Project description:To confirm the lack of expression of most miRNAs in DICER1 knock-out cell lines, we performed miRNA microarray analysis. The purpose of this study is to classify DICER1-dependent Small RNA and independent Small RNA using DICER1 cells using deficient cell lines, and to identify novel small RNA and small RNA processing mechanisms.
Project description:The DICER1 gene is mutated in cancer, including Dicer1 syndrome, a rare tumour predisposition syndrome. Cancer-associated hotspots mutations have been reported in both catalytic domains of Dicer, and are predicted to disrupt miRNA processing activity. To understand these hotspot mutations in cancer development, we have generated cell lines harbouring single amino acid substitutions within either the RNAse IIIa (S1344L) and the RNAse IIIb (D1709N) domains of the endogenous Dicer1 gene. We show that both mutations result in a widespread loss of 5p miRNAs, but, unexpectedly, an increase in 3p passenger strands loading into Ago2. Similarities between both mutants can be explained as the S1344 residue is structurally also part of the RNase IIIb catalytical site. Functionally, we found that changes in the repertoire of miRNAs loaded into Ago2 result in altered gene expression, impacting critical pathways for cancer development, including metastatic potential. Our results indicate that inactivating the processing activity of Dicer does not result in genomic instability. Instead, mutations cause a specific upregulation of human endogenous retrovirus H (HERVH) and 3p miRNAs, which have the potential to be used as markers for Dicer1 syndrome tumours.
Project description:Goal: elucidate transcriptomic changes upon knock-out of components of the FERRY complex Methods: RNA extraction from HeLa wildtype and fy-1, fy-2, fy-4 and fy-5 knock-out celllines and subsequent RNASeq Results: We observed differences in the transcriptome of all four knock-out cell lines Conclusions: In the Analysis we focused on genes that were differentially expressed in all four KO cell lines or upon KO of fy-1 and fy-2.
Project description:To further characterize differential expression of miRNA and mRNA levels in livers of 12 weeks old male Tax1BP1 wildtype and knock-out mice, the untreated mice were sacrificed and miRNA and mRNA levels were determined miRNA was labeled with the Affymetrix FlashTag Biotin HSR RNA Labeling Kit
Project description:Recurrent somatic hotspot mutations of DICER1 appear to be clustered around each of four critical metal binding residues in the RNase IIIB domain of DICER1. This domain is responsible for cleavage of the 3’ end of the 5p-miRNA strand of a pre-mRNA hairpin. To investigate the effects of these cancer-associated “hotspot” mutations we engineered mouse Dicer1-deficient ES cells to express wild-type and an allelic series of the mutant human DICER1 variants. Global miRNA and mRNA profiles from cells carrying the metal binding site mutations were compared to each other and wild-type human DICER1. The miRNA and mRNA profiles generated through the expression of the hotspot mutations were virtually identical, and the DICER1 hotspot mutation carrying cells were distinct from both wild-type and Dicer1-deficient cells. Further, miRNA profiles showed mutant DICER1 results in a dramatic loss in processing of mature 5p-miRNA strands but were still able to create 3p-strand miRNAs. Messenger-RNA profile changes were consistent with the loss of 5p-strand miRNAs and showed enriched expression for predicted targets of the lost 5p derived miRNAs. We therefore conclude that cancer-associated somatic hotspot mutations of DICER1, affecting any one of four metal binding residues in the RNase IIIB domain, are functionally equivalent with respect to miRNA-processing and are hypomorphic alleles, yielding a global loss in processing of mature 5p-strand miRNA. We further propose that this resulting 3p-strand bias in mature miRNA expression likely underpins the oncogenic potential of these hotspot mutations. A total of 28 Affymetrix Mouse Gene ST arrays were done for mRNA expression profiling of various DICER1 mutants (n=14), wildtype controls (n=6), vector only (n=3) and parental cell lines (n=5).
Project description:Recurrent somatic hotspot mutations of DICER1 appear to be clustered around each of four critical metal binding residues in the RNase IIIB domain of DICER1. This domain is responsible for cleavage of the 3’ end of the 5p-miRNA strand of a pre-mRNA hairpin. To investigate the effects of these cancer-associated “hotspot” mutations we engineered mouse Dicer1-deficient ES cells to express wild-type and an allelic series of the mutant human DICER1 variants. Global miRNA and mRNA profiles from cells carrying the metal binding site mutations were compared to each other and wild-type human DICER1. The miRNA and mRNA profiles generated through the expression of the hotspot mutations were virtually identical, and the DICER1 hotspot mutation carrying cells were distinct from both wild-type and Dicer1-deficient cells. Further, miRNA profiles showed mutant DICER1 results in a dramatic loss in processing of mature 5p-miRNA strands but were still able to create 3p-strand miRNAs. Messenger-RNA profile changes were consistent with the loss of 5p-strand miRNAs and showed enriched expression for predicted targets of the lost 5p derived miRNAs. We therefore conclude that cancer-associated somatic hotspot mutations of DICER1, affecting any one of four metal binding residues in the RNase IIIB domain, are functionally equivalent with respect to miRNA-processing and are hypomorphic alleles, yielding a global loss in processing of mature 5p-strand miRNA. We further propose that this resulting 3p-strand bias in mature miRNA expression likely underpins the oncogenic potential of these hotspot mutations.