Project description:Transcription is a major obstacle for replication fork progression and a cause of genome instability. Such instability increases in mutants with a suboptimal assembly of the nascent messenger ribonucleo-protein particle (mRNP), as THO/TREX and the NPC-associated THSC/TREX-2 complex. Here we show that yeast sac3M-bM-^HM-^F and thp1M-bM-^HM-^F cells accumulate genome-wide replication obstacles as determined by the distribution of the Rrm3 helicase. Such obstacles preferentially occur at long and highly expressed genes, to which Sac3 and its interacting partner Thp1 are preferentially bound in wild-type cells. ChIP-chip studies were perfomed with antibodies against Flag-tagged Thp1 and Sac3 proteins in wild-type cells of the yeast S. Cerevisiae, as well as Flag-tagged Rrm3 protein in sac3M-bM-^HM-^F and thp1M-bM-^HM-^F cells that were compared with Rrm3 in wild-type cells from Santos-Pereira et al., 2013 (accession number GSE50185).
Project description:Evidence indicates that transcription and mRNA export are linked processes. The molecular mechanisms of this coordination are not clear however. Sus1 (hENY2) participates in this coordination as part of two protein complexes: SAGA, a transcriptional co-activator and TREX-2 that functions in mRNA biogenesis and export. Here we investigate the coordinated action of SAGA and TREX-2 that is required for gene expression. We demonstrate that the TREX-2/proteasomal subunit Sem1, influences Sus1 role in mRNA export and TREX-2 stability. Wide analyses of gene expression reveal that Sem1 and Sus1 have also overlapping functions in transcription. In the absence of Sem1, expression of some SAGA-dependent genes is compromised with a concomitant decrease of RNAP II recruitment to promoters. Notably, ChIP experiments revealed a distinct dependency for SAGA subunits recruitment on Sem1. While absence of Sem1 lowers Ada2 and Taf9 recruitment to GAL1 promoter upon activation, association of the deubiquitylation module remains intact. However, H2B deubiquitylation activity is dramatically decreased. These results unveil a new role for Sem1 in influencing activation of SAGA-dependent H2B deubiquitylation likely mediated by stabilization of TREX-2 complex and SAGA modular assembly. Our work gives insights in how modular architecture of SAGA is determinant for its function in gene expression.
Project description:Nuclear pore complexes (NPCs) influence gene expression besides their established function in nuclear transport. The TREX-2 complex localizes to the NPC basket and affects gene-NPC interactions, transcription and mRNA export. How TREX-2 regulates the gene expression machinery is unknown. Here, we show that TREX-2 interacts with the Mediator complex, an essential regulator of RNA Polymerase (Pol) II. Structural and biochemical studies identify a conserved region on TREX-2, which directly binds the Mediator Med31/Med7N submodule. TREX-2 regulates assembly of Mediator with its Cdk8 kinase and is required for recruitment and site-specific phosphorylation of Pol II. Transcriptome and phenotypic profiling confirm that TREX-2 and Med31 are functionally interdependent. TREX-2 additionally uses its Mediator-interacting surface to regulate mRNA export suggesting a mechanism for coupling transcription initiation and early steps of mRNA processing at the Mediator level. In sum, we provide insight into how NPC-associated adaptor complexes can access the core transcription machinery. RNAseq was performed from WT, sac3∆, cdk8∆ and Sac3 R288D mutant cells. For each strain triplicates were analyzed. WT strain was sac3∆ transformed with pRS315 SAC3 WT
Project description:N6-methyladenosine (m6A) is the most abundant internal modification of eukaryotic mRNA. This modification has previously been shown to alter the export kinetics for mRNAs though the molecular details surrounding this phenomenon remain poorly understood. Here we show that the m6A complex (WTAP, KIAA1429, METTL3/14) drives recruitment of the TREX mRNA export complex onto m6A modified mRNAs and this process is essential for the efficient export of certain mRNAs. Depletion of the core m6A complex leads to loss of TREX from mRNAs which undergo the m6A modification. We show that TREX stimulates recruitment of the m6A reader protein YTHDC1 to the mRNP and the m6A complex influences the interaction of TREX with YTHDC1. We suggest that m6A acts as a surrogate for other TREX recruitment mechanisms such as splicing and 5’ capping, in long internal and final exons which may otherwise be devoid of this essential complex for mRNA export.
Project description:Evidence indicates that transcription and mRNA export are linked processes. The molecular mechanisms of this coordination are not clear however. Sus1 (hENY2) participates in this coordination as part of two protein complexes: SAGA, a transcriptional co-activator and TREX-2 that functions in mRNA biogenesis and export. Here we investigate the coordinated action of SAGA and TREX-2 that is required for gene expression. We demonstrate that the TREX-2/proteasomal subunit Sem1, influences Sus1 role in mRNA export and TREX-2 stability. Wide analyses of gene expression reveal that Sem1 and Sus1 have also overlapping functions in transcription. In the absence of Sem1, expression of some SAGA-dependent genes is compromised with a concomitant decrease of RNAP II recruitment to promoters. Notably, ChIP experiments revealed a distinct dependency for SAGA subunits recruitment on Sem1. While absence of Sem1 lowers Ada2 and Taf9 recruitment to GAL1 promoter upon activation, association of the deubiquitylation module remains intact. However, H2B deubiquitylation activity is dramatically decreased. These results unveil a new role for Sem1 in influencing activation of SAGA-dependent H2B deubiquitylation likely mediated by stabilization of TREX-2 complex and SAGA modular assembly. Our work gives insights in how modular architecture of SAGA is determinant for its function in gene expression. Two channel microarrays were used. RNA isolated from a large amount of wt yeast from a single culture was used as a common reference. This common reference was used in one of the channels for each hybridization and used in the statistical analysis to obtain an average expression-profile for each deletion mutant relative to the wt. Two independent cultures were hybridized on two separate microarrays. For the first hybridization the Cy5 (red) labeled cRNA from the deletion mutant is hybridized together with the Cy3 (green) labeled cRNA from the common reference. For the replicate hybridization, the labels are swapped. Each gene is represented twice on the microarray, resulting in four measurements per mutant. Using the Erlenmeyer growth protocol up to five deletion strains were grown on a single day. In the tecan platereader, up to eleven deletion strains could be grown on a single day. Wt cultures were grown parallel to the deletion mutants to assess day-to-day variance.
Project description:Nuclear pore complexes (NPCs) influence gene expression besides their established function in nuclear transport. The TREX-2 complex localizes to the NPC basket and affects gene-NPC interactions, transcription and mRNA export. How TREX-2 regulates the gene expression machinery is unknown. Here, we show that TREX-2 interacts with the Mediator complex, an essential regulator of RNA Polymerase (Pol) II. Structural and biochemical studies identify a conserved region on TREX-2, which directly binds the Mediator Med31/Med7N submodule. TREX-2 regulates assembly of Mediator with its Cdk8 kinase and is required for recruitment and site-specific phosphorylation of Pol II. Transcriptome and phenotypic profiling confirm that TREX-2 and Med31 are functionally interdependent. TREX-2 additionally uses its Mediator-interacting surface to regulate mRNA export suggesting a mechanism for coupling transcription initiation and early steps of mRNA processing at the Mediator level. In sum, we provide insight into how NPC-associated adaptor complexes can access the core transcription machinery.
Project description:A central function in linking RNA polymerase II transcription and pre-mRNA processing with mRNA export is executed by the transcription and export (TREX) complex. TREX consists of a hexameric core termed THO that associates with various combinations of additional proteins giving rise to alternative versions of TREX. Cell fractionation in combination with transcript profiling demonstrated that THO5 a subunit of the THO complex is required for export of a subset of mRNAs .
Project description:In human somatic cells, ZC3H11A has been recently characterized as an RNA-export protein that functions through its interaction with TREX complex proteins. In order to identify its interacting partners in embryonic cells, and to investigate if ZC3H11A maintains its association with the TREX complex in mouse embryonic stem cells (mESCs), we have performed co-immunoprecipitations (co-IPs) using anti-ZC3H11A, anti-THOC2 and anti-IgG antibodies followed by mass spectrometry (MS) analyses. Statistical analyses of detected MS intensities from the biological replicates (n=4) have revealed a number of proteins with statistically significant interaction with ZC3H11A and THOC2. Results in xlsx format contain the log-fold change in protein intensities in the ZC3H11A co-IP relative to the IgG co-IP and is presented along with the adjusted P-values.