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Development. 2014 Oct;141(19):3761-71. doi: 10.1242/dev.111005. Epub 2014 Sep 10.

An Org-1-Tup transcriptional cascade reveals different types of alary muscles connecting internal organs in Drosophila.

Author information

1
Université de Toulouse 3, Centre de Biologie du Développement, UMR 5547 CNRS and FRBT, 118 route de Narbonne, Toulouse F-31062, Cedex 09, France.
2
Friedrich-Alexander University of Erlangen-Nürnberg, Department of Biology, Division of Developmental Biology, Staudtstraβe 5, Erlangen 91058, Germany.
3
Friedrich-Alexander University of Erlangen-Nürnberg, Department of Biology, Division of Developmental Biology, Staudtstraβe 5, Erlangen 91058, Germany manfred.frasch@fau.de alain.vincent@univ-tlse3.fr.
4
Université de Toulouse 3, Centre de Biologie du Développement, UMR 5547 CNRS and FRBT, 118 route de Narbonne, Toulouse F-31062, Cedex 09, France manfred.frasch@fau.de alain.vincent@univ-tlse3.fr.

Abstract

The T-box transcription factor Tbx1 and the LIM-homeodomain transcription factor Islet1 are key components in regulatory circuits that generate myogenic and cardiogenic lineage diversity in chordates. We show here that Org-1 and Tup, the Drosophila orthologs of Tbx1 and Islet1, are co-expressed and required for formation of the heart-associated alary muscles (AMs) in the abdomen. The same holds true for lineage-related muscles in the thorax that have not been described previously, which we name thoracic alary-related muscles (TARMs). Lineage analyses identified the progenitor cell for each AM and TARM. Three-dimensional high-resolution analyses indicate that AMs and TARMs connect the exoskeleton to the aorta/heart and to different regions of the midgut, respectively, and surround-specific tracheal branches, pointing to an architectural role in the internal anatomy of the larva. Org-1 controls tup expression in the AM/TARM lineage by direct binding to two regulatory sites within an AM/TARM-specific cis-regulatory module, tupAME. The contributions of Org-1 and Tup to the specification of Drosophila AMs and TARMs provide new insights into the transcriptional control of Drosophila larval muscle diversification and highlight new parallels with gene regulatory networks involved in the specification of cardiopharyngeal mesodermal derivatives in chordates.

KEYWORDS:

Alary muscle development; Drosophila; Islet1; Org-1; Tbx1; Transcriptional cascades; Tup

PMID:
25209244
DOI:
10.1242/dev.111005
[Indexed for MEDLINE]
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