High throughput sequencing for circRNAs and mRNAs in XPO4 knockout NIH/3T3 cell [RNA-seq]
Ontology highlight
ABSTRACT: Numerous RNAs are exported from the nucleus, abnormalities of which lead to cellular complications and diseases. We report the identification of Exportin 4 (XPO4) as a conserved circular RNA (circRNA) exportin. Cellular insufficiency of XPO4 causes nuclear circRNA accumulation, circRNA:DNA (ciR-loop) formation, linear RNA:DNA (liR-loop) buildup, and DNA damage. These results provide insights into the mechanism and biomedical links of circRNA nuclear export.
Project description:Numerous RNAs are exported from the nucleus, abnormalities of which lead to cellular complications and diseases. We report the identification of Exportin 4 (XPO4) as a conserved circular RNA (circRNA) exportin. Cellular insufficiency of XPO4 causes nuclear circRNA accumulation, circRNA:DNA (ciR-loop) formation, linear RNA:DNA (liR-loop) buildup, and DNA damage. These results provide insights into the mechanism and biomedical links of circRNA nuclear export.
Project description:Circular RNAs (circRNAs), which can function as regulators of gene expression, are formed by back-splicing of precursor mRNAs in the nucleus. circRNAs are predominantly localized in the cytoplasm, indicating that they must be exported from the nucleus. Here, we uncover a pathway specific for nuclear export of circular RNA. This pathway requires Ran-GTP, Exportin-2 and IGF2BP1. Enhancing the nuclear Ran-GTP gradient by depletion or chemical inhibition of the major protein exporter, CRM1, selectively increases nuclear export of circRNAs, while reducing the nuclear Ran-GTP gradient selectively blocks circRNA export. Analysis of nuclear circRNA binding proteins reveals that interaction of IGF2BP1 with circRNA is enhanced by Ran-GTP, whereas its interaction with linear RNA is inhibited by Ran-GTP. Depletion or knockout of Exportin-2 specifically inhibits nuclear export of circRNA, while formation of an Exportin-2 circRNA export complex requires Ran-GTP and IGF2BP1. Our findings demonstrate that adaptors such as IGF2BP1 that bind directly to circular RNAs recruit Exportin-2 to export circRNAs in a mechanism analogous to protein export, rather than mRNA export.
Project description:Circular RNAs (circRNAs), which are increasingly being implicated in a variety of functions in normal and cancerous cells1-5, are formed by back-splicing of precursor mRNAs in the nucleus6-10. circRNAs are predom¬inantly localized in the cytoplasm, indicating that they must be exported from the nucleus. Here, we uncover a pathway specific for nuclear export of circular RNA. This pathway requires Ran-GTP, Exportin-2 and IGF2BP1. Enhancing the nuclear Ran-GTP gradient by depletion or chemical inhibition of the major protein exporter, CRM1, selectively increases nuclear export of circRNAs, while reducing the nuclear Ran-GTP gradient selectively blocks circRNA export. Depletion or knockout of Exportin-2 specifically inhibits nuclear export of circRNA. Analysis of nuclear circRNA binding proteins reveals that interaction of IGF2BP1 with circRNA is enhanced by Ran-GTP. Formation of circRNA export complexes in the nucleus is promoted by Ran-GTP through its interactions with IGF2BP1, Exportin-2 and circRNA. Our findings demonstrate that adaptors such as IGF2BP1 that bind directly to circular RNAs recruit Ran-GTP and Exportin-2 to export circRNAs in a mechanism analogous to protein export, rather than mRNA export.
Project description:Aberrant expression of nuclear transporters and altered subcellular localization of their cargo proteins are increasingly recognized as drivers and therapeutic targets of cancer. Here, we report that exportin-6, a nuclear exporter specific for actin/profilin-1, is upregulated in a broad range of cancers and associated with poor prognosis. Exportin-6 loss triggers antitumor effects in breast cancer cells in a profilin-1-dependent fashion. Nuclear profilin-1 interacts with the Super Elongation Complex (SEC), a positive transcriptional regulator of pro-cancer genes including MYC. Exportin-6 loss, by increasing nuclear profilin-1, inhibits SEC-dependent transcription and sensitizes breast cancer cells to inhibition of BET domain proteins. Thus, exportin-6 upregulation is a previously unrecognized cancer addiction that reduces the transcriptional inhibitory and anticancer activities of nuclear profilin-1.
Project description:In lung and prostate adenocarcinomas, neuroendocrine (NE) transformation to an aggressive derivative resembling small cell lung cancer (SCLC) is associated with poor prognosis. We previously described dependency of SCLC on the nuclear transporter exportin 1. Here we explored the role of exportin 1 in NE transformation. We observed upregulated exportin 1 in lung and prostate pre-transformation adenocarcinomas. Exportin 1 was induced upregulated following genetic inactivation of TP53 and RB1 in lung and prostate adenocarcinoma cell lines, accompanied by increased sensitivity to the exportin 1 inhibitor selinexor in vitro. Exportin 1 inhibition prevented NE transformation and extended response to targeted therapies in both lung anddifferent TP53/RB1-inactivated prostate adenocarcinoma xenograft models that acquire NE features upon treatment with the AR inhibitor enzalutamide, and extended response to the EGFR inhibitor osimertinib in a lung cancer transformation patient-derived xenograft (PDX) model exhibiting combined adenocarcinoma/SCLC histology. Ectopic SOX2 expression restored the enzalutamide-promoted NE transformationNE phenotype on adenocarcinoma-to-NE transformation xenograft models despite selinexor treatment. Selinexor sensitized NE-transformed lung and prostate small cell carcinoma PDXs tumors after NE transformation to standard cytotoxics. Together these data nominate exportin 1 inhibition as a novel potential therapeutic approach target to constrain lineage plasticity and prevent or treat NE transformation in lung and prostate adenocarcinoma.
Project description:In lung and prostate adenocarcinomas, neuroendocrine (NE) transformation to an aggressive derivative resembling small cell lung cancer (SCLC) is associated with poor prognosis. We previously described dependency of SCLC on the nuclear transporter exportin 1. Here we explored the role of exportin 1 in NE transformation. We observed upregulated exportin 1 in lung and prostate pre-transformation adenocarcinomas. Exportin 1 was induced upregulated following genetic inactivation of TP53 and RB1 in lung and prostate adenocarcinoma cell lines, accompanied by increased sensitivity to the exportin 1 inhibitor selinexor in vitro. Exportin 1 inhibition prevented NE transformation and extended response to targeted therapies in both lung anddifferent TP53/RB1-inactivated prostate adenocarcinoma xenograft models that acquire NE features upon treatment with the AR inhibitor enzalutamide, and extended response to the EGFR inhibitor osimertinib in a lung cancer transformation patient-derived xenograft (PDX) model exhibiting combined adenocarcinoma/SCLC histology. Ectopic SOX2 expression restored the enzalutamide-promoted NE transformationNE phenotype on adenocarcinoma-to-NE transformation xenograft models despite selinexor treatment. Selinexor sensitized NE-transformed lung and prostate small cell carcinoma PDXs tumors after NE transformation to standard cytotoxics. Together these data nominate exportin 1 inhibition as a novel potential therapeutic approach target to constrain lineage plasticity and prevent or treat NE transformation in lung and prostate adenocarcinoma.
Project description:The pir genes comprise the largest multi-gene family in Plasmodium, with members found in P. vivax, P. knowlesi and the rodent malaria species. Despite comprising up to 5% of the parasite genome, little is known about the functions of the proteins encoded by pir genes. P. chabaudi causes chronic infection in mice, which may be due antigenic variation. In this model, pir genes are called cirs and may be involved in this mechanism allowing evasion of host immune responses. We have annotated the cir repertoire and performed detailed bioinformatic characterization of the encoded CIR proteins. Two major sub-families were identified: A and B, which display different amino acid motifs, and are thus predicted to have undergone functional divergence. The expression of all cirs was analyzed via RNA sequencing and microarray. Up to 40% of cir genes were expressed in the parasite population during infection, including members of both sub-families. Dominant cir transcripts could also be identified. Finally, specific cir genes were expressed at different time points during the blood stages of infection. Together our data characterizing the cir genes and their expression throughout the intra-erythrocytic cycle of development indicate that CIR proteins are likely to be important for parasite survival in the host.
Project description:To analyze the effect of Exportin-5 expression on the MEF cells in cell cycle re-entry phase, we have employed whole genome microarray expression profiling on the MEF cells in cell cycle re-entry phase with and without down regulation of Exportin-5 gene. Mouse MEF cells were transfected with 60nM of siRNA targeting either Exportin-5 or negative control, and incubated for 12 hours. After incubation, cells were starved with DMEM containing 0.2% FCS for 48 hours and re-fed with DMEM containing 20%FCS for 24 hours, along with second siRNA transfection. Two independant expreiments were preformed.
Project description:Circular RNAs (circRNAs) are upregulated during neurogenesis. Where and how circRNAs are localized, and what roles they play during this process have remained elusive. By comparing the nuclear and cytoplasmic circRNAs between H9 cells and H9-derived forebrain neurons (FB), we found a subset of adenosine (A)-rich circRNAs are restricted in H9 nuclei but exported to cytosols upon forebrain neuron differentiation. This differentiation-coupled circRNA subcellular relocation is modulated by the poly(A)-binding protein PABPC1. In the nucleus, newly produced (A)-rich circRNAs are bound by PABPC1 and the nuclear basket protein TPR to prevent their nucleocytoplasmic export. Modulation of (A)-rich motifs in circRNAs remarkably alters their subcellular localization. Enforced (A)-rich circRNAs in cytosols result in mRNA translation suppression. Furthermore, decreased nuclear PABPC1 upon neuronal differentiation enables the export of (A)-rich circRNAs including circRTN4(2,3), which is required for neurite outgrowth. These findings uncover subcellular localization features of circRNAs, linking their processing and function during neurogenesis.
Project description:Circular RNAs (circRNAs) are upregulated during neurogenesis. Where and how circRNAs are localized, and what roles they play during this process have remained elusive. By comparing the nuclear and cytoplasmic circRNAs between H9 cells and H9-derived forebrain neurons (FB), we found a subset of adenosine (A)-rich circRNAs are restricted in H9 nuclei but exported to cytosols upon forebrain neuron differentiation. This differentiation-coupled circRNA subcellular relocation is modulated by the poly(A)-binding protein PABPC1. In the nucleus, newly produced (A)-rich circRNAs are bound by PABPC1 and the nuclear basket protein TPR to prevent their nucleocytoplasmic export. Modulation of (A)-rich motifs in circRNAs remarkably alters their subcellular localization. Enforced (A)-rich circRNAs in cytosols result in mRNA translation suppression. Furthermore, decreased nuclear PABPC1 upon neuronal differentiation enables the export of (A)-rich circRNAs including circRTN4(2,3), which is required for neurite outgrowth. These findings uncover subcellular localization features of circRNAs, linking their processing and function during neurogenesis.