Physical and functional interaction of CARMA1 and CARMA3 with Ikappa kinase gamma-NFkappaB essential modulator.
(17/240)
CARMA proteins are scaffold molecules that contain a caspase recruitment domain and a membrane-associated guanylate kinase-like domain. CARMA1 plays a critical role in mediating activation of the NFkappaB transcription factor following antigen receptor stimulation of both B and T lymphocytes. However, the biochemical mechanism by which CARMA1 regulates activation of NFkappaB remains to be determined. Here we have shown that CARMA1 and CARMA3 physically associate with Ikappa kinase gamma/NFkappaB essential modulator (IkappaKgamma-NEMO) in lymphoid and non-lymphoid cells. CARMA1 participates to an inducible large molecular complex that contains IkappaKgamma/NEMO, Bcl10, and IkappaKalpha/beta kinases. Expression of the NEMO-binding region of CARMA3 exerts a dominant negative effect on Bcl10-mediated activation of NFkappaB. Thus, our results provide direct evidence for physical and functional interaction between CARMA and the IkappaK complex and offer a biochemical framework to understand the molecular activities controlled by CARMA-1, -2, and -3 and Bcl10. (+info)
Ipaf is upregulated by tumor necrosis factor-alpha in human leukemia cells.
(18/240)
Ipaf has been associated with apoptosis, cytokine processing, and nuclear factor-kappaB activation. Here, we describe that Ipaf is highly expressed in myelomonocytic cells and that the mRNA levels of Ipaf progressively increase during differentiation of CD34(+) progenitors to granulocytes and monocytes. Additionally, treatment with tumor necrosis factor-alpha and exposure to UV radiation induced the transcriptional activation of Ipaf in human leukemia HL-60 cells. Thus, Ipaf may contribute to modulate the response of myeloid cells to genotoxic and pro-inflammatory stimuli. (+info)
Multiple roles of CLAN (caspase-associated recruitment domain, leucine-rich repeat, and NAIP CIIA HET-E, and TP1-containing protein) in the mammalian innate immune response.
(19/240)
NAIP CIIA HET-E and TP1 (NACHT) family proteins are involved in sensing intracellular pathogens or pathogen-derived molecules, triggering host defense responses resulting in caspase-mediated processing of proinflammatory cytokines and NF-kappaB activation. Caspase-associated recruitment domain, leucine-rich repeat, and NACHT-containing protein (CLAN), also known as ICE protease-activating factor, belongs to a branch of the NACHT family that contains proteins carrying caspase-associated recruitment domains (CARDs) and leucine-rich repeats (LRRs). By using gene transfer and RNA-interference approaches, we demonstrate in this study that CLAN modulates endogenous caspase-1 activation and subsequent IL-1beta secretion from human macrophages after exposure to LPS, peptidoglycan, and pathogenic bacteria. CLAN was also found to mediate a direct antibacterial effect within macrophages after Salmonella infection and to sensitize host cells to Salmonella-induced cell death through a caspase-1-independent mechanism. These results indicate that CLAN contributes to several biological processes central to host defense, suggesting a prominent role for this NACHT family member in innate immunity. (+info)
PDK1 nucleates T cell receptor-induced signaling complex for NF-kappaB activation.
(20/240)
Activation of the transcription factor NF-kappaB after engagement of the T cell receptor (TCR) is important for T cell proliferation and activation during the adaptive immune response. Recent reports have elucidated a signaling pathway that involves the protein kinase C (PKC), the scaffold protein CARD11 (also called CARMA-1), the caspase recruitment domain (CARD)-containing protein Bcl10, and the paracaspase (protease related to caspases) MALT1 as critical intermediates linking the TCR to the IkappaB kinase (IKK) complex. However, the events proximal to the TCR that initiate the activation of this signaling pathway remain poorly defined. We demonstrate that 3-phosphoinositide-dependent kinase 1 (PDK1) has an essential role in this pathway by regulating the activation of PKC and through signal-dependent recruiting of both PKC and CARD11 to lipid rafts. PDK1-associated PKC recruits the IKK complex, whereas PDK1-associated CARD11 recruits the Bcl10-MALT1 complex, thereby allowing activation of the IKK complex through Bcl10-MALT1-dependent ubiquitination of the IKK complex subunit known as NEMO (NF-kappaB essential modifier). Hence, PDK1 plays a critical role by nucleating the TCR-induced NF-kappaB activation pathway in T cells. (+info)
Effects of parathyroid hormone like hormone (PTHLH) antagonist, PTHLH(7-34), on fetoplacental development and growth during midgestation in rats.
(21/240)
Parathyroid hormone-like hormone (PTHLH) secretion has been reported in human amnion, chorion, decidual cytotrophoblast, syncytiotrophoblast, endometrium, and myometrium; however, the functions of PTHLH during pregnancy, particularly during placenta formation and fetal development, are not well understood. We examined whether neutralization of PTHLH action using PTHLH antagonist, PTHLH(7-34), in rats during early gestation affects fetal and placental growth. Rats received s.c. a daily dose of either 0, 4, 12, or 36 microg of PTHLH(7-34) infused continuously through mini-osmotic pumps from Day 8 through Day 15 of pregnancy. Fetal weights measured on Day 15 were significantly decreased in rats treated with all the doses of PTHLH(7-34) compared to controls, and decreases in placental weights were significant at the 12-microg dose. TUNEL assay demonstrated an increased number of apoptotic cells in placenta of treated rats, including rats treated with the 4-microg dose. Cleaved caspase 3 (CASP3), caspase 9 (CASP9) (P < 0.05) and poly-ADP-ribose polymerase (PARP1) (P < 0.01) expression was increased and BCL2 (P < 0.01) expression was decreased in rats treated with 4 microg PTHLH(7-34) compared to that in control. Placental cytochrome c expression was increased (P < 0.01) in cytosolic and decreased (P < 0.01) in mitochondrial fraction in PTHLH(7-34)-treated rats. Caspase 8 expression was not affected by the treatment. Immunohistochemical analysis of platelet endothelial cell adhesion molecule (PECAM1) showed higher staining intensity in control than in treated rats. In conclusion, these results suggests that PTHLH plays a role in early pregnancy, and that antagonization of PTHLH action causes fetoplacental growth restriction through activation of mitochondrial pathway of apoptosis in the placenta and through decreased expression of PECAM1. (+info)
Overexpression of caspase recruitment domain (CARD) membrane-associated guanylate kinase 1 (CARMA1) and CARD9 in primary gastric B-cell lymphoma.
(22/240)
BACKGROUND: Although caspase recruitment domain (CARD) membrane-associated guanylate kinase (MAGUK) protein 1 (CARMA1) and CARD9 play important roles in lymphocyte activation, the significance of CARMA1 and CARD9 in the pathogenesis of gastric mucosa-associated lymphoid tissue (MALT) lymphoma remains to be elucidated. METHODS: By using reverse transcription-polymerase chain reaction analysis, the expression levels of mRNA of CARMA1, CARD9, Bcl10, and the apoptosis inhibitor 2 (API2)-MALT1 chimeric transcript were determined in tissue specimens from 65 patients with primary gastric B-cell lymphoma (43 patients with low-grade MALT lymphoma, 16 patients with MALT lymphoma plus diffuse large B-cell lymphoma [DLBL], and 6 patients with DLBL without MALT lymphoma) and in tissue specimens from 18 patients with chronic gastritis. The expression levels of CARMA1 and BCL10 were examined immunohistochemically in 30 patients with lymphoma. RESULTS: CARMA1 mRNA was detected in 55% of lymphoma patients but in only 17% of chronic gastritis patients. The positive rates for CARD9, Bcl10, and API2-MALT1 chimeric transcript in the lymphoma patients were 48%, 98%, and 8%, respectively, whereas the 3 molecules were not detected in any specimens from patients with chronic gastritis. The expression of CARMA1 and CARD9 was frequent in the Helicobacter pylori-negative patients (100% and 86%, respectively), in the API2-MALT1 chimeric transcript-positive patients (100% and 100%, respectively), and in the specimens from patients who did not respond to H. pylori eradication (76% and 71%, respectively). In addition, CARMA1 expression was positive more frequently in patients of DLBL without MALT lymphoma (100%) than in patients of MALT lymphoma (51%). CARMA1 protein expression was correlated significantly with the expression of CARMA1 mRNA and also with the expression of nuclear BCL10. CONCLUSIONS: The overexpression of CARMA1 and CARD9 presumably is associated with the development or progression of gastric B-cell lymphoma, especially among patients who have disease in which the pathogenesis is not related to H. pylori. (+info)
A novel isoform of TUCAN is overexpressed in human cancer tissues and suppresses both caspase-8- and caspase-9-mediated apoptosis.
(23/240)
Caspase-associated recruitment domains (CARD) are protein-protein interaction modules found extensively in proteins that play important roles in apoptosis. One of the CARD-containing proteins, TUCAN (CARD8), was reported previously as an antiapoptotic protein with a molecular weight of 48 kDa, which was up-regulated in colon cancer cells. We identified a novel isoform of TUCAN with a molecular weight of 54 kDa. The new variant of TUCAN, termed TUCAN-54, was expressed in gastric, colon, and breast cancer tissues but was barely detected in normal noncancerous tissues, whereas 48-kDa TUCAN was detected in tumor tissues and noncancerous tissues. To know the function of TUCAN-54 in the apoptosis of cancer cells, TUCAN-54 was overexpressed in tumor cells by gene transfection. Its overexpression inhibited pro-caspase-9 activation, leading to the suppression of the cell death induced by a protein kinase inhibitor, staurosporine, or a chemotherapeutic reagent, etoposide (VP-16). In contrast, specific small interfering RNA-mediated suppression of TUCAN-54 expression in tumor cells increased the VP-16-induced cell death rate, indicating that expression of TUCAN-54 might be associated with chemoresistance of tumor cells. In addition, it inhibited caspase-8 activation as well, thereby suppressing Fas-induced cell death. It was revealed that Fas-associated death domain was physically associated with TUCAN-54 but not with 48-kDa TUCAN. Thus, TUCAN-54 might be a novel tumor-specific antiapoptotic molecule expressed in a variety of human cancer tissues, which might aggravate malignant potential of cancer cells, such as chemoresistance and immunoresistance. (+info)
PKC beta regulates BCR-mediated IKK activation by facilitating the interaction between TAK1 and CARMA1.
(24/240)
The B cell antigen receptor (BCR)-mediated activation of IkappaB kinase (IKK) and nuclear factor-kappaB require protein kinase C (PKC)beta; however, the mechanism by which PKCbeta regulates IKK is unclear. Here, we demonstrate that another protein kinase, TGFbeta-activated kinase (TAK)1, is essential for IKK activation in response to BCR stimulation. TAK1 interacts with the phosphorylated CARMA1 (also known as caspase recruitment domain [CARD]11, Bimp3) and this interaction is mediated by PKCbeta. IKK is also recruited to the CARMA1-Bcl10-mucosal-associated lymphoid tissue 1 adaptor complex in a PKCbeta-dependent manner. Hence, our data suggest that phosphorylation of CARMA1, mediated by PKCbeta, brings two key protein kinases, TAK1 and IKK, into close proximity, thereby allowing TAK1 to phosphorylate IKK. (+info)