Bcl-2 is an inner mitochondrial membrane protein that blocks programmed cell death
TL;DR: It is demonstrated that Bcl-2 is an integral inner mitochondrial membrane protein of relative molecular mass 25,000 (25k) being localized to mitochondria and interfering with programmed cell death independent of promoting cell division.
Abstract: The t(14; 18) chromosomal translocation of human follicular B-cell lymphoma juxtaposes the bcl-2 gene with the immunoglobulin heavy chain locus. The bcl-2 immunoglobulin fusion gene is markedly deregulated resulting in inappropriately elevated levels of bcl-2 RNA and protein. Transgenic mice bearing a bcl-2 immunoglobulin minigene demonstrate a polyclonal expansion of resting yet responsive IgM-IgD B cells which display prolonged cell survival but no increase in cell cycling. Moreover, deregulated bcl-2 extends the survival of certain haematopoietic cell lines following growth-factor deprivation. By using immunolocalization studies we now demonstrate that Bcl-2 is an integral inner mitochondrial membrane protein of relative molecular mass 25,000 (25k). Overexpression of Bcl-2 blocks the apoptotic death of a pro-B-lymphocyte cell line. Thus, Bcl-2 is unique among proto-oncogenes, being localized to mitochondria and interfering with programmed cell death independent of promoting cell division.
Citations
More filters
TL;DR: In multicellular organisms, homeostasis is maintained through a balance between cell proliferation and cell death, and recent evidence suggests that alterations in cell survival contribute to the pathogenesis of a number of human diseases.
Abstract: In multicellular organisms, homeostasis is maintained through a balance between cell proliferation and cell death. Although much is known about the control of cell proliferation, less is known about the control of cell death. Physiologic cell death occurs primarily through an evolutionarily conserved form of cell suicide termed apoptosis. The decision of a cell to undergo apoptosis can be influenced by a wide variety of regulatory stimuli. Recent evidence suggests that alterations in cell survival contribute to the pathogenesis of a number of human diseases, including cancer, viral infections, autoimmune diseases, neurodegenerative disorders, and AIDS (acquired immunodeficiency syndrome). Treatments designed to specifically alter the apoptotic threshold may have the potential to change the natural progression of some of these diseases.
6,462 citations
TL;DR: Overexpressed Bax accelerates apoptotic death induced by cytokine deprivation in an IL-3-dependent cell line and counters the death repressor activity of B cl-2, suggesting a model in which the ratio of Bcl-2 to Bax determines survival or death following an apoptotic stimulus.
6,193 citations
Cites background or methods from "Bcl-2 is an inner mitochondrial mem..."
...CL1 6 and CL23 of the established HA-Baxa clones were cotransfected with a spleen focusforming virus hBcl-2 vector (Hockenbery et al., 1990) and an expression vector (LAP 267) providing a hygromycin selection marker (Bairn et al....
[...]
...Bcl-2 Coprecipitates with a 21 kd Protein Coimmunoprecipitation experiments were performed utilizing the 6C6 monoclonal antibody (MAb) that is specific for human 6~1-2 (Hockenbery et al., 1990)....
[...]
...Bcl-2 conferred a death-sparing effect to certain hematopoietic cell lines following growth factor withdrawal (Vaux et al., 1988; Hockenbery et al., 1990; Nuriez et al., 1990)....
[...]
...Antibodies 6C8 human B&P-specific hamster MAb (Hockenbery et al., 1990) 12CA5 influenza virus hemagglutinin protein epitope-specific murine MAb (Kolodziej and Young, 1991) and 3Fll murine Bcl-2-specific hamster MAb (veis et al....
[...]
...In the absence of IL-3, FL512 dies by apoptosis, but overexpression of Bcl-2 extends its survival (Hockenbery et al., 1990; Nufiez et al., 1990)....
[...]
TL;DR: The effects of dominant-interfering or constitutively activated forms of various components of the JNK-p38 and ERK signaling pathways demonstrated that activation of JNK and p38 and concurrent inhibition of ERK are critical for induction of apoptosis in these cells.
Abstract: Apoptosis plays an important role during neuronal development, and defects in apoptosis may underlie various neurodegenerative disorders. To characterize molecular mechanisms that regulate neuronal apoptosis, the contributions to cell death of mitogen-activated protein (MAP) kinase family members, including ERK (extracellular signal-regulated kinase), JNK (c-JUN NH2-terminal protein kinase), and p38, were examined after withdrawal of nerve growth factor (NGF) from rat PC-12 pheochromocytoma cells. NGF withdrawal led to sustained activation of the JNK and p38 enzymes and inhibition of ERKs. The effects of dominant-interfering or constitutively activated forms of various components of the JNK-p38 and ERK signaling pathways demonstrated that activation of JNK and p38 and concurrent inhibition of ERK are critical for induction of apoptosis in these cells. Therefore, the dynamic balance between growth factor-activated ERK and stress-activated JNK-p38 pathways may be important in determining whether a cell survives or undergoes apoptosis.
5,398 citations
TL;DR: The identification of critical control points in the cell death pathway has yielded fundamental insights for basic biology, as well as provided rational targets for new therapeutics.
4,741 citations
Cites background from "Bcl-2 is an inner mitochondrial mem..."
...The cellular organelle for a prominent role in apoptosis (Hockenbery et al., 1990)....
[...]
01 Jan 2000
TL;DR: This annex is aimed at providing a sound basis for conclusions regarding the number of significant radiation accidents that have occurred, the corresponding levels of radiation exposures and numbers of deaths and injuries, and the general trends for various practices, in the context of the Committee's overall evaluations of the levels and effects of exposure to ionizing radiation.
Abstract: NOTE The report of the Committee without its annexes appears as Official Records of the General Assembly, Sixty-third Session, Supplement No. 46. The designations employed and the presentation of material in this publication do not imply the expression of any opinion whatsoever on the part of the Secretariat of the United Nations concerning the legal status of any country, territory, city or area, or of its authorities, or concerning the delimitation of its frontiers or boundaries. The country names used in this document are, in most cases, those that were in use at the time the data were collected or the text prepared. In other cases, however, the names have been updated, where this was possible and appropriate, to reflect political changes. Scientific Annexes Annex A. Medical radiation exposures Annex B. Exposures of the public and workers from various sources of radiation INTROdUCTION 1. In the course of the research and development for and the application of atomic energy and nuclear technologies, a number of radiation accidents have occurred. Some of these accidents have resulted in significant health effects and occasionally in fatal outcomes. The application of technologies that make use of radiation is increasingly widespread around the world. Millions of people have occupations related to the use of radiation, and hundreds of millions of individuals benefit from these uses. Facilities using intense radiation sources for energy production and for purposes such as radiotherapy, sterilization of products, preservation of foodstuffs and gamma radiography require special care in the design and operation of equipment to avoid radiation injury to workers or to the public. Experience has shown that such technology is generally used safely, but on occasion controls have been circumvented and serious radiation accidents have ensued. 2. Reviews of radiation exposures from accidents have been presented in previous UNSCEAR reports. The last report containing an exclusive chapter on exposures from accidents was the UNSCEAR 1993 Report [U6]. 3. This annex is aimed at providing a sound basis for conclusions regarding the number of significant radiation accidents that have occurred, the corresponding levels of radiation exposures and numbers of deaths and injuries, and the general trends for various practices. Its conclusions are to be seen in the context of the Committee's overall evaluations of the levels and effects of exposure to ionizing radiation. 4. The Committee's evaluations of public, occupational and medical diagnostic exposures are mostly concerned with chronic exposures of …
3,924 citations
References
More filters
TL;DR: Results argue that bcl-2 provided a distinct survival signal to the cell and may contribute to neoplasia by allowing a clone to persist until other oncogenes, such as c-myc, become activated.
Abstract: A common feature of follicular lymphoma, the most prevalent haematological malignancy in humans, is a chromosome translocation (t(14;18] that has coupled the immunoglobulin heavy chain locus to a chromosome 18 gene denoted bcl-2. By analogy with the translocated c-myc oncogene in other B-lymphoid tumours bcl-2 is a candidate oncogene, but no biological effects of bcl-2 have yet been reported. To test whether bcl-2 influences the growth of haematopoietic cells, either alone or together with a deregulated c-myc gene, we have introduced a human bcl-2 complementary DNA using a retroviral vector into bone marrow cells from either normal or E mu-myc transgenic mice, in which B-lineage cells constitutively express the c-myc gene. Bcl-2 cooperated with c-myc to promote proliferation of B-cell precursors, some of which became tumorigenic. To determine how bcl-2 expression impinges on growth factor requirements, the gene was introduced into a lymphoid and a myeloid cell line that require interleukin 3 (IL-3). In the absence of IL-3, bcl-2 promoted the survival of the infected cells but they persisted in a G0 state, rather than proliferating. These results argue that bcl-2 provided a distinct survival signal to the cell and may contribute to neoplasia by allowing a clone to persist until other oncogenes, such as c-myc, become activated.
3,238 citations
TL;DR: In this paper, a DNA probe was obtained from an acute B-cell leukemia cell line, which was specific for chromosome 18 and flanked the heavy chain joining region of the immunoglobulin heavy chain locus on chromosome 14.
Abstract: From an acute B-cell leukemia cell line, a DNA probe was obtained that was specific for chromosome 18 and flanked the heavy chain joining region of the immunoglobulin heavy chain locus on chromosome 14. This probe detected rearrangement of the homologous DNA segment in the leukemic cells and in follicular lymphoma cells with the t(14:18) chromosome translocation but not in other neoplastic or normal B or T cells. The probe appears to identify bcl-2, a gene locus on chromosome 18 (band q21) that is unrelated to known oncogenes and may be important in the pathogenesis of B-cell neoplasms with this translocation.
1,702 citations
TL;DR: The data confirm that the condensed chromatin which characterizes apoptosis morphologically consists of endogenously digested chromatin fragments, and provide support for the view that at least some cells enter apoptosis by a process dependent upon macromolecular synthesis.
Abstract: In glucocorticoid-treated rat thymocytes and the murine lymphoid cell lines L5178 and S49 the morphology of apoptosis is associated with chromatin cleavage. The cleavage is at internucleosomal sites, apparently through activation of an endogenous endonuclease. In variants of the cell lines selected for resistance to glucocorticoid, neither apoptosis nor chromatin cleavage were observed after steroid treatment, and steroid receptors were undetectable. In thymocytes, both the morphological changes of apoptosis and chromatin cleavage were inhibited by cycloheximide and actinomycin D. The calcium-magnesium ionophore A23187 induced apoptosis and chromatin cleavage in thymocytes, and these effects were also inhibited by cycloheximide. The data confirm that the condensed chromatin which characterizes apoptosis morphologically consists of endogenously digested chromatin fragments. They also provide support for the view that at least some cells enter apoptosis by a process dependent upon macromolecular synthesis.
1,588 citations
TL;DR: The results suggest that t(14;18) translocations alter expression of the bcl-2 gene both by transcriptional activation and by abnormal posttranscriptional regulation of bCl-2 mRNA.
1,260 citations
TL;DR: In this article, minigene constructs representing the bcl-2-Ig fusion gene found at this chromosomal breakpoint were placed into the germ line of mice to assess the effects of the t(14;18) interchromosomal translocation during development.
1,260 citations