Abstract
We recently identified a novel myristylated protein kinase C (PKC) substrate, named SSeCKS (pronounced essex), whose transcription is suppressed >15 fold in src- or ras-transformed rodent fibroblasts, but not in raf-transformed cells [1, 2]. SSeCKS associates with and controls the elaboration of a cortical cytoskeletal matrix in response to phorbol esters [2], and overexpression of SSeCKS causes growth arrest of untransformed NIH3T3 cells [3]. Our preliminary data suggested that SSeCKS functions as a negative mitogenic regulator by controlling cytoskeletal architecture and that serine phosphorylation of SSeCKS by kinases such as PKC alters its interaction with cytoskeletal matrices and its ability to control mitogenesis. Here, we determine the effects of culture confluency, growth arrest and serum response on the steady-state abundance of SSeCKS RNA and protein and on the relative level of phosphoserine-free SSeCKS. SSeCKS transcription is initially induced by serum factors and by cont act-inhibited growth rather than by cell-cycle arrest induced by serum starvation, hydroxyurea or nocodazole, and following serum-induced G1/S progression, SSeCKS transcription is suppressed. SSeCKS protein is hyperphosphorylated on serine residues during G1/S progression but not during the G2/M phase. Finally, we show that the induction of SSeCKS protein expression by contact inhibition is independent of SSeCKS' serum responsiveness. These data suggest that SSeCKS expression and function can be controlled at either the transcriptional or post-translational level in response to serum factors and culture confluency. The data strengthen the notion that SSeCKS plays an important, yet transient, role in cell cycle progression from G0 to G1 that differs from its role in controlling contact-inhibited growth. (Mol Cell Biochem 175: 233–241, 1997)
Similar content being viewed by others
References
Lin X, Nelson PJ, Frankfort B, Tombler E, Johnson R, Gelman IH: Isolation and characterization of a novel mitogenic regulatory gene, 322, which is transcriptionally suppressed in cells transformed by src and ras. Mol Cell Biol 15: 2754–2762, 1995
Lin X, Tombler E, Nelson PJ, Ross M, Gelman IH: A novel src-and ras-suppressed protein kinase C substrate associated with cytoskeletal architecture. J Biol Chem 271: 28430–28438, 1996
Lin X, Gelman IH: Re-expression of the major protein kinase C substrate, SSeCKS, suppresses v-src-induced morphological transformation and tumorigenesis. Cancer Res 57: 2304–2312, 1997
Jaken S: Protein kinase C isozymes and substrates. Curr Opin Cell Biol 8: 168–173, 1996
Liu JP: Protein kinase C and its substrates. Mol Cell Endocrinol 116: 1–29, 1996
Elder PK, Schmidt W, Ono T, Getz MJ: Specific stimulation of actin gene transcription by epidermal growth factor and cycloheximide. Proc Natl Acad Sci USA 81: 7476–7480, 1984
Gluck U, Rodriguez-Fernandez JL, Pankov R, Ben Ze'ev A: Regulation of adherens junction protein expression in growth-activated 3T3 cells and in regenerating liver. Exp Cell Res 202: 477–486, 1992
Ben Ze'ev A: Animal cell shape changes and gene expression. Bioessays 13: 207–212, 1991
Ben Ze'ev A, Reiss R, Bendori R, Gorodecki B: Transient induction of vinculin gene expression in 3T3 fibroblasts stimulated by serumgrowth factors. Cell Reg 1: 621–636, 1990
Symons M: The Rac and Rho pathways as a source of drug targets for ras-mediated malignancies. Curr Opin Biotech 6: 668–674, 1995
Varner JA, Emerson DA, Juliano RL: Integrin β5β1 expression negatively regulates cell growth: Reversal by attachment to fibronectin. Mol Biol Cell 6: 725–740, 1995
Gluck U, Ben Ze'ev A: Modulation of alpha-actinin levels affects cell motility and confers tumorigenicity on 3T3 cells. J Cell Sci 107: 1773–1782, 1994
Boyd J, Risinger JI, Wiseman RW, Merrick BA, Selkirk JK, Barrett JC: Regulation of microfilament organization and anchorageindependent growth by tropomyosin 1. Proc Natl Acad Sci U S A 92: 11534–11538, 1995
Tanaka M, Mullauer L, Ogiso Y, Fujita H, Moriya S, Furuuchi K et al.: Gelsolin: A candidate for suppressor of human bladder cancer. Cancer Res 55: 3228–3232, 1995
Symington BE: Fibronectin receptor overexpression and loss of transformed phenotype in a stable variant of the K562 cell line. Cell Reg 1: 637–648, 1990
Damsky CH, Werb Z: Signal transduction by integrin receptors for extracellular matrix: cooperative processing of extracellular information. Curr Opin Cell Biol 4: 772–781, 1992
Gumbiner BM: Cell Adhesion: The molecular basis of tissue architecture and morphogenesis. Cell 84: 345–357, 1996
Lauffenburger DA: Cell migration: A physically integrated molecular process. Cell 84: 359–369, 1996
Aoyama A, Klementz R: Oncogene-mediated effects on cellular gene expression. Crit Rev Oncogenesis 4: 53–94, 1993
Bradford M: A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Anal Biochem 72: 248–254, 1976
Kiley SC, Jaken S, Whelan R, Parker PJ: Intracellular targeting of protein kinase C isoenzymes: Functional implications. Biochem Soc Trans 23: 601–605, 1995
Gelman IH, Wang A: Down-regulated expression of the major PKC substrate, SSeCKS, in breast cancer cell lines: Potential role as a tumor suppressor. Manuscript in preparation 1996
Rosales C, O'Brien V, Kornberg L, Juliano R: Signal transduction by cell adhesion receptors. Biochim Biophys Acta 1242: 77–98, 1995
Guadagno TM, Assoian RK: G1/S control of anchorage-independent growth in the fibroblast cell cycle. J Cell Biol 115: 1419–1425, 1991
Usui T, Yoshida M, Abe K, Osada H, Isono K, Beppu T: Uncoupled cell cycle without mitosis induced by a protein kinase inhibitor, K-252a. J Cell Biol 115: 1275–1282, 1991
Minana MD, Felipo V, Grisolia S: Differential effects of the protein kinase C inhibitors H7 and calphostin C on the cell cycle of neuroblastoma cells. Brain Res 596: 157–162, 1992
Watanabe T, Ono Y, Taniyama Y, Hazama K, Igarashi K, Ogita K et al.: Cell division arrest induced by phorbol ester in CHO cells overexpressing protein kinase C-delta subspecies. Proc Natl Acad Sci U S A 89: 10159–10163, 1992
Gustincich S, Schneider C: Serum deprivation response gene is induced by serum starvation but not by contact inhibition. Cell Growth Differ 4: 753–760, 1993
Herget T, Brooks SF, Broad S, Rozengurt E: Expression of the major protein kinase C substrate, the acidic 80 kD myristoylated alanine-rich C kinase substrate, increases sharply when Swiss 3T3 cells move out of cycle and enter G0. Proc Natl Acad Sci 90: 2945–2949, 1993
Moreton K, Turner R, Blake N, Paton A, Groome N, Rumsby M: Protein expression of the alpha, gamma, delta and epsilon subspecies of protein kinase C changes as C6 glioma cells become contact inhibited and quiescent in the presence of serum. FEBS Lett 372: 33–38, 1995
Brancolini C, Schneider C: Phosphorylation of the growth arrestspecific protein Gas2 is coupled to actin rearrangements during G0?G1 transition in NIH 3T3 cells. J Cell Biol 124: 743–756, 1994
Gradl G, Faust D, Oesch F, Wieser RJ: Density-dependent regulation of cell growth by contactinhibin and the contactinhibin receptor. Curr Biol 5: 526–535, 1995
Gebbink MF, Zondag GC, Koningstein GM, Feiken E, Wubbolts RW, Moolenaar WH: Cell surface expression of receptor protein tyrosine phosphatase RPTP mu is regulated by cell-cell contact. J Cell Biol 131: 251–260, 1995
den Hertog J, Sap J, Pals CE, Schlessinger J, Kruijer W: Stimulation of receptor protein-tyrosine phosphatase alpha activity and phosphorylation by phorbol ester. Cell Growth Diff 6: 303–307, 1995
Pomies P, Frachet P, Block MR: Control of the β5β1 integrin/ fibronectin interaction in vitro by the serine/threonine protein phosphatase calcineurin. Biochem 34: 5104–5112, 1995
Hendey B, Klee CB, Maxfield FR: Inhibition of neutrophil chemokinesis on vitronectin by inhibitors of calcineurin. Science 258: 296–299, 1992
Soma MR, Baetta R, Bergamaschi S, De Renzis MR, Davegna C, Battaini R, Govoni S: PKC activity in rat C6 glioma cells: Changes associated with cell cycle and simvastatin treatment. BBRC 200: 1143–1149, 1994
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Nelson, P.J., Gelman, I.H. Cell-cycle regulated expression and serine phosphorylation of the myristylated protein kinase C substrate, SSeCKS: Correlation with culture confluency, cell cycle phase and serum response. Mol Cell Biochem 175, 233–241 (1997). https://doi.org/10.1023/A:1006836003758
Issue Date:
DOI: https://doi.org/10.1023/A:1006836003758