title: D-six4 plays a key role in patterning cell identities deriving from the Drosophila mesoderm.
abstract: Patterning of the Drosophila embryonic mesoderm requires the regulation of cell type-specific factors in response to dorsoventral and anteroposterior axis information. For the dorsoventral axis, the homeodomain gene, tinman, is a key patterning mediator for dorsal mesodermal fates like the heart. However, equivalent mediators for more ventral fates are unknown. We show that D-six4, which encodes a Six family transcription factor, is required for the appropriate development of most cell types deriving from the non-dorsal mesoderm - the fat body, somatic cells of the gonad, and a specific subset of somatic muscles. Misexpression analysis suggests that D-Six4 and its likely cofactor, Eyes absent, are sufficient to impose these fates on other mesodermal cells. At stage 10, the mesodermal expression patterns of D-six4 and tin are complementary, being restricted to the dorsal and non-dorsal regions respectively. Our data suggest that D-six4 is a key mesodermal patterning mediator at this stage that regulates a variety of cell-type-specific factors and hence plays an equivalent role to tin. At stage 9, however, D-six4 and tin are both expressed pan-mesodermally. At this stage, tin function is required for full D-six4 expression. This may explain the known requirement for tin in some non-dorsal cell types.
authors.affiliation: Centre for Integrative Physiology, University of Edinburgh, George Square, Edinburgh EH8 9XD, UK.
authors.forename: Ivan B N
authors.initials: IB
authors.lastname: Clark
authors.forename: Joanna
authors.initials: J
authors.lastname: Boyd
authors.forename: Graham
authors.initials: G
authors.lastname: Hamilton
authors.forename: David J
authors.initials: DJ
authors.lastname: Finnegan
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Jarman
mesh_terms: D000818:Animals; D019521:Body Patterning; D029721:Drosophila Proteins / Q000235:genetics / Q000502:physiology*; D004331:Drosophila melanogaster / Q000196:embryology; D004625:Embryo, Nonmammalian; D005136:Eye Proteins / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000502:physiology*; D008648:Mesoderm / Q000166:cytology*; D009132:Muscles; D009419:Nerve Tissue Proteins / Q000502:physiology*; D012097:Repressor Proteins / Q000235:genetics; D015534:Trans-Activators / Q000235:genetics; D014157:Transcription Factors / Q000502:physiology*
chemical_list: D029721:Drosophila Proteins; D005136:Eye Proteins; D018398:Homeodomain Proteins; D009419:Nerve Tissue Proteins; D012097:Repressor Proteins; C434485:Six4 protein, Drosophila; D015534:Trans-Activators; D014157:Transcription Factors; C092694:eya protein, Drosophila; C102933:tin protein, Drosophila