The roles of juvenile hormone, insulin/target of rapamycin, and ecydsone signaling in regulating body size in Drosophila.
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ABSTRACT:
SUBMITTER: Mirth CK
PROVIDER: S-EPMC4594587 | biostudies-other | 2014 Oct
REPOSITORIES: biostudies-other
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Project description:The role of juvenile hormone (JH) in regulating the timing and nature of insect molts is well-established. Increasing evidence suggests that JH is also involved in regulating final insect size. Here we elucidate the developmental mechanism through which JH regulates body size in developing Drosophila larvae by genetically ablating the JH-producing organ, the corpora allata (CA). We found that larvae that lack CA pupariated at smaller sizes than control larvae due to a reduced larval growth rate. Neither the timing of the metamorphic molt nor the duration of larval growth was affected by the loss of JH. Further, we show that the effects of JH on growth rate are dependent on the forkhead box O transcription factor (FOXO), which is negatively regulated by the insulin-signaling pathway. Larvae that lacked the CA had elevated levels of FOXO activity, whereas a loss-of-function mutation of FOXO rescued the effects of CA ablation on final body size. Finally, the effect of JH on growth appears to be mediated, at least in part, via ecdysone synthesis in the prothoracic gland. These results indicate a role of JH in regulating growth rate via the ecdysone- and insulin-signaling pathways.
| S-EPMC4024895 | biostudies-other
Project description:Genetic analysis in Drosophila melanogaster has been widely used to identify a system of genes that control cell growth in response to insulin and nutrients. Many of these genes encode components of the insulin receptor/target of rapamycin (InR/TOR) pathway. However, the biochemical context of this regulatory system is still poorly characterized in Drosophila. Here, we present the first quantitative study that systematically characterizes the modularity and hormone sensitivity of the interaction proteome underlying growth control by the dInR/TOR pathway. Applying quantitative affinity purification and mass spectrometry, we identified 97 high confidence protein interactions among 58 network components. In all, 22% of the detected interactions were regulated by insulin affecting membrane proximal as well as intracellular signaling complexes. Systematic functional analysis linked a subset of network components to the control of dTORC1 and dTORC2 activity. Furthermore, our data suggest the presence of three distinct dTOR kinase complexes, including the evolutionary conserved dTTT complex (Drosophila TOR, TELO2, TTI1). Subsequent genetic studies in flies suggest a role for dTTT in controlling cell growth via a dTORC1- and dTORC2-dependent mechanism.
| S-EPMC3261712 | biostudies-literature
Project description:In insects, control of body size is intimately linked to nutritional quality as well as environmental and genetic cues that regulate the timing of developmental transitions. Prothoracicotropic hormone (PTTH) has been proposed to play an essential role in regulating the production and/or release of ecdysone, a steroid hormone that stimulates molting and metamorphosis. In this report, we examine the consequences on Drosophila development of ablating the PTTH-producing neurons. Surprisingly, PTTH production is not essential for molting or metamorphosis. Instead, loss of PTTH results in delayed larval development and eclosion of larger flies with more cells. Prolonged feeding, without changing the rate of growth, causes the overgrowth and is a consequence of low ecdysteroid titers. These results indicate that final body size in insects is determined by a balance between growth-rate regulators such as insulin and developmental timing cues such as PTTH that set the duration of the feeding interval.
| S-EPMC2359579 | biostudies-literature
Project description:BackgroundJuvenile hormone (JH) has been demonstrated to control adult lifespan in a number of non-model insects where surgical removal of the corpora allata eliminates the hormone's source. In contrast, little is known about how juvenile hormone affects adult Drosophila melanogaster. Previous work suggests that insulin signaling may modulate Drosophila aging in part through its impact on juvenile hormone titer, but no data yet address whether reduction of juvenile hormone is sufficient to control Drosophila life span. Here we adapt a genetic approach to knock out the corpora allata in adult Drosophila melanogaster and characterize adult life history phenotypes produced by reduction of juvenile hormone. With this system we test potential explanations for how juvenile hormone modulates aging.ResultsA tissue specific driver inducing an inhibitor of a protein phosphatase was used to ablate the corpora allata while permitting normal development of adult flies. Corpora allata knockout adults had greatly reduced fecundity, inhibited oogenesis, impaired adult fat body development and extended lifespan. Treating these adults with the juvenile hormone analog methoprene restored all traits toward wildtype. Knockout females remained relatively long-lived even when crossed into a genotype that blocked all egg production. Dietary restriction further extended the lifespan of knockout females. In an analysis of expression profiles of knockout females in fertile and sterile backgrounds, about 100 genes changed in response to loss of juvenile hormone independent of reproductive state.ConclusionsReduced juvenile hormone alone is sufficient to extend the lifespan of Drosophila melanogaster. Reduced juvenile hormone limits reproduction by inhibiting the production of yolked eggs, and this may arise because juvenile hormone is required for the post-eclosion development of the vitellogenin-producing adult fat body. Our data do not support a mechanism for juvenile hormone control of longevity simply based on reducing the physiological costs of egg production. Nor does the longevity benefit appear to function through mechanisms by which dietary restriction extends longevity. We identify transcripts that change in response to juvenile hormone independent of reproductive state and suggest these represent somatically expressed genes that could modulate how juvenile hormone controls persistence and longevity.
| S-EPMC3726347 | biostudies-literature
Project description:Multi-cellular organisms need to successfully link cell growth and metabolism to environmental cues during development. Insulin receptor-target of rapamycin (InR-TOR) signalling is a highly conserved pathway that mediates this link. Herein, we describe poly, an essential gene in Drosophila that mediates InR-TOR signalling. Loss of poly results in lethality at the third instar larval stage, but only after a stage of extreme larval longevity. Analysis in Drosophila demonstrates that Poly and InR interact and that poly mutants show an overall decrease in InR-TOR signalling, as evidenced by decreased phosphorylation of Akt, S6K and 4E-BP. Metabolism is altered in poly mutants, as revealed by microarray expression analysis and a decreased triglyceride : protein ratio in mutant animals. Intriguingly, the cellular distribution of Poly is dependent on insulin stimulation in both Drosophila and human cells, moving to the nucleus with insulin treatment, consistent with a role in InR-TOR signalling. Together, these data reveal that Poly is a novel, conserved (from flies to humans) mediator of InR signalling that promotes an increase in cell growth and metabolism. Furthermore, homology to small subunits of Elongator demonstrates a novel, unexpected role for this complex in insulin signalling.
| S-EPMC3352090 | biostudies-literature
Project description:Background. Juvenile hormone (JH) has been demonstrated to control adult lifespan in a number of non-model insects where surgical removal of the corpora allata eliminates the hormone’s source. In contrast, little is known about how juvenile hormone affects adult Drosophila melanogaster. Previous work suggests that insulin signaling may modulate Drosophila aging in part through its impact on juvenile hormone titer, but no data yet addresses whether reduction of juvenile hormone is sufficient to control Drosophila life span. Here we adapt a recent genetic approach to knock out the corpora allata in adult Drosophila melanogaster and characterize adult life history phenotypes produced by reduction of juvenile hormone. With this system we test potential explanations for how juvenile hormone modulates aging. Conclusions. Reduced juvenile hormone alone is sufficient to extend lifespan of Drosophila melanogaster. Reduced juvenile hormone limits reproduction by inhibiting the production of yolked eggs, and this may arise because juvenile hormone is required for the post-eclosion development of vitellogenin-producing adult fat body. Our data do not support a mechanism for juvenile hormone control of longevity simply based on reducing the physiological costs of reproductive. Nor does the longevity benefit appear to function through mechanisms by which dietary restriction extends longevity. We identify transcripts that change in response to juvenile hormone independent of reproductive state and suggest these represent somatically expressed genes that could modulate how juvenile hormone controls persistence and longevity.
2013-07-26 | GSE48145 | GEO
Project description:Autophagy is a lysosomal degradation pathway that degrades cytoplasmic proteins and organelles. Absence of autophagy in hepatocytes has been linked to promoting liver injury and tumorigenesis; however, the mechanisms behind why a lack of autophagy induces these complications are not fully understood. The role of mammalian target of rapamycin (mTOR) in impaired autophagy-induced liver pathogenesis and tumorigenesis was investigated by using liver-specific autophagy related 5 knockout (L-ATG5 KO) mice, L-ATG5/mTOR, and L-ATG5/Raptor double knockout (DKO) mice. We found that deletion of mTOR or Raptor in L-ATG5 KO mice at 2 months of age attenuated hepatomegaly, cell death, and inflammation but not fibrosis. Surprisingly, at 6 months of age, L-ATG5/mTOR DKO and L-ATG5/Raptor DKO mice also had increased hepatic inflammation, fibrosis, and liver injury, similar to the L-ATG5 KO mice. Moreover, more than 50% of L-ATG5/mTOR DKO and L-ATG5/Raptor DKO mice already developed spontaneous tumors, but none of the L-ATG5 KO mice had developed any tumors at 6 months of age. At 9 months of age, all L-ATG5/mTOR DKO and L-ATG5/Raptor DKO had developed liver tumors. Mechanistically, L-ATG5/mTOR DKO and L-ATG5/Raptor DKO mice had decreased levels of hepatic ubiquitinated proteins and persistent nuclear erythroid 2 p45-related factor 2 activation but had increased Akt activation compared with L-ATG5 KO mice. Conclusion: Loss of mTOR signaling attenuates the liver pathogenesis in mice with impaired hepatic autophagy but paradoxically promotes tumorigenesis in mice at a relatively young age. Therefore, the balance of mTOR is critical in regulating the liver pathogenesis and tumorigenesis in mice with impaired hepatic autophagy.
| S-EPMC6858484 | biostudies-literature
Project description:The insect juvenile hormone receptor is a basic helix-loop-helix (bHLH), Per-Arnt-Sim (PAS) domain protein, a novel type of hormone receptor. In higher flies like Drosophila, the ancestral receptor germ cell-expressed (gce) gene has duplicated to yield the paralog Methoprene-tolerant (Met). These paralogous receptors share redundant function during development but play unique roles in adults. Some aspects of JH function apparently require one receptor or the other. To provide a foundation for studying JH receptor function, we have recapitulated endogenous JH receptor expression with single cell resolution. Using Bacteria Artificial Chromosome (BAC) recombineering and a transgenic knock-in, we have generated a spatiotemporal expressional atlas of Met and gce throughout development. We demonstrate JH receptor expression in known JH target tissues, in which temporal expression corresponds with periods of hormone sensitivity. Larval expression largely supports the notion of functional redundancy. Furthermore, we provide the neuroanatomical distribution of JH receptors in both the larval and adult central nervous system, which will serve as a platform for future studies regarding JH action on insect behavior.
| S-EPMC5437021 | biostudies-literature
Project description:In Drosophila raised in nutrient-rich conditions, female body size is approximately 30% larger than male body size due to an increased rate of growth and differential weight loss during the larval period. While the mechanisms that control this sex difference in body size remain incompletely understood, recent studies suggest that the insulin/insulin-like growth factor signaling pathway (IIS) plays a role in the sex-specific regulation of processes that influence body size during development. In larvae, IIS activity differs between the sexes, and there is evidence of sex-specific regulation of IIS ligands. Yet, we lack knowledge of how changes to IIS activity impact body size in each sex, as the majority of studies on IIS and body size use single- or mixed-sex groups of larvae and/or adult flies. The goal of our current study was to clarify the body size requirement for IIS activity in each sex. To achieve this goal, we used established genetic approaches to enhance, or inhibit, IIS activity, and quantified pupal size in males and females. Overall, genotypes that inhibited IIS activity caused a female-biased decrease in body size, whereas genotypes that augmented IIS activity caused a male-specific increase in body size. These data extend our current understanding of body size regulation by showing that most changes to IIS pathway activity have sex-biased effects, and highlights the importance of analyzing body size data according to sex.
| S-EPMC8063079 | biostudies-literature
Project description:Background. Juvenile hormone (JH) has been demonstrated to control adult lifespan in a number of non-model insects where surgical removal of the corpora allata eliminates the source of hormone. In contrast, little is known about how juvenile hormone affects adult Drosophila melanogaster. Previous work suggests that insulin signaling may modulate Drosophila aging in part through its impact on juvenile hormone titer, but no data yet addresses whether reduction of juvenile hormone is sufficient to control Drosophila life span. Here we adapt a recent genetic approach to knock out the corpora allata in adult Drosophila melanogaster and characterize adult life history phenotypes produced by reduction of juvenile hormone. With this system we test potential explanations for how juvenile hormone modulates aging. Conclusions. Reduced juvenile hormone alone is sufficient to extend lifespan of Drosophila melanogaster. Reduced juvenile hormone limits reproduction by inhibiting the production of yolked eggs, and this may arise because juvenile hormone is required for the post-eclosion development of vitellogenin-producing adult fat body. Our data do not support a mechanism for juvenile hormone control of longevity simply based on reducing the physiological costs of reproductive. Nor does the longevity benefit appear to function through mechanisms by which dietary restriction extends longevity. We identify transcripts that change in response to juvenile hormone independent of reproductive state and suggest these represent somatically expressed genes that could modulate how juvenile hormone controls persistence and longevity. Four genotypes were analyzed. They are CA knockout (CAKO), wildtype (wDah/w1118 ), CAKO with OvoD1 mutation and control (wDah/w1118) with OvoD1 mutation. Three biological replicates for each genotype.
2013-07-26 | E-GEOD-48145 | biostudies-arrayexpress