Chorion gene activation and repression is dependent on BmC/EBP expression and binding to cognate cis-elements.
From the different cis-elements clustered on silkmoth chorion gene promoters, C/EBP binding sites predominate. Their sequence composition and dispersal vary amongst promoters of diverse developmental specificity. Occupancy of these sites by BmC/EBP was examined through Southwestern and ChIP assays modified to suit ovarian follicular cells. For the genes studied, binding of BmC/EBP coincided with the respective stages of transcriptional activation. However, the factor was reloaded on promoter sequences long after individual gene repression. Furthermore, suppression of BmC/EBP transcription in developing follicles resulted in de-regulation of chorion gene expression. A biphasic function of BmC/EBP, according to which it may act as both an activator and a repressor during silkmoth choriogenesis, is considered under the light of the presented data.
Papantonis
Argyris
A
Department of Biochemistry and Molecular Biology, Faculty of Biology, National and Kapodistrian University of Athens, Panepistimiopolis, Kouponia, 15701 Athens, Attiki, Greece.
Sourmeli
Sissy
S
Lecanidou
Rena
R
D000818:Animals; D001483:Base Sequence; D026501:Blotting, Southwestern; D012831:Bombyx / Q000235:genetics / Q000254:growth & development*; D022762:CCAAT-Enhancer-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D002823:Chorion / Q000254:growth & development* / Q000378:metabolism; D047369:Chromatin Immunoprecipitation; D005260:Female; D018507:Gene Expression Regulation, Developmental; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D015533:Transcriptional Activation; D014818:Vitellogenesis / Q000235:genetics
D022762:CCAAT-Enhancer-Binding Proteins; D019476:Insect Proteins