The Drosophila jing gene is a downstream target in the Trachealess/Tango tracheal pathway

Abstract

Primary branching in the Drosophila trachea is regulated by the Trachealess (Trh) and Tango (Tgo) basic helix-loop-helix-PAS (bHLH-PAS) heterodimers, the POU protein Drifter (Dfr)/Ventral Veinless (Vvl), and the Pointed (Pnt) ETS transcription factor. The jing gene encodes a zinc finger protein also required for tracheal development. Three Trh/Tgo DNA-binding sites, known as CNS midline elements, in 1.5 kb of jing 5′ cis-regulatory sequence (jing1.5) previously suggested a downstream role for jing in the pathway. Here, we show that jing is a direct downstream target of Trh/Tgo and that Vvl and Pnt are also involved in jing tracheal activation. In vivo lacZ enhancer detection assays were used to identify cis-regulatory elements mediating embryonic expression patterns of jing. A 2.8-kb jing enhancer (jing2.8) drove lacZ expression in all tracheal cell lineages, the CNS midline and Engrailed-positive segmental stripes, mimicking endogenous jing expression. A 1.3-kb element within jing2.8 drove expression that was restricted to Engrailed-positive CNS midline cells and segmental ectodermal stripes. Surprisingly, jing1.5-lacZ expression was restricted to tracheal fusion cells despite the presence of consensus DNA-binding sites for bHLH-PAS, ETS, and POU domain transcription factors. Given the absence of Trh/Tgo DNA-binding sites in the jing1.3 enhancer, these results are consistent with previous observations suggesting a combinatorial basis to Trh-/Tgo-mediated transcriptional regulation in the trachea.

Drosophila Jing is part of the breathless fibroblast growth factor receptor positive feedback loop

“…A similarity in tracheal phenotypes among embryos mutant for jing, pnt, and dfr/vvl correlates with a strong dosage sensitivity between these genes. This is also consistent with the regulation of jing expression by pnt and vvl (Morozova et al 2010). The dfr and pnt tracheal phenotypes shown here reveal a requirement in all branches similar to previous characterizations of hypomorphic pnt alleles (Myat et al 2005).…”

“…Therefore, minimal Btl-Gal4 protein levels may be sufficient to induce UASjing-RNAi transgenes. This is supported by the ability of Trh/Tgo to activate some btl mRNA when ectopically expressed in jing, dfr/vvl, and pnt negative cells (Morozova et al 2010). This is also consistent with previous findings that trh/tgo-mediated btl activation is not always dependent on dfr/vvl, as is the case in wild-type tracheal pits (Anderson et al 1996) or on pnt (Ohshiro et al 2002).…”

“…e Protein from whole cell lysates of S2 cells transfected with empty vector; pPac3-tgoFLAG; pPac3-trhHA and co-transfected with pPac3-tgoFLAG and pPac3-trhHA. S2 cells were subjected to immunoprecipitation with anti-HA and Western analysis using antiFlag as probe We propose that Trh/Tgo heterodimers are able to activate minimal btl expression as determined by in vivo and in vitro reporter assays (Morozova et al 2010;this study), resulting in the activation of Pnt (Ohshiro et al 2002). Trh/ Tgo combinatorially activate jing with Pnt and Vvl, allowing Jing to activate maximal btl expression with Trh/ Tgo.…”

Crossveinless is a direct transcriptional target of Trachealess and Tango in Drosophila tracheal precursor cells

“…CME sites in a number of tracheal-specific regulatory elements have been defined [8], and many of these targets of Trh and Tgo are also required for normal tracheal cell development. The targets include the fibroblast growth factor signaling pathway, characterized by the receptor Breathless (Btl), which is a direct transcriptional target of Trh and Tgo [9]; and the jing gene, which encodes a zinc finger transcription factor required for tracheal development [10], and which is regulated by Trh/Tgo [11]. ventral veinless (vvl , also named drifter) , encoding a POU domain transcription factor required for tracheal development [12], can function alongside Trh in the activation of target gene expression [7].…”