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Bourbon HMG, Benetah MH, Guillou E, Mojica-Vazquez LH, Baanannou A, Bernat-Fabre S, Loubiere V, Bantignies F, Cavalli G, Boube M. A shared ancient enhancer element differentially regulates the bric-a-brac tandem gene duplicates in the developing Drosophila leg. PLoS Genet 2022; 18:e1010083. [PMID: 35294439 PMCID: PMC8959175 DOI: 10.1371/journal.pgen.1010083] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 03/28/2022] [Accepted: 02/07/2022] [Indexed: 11/18/2022] Open
Abstract
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.
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Affiliation(s)
- Henri-Marc G. Bourbon
- Center for Integrative Biology, Molecular Cellular and Developmental (MCD) Biology Unit, Federal University of Toulouse, Toulouse, France
| | - Mikhail H. Benetah
- Center for Integrative Biology, Molecular Cellular and Developmental (MCD) Biology Unit, Federal University of Toulouse, Toulouse, France
| | - Emmanuelle Guillou
- Center for Integrative Biology, Molecular Cellular and Developmental (MCD) Biology Unit, Federal University of Toulouse, Toulouse, France
| | - Luis Humberto Mojica-Vazquez
- Center for Integrative Biology, Molecular Cellular and Developmental (MCD) Biology Unit, Federal University of Toulouse, Toulouse, France
| | - Aissette Baanannou
- Center for Integrative Biology, Molecular Cellular and Developmental (MCD) Biology Unit, Federal University of Toulouse, Toulouse, France
| | - Sandra Bernat-Fabre
- Center for Integrative Biology, Molecular Cellular and Developmental (MCD) Biology Unit, Federal University of Toulouse, Toulouse, France
| | - Vincent Loubiere
- Institute of Human Genetics, University of Montpellier, CNRS Montpellier, France
| | - Frédéric Bantignies
- Institute of Human Genetics, University of Montpellier, CNRS Montpellier, France
| | - Giacomo Cavalli
- Institute of Human Genetics, University of Montpellier, CNRS Montpellier, France
| | - Muriel Boube
- Center for Integrative Biology, Molecular Cellular and Developmental (MCD) Biology Unit, Federal University of Toulouse, Toulouse, France
- * E-mail:
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