ABSTRACT: Sirt6 is a multifunctional enzyme that regulates diverse cellular processes such as metabolism, DNA repair, and aging. Overexpressing Sirt6 extends lifespan in mice, but the underlying cellular mechanisms are unclear. Drosophila melanogaster are an excellent model to study genetic regulation of lifespan; however, despite extensive study in mammals, very little is known about Sirt6 function in flies. Here, we characterized the Drosophila ortholog of Sirt6, dSirt6, and examined its role in regulating longevity. dSirt6 is a nuclear and chromatin-associated protein with NAD+-dependent histone deacetylase activity. dSirt6 overexpression in flies produces robust lifespan extension in both sexes, while reducing dSirt6 levels shortens lifespan. dSirt6 OE flies have normal food consumption and fertility, but increased resistance to oxidative stress and reduced protein synthesis rates. Transcriptomic analyses reveal that dSirt6 OE reduces expression of genes involved in ribosome biogenesis, including many dMyc target genes. dSirt6 OE partially rescues many effects of dMyc OE, including increased nuclear size, up-regulation of ribosome biogenesis genes, and lifespan shortening. Lastly, dMyc haploinsufficiency does not convey additional lifespan extension to dSirt6 OE flies, suggesting dSirt6 OE is upstream of dMyc in regulating lifespan. Our results provide new insight into the mechanisms by which Sirt6 overexpression leads to longer lifespan.
Project description:Eukaryotic elongation factor 2 (eEF2) undergoes a unique post-translational modification called diphthamidation. Although eEF2 diphthamidation is highly conserved, its pathophysiological function is still largely unknown. To elucidate the function of diphthamidation in tumor, we examined the involvement of diphthamidation pathway enzyme Dph5 in tumor progression in Drosophila adult gut. Expression of oncogenic RasV12 in gut intestinal stem cells (ISCs) and enteroblasts (EBs) causes hypertrophy and disruption of gut epithelia, and shortened lifespan. Knockdown of dph5 ameliorated these pathogenic phenotypes. Dph5 is required for gross translation activation and high dMyc protein level in RasV12 tumor-like hyperplasia. Transcriptome analysis revealed that Dph5 is involved in the regulation of ribosome biogenesis genes. These results suggest that diphthamidation is required for translation activation partly through the regulation of ribosome biogenesis in Ras-induced tumor-like hyperplasia model in Drosophila gut.
Project description:Myc oncoproteins are essential regulators of the growth and proliferation of mammalian cells. In Drosophila the single ortholog of Myc (dMyc), encoded by the dm gene, influences organismal size and the growth of both mitotic and endoreplicating cells. A null mutation in dm (dm4) results in attenuated endoreplication and growth arrest early in larval development. Gene expression analysis indicates that loss of dMyc leads to decreased expression of genes required for ribosome biogenesis and protein synthesis. Keywords: cDNA expression microarray, mutant analysis
Project description:dMyc is a conserved transcription factor that controls growth and proliferation by regulating its target genes. We used Affymetrix microarray to identify and classify targets of dMyc during Drosophila embryogenesis. RNA was extracted from 0-24 hour old Drosophila embryos in control (Gal 4 expressing animals) and Myc+ (flies over-expressing dMyc under UAS enhancer) to identify genomic targets od dMyc during embryogenesis
Project description:Genomes pervasively produce long non-coding RNAs (lncRNAs) of largely unknown functions. Some of these lncRNAs have been implicated in roles related to ageing and associated diseases. Here we characterize aal1 (ageing-associated lncRNA 1) which is induced in non-dividing, ageing cells of fission yeast. Deletion of aal1 shortens the chronological lifespan of non-dividing cells, while ectopic overexpression of aal1 from a plasmid prolongs their lifespan, indicating that this lncRNA acts in trans. We find that aal1 genetically interacts with coding genes functioning in processes related to protein translation, and aal1 overexpression leads to repression of ribosomal protein genes and inhibition of cell growth. The aal1 RNA localizes to the cytoplasm and associates with ribosomes. Notably, aal1 deletion or overexpression is sufficient to increase or decrease the cellular ribosome content, respectively. We identify the mRNA rpl1901, encoding a ribosomal protein, as a binding target of aal1. The expression of rpl1901 is moderately repressed by aal1, and such moderate repression is critical and sufficient to extend the chronological lifespan. Remarkably, expression of the yeast aal1 lncRNA in the fly gut triggers a significant extension of the lifespan in flies. Based on these findings, we propose that the aal1 RNA can reduce the ribosome content by decreasing the levels of the Rpl1901 ribosomal protein, thus attenuating protein translation and promoting longevity. Although the aal1 lncRNA itself is not conserved, its effects in the fly raise the possibility that other organisms feature related mechanisms involving conserved ribosome-associated processes to control ageing.
Project description:<p>Chronic sleep loss profoundly impacts metabolic health and shortens lifespan, but studies of the mechanisms involved have focused largely on acute sleep deprivation. To identify metabolic consequences of chronically reduced sleep, we conducted unbiased metabolomics on heads of three adult Drosophila short-sleeping mutants with very different mechanisms of sleep loss: fumin (fmn), redeye (rye), and sleepless (sss). Common features included elevated ornithine and polyamines, with lipid, acyl-carnitine, and TCA cycle changes suggesting mitochondrial dysfunction. Studies of excretion demonstrate inefficient nitrogen elimination in adult sleep mutants, likely contributing to their polyamine accumulation. Increasing levels of polyamines, particularly putrescine, promote sleep in control flies but poison sleep mutants. This parallels the broadly enhanced toxicity of high dietary nitrogen load from protein in chronically sleep-restricted Drosophila, including both sleep mutants and flies with hyper-activated wake-promoting neurons. Together, our results implicate nitrogen stress as a novel mechanism linking chronic sleep loss to adverse health outcomes-and perhaps for linking food and sleep homeostasis at the cellular level in healthy organisms.</p>
Project description:Myc oncoproteins are essential regulators of the growth and proliferation of mammalian cells. In Drosophila the single ortholog of Myc (dMyc), encoded by the dm gene, influences organismal size and the growth of both mitotic and endoreplicating cells. A null mutation in dm (dm4) results in attenuated endoreplication and growth arrest early in larval development. Gene expression analysis indicates that loss of dMyc leads to decreased expression of genes required for ribosome biogenesis and protein synthesis. Drosophila larvae were collected 24 hours after egg deposition. Sample comparisons were performed using 3 biological independent experimental replicates of dm4 that were each compared to a common reference (wild type larvae of the same genetic background as dm4). For each comparison, a dye-swapped technical replicate was also performed and the paired results were averaged and used as a single observation.
Project description:Overexpression of Atg1 using either weaker CGGAL4 or stronger HRGAL4 driver. Both drivers have same expression pattern and are specific for intestine, Malpighian tubules and fat body of the fruit fly Drosophila melanogaster. Weaker Atg1 overexpression results in longer lifespan whereas stronger Atg1 overexpression shortens lifespan compared to controls. Overexpressor lines were combined with tubGAL80ts, which is a temperature sensitive GAL4 repressor. This enabled induction of Atg1 overexpression in day-2 adult fly, thereby bypassing development and any potential developmental effects that Atg1 might have. Fly eggs of appropriate genotype were raised under standard density at 18C and then emerged flies were switched to 27C at day 2 of adulthood for Atg1 overexpression, and were kept at 27C onwards for longevity analyses. Dissected tissue was collected for the transcriptomic analysis at two weeks of age.
Project description:Dietary restriction (DR) is a robust environmental intervention that slows aging in various species. Changes in fat content have been associated with DR, but whether they play a causal role in mediating various responses to DR remains unknown. We demonstrate that upon DR, Drosophila melanogaster shift their metabolism towards increasing both fatty acid synthesis and breakdown. Inhibition of acetyl CoA carboxylase (ACC), a critical enzyme in fatty acid synthesis, or fatty acid oxidation genes specifically in the muscle tissue inhibited the lifespan extension observed upon DR, suggesting a critical role for intra-myocellular fatty acid metabolism. DR enhances spontaneous activity of flies which was found to be dependent on the enhanced fatty acid metabolism. Furthermore, this increase in activity upon DR was found to partially mediate the lifespan extension upon DR. Over-expression of adipokinetic hormone (dAKH) in whole flies, which increases fat metabolism, led to an increase in spontaneous activity and lifespan in a nutrient dependent manner. Together these results suggest that in Drosophila melanogaster enhanced fat metabolism in the muscle is a key metabolic adaptation in response to DR. 24 experimental samples were analyzed using Nimblegen oligo microarrays. Wild type samples (AL without RU486) were used as the Cy3 reference/control for all experimetal comparisons.
Project description:Genomes pervasively produce long non-coding RNAs (lncRNAs) of largely unknown functions. Some of these lncRNAs have been implicated in roles related to ageing and associated diseases. Here we characterize aal1 (ageing-associated lncRNA 1) which is induced in non-dividing, ageing cells of fission yeast. Deletion of aal1 shortens the chronological lifespan of non-dividing cells, while ectopic overexpression of aal1 from a plasmid prolongs their lifespan, indicating that this lncRNA acts in trans. We find that aal1 genetically interacts with coding genes functioning in processes related to protein translation, and aal1 overexpression leads to repression of ribosomal protein genes and inhibition of cell growth. The aal1 RNA localizes to the cytoplasm and associates with ribosomes. Notably, aal1 deletion or overexpression is sufficient to increase or decrease the cellular ribosome content, respectively. We identify the mRNA rpl1901, encoding a ribosomal protein, as a binding target of aal1. The expression of rpl1901 is moderately repressed by aal1, and such moderate repression is critical and sufficient to extend the chronological lifespan. Remarkably, expression of the yeast aal1 lncRNA in the fly gut triggers a significant extension of the lifespan in flies. Based on these findings, we propose that the aal1 RNA can reduce the ribosome content by decreasing the levels of the Rpl1901 ribosomal protein, thus attenuating protein translation and promoting longevity. Although the aal1 lncRNA itself is not conserved, its effects in the fly raise the possibility that other organisms feature related mechanisms involving conserved ribosome-associated processes to control ageing.
Project description:Genomes pervasively produce long non-coding RNAs (lncRNAs) of largely unknown functions. Some of these lncRNAs have been implicated in roles related to ageing and associated diseases. Here we characterize aal1 (ageing-associated lncRNA 1) which is induced in non-dividing, ageing cells of fission yeast. Deletion of aal1 shortens the chronological lifespan of non-dividing cells, while ectopic overexpression of aal1 from a plasmid prolongs their lifespan, indicating that this lncRNA acts in trans. We find that aal1 genetically interacts with coding genes functioning in processes related to protein translation, and aal1 overexpression leads to repression of ribosomal protein genes and inhibition of cell growth. The aal1 RNA localizes to the cytoplasm and associates with ribosomes. Notably, aal1 deletion or overexpression is sufficient to increase or decrease the cellular ribosome content, respectively. We identify the mRNA rpl1901, encoding a ribosomal protein, as a binding target of aal1. The expression of rpl1901 is moderately repressed by aal1, and such moderate repression is critical and sufficient to extend the chronological lifespan. Remarkably, expression of the yeast aal1 lncRNA in the fly gut triggers a significant extension of the lifespan in flies. Based on these findings, we propose that the aal1 RNA can reduce the ribosome content by decreasing the levels of the Rpl1901 ribosomal protein, thus attenuating protein translation and promoting longevity. Although the aal1 lncRNA itself is not conserved, its effects in the fly raise the possibility that other organisms feature related mechanisms involving conserved ribosome-associated processes to control ageing.