ladybird, a tandem of homeobox genes that maintain late wingless expression in terminal and dorsal epidermis of the Drosophila embryo

• Published in: Development (Cambridge) Vol. 124; no. 1; pp. 91 - 100
• Main Authors: Jagla, K, Jagla, T, Heitzler, P, Dretzen, G, Bellard, F, Bellard, M
• Format: Journal Article
• Language: English
• Published: England The Company of Biologists Limited 01-01-1997
• Subjects: Amino Acid Sequence; Animals; Chromosome Walking; Cloning, Molecular; DNA-Binding Proteins - biosynthesis; DNA-Binding Proteins - chemistry; DNA-Binding Proteins - genetics; Drosophila; Drosophila - embryology; Drosophila - genetics; Drosophila Proteins; Embryo, Nonmammalian - physiology; Epidermal Cells; Epidermis - physiology; Gene Expression Regulation, Developmental; Genes, Homeobox; Genes, Insect; Homeodomain Proteins - biosynthesis; Homeodomain Proteins - chemistry; Homeodomain Proteins - genetics; In Situ Hybridization; Molecular Sequence Data; Nuclear Proteins - biosynthesis; Nuclear Proteins - chemistry; Polymerase Chain Reaction; Recombinant Proteins - biosynthesis; Recombinant Proteins - chemistry; Sequence Homology, Amino Acid; Transcription Factors - biosynthesis; Transcription Factors - chemistry; Transcription Factors - genetics
• ISSN: 0950-1991; 1477-9129
• DOI: 10.1242/dev.124.1.91

ladybird early and ladybird late genes, tandemly located in the Drosophila 93E homeobox gene cluster, encode highly related homeodomain-containing transcription factors. Here we report the cloning of the complete cDNA sequences of both genes and a study of their expression and regulatory interactions with the segment polarity gene wingless in the epidermis. ladybird genes are co-expressed with wingless in epidermal cells close to the posterior parasegmental boundaries and in terminal regions of the body. In mutant embryos with altered wingless function, transcription of ladybird early and ladybird late is changed; it disappears completely from the epidermis in wingless-embryos, indicating wingless-dependence. After 6 hours of development, wingless expression is maintained by gooseberry in the ventral epidermis. However, in the dorsal epidermis and the terminal regions of the body, expression of wingless is independent of gooseberry but requires a wingless-ladybird regulatory feedback loop. Loss of ladybird function reduces the number of wingless-expressing cells in dorsal epidermis and leads to complete inactivation of wingless in the anal plate. Consequently, mutant ladybird embryos fail to develop anal plates and ubiquitous embryonic expression of either one or both ladybird genes leads to severe defects of the dorsal cuticle. Lack of late wingless expression and anal plate formation can be rescued with the use of a heat-shock-ladybird transgene.