Induction in the developing compound eye of Drosophila: multiple mechanisms restrict R7 induction to a single retinal precursor cell.
The development of the Drosophila R7 photoreceptor cell is determined by a specific inductive interaction between the R8 photoreceptor cell and a single neighboring precursor cell. This process is mediated by bride of sevenless (boss), a cell-surface bound ligand, and the sevenless (sev) tyrosine kinase receptor. The boss ligand is expressed specifically on the surface of the R8 cell, whereas the sev receptor is expressed on 5 cells contacting the developing R8 cell and other cells not in contact with R8. By altering the spatial and temporal expression of boss, we demonstrate that sev-expressing cells that do not contact R8 can assume an R7 cell fate. By contrast, the sev-expressing precursor cells to the R1-R6 photoreceptor cells that do contact R8 are nonresponsive to the inductive cue. Using the rough and Nspl mutations, we demonstrate that an early commitment to an R1-R6 cell fate blocks the pathway of sev activation in these cells.
Van Vactor
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DL
Howard Hughes Medical Institute, Department of Biological Chemistry, UCLA School of Medicine 90024-1737.
Cagan
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RL
Krämer
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H
Zipursky
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SL
D000818:Animals; D003001:Cloning, Molecular; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000196:embryology*; D004627:Embryonic Induction; D005123:Eye / Q000196:embryology; D005136:Eye Proteins / Q000502:physiology*; D015870:Gene Expression; D008024:Ligands; D008562:Membrane Glycoproteins / Q000502:physiology*; D008565:Membrane Proteins / Q000502:physiology*; D009474:Neurons / Q000166:cytology; D010786:Photoreceptor Cells / Q000166:cytology / Q000196:embryology*; D011505:Protein-Tyrosine Kinases / Q000502:physiology; D020794:Receptor Protein-Tyrosine Kinases; D018000:Receptors, Peptide
D029721:Drosophila Proteins; D005136:Eye Proteins; D008024:Ligands; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D018000:Receptors, Peptide; C072141:boss protein, Drosophila; D011505:Protein-Tyrosine Kinases; D020794:Receptor Protein-Tyrosine Kinases; C056737:sev protein, Drosophila