The transcription factor optomotor-blind antagonizes Drosophila haltere growth by repressing decapentaplegic and Hedgehog targets

In Drosophila, decapentaplegic, which codes for a secreted signaling molecule, is activated by the Hedgehog signaling pathway at the anteroposterior compartment border of the two dorsal primordia; the wing and the haltere imaginal discs. In the wing disc, Decapentaplegic and Hedgehog signaling targets are implicated in cell proliferation and cell survival. However, most of their known targets in the wing disc are not expressed in the haltere disc due to their repression by the Hox gene Ultrabithorax. The T-box gene optomotor-blind escapes this repression in the haltere disc, and therefore is expressed in both the haltere and wing discs. Optomotor-blind is a major player during wing development and its function has been intensely investigated in this tissue, however, its role in haltere development has not been reported so far. Here we show that Optomotor-blind function in the haltere disc differs from that in the wing disc. Unlike its role in the wing, Optomotor-blind does not prevent apoptosis in the haltere but rather limits growth by repressing several Decapentaplegic and Hedgehog targets involved both in wing proliferation and in modulating the spread of morphogens similar to Ultrabithorax function but without disturbing Ultrabithorax expressionThis work was supported by grants Biología Fundamental (BFU2011-25987) and Consolider Program (CDS 2007-00008) from the Spanish Ministry of Economy and Commutativity (http://www.mineco.gob.es), by Initial Training Networks (ITN) - Marie Curie Actions (ITN 238186) (http://ec.europa.eu/research/mariecurieactions/ about mca/actions/itn/indexen.htm) and by an institutional grant to Centro Biología Molecular “Severo Ochoa” from the Fundación Ramón Areces (http://fundacionareces.es/fundacionareces). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscrip