Specification of Drosophila aCC motoneuron identity by a genetic cascade involving even-skipped, grain and zfh1.
During nervous system development, combinatorial codes of regulators act to specify different neuronal subclasses. However, within any given subclass, there exists a further refinement, apparent in Drosophila and C. elegans at single-cell resolution. The mechanisms that act to specify final and unique neuronal cell fates are still unclear. In the Drosophila embryo, one well-studied motoneuron subclass, the intersegmental motor nerve (ISN), consists of seven unique motoneurons. Specification of the ISN subclass is dependent upon both even-skipped (eve) and the zfh1 zinc-finger homeobox gene. We find that ISN motoneurons also express the GATA transcription factor Grain, and grn mutants display motor axon pathfinding defects. Although these three regulators are expressed by all ISN motoneurons, these genes act in an eve-->grn-->zfh1 genetic cascade unique to one of the ISN motoneurons, the aCC. Our results demonstrate that the specification of a unique neuron, within a given subclass, can be governed by a unique regulatory cascade of subclass determinants.
INSERM U 583, INM-Hopital St Eloi, 80 rue Augustin Fliche, 34091 Montpellier Cedex 5, France.
Alain
A
Garces
Stefan
S
Thor
D000818:Animals; D001369:Axons / Q000378:metabolism; D002454:Cell Differentiation / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000502:physiology; D004330:Drosophila / Q000166:cytology / Q000196:embryology* / Q000235:genetics; D029721:Drosophila Proteins / Q000235:genetics* / Q000502:physiology; D050980:GATA Transcription Factors / Q000235:genetics* / Q000502:physiology; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000235:genetics* / Q000502:physiology; D007395:Interneurons / Q000166:cytology / Q000378:metabolism; D009046:Motor Neurons / Q000166:cytology* / Q000378:metabolism; D051880:Receptors, Notch / Q000502:physiology; D012097:Repressor Proteins / Q000235:genetics* / Q000502:physiology; D015398:Signal Transduction / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics* / Q000502:physiology
D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D050980:GATA Transcription Factors; D018398:Homeodomain Proteins; C497759:N protein, Drosophila; D051880:Receptors, Notch; D012097:Repressor Proteins; D014157:Transcription Factors; C052837:eve protein, Drosophila; C096148:grn protein, Drosophila; C081010:zfh1 protein, Drosophila