title: Repression of Drosophila photoreceptor cell fate through cooperative action of two transcriptional repressors Yan and Tramtrack.
abstract: The Drosophila yan gene encodes an E twenty-six (ETS) domain nuclear protein with a transcription repressor activity that can be downregulated through phosphorylation by mitogen-activated protein kinase (MAPK). Before photoreceptor precursor cells commit to a particular cell fate, Yan is required to maintain them in an undifferentiated state. We report here identification of tramtrack (ttk) mutations that act as dominant enhancers of yan. We show that ttk synergistically interacts with yan to inhibit the R7 photoreceptor cell fate. Since ttk products are nuclear proteins with zinc-finger DNA-binding motifs, yan and ttk represent two nuclear regulators essential for the control of cellular competence for neural differentiation. Reduction of either yan or ttk activity suppresses eye phenotypes of the kinase suppressor of ras (ksr) gene mutation, which is consistent with the involvement of yan and ttk in the Ras/MAPK pathway.
authors.affiliation: Department of Biology, The Pennsylvania State University, University Park 16802, USA. ZCL1@psu.edu
authors.forename: Z C
authors.initials: ZC
authors.lastname: Lai
authors.forename: M
authors.initials: M
authors.lastname: Fetchko
authors.forename: Y
authors.initials: Y
authors.lastname: Li
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000502:physiology; D004330:Drosophila / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D029721:Drosophila Proteins; D005136:Eye Proteins / Q000235:genetics / Q000502:physiology*; D009154:Mutation; D010641:Phenotype; D017956:Photoreceptor Cells, Invertebrate / Q000166:cytology*; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D016335:Zinc Fingers
chemical_list: C076188:AOP protein, Drosophila; D029721:Drosophila Proteins; D005136:Eye Proteins; D012097:Repressor Proteins; C075878:ttk protein, Drosophila