Evolution of insect metamorphosis: Functional analysis of the metamorphic toolkit formed by E93, Krüppel homolog 1, and Broad-Complex transcription factors

2016 ◽  
Author(s):  
Enric Ureña
Keyword(s):  
Functional Analysis ◽  
Transcription Factors ◽  
Insect Metamorphosis ◽  
Krüppel Homolog 1 ◽  
Broad Complex

scholarly journals The evolution of insect metamorphosis: a developmental and endocrine view

2019 ◽  
Vol 374 (1783) ◽  
pp. 20190070 ◽  
Author(s):  
James W. Truman ◽  
Lynn M. Riddiford
Keyword(s):  
Transcription Factors ◽  
Experimental Treatment ◽  
The Other ◽  
Life Stages ◽  
Developmental Genetic ◽  
Theme Issue ◽  
Insect Metamorphosis ◽  
Krüppel Homolog 1 ◽  
Complete Metamorphosis ◽  
Insight Into

Developmental, genetic and endocrine data from diverse taxa provide insight into the evolution of insect metamorphosis. We equate the larva–pupa–adult of the Holometabola to the pronymph–nymph–adult of hemimetabolous insects. The hemimetabolous pronymph is a cryptic embryonic stage with unique endocrinology and behavioural modifications that probably served as preadaptations for the larva. It develops in the absence of juvenile hormone (JH) as embryonic primordia undergo patterning and morphogenesis, the processes that were arrested for the evolution of the larva. Embryonic JH then drives tissue differentiation and nymph formation. Experimental treatment of pronymphs with JH terminates patterning and induces differentiation, mimicking the processes that occurred during the evolution of the larva. Unpatterned portions of primordia persist in the larva, becoming imaginal discs that form pupal and adult structures. Key transcription factors are associated with the holometabolous life stages: Krüppel-homolog 1 ( Kr-h1 ) in the larva, broad in the pupa and E93 in the adult. Kr-h1 mediates JH action and is found whenever JH acts, while the other two genes direct the formation of their corresponding stages. In hemimetabolous forms, the pronymph has low Broad expression, followed by Broad expression through the nymphal moults, then a switch to E93 to form the adult. This article is part of the theme issue ‘The evolution of complete metamorphosis’.

scholarly journals The ecdysone-inducible Broad-complex and E74 early genes interact to regulate target gene transcription and Drosophila metamorphosis.

Genetics ◽  
1995 ◽  
Vol 141 (3) ◽  
pp. 1025-1035 ◽  
Author(s):  
J C Fletcher ◽  
C S Thummel
Keyword(s):  
Transcription Factors ◽  
Gene Transcription ◽  
Synergistic Effects ◽  
Group Analysis ◽  
Complementation Group ◽  
Primary Response ◽  
Early Gene ◽  
Secondary Response ◽  
Insect Metamorphosis ◽  
Broad Complex

Abstract Pulses of the steroid hormone ecdysone initiate Drosophila metamorphosis by inducing widespread changes in gene expression. The Broad-Complex (BR-C) and E74 are induced directly by ecdysone and encode families of transcription factors that regulate ecdysone primary- and secondary-response genes. Genetic analyses have revealed that mutations in the BR-C and E74 are lethal during metamorphosis and that these mutations cause some similar lethal phenotypes and alterations in secondary-response gene transcription. To examine whether the BR-C and E74 function together during development, we have combined representative alleles from each BR-C and E74 complementation group. Analysis of the morphological and molecular phenotypes of the double-mutant animals reveals that BR-C and E74 alleles act together to produce both novel and synergistic effects. We find that the BR-C and E74 share functions in puparium formation, pupation and early gene induction. In addition, our evidence suggests that the BR-C and E74 transcription factors may directly interact to regulate the expression of salivary gland glue and late genes. This data is consistent with current models which propose that combinations of ecdysone primary-response genes regulate common morphogenetic pathways during insect metamorphosis.

scholarly journals Krüppel Homolog 1 Inhibits Insect Metamorphosis via Direct Transcriptional Repression of Broad-Complex, a Pupal Specifier Gene

2015 ◽  
Vol 291 (4) ◽  
pp. 1751-1762 ◽  
Author(s):  
Takumi Kayukawa ◽  
Keisuke Nagamine ◽  
Yuka Ito ◽  
Yoshinori Nishita ◽  
Yukio Ishikawa ◽  
...  
Keyword(s):  
Transcriptional Repression ◽  
Functional Relationship ◽  
Upstream Sequence ◽  
Molting Hormone ◽  
Mobility Shift ◽  
Considerable Portion ◽  
Insect Metamorphosis ◽  
Krüppel Homolog 1 ◽  
Broad Complex ◽  
Inducible Gene

The Broad-Complex gene (BR-C) encodes transcription factors that dictate larval-pupal metamorphosis in insects. The expression of BR-C is induced by molting hormone (20-hydroxyecdysone (20E)), and this induction is repressed by juvenile hormone (JH), which exists during the premature larval stage. Krüppel homolog 1 gene (Kr-h1) has been known as a JH-early inducible gene responsible for repression of metamorphosis; however, the functional relationship between Kr-h1 and repression of BR-C has remained unclear. To elucidate this relationship, we analyzed cis- and trans elements involved in the repression of BR-C using a Bombyx mori cell line. In the cells, as observed in larvae, JH induced the expression of Kr-h1 and concurrently suppressed 20E-induced expression of BR-C. Forced expression of Kr-h1 repressed the 20E-dependent activation of the BR-C promoter in the absence of JH, and Kr-h1 RNAi inhibited the JH-mediated repression, suggesting that Kr-h1 controlled the repression of BR-C. A survey of the upstream sequence of BR-C gene revealed a Kr-h1 binding site (KBS) in the BR-C promoter. When KBS was deleted from the promoter, the repression of BR-C was abolished. Electrophoresis mobility shift demonstrated that two Kr-h1 molecules bound to KBS in the BR-C promoter. Based on these results, we conclude that Kr-h1 protein molecules directly bind to the KBS sequence in the BR-C promoter and thereby repress 20E-dependent activation of the pupal specifier, BR-C. This study has revealed a considerable portion of the picture of JH signaling pathways from the reception of JH to the repression of metamorphosis.

Temporal regulation of Drosophila salivary gland degeneration by the Broad-Complex transcription factors

2002 ◽  
Vol 140 (1-3) ◽  
pp. 67-78 ◽  
Author(s):  
Silvia Kuchárová-Mahmood ◽  
Ivan Raška ◽  
Bernard M. Mechler ◽  
Robert Farkaš
Keyword(s):  
Transcription Factors ◽  
Salivary Gland ◽  
Temporal Regulation ◽  
Broad Complex

scholarly journals Genome-Wide Identification of Zn2Cys6 Class Fungal-Specific Transcription Factors (ZnFTFs) and Functional Analysis of UvZnFTF1 in Ustilaginoidea virens

Rice Science ◽  
2021 ◽  
Vol 28 (6) ◽  
pp. 567-578
Author(s):  
Song Tianqiao ◽  
Zhang Xiong ◽  
Zhang You ◽  
Liang Dong ◽  
Yan Jiaoling ◽  
...  
Keyword(s):  
Functional Analysis ◽  
Transcription Factors ◽  
Ustilaginoidea Virens ◽  
Genome Wide

scholarly journals Characterization of E93 in neometabolous thrips Frankliniella occidentalis and Haplothrips brevitubus

PLoS ONE ◽  
2021 ◽  
Vol 16 (7) ◽  
pp. e0254963
Author(s):  
Youhei Suzuki ◽  
Takahiro Shiotsuki ◽  
Akiya Jouraku ◽  
Ken Miura ◽  
Chieka Minakuchi
Keyword(s):  
Larval Stage ◽  
Hormonal Regulation ◽  
Frankliniella Occidentalis ◽  
Expression Profiles ◽  
Mrna Levels ◽  
Transcript Levels ◽  
Adult Transition ◽  
Thrips Species ◽  
Insect Metamorphosis ◽  
Krüppel Homolog 1

Insect metamorphosis into an adult occurs after the juvenile hormone (JH) titer decreases at the end of the juvenile stage. This generally coincides with decreased transcript levels of JH-response transcription factors Krüppel homolog 1 (Kr-h1) and broad (br), and increased transcript levels of the adult specifier E93. Thrips (Thysanoptera) develop through inactive and non-feeding stages referred to as “propupa” and “pupa”, and this type of distinctive metamorphosis is called neometaboly. To understand the mechanisms of hormonal regulation in thrips metamorphosis, we previously analyzed the transcript levels of Kr-h1 and br in two thrips species, Frankliniella occidentalis (Thripidae) and Haplothrips brevitubus (Phlaeothripidae). In both species, the transcript levels of Kr-h1 and br decreased in the “propupal” and “pupal” stages, and their transcription was upregulated by exogenous JH mimic treatment. Here we analyzed the developmental profiles of E93 in these two thrips species. Quantitative RT-PCR revealed that E93 expression started to increase at the end of the larval stage in F. occidentalis and in the “propupal” stage of H. brevitubus, as Kr-h1 and br mRNA levels decreased. Treatment with an exogenous JH mimic at the onset of metamorphosis prevented pupal-adult transition and caused repression of E93. These results indicated that E93 is involved in adult differentiation after JH titer decreases at the end of the larval stage of thrips. By comparing the expression profiles of Kr-h1, br, and E93 among insect species, we propose that the “propupal” and “pupal” stages of thrips have some similarities with the holometabolous prepupal and pupal stages, respectively.

scholarly journals Ecdysone-induced expression of the caspase DRONC during hormone-dependent programmed cell death in Drosophila is regulated by Broad-Complex

2002 ◽  
Vol 157 (6) ◽  
pp. 985-996 ◽  
Author(s):  
Dimitrios Cakouros ◽  
Tasman Daish ◽  
Damali Martin ◽  
Eric H. Baehrecke ◽  
Sharad Kumar
Keyword(s):  
Gene Expression ◽  
Cell Death ◽  
Steroid Hormone ◽  
Drosophila Cell ◽  
Interaction Sites ◽  
Number Of Genes ◽  
Insect Metamorphosis ◽  
Caspase Regulation ◽  
Broad Complex ◽  
Drosophila Cell Line

The steroid hormone ecdysone regulates both cell differentiation and cell death during insect metamorphosis, by hierarchical transcriptional regulation of a number of genes, including the Broad-Complex (BR-C), the zinc finger family of transcription factors. These genes in turn regulate the transcription of a number of downstream genes. DRONC, a key apical caspase in Drosophila, is the only known caspase that is transcriptionally regulated by ecdysone during development. We demonstrate that dronc gene expression is ablated or reduced in BR-C mutant flies. Using RNA interference in an ecdysone-responsive Drosophila cell line, we show that DRONC is essential for ecdysone-mediated cell death, and that dronc upregulation in these cells is controlled by BR-C. Finally, we show that the dronc promoter has BR-C interaction sites, and that it can be transactivated by a specific isoform of BR-C. These results indicate that BR-C plays a key role in ecdysone-mediated caspase regulation.

scholarly journals A Phenome-Based Functional Analysis of Transcription Factors in the Cereal Head Blight Fungus, Fusarium graminearum

2011 ◽  
Vol 7 (10) ◽  
pp. e1002310 ◽  
Author(s):  
Hokyoung Son ◽  
Young-Su Seo ◽  
Kyunghun Min ◽  
Ae Ran Park ◽  
Jungkwan Lee ◽  
...  
Keyword(s):  
Functional Analysis ◽  
Transcription Factors ◽  
Fusarium Graminearum ◽  
Head Blight
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