FOXO regulates cell fate specification of Drosophila ventral olfactory projection neurons

Abstract

Diverse types of neurons must be specified in the developing brain to form the functional neural circuits that are necessary for the execution of daily tasks. Here, we describe the participation of Forkhead box class O (FOXO) in cell fate specification of a small subset of Drosophila ventral olfactory projection neurons (vPNs). Using the two-color labeling system, twin-spot MARCM, we determined the temporal birth order of each vPN type, and this characterization served as a foundation to investigate regulators of cell fate specification. Flies deficient for chinmo, a known temporal cell fate regulator, exhibited a partial loss of vPNs, suggesting that the gene plays a complex role in specifying vPN cell fate and is not the only regulator of this process. Interestingly, loss of foxo function resulted in the precocious appearance of late-born vPNs in place of early-born vPNs, whereas overexpression of constitutively active FOXO caused late-born vPNs to take on a morphology reminiscent of earlier born vPNs. Taken together, these data suggest that FOXO temporally regulates vPN cell fate specification. The comprehensive identification of molecules that regulate neuronal fate specification promises to provide a better understanding of the mechanisms governing the formation of functional brain tissue.

Keywords:

• Ventral olfactory projection neuron
• cell fate specification
• FOXO
• chinmo

Acknowledgements

We thank the TRiP at Harvard Medical School (NIH/NIGMS R01-GM084947) for providing the transgenic RNAi fly stocks used in this study. We also thank Drs. Alex Keene and Duncan Wright for critical reading of the manuscript.

Disclosure statement

The authors have declared that there are no competing interests exist.

Additional information

Funding

This work was supported by the Ministry of Science and Technology (MOST103-2321-B-001–023) and the Institute of Cellular and Organismic Biology, Academia Sinica, Taiwan.