Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P10415 (Bcl-2)
 33,771 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The inhibin-alpha gene is expressed in a tissue-specific manner, and its protein product dimerizes with one of two beta-subunits to form bioactive heterodimers. To characterize the cis-acting elements involved in directing gonad- and adrenal-specific expression of inhibin-alpha, transgenic mice were generated that carried 2.5 or 6 kilobases (kb) of the 5'-flanking region of the mouse inhibin-alpha gene driving the human bcl-2 complementary DNA. Using an antibody specific for human Bcl-2, Western blotting and immunocytochemical analyses showed that both enhancer/promoter fragments direct transgene expression to the ovary, testis, and adrenal gland. The 6-kb fragment targeted the ovarian transgene expression in interstitial cells and young corpora lutea as well as granulosa and thecal cells of secondary, antral, and preovulatory follicles. In ovaries of animals with the 2.5-kb fragment, transgene expression was also detected in interstitial cells and young corpora lutea, but only in granulosa and thecal cells from antral and preovulatory follicles. The ovarian transgene expression in animals carrying the 6-kb inhibin-alpha promoter/bcl-2 construct was stimulated by gonadotropin treatment, with greater than 10-fold increases observed 2 days after PMSG stimulation. In the testes of both types of transgenic animals, immunoreactive Bcl-2 was predominantly detected in Sertoli cells of seminiferous tubules. Sporadic expression was also observed in some interstitial cells. In the adrenal gland, reporter protein was detected in the zona fasciculata of both types of transgenic animals during adult life; however, transgene expression was detected in zona fasciculata of young (21-day-old) animals with the 6-kb, but not the 2.5-kb, promoter construct. Thus, the 2.5-kb inhibin-alpha 5'-proximal DNA sequence directs transgene expression in mature ovarian follicles and testicular Sertoli cells. In contrast, enhancer elements in the 6-kb fragment are required for expression in preantral follicles and in the adrenal of immature animals. The inhibin-alpha promoter/enhancer used here represents unique DNA sequences for ovarian-specific transgene expression and is useful for future analysis of gonadal and adrenal cell functions.
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PMID:Different 5'-flanking regions of the inhibin-alpha gene target transgenes to the gonad and adrenal in an age-dependent manner in transgenic mice. 758 11

Hygromycin B, an aminoglycoside antibiotic that is widely used to establish stable mammalian cell lines that carry a bacterial gene conferring resistance to the drug, is shown here to induce apoptotic programmed cell death in susceptible cells. Dying cells exhibited typical features of apoptosis, including cell shrinkage, membrane blebbing, nuclear pyknosis, and extensive internucleosomal fragmentation of DNA. Employing concentrations of hygromycin B that are typically used for selecting stable cell lines, we show that susceptible cells die rapidly, exhibiting the morphological properties of apoptosis by 18 h and detectable DNA fragmentation as early as 2 h after receiving the drug. G418, on the other hand, required days to cause cell death, which was not accompanied by internucleosomal DNA fragmentation. Apoptotic cell killing by hygromycin B did not require expression of wild-type p53 and was suppressed by both Bcl-2 and the Adenovirus type 5 E1B 19-kDa protein.
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PMID:Induction of p53-independent apoptosis by hygromycin B: suppression by Bcl-2 and adenovirus E1B 19-kDa protein. 758 55

Apoptosis is an active mechanism of cell death which can be initiated in response to various stimuli including virus infections. In this work, we demonstrate that lytic infection by varicella-zoster virus (VZV), a human herpesvirus, is characterized by nuclear fragmentation of DNA into oligonucleosomal fragments and by chromatin condensation. In vitro, VZV-induced cell death is actually mediated by apoptosis. The mechanisms developed by cells to protect themselves against apoptosis could be one of the parameters allowing the establishment of virus latency. In the case of VZV, which can remain latent in sensory ganglia, we have not yet identified a cellular or viral protein which could play this protective role, since the observed apoptosis mechanism seems to be independent from Bcl-2, the most frequently described inhibitor of apoptosis.
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PMID:Varicella-zoster virus induces apoptosis in cell culture. 759 98

The effect of co-inoculation of basement membrane matrix, Matrigel and two human breast cancer cell lines, BT-474 and SK-BR-3, was tested in immune-deficient mice. Both cell lines strongly overexpress c-ErbB-2 protein, whereas only BT-474 is reported to be oestrogen receptor positive. Co-inoculation of Matrigel and BT-474 cells but not of Matrigel and SK-BR-3 cells resulted in tumour formation in bg-nu-xid mice. Oestrogen supplementation greatly enhanced tumorigenicity, but did not seem to be an absolute requirement. In vivo, BT-474 cells grow as a poorly differentiated adenocarcinoma with a doubling time of 9.4 +/- 1.1 days after inoculation into the neck region. A high proliferative activity appears to be compensated by a relatively high rate of cell loss, as BT-474 tumours contain many cells with the typical morphology of apoptotic cell death. Wild-type p53, known to participate in the induction of apoptosis, is absent from the tumours, whereas Bcl-2, known to inhibit apoptosis, is expressed at intermediate levels. BT-474 tumours tend to metastasise to the regional lymph nodes and are capable of forming micrometastatic lesions in the lung. Flow cytometrical analysis of DNA ploidy demonstrated no change in tumours compared with the cell line. Immunohistochemical and flow cytometrical detection of a number of hormone and growth factor receptors, transcription factors, cell adhesion molecules and proteins involved in proliferation and cell death demonstrated no major changes in ploidy and phenotype of tumours compared with the cell line. High expression of the cell-surface molecules c-ErbB-2 and episialin make it a potentially useful model for research in immune therapy.
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PMID:Outgrowth of BT-474 human breast cancer cells in immune-deficient mice: a new in vivo model for hormone-dependent breast cancer. 759 56

The BAX gene is a member of the Bcl-2 gene family; it encodes a 21-kDa protein whose association with Bcl-2 is believed to play a critical role in regulating apoptosis. Through analysis of human-hamster somatic cell hybrid DNA and by in situ hybridization to metaphase chromosomes, we have determined that the human BAX gene is located in the q13.3-q13.4 region of human chromosome 19. We have also isolated a BAX cDNA clone in which that part of the mRNA encoded by exon 3 is absent. The skipping of exon 3 and the resultant splicing of exons 2 and 4 maintains the original reading frame and predicts the existence of an interstitially truncated form of the major Bax protein (Bax alpha), termed Bax delta. Unlike two previously described variant forms of Bax alpha (Bax beta and Bax tau), Bax delta retains the functionally critical C-terminal membrane anchor region as well as the Bcl-2 homology 1 and 2 (BH1 and BH2) domains.
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PMID:Mapping of the human BAX gene to chromosome 19q13.3-q13.4 and isolation of a novel alternatively spliced transcript, BAX delta. 760 85

The adenovirus E1A oncogene products stimulate DNA synthesis and cell proliferation but fail to transform primary baby rat kidney (BRK) cells because of the induction of p53-mediated programmed cell death (apoptosis). Overexpression of dominant mutant p53 (to abrogate wild-type p53 function) or introduction of apoptosis inhibitors, such as adenovirus E1B 19K or Bcl-2 oncoproteins, prevents E1A-induced apoptosis and permits transformation of BRK cells. The ability of activated Harvey-ras (H-ras) to cooperate with E1A to transform BRK cells suggests that H-ras is capable of overcoming the E1A-induced, p53-dependent apoptosis. We demonstrate here that activated H-ras was capable of suppressing apoptosis induced by E1A and wild-type p53. However, unlike Bcl-2 and the E1B 19K proteins, which completely block apoptosis but not p53-dependent growth arrest, H-ras expression permitted DNA synthesis and cell proliferation in the presence of high levels of wild-type p53. The mechanism by which H-ras regulates apoptosis and cell cycle progression is thereby strikingly different from that of the E1B 19K and Bcl-2 proteins. BRK cells transformed with H-ras and the temperature sensitive murine mutant p53(val 135), which lack E1A, underwent growth arrest at the permissive temperature for wild-type p53. p53-dependent growth arrest, however, could be relieved by E1A expression. Thus, H-ras alone was insufficient and cooperation of H-ras and E1A was required to override growth suppression by p53. Our data further suggest that two complementary growth signals from E1A plus H-ras can rescue cell death and thus permit transformation.
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PMID:Activated H-ras rescues E1A-induced apoptosis and cooperates with E1A to overcome p53-dependent growth arrest. 762 44

Programmed cell death (PCD) is a physiological process commonly defined by alterations in nuclear morphology (apoptosis) and/or characteristic stepwise degradation of chromosomal DNA occurring before cytolysis. However, determined characteristics of PCD such as loss in mitochondrial reductase activity or cytolysis can be induced in enucleated cells, indicating cytoplasmic PCD control. Here we report a sequential disregulation of mitochondrial function that precedes cell shrinkage and nuclear fragmentation. A first cyclosporin A-inhibitable step of ongoing PCD is characterized by a reduction of mitochondrial transmembrane potential, as determined by specific fluorochromes (5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolcarbocyanine++ + iodide; 3,3'dihexyloxacarbocyanine iodide). Cytofluorometrically purified cells with reduced mitochondrial transmembrane potential are initially incapable of oxidizing hydroethidine (HE) into ethidium. Upon short-term in vitro culture, such cells acquire the capacity of HE oxidation, thus revealing a second step of PCD marked by mitochondrial generation of reactive oxygen species (ROS). This step can be selectively inhibited by rotenone and ruthenium red yet is not affected by cyclosporin A. Finally, cells reduce their volume, a step that is delayed by radical scavengers, indicating the implication of ROS in the apoptotic process. This sequence of alterations accompanying early PCD is found in very different models of apoptosis induction: glucocorticoid-induced death of lymphocytes, activation-induced PCD of T cell hybridomas, and tumor necrosis factor-induced death of U937 cells. Transfection with the antiapoptotic protooncogene Bcl-2 simultaneously inhibits mitochondrial alterations and apoptotic cell death triggered by steroids or ceramide. In vivo injection of fluorochromes such as 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolcarbocyanine iodide; 3,3'dihexyloxacarbocyanine iodide; or HE allows for the detection of cells that are programmed for death but still lack nuclear DNA fragmentation. In particular, assessment of mitochondrial ROS generation provides an accurate picture of PCD-mediated lymphocyte depletion. In conclusion, alterations of mitochondrial function constitute an important feature of early PCD.
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PMID:Sequential reduction of mitochondrial transmembrane potential and generation of reactive oxygen species in early programmed cell death. 762 99

E1A of human adenovirus type 5 (Ad5) encodes proteins of 289 and 243 residues (289R and 243R) which differ only by the 46 amino acid CR3 region known to activate expression of certain cellular and early viral genes. E1A proteins also induce DNA synthesis and cell transformation, but as well can stimulate apoptosis. Two adenovirus E1B products act to protect cells from E1A-induced cell death, including a 19 kDa protein which is functionally similar to the cellular Bcl-2 suppressor of apoptosis, and a 55 kDa species which binds to and inhibits p53. Previous studies suggested that E1A-induced cell death occurs via a p53-dependent mechanism requiring regions of E1A proteins linked to induction of DNA synthesis and cell transformation. We report here that the 289R E1A protein induces apoptosis in cell lines lacking p53, whereas the 243R product was dependent upon p53. We also show that this p53-independent process involves the expression of one or more additional viral proteins which are presumably synthesized in response to transactivation by 289R. Thus E1A proteins induce cell death by both p53-dependent and p53-independent mechanisms involving separate E1A functions.
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PMID:Adenovirus E1A proteins induce apoptosis by both p53-dependent and p53-independent mechanisms. 763 Jun 30

Apoptosis seems to be involved in different stages of immune cell development. In particular, experimental evidence suggests that it is a major form of cell death in the thymus. The present analysis of human thymocytes reveals that a fraction of these cells, cultured in vitro, undergoes spontaneous apoptosis. This observation is based both on molecular (DNA fragmentation) and morphological (electron microscopic) investigations of the cells. The apoptotic thymocytes are CD3- or CD3lo, CD4lo, and CD8lo and do not express Bcl-2 protein. Furthermore, thymocytes die by apoptosis when exposed to pharmacological stimuli, such as tumor necrosis factor-alpha, dexamethasone, ATP, or Ca++ ionophore. Thus the apoptotic machinery in thymocytes can be triggered by an imbalance in growth factors in the in vitro culture media and can be modulated by various biochemical signals. The process of spontaneous apoptosis is independent of mRNA or protein synthesis, as actinomycin D and cycloheximide fail to inhibit this phenomenon. Furthermore, apoptosis seems to require active oxidative phosphorylation, as it is prevented by incubation of the cells with inhibitors of the respiratory chain.
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PMID:Spontaneous apoptosis in human thymocytes. 763 36

Mechanisms of etoposide (VP-16) resistance have been evaluated in a human promyelocytic leukemia HL60 cell line. HL60 resistant (HL60/AR) cells were selected for resistance with adriamycin and were 250-fold resistant to VP-16. We have found that while a significantly higher (10 to 15-fold more) dose of VP-16 was required to induce similar amounts of SDS-KCI-precipitable DNA-protein complex formation in the resistant cell line, there was no difference in the repair of VP-16-induced DNA damage, indicating that differential DNA repair was not involved in VP-16 resistance in HL60 cells. VP-16 treatment significantly inhibited c-myc expression and induced c-jun and c-fos expressions in sensitive cells. In contrast, VP-16 had no effect on c-myc, c-jun or c-fos expressions in resistant cells. The level of bcl2 oncogene was similar in both cell lines; however, treatment with VP-16 resulted in a time- and dose-dependent degradation of the genomic DNA into oligo-sized DNA only in the sensitive cells, indicating that differential expressions of oncogenes (c-myc, c-jun, and c-fos) and susceptibility to apoptosis may play important roles in the sensitivity and resistance to VP-16 in HL60 cells.
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PMID:Differential oncogene expression and susceptibility to apoptosis in the human leukemia HL60 cell lines: implications for etoposide resistance. 764 49


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