Project description:Wilms tumor (nephroblastoma) is a pediatric kidney tumor that arises from renal progenitor cells. Since the blastemal type is associated with adverse prognosis, we characterized such Wilms tumors by exome and transcriptome analysis. We detected novel, recurrent somatic mutations affecting the SIX1/2 – SALL1 pathway implicated in kidney development, the DROSHA/DGCR8 microprocessor genes as well as alterations in MYCN and TP53, the latter being strongly associated with dismal outcome. The DROSHA mutations impair the RNase III domains, while DGCR8 exhibits stereotypic E518K mutations in the RNA binding domain - both may skew miRNA representation. SIX1 and SIX2 mutations affect a single hotspot (Q177R) in the homeodomain indicative of a dominant effect. In larger cohorts, these mutations cluster in blastemal and chemotherapy-induced regressive tumors that likely derive from blastemal cells and these are characterized by generally higher SIX1/2 expression. These findings broaden the spectrum of human cancer genes and may open new avenues for stratification and therapeutic leads for Wilms tumors. 53 Wilms tumor samples were selected for RNA extraction and hybridization on Affymetrix Affymetrix Human Genome U133 Plus 2.0 Arrays.
Project description:Wilms tumor (nephroblastoma) is a pediatric kidney tumor that arises from renal progenitor cells. Since the blastemal type is associated with adverse prognosis, we characterized such Wilms tumors by exome and transcriptome analysis. We detected novel, recurrent somatic mutations affecting the SIX1/2 – SALL1 pathway implicated in kidney development, the DROSHA/DGCR8 microprocessor genes as well as alterations in MYCN and TP53, the latter being strongly associated with dismal outcome. The DROSHA mutations impair the RNase III domains, while DGCR8 exhibits stereotypic E518K mutations in the RNA binding domain - both may skew miRNA representation. SIX1 and SIX2 mutations affect a single hotspot (Q177R) in the homeodomain indicative of a dominant effect. In larger cohorts, these mutations cluster in blastemal and chemotherapy-induced regressive tumors that likely derive from blastemal cells and these are characterized by generally higher SIX1/2 expression. These findings broaden the spectrum of human cancer genes and may open new avenues for stratification and therapeutic leads for Wilms tumors.
Project description:Blastemal histology in chemotherapy-treated pediatric Wilms tumors (nephroblastoma) is associated with adverse prognosis. To uncover the underlying tumor biology and find novel therapeutic leads for this subgroup of patients, we analyzed 58 blastemal-type Wilms tumors by exome and transcriptome sequencing and validated our findings in a large independent replication cohort. Recurrent mutations identified either somatically or in the germline included a hotspot mutation (Q177R) in the homeodomain of SIX1 and SIX2 in tumors with high proliferative potential, mutations in microprocessor genes like DROSHA, DGCR8, DICER1 and DIS3L2, and alterations in IGF2, MYCN, and TP53, the latter being strongly associated with dismal outcome. DROSHA and DGCR8 mutations had a strong effect on miRNA expression patterns in tumors, which was functionally validated in cell lines transfected with mutant DROSHA. total samples analyzed are 16, each done as technical replicate
Project description:Blastemal histology in chemotherapy-treated pediatric Wilms tumors (nephroblastoma) is associated with adverse prognosis. To uncover the underlying tumor biology and find novel therapeutic leads for this subgroup of patients, we analyzed 58 blastemal-type Wilms tumors by exome and transcriptome sequencing and validated our findings in a large independent replication cohort. Recurrent mutations identified either somatically or in the germline included a hotspot mutation (Q177R) in the homeodomain of SIX1 and SIX2 in tumors with high proliferative potential, mutations in microprocessor genes like DROSHA, DGCR8, DICER1 and DIS3L2, and alterations in IGF2, MYCN, and TP53, the latter being strongly associated with dismal outcome. DROSHA and DGCR8 mutations had a strong effect on miRNA expression patterns in tumors, which was functionally validated in cell lines transfected with mutant DROSHA.
Project description:Blastemal histology in chemotherapy-treated pediatric Wilms tumors (nephroblastoma) is associated with adverse prognosis. In order to find novel therapeutic leads for this subgroup of patients, we analyzed 58 such Wilms tumors by exome and transcriptome analysis and validated our findings in larger independent cohorts. Recurrent mutations identified either somatically or in the germline included a hotspot mutation (Q177R) in the homeodomain of SIX1 and SIX2 in tumors with high proliferative potential, mutations in microprocessor genes like DROSHA, DGCR8, DICER1 and DIS3L2, and alterations in IGF2, MYCN, and TP53, the latter being strongly associated with dismal outcome. DROSHA and DGCR8 mutations had a strong effect on miRNA profiles in tumors, which we confirmed in cell lines transfected with mutant DROSHA.
Project description:The Microprocessor complex, consisting of DROSHA and DGCR8, is essential for miRNA maturation and gene regulation. Mutations in these proteins are associated with Wilms tumor (WiT), a common pediatric kidney cancer. To explore the impact of these mutations on WiT pathogenesis, we developed the Microsensor system, a novel tool for dynamically monitoring Microprocessor activity in human cells. Using this system, we engineered HEK293T cells to express the DGCR8-E518K mutation, which was previously identified in WiT patients. Our results show that this mutation significantly impairs the Microprocessor's ability to process specific pri-miRNAs in vitro and alters the miRNA expression profiles. This study demonstrates the utility of the Microsensor system in investigating the molecular mechanisms underlying mutations related to the Microprocessor complex.
Project description:The Microprocessor complex, consisting of DROSHA and DGCR8, is essential for miRNA maturation and gene regulation. Mutations in these proteins are associated with Wilms tumor (WiT), a common pediatric kidney cancer. To explore the impact of these mutations on WiT pathogenesis, we developed the Microsensor system, a novel tool for dynamically monitoring Microprocessor activity in human cells. Using this system, we engineered HEK293T cells to express the DGCR8-E518K mutation, which was previously identified in WiT patients. Our results show that this mutation significantly impairs the Microprocessor's ability to process specific pri-miRNAs in vitro and alters the miRNA expression profiles. This study demonstrates the utility of the Microsensor system in investigating the molecular mechanisms underlying mutations related to the Microprocessor complex.
Project description:In mammalian cells, primary miRNAs are cleaved at their hairpin structures by the Microprocessor complex, whose core is composed of DROSHA and DGCR8. Here, we show that 5’flanking regions, resulting from Microprocessor cleavage, are targeted by the RNA exosome in mouse embryonic stem cells (mESCs). This is facilitated by a physical link between DGCR8 and the nuclear exosome targeting (NEXT) component ZCCHC8. Surprisingly, however, both biochemical and mutagenesis studies demonstrate that a variant NEXT complex, containing the RNA helicase MTR4 but devoid of the RNA-binding protein RBM7, is the active entity. This Microprocessor-NEXT variant also targets stem-loop containing RNAs expressed from other genomic regions, such as enhancers. In contrast, Microprocessor does not contribute to the turnover of less structured NEXT substrates. Our results therefore demonstrate that MTR4-ZCCHC8 can link to either RBM7 or DGCR8/DROSHA to target different RNA substrates depending on their structural context.
Project description:Through whole-exome sequencing we identified somatic missense mutations in DICER1 and DROSHA in Wilms tumor, a childhood kidney cancer. DICER1 and DROSHA are key enzymes in the microRNA biogenesis pathway. To determine the effect of these mutations on microRNA expression, we prepared small RNAs from Wilms tumors and used next-generation sequencing to determine the expression levels of microRNAs in the tumors. Comparison of miRNA expression in tumors with and without mutations in DICER1 or DROSHA.
Project description:We addressed the requirement of DGCR8, DROSHA and DICER functions in developing and adult Schwann cells (SCs) using mouse mutants. We found that the microprocessor components DGCR8 and DROSHA are crucial for axonal radial sorting and to establish correct SC numbers upon myelination. Transcriptome analysis revealed that the microprocessor is essential to prevent aberrant accumulation and de novo expression of injury-response genes. Those genes are predicted targets of stage-specifically enriched miRNAs. In agreement, DGCR8 and DICER are required for proper maintenance of the myelinated SC state. We conclude that the miRNA pathway is crucial for preventing inappropriate activity of injury response genes in developing and adult SCs.