Project description:Circadian behaviors are regulated by intrinsic biological clocks consisting of central molecular oscillators and output pathways. Despite significant progress in elucidating the central timekeeping mechanisms, the molecular pathways coupling the circadian pacemaker to overt rhythmic behavior and physiology remain elusive. The Drosophila LARK RNA-binding protein is a candidate for such a coupling factor. Previous research indicates that LARK functions downstream of the clock to mediate behavioral outputs. To better understand the roles of LARK in the Drosophila circadian system, we sought to identify RNA molecules associated with LARK in vivo, using a novel strategy that involves capturing the RNA ligands by immunoprecipitation, visualizing the captured RNAs using whole gene microarrays, and identifying functionally relevant targets through genetic screens. Keywords: Association with RNA-binding protein
Project description:Circadian behaviors are regulated by intrinsic biological clocks consisting of central molecular oscillators and output pathways. Despite significant progress in elucidating the central timekeeping mechanisms, the molecular pathways coupling the circadian pacemaker to overt rhythmic behavior and physiology remain elusive. The Drosophila LARK RNA-binding protein is a candidate for such a coupling factor. Previous research indicates that LARK functions downstream of the clock to mediate behavioral outputs. To better understand the roles of LARK in the Drosophila circadian system, we sought to identify RNA molecules associated with LARK in vivo, using a novel strategy that involves capturing the RNA ligands by immunoprecipitation, visualizing the captured RNAs using whole gene microarrays, and identifying functionally relevant targets through genetic screens. Experiment Overall Design: LARK-containing ribonucleoprotein complexes (LARK-RNPs) were precipitated from lysates of hand-dissected pharate adult brains using an affinity-purified anti-LARK antibody (around 1000 brains were used per immunoprecipitation experiment). A portion of each lysate was saved prior to immunoprecipitations (IPs) in order to measure the relative abundance of transcripts in a total RNA sample. RNAs extracted from the LARK-RNP and total RNA samples were labeled and hybridized to Drosophila whole-genome gene microarrays; signal intensities for individual genes were compared between samples to identify those RNAs that were enriched by immunoprecipitation (relative to their abundances in total RNA). RNAs that were selectively enriched in the LARK-RNP samples were considered to be potential targets of the RNA-binding protein. Experiment Overall Design: Due to the difficulty to dissect large amount of fly brains, only two such immunoprecipitation experiments were performed, each generating an IP RNA sample and a total RNA (control) sample. The amount of RNAs obtained from IP is very small thus only one array is used for each sample - i.e. there are only biological replicates and no technical replicate.
Project description:The goal of this study is to identify, in the head of adult flies, mRNA species whose expresson level are altered by overexpression of the Drosophila RNA-binding protein LARK in CNS neurons. Keywords: genetic modification, gene experssion profile
Project description:The goal of this study is to identify, in the head of adult flies, mRNA species whose expresson level are altered by overexpression of the Drosophila RNA-binding protein LARK in CNS neurons. Experiment Overall Design: RNA samples from adult head of the LARK overexpression flies (elav-gal4; uas-lark/+) and control flies were compared. One total RNA sample was isolated from each genotype, of which three technical replicates (repeating the labeling and hybridization processes) were generated, respectively.
Project description:Piwi-interacting (pi) RNAs are a class of germline-expressed small RNAs that have been linked to epigenetic programming in metazoa. C. elegans piRNAs known as 21U-RNAs are defined by more than 15,000 genome-encoded species. To explore the origin of 21U-RNAs we employed methods to enrich the 5' ends of Pol II transcripts. We show that a species of capped-short (cs) RNA is frequently expressed bidirectionally at Pol II loci in C. elegans. Interestingly, at annotated 21U-RNA loci, csRNAs originate precisely 2 nt upstream of the mature piRNA species suggesting that csRNAs are piRNA precursors. In addition, we show that csRNAs associated with TS sites genome-wide define a previously overlooked class of 21U-RNA loci, and nearly double the number of piRNA species available for genome surveillance. Our methods should be of general utility in TS site identification and 5' anchored RNA-expression profiling. Identification of capped RNA including capped small RNA and long capped RNA in C. elegans. The mouse data are independent data to test the CapSeq sequencing protocol.
Project description:All eukaryotic mRNAs contain a 7-methylguanosine (m7G) cap which serves as a platform that recruits proteins to support essential biological functions such as mRNA processing, nuclear export and cap-dependent translation. Although the caping is one of the first steps of transcription and uncapped mRNA is not functional, the fate and turnover of uncapped transcripts have not been studied extensively. Here, we employed fast nuclear depletion of the capping enzymes in yeast Saccharomyces cerevisiae to uncover the turnover of transcripts that failed to be capped. We found that the degradation of non-capped mRNA is mainly performed by Xrn1, the exonuclease which is predominantly localized in the cytoplasm, and the fate of such transcripts is determined principally by the abundance of their synthesis. Nuclear depletion of the capping enzymes increased the levels of poorly expressed mRNAs and non-coding RNAs and did not affect the distribution of RNA Polymerase II on chromatin. Overall, our data indicate that mRNAs that failed to be capped are not directed to any specific quality-control pathway and are stochastically degraded.
Project description:The hub metabolite, nicotinamide adenine dinucleotide (NAD), can be used as an initiating nucleotide in RNA synthesis to result in NAD-capped RNAs (NAD-RNA). Since NAD has been heightened as one of the most essential modulators in aging and various age-related diseases, its attachment to RNA might indicate a yet-to-be discovered mechanism that impacts adult life-course. However, the unknown identity of NAD-linked RNAs in adult and aging tissues has hindered functional studies. Here, we introduce ONE-seq method to identify the RNA transcripts that contain NAD cap. ONE-seq has been optimized to use only one-step chemo-enzymatic biotinylation, followed by streptavidin capture and the nudix phosphohydrolase NudC-catalyzed elution, to specifically recover NAD-capped RNAs for epitranscriptome and gene-specific analyses. Our data describes more than a thousand of previously unknown NAD-RNAs in the mouse liver and reveals epitranscriptome-wide dynamics of NAD-RNAs with age.ONE-seq empowers the identification of NAD-capped RNAs that are responsive to distinct physiological states, facilitating functional investigation into this modification.