scholarly journals Concerted Regulation of Wild-Type p53 Nuclear Accumulation and Activation by S100B and Calcium-Dependent Protein Kinase C

1999 ◽  
Vol 19 (10) ◽  
pp. 7168-7180 ◽  
Author(s):  
Christian Scotto ◽  
Christian Delphin ◽  
Jean Christophe Deloulme ◽  
Jacques Baudier
Keyword(s):  
Nuclear Translocation ◽  
Growth Arrest ◽  
Nuclear Accumulation ◽  
Temperature Sensitive ◽  
Checkpoint Control ◽  
Wild Type ◽  
Calcium Dependent ◽  
Mouse Embryo Fibroblasts ◽  
Wild Type P53 ◽  
Embryo Fibroblasts

ABSTRACT The calcium ionophore ionomycin cooperates with the S100B protein to rescue a p53-dependent G1 checkpoint control in S100B-expressing mouse embryo fibroblasts and rat embryo fibroblasts (REF cells) which express the temperature-sensitive p53Val135 mutant (C. Scotto, J. C. Deloulme, D. Rousseau, E. Chambaz, and J. Baudier, Mol. Cell. Biol. 18:4272–4281, 1998). We investigated in this study the contributions of S100B and calcium-dependent PKC (cPKC) signalling pathways to the activation of wild-type p53. We first confirmed that S100B expression in mouse embryo fibroblasts enhanced specific nuclear accumulation of wild-type p53. We next demonstrated that wild-type p53 nuclear translocation and accumulation is dependent on cPKC activity. Mutation of the five putative cPKC phosphorylation sites on murine p53 into alanine or aspartic residues had no significant effect on p53 nuclear localization, suggesting that the cPKC effect on p53 nuclear translocation is indirect. A concerted regulation by S100B and cPKC of wild-type p53 nuclear translocation and activation was confirmed with REF cells expressing S100B (S100B-REF cells) overexpressing the temperature-sensitive p53Val135 mutant. Stimulation of S100B-REF cells with the PKC activator phorbol ester phorbol myristate acetate (PMA) promoted specific nuclear translocation of the wild-type p53Val135 species in cells positioned in early G1 phase of the cell cycle. PMA also substituted for ionomycin in the mediating of p53-dependent G1 arrest at the nonpermissive temperature (37.5°C). PMA-dependent growth arrest was linked to the cell apoptosis response to UV irradiation. In contrast, growth arrest mediated by a temperature shift to 32°C protected S100B-REF cells from apoptosis. Our results suggest a model in which calcium signalling, linked with cPKC activation, cooperates with S100B to promote wild-type p53 nuclear translocation in early G1 phase and activation of a p53-dependent G1checkpoint control.

scholarly journals Restoration of endogenous wild-type p53 activity in a glioblastoma cell line with intrinsic temperature-sensitive p53 induces growth arrest but not apoptosis

2001 ◽  
Vol 94 (1) ◽  
pp. 35-43 ◽  
Author(s):  
Jun Ikeda ◽  
Mitsuhiro Tada ◽  
Nobuaki Ishii ◽  
Hideyuki Saya ◽  
Kazuhiko Tsuchiya ◽  
...  
Keyword(s):  
Cell Line ◽  
Growth Arrest ◽  
Temperature Sensitive ◽  
Glioblastoma Cell Line ◽  
Glioblastoma Cell ◽  
Wild Type ◽  
Wild Type P53

scholarly journals Inhibition of p53-mediated growth arrest by overexpression of cyclin-dependent kinases.

1996 ◽  
Vol 16 (8) ◽  
pp. 4445-4455 ◽  
Author(s):  
K M Latham ◽  
S W Eastman ◽  
A Wong ◽  
P W Hinds
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Progression ◽  
Growth Arrest ◽  
Temperature Sensitive ◽  
Wild Type ◽  
Aberrant Expression ◽  
Cycle Progression ◽  
Cyclin Dependent Kinases ◽  
Rat Fibroblasts ◽  
Wild Type P53

Rat fibroblasts transformed by a temperature-sensitive mutant of murine p53 undergo a reversible growth arrest in G1 at 32.5 degrees C, the temperature at which p53 adopts a wild-type conformation. The arrested cells contain inactive cyclin-dependent kinase 2 (cdk2) despite the presence of high levels of cyclin E and cdk-activating kinase activity. This is due in part to p53-dependent expression of the p2l cdk inhibitor. Upon shift to 39 degrees C, wild-type p53 is lost and cdk2 activation and pRb phosphorylation occur concomitantly with loss of p2l. This p53-mediated growth arrest can be abrogated by overexpression of cdk4 and cdk6 but not cdk2 or cyclins, leading to continuous proliferation of transfected cells in the presence of wild-type p53 and p2l. Kinase-inactive counterparts of cdk4 and cdk6 also rescue these cells from growth arrest, implicating a noncatalytic role for cdk4 and cdk6 in this resistance to p53-mediated growth arrest. Aberrant expression of these cell cycle kinases may thus result in an oncogenic interference with inhibitors of cell cycle progression.

scholarly journals Calcium and S100B Regulation of p53-Dependent Cell Growth Arrest and Apoptosis

1998 ◽  
Vol 18 (7) ◽  
pp. 4272-4281 ◽  
Author(s):  
Christian Scotto ◽  
Jean Christophe Deloulme ◽  
Denis Rousseau ◽  
Edmond Chambaz ◽  
Jacques Baudier
Keyword(s):  
Cell Growth ◽  
Uv Irradiation ◽  
Growth Arrest ◽  
Nuclear Accumulation ◽  
Permissive Temperature ◽  
Wild Type ◽  
Cell Growth Arrest ◽  
Calcium Dependent ◽  
Inhibition Of Growth ◽  
Dependent Cell

ABSTRACT In glial C6 cells constitutively expressing wild-type p53, synthesis of the calcium-binding protein S100B is associated with cell density-dependent inhibition of growth and apoptosis in response to UV irradiation. A functional interaction between S100B and p53 was first demonstrated in p53-negative mouse embryo fibroblasts (MEF cells) by sequential transfection with the S100B and the temperature-sensitive p53Val135 genes. We show that in MEF cells expressing a low level of p53Val135, S100B cooperates with p53Val135 in triggering calcium-dependent cell growth arrest and cell death in response to UV irradiation at the nonpermissive temperature (37.5°C). Calcium-dependent growth arrest of MEF cells expressing S100B correlates with specific nuclear accumulation of the wild-type p53Val135 conformational species. S100B modulation of wild-type p53Val135 nuclear translocation and functions was confirmed with the rat embryo fibroblast (REF) cell line clone 6, which is transformed by oncogenic Ha-ras and overexpression of p53Val135. Ectopic expression of S100B in clone 6 cells restores contact inhibition of growth at 37.5°C, which also correlates with nuclear accumulation of the wild-type p53Val135 conformational species. Moreover, a calcium ionophore mediates a reversible G1 arrest in S100B-expressing REF (S100B-REF) cells at 37.5°C that is phenotypically indistinguishable from p53-mediated G1arrest at the permissive temperature (32°C). S100B-REF cells proceeding from G1 underwent apoptosis in response to UV irradiation. Our data support a model in which calcium signaling and S100B cooperate with the p53 pathways of cell growth inhibition and apoptosis.

scholarly journals Differential ability of a T-antigen transport-defective mutant of simian virus 40 to transform primary and established rodent cells.

1985 ◽  
Vol 5 (5) ◽  
pp. 1043-1050 ◽  
Author(s):  
R E Lanford ◽  
C Wong ◽  
J S Butel
Keyword(s):  
Cell Lines ◽  
Mouse Embryo ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
T Antigen ◽  
Wild Type ◽  
Mouse Embryo Fibroblasts ◽  
Established Cell Lines ◽  
Established Cell ◽  
Embryo Fibroblasts

The transforming potential and oncogenicity of a simian virus 40 (SV40) mutant affecting T-antigen (T-ag), SV40(cT)-3, was examined in an effort to dissect T-ag functions in transformation. SV40(cT)-3 has a point mutation at nucleotide 4434 that abolishes the transport of T-ag to the nucleus but does not affect its association with the cell surface. Transfection-transformation assays were performed with primary cells and established cell lines of mouse and rat origin. The efficiency of transformation for established cell lines by SV40(cT)-3 was comparable to that of wild-type SV40, indicating that transformation of established cell lines can occur in the absence of detectable amounts of nuclear T-ag. Transformation of primary mouse embryo fibroblasts by SV40(cT)-3 was markedly influenced by culture conditions; the relative transforming frequency was dramatically reduced in assays involving focus formation in low serum concentrations or anchorage-independent growth. Immunofluorescence tests revealed that the transformed mouse embryo fibroblasts partially transport the mutant cT-ag to the cell nucleus. Transformed cell lines induced by SV40(cT)-3 did not differ in growth properties from wild-type transformants. SV40(cT)-3 was completely defective for the transformation of primary baby rat kidney cells, a primary cell type unable to transport the mutant T-ag to the nucleus. The intracellular localization of cellular protein p53 was found to mimic T-ag distribution in all the transformants analyzed. The mutant virus was weakly oncogenic in vivo: the induction of tumors in newborn hamsters by SV40(cT)-3 was reduced in incidence and delayed in appearance in comparison to wild-type SV40. These observations suggest that cellular transformation is regulated by both nuclear and surface-associated forms of SV40 T-ag.

An accelerated senescence response to radiation in wild-type p53 glioblastoma multiforme cells

2006 ◽  
Vol 105 (1) ◽  
pp. 111-118 ◽  
Author(s):  
Quincy A. Quick ◽  
David A. Gewirtz
Keyword(s):  
Glioblastoma Multiforme ◽  
Growth Arrest ◽  
Terminal Deoxynucleotidyl Transferase ◽  
Viable Cell Number ◽  
Mutant P53 ◽  
Wild Type ◽  
Fractionated Radiotherapy ◽  
Accelerated Senescence ◽  
Wild Type P53 ◽  
U87 Cells

Object Radiotherapy is one of the few treatment options available for glioblastoma multiforme (GBM); however, the basis for its overall ineffectiveness in GBM is not fully understood. The present study was designed to explore the nature of the response to ionizing radiation in GBM cells to gain insight into the basis for the general failure of radiotherapy in the treatment of this disease. Methods The response to fractionated radiotherapy was examined in GBM cell lines with differing p53 status. A viable cell number was determined during an 8-day period; accelerated senescence was based on β-galactosidase staining and cell morphology; apoptosis was evaluated by the terminal deoxynucleotidyl transferase–mediated deoxyuridine triphosphate nick-end labeling assay and fluorescence-activated cell-sorter analysis, whereas the expression of cell-cycle regulatory proteins was monitored by Western blot analysis. Based on clonogenic survival, the wild-type p53 U87 cells and mutant p53 T98 cells demonstrated essentially identical sensitivity to fractionated radiotherapy; however, neither cell line underwent apoptosis, and the primary response to irradiation was growth arrest. The wild-type p53 GBM cells showed clear evidence of accelerated senescence in response to irradiation. In contrast, senescence was not evident in mutant p53 GBM cells or GBM cells in which p53 function was abrogated by the viral E6 protein. The T98 (mutant p53) cells demonstrated a relatively robust proliferative recovery whereas both the rate and extent of recovery were attenuated in the wild-type p53 U87 cells. Conclusions Both accelerated senescence and conventional growth arrest are likely to represent alternative responses to apoptosis in irradiated GBM cells.

scholarly journals Regulation of cell proliferation by ERK and signal-dependent nuclear translocation of ERK is dependent on Tm5NM1-containing actin filaments

2015 ◽  
Vol 26 (13) ◽  
pp. 2475-2490 ◽  
Author(s):  
Galina Schevzov ◽  
Anthony J. Kee ◽  
Bin Wang ◽  
Vanessa B. Sequeira ◽  
Jeff Hook ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Actin Filaments ◽  
Nuclear Translocation ◽  
Genetic Manipulation ◽  
Wild Type ◽  
Proximity Ligation ◽  
Mouse Embryo Fibroblasts ◽  
Wild Type Mefs

ERK-regulated cell proliferation requires multiple phosphorylation events catalyzed first by MEK and then by casein kinase 2 (CK2), followed by interaction with importin7 and subsequent nuclear translocation of pERK. We report that genetic manipulation of a core component of the actin filaments of cancer cells, the tropomyosin Tm5NM1, regulates the proliferation of normal cells both in vitro and in vivo. Mouse embryo fibroblasts (MEFs) lacking Tm5NM1, which have reduced proliferative capacity, are insensitive to inhibition of ERK by peptide and small-molecule inhibitors, indicating that ERK is unable to regulate proliferation of these knockout (KO) cells. Treatment of wild-type MEFs with a CK2 inhibitor to block phosphorylation of the nuclear translocation signal in pERK resulted in greatly decreased cell proliferation and a significant reduction in the nuclear translocation of pERK. In contrast, Tm5NM1 KO MEFs, which show reduced nuclear translocation of pERK, were unaffected by inhibition of CK2. This suggested that it is nuclear translocation of CK2-phosphorylated pERK that regulates cell proliferation and this capacity is absent in Tm5NM1 KO cells. Proximity ligation assays confirmed a growth factor–stimulated interaction of pERK with Tm5NM1 and that the interaction of pERK with importin7 is greatly reduced in the Tm5NM1 KO cells.

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