Open AccessA shared ancient enhancer element differentially regulates the bric-a-brac tandem gene duplicates in the developing Drosophila leg
Author(s) -
Henri-Marc Bourbon,
Mikhail H. Benetah,
Emmanuelle Guillou,
Luis Humberto Mojica-Vázquez,
Aissette Baanannou,
Sandra Bernat-Fabre,
Vincent Loubière,
Frédéric Bantignies,
Giacomo Cavalli,
Muriel Boube
Publication year - 2022
Publication title -
plos genetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.587
H-Index - 233
eISSN - 1553-7404
pISSN - 1553-7390
DOI - 10.1371/journal.pgen.1010083
Subject(s) - biology , enhancer , gene duplication , tandem exon duplication , genetics , gene , drosophila melanogaster , regulation of gene expression , crispr , genome , evolutionary biology , gene expression
Gene duplications and transcriptional enhancer emergence/modifications are thought having greatly contributed to phenotypic innovations during animal evolution. Nevertheless, little is known about how enhancers evolve after gene duplication and how regulatory information is rewired between duplicated genes. The Drosophila melanogaster bric-a-brac ( bab ) complex, comprising the tandem paralogous genes bab1 and bab2 , provides a paradigm to address these issues. We previously characterized an intergenic enhancer (named LAE) regulating bab2 expression in the developing legs. We show here that bab2 regulators binding directly the LAE also govern bab1 expression in tarsal cells. LAE excision by CRISPR/Cas9-mediated genome editing reveals that this enhancer appears involved but not strictly required for bab1 and bab2 co-expression in leg tissues. Instead, the LAE enhancer is critical for paralog-specific bab2 expression along the proximo-distal leg axis. Chromatin features and phenotypic rescue experiments indicate that LAE functions partly redundantly with leg-specific regulatory information overlapping the bab1 transcription unit. Phylogenomics analyses indicate that (i) the bab complex originates from duplication of an ancestral singleton gene early on within the Cyclorrhapha dipteran sublineage, and (ii) LAE sequences have been evolutionarily-fixed early on within the Brachycera suborder thus predating the gene duplication event. This work provides new insights on enhancers, particularly about their emergence, maintenance and functional diversification during evolution.