This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Bagaglio, D. M. Articles by Hait, W. N. Search for Related Content PubMed PubMed Citation Articles by Bagaglio, D. M. Articles by Hait, W. N.

Phosphorylation of Elongation Factor 2 in Normal and Malignant Rat Glial Cells¹

Departments of Pharmacology and Internal Medicine [D. M. B., W. N. H.], Cancer Institute of New Jersey, Robert Wood Johnson Medical School, Piscataway, New Jersey 08854-5638; Departments of Medicine [E. H. C. C., F. S. G.] and Cell Biology [F. S. G.], Yale University School of Medicine, New Haven, Connecticut 06510; and the Department of Molecular and Cellular Neuroscience [K. M., A. C. N.], Rockefeller University, New York, New York 10021

Certain calmodulin (CaM)-dependent protein kinases phosphorylate substrates have been implicated in regulating cellular proliferation. In this study, CaM-dependent phosphorylation has been examined in normal and tumor tissue from rat brain to determine whether differences exist. Using in vitro phosphorylation reactions, we compared endogenous substrates for Ca²⁺/CaM-dependent protein kinases in rat brain white matter (RBWM), a tissue rich in normal glia, to those of C₆ rat glioma cells. A major phosphoprotein having a M_r of 100,000 was observed in proliferating C₆ cells that was not present in RBWM or in nonproliferating cells. Phosphorylation was stimulated by Ca²⁺ and CaM and inhibited by trifluoperazine. An antibody to elongation factor 2 (EF-2) immunoprecipitated the M_r 100,000 protein from C₆ cells. EF-2 was present in RBWM but was not phosphorylated. Homogenates of RBWM did not phosphorylate exogenous EF-2, which suggested the absence of CaM kinase III activity in normal glial tissue. Furthermore, the addition of purified, exogenous CaM kinase III to homogenates of RBWM resulted in EF-2 phosphorylation. These data demonstrate that a basal level of EF-2 phosphorylation exists in proliferating glioma cells that is markedly diminished or absent in normal glial tissue and is due to the activity of CaM kinase III.

¹ This work was supported by grants from the National Cancer Institute (CA 09085, CA 43888, and CA 08341) and the American Cancer Society (CH 49507). W. N. H. is a Burroughs-Wellcome Scholar in Clinical Pharmacology.

² To whom requests for reprints should be addressed, at the Cancer Institute of New Jersey, Robert Wood Johnson Medical School, CABM Building, 679 Hoes Lane, Piscataway, NJ 08854-5638.

Received 12/ 3/92. Accepted 3/12/93.

This article has been cited by other articles:

				H. Wu, J.-M. Yang, S. Jin, H. Zhang, and W. N. Hait Elongation factor-2 kinase regulates autophagy in human glioblastoma cells. Cancer Res., March 15, 2006; 66(6): 3015 - 3023. [Abstract] [Full Text] [PDF]

				S. Arora, J.-M. Yang, and W. N. Hait Identification of the Ubiquitin-Proteasome Pathway in the Regulation of the Stability of Eukaryotic Elongation Factor-2 Kinase Cancer Res., May 1, 2005; 65(9): 3806 - 3810. [Abstract] [Full Text] [PDF]

				Y. Nobukuni, K. Kohno, and K. Miyagawa Gene Trap Mutagenesis-based Forward Genetic Approach Reveals That the Tumor Suppressor OVCA1 Is a Component of the Biosynthetic Pathway of Diphthamide on Elongation Factor 2 J. Biol. Chem., March 18, 2005; 280(11): 10572 - 10577. [Abstract] [Full Text] [PDF]

				S. Arora, J.-M. Yang, R. Utsumi, T. Okamoto, T. Kitayama, and W. N. Hait P-Glycoprotein Mediates Resistance to Histidine Kinase Inhibitors Mol. Pharmacol., September 1, 2004; 66(3): 460 - 467. [Abstract] [Full Text] [PDF]

				S. Arora, J.-M. Yang, T. G. Kinzy, R. Utsumi, T. Okamoto, T. Kitayama, P. A. Ortiz, and W. N. Hait Identification and Characterization of an Inhibitor of Eukaryotic Elongation Factor 2 Kinase against Human Cancer Cell Lines Cancer Res., October 15, 2003; 63(20): 6894 - 6899. [Abstract] [Full Text] [PDF]

				J. Yang, J.-M. Yang, M. Iannone, W. J. Shih, Y. Lin, and W. N. Hait Disruption of the EF-2 Kinase/Hsp90 Protein Complex: A Possible Mechanism to Inhibit Glioblastoma by Geldanamycin Cancer Res., May 1, 2001; 61(10): 4010 - 4016. [Abstract] [Full Text]

				F. V. Vega, A. Vidal, U. Hellman, C. Wernstedt, and F. Dominguez Prothymosin alpha  Stimulates Ca2+-dependent Phosphorylation of Elongation Factor 2 in Cellular Extracts J. Biol. Chem., April 24, 1998; 273(17): 10147 - 10152. [Abstract] [Full Text] [PDF]

				A. G. Ryazanov, M. D. Ward, C. E. Mendola, K. S. Pavur, M. V. Dorovkov, M. Wiedmann, H. Erdjument-Bromage, P. Tempst, T. G. Parmer, C. R. Prostko, et al. Identification of a new class of protein kinases represented by eukaryotic elongation factor-2 kinase PNAS, May 13, 1997; 94(10): 4884 - 4889. [Abstract] [Full Text] [PDF]