Bcl-2 blocks p53-dependent apoptosis

1994 ◽  
Vol 14 (4) ◽  
pp. 2556-2563
Author(s):  
S K Chiou ◽  
L Rao ◽  
E White
Keyword(s):  
P53 Protein ◽  
Growth Arrest ◽  
Suppressor Gene ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Permissive Temperature ◽  
Adenovirus E1a ◽  
Induction Of Apoptosis ◽  
Adenovirus E1b ◽  
State Growth

Adenovirus E1A expression recruits primary rodent cells into proliferation but fails to transform them because of the induction of programmed cell death (apoptosis). The adenovirus E1B 19,000-molecular-weight protein (19K protein), the E1B 55K protein, and the human Bcl-2 protein each cause high-frequency transformation when coexpressed with E1A by inhibiting apoptosis. Thus, transformation of primary rodent cells by E1A requires deregulation of cell growth to be coupled to suppression of apoptosis. The product of the p53 tumor suppressor gene induces apoptosis in transformed cells and is required for induction of apoptosis by E1A. The ability of Bcl-2 to suppress apoptosis induced by E1A suggested that Bcl-2 may function by inhibition of p53. Rodent cells transformed with E1A plus the p53(Val-135) temperature-sensitive mutant are transformed at the restrictive temperature and undergo rapid and complete apoptosis at the permissive temperature when p53 adopts the wild-type conformation. Human Bcl-2 expression completely prevented p53-mediated apoptosis at the permissive temperature and caused cells to remain in a predominantly growth-arrested state. Growth arrest was leaky, occurred at multiple points in the cell cycle, and was reversible. Bcl-2 did not affect the ability of p53 to localize to the nucleus, nor were the levels of the p53 protein altered. Thus, Bcl-2 diverts the activity of p53 from induction of apoptosis to induction of growth arrest, and it is thereby identified as a modifier of p53 function. The ability of Bcl-2 to bypass induction of apoptosis by p53 may contribute to its oncogenic and antiapoptotic activity.

scholarly journals Bcl-2 blocks p53-dependent apoptosis.

1994 ◽  
Vol 14 (4) ◽  
pp. 2556-2563 ◽  
Author(s):  
S K Chiou ◽  
L Rao ◽  
E White
Keyword(s):  
P53 Protein ◽  
Growth Arrest ◽  
Suppressor Gene ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Permissive Temperature ◽  
Adenovirus E1a ◽  
Induction Of Apoptosis ◽  
Adenovirus E1b ◽  
State Growth

Adenovirus E1A expression recruits primary rodent cells into proliferation but fails to transform them because of the induction of programmed cell death (apoptosis). The adenovirus E1B 19,000-molecular-weight protein (19K protein), the E1B 55K protein, and the human Bcl-2 protein each cause high-frequency transformation when coexpressed with E1A by inhibiting apoptosis. Thus, transformation of primary rodent cells by E1A requires deregulation of cell growth to be coupled to suppression of apoptosis. The product of the p53 tumor suppressor gene induces apoptosis in transformed cells and is required for induction of apoptosis by E1A. The ability of Bcl-2 to suppress apoptosis induced by E1A suggested that Bcl-2 may function by inhibition of p53. Rodent cells transformed with E1A plus the p53(Val-135) temperature-sensitive mutant are transformed at the restrictive temperature and undergo rapid and complete apoptosis at the permissive temperature when p53 adopts the wild-type conformation. Human Bcl-2 expression completely prevented p53-mediated apoptosis at the permissive temperature and caused cells to remain in a predominantly growth-arrested state. Growth arrest was leaky, occurred at multiple points in the cell cycle, and was reversible. Bcl-2 did not affect the ability of p53 to localize to the nucleus, nor were the levels of the p53 protein altered. Thus, Bcl-2 diverts the activity of p53 from induction of apoptosis to induction of growth arrest, and it is thereby identified as a modifier of p53 function. The ability of Bcl-2 to bypass induction of apoptosis by p53 may contribute to its oncogenic and antiapoptotic activity.

scholarly journals p53-mediated cell death: relationship to cell cycle control.

1993 ◽  
Vol 13 (3) ◽  
pp. 1415-1423 ◽  
Author(s):  
E Yonish-Rouach ◽  
D Grunwald ◽  
S Wilder ◽  
A Kimchi ◽  
E May ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Death ◽  
Interleukin 6 ◽  
Cell Cycle Progression ◽  
P53 Protein ◽  
Cell Cycle Control ◽  
Growth Arrest ◽  
Leukemic Cells ◽  
Temperature Sensitive ◽  
Permissive Temperature

M1 clone S6 myeloid leukemic cells do not express detectable p53 protein. When stably transfected with a temperature-sensitive mutant of p53, these cells undergo rapid cell death upon induction of wild-type (wt) p53 activity at the permissive temperature. This process has features of apoptosis. In a number of other cell systems, wt p53 activation has been shown to induce a growth arrest. Yet, wt 53 fails to induce a measurable growth arrest in M1 cells, and cell cycle progression proceeds while viability is being lost. There exists, however, a relationship between the cell cycle and p53-mediated death, and cells in G1 appear to be preferentially susceptible to the death-inducing activity of wt p53. In addition, p53-mediated M1 cell death can be inhibited by interleukin-6. The effect of the cytokine is specific to p53-mediated death, since apoptosis elicited by serum deprivation is refractory to interleukin-6. Our data imply that p53-mediated cell death is not dependent on the induction of a growth arrest but rather may result from mutually incompatible growth-regulatory signals.

scholarly journals Modulation of p53-mediated transcriptional repression and apoptosis by the adenovirus E1B 19K protein.

1995 ◽  
Vol 15 (2) ◽  
pp. 1060-1070 ◽  
Author(s):  
P Sabbatini ◽  
S K Chiou ◽  
L Rao ◽  
E White
Keyword(s):  
Transcriptional Activation ◽  
Transcriptional Repression ◽  
Growth Arrest ◽  
Temperature Sensitive ◽  
Wild Type ◽  
Dna Virus ◽  
Adenovirus E1a ◽  
Reporter Assays ◽  
Adenovirus E1b ◽  
Transforming Proteins

BRK cell lines that stably express adenovirus E1A and a murine temperature-sensitive p53 undergo apoptosis when p53 assumes the wild-type conformation. Expression of the E1B 19,000-molecular-weight (19K) protein rescues cells from this p53-mediated apoptosis and diverts cells to a growth-arrested state. As p53 likely functions as a tumor suppressor by regulating transcription, the ability of the E1B 19K protein to regulate p53-mediated transactivation and transcriptional repression was investigated. In promoter-reporter assays the E1B 19K did not block p53-mediated transactivation but did alleviate p53-mediated transcriptional repression. E1B 19K expression permitted efficient transcriptional activation of the p21/WAF-1/cip-1 mRNA by p53, consistent with maintenance of the growth arrest function of p53. The E1B 19K protein is thereby unique among DNA virus-transforming proteins that target p53 for inactivation in that it selectively modulates the transcriptional properties of p53. The E1B 19K protein also rescued cells from apoptosis induced by inhibitors of transcription and protein synthesis. This suggests that cell death may result from the inhibition of expression of survival factors which function to maintain cell viability. p53 may induce apoptosis through generalized transcriptional repression. In turn, the E1B 19K protein may prevent p53-mediated apoptosis by alleviating p53-mediated transcriptional repression.

p53-mediated cell death: relationship to cell cycle control

1993 ◽  
Vol 13 (3) ◽  
pp. 1415-1423
Author(s):  
E Yonish-Rouach ◽  
D Grunwald ◽  
S Wilder ◽  
A Kimchi ◽  
E May ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Death ◽  
Interleukin 6 ◽  
Cell Cycle Progression ◽  
P53 Protein ◽  
Cell Cycle Control ◽  
Growth Arrest ◽  
Leukemic Cells ◽  
Temperature Sensitive ◽  
Permissive Temperature

M1 clone S6 myeloid leukemic cells do not express detectable p53 protein. When stably transfected with a temperature-sensitive mutant of p53, these cells undergo rapid cell death upon induction of wild-type (wt) p53 activity at the permissive temperature. This process has features of apoptosis. In a number of other cell systems, wt p53 activation has been shown to induce a growth arrest. Yet, wt 53 fails to induce a measurable growth arrest in M1 cells, and cell cycle progression proceeds while viability is being lost. There exists, however, a relationship between the cell cycle and p53-mediated death, and cells in G1 appear to be preferentially susceptible to the death-inducing activity of wt p53. In addition, p53-mediated M1 cell death can be inhibited by interleukin-6. The effect of the cytokine is specific to p53-mediated death, since apoptosis elicited by serum deprivation is refractory to interleukin-6. Our data imply that p53-mediated cell death is not dependent on the induction of a growth arrest but rather may result from mutually incompatible growth-regulatory signals.

Identification of temperature-sensitive DNA- mutants of Chinese hamster cells affected in cellular and viral DNA synthesis

1986 ◽  
Vol 6 (12) ◽  
pp. 4594-4601
Author(s):  
J J Dermody ◽  
B E Wojcik ◽  
H Du ◽  
H L Ozer
Keyword(s):  
Dna Replication ◽  
Dna Synthesis ◽  
Chinese Hamster ◽  
Human Adenovirus ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Permissive Temperature ◽  
Dependent Manner ◽  
Viral Dna ◽  
Cell Functions

We described a strategy which facilitates the identification of cell mutants which are restricted in DNA synthesis in a temperature-dependent manner. A collection of over 200 cell mutants temperature-sensitive for growth was isolated in established Chinese hamster cell lines (CHO and V79) by a variety of selective and nonselective techniques. Approximately 10% of these mutants were identified as ts DNA- based on differential inhibition of macromolecular synthesis at the restrictive temperature (39 degrees C) as assessed by incorporation of [3H]thymidine and [35S]methionine. Nine such mutants, selected for further study, demonstrated rapid shutoff of DNA replication at 39 degrees C. Infections with two classes of DNA viruses extensively dependent on host-cell functions for their replication were used to distinguish defects in DNA synthesis itself from those predominantly affecting other aspects of DNA replication. All cell mutants supported human adenovirus type 2 (Ad2) and mouse polyomavirus DNA synthesis at the permissive temperature. Five of the nine mutants (JB3-B, JB3-O, JB7-K, JB8-D, and JB11-J) restricted polyomavirus DNA replication upon transfection with viral sequences at 33 degrees C and subsequent shift to 39 degrees C either before or after the onset of viral DNA synthesis. Only one of these mutants (JB3-B) also restricted Ad2 DNA synthesis after virion infection under comparable conditions. No mutant was both restrictive for Ad2 and permissive for polyomavirus DNA synthesis at 39 degrees C. The differential effect of these cell mutants on viral DNA synthesis is expected to assist subsequent definition of the biochemical defect responsible.

DBF8, an essential gene required for efficient chromosome segregation in Saccharomyces cerevisiae

1994 ◽  
Vol 14 (9) ◽  
pp. 6350-6360
Author(s):  
F Houman ◽  
C Holm
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Chromosome Segregation ◽  
Mutational Analysis ◽  
Essential Gene ◽  
Chromosome Loss ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Permissive Temperature ◽  
Nonsense Mutations ◽  
Carboxy Terminal

To investigate chromosome segregation in Saccharomyces cerevisiae, we examined a collection of temperature-sensitive mutants that arrest as large-budded cells at restrictive temperatures (L. H. Johnston and A. P. Thomas, Mol. Gen. Genet. 186:439-444, 1982). We characterized dbf8, a mutation that causes cells to arrest with a 2c DNA content and a short spindle. DBF8 maps to chromosome IX near the centromere, and it encodes a 36-kDa protein that is essential for viability at all temperatures. Mutational analysis reveals that three dbf8 alleles are nonsense mutations affecting the carboxy-terminal third of the encoded protein. Since all of these mutations confer temperature sensitivity, it appears that the carboxyl-terminal third of the protein is essential only at a restrictive temperature. In support of this conclusion, an insertion of URA3 at the same position also confers a temperature-sensitive phenotype. Although they show no evidence of DNA damage, dbf8 mutants exhibit increased rates of chromosome loss and nondisjunction even at a permissive temperature. Taken together, our data suggest that Dbf8p plays an essential role in chromosome segregation.

Growth-dependent regulation of system A in SV40-transformed fetal rat hepatocytes

1988 ◽  
Vol 255 (3) ◽  
pp. C261-C270 ◽  
Author(s):  
M. E. Handlogten ◽  
M. S. Kilberg
Keyword(s):  
Cell Density ◽  
De Novo ◽  
Membrane Vesicles ◽  
Rat Hepatocytes ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Permissive Temperature ◽  
Plasma Membrane Vesicles ◽  
Intact Cells ◽  
System A

Fetal RLA209-15 hepatocytes, transformed with a temperature-sensitive SV40 mutant, behave like fully differentiated cells at the growth-restrictive temperature of 40 degrees C. Conversely, incubation at the growth-permissive temperature of 33 degrees C results in a transformed phenotype characterized by rapid cell division and decreased production of liver-specific proteins. The results presented here demonstrate that the cells at 33 degrees C exhibited high rates of system A transport, but transfer to 40 degrees C reduced the activity greater than 50% within 24 h. This decline in transport was independent of cell density, although the basal rate of uptake was inversely proportional to cell density in rapidly dividing cells. Transfer of cells from 40 to 33 degrees C resulted in an enhancement of system A activity that was blocked by tunicamycin. Plasma membrane vesicles from cells maintained at either 33 or 40 degrees C retained uptake rates proportional to those in the intact cells; this difference in transport activity could also be demonstrated after detergent solubilization and reconstitution. Collectively, these data indicate that de novo synthesis of the system A carrier is regulated in conjunction with temperature-dependent cell growth in RLA209-15 hepatocytes.

Correction of the defect in initiation of DNA replication in a temperature-sensitive mutant hamster cell line by in vitro addition of extracts from normal cells

1985 ◽  
Vol 5 (4) ◽  
pp. 902-905
Author(s):  
M Narkhammar ◽  
R Hand
Keyword(s):  
Cell Line ◽  
Nuclear Extract ◽  
Cell Extract ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Permissive Temperature ◽  
Wild Type ◽  
Whole Cell ◽  
Mutant Cells

ts BN-2 is a temperature-sensitive hamster cell line that is defective in DNA synthesis at the restrictive temperature. The mutant expresses its defect during in vitro replication in whole-cell lysates. Addition of a high-salt-concentration extract from wild-type BHK-21, revertant RBN-2, or CHO cells to mutant cells lysed with 0.01% Brij 58 increased the activity in the mutant three- to fourfold, so that it reached 85% of the control value, and restored replicative synthesis. The presence of extract had an insignificant effect on wild-type and revertant replication and on mutant replication at the permissive temperature. Extract prepared from mutant cells was less effective than the wild-type cell extract was. Also, the stimulatory activity was more heat labile in the mutant than in the wild-type extract. Nuclear extract was as active as whole-cell extract.

scholarly journals Deficiencies in vesicular transport mediated by TRAPPC4 are associated with severe syndromic intellectual disability

Brain ◽  
2019 ◽  
Vol 143 (1) ◽  
pp. 112-130 ◽  
Author(s):  
Nicole J Van Bergen ◽  
Yiran Guo ◽  
Noraldin Al-Deri ◽  
Zhanna Lipatova ◽  
Daniela Stanga ◽  
...  
Keyword(s):  
Neurological Disorders ◽  
Single Nucleotide Polymorphism Array ◽  
Polyacrylamide Gel Electrophoresis ◽  
Cerebellar Atrophy ◽  
Sensorineural Deafness ◽  
Size Exclusion ◽  
Autophagic Flux ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Permissive Temperature

Abstract The conserved transport protein particle (TRAPP) complexes regulate key trafficking events and are required for autophagy. TRAPPC4, like its yeast Trs23 orthologue, is a core component of the TRAPP complexes and one of the essential subunits for guanine nucleotide exchange factor activity for Rab1 GTPase. Pathogenic variants in specific TRAPP subunits are associated with neurological disorders. We undertook exome sequencing in three unrelated families of Caucasian, Turkish and French-Canadian ethnicities with seven affected children that showed features of early-onset seizures, developmental delay, microcephaly, sensorineural deafness, spastic quadriparesis and progressive cortical and cerebellar atrophy in an effort to determine the genetic aetiology underlying neurodevelopmental disorders. All seven affected subjects shared the same identical rare, homozygous, potentially pathogenic variant in a non-canonical, well-conserved splice site within TRAPPC4 (hg19:chr11:g.118890966A>G; TRAPPC4: NM_016146.5; c.454+3A>G). Single nucleotide polymorphism array analysis revealed there was no haplotype shared between the tested Turkish and Caucasian families suggestive of a variant hotspot region rather than a founder effect. In silico analysis predicted the variant to cause aberrant splicing. Consistent with this, experimental evidence showed both a reduction in full-length transcript levels and an increase in levels of a shorter transcript missing exon 3, suggestive of an incompletely penetrant splice defect. TRAPPC4 protein levels were significantly reduced whilst levels of other TRAPP complex subunits remained unaffected. Native polyacrylamide gel electrophoresis and size exclusion chromatography demonstrated a defect in TRAPP complex assembly and/or stability. Intracellular trafficking through the Golgi using the marker protein VSVG-GFP-ts045 demonstrated significantly delayed entry into and exit from the Golgi in fibroblasts derived from one of the affected subjects. Lentiviral expression of wild-type TRAPPC4 in these fibroblasts restored trafficking, suggesting that the trafficking defect was due to reduced TRAPPC4 levels. Consistent with the recent association of the TRAPP complex with autophagy, we found that the fibroblasts had a basal autophagy defect and a delay in autophagic flux, possibly due to unsealed autophagosomes. These results were validated using a yeast trs23 temperature sensitive variant that exhibits constitutive and stress-induced autophagic defects at permissive temperature and a secretory defect at restrictive temperature. In summary we provide strong evidence for pathogenicity of this variant in a member of the core TRAPP subunit, TRAPPC4 that associates with vesicular trafficking and autophagy defects. This is the first report of a TRAPPC4 variant, and our findings add to the growing number of TRAPP-associated neurological disorders.

scholarly journals BCR-ABL maintains resistance of chronic myelogenous leukemia cells to apoptotic cell death [published erratum appears in Blood 1994 Jun 15;83(12):3835]

Blood ◽  
1994 ◽  
Vol 83 (5) ◽  
pp. 1179-1187 ◽  
Author(s):  
A McGahon ◽  
R Bissonnette ◽  
M Schmitt ◽  
KM Cotter ◽  
DR Green ◽  
...  
Keyword(s):  
Cell Death ◽  
Chronic Myelogenous Leukemia ◽  
Apoptotic Cell ◽  
Chimeric Protein ◽  
Chemotherapeutic Agents ◽  
Myelogenous Leukemia ◽  
Temperature Sensitive ◽  
Permissive Temperature ◽  
Expression Of Genes ◽  
Induction Of Apoptosis

Abstract Apoptosis is the major form of cell death associated with the action of chemotherapeutic agents on tumor cells, and therefore the expression of genes that interfere with apoptosis can have important consequences for the efficacy of therapeutic approaches. Here we show that K562, a chronic myelogenous leukemia (CML) cell line expressing the BCR-ABL fusion protein, are resistant to the induction of apoptosis by a number of agents and conditions. Antisense oligodeoxynucleotides corresponding to the translation start of bcr downregulate bcr-abl protein in these cells and render them susceptible to induction of apoptosis by chemotherapeutic agents or serum deprivation. Expression of a temperature sensitive v-Abl protein reverses the effects of the antisense oligonucleotides, such that the cells remain resistant to apoptosis at the permissive temperature. These data indicate that bcr- abl acts as an anti-apoptosis gene in CML cells and suggests that the effect is dependent on the abl kinase activity in this chimeric protein. Inhibition of bcr-abl to render CML cells susceptible to apoptosis can be combined with therapeutic drugs and/or treatment capable of inducing apoptosis to provide an effective strategy for elimination of these cells.

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