Project description:To investigate the locolization between DIS3 and circRNA in fractions form sucrose density gradient centrifugation (SDGC) assay for 293T cells
Project description:We investigated the effect on miRNA expression in Drosophila melanogaster wing imaginal discs following the knockdown of the 3'-5' exoribonuclease Dis3.
Project description:Somatic mutations affecting DIS3, the catalytic component of the RNA exosome, have been found in up to 18% of patients affected by the hematological cancer multiple myeloma. Here we show that DIS3 targets and degrades the pluripotency factor LIN28B. In cancer cells, DIS3 inactivation leads to enhanced LIN28B expression, thus disrupting the let-7 miRNAs tumor suppressor network and ultimately increasing protein levels of crucial oncogenes such as MYC and RAS. DIS3 represents the catalytic component of the exosome. The exosome is required for cell viability and targets several RNA species, including pre-mRNAs, pre-tRNAs, pre-rRNAs, snRNAs and snoRNAs. To gain insight on the macular wiring underlying DIS3 activity in mammalian cells, we comprehensively evaluated expression profiles, including miRNAs, in various cell lines, upon DIS3 knockdown. This series of microarray experiments contains the miRNA expression profiles of independent replicates of RPMI-8226, KMS12-BM multiple myeloma cell lines and HEK-293T cells, knocked-down with a scrambled or hDIS3 sh4 and collected 72 hours after infection. 500 nanograms of total RNA were processed using the FlashTag labeling kit, which uses a tailing reaction followed by ligation of the biotinylated signal molecule to the target RNA sample. The labelled RNA was then hybridized to Affymetrix GeneChip® microRNA arrays v1.0, following the Affymetrix manufacturer's instructions.
Project description:DIS3 is mutated in multiple myeloma (MM), but the mechanism by which oncogenesis occurs specifically in B cell lineage remains to be established. Somatic DIS3 variants have substitutions enriched around its RNB domain, which in a dominant negative way, inactivate or reduce the exoribonucleolytic activity of this enzyme responsible for nuclear RNA degradation. Here using knock-in mice with a clinical Dis3 G766R variant, we demonstrate a B cell-specific mutagenic effect that induces aberrant chromosomal translocations, increasing the incidence of plasmacytoma, a mouse model of early-stage MM. Dis3 G766R -dependent translocations display characteristics typical to aberrant activation-induced deaminase (AID) activity sites. Indeed, analysis of MM clinical samples revealed that in MM driver genes, DIS3 alleles lead to increased AID-dependent DNA lesions. Mechanistically, mutated DIS3 accumulates on chromatin-associated RNA substrates, including aberrant AID action sites, fostering oncogenic chromosomal rearrangements. Translocations occur during immunoglobulin class switch recombination, which otherwise proceeds unaffected both MM and the mouse model. In conclusion, MM DIS3 mutations lead to a gain-of-function phenotype and drive MM development, enhancing driver translocations.
Project description:Multiple myeloma (MM) is a plasma cell neoplasm that remains incurable regardless of the introduction of novel agents. Therefore, it is of necessity to decode the molecular mechanisms of myelomagenesis to identify novel therapeutic strategies. Recent advances in next-generation sequencing technologies have not only reconfirmed the significance of known driver events in MM but also have identified novel genetic alterations in MM. Importantly, mutations of DIS3 genes have been identified in ~10% of MM patients, and loss of heterozygosity at chromosome 13q that leads to deletion of one allele of DIS3 has been observed in ~ 40% of MM patients. However, the roles of DIS3 in hematopoiesis and myelomagenesis remain incompletely understood. Here we show that Dis3 prevents accumulation of DNA damage in hematopoietic cells, thereby supporting hematopoiesis. We also show that loss of Dis3 alone and in combination with c-MAF transgene in GC B cells do not exhibit plasma cell neoplasm in mice.
Project description:Circular RNAs (circRNAs), a noncoding RNA class originating from alternative splicing, are highly abundant in neural tissues and were shown to regulate gene expression e.g. by interacting with microRNAs and RNA-binding proteins. Neuroblastoma is an embryonal neoplasia, which arises from undifferentiated neural crest cells. Here, we aimed to explore, whether circRNAs influence the pathogenesis of high-risk neuroblastoma. We performed whole-transcriptome sequencing of 104 primary neuroblastoma samples of all risk-groups and identified 5,203 unique circRNAs involving 2,302 genes. Candidate circRNA expression did not correlate with host gene expression, indicating independent regulatory mechanisms. circRNAs were significantly downregulated in the MYCN-amplified high-risk tumors. These findings were independently reproduced in a tetracycline-inducible MYCN-overexpression system based on a non MYCN-amplified neuroblastoma cell line, suggesting that MYCN drives this global circRNA repression. We identified the RNA helicase DHX9 as a mediator of this global suppressive effect of MYCN on circRNAs. Comparing our RNA sequencing data with other cancers and controls revealed a circRNA subset specifically upregulated in neuroblastoma that included a circRNA derived from the ARID1A tumor suppressor gene. Specific circARID1A knockdown resulted in reduced proliferation, cell numbers and viability, prompted apoptosis and induced a differentiated phenotype. Neither knockdown, nor overexpression of circARID1A influenced ARID1A mRNA and protein levels significantly. To dissect the potential mode of function, we performed a pulldown assay with subsequent mass spectrometry. We identified the RNA-binding protein KHSRP as an interaction partner that participates in the mechanism of action of circARID1A. In summary, this study highlights an important role of circRNAs in neuroblastoma biology and may establish this RNA class as a future therapeutic target and biomarker.
Project description:Conditional inactivation of DIS3 in spermatocytes impairs meiotic progression and causes defective spermatogenesis in mice. scRNA-seq analysis indicates that DIS3 mutation significantly impairs spermatocytes meiotic progression and dysregulates transcriptome in spermatocytes. We show that DIS3 ribonuclease plays critical roles in male meiotic progression and spermatogenesis in mice.
Project description:Human DIS3 is a nuclear, catalytic subunit of the exosome complex containing exonucleolytic and endonucleolytic active domains. To identify DIS3 targets genome-wide we conducted comprehensive transcriptomic analysis of HEK293 cells producing mutated DIS3 versions and Photoactivatable Ribonucleoside-Enhanced Crosslinking and Immunoprecipitation (PAR-CLIP) experiments. Pervasive transcription products like Promoter Upstream Transcripts (PROMPTs) accumulated robustly in catalytic DIS3 mutants, representing ~8% of PAR-CLIP reads. Importantly, RNAs originating from unannotated genomic regions increased ~2.5 times in double DIS3 mutants, covering ~70% of genome and allowing for discovery of thousands of novel transcripts. The first intron of many pre-mRNAs accumulated in DIS3 mutants indicating a widespread premature RNA polymerase II termination. The short form of NEAT1 lincRNA was overexpressed in DIS3 mutants, leading to increased number of paraspeckles. Moreover, there was a global deregulation of mRNAs in DIS3 double mutant. Finally, snoRNA precursors accumulated, which correlated with a strong PAR-CLIP signal indicating that DIS3 but not RRP6 is a main snoRNA processing enzyme. In aggregate, we demonstrate that DIS3 is a major nucleoplasmic activity responsible for shaping the human transcriptome.