Top3β is an RNA topoisomerase that works with Fragile X syndrome protein to promote synapse formation
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE47502 | GEO | 2013/08/04
SECONDARY ACCESSION(S): PRJNA205898
REPOSITORIES: GEO
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Project description:Topoisomerases are crucial to solve DNA topological problems, but they have not been linked to RNA metabolism. Here we show that human topoisomerase 3M-NM-2 (Top3M-NM-2) is an RNA topoisomerase that biochemically and genetically interacts with FMRP, a protein deficient in Fragile X syndrome and known to regulate translation of mRNAs important for neuronal function and autism. Notably, the FMRP-Top3M-NM-2 interaction is abolished by a disease-associated FMRP mutation, and several human genetic studies link Top3M-NM-2 mutation to schizophrenia and intellectual disability. Top3M-NM-2 binds multiple mRNAs encoded by genes with neuronal functions related to schizophrenia and autism. Expression of one such gene, ptk2/FAK, is reduced in neuromuscular junctions of Top3M-NM-2 mutant flies. Synapse formation is defective in Top3M-NM-2 mutant flies and mice, as observed in FMRP mutant animals. Our findings suggest that Top3M-NM-2 acts as an RNA topoisomerase and works with FMRP to promote expression of mRNAs critical for neurodevelopment and mental health. We have identified Top3M-NM-2 as the first RNA topoisomerase in eukaryotes. To study whether Top3M-NM-2 binds mRNAs in vivo and also to identify its genome-wide RNA targets, we performed HITS-CLIP (high-throughput sequencing of RNAs isolated by crosslinking immunoprecipitation; Licatalosi et al. Nature 456, 464-469, 2008). In this method, proteins are covalently crosslinked with bound RNAs in vivo, thus allowing specific mapping of the sites of interaction of the protein with the RNA. We cultured a HeLa cells stably-expressing HF-Top3M-NM-2 and irradiated the cells with UV to crosslink RNA and proteins in vivo. Following cell lysis, RNA was partially digested using various concentrations of RNase A. The RNA crosslinked to HF-Top3M-NM-2 was then immunoprecipitated with anti-Flag M2 argarose beads (Sigma). As a control, we also performed a mock immunoprecipitation using HeLa cells that do not express HF-Top3M-NM-2. The 3M-bM-^@M-^Y ends of the purified RNAs were ligated to a p32-labeled RNA adapter, fractionated by SDS-PAGE, and transferred to a nitrocellulose membrane. The p32-labeled RNA-Top3M-NM-2 complexes were detected by autoradiography and recovered from the membrane. The complexes were treated with Proteinase K to remove proteins. The RNA was ligated at their 5M-bM-^@M-^Yend to another RNA adaptor, and reverse-transcribed to cDNA. The cDNA obtained was fractionated a denaturing 6% TBE-Urea gel (InVitrogen), amplified by PCR, and subjected to high-throughput sequencing by Genome Analyzer II (Illumina). Sequenced tags were mapped to the human genome (hg18, NCBI/NIH) and to human RefSeq genes using ELAND program (Illumina).
2013-08-04 | E-GEOD-47502 | biostudies-arrayexpress
Project description:FMRP loss-of-function causes Fragile X Syndrome (FXS) and autistic features. FMRP is a polyribosome-associated neuronal RNA-binding protein, suggesting that it plays a key role in regulating neuronal translation, but there has been little consensus regarding either its RNA targets or mechanism of action. Here we use high throughput sequencing of RNAs isolated by crosslinking immunoprecipitation (HITS-CLIP) to identify FMRP interactions with mouse brain polyribosomal mRNAs. FMRP interacts with the coding region of transcripts encoding pre- and postsynaptic proteins, and transcripts implicated in autism spectrum disorders
2013-03-15 | GSE45148 | GEO
Project description:Topoisomerase 3b (Top3b) is the only dual-activity topoisomerase in animals that can change topology for both DNA and RNA, and facilitate transcription on DNA and translation on mRNAs. Top3b mutation has been linked to schizophrenia, autism, epilepsy, and cognitive impairment. However, whether and how Top3b mutations are causal to these disorders remain unclear. Here we show that Top3b knockout mice exhibit behavioral phenotypes related to psychiatric disorders and cognitive impairment, including increased anxiety and fear, abnormal social interactions, impaired context discrimination, and defective spatial learning and memory. In addition, these mice display deficits in adult hippocampal neurogenesis and synaptic plasticity. Notably, the brains of the mutant mice exhibit impaired global neuronal activity-dependent transcription in response to fear conditioning stress, and the affected genes include many that are critical for neuronal functions and mental health. Our data suggest that Top3b is essential for normal brain function in multiple domains, and defective neuronal activity-dependent transcription may be a mechanism by which Top3b deletion causes cognitive impairment and psychiatric disorders.
2020-05-22 | GSE145730 | GEO
Project description:Loss of the neuronal RNA binding protein FMRP causes Fragile X Syndrome (FXS), the most common cause of inherited intellectual disability, yet it is unknown which brain regions and cell types within them contribute to disease pathophysiology. We used conditional tagging of FMRP and CLIP (cTag FMRP CLIP) to examine FMRP targets specifically in CA1 hippocampal neurons, a critical cell type for learning and memory known to have altered synaptic function in FXS. Integrating this data with analysis of ribosome-bound transcripts from the same neuronal population revealed CA1-enriched binding of autism-relevant mRNAs, and unexpected CA1-specific regulation of transcripts encoding circadian proteins.
2020-01-07 | GSE127846 | GEO
Project description:FMRP loss-of-function causes Fragile X Syndrome (FXS) and autistic features. FMRP is a polyribosome-associated neuronal RNA-binding protein, suggesting that it plays a key role in regulating neuronal translation, but there has been little consensus regarding either its RNA targets or mechanism of action. Here we use high throughput sequencing of RNAs isolated by crosslinking immunoprecipitation (HITS-CLIP) to identify FMRP interactions with mouse brain polyribosomal mRNAs. FMRP interacts with the coding region of transcripts encoding pre- and postsynaptic proteins, and transcripts implicated in autism spectrum disorders Polyribosomes were prepared from UV254-crosslinked pooled littermate FVB mouse brains as described in detail in published paper PMID 21784246. Polyribosomes were dissociated under denaturing conditions using two different protocols to disrupt ribonucleoprotein complexes. In most experiments Fmr1-null littermates were used in parallel to confirm FMRP specificity. After mild RNAse treatment to reduce the size of RNA to 60-100 nucleotides, endogenous FMRP was immunoprecipitated with one of two antibody combinations, either mixed monoclonal antibodies 7G1-1 and 2F5, or polyclonal antibody ab17722 (Abcam). The ages of the mice were P11, P13, P14, P15, and P25. In addition, to assess a different neuronal polysome-associated protein, as another control, lysates prepared from two samples, the P11 and P13 mice, were split in half and one half IPed with a human anti-Hu antisera as the neuronal Hu proteins are polysome-associated in brain. In sum, 7 FMRP HITS-CLIP experiments were performed including (1) P14 mouse polysomes prepared by Protocol 1 and IPed with 7G1-1/2F5 (2) P14 mouse polysomes prepared by Protocol 1 and IPed with ab17722 (3) P15 mouse polysomes prepared by Protocol 1 and IPed with 7G1-1/2F5 (4) P25 mouse polysomes prepared by Protocol 1 and IPed with 7G1-1/2F5 (5) P25 mouse polysomes prepared by Protocol 1 and IPed with ab17722 (6) P11 mouse polysomes prepared by Protocol 2 and IPed with ab17722 and (7) P13 mouse polysomes prepared by Protocol 2 and IPed with ab17722. FMRP-bound or Hu-bound RNA tags were cloned and submitted for high throughput sequencing on the Life Science 454 platform (samples 1-5) or the Illumina platform (samples 6 and 7 and the 2 Hu samples processed in parallel with samples 6 and 7). Full details are given in PMID 21784246.
2013-03-15 | E-GEOD-45148 | biostudies-arrayexpress
Project description:Topoisomerase 3β (TOP3B) and TDRD3 form a dual-activity topoisomerase complex that interacts with FMRP and can change the topology of both DNA and RNA. Here, we investigated the post-transcriptional influence of TOP3B and associated proteins on mRNA translation and turnover. First, we discovered that in human HCT116 colon cancer cells, knock-out (KO) of TOP3B had similar effects on mRNA turnover and translation as did TDRD3-KO, while FMRP-KO resulted in rather distinct effects, indicating that TOP3B had stronger coordination with TDRD3 than FMRP in mRNA regulation. Second, we identified TOP3B-bound mRNAs in HCT116 cells; we found that while TOP3B did not directly influence the stability or translation of most TOP3B target mRNAs, it stabilized a subset of target mRNAs but had a more complex effect on translation--enhancing for some mRNAs whereas reducing for others. Interestingly, a point mutation that specifically disrupted TOP3B catalytic activity only partially recapitulated the effects of TOP3B-KO on mRNA stability and translation, suggesting that the impact of TOP3B on target mRNAs is only in part linked to its ability to change topology of mRNAs. Collectively, our data suggest that TOP3B-TDRD3 can regulate mRNA translation and turnover by mechanisms that are dependent and independent of topoisomerase activity.
2022-06-08 | GSE188574 | GEO
Project description:Local translation at the synapse plays key roles in neuron development and activity-dependent synaptic plasticity. mRNAs are translocated from the neuronal soma to the distant synapses as compacted ribonucleoparticles referred to as RNA granules. These contain many RNA-binding proteins, including the Fragile X Mental Retardation Protein (FMRP), the absence of which results in Fragile X Syndrome, the most common inherited form of intellectual disability and the leading genetic cause of autism. Using FMRP as a tracer, we purified a specific population of RNA granules from mouse brain homogenates. Protein composition analyses revealed a strong relationship between polyribosomes and RNA granules. However, the latter have distinct architectural and structural properties, since they are detected as close compact structures as observed by electron microscopy, and converging evidence point to the possibility that these structures emerge from stalled polyribosomes. Time-lapse video microscopy indicated that single granules merge to form cargoes that are transported from the soma to distal locations. Transcriptomic analyses showed that a subset of mRNAs involved in cytoskeleton remodelling and neural development is selectively enriched in RNA granules. One third of the putative mRNA targets described for FMRP appear to be transported in granules and FMRP is more abundant in granules than in polyribosomes. This observation supports a primary role for FMRP in granules biology. Our findings open new avenues for the study of RNA granule dysfunctions in animal models of nervous system disorders, such as Fragile X syndrome. Fragile X syndrome is the most common form of inherited mental retardation affecting approximately 1 female out of 7000 and 1 male out of 4000 worldwide. The syndrome is due to the silencing of a single gene, the Fragile Mental Retardation 1 (FMR1), that codes for the Fragile X mental retardation protein (FMRP). This protein is highly expressed in brain and controls local protein synthesis essential for neuronal development and maturation as well as the formation of neural circuits. Several studies suggest a role for FMRP in the regulation of mRNA transport along axons and dendrites to distant synaptic locations in structures called RNA granules. Here we report the isolation of a particular subpopulation of these structures and the analysis of their architecture and composition in terms of RNA and protein. Also, using time-lapse video microscopy, we monitored granule transport and fusion throughout neuronal processes. These findings open new avenues for the study of RNA transport dysfunctions in animal models of nervous system disorders. The control or reference structure or subcellular fraction are the neuronal polyribosomes while the experimental or test structure or subcellular fraction are the neuronal granules. Three independant replicates were done for each structure. Microarray hybridization was done using a two-color design in full dye-swap.
2016-06-30 | E-GEOD-83835 | biostudies-arrayexpress
Project description:Silencing of FMR1 and loss of its gene product FMRP results in Fragile X Syndrome. FMRP binds brain mRNAs and inhibits polypeptide elongation. Using ribosome profiling of the hippocampus, we find that ribosome footprint levels in Fmr1-deficient tissue mostly reflect changes in RNA abundance. Profiling over a time course of ribosome runoff in wildtype tissue reveals a wide range of ribosome translocation rates; on many mRNAs, the ribosomes are stalled. Sucrose gradient ultracentrifugation of hippocampal slices after ribosome runoff reveals that FMRP co-sediments with stalled ribosomes; and its loss results in decline of ribosome stalling on specific mRNAs. One such mRNA encodes SETD2, a lysine methyltransferase that catalyzes H3K36me3. ChIP-Seq demonstrates that loss of FMRP alters the deployment of this epigenetic mark on chromatin. H3K36me3 is associated with alternative pre-RNA processing, which we find occurs in an FMRP-dependent manner on transcripts linked to neural function and autism spectrum disorders.
2020-03-31 | GSE143330 | GEO
Project description:Silencing of FMR1 and loss of its gene product FMRP results in Fragile X Syndrome. FMRP binds brain mRNAs and inhibits polypeptide elongation. Using ribosome profiling of the hippocampus, we find that ribosome footprint levels in Fmr1-deficient tissue mostly reflect changes in RNA abundance. Profiling over a time course of ribosome runoff in wildtype tissue reveals a wide range of ribosome translocation rates; on many mRNAs, the ribosomes are stalled. Sucrose gradient ultracentrifugation of hippocampal slices after ribosome runoff reveals that FMRP co-sediments with stalled ribosomes; and its loss results in decline of ribosome stalling on specific mRNAs. One such mRNA encodes SETD2, a lysine methyltransferase that catalyzes H3K36me3. ChIP-Seq demonstrates that loss of FMRP alters the deployment of this epigenetic mark on chromatin. H3K36me3 is associated with alternative pre-RNA processing, which we find occurs in an FMRP-dependent manner on transcripts linked to neural function and autism spectrum disorders.
2020-03-31 | GSE143329 | GEO
Project description:Silencing of FMR1 and loss of its gene product FMRP results in Fragile X Syndrome. FMRP binds brain mRNAs and inhibits polypeptide elongation. Using ribosome profiling of the hippocampus, we find that ribosome footprint levels in Fmr1-deficient tissue mostly reflect changes in RNA abundance. Profiling over a time course of ribosome runoff in wildtype tissue reveals a wide range of ribosome translocation rates; on many mRNAs, the ribosomes are stalled. Sucrose gradient ultracentrifugation of hippocampal slices after ribosome runoff reveals that FMRP co-sediments with stalled ribosomes; and its loss results in decline of ribosome stalling on specific mRNAs. One such mRNA encodes SETD2, a lysine methyltransferase that catalyzes H3K36me3. ChIP-Seq demonstrates that loss of FMRP alters the deployment of this epigenetic mark on chromatin. H3K36me3 is associated with alternative pre-RNA processing, which we find occurs in an FMRP-dependent manner on transcripts linked to neural function and autism spectrum disorders.
2020-03-31 | GSE143331 | GEO