Hormone-dependent activation and repression of microRNAs by the ecdysone receptor in the dengue vector mosquito Aedes aegypti

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.

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A COUP-TF/Svp homolog is highly expressed during vitellogenesis in the mosquito Aedes aegypti

Journal of Molecular Endocrinology ◽

10.1677/jme.0.0290223 ◽

2002 ◽

Vol 29 (2) ◽

pp. 223-238 ◽

Cited By ~ 22

Author(s):

K Miura ◽

J Zhu ◽

NT Dittmer ◽

L Chen ◽

AS Raikhel

Keyword(s):

Aedes Aegypti ◽

Blood Meal ◽

Fat Body ◽

Sequence Similarity ◽

Amino Acid Sequence Similarity ◽

Receptor Complex ◽

Ecdysone Receptor ◽

Ecdysteroid Receptor

In the mosquito Aedes aegypti, vitellogenesis is activated via an ecdysteroid hormonal cascade initiated by a blood meal. The functional ecdysone receptor is a heterodimer composed of the ecdysone receptor (EcR) and ultraspiracle, the homolog of the retinoid X receptor. The precise tuning of this hormonal response requires participation of both positive and negative transcriptional regulators. In Drosophila, Svp, a homolog of chicken ovalbumin upstream promoter transcription factor (COUP-TF), inhibits ecdysone receptor complex-mediated transactivation in vitro and in vivo. Here we report the cloning and characterization of the Svp homolog in mosquito Aedes aegypti, AaSvp. It possesses a high degree of amino acid sequence similarity to the members of the COUP-TF/Svp subfamily. AaSvp transcripts and protein are present in the fat body at high levels from the state of arrest to about 60 h post blood meal. AaSvp binds strongly to a variety of direct repeats of the sequence AGGTCA, but weakly to inverted repeats such as hsp27 EcRE. Transient transfection assays in Drosophila S2 cells showed that AaSvp was able to repress 20-hydroxyecdysone (20E)-dependent transactivation mediated by the mosquito ecdysteroid receptor complex. These data suggest that AaSvp negatively regulates the 20E signaling in the fat body during mosquito vitellogenesis.

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The Fat Body Transcriptomes of the Yellow Fever Mosquito Aedes aegypti, Pre- and Post- Blood Meal

PLoS ONE ◽

10.1371/journal.pone.0022573 ◽

2011 ◽

Vol 6 (7) ◽

pp. e22573 ◽

Cited By ~ 47

Author(s):

David P. Price ◽

Vijayaraj Nagarajan ◽

Alexander Churbanov ◽

Peter Houde ◽

Brook Milligan ◽

...

Keyword(s):

Aedes Aegypti ◽

Yellow Fever ◽

Blood Meal ◽

Fat Body ◽

Yellow Fever Mosquito

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Pathology of Coelomomyces stegomyiae in adult Aedes aegypti ovaries

Canadian Journal of Botany ◽

10.1139/b88-127 ◽

1988 ◽

Vol 66 (5) ◽

pp. 877-884 ◽

Cited By ~ 9

Author(s):

Christopher J. Lucarotti ◽

Marina B. Klein

Keyword(s):

Plasma Membrane ◽

Aedes Aegypti ◽

Adult Female ◽

Blood Meal ◽

Egg Development ◽

Yolk Granules ◽

Receptor Mediated Endocytosis ◽

Fungal Hyphae ◽

Tunica Propria ◽

Coelomomyces Stegomyiae

Coelomomyces stegomyiae (Chytridiomycetes, Blastocladiales) infection in adult female Aedes aegypti (Diptera, Culicidae) is located primarily in the ovaries. Fungal hyphae do not penetrate the germaria or follicles but instead lie between the tunica propria and epithelial sheath within each ovariole and between the epithelial sheath and the peritoneal sheath of the ovary. Aedes aegypti is an anautogenous mosquito requiring a blood meal for egg development; similarly, fungal hyphae in infected ovaries will not differentiate to form resting sporangia until after the mosquito has taken a blood meal. The fungus restricts receptor-mediated endocytosis of vitellogenin by the plasma membrane of the oocyte so that few, if any, vitellin yolk granules form. Thick-walled resting sporangia have formed 72 h after the blood meal has been taken and these will be oviposited by the females in place of the aborted eggs.

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The influence of the brain hormone on retention of blood in the mid-gut of the mosquito Aedes aegypti (L.) III. The involvement of the ovaries and ecdysone

Proceedings of the Royal Society of London Series B Biological Sciences ◽

10.1098/rspb.1979.0074 ◽

1979 ◽

Vol 205 (1160) ◽

pp. 411-421 ◽

Cited By ~ 11

Keyword(s):

Aedes Aegypti ◽

Blood Meal ◽

Ovarian Development ◽

Neurosecretory Cells ◽

Direct Result ◽

Corpus Cardiacum ◽

Egg Development ◽

The Brain

Most female mosquitoes require a blood-meal in order to produce mature oöcytes. An egg development neurosecretory hormone (EDNH), which is produced in the medial neurosecretory cells (m. n. c.) of the brain and stored in the corpus cardiacum, is released into the haemolymph following the ingestion of blood and is essential for the promotion of ovarian development to maturity. It has been shown that a factor from the m. n. c., presumably EDNH, is necessary if the blood-meal is to be retained in the mid-gut until the oöcytes approach maturity. The present paper shows that retention is not a direct result of the action of EDNH, but is dependent on the ovaries and may well involve ecdysone. Removal of the ovaries before a blood-meal leads to early haem-defaecation, but delay can be restored by injection of ecdysterone. Sub-threshold feeders and mosquitoes decapitated immediately after the intake of blood, each of which would be expected to eliminate the blood-meal early, also show a delay in the onset of haem-defaecation when injected with ecdysterone. Further, both in ovariectomized insects and sub-threshold feeders the time of onset of haem-defaecation is associated with the dose of ecdysterone given.

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On the use of inhibitors of 4-hydroxyphenylpyruvate dioxygenase as a vector-selective insecticide in the control of mosquitoes

10.1101/669747 ◽

2019 ◽

Author(s):

Marlon A. V. Ramirez ◽

Marcos Sterkel ◽

Ademir de Jesus Martins ◽

José Bento Pereira Lima ◽

Pedro L. Oliveira

Keyword(s):

Amino Acids ◽

Body Weight ◽

Aedes Aegypti ◽

Blood Meal ◽

Mosquito Control ◽

Blood Feeding ◽

Degradation Pathway ◽

Cross Resistance ◽

Single Meal ◽

Neurotoxic Insecticides

AbstractBlood-sucking insects incorporate many times their body weight of blood in a single meal. As proteins are the major component of vertebrate blood, its digestion in the gut of hematophagous insects generates extremely high concentrations of free amino acids. Previous reports showed that the tyrosine degradation pathway plays an essential role in adapting these animals to blood feeding. Inhibiting 4-hydroxyphenylpyruvate dioxygenase (HPPD), the rate-limiting step of tyrosine degradation, results in the death of insects after a blood meal. Therefore, it was suggested that compounds that block the catabolism of tyrosine could act selectively on blood-feeding insects. Here we have evaluated the toxicity against mosquitoes of three HPPD inhibitors currently used as herbicides and in human health. Among the compounds tested, nitisinone (NTBC) proved to be more potent than mesotrione (MES) and isoxaflutole (IFT) in Aedes aegypti. NTBC was lethal to Ae. aegypti in artificial feeding assays (LD50: 4.36 µM), as well as in topical application (LD50: 0.0033 nmol/mosquito). NTBC was also lethal to Ae. aegypti populations that were resistant to neurotoxic insecticides, and it was lethal to other mosquito species (Anopheles and Culex). Therefore, HPPD inhibitors, particularly NTBC, represent promising new drugs for mosquito control. Since they only affect blood-feeding organisms, they would represent a safer and more environmentally friendly alternative to conventional neurotoxic insecticides.Author SummaryThe control of mosquitoes has been pursued in the last decades by the use of neurotoxic insecticides to prevent the spreading of dengue, zika and malaria, among other diseases. However, the selection and propagation of different mechanisms of resistance hinder the success of these compounds. New methodologies are needed for their control. Hematophagous arthropods, including mosquitoes, ingest quantities of blood that represent many times their body weight in a single meal, releasing huge amounts of amino acids during digestion. Recent studies showed that inhibition of the tyrosine catabolism pathway could be a new selective target for vector control. Thus we tested three different inhibitors of the second enzyme in the tyrosine degradation pathway as tools for mosquito control. Results showed that Nitisinone (NTBC), an inhibitor used in medicine, was the most potent of them. NTBC was lethal to Aedes aegypti when it was administered together with the blood meal and when it was topically applied. It also caused the death of Anopheles aquasalis and Culex quinquefasciatus mosquitoes, as well as field-collected Aedes populations resistant to neurotoxic insecticides, indicating that there is no cross-resistance. We discuss the possible use of NTBC as a new insecticide.

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The juvenile hormone receptor Methoprene-tolerant is involved in the sterilizing effect of pyriproxyfen on adult Aedes aegypti mosquitoes

10.1101/2020.05.31.126508 ◽

2020 ◽

Author(s):

Tahmina Hossain Ahmed ◽

T. Randolph Saunders ◽

Donald Mullins ◽

Mohammad Zillur Rahman ◽

Jinsong Zhu

Keyword(s):

Aedes Aegypti ◽

Juvenile Hormone ◽

Mosquito Control ◽

Fat Body ◽

Control Strategies ◽

Follicular Development ◽

Blood Feeding ◽

Oocyte Development ◽

Hormonal Responses ◽

Before And After

AbstractExposure of adult mosquitoes to pyriproxyfen (PPF), an analog of insect juvenile hormone (JH), has shown promise to effectively sterilize female mosquitoes. However, the underlying mechanisms of the PPF-induced decrease in mosquito fecundity are largely unknown. We performed a comprehensive study to dissect the mode of PPF action in Aedes aegypti mosquitoes. Exposure to PPF prompted the overgrowth of primary follicles in sugar-fed Ae. aegypti females but blocked the development of primary follicles at Christopher’s Stage III after blood feeding. Secondary follicles were precociously activated in PPF-treated mosquitoes. Moreover, PPF substantially altered the expression of many genes that are essential for mosquito physiology and oocyte development in the fat body and ovary. In particular, many metabolic genes were differentially expressed in response to PPF treatment, thereby affecting the mobilization and utilization of energy reserves. Furthermore, PPF treatment on the previtellogenic female adults considerably modified mosquito responses to JH and 20-hydroxyecdysone (20E), two major hormones that govern mosquito reproduction. Krüppel homolog 1, a JH-inducible transcriptional regulator, showed consistently elevated expression after PPF exposure. Conversely, PPF upregulated the expression of several key players of the 20E regulatory cascades, including HR3 and E75A, in the previtellogenic stage. After blood-feeding, the expression of these 20E response genes was significantly weaker in PPF-treated mosquitoes than the solvent-treated control groups. RNAi-mediated knockdown of the Methoprene-tolerant (Met) protein, the JH receptor, partially rescued the impaired follicular development after PPF exposure and substantially increased the hatching of the eggs produced by PPF-treated female mosquitoes. Thus, the results suggested that PPF relied on Met to exert its sterilizing effects on female mosquitoes. In summary, this study finds that PPF exposure disturbs normal hormonal responses and metabolism in Ae. aegypti, shedding light on the molecular targets and the downstream signaling pathways activated by PPF.Author summaryAedes aegypti mosquitoes are responsible for the transmission of dengue, yellow fever, chikungunya, and Zika fever. Insecticides are widely used as the primary tool in the prevention and control of these infectious diseases. In light of the rapid increase of insecticide resistance in mosquito populations, there is an urgent need to find new classes of insecticides with a different mode of action. Here we found that pyriproxyfen, an analog of insect juvenile hormone (JH), had a large impact on the oocyte development, both before and after blood feeding, in female mosquitoes. Pyriproxyfen disturbed normal hormonal responses and caused metabolic shifting in female adults. These actions appear to collectively impair oocyte development and substantially reduce viable progenies of female mosquitoes. Besides, we demonstrated the involvement of the JH receptor Met in pyriproxyfen-induced female sterilization. This study significantly advances our understanding of mosquito reproductive biology and the molecular basis of pyriproxyfen action, which are invaluable for the development of new mosquito control strategies.

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Mating and blood-feeding induce transcriptome changes in the spermathecae of the yellow fever mosquito Aedes aegypti

Scientific Reports ◽

10.1038/s41598-020-71904-z ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Carolina Camargo ◽

Yasir H. Ahmed-Braimah ◽

I. Alexandra Amaro ◽

Laura C. Harrington ◽

Mariana F. Wolfner ◽

...

Keyword(s):

Aedes Aegypti ◽

Blood Meal ◽

Transcriptional Response ◽

Blood Feeding ◽

Sperm Storage ◽

Biological Processes ◽

Gene Products ◽

Heme Peroxidase ◽

Males And Females

Abstract Aedes aegypti mosquitoes are the primary vectors of numerous viruses that impact human health. As manipulation of reproduction has been proposed to suppress mosquito populations, elucidation of biological processes that enable males and females to successfully reproduce is necessary. One essential process is female sperm storage in specialized structures called spermathecae. Aedes aegypti females typically mate once, requiring them to maintain sperm viably to fertilize eggs they lay over their lifetime. Spermathecal gene products are required for Drosophila sperm storage and sperm viability, and a spermathecal-derived heme peroxidase is required for long-term Anopheles gambiae fertility. Products of the Ae. aegypti spermathecae, and their response to mating, are largely unknown. Further, although female blood-feeding is essential for anautogenous mosquito reproduction, the transcriptional response to blood-ingestion remains undefined in any reproductive tissue. We conducted an RNAseq analysis of spermathecae from unfed virgins, mated only, and mated and blood-fed females at 6, 24, and 72 h post-mating and identified significant differentially expressed genes in each group at each timepoint. A blood-meal following mating induced a greater transcriptional response in the spermathecae than mating alone. This study provides the first view of elicited mRNA changes in the spermathecae by a blood-meal in mated females.

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The early gene Broad is involved in the ecdysteroid hierarchy governing vitellogenesis of the mosquito Aedes aegypti

Journal of Molecular Endocrinology ◽

10.1677/jme.1.01531 ◽

2004 ◽

Vol 33 (3) ◽

pp. 743-761 ◽

Cited By ~ 42

Author(s):

L Chen ◽

J Zhu ◽

G Sun ◽

A S Raikhel

Keyword(s):

Aedes Aegypti ◽

Fat Body ◽

Regulatory Region ◽

Blood Feeding ◽

Early Gene ◽

Gene Encoding ◽

Obvious Effect ◽

Early Genes ◽

Old Females

The broad (br ) gene, encoding a family of C2H2 type zinc-finger DNA-binding proteins, has been shown to act as a crucial member of the 20-hydroxyecdysone (20E) regulatory hierarchy in the fruitfly, Drosophila melanogaster and the moth, Manduca sexta. In this study, we have shown that the br gene is involved in the 20E-regulatory hierarchy controlling vitellogenesis in the mosquito, Aedes aegypti. Unlike E74 and E75 early genes, expression of br was activated in previtellogenic females, during a juvenile hormone (JH)-dependent period. The levels of Z1, Z2 and Z4 isoform mRNA were elevated in the fat body of 2-day-old females after in vitro exposure to JH III. However, JH III repressed 20E activation of br in 3-to 5-day-old females, indicating a switch in hormonal commitment. Expression of Z1, Z2 and Z4 was stimulated after blood feeding in both vitellogenic tissues, the fat body and the ovary, corresponding to peaks of ecdysteroid titers. In the fat body, the mRNA profiles of these three isoforms correlated well with those of yolk protein precursor (YPP) genes. These BR isoforms were activated by 20E in fat bodies cultured in vitro and behaved as early genes, with a self-repressive autoregulatory loop that can be blocked by the protein inhibitor, cyclohexamide. Multiple binding sites for all four BR isoforms were present in the 5′-regulatory region of the major YPP gene, vitellogenin (Vg). Effects of BR isoforms on the expression of Vg have been demonstrated by cell transfection analysis. In particular, BR isoforms by themselves had no effects on the Vg promoter. However, Z1 and Z4 each repressed Aedes aegypti ecdysone receptor (EcR)/Ultraspiracle (USP)-mediated 20E activation of the Vg promoter, while Z2 enhanced activation of the Vg promoter by AaEcR/AaUSP in the presence of 20E. Z3 had no obvious effect in the same experiment. These results suggested that BR isoforms are essential for proper activation and termination of the Vg gene in response to 20E. Overall, our study implicated br in the regulation of mosquito vitellogenesis.

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Human blood microRNA hsa-miR-21-5p induces vitellogenin in the mosquito Aedes aegypti

Communications Biology ◽

10.1038/s42003-021-02385-7 ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Hugo D. Perdomo ◽

Mazhar Hussain ◽

Rhys Parry ◽

Kayvan Etebari ◽

Lauren M. Hedges ◽

...

Keyword(s):

Aedes Aegypti ◽

Human Blood ◽

Egg Production ◽

Fat Body ◽

Blood Feeding ◽

Mosquito Vectors ◽

Progeny Production ◽

Proteomics Analysis ◽

Gene Coding ◽

Reproductive Events

AbstractMosquito vectors transmit various diseases through blood feeding, required for their egg development. Hence, blood feeding is a major physiological event in their life cycle, during which hundreds of genes are tightly regulated. Blood is a rich source of proteins for mosquitoes, but also contains many other molecules including microRNAs (miRNAs). Here, we found that human blood miRNAs are transported abundantly into the fat body tissue of Aedes aegypti, a key metabolic center in post-blood feeding reproductive events, where they target and regulate mosquito genes. Using an artificial diet spiked with the mimic of an abundant and stable human blood miRNA, hsa-miR-21-5p, and proteomics analysis, we found over 40 proteins showing differential expression in female Ae. aegypti mosquitoes after feeding. Of interest, we found that the miRNA positively regulates the vitellogenin gene, coding for a yolk protein produced in the mosquito fat body and then transported to the ovaries as a protein source for egg production. Inhibition of hsa-miR-21-5p followed by human blood feeding led to a statistically insignificant reduction in progeny production. The results provide another example of the involvement of small regulatory molecules in the interaction of taxonomically vastly different taxa.

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Novel small molecule agonists of an Aedes aegypti neuropeptide Y receptor block mosquito biting behavior

10.1101/393793 ◽

2018 ◽

Cited By ~ 2

Author(s):

Laura B. Duvall ◽

Lavoisier Ramos-Espiritu ◽

Kyrollos E. Barsoum ◽

J. Fraser Glickman ◽

Leslie B. Vosshall

Keyword(s):

Aedes Aegypti ◽

Neuropeptide Y ◽

Small Molecule ◽

Blood Meal ◽

Disease Transmission ◽

Blood Feeding ◽

Behavioral Suppression ◽

Host Seeking ◽

Novel Approach ◽

Seeking Behavior

AbstractFemale Aedes aegypti mosquitoes bite humans to obtain a blood-meal to develop their eggs. Remarkably, strong attraction to humans is suppressed for several days after the blood-meal by an unknown mechanism. We investigated a role for neuropeptide Y (NPY)-related signaling in this long-term behavioral suppression, and discovered that drugs targeting human NPY receptors modulate mosquito host-seeking behavior. In a screen of all 49 predicted Ae. aegypti peptide receptors, we identified NPY-like receptor 7 (NPYLR7) as the sole target of these human drugs. To obtain small molecule agonists selective for NPYLR7, we carried out a high-throughput cell-based assay of 265,211 compounds, and isolated 6 highly selective NPYLR7 agonists that inhibit mosquito attraction to humans. NPYLR7 CRISPR-Cas9 null mutants are defective in behavioral suppression, and resistant to these drugs. Finally, we show that these drugs are capable of inhibiting biting and blood-feeding on a live host, suggesting a novel approach to control infectious disease transmission by controlling mosquito behavior.

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