FOXO is the Mediator Linking Temporal Differentiation and the Insulin Signaling Pathway

The timing of differentiation is crucial for the correct development of an organism, because specific pathways can be used reiteratively to differentiate cells. Until recently, the molecular mechanism behind the temporal control of differentiation has remained elusive. Bateman and McNeill (2004) revealed a novel role for the insulin/insulin-like growth factor receptor (InR) pathway in regulating the timing of differentiation in neuronal photoreceptor cells in the Drosophila compound eye. The link between the InR pathway and temporal differentiation is significant, because of the implication that external factors, e.g. nutrition, are tightly coupled to the timing of differentiation. This proposal tests the hypothesis that FOXO, a crucial component of the InR pathway, mediates the regulation of developmental timing. The aims are the following: 1. Observe if dFOXO mutants affect temporal differentiation in the Drosophila eye. 2. Perform epistasis experiments to determine if dFOXO is downstream of other insulin signaling components. 3. Analyze the downstream targets of dFOXO that may play a role in neuronal differentiation.