RNAs associated with LARK in Drosophila pharate adult brain
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ABSTRACT:
ORGANISM(S): Drosophila melanogaster
PROVIDER: GSE6418 | GEO | 2006/12/06
SECONDARY ACCESSION(S): PRJNA99485
REPOSITORIES: GEO
Similar Datasets
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.
2008-06-14 | E-GEOD-6418 | biostudies-arrayexpress
Project description:The mammalian circadian timing system consists of a master pacemaker in the suprachiasmatic nucleus (SCN) that synchronizes self-sustained oscillators in most peripheral cells. Rhythmic gene expression in peripheral tissues can be driven by cyclic systemic cues emanating from the SCN or by local oscillators. To discriminate between these two mechanisms, we engineered a mouse strain with a conditionally active liver clock. Transcriptome profiling revealed that the circadian transcription of most genes depends on functional hepatocyte clocks. However, the expression of 31 genes, including mPer2, oscillates robustly in clock-arrested hepatocytes. Such genes may be implicated in the synchronization of liver oscillators
2006-12-30 | E-MEXP-842 | biostudies-arrayexpress
Project description:Intercellular coupling is crucial to prevent desynchronization of cell-autonomous oscillator networks and thus, the disruption of circadian tissue functions. While, neuronal oscillators within the mammalian central clock, the suprachiasmatic nucleus (SCN), couple intercellularly via the exchange of secreted neurotransmitters, intercellular coupling among peripheral oscillators is highly debated and molecular mechanisms are unknown. In our study, we show that peripheral circadian oscillators couple intercellularly via the exchange of secreted signaling molecules and identify TGF-beta as peripheral coupling factor. TGF-beta signaling induces the cAMP response element dependent, immediate-early expression of the clock gene PER2, thereby phase-adjusting the molecular circadian oscillator. Genetic or pharmacologic disruption of TGF-beta signaling causes desynchronization of cellular oscillators resulting in amplitude reduction and increased sensitivity towards Zeitgeber cues. Our findings reveal a previously unknown mechanism of peripheral coupling and open a new perspective on the importance of peripheral clock synchrony for rhythmic organ functions and circadian health.
2021-07-23 | GSE158577 | GEO
Project description:To screen for specific circadian outputs that may distinguish the pacemaker in the mammalian suprachiasmatic nucleus (SCN) from peripheral-type oscillators in which the canonical clockworks are similarly regulated in a circadian manner, the rhythmic behavior of the transcriptome in forskolin-stimulated NIH/3T3 fibroblasts was analyzed and compared to that found in the rat SCN in vivo and SCN2.2 cells in vitro. Similar to the scope of circadian gene expression in SCN2.2 cells and the rat SCN, NIH/3T3 fibroblasts exhibited circadian fluctuations in the expression of the core clock genes, Per2, Bmal1 (Mop3), and Cry1 and 323 functionally diverse transcripts (2.6%), many of which were involved in cell communication. Overlap in rhythmically-expressed transcripts among NIH/3T3 fibroblasts, SCN2.2 cells and the rat SCN was limited to these clock genes and four other genes that mediate fatty acid and lipid metabolism or function as nuclear factors. Compared to NIH/3T3 cells, circadian gene expression in SCN oscillators was more prevalent among cellular pathways mediating glucose metabolism and neurotransmission. Coupled with evidence for the rhythmic regulation of the inducible isoform of nitric oxide synthase, the enzyme responsible for the production of nitric oxide, in SCN2.2 cells and the rat SCN but not in fibroblasts, studies examining the effects of a NOS inhibitor on metabolic rhythms in co-cultures containing SCN2.2 cells and untreated NIH/3T3 cells suggest that this gaseous neurotransmitter may play a key role in SCN pacemaker function. Thus, this comparative analysis of circadian gene expression in SCN and non-SCN cells may have important implications in the selective identification of circadian signals involved in the coupling of SCN oscillators and the regulation of rhythmicity in downstream cells or tissues. Experiment Overall Design: Circadian profiling of the NIH/3T3 fibroblast transcriptome entailed the treatment of NIH/3T3 cells with a 15uM forskolin pulse, subsequent washout of the drug, and collection of total RNA immediately after washout and every 6 hours across two circadian cycles for each of three experiments. Timepoint values reflect the average of three samples from these biological replicates.
2008-06-14 | E-GEOD-5810 | biostudies-arrayexpress
Project description:In mammalian tissues circadian gene expression can be driven by local oscillators or systemic signals controlled by the master pacemaker in the suprachiasmatic nucleus. Here we show that simulated body temperature cycles, but not peripheral oscillators, can control the rhythmic expression of Cold-Inducible RNA binding Protein (CIRP) in cultured fibroblasts. In turn, loss-of-function experiments indicate that CIRP is required for high amplitude circadian gene expression. The transcriptome-wide identification of CIRP-bound RNAs by a biotin-streptavidin based CLIP-seq procedure revealed several CIRP-bound transcripts encoding circadian oscillator proteins. One of these, CLOCK, accumulated to particularly low levels in CIRP-depleted fibroblasts. Since ectopic expression of CLOCK improved circadian gene expression in these cells, we surmise that CIRP confers robustness to circadian oscillators via the regulation of CLOCK expression. Identification of CIRP-interacting RNA molecules in NIH3T3 cells and RNA expression in NIH3T3 cells treated with Control or CIRP siRNA after incubation of the cells at 33M-BM-0C for 8 hours
2012-08-24 | E-GEOD-37685 | biostudies-arrayexpress
Project description:In mammalian tissues circadian gene expression can be driven by local oscillators or systemic signals controlled by the master pacemaker in the suprachiasmatic nucleus. Here we show that simulated body temperature cycles, but not peripheral oscillators, can control the rhythmic expression of Cold-Inducible RNA binding Protein (CIRP) in cultured fibroblasts. In turn, loss-of-function experiments indicate that CIRP is required for high amplitude circadian gene expression. The transcriptome-wide identification of CIRP-bound RNAs by a biotin-streptavidin based CLIP-seq procedure revealed several CIRP-bound transcripts encoding circadian oscillator proteins. One of these, CLOCK, accumulated to particularly low levels in CIRP-depleted fibroblasts. Since ectopic expression of CLOCK improved circadian gene expression in these cells, we surmise that CIRP confers robustness to circadian oscillators via the regulation of CLOCK expression.
2012-08-24 | GSE37685 | GEO
Project description:Little is known about the contribution of translational control to circadian rhythms. To address this issue and in particular translational control by microRNAs (miRNAs), we knocked down the miRNA biogenesis pathway in Drosophila circadian tissues. In combination with an increase in circadian-mediated transcription, this severely affected Drosophila behavioral rhythms, indicating that miRNAs function in circadian timekeeping. To identify miRNA–mRNA pairs important for this regulation, immunoprecipitation of AGO1 followed by microarray analysis identified mRNAs under miRNA-mediated control. They included three core clock mRNAs—clock (clk), vrille (vri), and clockworkorange (cwo). To identify miRNAs involved in circadian timekeeping, we exploited circadian cell-specific inhibition of the miRNA biogenesis pathway followed by tiling array analysis. This approach identified miRNAs expressed in fly head circadian tissue. Behavioral and molecular experiments show that one of these miRNAs, the developmental regulator bantam, has a role in the core circadian pacemaker. S2 cell biochemical experiments indicate that bantam regulates the translation of clk through an association with three target sites located within the clk 39 untranslated region (UTR). Moreover, clk transgenes harboring mutated bantam sites in their 39 UTRs rescue rhythms of clk mutant flies much less well than wild-type CLK transgenes.
2009-08-31 | GSE17627 | GEO
Project description:To screen for specific circadian outputs that may distinguish the pacemaker in the mammalian suprachiasmatic nucleus (SCN) from peripheral-type oscillators in which the canonical clockworks are similarly regulated in a circadian manner, the rhythmic behavior of the transcriptome in forskolin-stimulated NIH/3T3 fibroblasts was analyzed and compared to that found in the rat SCN in vivo and SCN2.2 cells in vitro. Similar to the scope of circadian gene expression in SCN2.2 cells and the rat SCN, NIH/3T3 fibroblasts exhibited circadian fluctuations in the expression of the core clock genes, Per2, Bmal1 (Mop3), and Cry1 and 323 functionally diverse transcripts (2.6%), many of which were involved in cell communication. Overlap in rhythmically-expressed transcripts among NIH/3T3 fibroblasts, SCN2.2 cells and the rat SCN was limited to these clock genes and four other genes that mediate fatty acid and lipid metabolism or function as nuclear factors. Compared to NIH/3T3 cells, circadian gene expression in SCN oscillators was more prevalent among cellular pathways mediating glucose metabolism and neurotransmission. Coupled with evidence for the rhythmic regulation of the inducible isoform of nitric oxide synthase, the enzyme responsible for the production of nitric oxide, in SCN2.2 cells and the rat SCN but not in fibroblasts, studies examining the effects of a NOS inhibitor on metabolic rhythms in co-cultures containing SCN2.2 cells and untreated NIH/3T3 cells suggest that this gaseous neurotransmitter may play a key role in SCN pacemaker function. Thus, this comparative analysis of circadian gene expression in SCN and non-SCN cells may have important implications in the selective identification of circadian signals involved in the coupling of SCN oscillators and the regulation of rhythmicity in downstream cells or tissues. Keywords: Circadian time course
2006-10-31 | GSE5810 | GEO
Project description:The circadian clock represents an evolutionarily acquired gene network that synchronizes physiology to anticipate environmental changes caused by the succession of day and night. While most mammalian cells have a circadian clock, their synchronization depends on a central pacemaker located in the suprachiasmatic nuclei (SCN) of the hypothalamus that integrates light signals. While peripheral organs can be also synchronized by feeding cues and can be uncoupled from the central pacemaker, no impact of peripheral organs on the central clock has been yet observed. Here, we used a mouse chimeric model in which mouse hepatocytes have been replaced by human hepatocytes that have different circadian and signaling properties to characterize such potential feedback. Remarkably, we observed that liver humanization rewired the liver diurnal gene expression and advance the circadian clock by approximately 4 hours. Strikingly, this phase advance was also observed in the muscle and for the entire rhythmic physiology of the animals, with an impact of human hepatocytes on the circadian function of the central clock. Like mice with a deficient central clock, the humanized animals shifted their physiology more rapidly to the light phase under day feeding. This data prompt to reconsider the role of peripheral clocks on the central pacemaker and offers new perspective to understand the impact of diseased organs on the global circadian physiology.
2023-05-25 | GSE212079 | GEO
Project description:Little is known about the contribution of translational control to circadian rhythms. To address this issue and in particular translational control by microRNAs (miRNAs), we knocked down the miRNA biogenesis pathway in Drosophila circadian tissues. In combination with an increase in circadian-mediated transcription, this severely affected Drosophila behavioral rhythms, indicating that miRNAs function in circadian timekeeping. To identify miRNA–mRNA pairs important for this regulation, immunoprecipitation of AGO1 followed by microarray analysis identified mRNAs under miRNA-mediated control. They included three core clock mRNAs—clock (clk), vrille (vri), and clockworkorange (cwo). To identify miRNAs involved in circadian timekeeping, we exploited circadian cell-specific inhibition of the miRNA biogenesis pathway followed by tiling array analysis. This approach identified miRNAs expressed in fly head circadian tissue. Behavioral and molecular experiments show that one of these miRNAs, the developmental regulator bantam, has a role in the core circadian pacemaker. S2 cell biochemical experiments indicate that bantam regulates the translation of clk through an association with three target sites located within the clk 39 untranslated region (UTR). Moreover, clk transgenes harboring mutated bantam sites in their 39 UTRs rescue rhythms of clk mutant flies much less well than wild-type CLK transgenes. Ago IP immunoprecipitation was performed from fly heads collected at different circadian timpoints. For wild type samples 2 biological replicates were collected for each of the six analyzed timepoints from the head protein extract (INPUT) and AGO 1-immunoprecipitated samples (IP). Gene expression was analyzed from both samples by the use of oligonucleotide microarrays. The INPUT sample corresponding to ZT3 has only one replica.
2009-08-31 | E-GEOD-17627 | biostudies-arrayexpress