Specification of differentiated adult progenitors via inhibition of endocycle entry in the Drosophila trachea

Under a Creative Commons licenseA population of Drosophila adult tracheal progenitor cells arises from differentiated cells of the larval main trachea that retain the ability to reenter the cell cycle and give rise to the multiple adult tracheal cell types. These progenitors are unique to the second tracheal metamere as homologous cells from other segments, express fizzy-related (fzr), the Drosophila homolog of CDH1 protein of the APC complex, and enter endocycle and do not contribute to adult trachea. Here, we examine the mechanisms for their quiescence and show that they reenter the cell cycle by expression of string/cdc25 through ecdysone. Furthermore, we show that preventing endocycle entry is both necessary and sufficient for these tracheal cells to exhibit markers of adult progenitors, thus modifying their genetic program. Finally, we show that Hox-mediated regulation of fzr expression is responsible for progenitor identity and thus specifies a group of differentiated cells with facultative stem cell features. © 2014 The Authors.N.J.-V.D. was supported by BFU2009-07629 from the Spanish MICINN and NSF PRFB DBI-1308908, J. Cruz was supported by BFU2009-08748 from the Spanish MICINN, and C.d.M. was supported by FPI from the Spanish MICINN. This work has been supported by the Generalitat de Catalunya, the Spanish Ministerio de Ciencia e Innovacion, and its Consolider-Ingenio 2010 program.Peer Reviewe