Project description:In this study, we performed RNA-seq to seek lncRNAs which changed significantly on expression in RAW264.7 cells before and after vesicular stomatitis virus (VSV) infection. For further investigation, we used iCLIP-seq technologies to identify the exact interaction sites between TDP43 protein and long non-coding RNA malat1 in mouse macrophages.
Project description:Long noncoding RNAs (lncRNAs) involved in the regulation of antiviral innate immune responses need to be further identified. By functionally screening the lncRNAs in macrophages, here we identified lncRNA Malat1, abundant in the nucleus but significantly down-regulated after viral infection, as a negative regulator of antiviral type I IFN (IFN-I) production. Malat1 directly bound to the transactive response DNA-binding protein (TDP43) in the nucleus and prevented activation of TDP43 by blocking the activated caspase-3-mediated TDP43 cleavage to TDP35. The cleaved TDP35 increased the nuclear IRF3 protein level by binding and degrading Rbck1 pre-mRNA to prevent IRF3 proteasomal degradation upon viral infection, thus selectively promoting antiviral IFN-I production. Deficiency of Malat1 enhanced antiviral innate responses in vivo, accompanying the increased IFN-I production and reduced viral burden. Importantly, the reduced MALAT1, augmented IRF3, and increased IFNA mRNA were found in peripheral blood mononuclear cells (PBMCs) from systemic lupus erythematosus (SLE) patients. Therefore, the down-regulation of MALAT1 in virus-infected cells or in human cells from autoimmune diseases will increase host resistance against viral infection or lead to autoinflammatory interferonopathies via the increased type I IFN production. Our results demonstrate that the nuclear Malat1 suppresses antiviral innate responses by targeting TDP43 activation via RNA-RBP interactive network, adding insight to the molecular regulation of innate responses and autoimmune pathogenesis.
Project description:The majority of individuals with amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) exhibit neuronal cytoplasmic inclusions rich in the RNA binding protein TDP43. Even so, the relationship between TDP43’s RNA binding properties and neurodegeneration remain obscure. Here we show that engineered mutations disrupting a salt bridge between TDP43’s RNA recognition motifs interfere with nucleic acid binding and eliminate recognition of native TDP43 substrates. The accumulation of WT TDP43, but not RNA binding-deficient variants, disproportionately affected the abundance and splicing of encoding ribosome and oxidative phosphorylation components.
Project description:TDP43 is involved in microRNA biogenesis and found in cytoplasmic aggregates in amyotrophic lateral sclerosis (ALS), and microRNAs are important for regulation of gene expression and represent potential biomarkers and therapeutic targets. Therefore, we examined microRNAs that preferentially bind cytoplasmic TDP43 using cellular models expressing TDP43 variants and NanoString miRNA profiling analyses. We identified cytoplasmic TDP43-associated miRNAs and predicted genes and pathways to gain insights into potentially relevant disease pathways, biomarkers, and reversible therapeutic targets for ALS.
Project description:Previously, lncRNA Malat1 knockout mice were generated by insertional inactivation. By crossing this line to MMTV-PyMT mammary tumor mouse model, we produced PyMT;Malat1 wild-type (WT) and PyMT;Malat1 knockout (KO). Furthermore, we generated Malat1 transgenic mice by targeting ROSA26 locus and bred them to PyMT;Malat1 knockout mice to produce Malat1-rescued PyMT;Malat1 knockout;Malat1 transgenic animals (TG). Using mammary tumors from the three groups of animals, we performed RNA-Seq analysis to identify differentially up-regulated genes in KO tumors to find novel target genes of YAP-TEAD pathway.
Project description:The interferon regulatory factors IRF3 and IRF7 are key players in the regulation of type I and III IFN genes. In this study, we analyzed the role of IRF3 and IRF7 for the host response to influenza A virus infections in Irf3-/-, Irf7-/- and Irf3-/-Irf7-/- knock-out mice.
Project description:IRF3 is one of the most critical transcription factor in down stream of pattern recognition receptors (such as toll-like receptor and RIG-I-like receptor) signalling pathway. IRF3 is known to induce the expression of type I IFN gene upon virus infection. To furter examine the role of IRF3 in virus-induced gene expression, we preformed microarray analysis in IRF3-/- peritoneal macrophages infected with VSV, and found that IRF3 suppresses the expression of Il12b gene. Peritoneal macrophages from WT of IRF3-/- B6 mice were infected with VSV(1 M.O.I. ) for 6 hous, and then subjected to microarray analysis.
Project description:Mislocalization of the nuclear protein TDP43 is a hallmark of ALS and FTD and leads to de-repression and inclusion of cryptic exons, which represent promising biomarkers of TDP43 pathology. However, most cryptic exons to date have been identified from in vitro models, limiting our understanding of any tissue and/or cell-specific splices. We meta-analyzed published bulk RNA-Seq datasets representing 1,778 RNAseq profiles of ALS and FTD post mortem tissue, and in vitro models with experimentally depleted TDP43. We identified novel cryptic splices and mapped out their tissue-specificity, demonstrating subsets with distinct cortical and spinal cord enrichment. Novel events were validated by RNA-Seq and RT-qPCR in a new spinal cord cohort, and analysis of single-nucleus datasets localized cortical splices to layer-specific neuronal populations. This catalog of cryptic splices is the first step towards the development of biomarkers for cell type-specific TDP43 pathology.
Project description:Malat1 is an abundant long noncoding RNA that localizes to nuclear bodies known as nuclear speckles, which contain a distinct set of pre-mRNA processing factors. Previous in vitro studies have demonstrated that Malat1 interacts with pre-mRNA splicing factors, including the serine- and arginine-rich (SR) family of proteins, and regulates a variety of biological processes, including cancer cell migration, synapse formation, cell cycle progression, and responses to serum stimulation. To address the physiological function of Malat1 in a living organism, we generated Malat1-KO (KO) mice using homologous recombination. Unexpectedly, the Malat1-KO mice were viable and fertile, showing no apparent phenotypes. Nuclear speckle markers were also correctly localized in cells that lacked Malat1. However, the cellular levels of another long noncoding RNA, Neat1, which is an architectural component of nuclear bodies known as paraspeckles, were downregulated in a particular set of tissues and cells lacking Malat1. To address if the the absence of Malat1 affects the expression of other genes, including other long noncoding RNA, microarrays were used to study the impact of knocking-out Malat1 on global gene expression in mouse embryonic fibroblasts (MEFs). MEFs were prepared from E13.5 mouse embryos from wildtype and Malat1 knock-out mice. RNA harvested from these cells were hybridized to Affymetirx mouse gene expression array.