Review

Authors: Clive A Henrick

A brief overview is presented of the discovery and development of s-methoprene and some other juvenile hormone mimics. The identification of the natural juvenile hormones is described along with an outline of the part they play in the hormonal control of insect development. The properties and commercial applications of s-methoprene are presented with emphasis on its use in mosquito control and its minimal impact on the environment.

Topics: Animals; Culicidae; Methoprene; Molecular Structure; Mosquito Control; Pest Control, Biological

PubMed: 17853608
DOI: 10.2987/8756-971X(2007)23[225:M]2.0.CO;2

Review

Authors: Scott A Keith

Endocrine signaling networks control diverse biological processes and life history traits across metazoans. In both invertebrate and vertebrate taxa, steroid hormones regulate immune system function in response to intrinsic and environmental stimuli, such as microbial infection. The mechanisms of this endocrine-immune regulation are complex and constitute an ongoing research endeavor facilitated by genetically tractable animal models. The 20-hydroxyecdysone (20E) is the major steroid hormone in arthropods, primarily studied for its essential role in mediating developmental transitions and metamorphosis; 20E also modulates innate immunity in a variety of insect taxa. This review provides an overview of our current understanding of 20E-mediated innate immune responses. The prevalence of correlations between 20E-driven developmental transitions and innate immune activation are summarized across a range of holometabolous insects. Subsequent discussion focuses on studies conducted using the extensive genetic resources available in Drosophila that have begun to reveal the mechanisms underlying 20E regulation of immunity in the contexts of both development and bacterial infection. Lastly, I propose directions for future research into 20E regulation of immunity that will advance our knowledge of how interactive endocrine networks coordinate animals' physiological responses to environmental microbes.

Topics: Animals; Drosophila melanogaster; Gene Expression Regulation, Developmental; Steroids; Drosophila; Immunity, Innate; Juvenile Hormones; Ecdysterone; Metamorphosis, Biological

PubMed: 37319172
DOI: 10.1371/journal.pgen.1010782

Authors: Xiaoli Jin, Xiaoyan Wu, Lanting Zhou...

20-Hydroxyecdysone (20-HE) plays essential roles in coordinating developmental transitions of insects through responsive protein-coding genes and microRNAs (miRNAs). The involvement of single miRNAs in the ecdysone-signalling pathways has been extensively explored, but the interplay between ecdysone and the majority of miRNAs still remains largely unknown. Here, by small RNA sequencing, we systematically investigated the genome-wide responses of miRNAs to 20-HE in the embryogenic cell lines of and . Over 60 and 70 20-HE-responsive miRNAs were identified in the BmE cell line and S2 cell line, respectively. The response of miRNAs to ecdysone exhibited a time-dependent pattern, and the response intensity increased with extending exposure to 20-HE. The relationship between ecdysone and the miRNAs was further explored through knockdown of ecdysone-signalling pathway genes. Specifically, ecdysone regulated the cluster miR-275 and miR-305 through the coordination of and downstream , and the interaction between and miR-275 cluster was strengthened by the feedback regulation of . Ecdysone induced miR-275-3p and miR-305-5p through the ecdysone response effectors (EcREs) at the upstream of the pre-miR-275 cluster. Overall, the results might help us further understand the relationship between ecdysone signalling pathways and small RNAs in the development and metamorphosis of insects.

Topics: Animals; Biomarkers; Cell Line; Drosophila; Ecdysterone; Gene Expression Regulation; Insect Hormones; Insecta; Larva; MicroRNAs; Multigene Family; Response Elements; Signal Transduction; Time Factors

PubMed: 32482109
DOI: 10.1080/15476286.2020.1775395

Review

Authors: W S Bowers

The hormonal control of moulting, reproduction, and diapause in insects has little or no relationship to any similar phenomena in other animals, and the hormones involved in these processes are unlike any known hormones of vertebrates.The availability of pure chemicals with high biological activity has permitted an astonishing increase in research on insect hormones. At present, understanding of insect endocrinology is far too incomplete to justify much speculation about the possibility of using insect hormones as insecticides. However, the preliminary studies discussed in this paper give reason for hope, and the results justify further effort.

Topics: Alkynes; Animals; Chemical Phenomena; Chemistry; Coleoptera; Diet; Dioxoles; Drug Synergism; Ecdysone; Ethers; Fumigation; Insecta; Insecticides; Juvenile Hormones; Larva; Terpenes

PubMed: 4938025
DOI: No ID Found

Authors: Graeme J Roch, Nancy M Sherwood

The cystine knot growth factor (CKGF) superfamily includes important secreted developmental regulators, including the families of transforming growth factor beta, nerve growth factor, platelet-derived growth factor, and the glycoprotein hormones (GPHs). The evolutionary origin of the GPHs and the related invertebrate bursicon hormone, and their characteristic receptors, contributes to an understanding of the endocrine system in metazoans. Using a sensitive search method with hidden Markov models, we identified homologs of the hormones and receptors, along with the closely related bone morphogenetic protein (BMP) antagonists in basal metazoans. In sponges and a comb jelly, cystine knot hormones (CKHs) with mixed features of GPHs, bursicon, and BMP antagonists were identified using primary sequence and phylogenetic analysis. Also, we identified potential receptors for these CKHs, leucine-rich repeat-containing G protein-coupled receptors (LGRs), in the same species. Cnidarians, such as the sea anemone, coral, and hydra, diverged later in metazoan evolution and appear to have duplicated and differentiated CKH-like peptides resulting in bursicon/GPH-like peptides and several BMP antagonists: Gremlin (Grem), sclerostin domain containing (SOSD), neuroblastoma suppressor of tumorigenicity 1 (NBL1), and Norrie disease protein. An expanded cnidarian LGR group also evolved, including receptors for GPH and bursicon. With the appearance of bilaterians, a separate GPH (thyrostimulin) along with bursicon and BMP antagonists were present. Synteny indicates that the GPHs, Grem, and SOSD have been maintained in a common gene neighborhood throughout much of metazoan evolution. The stable and highly conserved CKGFs are not identified in nonmetazoan organisms but are established with their receptors in the basal metazoans, becoming critical to growth, development, and regulation in all animals.

Topics: Amino Acid Sequence; Animals; Evolution, Molecular; Follicle Stimulating Hormone; Glycoproteins; Humans; Intercellular Signaling Peptides and Proteins; Invertebrate Hormones; Molecular Sequence Data; Phylogeny; Receptors, G-Protein-Coupled; Sequence Alignment

PubMed: 24904013
DOI: 10.1093/gbe/evu118

Review

Authors: Mark R Brown, Douglas H Sieglaff, Huw H Rees...

Ecdysteroids are multifunctional hormones in male and female arthropods and are stored in oocytes for use during embryogenesis. Ecdysteroid biosynthesis and its hormonal regulation are demonstrated for insect gonads, but not for the gonads of other arthropods. The Y-organ in the cephalothorax of crustaceans and the integument of ticks are sources of secreted ecdysteroids in adults, as in earlier stages, but the tissue source is not known for adults in many arthropod groups. Ecdysteroid metabolism occurs in several tissues of adult arthropods. This review summarizes the evidence for ecdysteroid biosynthesis by gonads and its metabolism in adult arthropods and considers the apparent uniqueness of ecdysteroid hormones in arthropods, given the predominance of vertebrate-type steroids in sister invertebrate groups and vertebrates.

Topics: Animals; Arthropods; Ecdysteroids; Gonads

PubMed: 18680437
DOI: 10.1146/annurev.ento.53.103106.093334

Review

Authors: D Zitnan, Y-J Kim, I Zitnanová...

Insect ecdysis sequence is composed of pre-ecdysis, ecdysis and post-ecdysis behaviors controlled by a complex cascade of peptide hormones from endocrine Inka cells and neuropeptides in the central nervous system (CNS). Inka cells produce pre-ecdysis and ecdysis triggering hormones (ETH) which activate the ecdysis sequence through receptor-mediated actions on specific neurons in the CNS. Multiple experimental approaches have been used to determine mechanisms of ETH expression and release from Inka cells and its action on the CNS of moths and flies. During the preparatory phase 1-2 days prior to ecdysis, high ecdysteroid levels induce expression of ETH receptors in the CNS and increased ETH production in Inka cells, which coincides with expression of nuclear ecdysone receptor (EcR) and transcription factor cryptocephal (CRC). However, high ecdysteroid levels prevent ETH release from Inka cells. Acquisition of Inka cell competence to release ETH requires decline of ecdysteroid levels and beta-FTZ-F1 expression few hours prior to ecdysis. The behavioral phase is initiated by ETH secretion into the hemolymph, which is controlled by two brain neuropeptides-corazonin and eclosion hormone (EH). Corazonin acts on its receptor in Inka cells to elicit low level ETH secretion and initiation of pre-ecdysis, while EH induces cGMP-mediated ETH depletion and consequent activation of ecdysis. The activation of both behaviors is accomplished by ETH action on central neurons expressing ETH receptors A and B (ETHR-A and B). These neurons produce numerous excitatory or inhibitory neuropeptides which initiate or terminate different phases of the ecdysis sequence. Our data indicate that insect ecdysis is a very complex process characterized by two principal steps: (1) ecdysteroid-induced expression of receptors and transcription factors in the CNS and Inka cells. (2) Release and interaction of Inka cell peptide hormones and multiple central neuropeptides to control consecutive phases of the ecdysis sequence.

Topics: Amino Acid Sequence; Animals; Ecdysteroids; Insect Hormones; Molecular Sequence Data; Molting; Neuropeptides; Receptors, Neuropeptide; Receptors, Peptide; Receptors, Steroid; Sequence Homology, Amino Acid; Signal Transduction; Transcription Factors

PubMed: 17507015
DOI: 10.1016/j.ygcen.2007.04.002

Review

Authors: Hsiang-Yin Chen, Jean-Yves Toullec, Chi-Ying Lee...

Early studies recognizing the importance of the decapod eyestalk in the endocrine regulation of crustacean physiology-molting, metabolism, reproduction, osmotic balance, etc.-helped found the field of crustacean endocrinology. Characterization of putative factors in the eyestalk using distinct functional bioassays ultimately led to the discovery of a group of structurally related and functionally diverse neuropeptides, crustacean hyperglycemic hormone (CHH), molt-inhibiting hormone (MIH), gonad-inhibiting hormone (GIH) or vitellogenesis-inhibiting hormone (VIH), and mandibular organ-inhibiting hormone (MOIH). These peptides, along with the first insect member (ion transport peptide, ITP), constitute the original arthropod members of the crustacean hyperglycemic hormone (CHH) superfamily. The presence of genes encoding the CHH-superfamily peptides across representative ecdysozoan taxa has been established. The objective of this review is to, aside from providing a general framework, highlight the progress made during the past decade or so. The progress includes the widespread identification of the CHH-superfamily peptides, in particular in non-crustaceans, which has reshaped the phylogenetic profile of the superfamily. Novel functions have been attributed to some of the newly identified members, providing exceptional opportunities for understanding the structure-function relationships of these peptides. Functional studies are challenging, especially for the peptides of crustacean and insect species, where they are widely expressed in various tissues and usually pleiotropic. Progress has been made in deciphering the roles of CHH, ITP, and their alternatively spliced counterparts (CHH-L, ITP-L) in the regulation of metabolism and ionic/osmotic hemostasis under (eco)physiological, developmental, or pathological contexts, and of MIH in the stimulation of ovarian maturation, which implicates it as a regulator for coordinating growth (molt) and reproduction. In addition, experimental elucidation of the steric structure and structure-function relationships have given better understanding of the structural basis of the functional diversification and overlapping among these peptides. Finally, an important finding was the first-ever identification of the receptors for this superfamily of peptides, specifically the receptors for ITPs of the silkworm, which will surely give great impetus to the functional study of these peptides for years to come. Studies regarding recent progress are presented and synthesized, and prospective developments remarked upon.

Topics: Animals; Arthropod Proteins; Crustacea; Invertebrate Hormones; Multigene Family; Nerve Tissue Proteins

PubMed: 33117290
DOI: 10.3389/fendo.2020.578958

Review

Authors: Tom Levy, Amir Sagi

The androgenic gland (AG)-a unique crustacean endocrine organ that secretes factors such as the insulin-like androgenic gland (IAG) hormone-is a key player in crustacean sex differentiation processes. IAG expression induces masculinization, while the absence of the AG or a deficiency in IAG expression results in feminization. Therefore, by virtue of its universal role as a master regulator of crustacean sexual development, the IAG hormone may be regarded as the sexual "IAG-switch." The switch functions within an endocrine axis governed by neuropeptides secreted from the eyestalks, and interacts downstream with specific insulin receptors at its target organs. In recent years, IAG hormones have been found-and sequenced-in dozens of decapod crustacean species, including crabs, prawns, crayfish and shrimps, bearing different types of reproductive strategies-from gonochorism, through hermaphroditism and intersexuality, to parthenogenesis. The IAG-switch has thus been the focus of efforts to manipulate sex developmental processes in crustaceans. Most sex manipulations were performed using AG ablation or knock-down of the gene in males in order to sex reverse them into "neo-females," or using AG implantation/injecting AG extracts or cells into females to produce "neo-males." These manipulations have highlighted the striking crustacean sexual plasticity in different species and have permitted the manifestation of either maleness or femaleness without altering the genotype of the animals. Furthermore, these sex manipulations have not only facilitated fundamental studies of crustacean sexual mechanisms, but have also enabled the development of the first IAG-switch-based monosex population biotechnologies, primarily for aquaculture but also for pest control. Here, we review the crustacean IAG-switch, a unique crustacean endocrine mechanism, from the early discoveries of the AG and the IAG hormone to recent IAG-switch-based manipulations. Moreover, we discuss this unique early pancrustacean insulin-based sexual differentiation control mechanism in contrast to the extensively studied mechanisms in vertebrates, which are based on sex steroids.

Topics: Animals; Arthropod Proteins; Decapoda; Endocrine System; Insulin; Invertebrate Hormones; Sex Differentiation; Signal Transduction

PubMed: 33013714
DOI: 10.3389/fendo.2020.00651

Authors: Fabian O Ramos, Marcela Nouzova, Leonardo L Fruttero...

Juvenile hormone (JH) signalling, via its receptor Methoprene-tolerant (Met), controls metamorphosis and reproduction in insects. Met belongs to a superfamily of transcription factors containing the basic Helix Loop Helix (bHLH) and Per Arnt Sim (PAS) domains. Since its discovery in 1986, Met has been characterized in several insect species. However, in spite of the importance as vectors of Chagas disease, our knowledge on the role of Met in JH signalling in Triatominae is limited. In this study, we cloned and sequenced the Dipetalogaster maxima Met transcript (DmaxMet). Molecular modelling was used to build the structure of Met and identify the JH binding site. To further understand the role of the JH receptor during oogenesis, transcript levels were evaluated in two main target organs of JH, fat body and ovary. Functional studies using Met RNAi revealed significant decreases of transcripts for vitellogenin (Vg) and lipophorin (Lp), as well as their receptors. Lp and Vg protein amounts in fat body, as well as Vg in hemolymph were also decreased, and ovarian development was impaired. Overall, these studies provide additional molecular insights on the roles of JH signalling in oogenesis in Triatominae; and therefore are relevant for the epidemiology of Chagas´ disease.

Topics: Animals; Female; Juvenile Hormones; Methoprene; Oogenesis; Triatominae; Vitellogenins

PubMed: 35988007
DOI: 10.1038/s41598-022-18384-5