Direct and indirect gene repression by the ecdysone cascade during mosquito reproductive cycle.
Ontology highlight
ABSTRACT:
SUBMITTER: Roy S
PROVIDER: S-EPMC8931382 | biostudies-literature | 2022 Mar
REPOSITORIES: biostudies-literature
Publications
Direct and indirect gene repression by the ecdysone cascade during mosquito reproductive cycle.
Roy Sourav S Saha Tusar T TT Ha Jisu J Banerjee Roumik R Aksoy Emre E Kulkarni Aditi A Raikhel Alexander S AS
Proceedings of the National Academy of Sciences of the United States of America 20220307 11
SignificanceHematophagous <i>Aedes aegypti</i> mosquitoes spread devastating viral diseases. Upon blood feeding, a steroid hormone, 20-hydroxyecdysone (20E), initiates a reproductive program during which thousands of genes are differentially expressed. While 20E-mediated gene activation is well known, repressive action by this hormone remains poorly understood. Using bioinformatics and molecular biological approaches, we have identified the mechanisms of 20E-dependent direct and indirect transcr ...[more]
Similar Datasets
Project description:Female mosquitoes transmit numerous devastating human diseases because they require vertebrate blood meal for egg development. MicroRNAs (miRNAs) play critical roles across multiple reproductive processes in female Aedes aegypti mosquitoes. However, how miRNAs are controlled to coordinate their activity with the demands of mosquito reproduction remains largely unknown. We report that the ecdysone receptor (EcR)-mediated 20-hydroxyecdysone (20E) signaling regulates miRNA expression in female mosquitoes. EcR RNA-interference silencing linked to small RNA-sequencing analysis reveals that EcR not only activates but also represses miRNA expression in the female mosquito fat body, a functional analog of the vertebrate liver. EcR directly represses the expression of clustered miR-275 and miR-305 before blood feeding when the 20E titer is low, whereas it activates their expression in response to the increased 20E titer after a blood meal. Furthermore, we find that SMRTER, an insect analog of the vertebrate nuclear receptor corepressors SMRT and N-CoR, interacts with EcR in a 20E-sensitive manner and is required for EcR-mediated repression of miRNA expression in Ae. aegypti mosquitoes. In addition, we demonstrate that miR-275 and miR-305 directly target glutamate semialdehyde dehydrogenase and AAEL009899, respectively, to facilitate egg development. This study reveals a mechanism for how miRNAs are controlled by the 20E signaling pathway to coordinate their activity with the demands of mosquito reproduction.
| S-EPMC8256052 | biostudies-literature
Project description:BackgroundA good understanding of mosquito ecology is imperative for integrated vector control of malaria. In breeding sites, Anopheles larvae are concurrently exposed to predators and parasites. However, to our knowledge, there is no study on combined effects of predators and parasites on development and survival of larvae and their carry-over effects on adult survivorship and susceptibility to further parasite infection.MethodsThis study focused on effects of the nymphs of the dragonfly Pantala flavescens and the parasitic fungus Beauveria bassiana on Anopheles gambiae, to determine: predation efficacy of nymphs against An. gambiae larvae; development rate of An. gambiae larvae in the presence of one, two or four constrained nymphs; efficacy of B. bassiana against An. gambiae larvae at doses of 3, 6 and 12 mg; and survival of adult mosquitoes exposed to B. bassiana, following pre-exposure to a constrained predator and/or parasite at the larval stage. The experiments consisted of survival bioassays quantified as pupation day, or dead larvae and/or adults.ResultsNymphs had an average predation efficacy of 88.3% (95% CI: 87.5-89.1) at 24 hours, against An. gambiae larvae. The presence of one or two nymphs reduced development time of larvae by 0.65 and 0.35 days, respectively. However, development time of larvae exposed to four nymphs was similar to the control larvae. Larvae exposed to 3, 6 and 12 mg of B. bassiana were 2.0, 2.5 and 3.5 times more likely to die, respectively, compared to control larvae. Adults not pre-exposed, those pre-exposed to predator, parasite, or both were 45.8, 67.4, 50.9 and 112.0 times more likely to die, respectively, compared to control that were unexposed to predator or parasite, at larval and adult stage.ConclusionsThis study shows that both predator and parasite can reduce larval population of An. gambiae, and presence of predator cues decreases development time in breeding sites, as well as, increases the susceptibility of emerging adult to fungus. Predator and parasite both have an additive effect on survival of adults exposed to B. bassiana. Field studies are required for an in-depth understanding of predator and parasite influence on mosquito development time, survival and susceptibility in nature.
| S-EPMC6990496 | biostudies-literature
Project description:Runt-related transcription factor 1 (Runx1) can act as both an activator and a repressor. Here we show that CRISPR-mediated deletion of Runx1 in mouse metanephric mesenchyme-derived mK4 cells results in large-scale genome-wide changes to chromatin accessibility and gene expression. Open chromatin regions near down-regulated loci enriched for Runx sites in mK4 cells lose chromatin accessibility in Runx1 knockout cells, despite remaining Runx2-bound. Unexpectedly, regions near upregulated genes are depleted of Runx sites and are instead enriched for Zeb transcription factor binding sites. Re-expressing Zeb2 in Runx1 knockout cells restores suppression, and CRISPR mediated deletion of Zeb1 and Zeb2 phenocopies the gained expression and chromatin accessibility changes seen in Runx1KO due in part to subsequent activation of factors like Grhl2. These data confirm that Runx1 activity is uniquely needed to maintain open chromatin at many loci, and demonstrate that Zeb proteins are required and sufficient to maintain Runx1-dependent genome-scale repression.
| S-EPMC8219162 | biostudies-literature
Project description:The insulin signaling pathway is evolutionarily conserved throughout metazoans, playing key roles in development, growth, and metabolism. Misregulation of this pathway is associated with a multitude of disease states including diabetes, cancer, and neurodegeneration. Genome-wide association studies indicate that natural variants in putative intronic regulatory elements of the human insulin receptor gene ( INSR) are associated with metabolic conditions, however, this gene's transcriptional regulation remains incompletely studied. INSR is widely expressed throughout development and was previously described as a 'housekeeping' gene. Yet, there is abundant evidence that this gene is expressed in a cell-type specific manner, with dynamic regulation in response to environmental signals. The Drosophila insulin-like receptor gene ( InR ) is homologous to the human INSR gene and was previously shown to be regulated by multiple transcriptional elements located primarily within the introns of the gene. These elements were roughly defined in ∼1.5 kbp segments, but we lack an understanding of the potential detailed mechanisms of their regulation, as well as the integrative output of the battery of enhancers in the entire locus. Using luciferase assays, we characterized the substructure of these cis-regulatory elements in Drosophila S2 cells, focusing on regulation through the ecdysone receptor (EcR) and the dFOXO transcription factor. The direct action of EcR on Enhancer 2 reveals a bimodal form of regulation, with active repression in the absence of the ligand, and positive activation in the presence of 20E. By identifying the location of activators of this enhancer, we characterized a long-range of repression acting over at least 475 bp, similar to the action of long-range repressors found in the embryo. dFOXO and 20E have contrasting effects on some of the individual regulatory elements, and for the adjacent enhancers 2 and 3, their influence was/was not found to be additive, indicating that enhancer action on this locus can/cannot be characterized in part by additive models. Other characterized enhancers from within this locus exhibited "distributed" or "localized" modes of action, suggesting that predicting the joint functional output of multiple regulatory regions will require a deeper experimental characterization. The noncoding intronic regions of InR have demonstrated dynamic regulation of expression and cell type specificity. This complex transcriptional circuitry goes beyond the simple conception of a 'housekeeping' gene. Further studies are aimed at identifying how these elements work together in vivo to generate finely tuned expression in tissue- and temporal-specific manners, to provide a guide to understanding the impact of natural variation in this gene's regulation, applicable to human genetic studies.
| S-EPMC10245858 | biostudies-literature
Project description:Bone Morphogenetic Proteins (BMPs) signal by activating Smad transcription factors to control a number of decisions during animal development. In Drosophila, signaling by the BMP ligand Decapentaplegic (Dpp) involves the activity of brinker (brk) which, in most contexts, is repressed by Dpp. Brk encodes a transcription factor which represses BMP signaling output by antagonizing Smad-dependent target gene activation. Here, we study BMP-dependent gene regulation during Drosophila oogenesis by following the signal transmission from Dpp to its target broad (br), a gene with a crucial function in eggshell patterning. We identify regulatory sequences that account for expression of both brk and br, and connect these to the transcription factors of the pathway. We show that Dpp directly regulates brk transcription through Smad- and Schnurri (Shn)-dependent repression. Brk is epistatic to Dpp in br expression and activates br indirectly, through removal of a repressor, which is yet to be identified. Our work provides first cis-regulatory insights into transcriptional interpretation of BMP signaling in eggshell morphogenesis and defines a transcriptional cascade that connects Dpp to target gene regulation.
| S-EPMC4694571 | biostudies-literature
Project description:The role of REST changes in neurons, including the rapid decrease of its level during differentiation and its fluctuations during many mature functions and diseases, is well established. However, identification of many thousand possible REST-target genes, mostly based on indirect criteria, and demonstration of their operative dependence on the repressor have been established for only a relatively small fraction. In the present study, starting from our recently published work, we have expanded the identification of REST-dependent genes, investigated in two clones of the PC12 line, a recognized neuronal cell model, spontaneously expressing different levels of REST: very low as in neurons and much higher as in most non-neural cells. The molecular, structural and functional differences of the two PC12 clones were shown to depend largely on their different REST level and the ensuing variable expression of some dependent genes. Comprehensive RNA-Seq analyses of the 13,700 genes expressed, validated by parallel RT-PCR and western analyses of mRNAs and encoded proteins, identified in the high-REST clone two groups of almost 900 repressed and up-regulated genes. Repression is often due to direct binding of REST to target genes; up-regulation to indirect mechanism(s) mostly mediated by REST repression of repressive transcription factors. Most, but not all, genes governing neurosecretion, excitability, and receptor channel signaling were repressed in the high REST clone. The genes governing expression of non-channel receptors (G protein-coupled and others), although variably affected, were often up-regulated together with the genes of intracellular kinases, small G proteins, cytoskeleton, cell adhesion, and extracellular matrix proteins. Expression of REST-dependent genes governing functions other than those mentioned so far were also identified. The results obtained by the parallel investigation of the two PC12 clones revealed the complexity of the REST molecular and functional role, deciphering new aspects of its participation in neuronal functions. The new findings could be relevant for further investigation and interpretation of physiological processes typical of neurons. Moreover, they could be employed as tools in the study of neuronal diseases recently shown to depend on REST for their development.
| S-EPMC4639699 | biostudies-literature
Project description:Mitochondria are involved in ageing and their function requires coordinated action of both mitochondrial and nuclear genes. Epistasis between the two genomes can influence lifespan but whether this also holds for reproductive senescence is unclear. Maternal inheritance of mitochondria predicts sex differences in the efficacy of selection on mitonuclear genotypes that should result in differences between females and males in mitochondrial genetic effects. Mitonuclear genotype of a focal individual may also indirectly affect trait expression in the mating partner. We tested these predictions in the seed beetle Callosobruchus maculatus, using introgression lines harbouring distinct mitonuclear genotypes. Our results reveal both direct and indirect sex-specific effects of mitonuclear epistasis on reproductive ageing. Females harbouring coadapted mitonuclear genotypes showed higher lifetime fecundity due to slower senescence relative to novel mitonuclear combinations. We found no evidence for mitonuclear coadaptation in males. Mitonuclear epistasis not only affected age-specific ejaculate weight, but also influenced male age-dependent indirect effects on traits expressed by their female partners (fecundity, egg size, longevity). These results demonstrate important consequences of sex-specific mitonuclear epistasis for both mating partners, consistent with a role for mitonuclear genetic constraints upon sex-specific adaptive evolution.
| S-EPMC4751623 | biostudies-literature
Project description:The primary insect steroid hormone ecdysone requires a membrane transporter to enter its target cells. Although an organic anion-transporting polypeptide (OATP) named Ecdysone Importer (EcI) serves this role in the fruit fly Drosophila melanogaster and most likely in other arthropod species, this highly conserved transporter is apparently missing in mosquitoes. Here we report three additional OATPs that facilitate cellular incorporation of ecdysone in Drosophila and the yellow fever mosquito Aedes aegypti. These additional ecdysone importers (EcI-2, -3, and -4) are dispensable for development and reproduction in Drosophila, consistent with the predominant role of EcI. In contrast, in Aedes, EcI-2 is indispensable for ecdysone-mediated development, whereas EcI-4 is critical for vitellogenesis induced by ecdysone in adult females. Altogether, our results indicate unique and essential functions of these additional ecdysone importers in mosquito development and reproduction, making them attractive molecular targets for species- and stage-specific control of ecdysone signaling in mosquitoes.
| S-EPMC9231622 | biostudies-literature
Project description:The blood-feeding behavior of Anopheles females delivers essential nutrients for egg development and drives parasite transmission between humans. Plasmodium growth is adapted to the vector reproductive cycle, but how changes in the reproductive cycle impact parasite development remains unclear. Here, we show that the bloodmeal-induced miR-276-5p fine-tunes the expression of branched-chain amino acid transferase to terminate the reproductive cycle. Silencing of miR-276 prolongs high rates of amino acid (AA) catabolism and increases female fertility, suggesting that timely termination of AA catabolism restricts mosquito investment into reproduction. Prolongation of AA catabolism in P. falciparum-infected females also compromises the development of the transmissible sporozoite forms. Our results suggest that Plasmodium sporogony exploits the surplus mosquito resources available after reproductive investment and demonstrate the crucial role of the mosquito AA metabolism in within-vector parasite proliferation and malaria transmission.
| S-EPMC6904670 | biostudies-literature
Project description:Pregnancy rate is a major determinant of population dynamics of wild ungulates and of productivity of livestock systems. Allocation of feeding resources, including stocking rates, prior to and during the breeding season is a crucial determinant of this vital rate. Thus, quantification of effects and interaction among multiple factors that affect pregnancy rate is essential for management and conservation of pasture-based systems. Pregnancy rate of 2982 heifers and primiparous cows was studied as a function of animal category, average daily gain during the breeding season, stocking rate, pasture type and body weight at the beginning of the breeding season. Data were obtained from 43 experiments conducted in commercial ranches and research stations in the Pampas region between 1976 and 2015. Stocking rate ranged from 200 to 464 kg live weight ha-1, which brackets values for most of the grazinglands in similar regions. Age at breeding was 14-36 months (24.6±7.5 months); initial breeding weights were 129-506 kg and 194-570 kg for heifers and primiparous cows. Pregnancy rate was modeled with an apriori set of explanatory variables where proximate variables (breed, body weight at start of breeding, weight gain during breeding and category) were included first and subsequently modeled as functions of other variables (pasture type, supplementation and stocking rate). This modeling approach allowed detection of direct and indirect effects (through nutrition and body weight) of factors that affect pregnancy rate. Bos taurus breeds (N = 1058) had higher pregnancy rate than B. Taurus x B. indicus crossbreed (N = 1924) females. Pregnancy rate of heifers and primiparous cows grazing in natural grasslands decreased with increasing stocking rate, but no effect of stocking rate was detected in cultivated and improved pastures. Pregnancy rate increased with increasing average daily gain during the breeding season. Use of cultivated or improved natural pastures promotes higher pregnancy rate, as well as allows an increase in stocking rate at the regional level. Body weight at the start of the breeding season is the primary determinant of pregnancy rates in heifer and primiparous cows.
| S-EPMC9531839 | biostudies-literature