Browsing by Subject "Protein bax"

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Open Access
The involvement of apoptotic regulators during in vitro decidualization
(Society of the European Journal of Endocrinology, 2003) Akcali, K. C.; Gibori, G.; Khan, S. A.
Objectives: The uterus responds to an implanting blastocyst by undergoing extensive tissue modification leading to decidualization. This modification includes differentiation and apoptosis of epithelial as well as stromal cell compartments. It is generally accepted that the decidual cell regression pattern is similar to the pattern of initial differentiation, suggesting that decidual cell death is the end point of timed differentiation. However, the molecular mechanisms controlling these events are not understood clearly. Therefore, we aimed to investigate the involvement of apoptotic factors using an in vitro cell culture system. Design: In order to assess the role of apoptotic factors during decidualization, we used a decidual cell line (GG-AD) that had been transformed with a temperature-sensitive SV-40 mutant. At the non-permissive temperature (39°C), these cells showed the characteristics of differentiated decidual cells. They dedifferentiated into stromal cells when the temperature was shifted back to 33°C. Methods: We performed Northern blot analysis for bax, bcl-XL and bcl-2 at both temperatures. The onset of apoptosis was examined by Annexin V staining. The expression of p53 protein was also determined by Western blot. Results: We found an increase in the expression of bax when GG-AD cells were grown at 39°C. We also showed apoptosis with Annexin V staining at 39°C. The p53 protein expression was also similar to that of the animal models, suggesting that the programmed cell death of the decidual cells occurred in a p53-independent manner. Conclusions: These data indicate that a parallelism exists between the increased expression of pro-apoptotic genes and decidual cell death, similar to animal models. Therefore, an in vitro model of GG-AD cells can be used to assess directly the relationship between apoptotic regulators and decidualization and could be used to study the mechanism of decidual cell regression.
Open Access
p53 mutation with frequent novel codons but not a mutator phenotype in BRCA1-and BRCA2-associated breast tumours
(Nature Publishing Group, 1998) Crook, T.; Brooks, L. A.; Crossland, S.; Osin, P.; Barker, K. T.; Waller, J.; Philp, E.; Smith, P. D.; Yulug, I.; Peto, J.; Parker, G.; Allday, M. J.; Crompton, M. R.; Gusterson, B. A.
The status of p53 was investigated in breast tumours arising in germ-line carriers of mutant alleles of BRCA1 and BRCA2 and in a control series of sporadic breast tumours. p53 expression was detected in 20/26 (77%) BRCA1-, 10/22 (45%) BRCA2-associated and 25/72 (35%) grade-matched sporadic tumours. Analysis of p53 sequence revealed that the gene was mutant in 33/50 (66%) BRCA-associated tumours, whereas 7/20 (35%) sporadic grade-matched tumours contained p53 mutation (P < 0.05). A number of the mutations detected in the BRCA-associated tumours have not been previously described in human cancer databases, whilst others occur extremely rarely. Analysis of additional genes, p16(INK4), Ki-ras and β-globin revealed absence or very low incidence of mutations, suggesting that the higher frequency of p53 mutation in the BRCA-associated tumours does not reflect a generalized increase in susceptibility to the acquisition of somatic mutation. Furthermore, absence of frameshift mutations in the polypurine tracts present in the coding sequence of the TGF β type II receptor (TGF β IIR) and Bax implies that loss of function of BRCA1 or BRCA2 does not confer a mutator phenotype such as that found in tumours with microsatellite instability (MSI). p21(Waf1) was expressed in BRCA-associated tumours regardless of p53 status and, furthermore, some tumours expressing wild-type p53 did not express detectable p21(Waf1). These data do not support, therefore, the simple model based on studies of BRCA-/- embryos, in which mutation of p53 in BRCA-associated tumours results in loss of p21(Waf1) expression and deregulated proliferation. Rather, they imply that proliferation of such tumours will be subject to multiple mechanisms of growth regulation.