In animals, the piRNA pathway preserves the integrity of gametic genomes, guarding them against the activity of mobile genetic elements. This innate immune mechanism relies on distinct genomic loci, termed piRNA clusters, to provide a molecular definition of transposons, enabling their discrimination from genes. piRNA clusters give rise to long, single-stranded precursors which are processed into primary piRNAs through an unknown mechanism. These can engage in an adaptive amplification loop, the ping-pong cycle, to optimize the content of small RNA populations via the generation of secondary piRNAs. Many proteins have been ascribed functions in either primary biogenesis or the ping-pong cycle, though for the most part the molecular functions of proteins implicated in these pathways remain obscure. Here, we link shutdown, a gene previously shown to be required for fertility in Drosophila, to the piRNA pathway. Analysis of knockdown phenotypes in both the germline and somatic compartments of the ovary demonstrate important roles for shutdown in both primary biogenesis and the ping-pong cycle. shutdown is a member of the FKBP family of immunophilins. Shu contains domains implicated in peptidyl-prolyl cis-trans isomerase activity and in the binding of HSP90-family chaperones, though the relevance of these domains to piRNA biogenesis is unknown. Overall design: Analysis of mRNA expression in Drosophila OSS cells transfected with GFP dsRNA. One sample and replicate, used to establish the OSS baseline transcriptome in the presence of exogenous RNAi activity.
shutdown is a component of the Drosophila piRNA biogenesis machinery.
Specimen part, Subject
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Drosophila H1 regulates the genetic activity of heterochromatin by recruitment of Su(var)3-9.
Specimen part
View SamplesIndicated cells were subjected to RNAi against linker histone H1, Nautilus (control), or GFP (control). RNA was isolated and subjected to Affymetrix GeneChIP Drosophila Genome 2.0 arrays
Drosophila H1 regulates the genetic activity of heterochromatin by recruitment of Su(var)3-9.
Specimen part
View SamplesCombining RNAi in cultured cells and analysis of mutant animals, we probed roles of known piRNA pathway components in the initiation and effector phases of transposon silencing. Overall design: total RNA and RNA associated with Piwi was isolated and size-fractionated by PAGE into 19-29nt. These were processed and sequenced on Illumina Genome Analyzer II.
Probing the initiation and effector phases of the somatic piRNA pathway in Drosophila.
Specimen part, Subject
View SamplesSalivary glands or larval ovaries were isolated from transgenic flies expressing RNAi targeting Nautilus (control) or linker histone H1 using a Tub-Gal4 driver. Overall design: ~200 larvae were used to isolate salivary glands or ovaries, independently. Total RNA was isolated using Trizol reagent following manufacturer''s guidelines. Then 5 µg of total RNA was separated on a polyacrylamide gel, and 18-29 nt small RNAs were isolated for cloning.
Drosophila H1 regulates the genetic activity of heterochromatin by recruitment of Su(var)3-9.
Specimen part, Subject
View SamplesThe X-linked DDX3X gene encodes an ATP-dependent DEAD-box RNA helicase frequently altered in various human cancers including melanomas. Despite its important roles in translation and splicing, how DDX3X dysfunction specifically rewires gene expression in melanoma remains completely unknown. Here we uncover a DDX3X-driven post-transcriptional program that dictates melanoma phenotype and poor disease prognosis. Through an unbiased analysis of translating ribosomes we identified the microphtalmia-associated transcription factor, MITF, as a key DDX3X translational target that directs a proliferative-to-metastatic phenotypic switch in melanoma cells. Mechanistically, DDX3X controls MITF mRNA translation via an internal ribosome entry site (IRES) embedded within the 5' untranslated region. Through this exquisite translation-based regulatory mechanism, DDX3X steers MITF protein levels dictating melanoma metastatic potential in vivo and response to targeted therapy. Together these findings unravel a post-transcriptional layer of gene regulation that may provide a unique therapeutic vulnerability in aggressive male melanomas. Overall design: We sequenced transcripts associated with translationally active ribosomes (polysomes) isolated by sucrose gradient fractionation from DDX3X and control siRNA-transduced HT144 cells. Experiments were performed in duplicates.
The X-Linked DDX3X RNA Helicase Dictates Translation Reprogramming and Metastasis in Melanoma.
Specimen part, Cell line, Subject
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Aerobic glycolysis tunes YAP/TAZ transcriptional activity.
Cell line, Treatment
View SamplesReprogramming of cancer cell metabolism toward aerobic glycolysis, i.e. the Warburg effect, is a hallmark of cancer; according to current views, the rationale for selecting such energy-inefficient metabolism is the need to increase cellular biomass to sustain production of daughter cells and proliferation. In this view, metabolic reprogramming is considered as a simple phenotypic endpoint that occurs as a consequence of signal transduction mechanisms, including oncogene-driven nutrient uptake and metabolic rewiring. A newly emerging paradigm is instead that transcriptional networks and oncogenic signaling can also be regulated downstream of metabolic pathways, that assume causative roles in controlling cancer cell behavior, above and beyond their core biochemical function. To explore possible links between glucose metabolism and nuclear gene transcription we compared immortalized mammary epithelial cells (MCF10A) and metastatic breast cancer cells (MDA-MB-231) growing in high glucose or in the presence of a widely used inhibitor of glucose uptake / glucose metabolism, 2-deoxy-glucose (2DG).
Aerobic glycolysis tunes YAP/TAZ transcriptional activity.
Cell line, Treatment
View SamplesYAP1 (Yes-associated protein 1) and TAZ (transcriptional coactivator with PDZ-binding motif, or WWTR1) are nucleo-cytoplasmic shuttling proteins that can function in the nucleus as transcriptional coactivators. Their role in regulating gene transcription has been so far mainly investigated by overexpressing YAP1 or TAZ, while here we sought to determine which genes are regulated by endogenous levels of YAP/TAZ. To this end, we compared MCF10A cells transfected with a control non-targeting siRNA to cells transfected with two independent mixes of siRNA targeting both YAP and TAZ.
Aerobic glycolysis tunes YAP/TAZ transcriptional activity.
Cell line
View SamplesYAP1 (Yes-associated protein 1) and TAZ (transcriptional coactivator with PDZ-binding motif, or WWTR1) are nucleo-cytoplasmic shuttling proteins that can function in the nucleus as transcriptional coactivators. Their role in regulating gene transcription has been so far mainly investigated by overexpressing YAP1 or TAZ, while here we sought to determine which genes are regulated by endogenous levels of YAP/TAZ. To this end, we compared MCF10A cells transfected with a control non-targeting siRNA to cells transfected with two independent mixes of siRNA targeting both YAP and TAZ.
Aerobic glycolysis tunes YAP/TAZ transcriptional activity.
Cell line
View Samples