ecdysterone

..Finally, we show that GAL4-EcR functions as a potent and specific dominant negative at the onset of metamorphosis, providing a new tool for characterizing ecdysteroid signaling pathways during development...

..Cells within all lymph gland lobes, including prohemocytes from posterior lobes, massively differentiate into a new cell type specifically devoted to encapsulation, the lamellocyte...

..They also provide evidence that additional flanking regulatory sequences are crucially required to potentiate the hormonal response mediated by both types of elements and specify its spatial and temporal pattern...

..These results implicate 20E in enhancing axonal outgrowth of Kenyon cells to support MB remodeling during metamorphosis...

..In the present review, the distribution, biosynthesis, biological significance and potential applications of phytoecdysteroids are summarised...

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..These data suggest that Hsc70 participates in the 20E signal transduction pathway via binding to USP1 and mediating the expression of EcRB1, USP1 and then a set of 20E-responsive genes...

..Identification of the in vivo USP phosphorylation sites and signal transduction pathways that regulate the specific USP phosphorylation is currently underway...

We have determined the molecular organization of an ecdysterone-responsive puff site in Drosophila melanogaster. The 71E puff site contains a tightly linked cluster of at least seven genes within a neighborhood of 10 X 10(3) base-pairs...

..These results demonstrated that ecdysone could function as a bona fide ligand in a species-specific manner...

..This system permits the study of neuronal death in response to its bona fide developmental signal, the rise in a steroid hormone...

A synthetic, 23-bp ecdysterone regulatory element (EcRE), derived from the upstream region of the Drosophila melanogaster hsp27 gene, was inserted adjacent to the herpes simplex virus thymidine kinase promoter fused to a bacterial gene ..

..This review surveys the recent characterization of these ecdysone-inducible genes and provides an overview of how they expand our understanding of ecdysone functions during development...

..Aside from being involved in the control of decisions during embryonic development, fkh thus participates directly in the control of specialized functions of differentiated cells at later stages of development...

..Whereas EcR-USP DNA-binding activity is unaffected by hormone, EcR-RXR DNA-binding activity is stimulated by either ecdysteroid or 9-cis-retinoic acid, demonstrating that hormone can play a role in heterodimer stabilization...

..The results presented establish a connection between 20E exposure and changes in Ca2+ levels that are mediated by Ca2+ effector proteins, and thus establish a mechanistic framework for future studies...

..The data further indicate that PKC-mediated phosphorylation is also required for genes regulated indirectly by 20E-induced changes in the larval salivary gland...

..Our observations suggest that silencing by the unliganded EcR/USP receptor and the subsequent release of silencing by moderate steroid levels may play an important role in coordinating early phases of steroid driven development...

..Taken together, at least two factors may participate in the change in midgut trehalase activity: increase in trehalase activity and decrease in trehalase inhibitor activity, both of which may be induced by 20E...

..More generally, they suggest that cell identity factors like Fkh play a pivotal role in the normal control of developmental cell death...

..These studies indicate that ecdysone directs the death of larval tissues via the precise stage- and tissue-specific regulation of key death effector genes...

..Initially, moderate levels of ecdysteroid stimulate proliferation. Later, high levels of 20-hydroxyecdysone trigger a wave of apoptosis within the anlage that marks completion of its proliferative phase...

..This capacity to regulate distinct phases of development by different concentrations of a single hormone is probably achieved by differential sensitivity of target gene promoters to induction by the hormone-bound receptor(s)...

..These results redefine the ecdysone receptor as a dynamic complex whose activity may be altered by combinatorial interactions among subunits and ligand...

..Expression profiles of the genes after 20E stimulation indicated that four genes could be classified as early genes, while two are delayed early genes. The genes identified may provide insight into the PCD induced by a steroid hormone...

..We conclude that 20E slowly reduces food consumption and then indirectly induces a state of starvation resulting in the elevation of the mRNA levels of InR, IRS, PI3K110, and PDK in the Bombyx fat body during molting and pupation...

..Our results suggest that 20E and JH play major roles in the regulation of gene expression in response to immune challenge...

Purification of ecdysterone receptor from Drosophila melanogaster to apparent homogeneity is reported...

..b>Ecdysterone is an insect steroid hormone...

..20E acts via a heterodimer of two nuclear receptors, the ecdysone receptor (EcR) and Ultraspiracle, to directly regulate target gene transcription...

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..Thus, BR-C mRNAs are inducible by 20E only in the absence of JH, a finding that explains their metamorphosis-specific expression...

..The homology model complexes provide new insights that can be exploited in the rational design of new environmentally safe insecticides...

..The presence of juvenile hormone had no effect on accumulation of either transcript...

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..The midgut undergoes histolysis and remodeling during the larval to adult transition in holometabolous insects, but the molecular mechanisms underlying this process are not well understood...

..glue puff on the third chromosome does not regress when mutant salivary glands are cultured in the presence of ecdysterone; the three 68C glue protein mRNAs are not synthesized; and a transformed Drosophila strain carrying both a ..

..Furthermore, they suggest that the BR-C is placed at a different position within the 20E-controlled hierarchies than previously assumed, and that at least part of its pleiotropic functions are mediated by tissue-specific regulators...

..In vitro studies using transgenic Drosophila indicate that both repressor and activator factors regulate the timing of BhC4-1 expression in salivary glands...

..Our results reveal that the BR-C Z3 isoform is essential for BhC4-1-lacZ induction in prepupal salivary glands and constitute the first demonstration of the participation of early genes products on DNA puff genes regulation...

..Finally, by electrophoresis mobility shift assay we demonstrate that the HRE-IR forms specific complexes with nuclear extract proteins of normal pupae that increase after 20E stimulation...

..Interestingly to note, the entire cluster shows a peculiar genomic location, extending across two introns of the memory gene dunce, a large gene of Drosophila whose organization has proved to be remarkably complex...

..These results suggest that the increase of BmEcR mRNAs during the fifth instar is induced in vivo by a small increase in ecdysteroids...

The 2B5 region of the X-chromosome in Drosophila melanogaster plays a developmentally important role in the ecdysterone-triggered response of the late third instar salivary gland...

..shock protein (hsp) genes of Drosophila are expressed in cultured cells in response to the moulting hormone, ecdysterone. We show here that juvenile hormone (JHIII) and the juvenile hormone analogue, methoprene, inhibit that ..

..The orthologs of eukaryotic initiation factor 5C (eIF5C) are essential to the initiation of protein translation, and their regulation during development is not well known...

..The puff regresses near the end of the third instar as a result of an increased titer of the steroid hormone ecdysterone in the larval hemolymph...

A study of excretion in human urine of ecdysterone, which is the active component of several over-the-counter supplements such as "Ecdysten", reportedly used by athletes, is presented...

..g. secretion enhancer binding proteins, which act together in a synergistic manner with the 20E receptor and early gene products to establish a stage- and tissue-specific expression pattern...

..This hormone-induced disappearance is, in contrast to the 68C transcripts, not inhibited by cycloheximide...

..The correlation of a unique pattern of receptor isoform expression with a particular steroid-regulated fate suggests that variations in the pattern of receptor isoform expression may serve as important switches during development...

..Thus, ecdysteroid dienones show considerable potential as photoaffinity analogues for ecdysteroid binding proteins...

..The composite data suggest that PKC-mediated USP phosphorylation is required for 20E-induced gene expression in the salivary glands of Drosophila melanogaster...

..The relatively high biological activity of this dimeric compound is discussed...

..The results also demonstrate that the ecdysteroid receptor of D. melanogaster has a molecular mass higher than all other vertebrate steroid hormone receptors studied so far...

..These studies indicate that ecdysone triggers a two-step hierarchy composed of steroid-induced regulatory genes and apoptosis genes that, in turn, regulate the autophagic death of midgut cells during development...

..These data suggest that the EcR but not USP isoforms play distinct roles during the larval-pupal metamorphosis and EcRA plays a dominant role in transduction of ecdysteroid response in T. castaneum...

..The mutant ecd-1 appears to present interesting opportunities for the detailed study of the hormonal induction of a developmental process during the third larval instar.(ABSTRACT TRUNCATED AT 250 WORDS)..

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..These transcripts appeared to be expressed constitutively and expression levels were not affected by treatment of cells with 20-hydroxyecdysone. Arch...

..In addition, E75A, another ecdysone-induced transcription factor, and MHR3 itself suppressed MHR3 promoter activity by binding to the monomeric response element (MRE2). Therefore, MHR3 can be down-regulated both by itself and by E75A...

..Two transcription factors--BR-C and E75A--contribute to the cross-talk between the two hormones. It appears that BR-C is a key target of JH status quo action, and E75A is a part of the mechanism whereby JH prevents BR-C activation...

..Candidates for mediating the effect of BRC-Z3 on dendritic growth of MN1-MN5 include their synaptic inputs and non-neuronal CNS cells that interact with them through direct contact or diffusible factors...

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..All the ecdysteroids tested, viz. makisterone A, 20-hydroxyecdysone and the ecdysteroidal fraction from the silver fern Cheilanthes farinosa enhanced DNA synthesis...

..A model involving receptor partner deprivation is proposed that explains the synergistic interactions observed...

..Based on its expression patterns and unique structure, we propose that BMCPG1 may be a novel component of epicuticle of B. mori, and is probably involved in cross-linking of proteins via its GGY repeats...

..These results suggest that chromafenozide is a potent partial EcR agonist specific to lepidoptera; it appears to bind lepidopteran EcR with comparable affinity to ponasterone A, but may activate the EcR in a different manner...

..The combined results support the existence of a plasmalemmal ecdysteroid receptor, which may act in concert with the conventional EcR in various 20E-dependent developmental events...

..The 4-ethoxycarbonyl group on the benzene ring was indispensable for activity. The activity of compound 2 could be fully counteracted by methoprene, a JH agonist, but not by the dietary administration of 20-hydroxyecdysone...

..This effect could result from a JH II action on the 20E-induced genetic cascade through a modulation of EcR-B1, E75-B and HR3 expression...

..These observations demonstrate the importance of the ecdysone hormonal pathway, a new player in regulating longevity...

..The resultant QSAR models address the question of relative binding orientation of the two ligand families and can be useful as a virtual screen for new chemotypes...

..Some insects, however, show resistance to these analogs and this could be, inter alia, due to an ATP Binding Cassette Transporter like system that selectively pumps out the analogs...

..The loss of sensitivity to JH is the primary impetus to begin the process and 20E is the factor that drives the discs to enter the reversible state...

..Recent findings reveal that crosstalk between these pathways allows coordination of growth and developmental timing and thus determines final body size...

..The possible regulation of 20E levels by biosynthetic P450 enzymes and the roles of these early peaks in coordinating gene expression and late larval development are discussed...

..This is the first study implicating ecdysteroids in the developmental regulation of transferrin expression in an insect species...

..In addition, we show that HP19 inhibits the 20E-induced phosphorylation of the hexamerin receptor protein...

..Lastly, leg structures had a finite ability to respond to 20E; tarsal joints lost competence to respond after 32-34 h APF, while the remaining structures became incompetent after 44-46 h APF...

..This result is novel because it demonstrates for the first time that at least some 20E-mediated, mid-larval, developmental responses are controlled by an uncharacterized receptor that does not contain an RXR-like component...

..These results demonstrate an interaction between steroid hormone signaling and the heterochronic pathway in insects...

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..These data show that the proliferation of ISCs is under both developmental and endocrine regulation...

..These data suggest that the expression of Tcbr during the final instar larval stage promotes pupal program while suppressing the larval and adult programs ensuring a transitory pupal stage in holometabolous insects...

..Here we show a novel functional role for the aspartic proteinase cathepsin D during insect metamorphosis...

..In order to identify these processes, we generated mutants in the IP3 receptor gene (itpr) of Drosophila and studied their phenotype during development...

..We propose that DHR78 is a ligand-activated receptor that plays a central role in directing the onset of Drosophila metamorphosis...

..The effects of directed modification and mutagenesis offer a strategy for developing hypotheses and considerations for studying in vivo function...

..These studies demonstrate that larval organ culture can be used to identify Drosophila genes that are regulated by hormones other than 20E, and provide a basis for studying crosstalk between multiple hormone signaling pathways...

..All together, our results suggest that the Ha-lectin gene is involved in innate immunity, and may also participate in the molting process...

..Recent findings suggest that other hormones and receptors might also be involved...

..Furthermore, our results add to the recent findings which indicate the need for caution in interpreting the activities of GST fusion proteins...

..Recent studies suggest that the E93 gene is both necessary and sufficient to target tissues for ecdysone-induced apoptosis...

..The features of these specimens indicate that BgEcR-A is required for adult-specific developmental processes, such as wing development, prothoracic gland degeneration and normal choriogenesis...

..The transformed dimeric analogue of 20-hydroxyecdysone retained the high agonistic activity on the ecdysone receptor in the B(II)-bioassay compared with the original 20E...

..Our results, though, do not exclude reasons of metabolic stability of the compounds in C. tentans, which we have not investigated in this report...

..Topical application of a juvenile hormone analog, fenoxycarb, just after the 20E injection, suppressed this induction. BmChiR1 expression is therefore upregulated by ecdysteroid and downregulated by juvenile hormone...

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..In summary, our study indicates that Smt3 is required for the ecdysteroid synthesis pathway at the time of puparium formation...

..This study demonstrates ecdysone's role in modifying nerve terminal development and neuromuscular junction function...

DESCRIPTION (provided by the applicant): Ecdysterone and juvenile hormone (JH) are the primary endocrine regulators of reproduction and development in insects...

..3) to purify and characterize another factor likely to be involved in the developmental regulation of the Drosophila hsp23 gene (ecdysterone receptor), and (4) to characterize a second type of developmental regulation of the hsp23 gene.

..Thus it offers a unique opportunity to elucidate how the activity of the clock is coupled to the mechanism that controls a behavioral output. ..

..In addition, this study will provide insight into the molecular mechanisms by which systemic hormonal signals are refined into stage- and tissue-specific biological responses during development. ..

..The work will include identification of exon-intron organization and recovery of upstream flanking DNA, which will be analyzed for potential regulatory elements. ..

..Overall, the purpose of this study is to examine 4-nonylphenol's effects on breast cancer growth and its mechanism of action on the mammary tumor. ..

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..This research will provide new insights into how higher organisms, including humans, cope with toxic compounds in their environment and establish Drosophila as a new model system for characterizing xenobiotic response regulation. ..

..These studies provide cloned genes, molecular approaches, and characterization of regulatory processes that can potentially be manipulated to interfere with disease transmission by blood-feeding arthropods. ..

..Finally, our studies provide a foundation for determining how steroids control cell death in humans, with implications for understanding and treating human disease. ..

..does TEC-recipient inosculation play in TEC vascularization? (b) What are the biological functions of CD144, principally with regards to its role in inosculation and its regulation by the unique TEC microenvironment? ..

..These studies will contribute to an increased understanding of the genetics and physiology of the mosquito, a disease vector with considerable impact on human health and productivity...

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