Project description:At the epigenetic level, lncRNAs play important roles in cell differentiation and function. We identified novel long-stranded non-coding RNA (GM1082) in BMDMs, which may play an important role in macrophage differentiation and function.To confirm the interaction between LNCRNA and NLRC4 and Caspase11, we performed RNA immunoprecipitation using NLRC4 and Caspase11 antibodies, and high-throughput sequencing of the obtained RNA.
Project description:Inflammasome activation is critical for host defense against various microbial infections. Activation of the NLRC4 inflammasome requires detection of flagellin or type III secretion system (T3SS) components by NLR family apoptosis inhibitory proteins (NAIPs); yet how this pathway is regulated is unknown. Here we found that interferon regulatory factor 8 (IRF8) is required for optimal activation of the NLRC4 inflammasome in bone marrow-derived macrophages infected with Salmonella Typhimurium, Burkholderia thailandensis, or Pseudomonas aeruginosa but is dispensable for activation of the canonical and non-canonical NLRP3, AIM2, and Pyrin inflammasomes. IRF8 governs the transcription of Naips to allow detection of flagellin or T3SS proteins to mediate NLRC4 inflammasome activation. Furthermore, we found that IRF8 confers protection against bacterial infection in vivo, owing to its role in inflammasome-dependent cytokine production and pyroptosis. Altogether, our findings suggest that IRF8 is a critical regulator of NAIPs and NLRC4 inflammasome activation for defense against bacterial infection.
Project description:Inflammasomes are intracellular innate immune sensors that respond to pathogen and damage-associated signals with the proteolytic cleavage of caspase-1, resulting in IL-1_ and IL-18 secretion and macrophage pyroptosis. The discovery that heterozygous gain-of-function mutations in NLRP3 lead to oversecretion of IL-1_ and cause the autoinflammatory disease spectrum Cryopyrin Associated Periodic Syndrome (CAPS), led to the successful use of IL-1 blocking therapies1. We found that a de novo missense mutation in the regulatory domain of the NLRC4 (IPAF, CARD12) inflammasome causes early-onset recurrent fever flares and Macrophage Activation Syndrome (MAS). Functional analyses demonstrated spontaneous production of the inflammasome-dependent cytokines IL-1² and IL-18 exceeding levels in CAPS patients. The NLRC4 mutation led to constitutive caspase-1 cleavage in transduced cells and enhanced spontaneous production of IL-18 by both patient and NLRC4 mutant macrophages. Thus, we describe a novel monoallelic inflammasome defect that expands the autoinflammatory paradigm to include MAS and suggests novel targets for therapy. Whole blood RNA-seq from seven timepoints of one patient with NLRC4-MAS as compared to five healthy pediatric controls, 7 NOMID patients with active disease prior to anakinra treatment and the same 7 NOMID patients with inactive disease after anakinra treatment. Please note that seven time points are chronologic time point. They are ordinal, in that "1" was drawn before "2", but the distance in time between points is not constant. Thus, time points 4 through 7 correspond to samples drawn while the patient was well AND on treatment. However there may be differences between 4 and 7 pertaining to the length of treatment, and for that reason any of these samples were not considered replicates.
Project description:The mammalian genome contains thousands of loci that transcribe long noncoding RNAs (lncRNAs), some of which are known to play critical roles in diverse cellular processes through a variety of mechanisms. While some lncRNA loci encode RNAs that act non-locally (in trans), emerging evidence indicates that many lncRNA loci act locally (in cis) to regulate expression of nearby genes—for example, through functions of the lncRNA promoter, transcription, or transcript itself. Despite their potentially important roles, it remains challenging to identify functional lncRNA loci and distinguish among these and other mechanisms. To address these challenges, we developed a genome-scale CRISPR-Cas9 activation screen targeting more than 10,000 lncRNA transcriptional start sites (TSSs) to identify noncoding loci that influence a phenotype of interest. We found 11 novel lncRNA loci that, upon recruitment of an activator, each mediate BRAF inhibitor resistance in melanoma. Most candidate loci appear to regulate nearby genes. Detailed analysis of one candidate, termed EMICERI, revealed that its transcriptional activation results in dosage-dependent activation of four neighboring protein-coding genes, one of which confers the resistance phenotype. Our screening and characterization approach provides a CRISPR toolkit to systematically discover functions of noncoding loci and elucidate their diverse roles in gene regulation and cellular function.
Project description:Long noncoding RNAs (lncRNAs) have been implicated in controlling various aspects of embryonic stem cell (ESC) biology, although the functions of specific lncRNAs, and the molecular mechanisms through which they act, remain unclear. Here, we demonstrate discrete and opposing roles for the lncRNA transcript Haunt and its genomic locus in regulating the HOXA gene cluster during ESC differentiation. Reducing or enhancing Haunt expression, with minimal disruption of the Haunt locus, led to up- or down-regulation of HOXA genes, respectively. In contrast, increasingly large genomic deletions within the Haunt locus attenuated HOXA activation. The Haunt DNA locus contains potential enhancers of HOXA activation, whereas Haunt RNA acts to prevent aberrant HOXA expression. This work reveals a multi-faceted model of lncRNA-mediated transcriptional regulation of the HOXA cluster, with distinct roles for a lncRNA transcript and its genomic locus, while illustrating the power of rapid CRISPR/Cas9-based genome editing for assigning lncRNA functions. All RNA-seq(s) were designed to reveal the differentially expressed genes among different stages of ESCs differentiation, or differentially expressed genes between wild-type or Haunt or HOXA mutant cells during RA-induced differentiation. All ChIRP-Seq were used to reveal the DNA or RNA targets of Haunt before or after RA treatment.
Project description:Bacterial flagellin is a dominant innate immune activator of the intestine. Therefore, we examined the role of the intracellular flagellin receptor, NLRC4, in protecting the gut and/or driving inflammation. In accord with NLRC4 acting via transcription-independent pathways, loss of NLRC4 did not reduce the rapid robust changes in intestinal gene expression induced by flagellin administration. Loss of NLRC4 did not alter basal intestinal homeostasis nor predispose mice to development of colitis upon administration of an anti-IL-10R monoclonal antibody. However, in response to epithelial injury induced by dextran sulfate sodium (DSS), loss of NLRC4 resulted in more severe disease indicating a role for NLRC4 in protecting the gut. Moreover, loss of NLRC4 resulted in increased mortality in response to flagellate, but not aflagellate Salmonella infection. Thus, despite not being involved in rapid intestinal gene remodeling upon detection of flagellin, NLRC4-mediated inflammasome activation protects mice from mucosal and systemic challenges Flagellin (FliC) from WT Salmonella enterica serovar Typhimurium (SL3201, fljB–) was purified through sequential cation and anion-exchange chromatography and purity was verified as previously described 4. WT, T5KO, N4KO and T5/N4-DKO mice (n=6) were given either 0.2 mL PBS or flagellin (10μg/mouse in 0.2 mL PBS) intraperitoneally. After 1h, mice were euthanized and colon was taken and stored in RNAlater (Invitrogen) for 1 day. Total mRNA was isolated from colonic tissues using TRIzol (Invitrogen) and purified using the RNeasy® Plus Mini kit (Qiagen) according to the manufacturer’s instructions
Project description:Inflammasomes are intracellular innate immune sensors that respond to pathogen and damage-associated signals with the proteolytic cleavage of caspase-1, resulting in IL-1_ and IL-18 secretion and macrophage pyroptosis. The discovery that heterozygous gain-of-function mutations in NLRP3 lead to oversecretion of IL-1_ and cause the autoinflammatory disease spectrum Cryopyrin Associated Periodic Syndrome (CAPS), led to the successful use of IL-1 blocking therapies1. We found that a de novo missense mutation in the regulatory domain of the NLRC4 (IPAF, CARD12) inflammasome causes early-onset recurrent fever flares and Macrophage Activation Syndrome (MAS). Functional analyses demonstrated spontaneous production of the inflammasome-dependent cytokines IL-1² and IL-18 exceeding levels in CAPS patients. The NLRC4 mutation led to constitutive caspase-1 cleavage in transduced cells and enhanced spontaneous production of IL-18 by both patient and NLRC4 mutant macrophages. Thus, we describe a novel monoallelic inflammasome defect that expands the autoinflammatory paradigm to include MAS and suggests novel targets for therapy.
Project description:The mammalian genome contains thousands of loci that transcribe long noncoding RNAs (lncRNAs), some of which are known to play critical roles in diverse cellular processes through a variety of mechanisms. While some lncRNA loci encode RNAs that act non-locally (in trans), emerging evidence indicates that many lncRNA loci act locally (in cis) to regulate expression of nearby genes—for example, through functions of the lncRNA promoter, transcription, or transcript itself. Despite their potentially important roles, it remains challenging to identify functional lncRNA loci and distinguish among these and other mechanisms. To address these challenges, we developed a genome-scale CRISPR-Cas9 activation screen targeting more than 10,000 lncRNA transcriptional start sites (TSSs) to identify noncoding loci that influence a phenotype of interest. We found 11 novel lncRNA loci that, upon recruitment of an activator, each mediate BRAF inhibitor resistance in melanoma. Most candidate loci appear to regulate nearby genes. Detailed analysis of one candidate, termed EMICERI, revealed that its transcriptional activation results in dosage-dependent activation of four neighboring protein-coding genes, one of which confers the resistance phenotype. Our screening and characterization approach provides a CRISPR toolkit to systematically discover functions of noncoding loci and elucidate their diverse roles in gene regulation and cellular function.
Project description:Bacterial flagellin is a dominant innate immune activator of the intestine. Therefore, we examined the role of the intracellular flagellin receptor, NLRC4, in protecting the gut and/or driving inflammation. In accord with NLRC4 acting via transcription-independent pathways, loss of NLRC4 did not reduce the rapid robust changes in intestinal gene expression induced by flagellin administration. Loss of NLRC4 did not alter basal intestinal homeostasis nor predispose mice to development of colitis upon administration of an anti-IL-10R monoclonal antibody. However, in response to epithelial injury induced by dextran sulfate sodium (DSS), loss of NLRC4 resulted in more severe disease indicating a role for NLRC4 in protecting the gut. Moreover, loss of NLRC4 resulted in increased mortality in response to flagellate, but not aflagellate Salmonella infection. Thus, despite not being involved in rapid intestinal gene remodeling upon detection of flagellin, NLRC4-mediated inflammasome activation protects mice from mucosal and systemic challenges