Project description:Nuclear export of mRNA is essential for eukaryotic cells to establish the flow of genetic information in the nucleus to protein synthesis in the cytoplasm. This transport process is highly regulated to ensure efficient and accurate gene expression. Viruses are well known for their ability to manipulate host gene expression. Here, we report that ORF10 of Kaposi’s sarcoma associated herpesvirus (KSHV), a nuclear DNA virus, inhibits mRNA export in a transcript-selective manner to control cellular gene expression. This export inhibitory effect of ORF10 requires the interaction with an RNA export factor, Rae1. Genome-wide analysis by RNA sequencing revealed the subset of cellular mRNAs whose nuclear export is blocked by ORF10. The 3’ untranslated regions (3’ UTRs) of ORF10-targeted transcripts confer their sensitivity to nuclear export inhibition by ORF10. In the context of KSHV replication, the interaction of ORF10 with Rae1 is important for the virus to express viral genes and produce infectious virions. Our results suggest that a nuclear replicating DNA virus can selectively interfere with RNA export through Rae1 to restrict host gene expression for optimal viral replication.
Project description:Analysis of cellular response to DHODH inhibition at gene expression level. The NS1 protein of influenza virus is a major virulence factor essential for virus replication as it re-directs the host cell to promote viral protein expression. NS1 inhibits cellular mRNA processing and export, down-regulating host gene expression and enhancing viral gene expression. We report here the identification of a non-toxic quinoline carboxylic acid that reverts the inhibition of mRNA nuclear export by NS1, in the absence or presence of virus. This quinoline carboxylic acid directly inhibited dihydroorotate dehydrogenase (DHODH), a host enzyme required for *de novo* pyrimidine biosynthesis, and partially reduced pyrimidine levels. This effect induced NXF1 expression, which promoted mRNA nuclear export in the presence of NS1. The release of NS1-mediated mRNA export block by DHODH inhibition also occurred in the presence of VSV M protein, another viral inhibitor of mRNA export. This reversal of mRNA export block allowed expression of antiviral factors. Thus, pyrimidines play a necessary role in the inhibition of mRNA nuclear export by virulence factors. Total RNA obtained from HBEC cells subjected to compound 1/compound 1-14 treatment compared to DMSO treatment.
Project description:Analysis of cellular response to DHODH inhibition at gene expression level. The NS1 protein of influenza virus is a major virulence factor essential for virus replication as it re-directs the host cell to promote viral protein expression. NS1 inhibits cellular mRNA processing and export, down-regulating host gene expression and enhancing viral gene expression. We report here the identification of a non-toxic quinoline carboxylic acid that reverts the inhibition of mRNA nuclear export by NS1, in the absence or presence of virus. This quinoline carboxylic acid directly inhibited dihydroorotate dehydrogenase (DHODH), a host enzyme required for *de novo* pyrimidine biosynthesis, and partially reduced pyrimidine levels. This effect induced NXF1 expression, which promoted mRNA nuclear export in the presence of NS1. The release of NS1-mediated mRNA export block by DHODH inhibition also occurred in the presence of VSV M protein, another viral inhibitor of mRNA export. This reversal of mRNA export block allowed expression of antiviral factors. Thus, pyrimidines play a necessary role in the inhibition of mRNA nuclear export by virulence factors. Total RNA obtained from HBEC cells subjected to 3 hours compound 1 treatment compared to DMSO treatment.
Project description:Analysis of cellular response to DHODH inhibition at gene expression and nuclear/cytoplasmic distribution level. The NS1 protein of influenza virus is a major virulence factor essential for virus replication as it re-directs the host cell to promote viral protein expression. NS1 inhibits cellular mRNA processing and export, down-regulating host gene expression and enhancing viral gene expression. We report here the identification of a non-toxic quinoline carboxylic acid that reverts the inhibition of mRNA nuclear export by NS1, in the absence or presence of virus. This quinoline carboxylic acid directly inhibited dihydroorotate dehydrogenase (DHODH), a host enzyme required for *de novo* pyrimidine biosynthesis, and partially reduced pyrimidine levels. This effect induced NXF1 expression, which promoted mRNA nuclear export in the presence of NS1. The release of NS1-mediated mRNA export block by DHODH inhibition also occurred in the presence of VSV M protein, another viral inhibitor of mRNA export. This reversal of mRNA export block allowed expression of antiviral factors. Thus, pyrimidines play a necessary role in the inhibition of mRNA nuclear export by virulence factors. Five million 293T cells were non-transfected or transfected with 6ug of pEGFPN3-M-GFP for 16h. Then, cells were untreated or treated with compound 1(5uM) for 24h. RNA from total cell extracts or from nuclear or cytoplasmic fractions were obtained
Project description:Analysis of cellular response to DHODH inhibition at gene expression and nuclear/cytoplasmic distribution level. The NS1 protein of influenza virus is a major virulence factor essential for virus replication as it re-directs the host cell to promote viral protein expression. NS1 inhibits cellular mRNA processing and export, down-regulating host gene expression and enhancing viral gene expression. We report here the identification of a non-toxic quinoline carboxylic acid that reverts the inhibition of mRNA nuclear export by NS1, in the absence or presence of virus. This quinoline carboxylic acid directly inhibited dihydroorotate dehydrogenase (DHODH), a host enzyme required for *de novo* pyrimidine biosynthesis, and partially reduced pyrimidine levels. This effect induced NXF1 expression, which promoted mRNA nuclear export in the presence of NS1. The release of NS1-mediated mRNA export block by DHODH inhibition also occurred in the presence of VSV M protein, another viral inhibitor of mRNA export. This reversal of mRNA export block allowed expression of antiviral factors. Thus, pyrimidines play a necessary role in the inhibition of mRNA nuclear export by virulence factors. Five million 293T cells were non-transfected or transfected with 6ug of pCAGGS-NS1 for 16h. Then, cells were untreated or treated with compound 1(5uM) for 24h. RNA from total cell extracts or from nuclear or cytoplasmic fractions were obtained
Project description:Analysis of cellular response to DHODH inhibition at gene expression and nuclear/cytoplasmic distribution level. The NS1 protein of influenza virus is a major virulence factor essential for virus replication as it re-directs the host cell to promote viral protein expression. NS1 inhibits cellular mRNA processing and export, down-regulating host gene expression and enhancing viral gene expression. We report here the identification of a non-toxic quinoline carboxylic acid that reverts the inhibition of mRNA nuclear export by NS1, in the absence or presence of virus. This quinoline carboxylic acid directly inhibited dihydroorotate dehydrogenase (DHODH), a host enzyme required for *de novo* pyrimidine biosynthesis, and partially reduced pyrimidine levels. This effect induced NXF1 expression, which promoted mRNA nuclear export in the presence of NS1. The release of NS1-mediated mRNA export block by DHODH inhibition also occurred in the presence of VSV M protein, another viral inhibitor of mRNA export. This reversal of mRNA export block allowed expression of antiviral factors. Thus, pyrimidines play a necessary role in the inhibition of mRNA nuclear export by virulence factors. Five million 293T cells were non-transfected or transfected with 6ug of pCAGGS-NS1 for 16h. Then, cells were untreated or treated with compound 1(5uM) for 24h. RNA from total cell extracts or from nuclear or cytoplasmic fractions were obtained
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:Analysis of cellular response to DHODH inhibition at gene expression and nuclear/cytoplasmic distribution level. The NS1 protein of influenza virus is a major virulence factor essential for virus replication as it re-directs the host cell to promote viral protein expression. NS1 inhibits cellular mRNA processing and export, down-regulating host gene expression and enhancing viral gene expression. We report here the identification of a non-toxic quinoline carboxylic acid that reverts the inhibition of mRNA nuclear export by NS1, in the absence or presence of virus. This quinoline carboxylic acid directly inhibited dihydroorotate dehydrogenase (DHODH), a host enzyme required for *de novo* pyrimidine biosynthesis, and partially reduced pyrimidine levels. This effect induced NXF1 expression, which promoted mRNA nuclear export in the presence of NS1. The release of NS1-mediated mRNA export block by DHODH inhibition also occurred in the presence of VSV M protein, another viral inhibitor of mRNA export. This reversal of mRNA export block allowed expression of antiviral factors. Thus, pyrimidines play a necessary role in the inhibition of mRNA nuclear export by virulence factors.
Project description:Analysis of cellular response to DHODH inhibition at gene expression and nuclear/cytoplasmic distribution level. The NS1 protein of influenza virus is a major virulence factor essential for virus replication as it re-directs the host cell to promote viral protein expression. NS1 inhibits cellular mRNA processing and export, down-regulating host gene expression and enhancing viral gene expression. We report here the identification of a non-toxic quinoline carboxylic acid that reverts the inhibition of mRNA nuclear export by NS1, in the absence or presence of virus. This quinoline carboxylic acid directly inhibited dihydroorotate dehydrogenase (DHODH), a host enzyme required for *de novo* pyrimidine biosynthesis, and partially reduced pyrimidine levels. This effect induced NXF1 expression, which promoted mRNA nuclear export in the presence of NS1. The release of NS1-mediated mRNA export block by DHODH inhibition also occurred in the presence of VSV M protein, another viral inhibitor of mRNA export. This reversal of mRNA export block allowed expression of antiviral factors. Thus, pyrimidines play a necessary role in the inhibition of mRNA nuclear export by virulence factors.
Project description:Analysis of cellular response to DHODH inhibition at gene expression and nuclear/cytoplasmic distribution level. The NS1 protein of influenza virus is a major virulence factor essential for virus replication as it re-directs the host cell to promote viral protein expression. NS1 inhibits cellular mRNA processing and export, down-regulating host gene expression and enhancing viral gene expression. We report here the identification of a non-toxic quinoline carboxylic acid that reverts the inhibition of mRNA nuclear export by NS1, in the absence or presence of virus. This quinoline carboxylic acid directly inhibited dihydroorotate dehydrogenase (DHODH), a host enzyme required for *de novo* pyrimidine biosynthesis, and partially reduced pyrimidine levels. This effect induced NXF1 expression, which promoted mRNA nuclear export in the presence of NS1. The release of NS1-mediated mRNA export block by DHODH inhibition also occurred in the presence of VSV M protein, another viral inhibitor of mRNA export. This reversal of mRNA export block allowed expression of antiviral factors. Thus, pyrimidines play a necessary role in the inhibition of mRNA nuclear export by virulence factors.