Cooperative Control of Caspase Recruitment Domain-containing Protein 11 (CARD11) Signaling by an Unusual Array of Redundant Repressive Elements

Recent advancements in the diverse roles of polymerase-associated proteins in the replication and pathogenesis of Newcastle disease virus

Newcastle disease virus (NDV) is a significant member of the Paramyxoviridae family, known for causing epidemics and substantial economic losses in the poultry industry worldwide. The NDV RNA genome primarily encodes six structural proteins (N, P, M, F, HN, and L) and two non-structural proteins (V and W). Among these, the polymerase-associated proteins (N, P, and L) and the viral RNA (vRNA) genome form the ribonucleoprotein complex, which plays a crucial role in the synthesis and transcription of NDV vRNA. In the last two decades, numerous studies have demonstrated that the polymerase-associated proteins are linked to the virulence, pathotype, and thermostability of NDV. Additionally, the interactions between these polymerase-associated proteins and host proteins are closely related to the NDV's replication and pathogenicity. Despite significant progress in understanding the unique and shared functions of NDV polymerase-associated proteins, research on these viral proteins' structure and function is less comprehensive than other NDV proteins, and the available information is often scattered. Therefore, this article systematically summarises and reviews the research progress made in understanding the structural features, virulence, pathotype, and thermostability correlation of NDV polymerase-associated proteins, as well as the critical roles of interactions between polymerase-associated proteins and host proteins in NDV replication and pathogenicity. This review aims to enhance our understanding of the complex functions of polymerase-associated proteins in NDV replication and pathogenesis and to contribute to the development of more effective vaccines and antiviral drugs against NDV challenges.

Novel homozygous CARD11 variants in two patients with combined immunodeficiency and atopic skin disease

Background

Caspase recruitment domain family, member 11 (CARD11) is an important protein which plays a fundamental role in the activation of NF-κβ pathway in lymphocytes. CARD11 deficiency can be inherited in either autosomal dominant or autosomal recessive forms and present with different phenotypes including combined immunodeficiency, atopic dermatitis, and other variable manifestations. The present report describes clinical phenotypes and immunological defects of two unrelated patients with missense homozygous variants in CARD11 presenting with combined immunodeficiency (CID) and atopic skin disease resembling that reported in dominant negative CARD11 deficiency. The patients underwent next generation sequencing, immunophenotyping of T and B subsets by flow cytometry, T cell stimulation, and evaluation of CARD11 expression.

Results

Both patients had features suggesting CID including repeated pneumoniae with ICU admissions, chronic diarrhea, and itchy atopic skin disease. Patient-1 has homozygous missense variant in the C terminal domain (c.2839G > A, p.Glu947Lys), and patient-2 has homozygous variant in the inhibitory domain (c.1073C > G, p.Pro568Arg). Both have profound defects in Tregs with normal recent thymic emigrants, memory, and naïve CD4+ T cells. However, in response to stimulation, T cells failed to upregulate the expression of CD25. CARD11 expression by flow cytometry was decreased rather than abolished as previously described in patients with autosomal recessive CARD11 deficiency. B cells showed marked deficiency of switched memory and increase in transitional B cells.

Conclusion

Missense variants causing CARD11 deficiency may affect the protein function rather than the expression and can result in a phenotype combining the atopic skin disease and the features of CID.

KLF5‑mediated expression of CARD11 promotes the progression of gastric cancer

Caspase recruitment domain-containing protein 11 (CARD11) has been reported as functioning in multiple types of cancers. In the present study, the role and mechanism of CARD11 in gastric cancer was investigated. First, CARD11 expression in gastric cancer tissues and the association of CARD11 with overall survival were analyzed by the encyclopedia of RNA interactomes database. CARD11 expression in gastric cancer cells was detected by western blotting and reverse transcription-quantitative PCR analyses. After CARD11 silencing, cell proliferation was evaluated by Cell Counting Kit-8 assay, 5-ethynyl-2'-deoxyuridine staining and flow cytometry analysis. Wound healing and Transwell assays were used to measure the capacities of cell migration and invasion. Additionally, the expression levels of epithelial-mesenchymal transition (EMT)-related proteins and mTOR-related proteins were detected by western blot analysis. HumanTFDB predicted the binding of the transcription factor Krüppel-like factor 5 (KLF5) to the CARD11 promoter, which was confirmed by dual luciferase reporter and chromatin immunoprecipitation assays. To explore the regulatory effects between KLF5 and CARD11, KLF5 was overexpressed to perform the rescue experiments in gastric cancer cells with CARD11 silencing. Results revealed that CARD11 was highly expressed in gastric cancer and was associated with poor prognosis. CARD11 interference inhibited the proliferation of gastric cancer cells and induced cell cycle arrest. Additionally, CARD11 silencing suppressed the migration, invasion and EMT of gastric cancer cells, accompanied by upregulated E-cadherin expression and downregulated N-cadherin and vimentin expression. Moreover, the transcription factor KLF5 positively regulated the transcription of CARD11 in gastric cancer. KLF5 overexpression reversed the effects of interference of CARD11 expression in gastric cancer cells to promote their proliferation, migration, invasion and EMT. KLF5 overexpression also led to a reduction in cell cycle arrest. Finally, interference of CARD11 expression suppressed the mTOR pathway, which was activated by KLF5. In conclusion, KLF5-mediated CARD11 promoted the proliferation, migration and invasion of gastric cancer cells.

CARD11 gain-of-function mutation drives cell-autonomous accumulation of PD-1+ ICOShigh activated T cells, T-follicular, T-regulatory and T-follicular regulatory cells

Introduction

Germline CARD11 gain-of-function (GOF) mutations cause B cell Expansion with NF-κB and T cell Anergy (BENTA) disease, whilst somatic GOF CARD11 mutations recur in diffuse large B cell lymphoma (DLBCL) and in up to 30% of the peripheral T cell lymphomas (PTCL) adult T cell leukemia/lymphoma (ATL), cutaneous T cell lymphoma (CTCL) and Sezary Syndrome. Despite their frequent acquisition by PTCL, the T cell-intrinsic effects of CARD11 GOF mutations are poorly understood.

Methods

Here, we studied B and T lymphocytes in mice with a germline Nethyl-N-nitrosourea (ENU)-induced Card11^M365K mutation identical to a mutation identified in DLBCL and modifying a conserved region of the CARD11 coiled-coil domain recurrently mutated in DLBCL and PTCL.

Results and discussion

Our results demonstrate that CARD11.M365K is a GOF protein that increases B and T lymphocyte activation and proliferation following antigen receptor stimulation. Germline Card11^M365K mutation was insufficient alone to cause B or T-lymphoma, but increased accumulation of germinal center (GC) B cells in unimmunized and immunized mice. Card11^M365K mutation caused cell-intrinsic over-accumulation of activated T cells, T regulatory (T_REG), T follicular (T_FH) and T follicular regulatory (T_FR) cells expressing increased levels of ICOS, CTLA-4 and PD-1 checkpoint molecules. Our results reveal CARD11 as an important, cell-autonomous positive regulator of T_FH, T_REG and T_FR cells. They highlight T cell-intrinsic effects of a GOF mutation in the CARD11 gene, which is recurrently mutated in T cell malignancies that are often aggressive and associated with variable clinical outcomes.

Elevated IgE from attenuated CARD11 signaling: lessons from atopic mice and humans

CARD11 encodes a large scaffold protein responsible for integrating antigen-receptor engagement with downstream signaling to NF-kB and other outputs in lymphocytes. Over the past 10 years, several human-inborn errors of immunity have been linked to pathogenic CARD11 mutations. Most recently, severe atopic patients were discovered that carried heterozygous dominant-negative CARD11 mutations. Here, we review the mechanistic connections between attenuated CARD11 signaling, elevated IgE, and atopy, comparing and contrasting key insights from both human patients and murine models. Continued investigation of abnormal CARD11 signaling in both contexts should inform novel therapeutic strategies to combat allergic pathogenesis.

Phosphorylation of serine-893 in CARD11 suppresses the formation and activity of the CARD11-BCL10-MALT1 complex in T and B cells

CARD11 acts as a gatekeeper for adaptive immune responses after T cell or B cell antigen receptor (TCR/BCR) ligation on lymphocytes. PKCθ/β-catalyzed phosphorylation of CARD11 promotes the assembly of the CARD11-BCL10-MALT1 (CBM) complex and lymphocyte activation. Here, we demonstrated that PKCθ/β-dependent CARD11 phosphorylation also suppressed CARD11 functions in T or B cells. Through mass spectrometry-based proteomics analysis, we identified multiple constitutive and inducible CARD11 phosphorylation sites in T cells. We demonstrated that a single TCR- or BCR-inducible phosphorylation on Ser⁸⁹³ in the carboxyl terminus of CARD11 prevented the activation of the transcription factor NF-κB, the kinase JNK, and the protease MALT1. Moreover, CARD11 Ser⁸⁹³ phosphorylation sensitized BCR-addicted lymphoma cells to toxicity induced by Bruton's tyrosine kinase (BTK) inhibitors. Phosphorylation of Ser⁸⁹³ in CARD11 by PKCθ controlled the strength of CARD11 scaffolding by impairing the formation of the CBM complex. Thus, PKCθ simultaneously catalyzes both stimulatory and inhibitory CARD11 phosphorylation events, which shape the strength of CARD11 signaling in lymphocytes.

Mechanistic impact of oligomer poisoning by dominant-negative CARD11 variants

The CARD11 scaffold controls antigen receptor signaling to NF-κB, JNK, and mTOR. Three classes of germline mutations in CARD11 cause Primary Immunodeficiency, including homozygous loss-of-function (LOF) mutations in CARD11 deficiency, heterozygous gain-of-function (GOF) mutations in BENTA disease, and heterozygous dominant-negative LOF mutations in CADINS. Here, we characterize LOF CARD11 mutants with a range of dominant-negative activities to identify the mechanistic properties that cause these variants to exert dominant effects when heterozygous. We find that strong dominant negatives can poison signaling from mixed wild-type:mutant oligomers at two steps in the CARD11 signaling cycle, at the Opening Step and at the Cofactor Association Step. Our findings provide evidence that CARD11 oligomer subunits cooperate in at least two steps during antigen receptor signaling and reveal how different LOF mutations in the same oligomeric signaling hub may cause disease with different inheritance patterns.

CARD11 is a novel target of miR-181b that is upregulated in chronic lymphocytic leukemia

Aim: To investigate the targets of miR-181b in patients with chronic lymphocytic leukemia (CLL). Materials & methods: The bioinformatic softwares were used to indicate the key target genes associated with miR-181b, and the results were verified in CLL patient samples and 293T cells. Results: CARD11 is a potential target gene of miR-181b, an inverse relationship was revealed between the expression of CARD11 and miR-181b in 104 CLL patients, and it was confirmed in vitro with luciferase assays and western blotting. Kaplan-Meier analysis showed that CLL patients with high CARD11 expression demonstrated poor survival. Conclusion: CARD11 is a novel target of miR-181b that is upregulated, which could be a poor prognostic indicator for CLL patients.

Bcl10 is required for the development and suppressive function of Foxp3+ regulatory T cells

Foxp3+ regulatory T (Treg) cells play a critical role in peripheral tolerance. Bcl10, acting as a scaffolding protein in the Carma1-Bcl10-Malt1 (CBM) complex, has a critical role in TCR-induced signaling, leading to NF-κB activation and is required for T-cell activation. The role of Bcl10 in conventional T (Tconv) cells has been well characterized; however, the role of Bcl10 in the development of Treg cells and the maintenance of the suppressive function and identity of these cells has not been well characterized. In this study, we found that Bcl10 was required for not only the development but also the function of Treg cells. After deleting Bcl10 in T cells, we found that the development of Treg cells was significantly impaired. When Bcl10 was specifically deleted in mature Treg cells, the suppressive function of the Treg cells was impaired, leading to lethal autoimmunity in Bcl10fl/flFoxp3cre mice. Consistently, in contrast to WT Treg cells, Bcl10-deficient Treg cells could not protect Rag1-deficient mice from T-cell transfer-induced colitis. Furthermore, Bcl10-deficient Treg cells downregulated the expression of a series of Treg-cell effector and suppressive genes and decreased effector Treg-cell populations. Moreover, Bcl10-deficient Treg cells were converted into IFNγ-producing proinflammatory cells with increased expression of the transcription factors T-bet and HIF-1α. Together, our study results provide genetic evidence, indicating that Bcl10 is required for the development and function of Treg cells.

Reconsidering phosphorylation in the control of inducible CARD11 scaffold activity during antigen receptor signaling

Protein phosphorylation is a commonly used regulatory step that controls signal transduction pathways in a wide array of biological contexts. The finding that a residue is phosphorylated, coupled with the observation that mutation of that residue impacts signaling, often forms the basis for concluding that the phosphorylation of that residue is a key signaling step. However, in certain cases, the situation is more complicated and warrants further study to obtain a clear mechanistic understanding of whether and how the kinase-mediated modification in question is important. CARD11 is a multi-domain signaling scaffold that functions as a hub in lymphocytes to transmit the engagement of antigen receptors into the activation of NF-κB, JNK and mTOR. The phosphorylation of the CARD11 autoinhibitory Inhibitory Domain in response to antigen receptor triggering has been proposed to control the signal-induced conversion of CARD11 from an inactive to an active scaffold in a step required for lymphocyte activation. In this review, I discuss recent data that suggests that this model should be reconsidered for certain phosphorylation events in CARD11 and propose possible experimental avenues for resolution of raised issues.

Critical protein-protein interactions within the CARMA1-BCL10-MALT1 complex: Take-home points for the cell biologist

The CBM complex, which is composed of the proteins CARMA1, BCL10, and MALT1, serves multiple pivotal roles as a mediator of T-cell receptor and B-cell receptor-dependent NF-κB induction and lymphocyte activation. CARMA1, BCL10, and MALT1 are each proto-oncoproteins and dysregulation of CBM signaling, as a result of somatic gain-of-function mutation or chromosomal translocation, is a hallmark of multiple lymphoid malignancies including Activated B-cell Diffuse Large B-cell Lymphoma. Moreover, loss-of-function as well as gain-of-function germline mutations in CBM complex proteins have been associated with a range of immune dysregulation syndromes. A wealth of detailed structural information has become available over the past decade through meticulous interrogation of the interactions between CBM components. Here, we review key findings regarding the biochemical nature of these protein-protein interactions which have ultimately led the field to a sophisticated understanding of how these proteins assemble into high-order filamentous CBM complexes. To date, approaches to therapeutic inhibition of the CBM complex for the treatment of lymphoid malignancy and/or auto-immunity have focused on blocking MALT1 protease function. We also review key studies relating to the structural impact of MALT1 protease inhibitors on key protein-protein interactions.

Gain-of-function mutations in CARD11 promote enhanced aggregation and idiosyncratic signalosome assembly

BENTA (B cell Expansion with NF-κB and T cell Anergy) is a novel lymphoproliferative disorder caused by germline, gain-of-function (GOF) mutations in the lymphocyte-restricted scaffolding protein CARD11. Similar somatic CARD11 mutations are found in lymphoid malignancies such as diffuse large B cell lymphoma (DLBCL). Normally, antigen receptor (AgR) engagement converts CARD11 into an active conformation that nucleates a signalosome required for IκB kinase (IKK) activation and NF-κB nuclear translocation. However, GOF CARD11 mutants drive constitutive NF-κB activity without AgR stimulation. Here we show that unlike wild-type CARD11, GOF CARD11 mutants can form large, peculiar cytosolic protein aggregates we term mCADS (mutant CARD11 dependent shells). MALT1 and phospho-IKK are reliably colocalized with mCADS, indicative of active signaling. Moreover, endogenous mCADS are detectable in ABC-DLBCL lines harboring similar GOF CARD11 mutations. The unique aggregation potential of GOF CARD11 mutants may represent a novel therapeutic target for treating BENTA or DLBCL.

Germline CBM-opathies: From immunodeficiency to atopy

Caspase recruitment domain (CARD) protein-B cell CLL/lymphoma 10 (BCL10)-MALT1 paracaspase (MALT1) [CBM] complexes are critical signaling adaptors that facilitate immune and inflammatory responses downstream of both cell surface and intracellular receptors. Germline mutations that alter the function of members of this complex (termed CBM-opathies) cause a broad array of clinical phenotypes, ranging from profound combined immunodeficiency to B-cell lymphocytosis. With an increasing number of patients being described in recent years, the clinical spectrum of diseases associated with CBM-opathies is rapidly expanding and becoming unexpectedly heterogeneous. Here we review major discoveries that have shaped our understanding of CBM complex biology, and we provide an overview of the clinical presentation, diagnostic approach, and treatment options for those carrying germline mutations affecting CARD9, CARD11, CARD14, BCL10, and MALT1.

Coordinated regulation of scaffold opening and enzymatic activity during CARD11 signaling

The activation of key signaling pathways downstream of antigen receptor engagement is critically required for normal lymphocyte activation during the adaptive immune response. CARD11 is a multidomain signaling scaffold protein required for antigen receptor signaling to NF-κB, c-Jun N-terminal kinase, and mTOR. Germline mutations in the CARD11 gene result in at least four types of primary immunodeficiency, and somatic CARD11 gain-of-function mutations drive constitutive NF-κB activity in diffuse large B cell lymphoma and other lymphoid cancers. In response to antigen receptor triggering, CARD11 transitions from a closed, inactive state to an open, active scaffold that recruits multiple signaling partners into a complex to relay downstream signaling. However, how this signal-induced CARD11 conversion occurs remains poorly understood. Here we investigate the role of Inducible Element 1 (IE1), a short regulatory element in the CARD11 Inhibitory Domain, in the CARD11 signaling cycle. We find that IE1 controls the signal-dependent Opening Step that makes CARD11 accessible to the binding of cofactors, including Bcl10, MALT1, and the HOIP catalytic subunit of the linear ubiquitin chain assembly complex. Surprisingly, we find that IE1 is also required at an independent step for the maximal activation of HOIP and MALT1 enzymatic activity after cofactor recruitment to CARD11. This role of IE1 reveals that there is an Enzymatic Activation Step in the CARD11 signaling cycle that is distinct from the Cofactor Association Step. Our results indicate that CARD11 has evolved to actively coordinate scaffold opening and the induction of enzymatic activity among recruited cofactors during antigen receptor signaling.

Structures of autoinhibited and polymerized forms of CARD9 reveal mechanisms of CARD9 and CARD11 activation

CARD9 and CARD11 drive immune cell activation by nucleating Bcl10 polymerization, but are held in an autoinhibited state prior to stimulation. Here, we elucidate the structural basis for this autoinhibition by determining the structure of a region of CARD9 that includes an extensive interface between its caspase recruitment domain (CARD) and coiled-coil domain. We demonstrate, for both CARD9 and CARD11, that disruption of this interface leads to hyperactivation in cells and to the formation of Bcl10-templating filaments in vitro, illuminating the mechanism of action of numerous oncogenic mutations of CARD11. These structural insights enable us to characterize two similar, yet distinct, mechanisms by which autoinhibition is relieved in the course of canonical CARD9 or CARD11 activation. We also dissect the molecular determinants of helical template assembly by solving the structure of the CARD9 filament. Taken together, these findings delineate the structural mechanisms of inhibition and activation within this protein family.

Hypomorphic caspase activation and recruitment domain 11 (CARD11) mutations associated with diverse immunologic phenotypes with or without atopic disease

BACKGROUND

Caspase activation and recruitment domain 11 (CARD11) encodes a scaffold protein in lymphocytes that links antigen receptor engagement with downstream signaling to nuclear factor κB, c-Jun N-terminal kinase, and mechanistic target of rapamycin complex 1. Germline CARD11 mutations cause several distinct primary immune disorders in human subjects, including severe combined immune deficiency (biallelic null mutations), B-cell expansion with nuclear factor κB and T-cell anergy (heterozygous, gain-of-function mutations), and severe atopic disease (loss-of-function, heterozygous, dominant interfering mutations), which has focused attention on CARD11 mutations discovered by using whole-exome sequencing.

OBJECTIVES

We sought to determine the molecular actions of an extended allelic series of CARD11 and to characterize the expanding range of clinical phenotypes associated with heterozygous CARD11 loss-of-function alleles.

METHODS

Cell transfections and primary T-cell assays were used to evaluate signaling and function of CARD11 variants.

RESULTS

Here we report on an expanded cohort of patients harboring novel heterozygous CARD11 mutations that extend beyond atopy to include other immunologic phenotypes not previously associated with CARD11 mutations. In addition to (and sometimes excluding) severe atopy, heterozygous missense and indel mutations in CARD11 presented with immunologic phenotypes similar to those observed in signal transducer and activator of transcription 3 loss of function, dedicator of cytokinesis 8 deficiency, common variable immunodeficiency, neutropenia, and immune dysregulation, polyendocrinopathy, enteropathy, X-linked-like syndrome. Pathogenic variants exhibited dominant negative activity and were largely confined to the CARD or coiled-coil domains of the CARD11 protein.

CONCLUSION

These results illuminate a broader phenotypic spectrum associated with CARD11 mutations in human subjects and underscore the need for functional studies to demonstrate that rare gene variants encountered in expected and unexpected phenotypes must nonetheless be validated for pathogenic activity.

A Unique Heterozygous CARD11 Mutation Combines Pathogenic Features of Both Gain- and Loss-of-Function Patients in a Four-Generation Family

CARD11 is a lymphocyte-specific scaffold molecule required for proper activation of B- and T-cells in response to antigen. Germline gain-of-function (GOF) mutations in the CARD11 gene cause a unique B cell lymphoproliferative disorder known as B cell Expansion with NF-κB and T cell Anergy (BENTA). In contrast, patients carrying loss-of-function (LOF), dominant negative (DN) CARD11 mutations present with severe atopic disease. Interestingly, both GOF and DN CARD11 variants cause primary immunodeficiency, with recurrent bacterial and viral infections, likely resulting from impaired adaptive immune responses. This report describes a unique four-generation family harboring a novel heterozygous germline indel mutation in CARD11 (c.701-713delinsT), leading to one altered amino acid and a deletion of 4 others (p.His234_Lys238delinsLeu). Strikingly, affected members exhibit both moderate B cell lymphocytosis and atopic dermatitis/allergies. Ectopic expression of this CARD11 variant stimulated constitutive NF-κB activity in T cell lines, similar to other BENTA patient mutations. However, unlike other GOF mutants, this variant significantly impeded the ability of wild-type CARD11 to induce NF-κB activation following antigen receptor ligation. Patient lymphocytes display marked intrinsic defects in B cell differentiation and reduced T cell responsiveness in vitro. Collectively, these data imply that a single heterozygous CARD11 mutation can convey both GOF and DN signaling effects, manifesting in a blended BENTA phenotype with atopic features. Our findings further emphasize the importance of balanced CARD11 signaling for normal immune responses.

Mechanisms of Regulated and Dysregulated CARD11 Signaling in Adaptive Immunity and Disease

CARD11 functions as a key signaling scaffold that controls antigen-induced lymphocyte activation during the adaptive immune response. Somatic mutations in CARD11 are frequently found in Non-Hodgkin lymphoma, and at least three classes of germline CARD11 mutations have been described as the basis for primary immunodeficiency. In this review, we summarize our current understanding of how CARD11 signals, how its activity is regulated, and how mutations bypass normal regulation to cause disease.

The CBM-opathies-A Rapidly Expanding Spectrum of Human Inborn Errors of Immunity Caused by Mutations in the CARD11-BCL10-MALT1 Complex

The caspase recruitment domain family member 11 (CARD11 or CARMA1)-B cell CLL/lymphoma 10 (BCL10)-MALT1 paracaspase (MALT1) [CBM] signalosome complex serves as a molecular bridge between cell surface antigen receptor signaling and the activation of the NF-κB, JNK, and mTORC1 signaling axes. This positions the CBM complex as a critical regulator of lymphocyte activation, proliferation, survival, and metabolism. Inborn errors in each of the CBM components have now been linked to a diverse group of human primary immunodeficiency diseases termed "CBM-opathies." Clinical manifestations range from severe combined immunodeficiency to selective B cell lymphocytosis, atopic disease, and specific humoral defects. This surprisingly broad spectrum of phenotypes underscores the importance of "tuning" CBM signaling to preserve immune homeostasis. Here, we review the distinct clinical and immunological phenotypes associated with human CBM complex mutations and introduce new avenues for targeted therapeutic intervention.

CTD-2020K17.1, a Novel Long Non-Coding RNA, Promotes Migration, Invasion, and Proliferation of Serous Ovarian Cancer Cells In Vitro

Background

Ovarian cancer is the most lethal malignant tumor of the female reproductive system, and the metastasis is one of the major factors that contribute to the poor outcome of patients with OC. Accumulating evidence indicates that lncRNAs are expressed and play important regulatory roles in ovarian cancer.

Material/Methods

Aberrant lncRNAs in primary ovarian cancer tissues (POCTs) and paired omental metastasis tissues (OMTs) of patients with HGSOC were studied via lncRNA microarray. Real-time PCR was performed to examine CTD-2020K17.1 expression in HGSOC tissues from 38 patients, a normal ovarian surface epithelium cell line, and 4 ovarian cancer cell lines. Additionally, Transwell assays, wound healing assays, CCK-8 proliferation assays, and flow cytometry were used to explore the biological function of CTD-2020K17.1 in ovarian cancer cells. Finally, Western blot analysis was used to verify the potential target gene of CTD-2020K17.1.

Results

A novel lncRNA named CTD-2020K17.1 was identified via microarray analysis. Expression of CTD-2020K17.1 was significantly increased in OMTs and in 4 ovarian cancer cell lines compared with POCTs (P<0.05) or normal ovarian surface epithelial cell line (P<0.05). Moreover, CTD-2020K17.1 overexpression promoted migration, invasion, and proliferation of ovarian cancer cells, and CTD-2020K17.1 regulated the expression of CARD11.

Conclusions

CTD-2020K17.1 is significantly upregulated in OMTs and ovarian cancer cell lines. It can promote the migration, invasion, and proliferation of ovarian cancer cells, and CARD11 is regulated by CTD-2020K17.1.

Impaired Control of Epstein-Barr Virus Infection in B-Cell Expansion with NF-κB and T-Cell Anergy Disease

B-cell expansion with NF-κB and T-cell anergy (BENTA) disease is a B-cell-specific lymphoproliferative disorder caused by germline gain-of-function mutations in CARD11. These mutations force the CARD11 scaffold into an open conformation capable of stimulating constitutive NF-κB activation in lymphocytes, without requiring antigen receptor engagement. Many BENTA patients also suffer from recurrent infections, with 7 out of 16 patients exhibiting chronic, low-grade Epstein–Barr virus (EBV) viremia. In this mini-review, we discuss EBV infection in the pathogenesis and clinical management of BENTA disease, and speculate on mechanisms that could explain inadequate control of viral infection in BENTA patients.

Combined immunodeficiency and atopy caused by a dominant negative mutation in caspase activation and recruitment domain family member 11 (CARD11)

BACKGROUND

Combined immunodeficiency (CID) is a T-cell defect frequently presenting with recurrent infections, as well as associated immune dysregulation manifesting as autoimmunity or allergic inflammation.

OBJECTIVE

We sought to identify the genetic aberration in 4 related patients with CID, early-onset asthma, eczema, and food allergies, as well as autoimmunity.

METHODS

We performed whole-exome sequencing, followed by Sanger confirmation, assessment of the genetic variant effect on cell signaling, and evaluation of the resultant immune function.

RESULTS

A heterozygous novel c.C88T 1-bp substitution resulting in amino acid change R30W in caspase activation and recruitment domain family member 11 (CARD11) was identified by using whole-exome sequencing and segregated perfectly to family members with severe atopy only but was not found in healthy subjects. We demonstrate that the R30W mutation results in loss of function while also exerting a dominant negative effect on wild-type CARD11. The CARD11 defect altered the classical nuclear factor κB pathway, resulting in poor in vitro T-cell responses to mitogens and antigens caused by reduced secretion of IFN-γ and IL-2.

CONCLUSION

Unlike patients with biallelic mutations in CARD11 causing severe CID, the R30W defect results in a less profound yet prominent susceptibility to infections, as well as multiorgan atopy and autoimmunity.

Intrinsic Plasma Cell Differentiation Defects in B Cell Expansion with NF-κB and T Cell Anergy Patient B Cells

B cell Expansion with NF-κB and T cell Anergy (BENTA) disease is a novel B cell lymphoproliferative disorder caused by germline, gain-of-function mutations in the lymphocyte scaffolding protein CARD11, which drives constitutive NF-κB signaling. Despite dramatic polyclonal expansion of naive and immature B cells, BENTA patients also present with signs of primary immunodeficiency, including markedly reduced percentages of class-switched/memory B cells and poor humoral responses to certain vaccines. Using purified naive B cells from our BENTA patient cohort, here we show that BENTA B cells exhibit intrinsic defects in B cell differentiation. Despite a profound in vitro survival advantage relative to normal donor B cells, BENTA patient B cells were severely impaired in their ability to differentiate into short-lived IgD^loCD38^hi plasmablasts or CD138⁺ long-lived plasma cells in response to various stimuli. These defects corresponded with diminished IgG antibody production and correlated with poor induction of specific genes required for plasma cell commitment. These findings provide important mechanistic clues that help explain both B cell lymphocytosis and humoral immunodeficiency in BENTA disease.

Molecular Determinants of Scaffold-induced Linear Ubiquitinylation of B Cell Lymphoma/Leukemia 10 (Bcl10) during T Cell Receptor and Oncogenic Caspase Recruitment Domain-containing Protein 11 (CARD11) Signaling

The activation of NF-κB downstream of T cell receptor (TCR) engagement is a key signaling step required for normal lymphocyte function during the adaptive immune response. During TCR signaling, the adaptor protein Bcl10 is inducibly recruited to the CARD11 scaffold protein as part of a multicomponent complex that induces IκB kinase (IKK) activity and NF-κB activation. Here, we show that a consequence of this recruitment is the TCR-induced conjugation of Bcl10 with linear-linked polyubiquitin chains to generate the signaling intermediate Lin(Ub)_n-Bcl10, which is required for the association of Bcl10 with the NEMO subunit of the IKK complex. The TCR-induced generation of Lin(Ub)_n-Bcl10 requires Bcl10 lysines 17, 31, and 63, CARD11, MALT1, and the HOIP subunit of the linear ubiquitin chain assembly complex (LUBAC) but not the HOIP accessory protein SHARPIN. CARD11 promotes signal-induced Lin(Ub)_n-Bcl10 generation by co-recruiting Bcl10 with HOIP, thereby bringing substrate to enzyme. The CARD11-HOIP interaction is rendered TCR-inducible by the four autoinhibitory repressive elements in the CARD11 inhibitory domain and involves the CARD11 coiled-coil domain and two independent regions of HOIP. Interestingly, oncogenic CARD11 variants associated with diffuse large B cell lymphoma spontaneously induce Lin(Ub)_n-Bcl10 production to extents that correlate with their abilities to activate NF-κB and with their enhanced abilities to bind HOIP and Bcl10. Our results define molecular determinants that control the production of Lin(Ub)_n-Bcl10, an important signaling intermediate in TCR and oncogenic CARD11 signaling.

Intramolecular Interactions and Regulation of Cofactor Binding by the Four Repressive Elements in the Caspase Recruitment Domain-containing Protein 11 (CARD11) Inhibitory Domain

The CARD11 signaling scaffold transmits signaling between antigen receptors on B and T lymphocytes and the transcription factor NF-κB during the adaptive immune response. CARD11 activity is controlled by an inhibitory domain (ID), which participates in intramolecular interactions and prevents cofactor binding prior to receptor triggering. Oncogenic CARD11 mutations associated with the activated B cell-like subtype of diffuse large B cell lymphoma somehow perturb ID-mediated autoinhibition to confer CARD11 with the dysregulated spontaneous signaling to NF-κB that is required for the proliferation and survival of the lymphoma. Here, we investigate how the four repressive elements (REs) we have discovered in the CARD11 ID function to inhibit CARD11 activity with cooperativity and redundancy. We find that each RE contributes to the maintenance of the closed inactive state of CARD11 that predominates in the absence of receptor engagement. Each RE also contributes to the prevention of Bcl10 binding in the basal unstimulated state. RE1, RE2, and RE3 participate in intramolecular interactions with other CARD11 domains and share domain targets for binding. Remarkably, diffuse large B cell lymphoma-associated gain-of-function mutations in the caspase recruitment domain, LATCH, or coiled coil can perturb intramolecular interactions mediated by multiple REs, suggesting how single amino acid oncogenic CARD11 mutations can perturb or bypass the action of redundant inhibitory REs to achieve the level of hyperactive CARD11 signaling required to support lymphoma growth.