Project description:Background: Cancers are commonly characterised by hypoxia and also by global reductions in the levels of mature microRNAs. We have examined the hypothesis that hypoxia might mediate this reduction through repressive effects on microRNA biogenesis proteins. Methods: Breast cancer cell lines were exposed to hypoxia and manipulations of hypoxia inducible factor (HIF) and HIF hydroxylase activity. The effects of hypoxia on the mRNA and protein levels of enzymes involved in microRNA biogenesis (Dicer, Drosha, TARPB2, DCGR8, XPO5) was determined by RT PCR and immunoblotting. The effect of hypoxia on microRNAs was determined with microarray studies, RT PCR and reporter assays. Results: In breast cancer lines there was significant reduction of Dicer mRNA and protein levels in cells exposed to hypoxia. This effect was independent of HIF but dependent on the HIF hydroxylase PHD2 and was partly mediated by feedback effects via microRNAs. Furthermore, several other proteins with critical roles in microRNA biogenesis (Drosha, TARBP2 and DCGR8) also showed significant and co-ordinated repression under hypoxic conditions. Despite these substantial alterations no, or modest, changes were observed in mature microRNA production Conclusion: These observations provide further and important interfaces between oxygen availability and gene expression and a potential mechanistic explanation for the reduced levels of microRNAs observed in some cancers. They provide further support for the existence of feedback mechanisms in the regulation of the microRNA biogenesis pathway and the relative stability of microRNAs.
Project description:The role of SRF in the regulation of microRNA expression and microRNA biogenesis in cardiac hypertrophy has not been well established. In this report, we employed a distinct transgenic mouse model to study the impact of SRF on cardiac microRNA expression and microRNA biogenesis. Cardiac-specific overexpression of SRF (SRF-Tg) led to altered expression of a number of microRNAs.
Project description:We investigated the effect of Dgcr8-homozygous mutation on microRNA expression profile in mouse embryonic stem cells. MicroRNA expression was substantially impaired, indicating a pivotal role of DGCR8 in microRNA biogenesis.
Project description:we used genome-wide transcriptome analysis to profile the mRNA, long noncoding RNA (lncRNA), and microRNA (miRNA) expression of B10 cells, an antigen-specific Cd1dhiCd5+Cd19hiIl10 competent regulatory B cell. Potential key upstream regulators (including transcription factors, cytokines, trans-membrane receptors, and kinases) for Breg biogenesis and function were identified. B10+ B cells (Cd1dhiCd5+Cd19hiIl10+) and B10- cells (Cd1d-Cd5-Cd19hiIl10-) from mouse splenic B cell were sorted for RNA preparation. Two independent repeats were prepared for microarray analysis
Project description:we used genome-wide transcriptome analysis to profile the mRNA, long noncoding RNA (lncRNA), and microRNA (miRNA) expression of B10 cells, an antigen-specific Cd1dhiCd5+Cd19hiIl10 competent regulatory B cell. Potential key upstream regulators (including transcription factors, cytokines, trans-membrane receptors, and kinases) for Breg biogenesis and function were identified. B10+ B cells (Cd1dhiCd5+Cd19hiIl10+) and B10- cells (Cd1d-Cd5-Cd19hiIl10-) from mouse splenic B cell were sorted for RNA preparation. Two independent repeats were prepared for RNA-seq
Project description:Ars2 is a component of the nuclear cap-binding complex that is required for cellular proliferation and contributes to microRNA biogenesis. Arrays were performed to determine the repertoire of genes that change following knock-down of Ars2. Knock-down of DGCR8 was also performed to determine which changes in Ars2 knock-down cells resulted from defects in microRNA expression. 9 samples were analyzed including: three biological replicates of control siRNA-transfected HeLa cells, HeLa cells transfected with three independent siRNAs targeting Ars2, or HeLa cells transfected with three independent siRNAs targeting DGCR8.
