BACKGROUND: Epigenetic modifications including DNA methylation and post-translational modifications of histones are known to regulate gene expression. Antagonistic activities of histone acetyltransferases (HATs) and histone deacetylases (HDACs) mediate transcriptional reprogramming during insect development as shown in Drosophila melanogaster and other insects. Juvenile hormones (JH) play vital roles in the regulation of growth, development, metamorphosis, reproduction and other physiological processes. However, our current understanding of epigenetic regulation of JH action is still limited. Hence, we studied the role of CREB binding protein (CBP, contains HAT domain) and Trichostatin A (TSA, HDAC inhibitor) on JH action. RESULTS: Exposure of Tribolium castaneum cells (TcA cells) to JH or TSA caused an increase in expression of Kr-h1 (a known JH-response gene) and 31 or 698 other genes respectively. Knockdown of the gene coding for CBP caused a decrease in the expression of 456 genes including Kr-h1. Interestingly, the expression of several genes coding for transcription factors, nuclear receptors, P450 and fatty acid synthase family members that are known to mediate JH action were affected by CBP knockdown or TSA treatment. CONCLUSIONS: These data suggest that acetylation and deacetylation mediated by HATs and HDACs play an important role in JH action.

• Klíčová slova
• FOXO Tribolium and TcA cells, HAT, HDAC, Kr-h1,
• MeSH
• acetylace MeSH
• dvouvláknová RNA metabolismus   MeSH
• epigeneze genetická účinky léků   MeSH
• hmyzí proteiny antagonisté a inhibitory   genetika   metabolismus   MeSH
• kyseliny hydroxamové farmakologie   MeSH
• protein vázající CREB antagonisté a inhibitory   genetika   metabolismus   MeSH
• RNA interference MeSH
• Tribolium účinky léků   růst a vývoj   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• dvouvláknová RNA MeSH
• hmyzí proteiny MeSH
• kyseliny hydroxamové MeSH
• protein vázající CREB MeSH
• trichostatin A MeSH Prohlížeč

BACKGROUND: Juvenile hormones (JH) and ecdysteroids control postembryonic development in insects. They serve as valuable targets for pest management. Hence, understanding the molecular mechanisms of their action is of crucial importance. CREB-binding protein (CBP) is a universal transcriptional co-regulator. It controls the expression of several genes including those from hormone signaling pathways through co-activation of many transcription factors. However, the role of CBP during postembryonic development in insects is not well understood. Therefore, we have studied the role of CBP in postembryonic development in Tribolium, a model coleopteran insect. RESULTS: CBP is ubiquitously expressed in the red flour beetle, Tribolium castaneum. RNA interference (RNAi) mediated knockdown of CBP resulted in a decrease in JH induction of Kr-h1 gene expression in Tribolium larvae and led to a block in their development. Moreover, the injection of CBP double-stranded RNA (dsRNA) showed lethal phenotypes within 8 days of injection. RNA-seq and subsequent differential gene expression analysis identified CBP target genes in Tribolium. Knockdown of CBP caused a decrease in the expression of 1306 genes coding for transcription factors and other proteins associated with growth and development. Depletion of CBP impaired the expression of several JH response genes (e.g., Kr-h1, Hairy, early trypsin) and ecdysone response genes (EcR, E74, E75, and broad complex). Further, GO enrichment analyses of the downregulated genes showed enrichment in different functions including developmental processes, pigmentation, anatomical structure development, regulation of biological and cellular processes, etc. CONCLUSION: These data suggest diverse but crucial roles for CBP during postembryonic development in the coleopteran model insect, Tribolium. It can serve as a target for RNAi mediated pest management of this stored product pest.

• Klíčová slova
• CBP, Ecdysone, Juvenile hormone, Kr-h1, RNA seq, RNAi, Tribolium,
• MeSH
• exprese genu MeSH
• hmyzí proteiny antagonisté a inhibitory   genetika   metabolismus   fyziologie   MeSH
• juvenilní hormony farmakologie   MeSH
• larva genetika   metabolismus   MeSH
• protein vázající CREB antagonisté a inhibitory   genetika   metabolismus   fyziologie   MeSH
• RNA interference MeSH
• Tribolium genetika   růst a vývoj   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Research Support, N.I.H., Extramural MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH
• Názvy látek
• hmyzí proteiny MeSH
• juvenilní hormony MeSH
• protein vázající CREB MeSH

Insect larvae metamorphose to winged and reproductive adults either directly (hemimetaboly) or through an intermediary pupal stage (holometaboly). In either case juvenile hormone (JH) prevents metamorphosis until a larva has attained an appropriate phase of development. In holometabolous insects, JH acts through its putative receptor Methoprene-tolerant (Met) to regulate Krüppel-homolog 1 (Kr-h1) and Broad-Complex (BR-C) genes. While Met and Kr-h1 prevent precocious metamorphosis in pre-final larval instars, BR-C specifies the pupal stage. How JH signaling operates in hemimetabolous insects is poorly understood. Here, we compare the function of Met, Kr-h1 and BR-C genes in the two types of insects. Using systemic RNAi in the hemimetabolous true bug, Pyrrhocoris apterus, we show that Met conveys the JH signal to prevent premature metamorphosis by maintaining high expression of Kr-h1. Knockdown of either Met or Kr-h1 (but not of BR-C) in penultimate-instar Pyrrhocoris larvae causes precocious development of adult color pattern, wings and genitalia. A natural fall of Kr-h1 expression in the last larval instar normally permits adult development, and treatment with an exogenous JH mimic methoprene at this time requires both Met and Kr-h1 to block the adult program and induce an extra larval instar. Met and Kr-h1 therefore serve as JH-dependent repressors of deleterious precocious metamorphic changes in both hemimetabolous and holometabolous juveniles, whereas BR-C has been recruited for a new role in specifying the holometabolous pupa. These results show that despite considerable evolutionary distance, insects with diverse developmental strategies employ a common-core JH signaling pathway to commit to adult morphogenesis.

• MeSH
• biologické modely MeSH
• hmyz účinky léků   genetika   růst a vývoj   MeSH
• hmyzí geny genetika   MeSH
• juvenilní hormony farmakologie   MeSH
• konzervovaná sekvence genetika   MeSH
• larva účinky léků   genetika   MeSH
• represorové proteiny genetika   metabolismus   MeSH
• signální transdukce účinky léků   genetika   MeSH
• stadia vývoje účinky léků   genetika   MeSH
• stárnutí účinky léků   genetika   MeSH
• vývojová regulace genové exprese účinky léků   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• juvenilní hormony MeSH
• represorové proteiny MeSH

Juvenile hormone (JH) postpones metamorphosis of insect larvae until they have attained an appropriate stage and size. Then, during the final larval instar, a drop in JH secretion permits a metamorphic molt that transforms larvae to adults either directly (hemimetaboly) or via a pupal stage (holometaboly). In both scenarios, JH precludes metamorphosis by activating the Kr-h1 gene through a JH receptor, Methoprene-tolerant (Met). Removal of Met, Kr-h1, or JH itself triggers deleterious precocious metamorphosis. Although JH is thought to maintain the juvenile status throughout larval life, various methods of depleting JH failed to induce metamorphosis in early-instar larvae. To determine when does JH signaling become important for the prevention of precocious metamorphosis, we chose the hemimetabolous bug, Pyrrhocoris apterus, and the holometabolous silkworm, Bombyx mori. Both species undergo a fixed number of five larval instars. Pyrrhocoris larvae subjected to RNAi-mediated knockdown of Met or Kr-h1 underwent precocious adult development when treated during the fourth (penultimate) instar, but younger larvae proved increasingly resistant to loss of either gene. The earliest instar developing minor signs of precocious metamorphosis was the third. Therefore, the JH-response genes may not be required to maintain the larval program during the first two larval instars. Next, we examined Bombyx mod mutants that cannot synthesize authentic, epoxidized forms of JH. Although mod larvae expressed Kr-h1 mRNA at severely reduced levels since hatching, they only entered metamorphosis by pupating after four, rarely three instars. Based on findings in Pyrrhocoris and Bombyx, we propose that insect postembryonic development is initially independent of JH. Only later, when larvae gain competence to enter metamorphosis, JH signaling becomes necessary to prevent precocious metamorphosis and to optimize growth.

• Klíčová slova
• Heterochronic development, Hormonal signaling, Insect metamorphosis, Juvenile hormone, Krüppel homolog 1, Methoprene-tolerant,
• MeSH
• analýza rozptylu MeSH
• biologická proměna fyziologie   MeSH
• bourec růst a vývoj   MeSH
• DNA primery genetika   MeSH
• druhová specificita MeSH
• Heteroptera růst a vývoj   MeSH
• juvenilní hormony metabolismus   MeSH
• larva fyziologie   MeSH
• methopren MeSH
• RNA interference MeSH
• signální transdukce fyziologie   MeSH
• transkripční faktory Krüppel-like metabolismus   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• DNA primery MeSH
• juvenilní hormony MeSH
• methopren MeSH
• transkripční faktory Krüppel-like MeSH

Juvenile hormone (JH), a sesquiterpenoid produced by the insect corpus allatum gland (CA), prevents metamorphosis in larvae and stimulates vitellogenesis in adult females. Whether the same JH signaling pathway regulates both processes is presently unknown. Here, we employ the robust JH response during reproduction and development of the linden bug, Pyrrhocoris apterus, to compare the function of key JH-signaling genes encoding the JH receptor, Methoprene-tolerant (Met), its binding partner Taiman (Tai), and a JH-inducible protein, Krüppel-homolog 1 (Kr-h1). RNA interference (RNAi) with Met or Tai, but not Kr-h1, blocked ovarian development and suppressed vitellogenin gene expression in the fat body of females raised under reproduction-inducing conditions. Loss of Met and Tai matched the effects of CA ablation or the natural absence of JH during reproductive diapause. Stimulation of vitellogenesis by treatment of diapausing females with a JH mimic methoprene also required both Met and Tai in the fat body, whereas Kr-h1 RNAi had no effect. Therefore, the Met-Tai complex likely functions as a JH receptor during vitellogenesis. In contrast to Met and Kr-h1 that are both required for JH to prevent precocious metamorphosis in P. apterus larvae, removal of Tai disrupted larval ecdysis without causing premature adult development. Our results show that while Met operates during metamorphosis in larvae and reproduction in adult females, its partner Tai is only required for the latter. The diverse functions of JH thus likely rely on a common receptor whose actions are modulated by distinct components.

• Klíčová slova
• Diapause, Metamorphosis, Methoprene-tolerant, Oogenesis, Vitellogenesis, bHLH-PAS,
• MeSH
• diapauza hmyzu MeSH
• Heteroptera růst a vývoj   metabolismus   fyziologie   MeSH
• juvenilní hormony metabolismus   MeSH
• larva růst a vývoj   metabolismus   fyziologie   MeSH
• rozmnožování MeSH
• sexuální chování zvířat MeSH
• shazování tělního pokryvu MeSH
• signální transdukce MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• juvenilní hormony MeSH

Despite important roles played by juvenile hormone (JH) in insects, the mechanisms underlying its action were until recently unknown. A breakthrough has been the demonstration that the bHLH-PAS protein Met is an intracellular receptor for JH. Binding of JH to Met triggers dimerization of Met with its partner protein Tai, and the resulting complex induces transcription of target genes. In addition, JH can potentiate this response by phosphorylating Met and Tai via cell membrane, second-messenger signaling. An important gene induced by the JH-Met-Tai complex is Kr-h1, which inhibits metamorphosis. Kr-h1 represses an 'adult specifier' gene E93. The action of this JH-activated pathway in maintaining the juvenile status is dispensable during early postembryonic development when larvae/nymphs lack competence to metamorphose.

• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

Understanding the social evolution leading to insect eusociality requires, among other, a detailed insight into endocrine regulatory mechanisms that have been co-opted from solitary ancestors to play new roles in the complex life histories of eusocial species. Bumblebees represent well-suited models of a relatively primitive social organization standing on the mid-way to highly advanced eusociality and their queens undergo both, a solitary and a social phase, separated by winter diapause. In the present paper, we characterize the gene expression levels of major endocrine regulatory pathways across tissues, sexes, and life-stages of the buff-tailed bumblebee, Bombus terrestris, with special emphasis on critical stages of the queen's transition from solitary to social life. We focused on fundamental genes of three pathways: (1) Forkhead box protein O and insulin/insulin-like signaling, (2) Juvenile hormone (JH) signaling, and (3) Adipokinetic hormone signaling. Virgin queens were distinguished by higher expression of forkhead box protein O and downregulated insulin-like peptides and JH signaling, indicated by low expression of methyl farnesoate epoxidase (MFE) and transcription factor Krüppel homolog 1 (Kr-h1). Diapausing queens showed the expected downregulation of JH signaling in terms of low MFE and vitellogenin (Vg) expressions, but an unexpectedly high expression of Kr-h1. By contrast, reproducing queens revealed an upregulation of MFE and Vg together with insulin signaling. Surprisingly, the insulin growth factor 1 (IGF-1) turned out to be a queen-specific hormone. Workers exhibited an expression pattern of MFE and Vg similar to that of reproducing queens. Males were characterized by high Kr-h1 expression and low Vg level. The tissue comparison unveiled an unexpected resemblance between the fat body and hypopharyngeal glands across all investigated genes, sexes, and life stages.

• Klíčová slova
• caste differentiation, diapause, endocrine glands, hormones, reproduction, social evolution, social insects,
• Publikační typ
• časopisecké články MeSH

Juvenile hormones (JH) and ecdysteroids regulate many biological and metabolic processes. CREB-binding protein (CBP) is a transcriptional co-regulator with histone acetyltransferase (HAT) activity. Therefore, CBP is involved in activation of many transcription factors that regulate expression of genes associated with postembryonic development in insects. However, the function of CBP in JH action in insects is not well understood. Hence, we studied the role of CBP in JH action in the red flour beetle, Tribolium castaneum and the Tribolium cell line. CBP knockdown caused a decrease in JH induction of genes, Kr-h1, 4EBP and G13402 in T. castaneum larvae, adults and TcA cells whereas, Trichostatin A [TSA, a histone deacetylase (HDAC) inhibitor] induced the expression of these JH-response genes. Western blot analysis with specific antibodies revealed the requirement of CBP for the acetylation of H3K18 and H3K27 in both T. castaneum and TcA cells. Chromatin immunoprecipitation (Chip) assays showed the importance of CBP-mediated acetylation of H3K27 for JH induction of Kr-h1, 4EBP, and G13402 in TcA cells. These data suggest that CBP plays an important role in JH action in the model insect, T.castaneum.

• MeSH
• acetylace MeSH
• genový knockout MeSH
• histony metabolismus   MeSH
• hmyzí proteiny genetika   metabolismus   MeSH
• juvenilní hormony farmakologie   MeSH
• protein vázající CREB genetika   metabolismus   MeSH
• Tribolium genetika   růst a vývoj   metabolismus   MeSH
• vývojová regulace genové exprese účinky léků   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Research Support, N.I.H., Extramural MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH
• Názvy látek
• histony MeSH
• hmyzí proteiny MeSH
• juvenilní hormony MeSH
• protein vázající CREB MeSH