Project description:While nuclear pore proteins mediate nucleo-cytoplasmic transport, they can have important roles in other activities such as transcription, chromatin organization, and cell cycle regulation. The fission yeast nuclear pore protein nup211 localizes to the nuclear basket and is essential for cell viability. Nup211 is important for RNA quality control and the nuclear export of polyadenylated RNAs. Interestingly, several nup211 orthologs have also been shown to regulate transcription at the chromatin level. Although nup211 preferentially associates with heterochromatin, it is unclear whether it modulates transcription. To further investigate the functions of nup211, we constructed a strain in which nup211 expression can be reduced through the addition of thiamine to the growth medium (nup211-so) and examined how cells were affected when nup211 protein was reduced. Down-regulation of nup211 led to severe defects in cell cycle regulation, including septation and cytokinesis. Using RNA-Seq and RT-qPCR, we revealed that loss of nup211 significantly altered global gene expression. Our findings suggest a new role for nup211 in regulating the transcriptome.
Project description:Nuclear pores are essential pathways for nuclear-cytoplasmic transport of molecules. Whether and how cells change nuclear pores to alter nuclear transport and cellular function is unknown. Here, we show that heart muscle cells (cardiomyocytes) undergo a 63% decrease in nuclear pore numbers during differentiation, which alters their response to extracellular signals. This maturation-associated decline in nuclear pore numbers per nucleus is associated with lower nuclear levels and import of Mitogen-activated Protein Kinase (MAPK) signaling proteins. Experimental reduction of nuclear pore numbers decreased nuclear import of MAPK signaling proteins. In a mouse model of high blood pressure, reduction of cardiomyocyte nuclear pore numbers reduced adverse heart remodeling and gene regulation, which reduced progression to lethal heart failure. The observed decrease in nuclear pore numbers in cardiomyocyte differentiation and resulting functional changes suggest a paradigm by which terminally differentiated cells could permanently alter their handling of information flux across the nuclear envelope and, with that, their behavior.
Project description:In budding yeast, Set2 catalyzes di- and trimethylation of H3K36 (H3K36me2 and H3K36me3) via an interaction between its SRI domain and C-terminal repeats of RNA polymerase II (Pol2) phosphorylated at Ser2 and Ser5 (CTD-S2,5-P). H3K36me2 recruits the Rpd3S histone deacetylase complex to repress cryptic transcription from transcribed regions. In fission yeast, Set2 is also responsible for H3K36 methylation, which represses a subset of RNAs including heterochromatic and subtelomeric RNAs, at least in part via recruitment of Clr6 complex II, a homolog of Rpd3S. Here, we show that CTD-S2P–dependent interaction of fission yeast Set2 with Pol2 via the SRI domain is required for formation of H3K36me3, but not H3K36me2. H3K36me3 silenced heterochromatic and subtelomeric transcripts through post-transcriptional and transcriptional mechanisms, respectively, whereas H3K36me2 did not. Clr6 complex II appeared not to be responsible for heterochromatic silencing. Our results demonstrate that H3K36 methylation has multiple outputs in fission yeast; these findings provide insight into the multiple roles of H3K36 methylation in metazoans, which have different enzymes for synthesis of H3K36me1/2 and H3K36me3.
Project description:In budding yeast, Set2 catalyzes di- and trimethylation of H3K36 (H3K36me2 and H3K36me3) via an interaction between its SRI domain and C-terminal repeats of RNA polymerase II (Pol2) phosphorylated at Ser2 and Ser5 (CTD-S2,5-P). H3K36me2 recruits the Rpd3S histone deacetylase complex to repress cryptic transcription from transcribed regions. In fission yeast, Set2 is also responsible for H3K36 methylation, which represses a subset of RNAs including heterochromatic and subtelomeric RNAs, at least in part via recruitment of Clr6 complex II, a homolog of Rpd3S. Here, we show that CTD-S2Pâdependent interaction of fission yeast Set2 with Pol2 via the SRI domain is required for formation of H3K36me3, but not H3K36me2. H3K36me3 silenced heterochromatic and subtelomeric transcripts through post-transcriptional and transcriptional mechanisms, respectively, whereas H3K36me2 did not. Clr6 complex II appeared not to be responsible for heterochromatic silencing. Our results demonstrate that H3K36 methylation has multiple outputs in fission yeast; these findings provide insight into the multiple roles of H3K36 methylation in metazoans, which have different enzymes for synthesis of H3K36me1/2 and H3K36me3. Gene expression profile at exponentially-growing phase.in the fission yeast deletion mutants of set2.
Project description:Using phosphoproteomics and time-lapse fluorescence microscopy, we report that NPCs nuclear pore complexes (NPCs) undergo two distinct modularity events for the nucleoporins Nup60 and Nup2 during budding yeast meiosis: partial and full nuclear basket detachment.
Project description:Nuclear pores associate with active protein-coding genes in yeast and have been implicated in transcriptional regulation. Here, we show that in addition to transcriptional regulation, key components of C. elegans nuclear pores are required for processing of a subset of small nucleolar RNAs (snoRNAs) and tRNAs transcribed by RNA Polymerase (Pol) III. Chromatin immunoprecipitation of NPP-13 and NPP-3, two integral nuclear pore components, and importin-M-CM-^_ IMB-1, provides strong evidence that this requirement is direct. All three proteins associate specifically with tRNA and snoRNA genes undergoing Pol III transcription. These pore components bind immediately downstream of the Pol III pre-initiation complex, but are not required for Pol III recruitment. Instead, NPP-13 is required for cleavage of tRNA and snoRNA precursors into mature RNAs, whereas Pol II transcript processing occurs normally. Our data suggest that integral nuclear pore proteins act to coordinate transcription and processing of Pol III transcripts in C. elegans. Genome-wide ChIP-seq and ChIP-chip were performed in mixed-stage C. elegans embryos for nuclear pore proteins NPP-13, NPP-3, IMB-1 and chromatin proteins Pol III (RPC-1), TBP-1, TFC-1 (SFC-1), TFC-4 (TAG-315), and Pol II (AMA-1). For RPC-1 and TBP-1 ChIP-seq, embryos depleted for NPP-13 were also used. Total RNAs from wild-type, NPP-13 RNAi, and IMB-1 RNAi embryos were analyzed by RNA-seq.
Project description:Nuclear pores associate with active protein-coding genes in yeast and have been implicated in transcriptional regulation. Here, we show that in addition to transcriptional regulation, key components of C. elegans nuclear pores are required for processing of a subset of small nucleolar RNAs (snoRNAs) and tRNAs transcribed by RNA Polymerase (Pol) III. Chromatin immunoprecipitation of NPP-13 and NPP-3, two integral nuclear pore components, and importin-M-CM-^_ IMB-1, provides strong evidence that this requirement is direct. All three proteins associate specifically with tRNA and snoRNA genes undergoing Pol III transcription. These pore components bind immediately downstream of the Pol III pre-initiation complex, but are not required for Pol III recruitment. Instead, NPP-13 is required for cleavage of tRNA and snoRNA precursors into mature RNAs, whereas Pol II transcript processing occurs normally. Our data suggest that integral nuclear pore proteins act to coordinate transcription and processing of Pol III transcripts in C. elegans. Genome-wide ChIP-seq and ChIP-chip were performed in mixed-stage C. elegans embryos for nuclear pore proteins NPP-13, NPP-3, IMB-1 and chromatin proteins Pol III (RPC-1), TBP-1, TFC-1 (SFC-1), TFC-4 (TAG-315), and Pol II (AMA-1). For RPC-1 and TBP-1 ChIP-seq, embryos depleted for NPP-13 were also used. Total RNAs from wild-type, NPP-13 RNAi, and IMB-1 RNAi embryos were analyzed by RNA-seq.