The combination of gemcitabine and ginsenoside Rh2 enhances the immune function of dendritic cells against pancreatic cancer via the CARD9-BCL10-MALT1 / NF-κB pathway

Cold tumor immune microenvironment (TIME) of pancreatic cancer (PC) with minimal dendritic cell (DC) and T cell infiltration can result in insufficient immunotherapy and chemotherapy. While gemcitabine (GEM) is a first-line chemotherapeutic drug for PC, its efficacy is reduced by immunosuppression and drug resistance. Ginsenoside Rh2 (Rh2) is known to have anti-cancer and immunomodulatory properties. Combining GEM with Rh2 may thus overcome immunosuppression and induce lasting anti-tumor immunity in PC. Here, we showed that after GEM-Rh2 therapy, there was significantly greater tumor infiltration by DCs. Caspase recruitment domain-containing protein 9 (CARD9), a central adaptor protein, was strongly up-regulated DCs with GEM-Rh2 therapy and promoted anti-tumor immune responses by DCs. CARD9 was found to be a critical target for Rh2 to enhance DC function. However, GEM-Rh2 treatment did not achieve the substantial anti-PC efficacy in CARD9^-/- mice as in WT mice. The adoptive transfer of WT DCs to DC-depleted PC mice treated with GEM-Rh2 elicited strong anti-tumor immune responses, although CARD9^-/- DCs were less effective than WT DCs. Our results showed that GEM-Rh2 may reverse cold TIME by enhancing tumor immunogenicity and decreasing the levels of immunosuppressive factors, reactivating DCs via the CARD9-BCL10-MALT1/ NF-κB pathway. Our findings suggest a potentially feasible and safe treatment strategy for PC, with a unique mechanism of action. Thus, Rh2 activation of DCs may remodel the cold TIME and optimize GEM chemotherapy for future therapeutic use.

Augmented autophagy suppresses thymocytes development via Bcl10/p-p65 pathway in prenatal nicotine exposed fetal mice

Tobacco smoke is a common global environmental pollutant. Maternal tobacco smoke/nicotine exposure has long-term toxic effects on immune organs. We previously found that prenatal nicotine exposure (PNE)-induced programmed immune diseases caused by fetal thymic hypoplasia, but the mechanism still unknown. Autophagy has important functions in maintaining thymopoiesis, whether autophagy was involved in PNE-inhibited fetal thymocytes development is also obscure. Therefore, this study aimed to investigate how nicotine changed the development of fetal thymocytes from the perspective of autophagy in vivo and in vitro. PNE model was established by 3 mg/kg nicotine administration in Balb/c mice from gestational day 9 to 18. The results showed that PNE reduced the percentage and absolute number of CD69^-CD4⁺SP cells, suggesting a block of fetal thymocytes mature. PNE promoted autophagosome formation, autophagy related proteins (Beclin1, LC3I/II) expression, and upregulated α7 nAChR as well as AMPK phosphorylation in fetal thymus. Moreover, PNE promoted Bcl10 degradation via autophagy-mediated proteolysis and inhibited p65 activation, blocking the transition of thymocytes between the DP to SP stage. Further, primary thymocytes were treated with nicotine in vitro and showed induced autophagy in a dose- and time-dependent manner. In addition, nicotine-inhibited CD69^-CD4⁺SP cells and the Bcl10/p-p65 pathway have been reversed by an autophagy inhibitor. The α7 nAChR specific antagonist abrogated nicotine-induced AMPK phosphorylation and autophagy initiation. In conclusion, our findings showed that PNE repressed the Bcl10/p-p65 development pathway of CD4⁺SP cells by triggering autophagy, and illuminated the developmental origin mechanism of programmed immune diseases in PNE offspring.

Two Antagonistic MALT1 Auto-Cleavage Mechanisms Reveal a Role for TRAF6 to Unleash MALT1 Activation

The paracaspase MALT1 has arginine-directed proteolytic activity triggered by engagement of immune receptors. Recruitment of MALT1 into activation complexes is required for MALT1 proteolytic function. Here, co-expression of MALT1 in HEK293 cells, either with activated CARD11 and BCL10 or with TRAF6, was used to explore the mechanism of MALT1 activation at the molecular level. This work identified a prominent self-cleavage site of MALT1 isoform A (MALT1A) at R781 (R770 in MALT1B) and revealed that TRAF6 can activate MALT1 independently of the CBM. Intramolecular cleavage at R781/R770 removes a C-terminal TRAF6-binding site in both MALT1 isoforms, leaving MALT1B devoid of the two key interaction sites with TRAF6. A previously identified auto-proteolysis site of MALT1 at R149 leads to deletion of the death-domain, thereby abolishing interaction with BCL10. By using MALT1 isoforms and cleaved fragments thereof, as well as TRAF6 WT and mutant forms, this work shows that TRAF6 induces N-terminal auto-proteolytic cleavage of MALT1 at R149 and accelerates MALT1 protein turnover. The MALT1 fragment generated by N-terminal self-cleavage at R149 was labile and displayed enhanced signaling properties that required an intact K644 residue, previously shown to be a site for mono-ubiquitination of MALT1. Conversely, C-terminal self-cleavage at R781/R770 hampered the ability for self-cleavage at R149 and stabilized MALT1 by hindering interaction with TRAF6. C-terminal self-cleavage had limited impact on MALT1A but severely reduced MALT1B proteolytic and signaling functions. It also abrogated NF-κB activation by N-terminally cleaved MALT1A. Altogether, this study provides further insights into mechanisms that regulate the scaffolding and activation cycle of MALT1. It also emphasizes the reduced functional capacity of MALT1B as compared to MALT1A.

Targeting Non-proteolytic Protein Ubiquitination for the Treatment of Diffuse Large B Cell Lymphoma

Chronic active B cell receptor (BCR) signaling, a hallmark of the activated B cell-like (ABC) subtype of diffuse large B cell lymphoma (DLBCL), engages the CARD11-MALT1-BCL10 (CBM) adapter complex to activate IκB kinase (IKK) and the classical NF-κB pathway. Here we show that the CBM complex includes the E3 ubiquitin ligases cIAP1 and cIAP2, which are essential mediators of BCR-dependent NF-κB activity in ABC DLBCL. cIAP1/2 attach K63-linked polyubiquitin chains on themselves and on BCL10, resulting in the recruitment of IKK and the linear ubiquitin chain ligase LUBAC, which is essential for IKK activation. SMAC mimetics target cIAP1/2 for destruction, and consequently suppress NF-κB and selectively kill BCR-dependent ABC DLBCL lines, supporting their clinical evaluation in patients with ABC DLBCL.

CARMA3 Is a Host Factor Regulating the Balance of Inflammatory and Antiviral Responses against Viral Infection

Host response to RNA virus infection is sensed by RNA sensors such as RIG-I, which induces MAVS-mediated NF-κB and IRF3 activation to promote inflammatory and antiviral responses, respectively. Here, we have found that CARMA3, a scaffold protein previously shown to mediate NF-κB activation induced by GPCR and EGFR, positively regulates MAVS-induced NF-κB activation. However, our data suggest that CARMA3 sequesters MAVS from forming high-molecular-weight aggregates, thereby suppressing TBK1/IRF3 activation. Interestingly, following NF-κB activation upon virus infection, CARMA3 is targeted for proteasome-dependent degradation, which releases MAVS to activate IRF3. When challenged with vesicular stomatitis virus or influenza A virus, CARMA3-deficient mice showed reduced disease symptoms compared to those of wild-type mice as a result of less inflammation and a stronger ability to clear infected virus. Altogether, our results reveal the role of CARMA3 in regulating the balance of host antiviral and pro-inflammatory responses against RNA virus infection.

E1/E2 of Hepatitis C Virus Genotype4 and Apoptosis

Several studies have addressed the possible role of hepatitis C virus genotype4 (HCV GT4) in apoptosis. However, this still not fully understood. In the current study a reconstructed clone of E1/E2 polyprotein region of the HCV GT4 was transfected into the Huh7 cell line and a human apoptotic PCR array of 84 genes was used to investigate its possible significance for apoptosis. Out of the 84 genes, only 35 showed significant differential expression, 12 genes being upregulated and 23 downregulated. The highestup regulated genes were APAF1 (apoptotic peptidaseactivating factor 1), BID (BH3 interacting domain death agonist) and BCL 10 (Bcell CLL/ lymphoma protein 10) with fold regulation of 33.2, 30.1 and 18.9, respectively. The most downregulated were FAS (TNF receptor super family), TNFRSF10B (tumor necrosis factor receptor superfamily member 10b) and FADD (FASassociated death domain) with fold regulation of 30.2, 27.7 and 14.9, respectively. These results suggest that the E1/E2 proteins may be involved in HCVinduced pathogenesis by modulating apoptosis through the induction of the intrinsic apoptosis pathway and disruption of the BCL2 gene family.

Systems-wide analysis of BCR signalosomes and downstream phosphorylation and ubiquitylation

B-cell receptor (BCR) signaling is essential for the development and function of B cells; however, the spectrum of proteins involved in BCR signaling is not fully known. Here we used quantitative mass spectrometry-based proteomics to monitor the dynamics of BCR signaling complexes (signalosomes) and to investigate the dynamics of downstream phosphorylation and ubiquitylation signaling. We identify most of the previously known components of BCR signaling, as well as many proteins that have not yet been implicated in this system. BCR activation leads to rapid tyrosine phosphorylation and ubiquitylation of the receptor-proximal signaling components, many of which are co-regulated by both the modifications. We illustrate the power of multilayered proteomic analyses for discovering novel BCR signaling components by demonstrating that BCR-induced phosphorylation of RAB7A at S72 prevents its association with effector proteins and with endo-lysosomal compartments. In addition, we show that BCL10 is modified by LUBAC-mediated linear ubiquitylation, and demonstrate an important function of LUBAC in BCR-induced NF-κB signaling. Our results offer a global and integrated view of BCR signaling, and the provided datasets can serve as a valuable resource for further understanding BCR signaling networks.

Functional characterization of zebrafish (Danio rerio) Bcl10

The complexes formed by BCL10, MALT1 and specific members of the family of CARMA proteins (CBM complex), have recently focused much attention because they represent a central hub regulating activation of the transcription factor NF-κB following various cellular stimulations. In this manuscript, we report the functional characterization of a Danio rerio 241 amino acids polypeptide ortholog of the Caspase recruiting domain (CARD)-containing protein BCL10. Biochemical studies show that zebrafish Bcl10 (zBcl10) dimerizes and binds to components of the CBM complex. Fluorescence microscopy observations demonstrate that zBcl10 forms cytoplasmic filaments similar to that formed by human BCL10 (hBCL10). Functionally, in human cells zBcl10 is more effective in activating NF-κB compared to hBCL10, possibly due to the lack of carboxy-terminal inhibitory serine residues present in the human protein. Also, depletion experiments carried out through expression of short hairpin RNAs targeting hBCL10 indicate that zBcl10 can functionally replace the human protein. Finally, we show that the zebrafish cell line PAC2 is suitable to carry out reporter assays for monitoring the activation state of NF- kB transcription factor. In conclusion, this work shows that zebrafish may excellently serve as a model organism to study complex and intricate signal transduction pathways, such as those that control NF-κB activation.

Visualizing TCR-induced POLKADOTS formation and NF-κB activation in the D10 T-cell clone and mouse primary effector T cells

T cells are an immune cell lineage that play a central role in protection against pathogen infection. Antigen, in the form of pathogen-derived peptides, stimulates the T-cell receptor (TCR), leading to activation of the transcription factor, nuclear factor kappa B (NF-κB). The subsequent NF-κB-dependent gene expression program drives expansion and effector differentiation of antigen-specific T cells, leading to the adaptive anti-pathogen immune response. The cell surface TCR transmits activating signals to cytosolic NF-κB by a complex signaling cascade, in which the adapter protein Bcl10 plays a key role. We have previously demonstrated that TCR engagement leads to the formation of cytosolic Bcl10 clusters, called POLKADOTS, that provide a platform for the assembly of the terminal signaling complex that ultimately mediates NF-κB activation. In this chapter, we describe the methods utilized to visualize the formation of TCR-induced POLKADOTS and to study the temporal association between POLKADOTS formation and nuclear translocation of the NF-κB subunit, RelA/p65.

Inherited BCL10 deficiency impairs hematopoietic and nonhematopoietic immunity

Heterotrimers composed of B cell CLL/lymphoma 10 (BCL10), mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1), and caspase recruitment domain-containing (CARD) family adaptors play a role in NF-κB activation and have been shown to be involved in both the innate and the adaptive arms of immunity in murine models. Moreover, individuals with inherited defects of MALT1, CARD9, and CARD11 present with immunological and clinical phenotypes. Here, we characterized a case of autosomal-recessive, complete BCL10 deficiency in a child with a broad immunodeficiency, including defects of both hematopoietic and nonhematopoietic immunity. The patient died at 3 years of age and was homozygous for a loss-of-expression, loss-of-function BCL10 mutation. The effect of BCL10 deficiency was dependent on the signaling pathway, and, for some pathways, the cell type affected. Despite the noted similarities to BCL10 deficiency in mice, including a deficient adaptive immune response, human BCL10 deficiency in this patient resulted in a number of specific features within cell populations. Treatment of the patient's myeloid cells with a variety of pathogen-associated molecular pattern molecules (PAMPs) elicited a normal response; however, NF-κB-mediated fibroblast functions were dramatically impaired. The results of this study indicate that inherited BCL10 deficiency should be considered in patients with combined immunodeficiency with B cell, T cell, and fibroblast defects.

MALT1 auto-proteolysis is essential for NF-κB-dependent gene transcription in activated lymphocytes

Mucosa-associated lymphoid tissue 1 (MALT1) controls antigen receptor–mediated signalling to nuclear factor κB (NF-κB) through both its adaptor and protease function. Upon antigen stimulation, MALT1 forms a complex with BCL10 and CARMA1, which is essential for initial IκBα phosphorylation and NF-κB nuclear translocation. Parallel induction of MALT1 protease activity serves to inactivate negative regulators of NF-κB signalling, such as A20 and RELB. Here we demonstrate a key role for auto-proteolytic MALT1 cleavage in B- and T-cell receptor signalling. MALT1 cleavage occurred after Arginine 149, between the N-terminal death domain and the first immunoglobulin-like region, and did not affect its proteolytic activity. Jurkat T cells expressing an un-cleavable MALT1-R149A mutant showed unaltered initial IκBα phosphorylation and normal nuclear accumulation of NF-κB subunits. Nevertheless, MALT1 cleavage was required for optimal activation of NF-κB reporter genes and expression of the NF-κB targets IL-2 and CSF2. Transcriptome analysis confirmed that MALT1 cleavage after R149 was required to induce NF-κB transcriptional activity in Jurkat T cells. Collectively, these data demonstrate that auto-proteolytic MALT1 cleavage controls antigen receptor-induced expression of NF-κB target genes downstream of nuclear NF-κB accumulation.

CARMA3 is upregulated in human pancreatic carcinoma, and its depletion inhibits tumor proliferation, migration, and invasion

Elevated CARMA3 expression has been reported to be involved in tumor progression of several cancer types. In the present study, we examined the expression pattern of CARMA3 protein and its biological roles in human pancreatic carcinoma. Using immunohistochemistry, we checked CARMA3 protein expression in 95 pancreatic ductal carcinoma specimens. We found that CARMA3 was overexpressed in 34 of 95 (35.8 %) specimens. A significant association was observed between CARMA3 overexpression with histological grade (p=0.0099) and nodal status (p=0.0126). To further explore its biological roles, we knocked down CARMA3 expression in CAPAN2 cell line using small interfering RNA (siRNA). MTT growth assay, wound healing assay, and Transwell assay showed that CARMA3 depletion inhibited cell proliferation, migration, and invasion. We also showed that CARMA3 depletion inhibited EGF-induced nuclear factor-kappaB (NF-κB) activation and its target genes' expression. The effect of CARMA3 depletion on NF-κB signaling was significantly reduced in Bcl10-depleted cells. In conclusion, CARMA3 is overexpressed in pancreatic cancer and regulates malignant cell growth, invasion, and NF-κB signaling, which was dependent on its association with Bcl10.

Rad50-CARD9 interactions link cytosolic DNA sensing to IL-1β production

Double-stranded DNA (dsDNA) in the cytoplasm triggers the production of interleukin 1β (IL-1β) as an antiviral host response, and deregulation of the pathways involved can promote inflammatory disease. Here we report a direct cytosolic interaction between the DNA-damage sensor Rad50 and the innate immune system adaptor CARD9. Transfection of dendritic cells with dsDNA or infection of dendritic cells with a DNA virus induced the formation of dsDNA-Rad50-CARD9 signaling complexes for activation of the transcription factor NF-κB and the generation of pro-IL-1β. Primary cells conditionally deficient in Rad50 or lacking CARD9 consequently exhibited defective DNA-induced production of IL-1β, and Card9(-/-) mice had impaired inflammatory responses after infection with a DNA virus in vivo. Our results define a cytosolic DNA-recognition pathway for inflammation and a physical and functional connection between a conserved DNA-damage sensor and the innate immune response to pathogens.

Increased expression of Dec-205, Bcl-10, Tim-3, and Trem-1 mRNA in chronic otitis media with cholesteatoma

CONCLUSION

The increased expression of Dec-205, Bcl-10, Tim-3, and Trem-1 mRNAs indicates that these pattern recognition receptors are involved in the pathogenesis of cholesteatoma.

OBJECTIVE

Changes in expression of pattern recognition receptors may be associated with immune responses in patients with cholesteatoma. We therefore assessed the levels of expression of Dec-205, Bcl-10, Tim-3, and Trem-1 mRNAs associated with innate immune responses in patients with cholesteatoma.

METHODS

Cholesteatoma specimens were collected from 23 patients diagnosed with acquired cholesteatoma from August 2010 to July 2012. The posterior auricular skin of each patient was used as control. The levels of expression of Dec-205, Bcl-10, Tim-3, and Trem-1 mRNA were assessed quantitatively using real-time RT-PCR and correlated with sex, hearing level, the presence of bacteria, and the need for repeat surgery.

RESULTS

The levels of expression of Dec-205, Bcl-10, Tim-3, and Trem-1 mRNAs were significantly higher in cholesteatoma than in control skin samples (p < 0.05 each). However, mRNA abundance was not associated with patient sex, hearing level, presence of bacteria or history of reoperation (p > 0.05 each).

Bcl10 links saturated fat overnutrition with hepatocellular NF-kB activation and insulin resistance

Excess serum free fatty acids (FFAs) are fundamental to the pathogenesis of insulin resistance. With high-fat feeding, FFAs activate NF-kB in target tissues, initiating negative crosstalk with insulin signaling. However, the mechanisms underlying FFA-dependent NF-kB activation remain unclear. Here, we demonstrate that the saturated FA, palmitate, requires Bcl10 for NF-kB activation in hepatocytes. Uptake of palmitate, metabolism to diacylglycerol, and subsequent activation of protein kinase C (PKC) appear to mechanistically link palmitate with Bcl10, known as a central component of a signaling complex that, along with CARMA3 and MALT1, activates NF-kB downstream of selected cell surface receptors. Consequently, Bcl10-deficient mice are protected from hepatic NF-kB activation and insulin resistance following brief high-fat diet, suggesting that Bcl10 plays a major role in the metabolic consequences of acute overnutrition. Surprisingly, while CARMA3 also participates in the palmitate response, MALT1 is completely dispensable, thereby revealing an apparent nonclassical role for Bcl10 in NF-kB signaling.

Structural insights into the assembly of CARMA1 and BCL10

The CBM complex (CARMA1, BCL10 and MALT1) plays a crucial role in B and T lymphocyte activation. CARMA1 serves as a scaffold for BCL10, MALT1 and other effector proteins and regulates various signaling pathways related to the immune response. The assembly of CARMA1 and BCL10 is mediated through a CARD-CARD interaction. Here, we report the crystal structure of the CARD domain of CARMA1 at a resolution of 1.75 Å. The structure consists of six helices, as previously determined for CARD domains. Structural and computational analysis identified the binding interface between CARMA1-CARD and BCL10-CARD, which consists of a basic patch in CARMA1 and an acidic patch in BCL10. Site-directed mutagenesis, co-immunoprecipitation and an NF-κB activation assay confirmed that the interface is necessary for association and downstream signaling. Our studies provide molecular insight into the assembly of CARMA1 and BCL10.

BCL10 down-regulation in peripheral T-cell lymphomas

The BCL10 gene encodes for a T-cell receptor signaling downstream protein involved in nuclear factor κB activation. It is expressed in normal lymphoid tissues and in several B-non Hodgkin lymphomas, its aberrant function being related to the pathogenesis of certain subtypes. Conversely, conflicting data are available concerning BCL10 expression in peripheral T cell lymphomas. We analyzed BCL10 expression in peripheral T cell lymphomas and correlated it with NFκB activation, proliferation, phenotypic aberration, and survival. First, gene expression analysis of 40 peripheral T cell lymphomas (28 peripheral T cell lymphomas/not otherwise specified, 6 anaplastic large cell lymphomas, and 6 angioimmunoblastic lymphomas), 4 reactive lymph nodes, and 20 samples of normal T-lymphocytes, showed significantly lower BCL10 gene expression in all tumors in comparison to normal samples, the lowest values being detected in anaplastic large cell lymphoma. Secondly, we studied the immunohistochemical expression of BCL10 in 52 peripheral T cell lymphomas/not otherwise specified on tissue microarrays. BCL10 was expressed in 10/52 cases (19%), not showing any significant correlation with either expression of Ki-67 and the T-cell markers or NFκB activation. Furthermore, BCL10 expression was not associated with peculiar gene expression profiles. Finally, we did not find significant correlations with progression free survival and overall survival, although a favorable trend was recorded in BCL10(+) cases. In conclusion, BCL10 was commonly down-regulated in peripheral T cell lymphomas, suggest the T-cell receptor signaling cascade for future characterization.

Molecular Pathogenesis of Mucosal-Associated Lymphoid Tissue (MALT) Lymphoma

Extranodal marginal zone B-cell lymphomas of mucosal-associated lymphoid tissue (MALT)-type occur in a number of anatomic sites, but share overlapping morphological and immunophenotypic features. Helicobacter pylori infection has been identified as an etiological factor in gastric MALT lymphoma, but the cause of MALT lymphomas at other sites remains a matter of speculation. Despite these limitations in understanding the etiology of MALT lymphoma, standard cytogenetic analysis has proved useful by demonstrating similar alterations in MALT lymphomas from different anatomic sites. The common cytogenetic alterations that characterize MALT lymphomas include t(11:18)(q21:q21), t(1;14)(p22;q32) and, more recently, t(14;18)(q32;q21). The apparent complexity of the cytogenetic alterations that have now been implicated in the pathogenesis of extranodal MALT lymphoma serves as a paradigm for molecular cross talk in neoplastic disease. Recent data have shown that these very disparate translocations affect a common signaling mechanism, and thus unify all three under a common pathogenesis, resulting in the constitutive activation of the NF-kappaB pathway.

CD4 ligation excludes the Carma1-Bcl10-MALT1 complex from GM1-positive membrane rafts in CD3/CD28 activated T cells

The antibody 13B8.2, which is directed against the CDR3-like loop on the D1 domain of CD4, induces CD4/ZAP-70 reorganization and ceramide release in membrane rafts. Here, we investigated whether CD4/ZAP-70 compartmentalization could be mediated by an effect of 13B8.2 on the Carma1-Bcl10-MALT1 complex in membrane rafts. We report that treatment of CD3/CD28-activated Jurkat T cells with 13B8.2, but not rituximab, excluded Carma1-Bcl10-MALT1 proteins from GM1(+) membrane rafts and concomitantly decreased NF-κB activation. Fluorescence confocal imaging confirmed that Carma1-Bcl10 and Carma1-MALT1 co-patching, observed in GM1(+) membrane rafts following CD3/CD28 activation, were abrogated after a 24h-treatment with 13B8.2. The CD4/ZAP-70 compartmentalization in membrane rafts induced by 13B8.2 is thus related to Carma1-Bcl10-MALT1 raft exclusion.

Tumor necrosis factor alpha-induced inflammation is increased but apoptosis is inhibited by common food additive carrageenan

Tumor necrosis factor (TNF)-α, a homotrimeric, pleiotropic cytokine, is secreted in response to inflammatory stimuli in diseases such as rheumatoid arthritis and inflammatory bowel disease. TNF-α mediates both apoptosis and inflammation, stimulating an inflammatory cascade through the non-canonical pathway of NF-κB activation, leading to increased nuclear RelB and p52. In contrast, the common food additive carrageenan (CGN) stimulates inflammation through both the canonical and non-canonical pathways of NF-κB activation and utilizes the adaptor molecule BCL10 (B-cell leukemia/lymphoma 10). In a series of experiments, colonic epithelial cells and mouse embryonic fibroblasts were treated with TNF-α and carrageenan in order to simulate the possible effects of exposure to dietary CGN in the setting of a TNF-α-mediated inflammatory disease process. A marked increase in secretion of IL-8 occurred, attributable to synergistic effects on phosphorylated NF-κB-inducing kinase (NIK) in the non-canonical pathway. TNF-α induced the ubiquitination of TRAF2 (TNF receptor-associated factor 2), which interacts with NIK, and CGN induced phosphorylation of BCL10, leading to increased NIK phosphorylation. These results suggest that TNF-α and CGN in combination act to increase NIK phosphorylation, thereby increasing activation of the non-canonical pathway of NF-κB activation. In contrast, the apoptotic effects of TNF-α, including activation of caspase-8 and PARP-1 (poly(ADP-ribose) polymerase 1) fragmentation, were markedly reduced in the presence of CGN, and CGN caused reduced expression of Fas. These findings demonstrate that exposure to CGN drives TNF-α-stimulated cells toward inflammation rather than toward apoptotic cell death and suggest that CGN exposure may compromise the effectiveness of anti-TNF-α therapy.

Lipopolysaccharide-induced activation of NF-κB non-canonical pathway requires BCL10 serine 138 and NIK phosphorylations

BACKGROUND AND AIMS

B-cell lymphoma/leukemia (BCL)-10 and reactive oxygen species mediate two pathways of NF-κB (RelA) activation by lipopolysaccharide (LPS) in human colonic epithelial cells. The pathway for LPS activation of RelB by the non-canonical pathway (RelB) in non-myeloid cells was not yet reported, but important for understanding the range of potential microbial LPS-induced effects in inflammatory bowel disease.

METHODS

Experiments were performed in human colonic epithelial cells and in mouse embryonic fibroblasts deficient in components of the IkappaB kinase (IKK) signalosome, in order to detect mediators of the non-canonical pathway of NF-κB activation, including nuclear RelB and p52 and phospho- and total NF-κB inducing kinase (NIK). BCL10 was silenced by siRNA and effects of mutations of specific phosphorylation sites of BCL10 (Ser138Gly and Ser218Gly) were determined.

RESULTS

By the non-canonical pathway, LPS exposure increased nuclear RelB and p52, and phospho-NIK, with no change in total NIK. Phosphorylation of BCL10 serine 138 was required for NIK phosphorylation, since mutation of this residue eliminated the increases in phospho-NIK and nuclear RelB and p52. Mutations of either serine 138 or serine 218 reduced RelA, p50, and phospho-IκBα of the canonical pathway. Effects of LPS stimulation and BCL10 silencing on NIK phosphorylation were demonstrated in confocal images.

CONCLUSIONS

LPS induces activation of both canonical and non-canonical pathways of NF-κB in human colonic epithelial cells, and the non-canonical pathway requires phosphorylations of BCL10 (serine 138) and NIK. These findings demonstrate the important role of BCL10 in mediating LPS-induced inflammation in human colonic epithelial cells and may open new avenues for therapeutic interventions.

B-cell CLL/lymphoma 10 (BCL10) is required for NF-kappaB production by both canonical and noncanonical pathways and for NF-kappaB-inducing kinase (NIK) phosphorylation

B-cell CLL/lymphoma 10 (BCL10), the caspase recruitment domain (CARD)-containing protein involved in the etiology of the mucosa-associated lymphoid tissue (MALT) lymphomas, has been implicated in inflammatory processes in epithelial cells, as well as in immune cells. Experiments in this report indicate that BCL10 is required for activation of nuclear factor (NF)-kappaB by both canonical and noncanonical pathways, following stimulation by the sulfated polysaccharide carrageenan (CGN). In wild type and IkappaB-kinase (IKK)alpha(-/-) mouse embryonic fibroblasts, increases in phospho-IkappaBalpha, nuclear NF-kappaB p65 (RelA) and p50, and KC, the mouse analog of human interleukin-8, were markedly reduced by silencing BCL10 or by exposure to the free radical scavenger Tempol. In IKKbeta(-/-) cells, BCL10 silencing, but not Tempol, reduced the CGN-induced increases in KC, phospho-NF-kappaB-inducing kinase (NIK), cytoplasmic NF-kappaB p100, and nuclear NF-kappaB p52 and RelB, suggesting a BCL10 requirement for activation of the noncanonical pathway. In NCM460 cells, derived from normal, human colonic epithelium, the CGN-induced increases in NF-kappaB family members, p65, p50, p52, and RelB, were inhibited by BCL10 silencing. Although enzyme-linked immunosorbent assay and confocal images demonstrated no change in total NIK following CGN, increases in phospho-NIK in the wild type, IKKbeta(-/-) and IKKalpha(-/-) cells were inhibited by silencing BCL10. These findings indicate an upstream signaling role for BCL10, in addition to its effects on IKKgamma, the regulatory component of the IKK signalosome, and a requirement for BCL10 in both canonical and noncanonical pathways of NF-kappaB activation. Also, the commonly used food additive carrageenan can be added to the short list of known activators of both pathways.

[High incidence of t (11; 18)/API2-MALT1 and BCL10 aberrant nuclear expression in pulmonary mucosa-associated lymphoid tissue lymphomas]

OBJECTIVE

To detect the BCL10 expression and chromosomal translocations in pulmonary mucosa-associated lymphoid tissue (MALT) lymphomas, including t (11; 18)/API2-MALT1; t (1; 14)/IgH-BCL10 and t (14; 18)/MALT1-IgH, and to determine if aberrant nuclear BCL10 expression is related with chromosomal translocations.

METHODS

Twenty-three cases of pulmonary MALT lymphomas were collected from Cancer Hospital of Fudan University. BCL10 was detected by immunohistochemistry of EnVision method, and API2-MALT1, BCL10, MALT1, IgH chromosomal abnormalities were detected by fluorescent in situ hybridization (FISH) technique.

RESULTS

BCL10 was expressed in 82.6% (19/23) of the pulmonary MALT lymphomas. Among those cases, 9 of 23 (39.1%) were expressed in the cytoplasm, and 10 of 23 (43.5%) were in the nucleus. In the FISH results, 9 cases (39.1%, 9/23) showed API2-MALT1 fusion gene, 1 case with possible BCL10-IgH abnormality, but none showed chromosomal abnormalities related with MALT1 and IgH gene simultaneously. Among 10 BCL10 nuclear expressive cases only 5 harbored genetic abnormalities. There was no correlation between BCL10 aberrant nuclear expression and chromosomal translocations (chi(2) = 0.306, P = 0.685). Follow-up of 10 cases for a period of 7 to 35 months showed that all the patients were alive. Because different treatments applied in different patients (chemotherapy only, surgery with chemotherapy or surgery only), best available treatment could not be confirmed in this study.

CONCLUSIONS

t (11; 18)/API2-MALT1 was the most common chromosomal abnormality in pulmonary MALT lymphomas, but t (1; 14)/BCL10-IgH and t (14; 18)/MALT1-IgH were rare. Pulmonary MALT lymphomas also had higher nuclear BCL10 expression, which was not correlated with chromosomal abnormalities. As a result, BCL10 nuclear expression and cytogenetic aberration may be helpful in the diagnosis, especially for small biopsy specimens.

BCL10 nuclear expression and t(11;18)(q21;q21) indicate nonresponsiveness to Helicobacter pylori eradication of Chinese primary gastric MALT lymphoma

The eradication of Helicobacter pylori (H. pylori) with antibiotics induces complete remission in 75% of patients with gastric MALT lymphoma. We investigated the efficacy of H. pylori eradication and assessed the predictive value of BCL10 nuclear expression and t(11;18)(q21;q21) regarding resistance to H. pylori eradication in primary gastric mucosa-associated lymphoid tissue lymphoma (MALT lymphoma) patients from mainland China. Twenty-two gastric MALT cases (Stage I(E)) underwent H. pylori eradication with antibiotics, and sequential endoscopic-bioptic follow-ups were performed and assessed with regular morphologic and immunohistochemical examinations. BCL10 nuclear expression and interphase fluorescence in situ hybridization (FISH) for MALT1 and API2/MALT1 were tested. Thirteen out of the 22 cases (59.1%) achieved complete regression (CR) after the eradication of H. pylori. The longest follow-up period in the 22 patients was 68 months, with 12 patients longer than 24 months. For the 13 CR patients, the longest follow-up period after H. pylori eradication was 53 months, with 6 patients longer than 24 months. BCL10 nuclear expression was detected by immunohistochemical staining in 9 cases, including 7 (77.8%) of 9 cases who showed no response (NR) and 2 (15.4%) of 13 patients who achieved CR following eradication therapy (P < 0.05). t(11;18)(q21;q21) was evaluated by interphase FISH in 18 cases including 11 CR and 7 NR patients after H. pylori eradication. t(11;18)(q21;q21) was found in 4 (57.1%) of 7 patients who showed NR following H. pylori eradication, but one in 11 CR patients (P < 0.05). A total of 59.1% of patients with early gastric MALT lymphoma recruited in this study achieved CR after H. pylori eradication. BCL10 nuclear expression and t(11;18)(q21;q21)-positive gastric MALT lymphomas are likely to be related to a failure to respond to H. pylori eradication in Chinese patients.

[Abnormal BCL10 nuclear expression and chromosomal translocation in ocular adnexal mucosa-associated lymphoid tissue lymphomas]

OBJECTIVE

To detect the BCL10 expression and several types of chromosomal translocations [including t (11;18)/API2-MALT1; t (1;14)/IgH- BCL10 and t (14;18)/MALT1-IgH] in ocular adnexal mucosa-associated lymphoid tissue lymphomas (OA-MALT lymphomas).

METHODS

Sixty OA-MALT lymphomas were collected from Cancer Hospital of Fudan University. BCL10 was detected by immunohistochemical studies, and API2-MALT1 fusion gene, BCL10, MALT1 and IgH chromosomal abnormalities were detected by fluorescent in situ hybridization (FISH). Fisher's exact test was used to analyze the relation between nuclear BCL10 expression and chromosomal translocation.

RESULTS

BCL10 expressed in 85.0% (51/60) OA-MALT lymphomas. Among these positive cases, 25 cases (41.7%) were expressed in the cytoplasm, and 26 cases (43.3%) were expressed in the nucleus. FISH results showed that no chromosomal abnormalities related with BCL10 and IgH genes, except 2 cases with API2-MALT1 fusion gene. Under statistic of Fisher exact test, nuclear BCL10 expression and API2-MALT1 fusion gene were two independent factors (P > 0.05).

CONCLUSIONS

BCL10 nuclear expression is common in OA-MALT lymphomas and may be used as a potential marker for the diagnosis of MALT lymphomas arising from ocular adnexa. Aberrant chromosomal translocations reported in the other sites MALT lymphomas are rare in OA-MALT lymphomas.

Toll-like receptor 4 mediates induction of the Bcl10-NFkappaB-interleukin-8 inflammatory pathway by carrageenan in human intestinal epithelial cells

The sulfated polysaccharide carrageenan (CGN) induces activation of NFkappaB and interleukin 8 (IL-8) in human colonic epithelial cells through a pathway of innate immunity mediated by Bcl10 (B-cell CLL/lymphoma 10). In this report, we identify Toll-like receptor 4 (TLR4), a member of the family of innate immune receptors, as the surface membrane receptor for CGN in human colonic epithelial cells. Experiments with fluorescence-tagged CGN demonstrated a marked reduction in binding of CGN to human intestinal epithelial cells and to RAW 264.7 mouse macrophages, following exposure to TLR4 blocking antibody (HTA-125). Binding of CGN to 10ScNCr/23 mouse macrophages, which are deficient in the genetic locus for TLR4, was absent. Additional experiments with TLR4 blocking antibody and TLR4 small interfering RNAs showed 80% reductions in CGN-induced increases in Bcl10 and IL-8. Transfection with dominant-negative MyD88 plasmid demonstrated MyD88 dependence of the CGN-TLR4-triggered increases in Bcl10 and IL-8. Therefore, these results indicate that CGN-induced inflammation in human colonocytes proceeds through a pathway of innate immunity, perhaps related to the unusual alpha-1,3-galactosidic linkage characteristic of CGN, and suggest how dietary CGN intake may contribute to human intestinal inflammation. Because CGN is a commonly used food additive in the Western diet, clarification of its effects and mechanisms of action are vital to issues of food safety.

Higher rates of t(11;18) in Chinese patients with transformed type of MALT lymphoma suggest novel pathways for progression of the disease

To detect the t(11;18) chromosome translocation in different stages of mucosa-associated lymphoid tissue (MALT) lymphoma, we established a RT-PCR method by adopting three new primer pairs and using the RNA extracted from the paraffin tissues to amplify the t(11;18) fusion gene API2-MALT1 in shorter lengths. Our results showed five key findings, which are (a) higher detection rates of t(11;18) (21.13%) in Chinese patients with transformed MALT lymphoma, (b) lower detection rates of t(11;18) in stomach MALT lymphoma, (c) different organ localizations of MALT lymphoma in Chinese patients, (d) higher nuclear expression rates of Bcl-10 in low grade MALT (51.72%), and (e) lower response rates (50% CR, and 50% PR) to anti-H.-pylori therapy. These findings suggest novel pathways for low-grade MALT lymphoma to be progressed into transformed MALT lymphoma. This study also suggests that amplification of shorter length of PCR products from the paraffin-fixed tissues increases sensitivity, which is significant in improving the selection of the therapeutic regimen and assessing the prognosis of the disease.

Ubiquitination for activation: new directions in the NF-kappaB roadmap

Signal transduction through the T cell receptor (TCR) and a costimulatory molecule, CD28, results in the stimulation of multiple signaling pathways, leading to the activation of several transcription factors including activator protein-1 (AP-1), nuclear factor of activated T cells (NF-AT), and nuclear factor kappa B (NF-kappaB). The molecular mechanisms by which NF-kappaB is activated by TCR-CD28 have only recently become known. New findings indicate that the adaptor molecules CARMA1 and Bcl10 are essential to the process. Additionally, a critical role for MALT1/paracaspase has been identified. MALT1, CARMA1, and Bcl10 form a tripartite protein complex, in which Bcl10 is thought to facilitate the oligomerization of MALT1 monomers. Overexpression of MALT1, as observed in a subset of lymphoma patients, leads to the potent activation of NF-kappaB, suggesting that MALT1 might stimulate (directly or indirectly) the kinase complex [IKK, inhibitor of NF-kappaB (IkappaB) kinase] responsible for activating cytoplasmic NF-kappaB for translocation into the nucleus. Moreover, the MALT1-CARMA1-Bcl10 complex is responsible for ubiquitination of NEMO, a step that appears to be critical for TCR-induced NF-kappaB activation but not for induction mediated by other stimuli such as TNF or IL-1.

Erythropoietin treatment of human ovarian cancer cells results in enhanced signaling and a paclitaxel-resistant phenotype

Erythropoietin (Epo), a glycoprotein hormone that is the principal regulator of erythropoiesis, is known to act also on nonhematopoietic cell types. Epo receptors have been reported on several normal and neoplastic human cells and tissues, including ovarian cancer cells. We found that long-term Epo treatment of A2780 cells resulted in the development of a phenotype exhibiting both enhanced Epo signaling, evidenced by increased peak levels of phospho-Erk1/2 and increased paclitaxel resistance. This phenotypic effect was specific for paclitaxel, since no change in cisplatin or carboplatin sensitivity was observed. In addition, the change in phenotype was stable, even after the removal of Epo. Measurement of mono- and oligonucleosome formation revealed that long-term Epo treated A2780 cells exhibited markedly less apoptosis than nonerythropoietin treated cells at essentially all concentrations of paclitaxel tested. Western blot analyses revealed that the long-term Epo treated cells had significantly reduced expression of apoptosis-related proteins Bcl-2 and Bcl-10. These findings may have implications for the clinical use of recombinant human Epo and other erythropoiesis stimulating agents to correct anemia in paclitaxel-treated cancer patients.

[Abnormal expression of bcl-10 protein in extranodal marginal zone B cell lymphoma of mucosa-associated lymphoid tissue lymphoma type]

OBJECTIVE

To evaluate the diagnostic role of nuclear expression of bcl-10 protein in extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) type.

METHODS

One hundred and forty cases of MALT lymphoma were collected from Cancer Hospital of Fudan University (including 38 cases from stomach, 35 cases from ocular adnexa, 16 cases from intestine, 15 cases from skin, 15 cases from salivary gland, 14 cases from lung, 3 cases from thyroid and 4 cases from other sites). Ten cases of reactive follicular hyperplasia of tonsil, 5 cases of reactive lymphoid hyperplasia of orbit and 143 cases of non-Hodgkin's lymphoma other than MALT lymphoma (including 20 cases of NK/T cell lymphoma, 20 cases of follicular lymphomas, 20 cases of anaplastic large cell lymphomas, 20 cases of nodal diffuse large cell B-cell lymphoma (DLBCL), 10 cases of gastric diffuse large B-cell lymphoma, 13 cases of nodal marginal zone B-cell lymphoma, 12 cases of mantle cell lymphoma, 11 cases of splenic marginal zone B-cell lymphoma, 6 cases of angioimmunoblastic T-cell lymphoma, 6 cases of peripheral T-cell lymphoma, not otherwise specified, 3 cases of small lymphocytic lymphoma, 1 case of lymphoplasmacytic lymphoma and 1 case of plasmacytoma were used as controls. Immunohistochemical study for bcl-10, as well as dual staining with CD20, was performed by EnVision method in paraffin sections.

RESULTS

In reactive follicular hyperplasia of tonsil, bcl-10 was moderately or strongly expressed in the cytoplasm of germinal center B cells, while the mantle cells were negative and the marginal zone cells and paracortical T cells showed weak staining. In the 5 cases of reactive lymphoid hyperplasia of orbit, 2 were bcl-10-negative and the remaining 3 expressed bcl-10 in the cytoplasm of germinal center B cells. As for non-MALT lymphomas, 3 gastric DLBCL showed nuclear expression. The remaining cases showed variable cytoplasmic staining. In some cases of lymphoma, bcl-10 was expressed in tumor cells but not in reactive lymphoid cells. On the other hand, 92.1% (129/140) of MALT lymphoma were bcl-10 positive. Among those cases, 54.3% (76/140) showed cytoplasmic positivity and 37.9% (53/140) showed nuclear positivity. The nuclear positivity rate of bcl-10 in different anatomic sites was different. The staining was most intense in MALT lymphoma of ocular adnexa. Dual staining with CD20 showed that the bcl-10-positive cells were also CD20-positive, though the number of bcl-10-positive cells were less than that of CD20-positive cells.

CONCLUSIONS

Bcl-10 expression in lymphoid hyperplasia is a universal phenomenon. Cytoplasmic expression of bcl-10 is seen in many different kinds of non-Hodgkin's lymphoma and reactive lymphoid conditions. In some cases of lymphoma, bcl-10 is expressed in tumor cells but not in reactive lymphoid cells, suggesting a possible role of abnormal bcl-10 expression in tumorgenesis. Nuclear expression of bcl-10 is seen mainly in MALT lymphoma, especially when occurring in ocular adnexa and lung. This is in contrast to loss of bcl-10 expression in residual germinal center cells.

Bcl10 plays a divergent role in NK cell-mediated cytotoxicity and cytokine generation

Activating receptors such as NKG2D and Ly49D mediate a multitude of effector functions including cytotoxicity and cytokine generation in NK cells. However, specific signaling events that are responsible for the divergence of distinct effector functions have yet to be determined. In this study, we show that lack of caspase recruitment domain-containing protein Bcl10 significantly affected receptor-mediated cytokine and chemokine generation, but not cytotoxicity against tumor cells representing "missing-self" or "induced-self." Lack of Bcl10 completely abrogated the generation of GM-CSF and chemokines and it significantly reduced the generation of IFN-gamma (>75%) in NK cells. Commitment, development, and terminal maturation of NK cells were largely unaffected in the absence of Bcl10. Although IL-2-activated NK cells could mediate cytotoxicity to the full extent, the ability of the freshly isolated NK cells to mediate cytotoxicity was somewhat reduced. Therefore, we conclude that the Carma1-Bcl10-Malt1 signaling axis is critical for cytokine and chemokine generation, although it is dispensable for cytotoxic granule release depending on the activation state of NK cells. These results indicate that Bcl10 represents an exclusive "molecular switch" that links the upstream receptor-mediated signaling to cytokine and chemokine generations.

[Clonal relationship between transformed and non-transformed components in mucosa-associated lymphoid tissue lymphoma]

OBJECTIVE

To analyze the clonal relationship between transformed and non-transformed components in mucosa-associated lymphoid tissue (MALT) lymphoma.

METHODS

Six cases of MALT lymphoma with high-grade transformation were studied. Immunohistochemical study was carried out by EliVision using bcl-10 antibody. Reverse transcription-polymerase chain reaction was used to detect the presence of API2-MALT1 fusion gene transcripts. The target cells were selected by laser microdissection and studied by polymerase chain reaction and sequence analysis for rearrangement of immunoglobulin heavy chain gene.

RESULTS

In the 6 cases of MALT lymphoma with high-grade transformation, nuclear and cytoplasmic expression of bcl-10 was demonstrated in 1 case, while API2-MALT1 fusion gene was present in 2 cases. Identical fragments of rearranged immunoglobulin heavy chain gene were detected in both transformed and non-transformed components in each of the 6 cases, except for the differences at 2 nucleotide positions in N or D regions in 2 cases.

CONCLUSION

The tumor cells from both transformed and non-transformed components in MALT lymphoma derive from the same clone.

[Significance of detection of Bcl-10 novel mutation in ocular adnexal mucosa-associated lymphoid tissue lymphoma]

OBJECTIVE

To examine the expression of Bc1-10 gene in mucosa-associated lymphoid tissue (MALT) lymphomas, atypical lymphatic hyperplasia and reactive lymphatic hyperplasia; as well as to discover novel mutations and their role in clinical diagnosis and pathogenesis of ocular adnexal lymphatic disorders.

METHODS

Thirty-one specimens of ocular adnexal lymphoma were obtained from the department of ophthalmology of Shanghai Changzheng hospital, second military medical university during surgery and were preserved in liquid nitrogen immediately after harvesting. The expression of Bc1-10 gene in ocular adnexal specimens was examined by molecular biological methods. The DNA sequences were analyzed by Sanger method and the results were compared with those of the Gene Bank blast to identify novel mutations. The protein expression of mutant Bc1-10 and NF-kappaB in these specimens were detected by immunohistological method and immunofluorescence. Confocal microscope was used to observe the colocalization of Bc1-10 and NF-kappaB expressions.

RESULTS

Of the 31 specimens, 14 were positive for Bc1-10, of which 10 showed novel mutations of Bc1-10. One of the four atypical lymphatic hyperplasia specimens was positive for Bc1-10, this mutation was reported by others previously. One of the four reactive lymphatic hyperplasia specimens was positive for Bc1-10. Fourteen (60.8%) of the 23 MALT lymphoma specimens were positive for aberration of Bc1-10, including 6 cases with nuclear expression at moderate intensity and 8 cases with expression in the cytoplasm at weak to moderate intensities. Mutations of Bcl-10 were also expressed in the cytoplasm at moderate intensity in two cases with atypical lymphatic hyperplasia and expressed at moderate intensity in one case with reactive lymphatic hyperplasia. I kappa alpha was expressed diffusely in the cytoplasm in 20 cases, among which co-expression of I kappa alpha and Bcl-10 was present in 14 cases.

CONCLUSIONS

Novel mutation of Bc1-10 gene in ocular adnexal MALT lymphoma is detected in Chinese patients. Detection of genetic mutation is consistent with and more sensitive than the pathological diagnosis. It can be used to identify the stage and the quality of the disease even no morphological changes are present for discrimination. It can be used as a sensitive index for early diagnosis.

Development, evaluation, and application of a highly sensitive microtiter plate ELISA for human Bcl10 protein

Bcl10 (B-cell CLL/lymphoma 10) is a 233 amino acid CARD (caspase recruitment domain)-containing cellular protein, increasingly recognized as a mediator of NFkappaB activation in non-immune, as well as immune cells. Due to the importance of Bcl10 in diverse cell types, we developed a solid-phase, enzyme-linked immunosorbent (ELISA) assay to precisely measure Bcl10 in small volume cell lysates, using recombinant Bcl10 to standardize the assay. Standard curve measures Bcl10 from 0.25 ng/mL to 16 ng/mL, with very low intra- and inter-assay variation. Sample dilution and exogenous Bcl10 recovery experiments, comparisons with Western blot, and linear response to increasing doses of known Bcl10 activators confirm the specificity and precision of the ELISA.

Bcl10 mediates LPS-induced activation of NF-kappaB and IL-8 in human intestinal epithelial cells

Lipopolysaccharide (LPS) is recognized as an inducer of the inflammatory response associated with gram-negative sepsis and systemic inflammatory response syndrome. LPS induction proceeds through Toll-like receptor (TLR) in immune cells and intestinal epithelial cells (IEC). This report presents the first identification of Bcl10 (B-cell CLL/lymphoma 10) as a mediator of the LPS-induced activation of IL-8 in human IEC. Bcl10 is a caspase-recruitment domain-containing protein, associated with constitutive activation of NF-kappaB in MALT (mucosa-associated lymphoid tissue) lymphomas. The normal human IEC line NCM460, normal primary human colonocytes, and ex vivo human colonic tissue were exposed to 10 ng/ml of LPS for 2-6 h. Effects on Bcl10, phospho-IkappaBalpha, NF-kappaB, and IL-8 were determined by Western blot, ELISA, immunohistochemistry, and confocal microscopy. Effects of Bcl10 silencing by small-interfering RNA (siRNA), TLR4 blocking antibody, TLR4 silencing by siRNA, and an IL-1 receptor-associated kinase (IRAK)-1/4 inhibitor on LPS-induced activation were examined. Following Bcl10 silencing, LPS-induced increases in NF-kappaB, IkappaBalpha, and IL-8 were significantly reduced (P < 0.001). Increasing concentrations of LPS were associated with higher concentrations of Bcl10 protein when quantified by ELISA, and the association between LPS exposure and increased Bcl10 was also demonstrated by Western blot, immunohistochemistry, and confocal microscopy. Exposure to TLR4 antibody, TLR4 siRNA, or an IRAK-1/4 inhibitor eliminated the LPS-induced increases in Bcl10, NF-kappaB, and IL-8. Identification of Bcl10 as a mediator of LPS-induced activation of NF-kappaB and IL-8 in normal human IEC provides new insight into mechanisms of epithelial inflammation and new opportunities for therapeutic intervention.

MALT1 directs B cell receptor-induced canonical nuclear factor-kappaB signaling selectively to the c-Rel subunit

NF-kappaB (Rel) transcription factors control physiological and pathological immune cell function. The scaffold proteins Bcl-10 and MALT1 couple antigen-receptor signals to the canonical NF-kappaB pathway and are pivotal in lymphomagenesis. Here we found that Bcl-10 and MALT1 differentially regulated B cell receptor-induced activation of RelA and c-Rel. Bcl-10 was essential for recruitment of the kinase IKK into lipid rafts for the activation of RelA and c-Rel, for blocking apoptosis and for inducing division after B cell receptor ligation. In contrast, MALT1 participated in survival signaling but was not involved in IKK recruitment or activation and was dispensable for RelA induction and proliferation. MALT1 selectively activated c-Rel to control a distinct subprogram. Our results provide mechanistic insights into B cell receptor-induced survival and proliferation signals and demonstrate the selective control of c-Rel in the canonical NF-kappaB pathway.

Bcl10 controls TCR- and FcgammaR-induced actin polymerization

Bcl10 plays an essential role in the adaptive immune response, because Bcl10-deficient lymphocytes show impaired Ag receptor-induced NF-kappaB activation and cytokine production. Bcl10 is a phosphoprotein, but the physiological relevance of this posttranslational modification remains poorly defined. In this study, we report that Bcl10 is rapidly phosphorylated upon activation of human T cells by PMA/ionomycin- or anti-CD3 treatment, and identify Ser(138) as a key residue necessary for Bcl10 phosphorylation. We also show that a phosphorylation-deficient Ser(138)/Ala mutant specifically inhibits TCR-induced actin polymerization yet does not affect NF-kappaB activation. Moreover, silencing of Bcl10, but not of caspase recruitment domain-containing MAGUK protein-1 (Carma1) induces a clear defect in TCR-induced F-actin formation, cell spreading, and conjugate formation. Remarkably, Bcl10 silencing also impairs FcgammaR-induced actin polymerization and phagocytosis in human monocytes. These results point to a key role of Bcl10 in F-actin-dependent immune responses of T cells and monocytes/macrophages.

Post-translational modifications regulate distinct functions of CARMA1 and BCL10

Activation of the transcription factor nuclear factor (NF)-kappaB is essential for the normal functioning of the immune system. Deregulated NF-kappaB signalling in lymphocytes can lead to immunodeficiency, but also to autoimmunity or lymphomas. Many of the signalling components controlling NF-kappaB activation in lymphocytes are now known, but it is less clear how distinct molecular components of this pathway are regulated. Here, we summarize recent findings on post-translational modifications of intracellular components of this pathway. Phosphorylation of the CARMA1 and BCL10 proteins and ubiquitylation of BCL10 affect the formation and stability of the CARMA1-BCL10-MALT1 (CBM) complex, and also control negative feedback regulation of the NF-kappaB signalling pathway. Moreover, the study of BCL10 phosphorylation isoforms has revealed a new mechanism controlling BCL10 nuclear translocation and an unexpected role for BCL10 in the regulation of the actin cytoskeleton.

Regulation of NF-kappaB activation in T cells via association of the adapter proteins ADAP and CARMA1

The adapter protein ADAP regulates T lymphocyte adhesion and activation. We present evidence for a previously unrecognized function for ADAP in regulating T cell receptor (TCR)-mediated activation of the transcription factor NF-kappaB. Stimulation of ADAP-deficient mouse T cells with antibodies to CD3 and CD28 resulted in impaired nuclear translocation of NF-kappaB, a reduced DNA binding, and delayed degradation and decreased phosphorylation of IkappaB (inhibitor of NF-kappaB). TCR-stimulated assembly of the CARMA1-BCL-10-MALT1 complex was substantially impaired in the absence of ADAP. We further identified a region of ADAP that is required for association with the CARMA1 adapter and NF-kappaB activation but is not required for ADAP-dependent regulation of adhesion. These findings provide new insights into ADAP function and the mechanism by which CARMA1 regulates NF-kappaB activation in T cells.

Phosphorylation of Bcl10 negatively regulates T-cell receptor-mediated NF-kappaB activation

Bcl10 (B-cell lymphoma 10) is an adaptor protein comprised of an N-terminal caspase recruitment domain and a C-terminal serine/threonine-rich domain. Bcl10 plays a critical role in antigen receptor-mediated NF-kappaB activation and lymphocyte development and functions. Our current study has discovered that T-cell activation induced monophosphorylation and biphosphorylation of Bcl10 and has identified S138 within Bcl10 as one of the T-cell receptor-induced phosphorylation sites. Alteration of S138 to an alanine residue impaired T-cell activation-induced ubiquitination and subsequent degradation of Bcl10, ultimately resulting in prolongation of TCR-mediated NF-kappaB activation and enhancement of interleukin-2 production. Taken together, our findings demonstrate that phosphorylation of Bcl10 at S138 down-regulates Bcl10 protein levels and thus negatively regulates T-cell receptor-mediated NF-kappaB activation.

CARD-Bcl10-Malt1 signalosomes: missing link to NF-kappaB

CARD11 (CARMA1), Bcl10, and Malt1 are required for nuclear factor NF-kappaB activation in response to antigen recognition. Initially, gene disruption experiments in mice pointed to a lymphocyte-specific role for CARD11-Bcl10-Malt1 complexes. However, strong evidence suggesting that conserved Bcl10-Malt1 complexes interact with different CARD scaffolds to connect various receptors in different cell types to NF-kappaB signaling has emerged more recently. The CARD10 (CARMA3)-Bcl10-Malt1 signalosome functions as a link between G protein-coupled receptor (GPCR) signaling and proinflammatory NF-kappaB activation. Further, Dectin-1-induced antifungal responses to NF-kappaB in dendritic cells depend on CARD9-Bcl10-Malt1. These results identify CARD-Bcl10-Malt1 signalosomes as pivotal regulators that link not only innate and adaptive immune responses, but also GPCR signaling, to the canonical NF-kappaB pathway.

Caspase-8 and c-FLIPL associate in lipid rafts with NF-kappaB adaptors during T cell activation

Humans and mice lacking functional caspase-8 in T cells manifest a profound immunodeficiency syndrome due to defective T cell antigen receptor (TCR)-induced NF-kappaB signaling and proliferation. It is unknown how caspase-8 is activated following T cell stimulation, and what is the caspase-8 substrate(s) that is necessary to initiate T cell cycling. We observe that following TCR ligation, a small portion of total cellular caspase-8 and c-FLIP(L) rapidly migrate to lipid rafts where they associate in an active caspase complex. Activation of caspase-8 in lipid rafts is followed by rapid cleavage of c-FLIP(L) at a known caspase-8 cleavage site. The active caspase.c-FLIP complex forms in the absence of Fas (CD95/APO1) and associates with the NF-kappaB signaling molecules RIP1, TRAF2, and TRAF6, as well as upstream NF-kappaB regulators PKC theta, CARMA1, Bcl-10, and MALT1, which connect to the TCR. The lack of caspase-8 results in the absence of MALT1 and Bcl-10 in the active caspase complex. Consistent with this observation, inhibition of caspase activity attenuates NF-kappaB activation. The current findings define a link among TCR, caspases, and the NF-kappaB pathway that occurs in a sequestered lipid raft environment in T cells.

Transcriptional profiling of the nuclear factor-kappaB pathway identifies a subgroup of primary lymphoma of the central nervous system with low BCL10 expression

Recent studies point to a role of nuclear factor (NF)-kappaB signaling in a subset of diffuse large B cell lymphomas. We have analyzed the expression of 21 genes encoding NF-kappaB family members, upstream modulators, and targets in 32 primary central nervous system lymphomas (PCNSLs) by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR). Compared with nonmalignant germinal center centroblasts, expression of BCL10, REL, IAP1, and TRAF1 was significantly lower in PCNSLs, whereas that of BAX, BCLXL, BCL2, MALT1, CARD9, CARD10, CARD11, CARD14, CCND2, cFLIP, RELA, RELB, NFKB1, NFKB2, and IRF4 was higher. Hierarchical clustering of gene expression data revealed two distinct subgroups of PCNSLs, which were characterized by significantly different transcriptional levels, predominantly of BCL10, but also of REL and IAP1. Thus, these quantitative RT-PCR data with expression of genes of the NF-kappaB family as well as NF-kappaB-regulated genes together with immunohistochemical detection of nuclear RELA and REL indicate activation of the NF-kappaB pathway in PCNSLs, which may contribute to their high proliferative activity and the low level of apoptosis.

CARMA3 deficiency abrogates G protein-coupled receptor-induced NF-{kappa}B activation

G protein-coupled receptors (GPCRs) play pivotal roles in regulating various cellular functions. Although many GPCRs induce NF-kappaB activation, the molecular mechanism of GPCR-induced NF-kappaB activation remains largely unknown. CARMA3 (CARD and MAGUK domain-containing protein 3) is a scaffold molecule with unknown biological functions. By generating CARMA3 knockout mice using the gene targeting approach, here we show CARMA3 is required for GPCR-induced NF-kappaB activation. Mechanistically, we found that CARMA3 deficiency impairs GPCR-induced IkappaB kinase (IKK) activation, although it does not affect GPCR-induced IKKalpha/beta phosphorylation, indicating that inducible phosphorylation of IKKalpha/beta alone is not sufficient to induce its kinase activity. We also found that CARMA3 is physically associated with NEMO/IKKgamma, and induces polyubiquitination of an unknown protein(s) that associates with NEMO, likely by linking NEMO to TRAF6. Consistently, we found TRAF6 deficiency also abrogates GPCR-induced NF-kappaB activation. Together, our results provide the genetic evidence that CARMA3 is required for GPCR-induced NF-kappaB activation.