MicroRNA miR-7 contributes to the control of Drosophila wing growth.

Background: The control of organ growth is critical for correct animal development. From flies to mammals, the mechanisms regulating growth are conserved and the role of microRNAs in this process is emerging. The conserved miR-7 has been described to control several aspects of development.

Results: Here, we have analyzed the function of miR-7 during Drosophila wing development. We found that loss of miR-7 function results in a reduction of wing size and produces wing cells that are smaller than wild type cells. We also found that loss of miR-7 function interferes with the cell cycle by affecting the G1 to S phase transition. Further, we present evidence that miR-7 is expressed in the wing imaginal discs and that the inactivation of miR-7 increases the expression of Cut and Senseless proteins in wing discs. Finally, our results show that the simultaneous inactivation of miR-7 and either cut, Notch, or dacapo rescues miR-7 loss of function wing size reduction phenotype.

Conclusions: The results from this work reveal, for the first time, that miR-7 functions to regulate Drosophila wing growth by controlling cell cycle phasing and cell mass through its regulation of the expression of dacapo and the Notch signaling pathway.