The proneural gene amos promotes multiple dendritic neuron formation in the Drosophila peripheral nervous system

In the Drosophila peripheral nervous system, proneural genes direct the for mation of different types of sensory organs. Here, we show that amos is a n ovel proneural gene that promotes multiple dendritic (MD) neuron formation. amos encodes a basic-helix-loop-helix (bHLH) protein of the Atonal family. During embryonic development, amos is expressed in patches of ectodermal c ells, and the expression is quickly restricted to sensory organ precursors. Loss of amos function eliminates MD neurons that remain in ASC;atonal muta nts. Misexpression of amos generates ectopic MD and other types of neurons. Amos interacts with the ubiquitously expressed Daughterless protein in viv o and in vitro. Our final misexpression experiments suggest that a domain l ocated outside the DNA-binding domain of Amos determines the MD neuronal sp ecificity.