Project description:The goal of this study is to elucidate the role of microglial A20 in maintaining brain homeostasis, comparing fully deficient to partially deficient microglia tissue
Project description:A20 is a ubiquitin-modifying protein that negatively regulates canonical NF-κB signaling and mutations in A20/TNFAIP3 have been associated with a variety of autoimmune diseases, including multiple sclerosis (MS). We found that deletion of A20 in central nervous system (CNS) endothelial cells (BEC) enhances experimental autoimmune encephalomyelitis (EAE), a mouse model of MS. These mice showed increased numbers of CNS-infiltrating immune cells during neuroinflammation and in the steady state. While the integrity of the barrier was not impaired, we observed a strong activation of the endothelium in A20ΔBEC mice, with dramatically increased levels of the adhesion molecules ICAM-1 and VCAM-1. We furthermore discovered ICOSL as novel adhesion molecule expressed by A20-deficient BECs. Silencing of ICOSL in BECs ameliorated the severity of an active EAE disease in wildtype mice and significantly delayed the onset of symptom development. Furthermore, blocking of ICOSL on primary CNS-derived endothelial cells impaired the adhesion of different T cell populations to the monolayer. Taken together, we here report a novel function of A20-regulated ICOSL expressed on CNS endothelial cells during inflammation. We propose that BEC-ICOSL contributes to the firm adhesion of T cells to the barrier, promoting T cell transmigration into the CNS and eventually driving autoimmune neuroinflammation.
Project description:Genetic TNFAIP3 (A20) inactivation is a classical somatic lymphoma lesion and the genomic trait in haploinsufficiency of A20 (HA20). Single-cell sequencing reveals “pre-lymphoma” transcription signatures in lymphocytes of HA20 patients.
Project description:Unique and shared cytogenetic abnormalities have been documented for marginal zone lymphomas (MZLs) arising at different sites. Recently, homozygous deletions of the chromosomal band 6q23, involving the tumor necrosis factor alpha-induced protein 3 (TNFAIP3, A20) gene, a negative regulator of NF-kappa B, were described in ocular adnexal MZL, suggesting a role for A20 as a tumor suppressor in this disease entity. Here, we investigated inactivation of A20 by DNA mutations or deletions in a panel of extranodal (EMZL), nodal (NMZL) and splenic (SMZL) MZLs. Inactivating mutations encoding truncated A20 proteins were identified in 6/32 (18.8%) MZLs, including 3/11 (27.3%) EMZLs, 2/9 (22.2%) NMZLs, and 1/12 (8.3%) SMZLs. Two additional unmutated non-splenic MZLs also showed mono- or biallelic A20 deletions by FISH and/or array-CGH. Thus, A20 loss by both somatic mutations and/or deletions represents a common genetic aberration across all MZL subtypes, which may contribute to lymphomagenesis by inducing constitutive NF-kappa B activation. Keywords: Genome variation profiling by SNP array 27 MZL samples. No technical replications.
Project description:A20 is a negative regulator of NF-κB signaling, crucial to control inflammatory responses and ensure tissue homeostasis. A20 is thought to restrict NF-κB activation both by its ubiquitin-editing activity as by non-enzymatic activities. Besides its role in NF-κB signaling, A20 also acts as a protective factor inhibiting apoptosis and necroptosis. Because of the ability of A20 to both ubiquitinate and deubiquitinate substrates and its involvement in many cellular processes, we hypothesized that deletion of A20 might generally impact on protein levels, thereby disrupting cellular processes. We performed a differential proteomics study of bone marrow derived macrophages (BMDMs) from control and myeloid-specific A20 knockout mice, both in untreated conditions and after LPS and TNF treatment, and demonstrate proteome-wide changes in protein expression upon A20 deletion. Several inflammatory proteins are up-regulated in the absence of A20, even without an inflammatory stimulus. Depending on the treatment and the time, more proteins are regulated. Together these changes may affect multiple signaling pathways disturbing tissue homeostasis and inducing (autoimmune) inflammation, as suggested by genetic studies in patients.
Project description:As the professional phagocyte in the central nervous system (CNS), microglia are the primary scavenger removing cell corpses. The failure of microglia in debris clearance influences the normal CNS function. Meanwhile, microglia undergo turnover during the whole lifespan. If dead microglia are not timely removed, accumulated corpses may influence the CNS function. The microglial corpse clearance is hereby crucial for CNS homeostasis. However, the underlying mechanism remains obscure. In this study, we investigated how microglial corpses are removed. We found that microglial corpses are mainly phagocytosed by astrocytes, mediated by C4b opsonization. Then engulfed microglial fragments are degraded in astrocytes via the RUBICON-dependent LC3-associated phagocytosis (LAP), a form of non-canonical autophagy. The interference of the C4b-mediated engulfment and its subsequent LAP disrupt the microglial debris removal and degradation, respectively. Together, we elucidated cellular and molecular mechanisms of microglial debris removal, extending the knowledge on how the CNS homeostasis is maintained.
Project description:Objectives: Genetic variations in TNFAIP3 (A20) de-ubiquitinase (DUB) domain increase the risk of systemic lupus erythematosus (SLE) and rheumatoid arthritis. A20 is a negative regulator of NF-κB but the role of its DUB domain and related genetic variants remain unclear. We aimed to study the functional effects of A20 DUB-domain alterations in immune cells and understand its link to SLE pathogenesis. Methods: CRISPR/Cas9 was used to generate human U937 monocytes with A20 DUB-inactivating C103A knock-in mutation. Whole genome RNA-sequencing was used to identify differentially expressed genes between WT and C103A knock-in cells. Functional studies were performed in A20 C103A U937 cells and in immune cells from A20 C103A mice and genotyped healthy individuals with A20 DUB polymorphism rs2230926. Neutrophil extracellular trap (NET) formation was adressed ex vivo in neutrophils from A20 C103A mice and SLE-patients with rs2230926. Results: Genetic disruption of A20 DUB domain in human and murine myeoloid cells did not give rise to enhanced NF-κB signaling. Instead, cells with C103A mutation or rs2230926 polymorphism presented an upregulated expression of PADI4, an enzyme regulating protein citrullination and NET formation, two key mechanisms in autoimmune pathology. A20 C103A cells exhibited enhanced protein citrullination and extracellular trap formation, which could be suppressed by selective PAD4 inhibition. Moreover, SLE-patients with rs2230926 showed increased NETs and increased frequency of autoantibodies to citrullinated epitopes. Conclusions: We propose that genetic alterations disrupting the A20 DUB domain mediate increased susceptibility to SLE through the upregulation of PADI4 with resultant protein citrullination and extracellular trap formation.
Project description:Purpose: The goals of this study are to compare the transcriptome profiling (RNA-seq) of different A20 expression in HCT116 cells, to find potiential target genes for A20 mediated immnue escape. Results: There were 352 genes altered after A20 was knocked out with the log-fold >2 or <-2 compared to WT cells, and p value<0.01 . And 143 genes changed after rescued the expression of A20 in A20-KO cells compared to A20-KO cells. Among these altered genes, 13 genes were changes consistently. Conclusion:Gain- and loss-A20 functional studies proved that A20 could decrease the ¡°eat-me¡± signal calreticulin (CRT) protein on cell membranes via stabilizing stanniocalcin 1 (STC1). Mechanistically, A20 inhibited the degradation of STC1 protein which could capture the CRT inside cell rather than to translocated to cell membrane.
Project description:Genome wide transcriptional profiling on liver mRNA retrieved from recombinant adenovirus A20 (rAd.A20) and rAd.bgalactosidase transduced livers, before and 24 hours after 78% extended liver resection. Overexpression of the NF-kB inhibitory protein A20 improves recovery of liver function and mass following extended liver resection and severe liver ischemia reperfusion injury in mice. In this project, we explored effects of A20 using transcriptional profiling on liver mRNA retrieved from recombinant adenovirus A20 (rAd.A20) and rAd.bgalactosidase transduced livers, before and 24 hours after 78% extended liver resection.
Project description:Genome wide transcriptional profiling on liver mRNA retrieved from recombinant adenovirus A20 (rAd.A20) and rAd.bgalactosidase transduced livers, before and 24 hours after 78% extended liver resection. Overexpression of the NF-kB inhibitory protein A20 improves recovery of liver function and mass following extended liver resection and severe liver ischemia reperfusion injury in mice. In this project, we explored effects of A20 using transcriptional profiling on liver mRNA retrieved from recombinant adenovirus A20 (rAd.A20) and rAd.bgalactosidase transduced livers, before and 24 hours after 78% extended liver resection. A20 or beta-galactosidase gene expression in the mouse liver was achieved by penile vein injection of 1x109 pfu of rAd. in 100uL of normal saline, which results in optimal transgene expression 5 days after injection in 30% to 40% of hepatocytes (Longo et al, 2005). Extended (78%) LR, consisting of resection of the lateral, medial, left, and right lobes, was performed 5 days following rAd. administration in 8-week old BALB/c mice weighing 25 to 30 grams (Taconic, Germantown, NY), as described (Longo et al, 2005). RNA was extracted from the resected portion of the liver (before samples) and from the remnant liver 24 hours after resection (after samples). RNA from three animals was pooled per microarray and 2 microarrays per group were performed.