Evolving enhancer-promoter interactions within the tinman complex of the flour beetle, Tribolium castaneum. Author Jessica Cande, Vivek Chopra, Michael Levine Publication Year 2009 Type Journal Article Abstract Modifications of cis-regulatory DNAs, particularly enhancers, underlie changes in gene expression during animal evolution. Here, we present evidence for a distinct mechanism of regulatory evolution, whereby a novel pattern of gene expression arises from altered gene targeting of a conserved enhancer. The tinman gene complex (Tin-C) controls the patterning of dorsal mesodermal tissues, including the dorsal vessel or heart in Drosophila. Despite broad conservation of Tin-C gene expression patterns in the flour beetle (Tribolium castaneum), the honeybee (Apis mellifera) and the fruit fly (Drosophila melanogaster), the expression of a key pericardial determinant, ladybird, is absent from the dorsal mesoderm of Tribolium embryos. Evidence is presented that this loss in expression is replaced by expression of C15, the neighboring gene in the complex. This switch in expression from ladybird to C15 appears to arise from an inversion within the tinman complex, which redirects a conserved ladybird 3' enhancer to regulate C15. In Drosophila, this enhancer fails to activate C15 expression owing to the activity of an insulator at the intervening ladybird early promoter. By contrast, a chromosomal inversion allows the cardiac enhancer to bypass the ladybird insulator in Tribolium. Given the high frequency of genome rearrangements in insects, it is possible that such enhancer switching might be widely used in the diversification of the arthropods. Keywords Animals, Gene Expression Regulation, Developmental, Molecular Sequence Data, Enhancer Elements, Genetic, Drosophila melanogaster, Trans-Activators, Conserved Sequence, Sequence Alignment, Promoter Regions, Genetic, Repressor Proteins, Amino Acid Sequence, Insect Proteins, Bees, Tribolium Journal Development Volume 136 Issue 18 Pages 3153-60 Date Published 09/2009 Alternate Journal Development Google ScholarBibTeXEndNote X3 XML