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Query: UNIPROT:P10415 (Bcl-2)
 33,771 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The molecular mechanisms regulating epidermal differentiation and apoptosis have not been elucidated. Bcl-2, one of the candidate genes for suppressing apoptosis, was originally cloned from the breakpoint of at (14;18) translocation present in many human B cell lymphomas. In this study, the influence of bcl-2 on apoptosis was observed in transfected keratinocytes. After transfection of pEF-BOS vector with/without bcl-2, the expression of coded protein and the viability under starved conditions were examined. The bcl-2-transfected keratinocytes had cytoplasmic positive staining with anti-bcl-2 monoclonal antibodies, however the vector only transfected cells were devoid of the reaction products. The viability of transfected keratinocytes under starved conditions, with a lack of epidermal growth factor and bovine pituitary extract, was maintained in bcl-2 transfected cells; while the vector only transfected cells showed apoptotic cell death. The present result indicates that bcl-2 suppresses apoptotic cell death under starved conditions due to a lack of epidermal growth factor and bovine pituitary extract.
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PMID:Enhanced expression of bcl-2 inhibits apoptosis in cultured human keratinocytes. 866 1

Mammary epithelial cells (MEC) undergo programmed cell death (PCD) when deprived of serum and growth factors at high cell density but not at low density. The addition of epidermal growth factor and insulin to serum-free medium (SFM) completely restores cell survival. In this report, we examine the role of cell-cell and cell-matrix interaction. When cell attachment is prevented, PCD is markedly accelerated. This effect is observed in cells collected at low or high density and is unaffected by calcium depletion. Cells plated in SFM on purified laminin, tenascin C, or collagen IV-coated dishes, as well as on dishes coated with endogenous extracellular matrix deposited by HC11 mammary cells, show reduced PCD. The addition of soluble laminin or tenascin C to suspension cultures of MECs also partially inhibits PCD. In contrast, no effect is seen with fibronectin or collagen I. These results indicate that reduced contact with a solid substrate contributes to the induction of PCD, which might partially explain the fact that it is only observed in confluent cultures. Ectopic Bcl-2 expression in MCF-10-A and HC11 mammary cells results in a complete suppression of PCD. In MCF-10-A cells, the level of endogenous Bcl-2 increases when the survival factors epidermal growth factor and insulin are added to the SFM but is unaffected by cell density. On the contrary, Bax protein expression increases sharply with cell density but does not change upon addition of epidermal growth factor and insulin. When compared to lactating tissue, Bcl-2 protein levels decrease during mammary gland involution. Bax protein levels increase during lactation and remain high during involution. These data suggest that Bcl-2 and Bax might be intracellular mediators of signals that influence MEC apoptosis.
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PMID:Apoptosis is accompanied by changes in Bcl-2 and Bax expression, induced by loss of attachment, and inhibited by specific extracellular matrix proteins in mammary epithelial cells. 904 Sep 47

Resolution of glomerular inflammation requires the removal of proliferating resident glomerular mesangial cells, but excessive loss of glomerular cells is a feature of postinflammatory scarring. Because apoptosis regulates mesangial cell number in glomerular inflammation, we have studied the exogenous control of apoptosis triggered in cultured mesangial cells by stimuli likely to be important in vivo. Apoptosis could be induced by serum deprivation to model decreased availability of survival factors, by etoposide as an example of DNA-damaging agents, by ligation of mesangial cell Fas, and by protein synthesis inhibition by cycloheximide. Insulin-like growth factor I (IGF-I), IGF-II, and basic fibroblast growth factor were each able to suppress apoptosis induced by serum deprivation, whereas TGF-beta 1, epidermal growth factor, and platelet-derived growth factor had no effect. IGF-I and IGF-II (but not basic fibroblast growth factor) were also able to protect cells from apoptosis induced by etoposide or cycloheximide. However, Fas-mediated apoptosis was resistant to suppression by all three cytokines. None of the cytokines tested caused a change in the levels of expression of Bcl-2, Bax, Bcl-x, or Bak proteins. The survival-promoting properties of serum-free medium conditioned by mesangial cells was abrogated by neutralizing IGF-I Ab. These experiments are the first to define cytokines that inhibit apoptosis and thereby promote survival of mesangial cells, and the data indicate a paracrine survival signaling role for IGF-I. Finally, the data show that Fas ligation can override cytokine survival signaling, emphasizing a candidate role for this molecule in the undesirable apoptotic loss of mesangial cells during the progression of glomerular scarring.
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PMID:Cytokines promote glomerular mesangial cell survival in vitro by stimulus-dependent inhibition of apoptosis. 937 83

Cytokines such as IL-2 or IL-3 prevent cell death through apoptosis, either by preventing apoptosis directly or by sensitizing cells to survival factors present in serum. We demonstrate herein that BAF-B03 cells transfected with the wild-type IL-2R beta-chain undergo apoptosis when stimulated with IL-2 or IL-3 in the absence of serum. IL-2 also induced apoptosis in normal IL-2-responsive human T cell blasts in the absence of serum, and furthermore, epidermal growth factor and fibroblast growth factor induced increased rates of apoptosis in fibroblasts in the absence of serum, suggesting that cytokine-induced apoptosis in the absence of serum survival factors might represent an important biologic phenomenon. In the presence or the absence of serum, IL-2 and IL-3 induced expression of both c-Myc and Bax. In contrast, optimal cytokine-induced expression of Bcl-2 requires serum. Constitutive expression of Bcl-2 prevented cytokine-induced apoptosis. Transferrin mimicked serum by inducing an increase in Bcl-2 expression levels and concurrently prevented apoptosis. These results suggest that the balance between cytokine- and serum-induced Bcl-2 expression and cytokine-induced Bax expression may determine whether a cell undergoes cytokine-induced apoptosis. In BAF/BO3 cells expressing a mutant IL-2Rbeta with a deletion of the acidic domain, IL-2 did not induce either Bax expression or apoptosis. This suggests that the acidic domain of the IL-2R beta-chain plays an essential role in regulating IL-2-mediated Bax expression and apoptosis. Cytokine-induced apoptosis and its counterbalance by survival factors present in serum may play an important role in the regulation of cellular homeostasis during pathophysiologic processes.
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PMID:Dissociation of cytokine signals for proliferation and apoptosis. 954 71

Signaling through the epidermal growth factor receptor (EGFR) has been primarily implicated in the growth of epithelial cells including keratinocytes. However, the mechanism by which EGFR stimulation promotes keratinocyte cell growth is poorly understood. Here we report that human keratinocytes undergo apoptosis when incubated with the blocking EGFR monoclonal antibody 225 IgG, or PD153035, a highly specific EGFR tyrosine kinase inhibitor. Endogenous mRNA and protein levels of Bcl-XL, a member the Bcl-2 family which suppresses apoptosis, were specifically inhibited by EGFR blockade. Furthermore, stimulation of EGFR signaling through two natural ligands, transforming growth factor (TGF)-alpha and epidermal growth factor (EGF), increased the expression of Bcl-XL in quiescent keratinocytes and HaCaT cells. Finally, ectopic expression of Bcl-XL in HaCaT cells increased survival after EGFR blockade when compared to untransfected cells or HaCaT keratinocytes transfected with empty vector. These results suggest that the anti-apoptotic protein Bcl-XL plays an important role in the maintenance of keratinocyte survival in response to EGFR signaling.
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PMID:EGF receptor signaling inhibits keratinocyte apoptosis: evidence for mediation by Bcl-XL. 958 Jan 12

Uterine leiomyoma is the most common smooth muscle cell tumor of the myometrium. Estrogen and progesterone (P4) are believed to be physiological regulators of leiomyoma growth. We recently showed that Bcl-2 protein, an apoptosis-inhibiting gene product, was abundantly expressed in leiomyoma relative to its expression in the normal myometrium and that Bcl-2 protein expression in cultured leiomyoma cells was up-regulated by P4, but down-regulated by 17 beta-estradiol (E2). To further characterize the molecular mechanism of sex steroidal regulation of leiomyoma growth, we examined the effect of menstrual phase on proliferating cell nuclear antigen (PCNA) expression in leiomyoma and investigated whether sex steroids could influence PCNA expression in leiomyoma cells cultured under serum-free conditions by immunoblot and immunohistochemical analyses. As epidermal growth factor (EGF) has been shown to mediate estrogen action and to play a crucial role in regulating leiomyoma growth, we also investigated the effects of sex steroids on the expression of EGF and EGF receptor (EGF-R) in cultured leiomyoma cells. The PCNA labeling index in leiomyomas was much greater in the secretory, P4-dominated, phase than in the proliferative phase of the menstrual cycle and was significantly higher than that in the adjacent normal myometrium throughout the menstrual cycle. In monolayer cultures of leiomyoma cells, the addition of either E2 (10 ng/mL) or P4 (100 ng/mL) resulted in an increase in PCNA expression in the cells compared to that in control cultures, whereas in monolayer cultures of myometrial cells, the addition of E2 augmented PCNA expression in the cells, but P4 did not. Immunoblot analysis of proteins extracted from cultured leiomyoma cells revealed that leiomyoma cells contained immunoreactive EGF with a molecular mass of 133 kDa and that the addition of P4 resulted in a remarkable increase in the expression of 133- and 71-kDa immunoreactive EGF in the cells compared to that in control cultures, whereas the addition of E2 resulted in a somewhat lower expression of immunoreactive EGF in the cells. Furthermore, immunocytochemical analysis with a monoclonal antibody to human EGF-R demonstrated that the treatment with E2 augmented EGF-R expression in the cells compared to that in untreated cells, but P4 did not. The concentrations of sex steroids used were within the physiological tissue concentrations found in leiomyomas and myometria. These results indicate that P4 up-regulates the expression of PCNA and immunoreactive EGF in leiomyoma cells, whereas E2 up-regulates the expression of PCNA and EGF-R in those cells. As it is evident that EGF plays a crucial role as a local factor in regulating leiomyoma growth, the P4-induced increase in PCNA expression in leiomyoma cells may be mediated by P4-induced enhanced expression of EGF-like proteins in the cells, whereas the E2-induced increase in PCNA expression in leiomyoma cells may be mediated by E2-induced enhanced expression of EGF-R in those cells. It is, therefore, conceivable that P4 and E2 act in combination to stimulate the proliferative potential of leiomyoma cells through the induction of EGF-like proteins and EGF-R expression in uterine leiomyoma.
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PMID:Up-regulation by progesterone of proliferating cell nuclear antigen and epidermal growth factor expression in human uterine leiomyoma. 962 59

Stat3, a member of STAT, is activated by a variety of cytokines such as IL-6 family of cytokines, granulocyte CSF, epidermal growth factor, and leptin. A recent study with mice genetically deficient in the Stat3 gene has revealed its important role in the early embryogenesis. To assess the function of Stat3 in adult tissues, we disrupted the Stat3 gene specifically in T cells by conditional gene targeting using Cre-loxP system. In Stat3-deficient T cells, IL-6-induced proliferation was severely impaired. IL-6 did not enhance cell cycle progression, but prevented apoptosis of normal T cells. In contrast, IL-6 did not prevent apoptosis of Stat3-deficient T cells. Antiapoptotic protein, Bcl-2, was normally up-regulated in response to IL-6 even in Stat3-deficient T cells. These results demonstrate that Stat3 activation is involved in IL-6-dependent T cell proliferation through prevention of apoptosis independently of Bcl-2.
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PMID:Stat3 activation is responsible for IL-6-dependent T cell proliferation through preventing apoptosis: generation and characterization of T cell-specific Stat3-deficient mice. 2579 90

The aim of this review is to summarize the interactions between the oocyte and its surrounding granulosa cells which are involved in the control of oocyte growth or apoptosis as well as those playing a key role in the ability of the oocyte to undergo nuclear (resumption as meiosis to reach the MII stage) or cytoplasmic maturation (ability to fertilize and develop to the blastocyst stage). The respective roles of the oocyte and of the granulosa cells in controlling the initiation of growth are poorly understood. During the preantral follicular stage when most oocyte growth is achieved, a local regulation appears to be in operation involving growth factors such as fibroblast growth factor (FGF) or epidermal growth factor/transforming growth factor alpha (EGF/TGF alpha), together with two proteins (c-kit present on the oocyte's membrane and its ligand KL produced by granulosa cells). In-situ techniques used to detect apoptosis demonstrate apoptotic oocytes in the reserves of primordial follicles but seldom within preantral follicles (because it is too fast?). Proteins involved in cell death (bax) or cell survival (bcl2) are present in oocytes as well as compounds (TNF alpha, Fas) involved in the initiation of apoptosis. However, the molecular and cellular mechanisms triggering oocyte apoptosis are not fully clarified. Three approaches have been used to identify compounds which are relevant to the oocyte's nuclear or cytoplasmic maturation. a) Correlation between amounts of specific compounds in follicular fluid or within follicle cells and the oocyte's ability to mature. b) Analysis of the consequences of pharmacological disruption of mechanisms such as steroidogenesis on oocyte maturation. c) Analysis of the consequences of addition of graded amounts of specific compounds on oocyte maturation in defined media. Factors playing a key role in stimulating nuclear maturation appear to be epidermal growth factor (EGF) and the inhibin (cattle)/activin (rodents) family, while testosterone has an inhibitory effect. Cytoplasmic maturation of the oocyte appears to be stimulated by oestradiol, EGF and inhibin.
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PMID:Control of oocyte growth and maturation by follicular cells and molecules present in follicular fluid. A review. 979 80

SFME cells are brain-derived neural precursor cells that are acutely dependent on epidermal growth factor (EGF) for survival, undergoing apoptosis within 24 h after EGF withdrawal. Because the expression of the protooncogene bcl-2 inhibits apoptosis induced by the withdrawal of interleukins or nerve growth factor in some growth factor-dependent haematopoietic or neuronal cell cultures, we examined the effect of Bcl-2 expression on cell death of SFME cells in the absence of EGF. SFME cells expressing human Bcl-2 showed prolonged survival when deprived of EGF compared to control cells not expressing Bcl-2. A significant fraction of Bcl-2-expressing cells remained viable for 4 days in the absence of EGF and resumed proliferation upon readdition of EGF to the cultures. These results suggest that apoptosis induced by EGF withdrawal in SFME cells may share common mechanisms with other growth factor-related apoptotic systems.
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PMID:Bcl-2 inhibits cell death of serum-free mouse embryo cells caused by epidermal growth factor deprivation. 987 29

For the past decade, an attempt has been made by many research groups to define the roles of the growing number of Bcl-2 gene family proteins in the apoptotic process. The Bcl-2 family consists of pro-apoptotic (or cell death) and anti-apoptotic (or cell survival) genes and it is the balance in expression between these gene lineages that may determine the death or survival of a cell. The majority of studies have analysed the role/s of the Bcl-2 genes in cancer development. Equally important is their role in normal tissue development, homeostasis and non-cancer disease states. Bcl-2 is crucial for normal development in the kidney, with a deficiency in Bcl-2 producing such malformation that renal failure and death result. As a corollary, its role in renal disease states in the adult has been sought. Ischaemia is one of the most common causes of both acute and chronic renal failure. The section of the kidney that is most susceptible to ischaemic damage is the outer zone of the outer medulla. Within this zone the proximal tubules are most sensitive and often die by necrosis or desquamate. In the distal nephron, apoptosis is the more common form of cell death. Recent results from our laboratory have indicated that ischaemia-induced acute renal failure is associated with up-regulation of two anti-apoptotic Bcl-2 proteins (Bcl-2 and Bcl-XL) in the damaged distal tubule and occasional up-regulation of Bax in the proximal tubule. The distal tubule is a known reservoir for several growth factors important to renal growth and repair, such as insulin-like growth factor-1 (IGF-1) and epidermal growth factor (EGF). One of the likely possibilities for the anti-cell death action of the Bcl-2 genes is that the protected distal cells may be able to produce growth factors that have a further reparative or protective role via an autocrine mechanism in the distal segment and a paracrine mechanism in the proximal cells. Both EGF and IGF-1 are also up-regulated in the surviving distal tubules and are detected in the surviving proximal tubules, where these growth factors are not usually synthesized. As a result, we have been using in vitro methods to test: (i) the relative sensitivities of renal distal and proximal epithelial cell populations to injury caused by mechanisms known to act in ischaemia-reperfusion; (ii) whether a Bcl-2 anti-apoptotic mechanism acts in these cells; and (iii) whether an autocrine and/or paracrine growth factor mechanism is initiated. The following review discusses the background to these studies as well as some of our preliminary results.
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PMID:Bcl-2 genes and growth factors in the pathology of ischaemic acute renal failure. 1036 Dec 61


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