Project description:The nuclear phase of the gene expression pathway culminates in the export of mature mRNAs to the cytoplasm through nuclear pore complexes (NPCs). GANP (Germinal-centre Associated Nuclear Protein) promotes the transfer to NPCs of mRNAs bound to the transport factor NXF1. Here, we demonstrate that GANP, subunit of the TREX-2 mRNA export complex, promotes selective nuclear export of a specific subset of mRNAs whose transport depends on NXF1. Genome-wide gene expression profiling showed that half of the transcripts whose nuclear export was impaired following NXF1 depletion also showed reduced export when GANP was depleted. GANP-dependent transcripts were highly expressed, yet short-lived, and were highly enriched in those encoding central components of the gene expression machinery such as RNA synthesis and processing factors. After injection into Xenopus oocyte nuclei, representative GANP-dependent transcripts showed faster nuclear export kinetics than representative transcripts that were not influenced by GANP depletion. We propose that GANP promotes the nuclear export of specific classes of mRNAs that may facilitate rapid changes in gene expression. We used gene expression profiling to compare the abundance of cytoplasmic RNAs after GANP or NXF1 depletion
Project description:Eukaryotic cells have to prevent the export of unspliced pre-mRNAs until intron removal is completed to avoid the expression of aberrant and potentially harmful proteins. Only mature RNAs associate with the export receptor Mex67 (mammalian TAP) and enter the cytoplasm. The underlying nuclear quality control mechanisms are still unclear. Here we show that two shuttling SR-proteins Gbp2 and Hrb1 are key surveillance factors for the selective export of spliced mRNAs in yeast. Their absence leads to the significant leakage of unspliced pre-mRNAs into the cytoplasm. They bind to pre-mRNAs and the spliceosome during splicing, where they are necessary for the surveillance of splicing and the stable binding of the TRAMP-complex to the spliceosome-bound transcripts. Faulty transcripts are marked for their degradation at the nuclear exosome. On correct mRNAs the SR-proteins recruit Mex67 upon completion of splicing to allow a quality controlled nuclear export. Altogether, these data identify a role for shuttling SR-proteins in mRNA surveillance and nuclear mRNA quality control. 6 samples, i.e. 2 replicates per protein Gbp2, Hrb1 and Npl3
Project description:The nuclear phase of the gene expression pathway culminates in the export of mature mRNAs to the cytoplasm through nuclear pore complexes (NPCs). GANP (Germinal-centre Associated Nuclear Protein) promotes the transfer to NPCs of mRNAs bound to the transport factor NXF1. Here, we demonstrate that GANP, subunit of the TREX-2 mRNA export complex, promotes selective nuclear export of a specific subset of mRNAs whose transport depends on NXF1. Genome-wide gene expression profiling showed that half of the transcripts whose nuclear export was impaired following NXF1 depletion also showed reduced export when GANP was depleted. GANP-dependent transcripts were highly expressed, yet short-lived, and were highly enriched in those encoding central components of the gene expression machinery such as RNA synthesis and processing factors. After injection into Xenopus oocyte nuclei, representative GANP-dependent transcripts showed faster nuclear export kinetics than representative transcripts that were not influenced by GANP depletion. We propose that GANP promotes the nuclear export of specific classes of mRNAs that may facilitate rapid changes in gene expression.
Project description:Eukaryotic cells have to prevent the export of unspliced pre-mRNAs until intron removal is completed to avoid the expression of aberrant and potentially harmful proteins. Only mature RNAs associate with the export receptor Mex67 (mammalian TAP) and enter the cytoplasm. The underlying nuclear quality control mechanisms are still unclear. Here we show that two shuttling SR-proteins Gbp2 and Hrb1 are key surveillance factors for the selective export of spliced mRNAs in yeast. Their absence leads to the significant leakage of unspliced pre-mRNAs into the cytoplasm. They bind to pre-mRNAs and the spliceosome during splicing, where they are necessary for the surveillance of splicing and the stable binding of the TRAMP-complex to the spliceosome-bound transcripts. Faulty transcripts are marked for their degradation at the nuclear exosome. On correct mRNAs the SR-proteins recruit Mex67 upon completion of splicing to allow a quality controlled nuclear export. Altogether, these data identify a role for shuttling SR-proteins in mRNA surveillance and nuclear mRNA quality control.
Project description:Several transcription inhibitors have been developed as cancer therapies. However, they show modest clinical activity highlighting that our understanding of the cellular response to transcriptional inhibition remains incomplete. Here we report that potent inhibitors of transcription not only impact mRNA output, but also markedly impair mRNA transcript localisation and nuclear export. We demonstrate that retention of newly transcribed mRNA in nuclear speckles is an adaptive response to chemically distinct transcriptional inhibitors. Retained transcripts are fully processed and accumulate in proportion to the expression level of the genes from which they emanate. The TREX mRNA export complex plays an integral role in directing nascent transcripts to nuclear speckles where they are bound to NXF1, protected from degradation, and poised for rapid export following re-initiation of transcription. Our findings provide new insights into the crosstalk between transcription and mRNA export, with important implications for drugs aiming to inhibit transcription for therapeutic gain.
Project description:Several transcription inhibitors have been developed as cancer therapies. However, they show modest clinical activity highlighting that our understanding of the cellular response to transcriptional inhibition remains incomplete. Here we report that potent inhibitors of transcription not only impact mRNA output, but also markedly impair mRNA transcript localisation and nuclear export. We demonstrate that retention of newly transcribed mRNA in nuclear speckles is an adaptive response to chemically distinct transcriptional inhibitors. Retained transcripts are fully processed and accumulate in proportion to the expression level of the genes from which they emanate. The TREX mRNA export complex plays an integral role in directing nascent transcripts to nuclear speckles where they are bound to NXF1, protected from degradation, and poised for rapid export following re-initiation of transcription. Our findings provide new insights into the crosstalk between transcription and mRNA export, with important implications for drugs aiming to inhibit transcription for therapeutic gain.
Project description:Several transcription inhibitors have been developed as cancer therapies. However, they show modest clinical activity highlighting that our understanding of the cellular response to transcriptional inhibition remains incomplete. Here we report that potent inhibitors of transcription not only impact mRNA output, but also markedly impair mRNA transcript localisation and nuclear export. We demonstrate that retention of newly transcribed mRNA in nuclear speckles is an adaptive response to chemically distinct transcriptional inhibitors. Retained transcripts are fully processed and accumulate in proportion to the expression level of the genes from which they emanate. The TREX mRNA export complex plays an integral role in directing nascent transcripts to nuclear speckles where they are bound to NXF1, protected from degradation, and poised for rapid export following re-initiation of transcription. Our findings provide new insights into the crosstalk between transcription and mRNA export, with important implications for drugs aiming to inhibit transcription for therapeutic gain.
Project description:Genome-wide mapping of decay factor-mRNA interactions in yeast identifies nutrient responsive transcripts as targets of the deadenylase Ccr4