NF-κB-mediated up-regulation of Bcl-x and Bfl-1/A1 is required for CD40 survival signaling in B lymphocytes

Lee, Ho H.; Dadgostar, Hajir; Cheng, Qingwen; Shu, Junyan; Cheng, Genhong

doi:10.1073/pnas.96.16.9136

Cited by 493 publications

(364 citation statements)

References 43 publications

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“…Other groups have confirmed this work in a variety of cell types, including cancer cells 59,398,399 . However at the protein level they have had to use tagged protein due to the lack of high quality commercial antibodies for Bfl-1, and to our knowledge, this regulation has never been confirmed in melanoma cells.…”

Section: Determination Of the Signalling Pathways Important In Bfl-1 supporting

confidence: 65%

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Role of the pro-survival molecule Bfl-1 in melanoma

Hind

Carter

Harris

et al. 2015

The International Journal of Biochemistry & Cell Biology

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Melanoma, the cancer derived from the melanocytes of the skin, is becoming an ever more common cancer in the ageing population of the developed world and displays an intrinsic resistance to current therapies. This chemo resistance makes metastatic melanoma an extremely difficult cancer to treat leading to a 5 year survival rate of just 20%. As such, it is important to unearth new potential drug targets to increase the prospects for melanoma patients.Bfl-1 is a pro-survival protein of the Bcl-2 family of apoptosis regulating proteins. It has been found to be over-expressed in a small subset of chemo resistant tumours, including melanoma. Accordingly, I characterised the molecule in melanoma cells and determined its role in protecting these cells from chemotherapy-induced apoptosis. I elucidated the expression profile and half-lives of the protein and mRNA across a panel of melanoma cell-lines and healthy melanocytes. I also confirmed, using pathway specific inhibitors, that Bfl-1 was transcriptionally regulated by the NFB pathway and concluded through pulsechase experiments that Bfl-1 protein was degraded, at least in part, by the proteasome. Subcellular fractionation and indirect immunofluorescence techniques elucidated that Bfl-1 was located mostly at the mitochondria in both resting and apoptotic cells, with a diffuse level present throughout the cytoplasm. As well as characterising the protein in both melanoma cells and healthy primary melanocytes, I determined its role in the resistance of these cells to apoptosis. Over-expressed Bfl-1 was found to protect melanoma cells from apoptosis caused by a range of chemotherapeutic agents in A375 melanoma cells, which naturally expressed very low levels of Bfl-1. Further, knock down of Bfl-1 using siRNA technology in melanoma cells revealed the dependence of these cells on Bfl-1 for their resistance to certain chemotherapeutic agents currently used in melanoma treatment, including the MEK inhibitor PD901. All together, this research contributes to our understanding of Bfl-1 and highlights it as a potentially important therapeutic target in metastatic melanoma.

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Section: Determination Of the Signalling Pathways Important In Bfl-1 supporting

confidence: 65%

“…Bfl-1 has been shown to be up-regulated in response to a range of apoptotic stimuli through the NFB pathway 59,235,398,399 . It has been determined to be a direct transcriptional target of NFB with an NFB binding site in the promoter region of the gene, which is also found in the Bcl-x promoter 400 .…”

Section: The Regulation Of Bfl-1mentioning

confidence: 99%

Role of the pro-survival molecule Bfl-1 in melanoma

Hind

Carter

Harris

et al. 2015

The International Journal of Biochemistry & Cell Biology

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“…CD40-mediated activation of NF-jB was reported to be required for long-term protection from CD95 apoptosis, by up-regulating cellular inhibitors of apoptosis (cIAP), FLIP, Bcl-xL and Bfl-1/A1 or Gadd45b [17][18][19][20]. However, we find here that CD40 signaling can protect B cells from CD95 apoptosis at very early time points after stimulation.…”

Section: Introductioncontrasting

confidence: 61%

“…When CD95 is oligomerized, either by binding to its ligand on T cells (CD95L) or by Ab against its extracellular domain, it recruits the adaptor molecule Fas-associated death domain-containing protein (FADD) and procaspase 8 into a complex called the deathinducing signaling complex (DISC) that cleaves procaspase 8 to the active form [12][13][14][15]. Active caspase 8 cleaves and activates the effector caspase 3, which dismantles the cell by cleaving proteins essential for cell survival, including poly(ADP) polymerase, and activating pro-apoptotic molecules, such as DNAses and Bcl-2 interacting potein (Bid) [16].CD40-mediated activation of NF-jB was reported to be required for long-term protection from CD95 apoptosis, by up-regulating cellular inhibitors of apoptosis (cIAP), FLIP, Bcl-xL and Bfl-1/A1 or Gadd45b [17][18][19][20]. However, we find here that CD40 signaling can protect B cells from CD95 apoptosis at very early time points after stimulation.…”

mentioning

confidence: 99%

“…3E). This is the first report that CD40 signaling can inhibit CD95-induced caspase activation in B cells.Independence of CD40-mediated early rescue signals from NF-jB activation and de novo protein synthesis NF-jB is a pro-survival transcription factor that has been implicated in CD40 protection from apoptosis [19,20,[28][29][30]. Because the classical (NF-jB1) pathway is activated by CD40 much earlier than the NF-jB2 pathway, experiments were performed to determine whether CD40-mediated CD95 rescue requires NF-jB1 activation [31].…”

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confidence: 99%

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Rapid CD40‐mediated rescue from CD95‐induced apoptosis requires TNFR‐associated factor‐6 and PI3K

Benson

Hostager²,

Bishop

2006

Eur J Immunol

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The activation molecule CD40 and the death receptor CD95/Fas play important roles in regulating B cells so that effective antimicrobial immunity occurs without autoimmunity. CD40 signaling increases CD95 expression, sensitizing cells to apoptosis, but sustained CD40 signals rescue B cells from CD95 killing. Here we describe a mechanism of early CD40-mediated rescue from CD95-induced apoptosis in B cells. Maximal rescue was achieved when CD40 signals were given within 1-2 h of initiating CD95 apoptosis. CD40 signaling did not block association of Fas-associated death domain-containing protein with CD95, but decreased CD95-induced activation of caspases 3 and 8. Rapid CD40 rescue did not require NF-jB activation and was independent of de novo protein synthesis, but was dependent upon active PI3 K. Signaling via a CD40 mutant that does not bind TNFR-associated factor (TRAF)1, TRAF2, and TRAF3 rescued B cells from CD95-induced apoptosis. TRAF1/2/3-independent rescue was confirmed in B cell lines made deficient in these TRAF molecules by gene targeting. In contrast, CD40 rescue was completely abrogated in TRAF6-deficient B cells, which showed reduced activation of Akt in response to CD40 engagement. These results reveal a new rapid mechanism to balance B cell activation and apoptosis. IntroductionB cells integrate many signals that direct proliferation and differentiation into Ig-secreting plasma cells or longlived memory cells. Ultimately, activated B cells can be eliminated through apoptosis, which is important for maintaining immune tolerance and homeostasis [1,2]. Molecules of the TNFR family play critical roles in regulating the balance between B cell activation and apoptosis. CD40 signals allow B cells to proliferate, differentiate, switch isotype, form GC, and become memory cells [3][4][5]. CD40 stimulation also induces upregulation of other members of the TNFR family, including the death receptor CD95/Fas [6].The importance of CD95 in maintaining lymphocyte homeostasis and tolerance is highlighted by the human disease autoimmune lymphoproliferative syndrome (ALPS), caused by mutations in the CD95 signaling pathway [7,8] autoantibodies are produced, and systemic autoimmunity develops [9]. Expression of the CD95 transgene exclusively in T cells of lpr/lpr mice is sufficient to decrease lymphadenopathy, splenomegaly, and the accumulation of abnormal T cells, but these mice still produce autoantibodies, causing deposition of immune complexes in kidney glomeruli [10]. In contrast, expression of the CD95 transgene in both B and T cells reduces the levels of serum Ig, autoimmune symptoms, and mortality [11]. Thus, CD95 signaling in B cells is crucial for maintaining peripheral tolerance and preventing autoimmunity. When CD95 is oligomerized, either by binding to its ligand on T cells (CD95L) or by Ab against its extracellular domain, it recruits the adaptor molecule Fas-associated death domain-containing protein (FADD) and procaspase 8 into a complex called the deathinducing signaling complex (DISC) that cleaves pro...

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Tumor necrosis factor‐α‐induced changes in insulin‐producing β‐cells

2005

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The migration of macrophages and lymphocytes that produce cytokines such as tumor necrosis factor-␣ (TNF-␣) causes ␤-cell death, leading to type 1 diabetes. Similarly, in type 2 diabetes, the adipocyte-derived cytokines including TNF-␣ are elevated in the circulation, causing inflammation and insulin resistance. Thus, the studies described in this article using TNF-␣ are relevant to furthering our understanding of the pathogenesis of diabetes mellitus. We used RINr1046-38 (RIN) insulin-producing ␤-cells, which constitutively express calbindin-D 28k , to characterize the effect of TNF-␣ on apoptosis, replication, insulin release, and gene and protein expression. ] i following the addition of 5.5 M ionomycin; increased by more than threefold the apoptotic rate, expressed as the percentage of TUNEL-positive nuclei to total nuclei; decreased the rate of cell replication by 36%; and increased and decreased selectively the expression of specific genes as determined by microarray analysis. The subcellular localizations of Bcl-2, an antiapoptotic protein, and Bax, a proapoptotic protein, within RIN cells were altered with TNF-␣ treatment such that the two were colocalized with mitochondria in the perinuclear region. We conclude that the proapoptotic action of TNF-␣ on ␤-cells is manifested via decreased expression of calbindin-D 28k and is mediated at least in part by [Ca 2ϩ ] i .

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NF-κB-mediated up-regulation of Bcl-x and Bfl-1/A1 is required for CD40 survival signaling in B lymphocytes

Abstract: ABSTRACT

Cited by 493 publications

References 43 publications

Role of the pro-survival molecule Bfl-1 in melanoma

Role of the pro-survival molecule Bfl-1 in melanoma

Rapid CD40‐mediated rescue from CD95‐induced apoptosis requires TNFR‐associated factor‐6 and PI3K

Tumor necrosis factor‐α‐induced changes in insulin‐producing β‐cells

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