Project description:Nucleoporins are major constituents of nuclear pore complexes, molecular conglomerates embedded within the nuclear envelope that participate in bidirectional trafficking between nucleus and cytoplasm, chromatin silencing and organization, and transcriptional regulation . This functional vantage point is of utmost importance for fundamental cell processes such as intracellular signaling, cell migration, DNA repair and cell division, all of which can be impaired when the molecular identity of the NE and nuclear pore complex is compromised, as seen in cancer. Here we identify a nucleoporin POM121 as a key regulator of proliferation, tumourigenesis, and survival in chemoresistant prostate cancer. Mechanistically, POM121 regulates nuclear transport of specific survival-conferring transcription factors (MYC and E2F1) and androgen receptor that have been previously linked with advanced stages of prostate cancer. POM121-mediated deregulation of nucleocytoplasmic transport occurs through its interaction with Importin β, which serves as a pharmacological target that decreases tumour growth, sensitizes the tumor cells to standard chemotherapy, and improves survival of patient-derived xenograft mice. These results indicate that nuclear pore complex represents a novel mechanism of chemoresistance, which can be therapeutically targetable in aggressive prostate cancer.
Project description:Embedded in the nuclear envelope, nuclear pore complexes (NPCs) not only regulate nuclear transport, but also interface with both transcriptionally active euchromatin and largely silenced heterochromatin, as well as the boundaries between these regions. It is unclear what functional role NPCs play in establishing or maintaining these distinct chromatin domains. Here we report that the yeast NPC protein Nup170p interacts with specific regions of the genome containing ribosomal protein and subtelomeric genes. At these locations, Nup170p functions to establish normal nucleosome positioning and as a repressor of transcription. We show that the function of Nup170p in subtelomeric gene silencing is linked to its association with the RSC chromatin-remodeling complex and the silencing factor Sir4p, and that the binding of Nup170p and Sir4p to subtelomeric chromatin is cooperative and necessary for the association of telomeres with the nuclear envelope. Our results establish the NPC as an active participant in the formation of peripheral heterochromatin. This SuperSeries is composed of the SubSeries listed below. Refer to individual Series
Project description:Recent evidence suggests that nucleoporins, well known components that control nucleo-cytoplasmic trafficking, have wide-ranging functions in developmental gene regulation that potentially extend beyond their role in nuclear transport. Whether the unexpected role of nuclear pore proteins in transcription regulation, which initially has been described in fungi and flies, also applies to human cells is unknown. Here we show at a genome-wide level that the nuclear pore protein NUP98 associates with developmentally regulated genes active during human embryonic stem cell differentiation. Examination of Nup98 binding using multiple Nup98 antibodies in four cell types, three of which are related by direct lineage.
Project description:Nuclear mRNA export via nuclear pore complexes is an essential step in eukaryotic gene expression. Although factors involved in mRNA transport have been characterized, a comprehensive mechanistic understanding of this process and its regulation is lacking. Here, we use single-RNA imaging in yeast to show that cells use mRNA retention to control mRNA export during stress. We demonstrate that upon glucose withdrawal the essential RNA-binding factor Nab2 forms RNA-dependent condensate-like structures in the nucleus. This coincides with a reduced abundance of the DEAD-box ATPase Dbp5 at the nuclear pore. Depleting Dbp5, and consequently blocking mRNA export, is necessary and sufficient to trigger Nab2 condensation. The state of Nab2 condensation influences the extent of nuclear mRNA accumulation and can be recapitulated in vitro, where Nab2 forms RNA-dependent liquid droplets. We hypothesize that cells use condensation to regulate mRNA export and to control gene expression during stress.
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:Previous BioID experiments targeting the nucleoporin (NUP) NUP158 (PMID: 36410438; PXD031245), as well as NUP110, NUP76, NUP96 (PMID: 39206942; PXD047268)and NUP75, transport factors MEX67 and Ran(PXD055934), indicated that proximity labelling delivers highly specific interactome data in the confined localisation of the nuclear pore, with a labelling radius well below the size of the nuclear pore. The resulting proximity data allowed to assign NUPs and nuclear transport factors to specific subregions of the pore. Here we extended this approach to target NUP98.
Project description:Previous BioID experiments targeting the nucleoporin (NUP) NUP158 (PMID: 36410438; PXD031245), as well as NUP110, NUP76 and NUP96 (PMID: 39206942; PXD047268) indicated that proximity labelling delivers highly specific interactome data in the confined localisation of the nuclear pore, with a labelling radius well below the size of the nuclear pore. The resulting proximity data allowed to assign NUPs and nuclear transport factors to specific subregions of the pore. Here we extended this approach to target NUP75 and transport factors MEX67 and Ran.
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:Nucleoporins (Nups) are a family of proteins best known as the constituent building blocks of nuclear pore complexes (NPCs), the transport channels that mediate nuclear transport. Recent evidence suggest that several Nups have additional roles in controlling the activation and silencing of developmental genes, however, the mechanistic details of these functions remain poorly understood. Here, we show that depletion of Nup153 in mouse embryonic stem cells (mESCs) causes the de-repression of developmental genes and induction of early differentiation. This loss of pluripotency is not associated with defects in global nucleo-cytoplasmic transport activity. Instead, Nup153 binds to the transcriptional start site (TSS) of developmental genes and mediates the recruitment of the polycomb repressive complex 1 (PRC1) to its target loci. Our results reveal a nuclear transport-independent role of Nup153 in maintaining stem cell pluripotency and introduce a role of NPC proteins in mammalian epigenetic gene silencing. RNA-seq, ChIP-Seq, and DamID-Seq for Nup153, Oct4, and key chromatin regulators in mouse ES cells and neural progenitors
Project description:Embedded in the nuclear envelope, nuclear pore complexes (NPCs) not only regulate nuclear transport, but also interface with both transcriptionally active euchromatin and largely silenced heterochromatin, as well as the boundaries between these regions. It is unclear what functional role NPCs play in establishing or maintaining these distinct chromatin domains. Here we report that the yeast NPC protein Nup170p interacts with specific regions of the genome containing ribosomal protein and subtelomeric genes. At these locations, Nup170p functions to establish normal nucleosome positioning and as a repressor of transcription. We show that the function of Nup170p in subtelomeric gene silencing is linked to its association with the RSC chromatin-remodeling complex and the silencing factor Sir4p, and that the binding of Nup170p and Sir4p to subtelomeric chromatin is cooperative and necessary for the association of telomeres with the nuclear envelope. Our results establish the NPC as an active participant in the formation of peripheral heterochromatin. The genome-wide localization profiles of Nup170p and Nup157p were determined by chromatin immunoprecipitation and DNA microarray analysis using agilent whole genome Saccharomyces cerevisiae arrays. In addition, the localization profile of Nup170p was determined in sir4∆ and yku70∆ strains.