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

Galectin-1, a beta-galactoside-binding protein expressed at sites of T-cell activation and immune privilege, has shown specific immunosuppressive properties. Because of the implications of this protein in T-cell tolerance and its potential use to avoid graft rejection, we investigated the immunosuppressive effects of galectin-1 in the course of the human allogenic T-cell response. Galectin-1 induced a dose- and carbohydrate-dependent inhibition of the allogenic T-cell response. Addition of galectin-1 to alloreactive lymphocytes resulted in significant apoptosis of CD45R0-positive cells. This negative regulatory effect was accompanied by caspase activation, Bcl-2 downregulation and was prevented by addition of exogenous IL-2. In addition, a significant decrease of IFN-gamma production was detected in the non-apoptotic cell population, following exposure of alloreactive lymphocytes to galectin-1. Moreover, the immunosuppressive activity of this protein did not involve TGF-beta-mediated mechanisms. Since galectin-1 is expressed by activated T cells and could be acting by an autocrine negative loop to control human T-cell reactivity, we finally examined the regulated expression of this protein throughout the allogenic T-cell response. Expression of endogenous galectin-1 was detected at 24 h of cell culture, reaching its maximal levels after 72 h of allostimulation. The present study sets the basis for a potential use of galectin-1 as a selective immunosuppressive agent to limit T-cell-mediated reactivity during the effector phase of the alloimmune response.
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PMID:Induction of allogenic T-cell hyporesponsiveness by galectin-1-mediated apoptotic and non-apoptotic mechanisms. 1203 75

We studied the expression of Bcl-2 family proteins during cytokine- and verotoxin (VT)-induced apoptosis in primary human umbilical vein endothelial cells (HUVECs). Our experiments demonstrated that high initial expression of Bcl-2 protein was significantly downregulated in HUVECs treated with IFN-gamma whereas TNF-alpha gave a less pronounced decrease in Bcl-2 level. Treatment with the combination of cytokines was more efficient in downregulating Bcl-2 protein. HUVECs pretreated with cytokines and incubated with VT gave a further significant decrease in Bcl-2 level. Simultaneous measurement of Bcl-xl level did not reveal any significant changes. Bax protein was upregulated in HUVECs stimulated with TNF-alpha alone or in combination with IFN-gamma. However, addition of VT did not give any further increase in Bax level suggesting that Bax upregulation is more important for cytokine- rather than VT-mediated apoptosis. Total endothelial cell growth factor deprivation gave a significant increase in apoptosis accompanied by a decrease of Bcl-2 in apoptotic cells while Bcl-xl and Bax levels were unaffected. Our data indicate that anti-apoptotic protein Bcl-2 and pro-apoptotic protein Bax are reciprocally regulated during apoptosis, whilst Bcl-xl is essentially unaffected. This implies that Bcl-2/Bax ratio rather than Bcl-xl controls apoptosis in primary endothelial cells.
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PMID:Modulation of Bcl-2 family proteins in primary endothelial cells during apoptosis. 1221 54

Bag-1 exerts powerful antiapoptotic effects by binding and stabilizing Bcl-2 and interacting with the tumor necrosis factor receptor type I-induced death signal. We examined the effects of overexpression of Bag-1 by ex vivo adenoviral gene transfer on cold (4 degrees C for 24 hr) ischemia/reperfusion (I/R) injury of rat livers. Treatment with adenoviral Bag-1 (Ad-Bag-1) significantly improved portal venous blood flow, increased bile production, and improved hepatic function in the ex vivo model of cold ischemia followed by isolated perfusion. Moreover, the survival of orthotopic liver grafts subjected to cold ischemia increased from 50% in Ad-betaGal-treated controls to 100% after Ad-Bag-1 therapy. This effect correlated with preserved hepatic architecture, improved liver function, and depressed infiltration by neutrophils. Furthermore, the activation of infiltrating T cells, as measured by CD25, IL-2, and IFN-gamma mRNA expression was markedly reduced in the Ad-Bag-1 group. Hence, gene therapy-induced Bag-1 overexpression prevented cold I/R injury in rat livers. These findings provide the rationale for refined novel treatment of donor livers and may ultimately improve the overall success of liver transplantation.
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PMID:Upregulation of Bag-1 by ex vivo gene transfer protects rat livers from ischemia/reperfusion injury. 1221 70

IL-12 is a pleiotropic cytokine that plays an important role in innate and adaptive immunity. IL-12 induces T cell proliferation and IFN-gamma secretion from activated T cells. It was also reported that IL-12 prevents apoptosis of CD4(+) T cells. However, the signaling mechanism that regulates these IL-12-induced responses is poorly understood yet. In this study, we demonstrated that IL-12 activates phosphatidylinositol 3-kinase (PI3K)/Akt pathway in murine CD4(+) T cells, and that this signaling pathway is required for IL-12-induced T cell proliferation and antiapoptotic function, but not for IFN-gamma induction. Through PI3K/Akt pathway, IL-12 up-regulates the expression of cell cycle-related molecule such as cyclin D3, and antiapoptotic molecules such as Bcl-2 and cellular inhibitors of apoptosis proteins-2, followed by down-regulation of active caspase-3. These results suggest that PI3K/Akt pathway is critical for mediating IL-12-induced CD4(+) T cell responses such as T cell proliferation and survival.
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PMID:IL-12 provides proliferation and survival signals to murine CD4+ T cells through phosphatidylinositol 3-kinase/Akt signaling pathway. 1224 55

Interactions between 4-1BB and its ligand, 4-1BBL, enhance CD8(+) T cell-mediated antiviral and antitumor immunity in vivo. However, mechanisms regulating the priming of CD8(+) T cell responses by 4-1BB remain unclear, particularly in humans. The 4-1BB receptor was undetectable on naive or resting human CD8(+) T cells and induced in vitro by TCR triggering. Naive cord blood cells were therefore primed in vitro against peptides or cellular antigens and then co-stimulated with 4-1BBL or agonistic antibodies. Co-stimulation enhanced effector function such as IFN-gamma production and cytotoxicity by augmenting numbers of antigen-specific and effector CD8(+) T cells. OKT3 responses also showed reduced cell death and revealed that the proliferation of CD8(+) T cells required two independently regulated events. One, the induction of IL-2 production, could be directly triggered by 4-1BB engagement on CD8(+) T cells in the absence of accessory cells. The other, expression of CD25, was induced with variable efficacy by accessory cells. Thus, suboptimal accessory cells and 4-1BB co-stimulation combined their effects to enhance IL-2 production and proliferation. Reduced apoptosis observed after co-stimulation in the presence of accessory cells correlated with increased levels of Bcl-X(L) in CD8(+) T cells, while Bcl-2 expression remained unchanged. Altogether, 4-1BB enhanced expansion, survival and effector functions of newly primed CD8(+) T cells, acting in part directly on these cells. As 4-1BB triggering could be protracted from the TCR signal, 4-1BB agonists may function through these mechanisms to enhance or rescue suboptimal immune responses.
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PMID:4-1BB co-stimulation enhances human CD8(+) T cell priming by augmenting the proliferation and survival of effector CD8(+) T cells. 1235 81

Vaccinia virus (VV) infects a broad range of host cells, and while it usually causes their lysis (i.e. necrosis), the nature of the cell-death phenomenon is not well understood. In this study, we show that VV induces apoptosis of cells of the murine macrophage line J774.G8, as revealed by morphological signs, DNA ladder formation, changes of mitochondrial membrane potential and annexin-V positivity. Apoptosis occurred in both untreated and IFN-gamma-pretreated macrophages, and could not be inhibited by aminoguanidine, a relatively specific inhibitor of inducible nitric oxide synthase. Inhibition of VV DNA synthesis and late gene expression by cytosine arabinoside also did not prevent apoptosis, while heat- or psoralen/UV-inactivated VV did not cause any apoptosis. Thus, VV early gene expression seems to be required for induction of apoptosis. At the cellular level, infection with VV induced a decrease in the levels of Bcl-x(L), an anti-apoptotic member of the Bcl-2 family. The importance of loss of Bcl-x(L) was demonstrated by prevention of VV-mediated apoptosis on expression of Bcl-2, a functional homologue of Bcl-x(L). Our findings provide evidence that induction of apoptosis by VV in macrophages requires virus early gene expression, does not involve nitric oxide, induces a decrease in mitochondrial membrane potential and is associated with altered levels of Bcl-x(L).
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PMID:Vaccinia virus induces apoptosis of infected macrophages. 1238 19

T lymphocyte survival, proliferation, and death in the periphery are dependent on several cytokines. Many of these cytokines induce the expression of suppressor of cytokine signaling-1 (SOCS1), a feedback inhibitor of JAK kinases. However, it is unclear whether the cytokines that regulate T lymphocyte homeostasis are critically regulated by SOCS1 in vivo. Using SOCS1(-/-)IFN-gamma(-/-) mice we show that SOCS1 deficiency causes a lymphoproliferative disorder characterized by decreased CD4/CD8 ratio due to chronic accumulation of CD8+CD44(high) memory phenotype T cells. SOCS1-deficient CD8+ T cells express elevated levels of IL-2Rbeta, show increased proliferative response to IL-15 and IL-2 in vitro, and undergo increased bystander proliferation and vigorous homeostatic expansion in vivo. Sorted CD8+CD44(high) T cells from SOCS1(-/-)IFN-gamma(-/-) mice respond 5 times more strongly than control cells, indicating that SOCS1 is a critical regulator of IL-15R signaling. Consistent with this idea, IL-15 stimulates sustained STAT5 phosphorylation in SOCS1-deficient CD8+ T cells. IL-15 strongly induces TNF-alpha production in SOCS1-deficient CD8+ T cells, indicating that SOCS1 is also a critical regulator of CD8+ T cell activation by IL-15. However, IL-15 and IL-2 induce comparable levels of Bcl-2 and Bcl-x(L) in SOCS1-deficient and SOCS1-sufficient CD8+ T cells, suggesting that cytokine receptor signals required for inducing proliferation and cell survival signals are not identical. These results show that SOCS1 differentially regulates common gamma-chain cytokine signaling in CD8+ T cells and suggest that CD8+ T cell homeostasis is maintained by distinct mechanisms that control cytokine-mediated survival and proliferation signals.
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PMID:Suppressor of cytokine signaling 1 regulates IL-15 receptor signaling in CD8+CD44high memory T lymphocytes. 1292 91

Host nonspecific beta cell injury by cytokines has been implicated in the process of early islet graft dysfunction. Islet transplant destruction by cytokines released from inflammatory cells that infiltrate the graft is thought to be mainly mediated by NF-kappaB-dependent nitric oxide (NO) production by the islet. In this study, we aimed to evaluate the role of IL-6 in making a beta cell resistant to cytokine-induced apoptosis by decreasing the NF-kappaB-dependent NO production and compared the result with that of the expression of a dominant negative inhibitor of NF-kappaB (DN NF-kappaB). Incubation of MIN6 cells with IL-1beta, IFN-gamma, and TNF-alpha (cytomix) increased production of nitrites, with increased expression of iNOS mRNA. When treated with cytomix, the DN NF-kappaB-transfected mutant demonstrated significantly less nitrite production and apoptosis than parent MIN6. NO production was effectively blocked by IL-6 as well as by N-monomethyl-l-arginine (l-NMMA). Inhibition of the NO production led to decreased rate of apoptosis accompanied by downregulation of the proapoptotic molecule Bax and increased expression of the antiapoptotic molecule Bcl-2 and Bcl-x(L). These data indicate that cytokine-induced cell death in the MIN6 beta cell line involves mechanisms that are, in part, NF-kappaB- and NO-dependent. Inhibition of the NO production by the incubation of the MIN6 cells by the pretreatment of IL-6 or l-NMMA is cytoprotective and can be used as a substitute for the expression of DN NF-kappaB.
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PMID:Interleukin-6 protects MIN6 beta cells from cytokine-induced apoptosis. 1467 69

We have demonstrated previously a Fas-dependent component in thymineless death of human colon carcinoma cells. Importantly, the cytotoxic effects of thymidine deprivation induced by 5-fluorouracil (FUra) combined with leucovorin (LV) was enhanced by IFN-gamma, and the synergism was shown to be dependent on Fas, FUra-induced DNA damage, and independent of p53. Subsequently we examined the potential for synergistic interactions between IFN-gamma and the specific thymidylate synthase inhibitor, ZD9331. IFN-gamma sensitized colon carcinomas to ZD9331-induced apoptosis and loss in clonogenic survival, also dependent on ZD9331-induced DNA damage, independent of p53. Synergism occurred in HCT116, demonstrating previously RNA-mediated FUra/LV cytotoxicity that could not be potentiated by IFN-gamma. Manipulation of the Fas death receptor pathway from the level of the receptor (Nok1/Nok2, Fas overexpression, and DN-FADD) to the mitochondria (Bcl-xL and Bcl-2) did not modulate ZD9331 +/- IFN-gamma-induced cytotoxicity in HT29, with the exception that Nok1/Nok2-blocking antibodies partially protected HT29 from the cytotoxic activity of ZD9331 alone. However, IFN-gamma alone (but not ZD9331) up-regulated the expression of caspases -3, -4, -7, and -8, and in combination with ZD9331 demonstrated enhanced caspase activation and cleavage of poly(ADP-ribose) polymerase that was not prevented by overexpression of Bcl-2. Additionally, IFN-gamma increased the activity of the proteasome in HT29, leading to selective down-regulation of the antiapoptotic protein survivin, whereas simultaneously increasing Fas expression. However, reduction in the survivin:Fas ratio by transfection of survivin small interfering RNA and/or overexpression of Fas did not affect sensitivity of HT29 to ZD9331 +/- IFN-gamma. Data demonstrate that IFN-gamma combined with ZD9331 is synergistic in additional cell lines that demonstrate RNA-mediated FUra/LV cytotoxicity, and that a major target of interaction is at the level of caspases, downstream of Fas, and independent of involvement of either the mitochondria or survivin.
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PMID:Interferon-gamma-induced sensitization of colon carcinomas to ZD9331 targets caspases, downstream of Fas, independent of mitochondrial signaling and the inhibitor of apoptosis survivin. 1469 55

Liver injury induced by ischemia/reperfusion (I/R) is the prime factor in delayed or loss graft function following transplantation. CD4+ T lymphocytes are key cellular mediators of antigen-independent inflammatory response triggered by I/R. We attempted to modulate rat liver I/R injury by targeted gene therapy with CD40Ig, which blocks the CD40-CD154 costimulation pathway. One hundred percent of Ad-CD40Ig-pretreated orthotopic liver transplants (OLTs) subjected to 24 h of cold (4 degrees C) ischemia survived > 14 days (vs 50% in untreated/Ad-beta-gal groups). Ad-CD40Ig treatment decreased sGOT levels and depressed neutrophil infiltration, compared with controls. These functional data correlated with histological Suzuki's grading of hepatic injury, which in untreated/Ad-beta-gal groups showed severe necrosis (> 60%) and moderate to severe sinusoidal congestion; the Ad-CD40Ig-pretreated group revealed minimal sinusoidal congestion/necrosis. Unlike in controls, OLT expression of mRNA coding for IL-2/IFN-gamma remained depressed, whereas that of IL-4/IL-13 reciprocally increased in the Ad-CD40Ig group. Ad-CD40Ig reduced frequency of TUNEL+ cells and pro-apoptotic Caspase-3, but enhanced antioxidant HO-1 and anti-apoptotic Bcl-2/Bcl-xl expression. Thus, prolonged blockade of CD40-CD154 by CD40Ig exerts potent cytoprotection against hepatic I/R injury. These results provide the rationale for a novel gene therapy approach to maximize the organ donor pool through the safer use of liver transplants exposed to prolonged cold ischemia.
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PMID:Gene therapy for liver transplantation using adenoviral vectors: CD40-CD154 blockade by gene transfer of CD40Ig protects rat livers from cold ischemia and reperfusion injury. 1474 76


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