BRCA1 regulates microRNA biogenesis via the DROSHA microprocessor complex
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ABSTRACT:
SUBMITTER: Shinji Kawai
PROVIDER: S-JCBD-201110008 | bioimages |
REPOSITORIES: bioimages
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Project description:Aberrant RNA-editing was observed in several human tumors, but its significance is mostly unknown. Here we show that ADAR1, a ubiquitous RNA-editing enzyme, is commonly lost in metastatic melanoma cells and specimens. Experimental ADAR1 silencing significantly alters melanoma cell morphology, facilitates proliferation and cell-cycle, and increases the tumorigenicity in-vivo. A series of ADAR1 truncation mutants establishes a novel RNA-editing-independent role for ADAR1 in controlling the nuclear and cytoplasmic processing steps of miRNA biogenesis. Altered expression of ADAR1-controled miRNAs accounts for the observed phenotype. We show that the oncogenic miR-17-5p endogenously regulates ADAR1 expression and that its genomic sequence is frequently amplified in melanoma to overexpress the mature miR-17-5p form. ADAR1 and miR-17-5p are ubiquitously expressed, suggesting the generality of this mechanism. Melanoma cell line expressing low ADAR1 levels (ADAR1-Knockdown) using shRNA technique were selected for RNA extraction and hybridization on Affymetrix microarrays. We sought to examine the alterations in the genes and microRNA expression profile in the manipulated cell system, due to ADAR1 possible involvement cancer development. To that end, we selected ADAR1-knockdown (ADAR1-KD) cells that demonstrated an enhanced aggressive phenotype both in vivo and in vitro as compared to the control cells (Control).
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Project description:TORC1 is a structurally and functionally conserved multiprotein complex that regulates many aspects of eukaryote growth including the synthesis and assembly of ribosomes. The protein kinase activity of this complex is responsive to environmental cues and is potently inhibited by the natural product macrolide rapamycin. Insights into how TORC1 regulates growth have been provided with the recent identification of the rapamycin-sensitive phosphoproteome in yeast. Building on these data, we show here that Sch9, an AGC family kinase and direct substrate of TORC1, promotes ribosome biogenesis (ribi) and ribosomal protein (RP) gene expression via direct inhibitory phosphorylation of three transcription repressors, Stb3, Dot6 and Tod6. Dephosphorylation of these factors allows them to recruit the RPD3L histone deactelyase complex to ribi/RP gene promoters. Since rRNA and tRNA transcription are also under its control, Sch9 appears to be well positioned to coordinately regulate transcriptional aspects of ribosome biogenesis. mRNA-Seq of 8 S. cerevisiae strains treated with either DMSO alone or 1NM-PP1, a small molecule inhibitor for analog-sensitive kinases such as sch9-as.
2011-07-01 | E-GEOD-29122 | biostudies-arrayexpress
Project description:TORC1 is a structurally and functionally conserved multiprotein complex that regulates many aspects of eukaryote growth including the synthesis and assembly of ribosomes. The protein kinase activity of this complex is responsive to environmental cues and is potently inhibited by the natural product macrolide rapamycin. Insights into how TORC1 regulates growth have been provided with the recent identification of the rapamycin-sensitive phosphoproteome in yeast. Building on these data, we show here that Sch9, an AGC family kinase and direct substrate of TORC1, promotes ribosome biogenesis (ribi) and ribosomal protein (RP) gene expression via direct inhibitory phosphorylation of three transcription repressors, Stb3, Dot6 and Tod6. Dephosphorylation of these factors allows them to recruit the RPD3L histone deactelyase complex to ribi/RP gene promoters. Since rRNA and tRNA transcription are also under its control, Sch9 appears to be well positioned to coordinately regulate transcriptional aspects of ribosome biogenesis. ChIP-Seq of 8 S. cerevisiae strains treated with 1NM-PP1, a small molecule inhibitor for analog-sensitive kinases such as sch9-as.
2011-07-01 | E-GEOD-29124 | biostudies-arrayexpress
Project description:WBP2 is an emerging oncoprotein with diverse functions in breast tumorigenesis via regulating Wnt, epidermal growth factor receptor, estrogen receptor, and Hippo. Recently, evidence shows that WBP2 is tightly regulated by the components of the miRNA biogenesis machinery such as DGCR8 and Dicer via producing both WBP2's 3'UTR and coding DNA sequence-targeting miRNAs. This led us to hypothesize that WBP2 could provide a feedback loop to the biogenesis of its key upstream regulators by regulating the microprocessor complex activity. Indeed, WBP2 suppressed microprocessor activity by blocking the processing of pri-miRNAs to pre-miRNAs. WBP2 negatively regulated the assembly of the microprocessor complex via physical interactions with its components. Meta-analyses suggest that microprocessor complex components, in particular DGCR8, DDX5, and DEAD-Box Helicase17 (DDX17), have tumor-suppressive properties. 2D and 3D in vitro proliferation assays revealed that WBP2 blocked the tumor-suppressive properties of DGCR8, a key component of the microprocessor complex. In conclusion, WBP2 is a novel regulator of miRNA biogenesis that is a known dysregulated pathway in breast tumorigenesis. The reregulation of miRNA biogenesis machinery via targeting WBP2 protein may have implications in breast cancer therapy.
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Project description:This SuperSeries is composed of the SubSeries listed below.
2011-07-01 | GSE29125 | GEO
Project description:BACKGROUND:Hydrogen sulfide (H2S) is an important regulator of mitochondrial bioenergetics, but its role in regulating mitochondrial biogenesis is not well understood. Using both genetic and pharmacological approaches, we sought to determine if H2S levels directly influenced cardiac mitochondrial content. RESULTS:Mice deficient in the H2S-producing enzyme, cystathionine γ-lyase (CSE KO) displayed diminished cardiac mitochondrial content when compared to wild-type hearts. In contrast, mice overexpressing CSE (CSE Tg) and mice supplemented with the orally active H2S-releasing prodrug, SG-1002, displayed enhanced cardiac mitochondrial content. Additional analysis revealed that cardiac H2S levels influenced the nuclear localization and transcriptional activity of peroxisome proliferator-activated receptor γ coactivator 1α (PGC1α) with higher levels having a positive influence and lower levels having a negative influence. Studies aimed at evaluating the underlying mechanisms found that H2S required AMP-activated protein kinase (AMPK) to induce PGC1α signaling and mitochondrial biogenesis. Finally, we found that restoring H2S levels with SG-1002 in the setting of heart failure increased cardiac mitochondrial content, improved mitochondrial respiration, improved ATP production efficiency, and improved cardiac function. CONCLUSIONS:Together, these results suggest that hydrogen sulfide is an important regulator of cardiac mitochondrial content and establishes that exogenous hydrogen sulfide can induce mitochondrial biogenesis via an AMPK-PGC1α signaling cascade.
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