Targeting nuclear pore protein, NUP210, reduces metastasis through heterochromatin-mediated silencing of mechanosensitive genes
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PROVIDER: PRJNA610899 | ENA |
REPOSITORIES: ENA
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Project description:Mechanical signals from the extracellular microenvironment have been shown to promote tumor and metastasis progression. It remains unclear how these signals are transmitted to the nucleus to regulate gene expression necessary for metastatic progression. In a genome-wide screen for metastasis-associated polymorphism in the non-coding regulatory region of the genome, we found NUP210, a nuclear pore complex protein as a metastasis susceptibility gene and a cellular mechanosensor. Depletion of NUP210 in metastatic cancer cells significantly reduces lung metastasis in mouse orthotopic transplantation models. Mechanistically, NUP210 interacts with histone H3.1/3.2 (preferentially enriched at the poised/bivalent gene promoters) at the nuclear periphery. To investigate how NUP210 regulates metastasis, we performed combined ChIP-seq and RNA-seq analysis to identify the NUP210-dependent downstream signaling pathways necessary for metastatic progression. Interestingly, RNA-seq analysis revealed that the loss of NUP210 in cancer cells significantly decreased the expression of mechanosensitive, cell adhesion/migration-related pro-metastatic genes. ChIP-seq analysis of H3K4me3 (transcriptional activation mark) and H3K27me3 (transcriptionally repressive, heterochromatin mark) in NUP210 WT/KO cells revealed that NUP210 loss resulted in increased heterochromatinization of mechanosensitive, cell migration-related genes associated at the nuclear periphery. Our results provide a new insight into the role of nuclear pore protein in regulating cellular mechanosensation and metastasis.
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Project description:The repression of transposons by the Piwi-interacting RNA (piRNA) pathway is essential to protect animal germ cells. In Drosophila ovaries, Panoramix (Panx) enforces transcriptional silencing by binding to the target-engaged Piwi-piRNA complex, although the precise mechanisms by which this occurs remain elusive. Here, we show that Panx functions together with a germline specific paralogue of a nuclear export factor, dNxf2, and its cofactor dNxt1 (p15), as a ternary complex to suppress transposon expression. Similar to Panx, dNxf2 is essential for animal fertility. Structural and functional analyses demonstrate that dNxf2 binds Panx via its UBA domain, which plays an important role in transposon silencing. Unexpectedly, dNxf2 interacts directly with dNxf1 (TAP), a general nuclear export factor. As a result, dNxf2 prevents dNxf1 from binding to the FG repeats of the nuclear pore complex, a process required for proper RNA export. Transient tethering of dNxf2 to nascent transcripts leads to their nuclear retention. Thus, dNxf2 functions in a Pandas (Panoramix dNxf2 dependent TAP/p15 silencing) complex, which counteracts the canonical RNA exporting machinery and restricts transposons to the nuclear peripheries. Our findings may have broader implications for understanding how RNA metabolism regulates epigenetic gene silencing and heterochromatin formation.
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Project description:WIP1 phosphatase is emerging as an important regulator of tumorigenesis, but no unifying mechanistic network has been proposed. Here we found that WIP1 plays a key role in the transcriptional regulation of heterochromatin-associated DNA sequences in germ-line and cancer cells. WIP1 was required for epigenetic remodeling of repetitive DNA elements within the heterochromatin, including L1 LINE retrotransposons. Mechanistically, WIP1regulated an ATM-dependent increase in BRCA1 occupancy on L1 LINEs, resulting in closed chromatin without ubiquitination of histone H2A. This mechanism appeared to be dependent on the ability of BRCA1 to bind the heterochromatin protein HP1, the recruitment of DNA methyltransferases, and subsequent DNA methylation. Attenuation of ATM, in turn, reversed heterochromatin methylation in both germ-line and cancer cells. DNA methylation plays a central role in the generation of mutations in human tumors and we found that WIP1 levels strongly correlated with C-to-T substitutions and a total mutation load in primary breast cancers. We propose that WIP1 plays an important role in the regulation of DNA methylation and global heterochromatin silencing, and thus is critical in maintaining genome integrity during development and in cancer. Total RNA was extracted from control spermatids, Wip1-/- and Wip1-/- Atm+/- spermatids. The final cRNA samples were hybridized in triplicates to Illumina Mouse WG-6 v2.0 Expression arrays.
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Project description:Abstract: In the yeast S. pombe, multiple chromatin-modifying enzymes are required for heterochromatin formation, yet how their actions alter chromatin structure to block access to DNAby the transcriptional machinery is unknown. We constructed high-resolution nucleosome occupancy maps of heterochromatic regions in wild-type strains and in mutants lacking the H3K9 methyltransferase Clr4 or one of the two activities of the silencing effector complex SHREC. Fourier analysis reveals that these enzymes do not increase the regularity of nucleosome spacing. Rather, their principal effect was to induce the elimination of nucleosome-free regions (NFRs). Both NFRs associated with transcription initiation sites as well as those not associated with promoters are affected. As in S. cerevisiae, repressed genes in euchromatin retain their NFRs. Thus, NFR elimination cannot be explained as a secondary consequence of repression. The maps also show that TFIIIC boundary elements have NFRs resistant to silencing, suggesting a potential role in preventing lateral spread of heterochromatin. NFR elimination offers a mechanism by which heterochromatin restricts access of the transcriptional machinery to DNA. Nucleosome positions in either heterochromatin or euchromatin were mapped in various mutants to determine whether chromatin structure is altered upon heterochromatic silencing. Eight strains were assayed for nucleosome positioning in heterochromatin while two strains were assayed for nucleosome positioning in euchromatin. Two biological replicates were assayed for each strain. No dye swaps were done. RNA transcripts were also mapped using the heterochromatin tiling arrays to determine where RNA transcripts accumulate in heterochromatin. Three strains were assayed for transcripts in heterochromatin by hybridizing cy5-labeled cDNA created from total RNA against cy3-labeled cDNA created from RNA synthesized from sonicated genomic DNA. Two biological replicates were assayed for each strain.
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