A search for doxycycline-dependent mutations that increase Drosophila melanogaster life span identifies the VhaSFD, Sugar baby, filamin, fwd and Cctl genes

BACKGROUND: A P-type transposable element called PdL has been engineered with a doxycycline-inducible promoter directed out through the 3' end of the element. Insertion of PdL near the 5' end of a gene often yields doxycycline-dependent overexpression of that gene and a mutant phenotype. This functional genomics strategy allows for efficient screening of large numbers of genes for overexpression phenotypes. RESULTS: PdL was mobilized to around 10,000 new locations in the Drosophila melanogaster genome and used to search for genes that would extend life span when overexpressed. Six lines were identified in which there was a 5-17% increase in life span in the presence of doxyxcycline. The mutations were molecularly characterized and in each case a gene was found to be overexpressed using northern blots. Two genes did not have previously known phenotypes and are implicated in membrane transport: VhaSFD encodes a regulatory subunit of the vacuolar ATPase proton pump (H(+)-ATPase), whereas Sugar baby (Sug) is related to a maltose permease from Bacillus. Three PdL mutations identified previously characterized genes: filamin encodes the homolog of an actin-polymerizing protein that interacts with presenilins. four wheel drive (fwd) encodes a phosphatidylinositol-4-kinase (PI 4-kinase) and CTP:phosphocholine cytidylyltransferase-l (Cctl) encodes the rate-limiting enzyme in phosphatidylcholine synthesis. Finally, an apparently novel gene (Red herring, Rdh) was found in the first intron of the encore gene. CONCLUSIONS: Screening for conditional mutations that increase Drosophila life span has identified genes implicated in membrane transport, phospholipid metabolism and signaling, and actin cytoskeleton organization

Transcriptional profiling of MnSOD-mediated lifespan extension in Drosophila reveals a species-general network of aging and metabolic genes.

BACKGROUND: Several interventions increase lifespan in model organisms, including reduced insulin/insulin-like growth factor-like signaling (IIS), FOXO transcription factor activation, dietary restriction, and superoxide dismutase (SOD) over-expression. One question is whether these manipulations function through different mechanisms, or whether they intersect on common processes affecting aging. RESULTS: A doxycycline-regulated system was used to over-express manganese-SOD (MnSOD) in adult Drosophila, yielding increases in mean and maximal lifespan of 20%. Increased lifespan resulted from lowered initial mortality rate and required MnSOD over-expression in the adult. Transcriptional profiling indicated that the expression of specific genes was altered by MnSOD in a manner opposite to their pattern during normal aging, revealing a set of candidate biomarkers of aging enriched for carbohydrate metabolism and electron transport genes and suggesting a true delay in physiological aging, rather than a novel phenotype. Strikingly, cross-dataset comparisons indicated that the pattern of gene expression caused by MnSOD was similar to that observed in long-lived Caenorhabditis elegans insulin-like signaling mutants and to the xenobiotic stress response, thus exposing potential conserved longevity promoting genes and implicating detoxification in Drosophila longevity. CONCLUSION: The data suggest that MnSOD up-regulation and a retrograde signal of reactive oxygen species from the mitochondria normally function as an intermediate step in the extension of lifespan caused by reduced insulin-like signaling in various species. The results implicate a species-conserved net of coordinated genes that affect the rate of senescence by modulating energetic efficiency, purine biosynthesis, apoptotic pathways, endocrine signals, and the detoxification and excretion of metabolites.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are

Mifepristone Increases Life Span in Female Drosophila Without Detectable Antibacterial Activity

Mifepristone dramatically increases the life span of mated female Drosophila while reducing the expression of innate immune response genes. Previous results indicated that mifepristone also reduced the load of aero-tolerant bacteria in mated females. Experiments were conducted to further investigate the possible role of bacteria in mifepristone life span effects. Life span was assayed in flies grown from sterilized eggs on autoclaved media and in normally cultured controls in two independent assays. Sterilization increased mated female life span (+8.3% and +57%, respectively), and the effect of mifepristone was additive (+53% and +93%, respectively). High-throughput sequencing of 16S sequences revealed that sterilization reduced the abundance of multiple species and the classes Bacteroidia, Bacilli, Actinobacteria, and Cytophagia. By contrast, mifepristone caused no decreases and instead increased the abundance of three species. Five aero-tolerant bacterial species were cultured from extracts of mated female flies, including both Gram-positive and Gram-negative species (Acetobacter sicerae, Enterococcus faecalis, Lactobacillus plantarum, Serratia rubidea, and Paenibacillus glucanolyticus). There was no detectable effect of mifepristone on the growth of these bacteria in vitro, indicating that mifepristone does not have a direct antibiotic effect. To test if antibiotics could mimic the effects of mifepristone in vivo, mated female flies were treated throughout adult life span with high concentrations of the individual antibiotics doxycycline, ampicillin, kanamycin, and streptomycin, in replicate experiments. No significant effect on life span was observed for ampicillin, kanamycin, or streptomycin, and an inconsistent benefit was observed for doxycycline. Finally, supplementation of media with Enterococcus faecalis did not alter adult female life span in the presence or absence of mifepristone. Taken together, the results indicate the life span benefits of mifepristone are not due to an antibiotic effect

Translational models for vascular cognitive impairment: a review including larger species.

BACKGROUND: Disease models are useful for prospective studies of pathology, identification of molecular and cellular mechanisms, pre-clinical testing of interventions, and validation of clinical biomarkers. Here, we review animal models relevant to vascular cognitive impairment (VCI). A synopsis of each model was initially presented by expert practitioners. Synopses were refined by the authors, and subsequently by the scientific committee of a recent conference (International Conference on Vascular Dementia 2015). Only peer-reviewed sources were cited. METHODS: We included models that mimic VCI-related brain lesions (white matter hypoperfusion injury, focal ischaemia, cerebral amyloid angiopathy) or reproduce VCI risk factors (old age, hypertension, hyperhomocysteinemia, high-salt/high-fat diet) or reproduce genetic causes of VCI (CADASIL-causing Notch3 mutations). CONCLUSIONS: We concluded that (1) translational models may reflect a VCI-relevant pathological process, while not fully replicating a human disease spectrum; (2) rodent models of VCI are limited by paucity of white matter; and (3) further translational models, and improved cognitive testing instruments, are required