title: Drosophila retinal pigment cell death is regulated in a position-dependent manner by a cell memory gene.
abstract: The stereotyped organization of the Drosophila compound eye depends on the elimination by apoptosis of about 25% of the inter-ommatidial pigment cell precursors (IOCs) during metamorphosis. This program of cell death is under antagonistic effects of the Notch and the EGFR pathways. In addition, uncharacterized positional cues may underlie death versus survival choices among IOCs. Our results provide new genetic evidences that cell death is regulated in a position- dependent manner in the eye. We show that mutations in Trithorax-like (Trl) and lola-like/batman specifically block IOC death during eye morphogenesis. These genes share characteristics of both Polycomb-Group and trithorax-Group genes, in that they are required for chromatin-mediated repression and activation of Hox genes. However, Trl function in triggering IOC death is independent from a function in repressing Hox gene expression during eye development. Analysis of mosaic ommatidiae containing Trl mutant cells revealed that Trl function for IOC death is required in cone cells. Strikingly, cell death suppression in Trl mutants depends on the position of IOCs. Our results further support a model whereby death of IOCs on the oblique sides of ommatidiae requires Trl-dependent reduction of a survival signal, or an increase of a death signal, emanating from cone cells. Trl does not have the same effect on horizontal IOCs whose survival seems to involve additional topological constraints.
authors.affiliation: CNRS - UMR 8159, LGBC, Université de Versailles St Quentin, Versailles, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Dos-Santos
authors.forename: Thomas
authors.initials: T
authors.lastname: Rubin
authors.forename: Fabienne
authors.initials: F
authors.lastname: Chalvet
authors.forename: Pierre
authors.initials: P
authors.lastname: Gandille
authors.forename: Frederic
authors.initials: F
authors.lastname: Cremazy
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Leroy
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Boissonneau
authors.forename: Laurent
authors.initials: L
authors.lastname: Théodore
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000235:genetics* / Q000502:physiology; D015415:Biomarkers / Q000378:metabolism; D004330:Drosophila / Q000235:genetics* / Q000502:physiology; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism; D066246:ErbB Receptors / Q000235:genetics / Q000378:metabolism; D005123:Eye / Q000254:growth & development / Q000648:ultrastructure; D018507:Gene Expression Regulation, Developmental; D017344:Genes, Insect; D009024:Morphogenesis; D009154:Mutation; D010857:Pigment Epithelium of Eye / Q000502:physiology*; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism; D011679:Pupa / Q000254:growth & development; D018010:Receptors, Invertebrate Peptide / Q000235:genetics / Q000378:metabolism; D051880:Receptors, Notch / Q000235:genetics / Q000378:metabolism; D012160:Retina / Q000166:cytology / Q000502:physiology; D019076:Transgenes
chemical_list: D015415:Biomarkers; D029721:Drosophila Proteins; C497759:N protein, Drosophila; D018010:Receptors, Invertebrate Peptide; D051880:Receptors, Notch; D011494:Protein Kinases; C066532:Egfr protein, Drosophila; D066246:ErbB Receptors