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Dev Biol. 2014 Nov 1;395(1):131-43. doi: 10.1016/j.ydbio.2014.08.021. Epub 2014 Aug 27.

Co-regulation of invected and engrailed by a complex array of regulatory sequences in Drosophila.

Author information

1
Program in Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, United States.
2
Program in Genomics of Differentiation, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, United States. Electronic address: jkassis@mail.nih.gov.

Abstract

invected (inv) and engrailed (en) form a gene complex that extends about 115 kb. These two genes encode highly related homeodomain proteins that are co-regulated in a complex manner throughout development. Our dissection of inv/en regulatory DNA shows that most enhancers are spread throughout a 62 kb region. We used two types of constructs to analyze the function of this DNA: P-element based reporter constructs with small pieces of DNA fused to the en promoter driving lacZ expression and large constructs with HA-tagged en and inv inserted in the genome with the phiC31 system. In addition, we generated deletions of inv and en DNA in situ and assayed their effects on inv/en expression. Our results support and extend our knowledge of inv/en regulation. First, inv and en share regulatory DNA, most of which is flanking the en transcription unit. In support of this, a 79-kb HA-en transgene can rescue inv en double mutants to viable, fertile adults. In contrast, an 84-kb HA-inv transgene lacks most of the enhancers for inv/en expression. Second, there are multiple enhancers for inv/en stripes in embryos; some of these may be redundant but others play discrete roles at different stages of embryonic development. Finally, no small reporter construct gave expression in the posterior compartment of imaginal discs, a hallmark of inv/en expression. Robust expression of HA-en in the posterior compartment of imaginal discs is evident from the 79-kb HA-en transgene, while a 45-kb HA-en transgene gives weaker, variable imaginal disc expression. We suggest that the activity of the imaginal disc enhancer(s) is dependent on the chromatin structure of the inv/en domain.

KEYWORDS:

Enhancers; Gene expression; Gene regulation; Segmentation

PMID:
25172431
PMCID:
PMC4189978
DOI:
10.1016/j.ydbio.2014.08.021
[Indexed for MEDLINE]
Free PMC Article

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