Graded Dorsal and Differential Gene Regulation in the Drosophila Embryo

Abstract

A gradient of Dorsal activity patterns the dorsoventral (DV) axis of the early Drosophila melanogaster embryo by controlling the expression of genes that delineate presumptive mesoderm, neuroectoderm, and dorsal ectoderm. The availability of the Drosophila melanogaster genome sequence has accelerated the study of embryonic DV patterning, enabling the use of systems-level approaches. As a result, our understanding of Dorsal-dependent gene regulation has expanded to encompass a collection of more than 50 genes and 30 cis-regulatory sequences. This information, which has been integrated into a spatiotemporal atlas of gene regulatory interactions, comprises one of the best-understood networks controlling any developmental process to date. In this article, we focus on how Dorsal controls differential gene expression and how recent studies have expanded our understanding of Drosophila embryonic development from the cis-regulatory level to that controlling morphogenesis of the embryo.

Genome wide identification ofTriboliumdorsoventral patterning genes

“…Further, Tc-snail seems to be regulated by Tc-Toll and Tc-twi (Fig. 6C), like in Drosophila (Reeves and Stathopoulos, 2009). The same applies for the homologues of the Drosophila twi target genes heartless (htl) and down of FGF receptor (dof ) (Beermann and Schröder, 2008;Beiman et al, 1996;Gisselbrecht et al, 1996;Imam et al, 1999;Vincent et al, 1998) (Fig.…”

“…In both Drosophila and Tribolium, Toll signalling leads to the formation of a ventral-to-dorsal nuclear gradient of the NF-κB transcription factor Dorsal. The NF-κB/Dorsal gradient is fairly stable in Drosophila and patterns the DV axis by activating or repressing target genes in a concentration-dependent manner (Hong et al, 2008;Ozdemir et al, 2014;Reeves and Stathopoulos, 2009;Reeves et al, 2012;Roth et al, 1989;Rushlow et al, 1989;Steward, 1989). Among the targets of NF-κB/Dorsal are transcription factors directly involved in cell fate specification such as twist (twi), as well as components of other signalling pathways which indirectly specify subregions along the DV axis.…”

Epithelial-mesenchymal transitions: insights from development

“…Upon activation and binding of Spätzle to the Toll receptor, Dorsal (an ortholog of NFb) is activated and transported to the nucleus (Roth, 2003;Reeves and Stathopoulos, 2009;Lynch and Roth, 2011). Dorsal induces the transcription of Snail and Twist, both of which encode two major proteins in gastrulation that control mitotic arrest, invagination of fated ventral mesoderm and the delamination of mesodermal cells (Stathopoulos and Levine, 2002) (Fig.…”

Mesodermal repression of single-minded in Drosophila embryo is mediated by a cluster of Snail-binding sites proximal to the early promoter

“…The Sim-Tgo heterodimer maintains sim expression by directly binding to a cluster of Sim-Tgo binding sites located in a 5' autoregulatory enhancer element (9). Sequential expression of patterning genes along the dorsal-ventral (DV) axis of the early embryo is produced by a nuclear gradient of the maternal transcription factor Dorsal (Dl), thereby establishing the presumptive mesoderm, mesectoderm, neurogenic ectoderm and dorsal ectoderm (10,11). During early embryogenesis, sim expression begins before the cellular blastoderm stage, but only in a single row of cells along either side of the embryo (2) (Fig.…”