Investigations into the role of transcription repressor factors in the regulation of Krüppel and the role of Krüppel in anterior segmentation in Drosophila melanogaster

Abstract

Differential transcription is mainly responsible for the process of cellular differentiation, and the Drosophila segmentation cascade constitutes a model system in transcriptional studies. In recent years, our laboratory has been investigating the hypothesis that a combined activity of transcription repressive factors, in addition to delimiting the expression contours of target genes, probably prevents widespread expression of these genes. The premise is that if it were not for the action of local repressors, gene expression could occur in wider areas than detected under physiological conditions, given the expression of activators throughout the entire embryo. This situation is compatible with the syncytial environment of the Drosophila embryo and is implicit in the regulation of the segmentation cascade gene Krüppel (Kr), expressed in a central domain of the embryo. According to the literature, Kr is subject to the action of activators that cover the entire embryo, and the action of regional repressors. Here we propose the simultaneous removal of all transcription factors identified as repressors of Kr in the anterior region of the embryo, with the expectation of detecting a broad expansion of anterior Kr expression. On the other hand, if Kr expression is fundamental for the generation of the thorax and abdomen, ectopic Kr expression experiments will test the hypothesis that its containment is necessary to not compromise the expression of genes responsible for the specification of the anterior region of the body. The results of these experiments will constitute an initial step for future experiments that investigate molecular mechanisms involving the action between transcription activating and repressing factors when interacting with regulatory regions of DNA, a subject that is still poorly understood in transcriptional studies.