Delta/Notch and Boss/Sevenless signals act combinatorially to specify the Drosophila R7 photoreceptor.
The R7 photoreceptor, a unique cell type within the Drosophila ommatidium, was initially proposed to be specified by two distinct signals from neighboring cells, one from the R8 photoreceptor and another from the R1/6 photoreceptor pair. The R8-to-R7 signal is the transmembrane ligand Bride of Sevenless (Boss), which is received by the receptor tyrosine kinase Sevenless (Sev) and transduced via Ras activation within the presumptive R7 cell. However, the identity of the R1/6-to-R7 signal has remained elusive. Here, we present evidence that the transmembrane ligand Delta (Dl), expressed by the R1/6 pair, activates the receptor Notch (N) in the presumptive R7 cell and constitutes the postulated R1/6-to-R7 signal required in combination with the Boss/Sev signal to specify the R7 fate.
Tomlinson
A
A
Department of Genetics and Development, Columbia University, College of Physicians and Surgeons, New York, New York 10032, USA. tomlinson@cuccfa.ccc.columbia.edu
Struhl
G
G
D000818:Animals; D030801:Animals, Genetically Modified; D002454:Cell Differentiation; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D005136:Eye Proteins / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D047908:Intracellular Signaling Peptides and Proteins; D008024:Ligands; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008954:Models, Biological; D009030:Mosaicism / Q000235:genetics; D017956:Photoreceptor Cells, Invertebrate / Q000378:metabolism*; D020794:Receptor Protein-Tyrosine Kinases; D051880:Receptors, Notch; D018000:Receptors, Peptide; D015398:Signal Transduction; D019076:Transgenes / Q000235:genetics
D029721:Drosophila Proteins; D005136:Eye Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008024:Ligands; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; C497759:N protein, Drosophila; D051880:Receptors, Notch; D018000:Receptors, Peptide; C072141:boss protein, Drosophila; C064045:delta protein; D020794:Receptor Protein-Tyrosine Kinases; C056737:sev protein, Drosophila