Tramtrack69 is required for the early repression of tailless expression

Abstract

During embryogenesis, the activated Torso receptor tyrosine kinase (TOR RTK) pathway activates tailless (tll) expression by a relief-of-repression mechanism. Various lines of evidence have suggested that multiple factors are required for this repression. We show that Tramtrack69 (TTK69) binds to two sites within tll cis-regulatory DNA, TC2 and TC5, and that TTK69 is phosphorylated by mitogen activated protein kinase. In embryos lacking maternal ttk69 activity, the expression of both endogenous tll and lacZ driven by the tll minimal regulatory region (tll-MRR) are expanded. Further, in wild-type embryos, the tll-MRR mutated in TC5 drives uniform lacZ expression before late stage 4. We conclude that TTK69 is required for early (before the end of stage 4) repression of tll transcription.

Following the ‘tracks’: Tramtrack69 regulates epithelial tube expansion in the Drosophila ovary through Paxillin, Dynamin, and the homeobox protein Mirror

“…The first proposed TTK69 motifs were based on binding interactions with the fushi tarazu ( ftz ) promoter (TTATCCG, Harrison and Travers, 1990; TGCNAGGACNT, Brown et al, 1991); or on interactions with both ftz and even-skipped ( eve ). This knowledge facilitated analysis of TTK69 binding sites in the tailless ( tll ) promoter (TCCT; Chen et al, 2002). A weighted TTK69 motif, ascertained through bacterial one-hybrid and DNAseI-footprinting assays, expanded upon the previous TCCT motif (∼ttaTCCTg; Kulakovskiy and Makeev, 2009).…”

Tramtrack Is Genetically Upstream of Genes Controlling Tracheal Tube Size in Drosophila

“…Again, this is probably due to different co-regulators that dictate the directionality of an expression change. Although Ttk is widely believed to act as transcriptional repressor [3], [5], [9], [14], the analysis of genome-wide binding data has suggested alternative roles for many transcription factors, and a recent theoretical study implies that most transcription factors may act in different directions [27].…”

Antagonistic action of Bicoid and the repressor Capicua determines the spatial limits of Drosophila head gene expression domains

“…Thus, the anteriormost Bcd target genes are not dependent on Tor-mediated phosphorylation of Bcd. It is likely that Tor downregulates a set of partially redundant repressors at the termini, including Grainyhead, Trithorax-like (16), Tramtrack69 (45), and Female Sterile (1) Homeotic (46), gradually restricting their activities to the central region, which results in Tor-dependent relief of repression (16). The available evidence supports the argument that mirror image duplications that are caused by uniform expression of Bcd are the result of the spatial restriction of repressors by Tor activity as exemplified here for Cic.…”