The role of DE-cadherin during embryonic optic lobe development and larval brain morphogenesis

Cadherins are cell adhesion molecules that play an important role during animal embryogenesis, including during tissue morphogenesis and nervous system development. In this thesis, the role of the Drosophila E-cadherin homologue (DE-cadherin) during the development of the embryonic neuroepithelial optic lobe and larval brain morphogenesis is addressed.;During Drosophila embryonic visual system development, transcription factors and signaling pathways are required for the normal development of this structure. The tyrosine kinase receptor, Epidermal Growth Factor Receptor, is required throughout optic lobe development for cell maintenance. Whereas the transcription factor Atonal and the nuclear hormone receptor Tailless are required for cell fate specification of the larval eye and optic lobe.;The morphogenesis of the optic lobe and larval eye, i.e. the invaginantion of the optic lobe, requires dynamic regulated levels of DE-cadherin. Loss of DE-cadherin leads to optic lobe cells undergoing apoptosis, whereas increased levels of DE-cadherin cause defective invagination of the optic lobe. Data are presented, that implicate a second role for the Epidermal Growth Factor Receptor, namely in the regulating of DE-cadherin mediated cell adhesion during optic lobe morphogenesis.;DE-cadherin is also expressed in the Drosophila larval brain. DE-cadherin is expressed in all neuronal precursors as well as transiently in all neurons produced during larval neurogenesis. DE-cadherin is important for several functions during larval brain development. It is required for division of al neuronal precursor cell and for the normal placement of neuronal cell bodies in the larval brain. Finally DE-cadherin is important for the proper trajectories of larval brain axons.