%0 Journal Article
%T Cloning and characterization of cDNAs encoding putative CTCFs in the mosquitoes, Aedes aegypti and Anopheles gambiae
%A Christine E Gray
%A Craig J Coates
%J BMC Molecular Biology
%D 2005
%I BioMed Central
%R 10.1186/1471-2199-6-16
%X We have identified and characterized putative CTCF homologs in the medically-important mosquitoes, Aedes aegypti and Anopheles gambiae. These genes encode polypeptides with eleven C2H2 zinc fingers that show significant similarity to those of vertebrate CTCFs, despite at least 500 million years of divergence. The mosquito CTCFs are constitutively expressed and are upregulated in early embryos and in the ovaries of blood-fed females. We have uncovered significant bioinformatics evidence that CTCF is widespread, at least among Drosophila species. Finally, we show that the An. gambiae CTCF binds two known insulator sequences.Mosquito CTCFs are likely orthologous to the widely-characterized vertebrate CTCFs and potentially also serve an insulating function. As such, CTCF may provide a powerful tool for improving transgene expression in these mosquitoes through the identification of endogenous binding sites.CTCF (CCCTC-binding factor) was originally identified as a transcriptional repressor in studies of the chicken lysozyme silencer [1] and the regulation of the chicken c-myc gene [2]. Since that time, CTCF has been extensively characterized in vertebrates as a ubiquitously-expressed, highly-conserved, multivalent transcription factor that utilizes different zinc finger (ZF) combinations to specifically bind diverse nucleotide sequences, resulting in the repression or activation of target genes, creation of hormone-responsive silencers and the formation of enhancer-blocking boundary elements (reviewed in [3]). Multiple, independent studies have established vertebrate CTCF as a central player in the regulation of gene expression via its association with every known vertebrate insulator [3-5]. Further characterization of these proteins revealed their insulator function to be central in three contexts: (a) constitutive insulation of the chicken ¦Â-globin gene at the 5'HS4 site [6,7] and the human apolipoprotein B gene at the 5' boundary [8], (b) imprinted insulation via met
%U http://www.biomedcentral.com/1471-2199/6/16