D-six4 plays a key role in patterning cell identities deriving from the Drosophila mesoderm

• Published in: Developmental biology 2006-06, Vol.294 (1), p.220-231
• Main Authors: Clark, Ivan B.N., Boyd, Joanna, Hamilton, Graham, Finnegan, David J., Jarman, Andrew P.
• Format: Article
• Language: English
• Subjects: Animals; Body Patterning; Drosophila; Drosophila melanogaster - embryology; Drosophila Proteins - genetics; Drosophila Proteins - physiology; Embryo, Nonmammalian; Eye Proteins - genetics; Gene Expression Regulation, Developmental; Homeodomain Proteins - physiology; Mesoderm; Mesoderm - cytology; Muscles; Nerve Tissue Proteins - physiology; Patterning; Repressor Proteins - genetics; SIX genes; Trans-Activators - genetics; Transcription Factors - physiology; Transcriptional regulation
• ISSN: 0012-1606; 1095-564X
• DOI: 10.1016/j.ydbio.2006.02.044

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.