Project description:Post-transcriptional regulatory networks are dependent on the interplay of many RNA-binding proteins having a major role in mRNA processing events in mammals. We have been interested in the concerted action of the two RNA-binding proteins hnRNP A1 and HuR, both stable components of immunoselected hnRNP complexes and having a major nuclear localization. Specifically, we present here the application of the RNA-immunoprecipitation (RIP)-Chip technology to identify a population of nuclear transcripts associated with hnRNP A1-RNPs as isolated from the nuclear extract of either HuR WT or HuR-depleted (KO) mouse embryonic fibroblast (MEF) cells. The outcome of this analysis was a list of target genes regulated via HuR for their association (either increased or reduced) with the nuclear hnRNP A1-RNP complexes. Real time PCR analysis was applied to validate a selected number of nuclear mRNA transcripts, as well as to identify pre-spliced transcripts (in addition to their mature mRNA counterpart) within the isolated nuclear hnRNP A1-RNPs. The differentially enriched mRNAs were found to belong to GO categories relevant to biological processes anticipated for hnRNP A1 and HuR (such as transport, transcription, translation, apoptosis and cell cycle) indicative of their concerted function in mRNA metabolism.
Project description:Experimental autoimmune encephalomyelitis (EAE) is a mouse model for multiple sclerosis (MS) a chronic autoimmune disease of the central nervous system. We have observed dysfunction of the RNA binding protein hnRNP A1 in neurons from the brains of patients with MS, and the spinal cords of mice with EAE. Here, we sought to characterize the consequences of EAE-induced dysfunction of hnRNP A1 on the RNAs it binds by using CLIPseq to establish both the normal central nervous system RNA binding profile of hnRNP A1 in the spinal cords of naive mice, and any alterations to the binding profile of hnRNP A1 in the spinal cords of mice with EAE.
Project description:Post-transcriptional regulatory networks are dependent on the interplay of many RNA-binding proteins having a major role in mRNA processing events in mammals. We have been interested in the concerted action of the two RNA-binding proteins hnRNP A1 and HuR, both stable components of immunoselected hnRNP complexes and having a major nuclear localization. Specifically, we present here the application of the RNA-immunoprecipitation (RIP)-Chip technology to identify a population of nuclear transcripts associated with hnRNP A1-RNPs as isolated from the nuclear extract of either HuR WT or HuR-depleted (KO) mouse embryonic fibroblast (MEF) cells. The outcome of this analysis was a list of target genes regulated via HuR for their association (either increased or reduced) with the nuclear hnRNP A1-RNP complexes. Real time PCR analysis was applied to validate a selected number of nuclear mRNA transcripts, as well as to identify pre-spliced transcripts (in addition to their mature mRNA counterpart) within the isolated nuclear hnRNP A1-RNPs. The differentially enriched mRNAs were found to belong to GO categories relevant to biological processes anticipated for hnRNP A1 and HuR (such as transport, transcription, translation, apoptosis and cell cycle) indicative of their concerted function in mRNA metabolism. Ribonucleoprotein Immunoprecipitation (RIP) using hnRNP A1 specific antibody was performed in nuclear extracts from HuR WT and HuR KO Mouse Embryonic Fibroblasts (MEFs). RNA isolated from these IPs together with nuclear RNA from the two cell types, was subjected to microarray analysis. Three biological replicates, representing three independent experiments, are available for each condition except in the case of nuclear RNA isolated from HuR WT MEFs that one replicate didn’t pass the quality control.
Project description:Bladder cancer (BCa) is one of the most common malignant tumors of urinary system and has high incidence rate and mortality but there is a lack of effective treatment. Therefore, an in-depth study of the molecular mechanisms involved in BCa is of great significance for improving the survival of patients with advanced BCa. We found that the expression of RBMX was significantly declined in BCa, especially in muscle-invasive BCa. BCa patients with low levels of RBMX had poor prognoses. By in vitro and in vivo experiments, RBMX was shown to inhibit BCa cells growth and metastasis. Co-IP coupled with MS and GO analysis identified hnRNP A1 as a RBMX-binding protein. Mechanistically, RBMX competitively bond to the RGG box of hnRNP A1 and antagonized the hnRNP A1-mediated regulation of PKM splicing by blocking the binding of the RGG motif of hnRNP A1 to the sequences flanking PKM exon 9, resulting in downregulation of PKM2 and upregulation of PKM1. By decreasing the PKM2/PKM1 ratio, RBMX suppressed BCa cells aerobic glycolysis, which further inhibited tumorigenicity and progression of BCa.
Project description:Transcriptome analysis of total RNA samples from heart tissue of knockout mice Alternative splicing is the main mechanism to increase protein diversity from an mRNA. Heterogeneous ribonucleoprotein (hnRNP) family members are vital regulators of alternative splicing. The hnRNP A1 is the most well-known protein in this family, but its role in embryonic development is not well understood. We generated hnRNP A1 knockout mice to study the function of hnRNP A1 in vivo. The hnRNP A1-depleted mice showed embryonic lethality because of muscle developmental defects. In a previous study, cellular hnRNP A2/B1 was reported to be capable of compensating for the expression of hnRNP A1. However, this phenomenon did not occur in the hnRNP A1 heterozygous mice in vivo. We demonstrated that hnRNP A1 regulated muscle-related genes expression and alternative splicing. In summary, our data demonstrated that hnRNP A1 plays a critical role in embryonic muscle development. Understanding the effects of hnRNP A1 in vivo may help to define the function of hnRNP A1 in alternative splicing.
Project description:We sought to identify alterations in RNA expression and splicing in human grey matter from the brains of people with Multiple Sclerosis (MS) where we observe mislocalization of the RNA binding protein hnRNP A1. Thus, RNA was extracted from fresh-frozen post-mortem brain samples of three people with MS and compared to RNA extracted from fresh-frozen post-mortem brain samples of three healthy controls by RNAseq. Regions of interest in human grey matter were defined by immunostaining for hnRNP A1 to confirm grey matter regions with hnRNP A1 mislocalization in MS tissue, and grey matter regions with normal hnRNP A1 localization in control tissue, and the same region from an adjacent tissue section was dissected with a razor blade and used for RNA extraction and sequencing.
Project description:During the maternal-to-zygotic transition (MZT), transcriptionally silent embryos rely on post-transcriptional regulation of maternal mRNAs until zygotic genome activation (ZGA). RNA-binding proteins (RBPs) are important regulators of post-transcriptional RNA processing events, yet their identities and functions during developmental transitions in vertebrates remain largely unexplored. Using mRNA interactome capture, we identified 227 RBPs in zebrafish embryos before and during ZGA, hereby named the zebrafish MZT mRNAbound proteome. This protein constellation consists of many conserved RBPs, with additional embryo- and stage-specific mRNA interactors that likely reflect the dynamics of RNA-protein interactions during MZT. The enrichment of numerous splicing factors like hnRNP proteins before ZGA was surprising, because maternal mRNAs were found to be fully spliced. To address potentially unique roles of RBPs in embryogenesis, we focused on hnRNP A1. iCLIP and subsequent mRNA reporter assays revealed a function for hnRNP A1 in the regulation of poly(A) tail length and translation of maternal mRNAs through sequence-specific association with 3’UTRs before ZGA. Comparison of iCLIP data from two developmental stages revealed that hnRNP A1 dissociates from maternal mRNAs at ZGA and instead regulates the nuclear processing of pri-miR-430 transcripts, which we validated experimentally. The shift from cytoplasmic to nuclear RNA targets was accompanied by a dramatic translocation of hnRNP A1 and other pre-mRNA splicing factors to the nucleus in a transcription-dependent manner. Thus, our study identifies global changes in RNA-protein interactions during vertebrate MZT and shows that hnRNP A1 RNA-binding activities are spatially and temporally coordinated to regulate RNA metabolism during early development.
Project description:This experiment identifies hnRNP A1 binding sites transcriptome-wide in Hela cells. HeLa cells with inducible expression of T7-tagged hnRNP A1 were grown to approximately 90% confluence and then subject to iCLIP analysis (following the protocol from Huppertz et al. 2014 (iCLIP: protein-RNA interactions at nucleotide resolution)). The iCLIP library was sequenced using Illumina's HighSeq 1500