. Furthermore, siRNA-mediated eEF1A2 inactivation PI4K activity. This is with the that eEF1A2 and PI4K We that PI4KIIIβ activation has an important role in and We for with the fluorescent for with the for with the lipid kinase and Amiri for the eEF1A2 and for GST-eEF1A2 and the eEF1A2 We T. Balla for the PI4KIIIβ and for the We and for of the

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