R7 photoreceptor specification requires Notch activity
| Autor: | Sarah J. Bray, Michael T.D. Cooper |
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| Rok vydání: | 2000 |
| Předmět: |
Transcription
Genetic Cell Notch signaling pathway Context (language use) Cell fate determination Eye General Biochemistry Genetics and Molecular Biology Receptor tyrosine kinase 03 medical and health sciences 0302 clinical medicine Ommatidium medicine Animals Drosophila Proteins 030304 developmental biology Genetics 0303 health sciences Agricultural and Biological Sciences(all) biology Receptors Notch Biochemistry Genetics and Molecular Biology(all) Gene Expression Regulation Developmental Membrane Proteins Proteins Cone cell Cell biology Repressor Proteins medicine.anatomical_structure Notch proteins biology.protein ras Proteins Drosophila Photoreceptor Cells Invertebrate General Agricultural and Biological Sciences 030217 neurology & neurosurgery Signal Transduction |
| Zdroj: | Current biology : CB. 10(23) |
| ISSN: | 0960-9822 |
| Popis: | The eight photoreceptors in each ommatidium of the Drosophila eye are assembled by a process of recruitment [1,2]. First, the R8 cell is singled out, and then subsequent photoreceptors are added in pairs (R2 and R5, R3 and R4, R1 and R6) until the final R7 cell acquires a neuronal fate. R7 development requires the Sevenless receptor tyrosine kinase which is activated by a ligand from R8 [3]. Here, we report that the specification of R7 requires a second signal that activates Notch. We found that a Notch target gene is expressed in R7 shortly after recruitment. When Notch activity was reduced, the cell was misrouted to an R1/R6 fate. Conversely, when activated Notch was present in the R1/R6 cells, it caused them to adopt R7 fates or, occasionally, cone cell fates. In this context, Notch activity appears to act co-operatively, rather than antagonistically, with the receptor tyrosine kinase/Ras pathway in R7 photoreceptor specification. We propose two models: a ratchet model in which Notch would allow cells to remain competent to respond to sequential rounds of Ras signalling, and a combinatorial model in which Notch and Ras signalling would act together to regulate genes that determine cell fate. |
| Databáze: | OpenAIRE |
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