Role of Helix-Loop-Helix Proteins in Drosophila Neurogenesis

Abstract

The development of the nervous system in invertebrate and vertebrate systems is initiated by the determination of a subset of neuroectodermal cells to become neuronal precursor cells. In this process, neuroectodermal cells choose between two principal developmental pathways and subsequently differentiate into either neuronal or epidermal precursors. In the early developmental processes of spatial subdivision and segmentation in Drosophila (and to some degree in vertebrate systems), DNA-binding proteins containing either the homeobox or zinc finger domain are instrumental. These classes of transcription factors have not been found to be regulators of the initial steps of neurogenesis. In contrast, several members of a recently defined class of DNA-binding proteins containing the so-called helix-loop-helix (HLH) domain play an important role in the choice between neurogenesis and epidermogenesis in Drosophila (Ghysen and Dambly-Chaudiere 1989; Knust and Campos-Ortega 1989). Other HLH-domain-containing proteins also appear to control cell fate, such as mesoderm formation (Thisse et...