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Schartl M, Schories S, Wakamatsu Y, Nagao Y, Hashimoto H, Bertin C, Mourot B, Schmidt C, Wilhelm D, Centanin L, Guiguen Y, Herpin A. Sox5 is involved in germ-cell regulation and sex determination in medaka following co-option of nested transposable elements. BMC Biol 2018; 16:16. [PMID: 29378592 PMCID: PMC5789577 DOI: 10.1186/s12915-018-0485-8] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Accepted: 01/11/2018] [Indexed: 12/21/2022] Open
Abstract
Background Sex determination relies on a hierarchically structured network of genes, and is one of the most plastic processes in evolution. The evolution of sex-determining genes within a network, by neo- or sub-functionalization, also requires the regulatory landscape to be rewired to accommodate these novel gene functions. We previously showed that in medaka fish, the regulatory landscape of the master male-determining gene dmrt1bY underwent a profound rearrangement, concomitantly with acquiring a dominant position within the sex-determining network. This rewiring was brought about by the exaptation of a transposable element (TE) called Izanagi, which is co-opted to act as a silencer to turn off the dmrt1bY gene after it performed its function in sex determination. Results We now show that a second TE, Rex1, has been incorporated into Izanagi. The insertion of Rex1 brought in a preformed regulatory element for the transcription factor Sox5, which here functions in establishing the temporal and cell-type-specific expression pattern of dmrt1bY. Mutant analysis demonstrates the importance of Sox5 in the gonadal development of medaka, and possibly in mice, in a dmrt1bY-independent manner. Moreover, Sox5 medaka mutants have complete female-to-male sex reversal. Conclusions Our work reveals an unexpected complexity in TE-mediated transcriptional rewiring, with the exaptation of a second TE into a network already rewired by a TE. We also show a dual role for Sox5 during sex determination: first, as an evolutionarily conserved regulator of germ-cell number in medaka, and second, by de novo regulation of dmrt1 transcriptional activity during primary sex determination due to exaptation of the Rex1 transposable element. Electronic supplementary material The online version of this article (10.1186/s12915-018-0485-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Manfred Schartl
- Physiological Chemistry, Biocenter, University of Würzburg, 97074, Würzburg, Germany.,Comprehensive Cancer Center Mainfranken, University Hospital, 97080, Würzburg, Germany.,Texas Institute for Advanced Study and Department of Biology, Texas A&M University, College Station, TX, 77843, USA
| | - Susanne Schories
- Physiological Chemistry, Biocenter, University of Würzburg, 97074, Würzburg, Germany
| | - Yuko Wakamatsu
- Physiological Chemistry, Biocenter, University of Würzburg, 97074, Würzburg, Germany
| | - Yusuke Nagao
- Bioscience and Biotechnology Center, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, Japan
| | - Hisashi Hashimoto
- Bioscience and Biotechnology Center, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, Japan
| | - Chloé Bertin
- INRA, UR1037 Fish Physiology and Genomics, F-35000, Rennes, France
| | - Brigitte Mourot
- INRA, UR1037 Fish Physiology and Genomics, F-35000, Rennes, France
| | - Cornelia Schmidt
- Physiological Chemistry, Biocenter, University of Würzburg, 97074, Würzburg, Germany
| | - Dagmar Wilhelm
- Department of Anatomy & Neuroscience, University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Lazaro Centanin
- Centre for Organismal Studies (COS), University of Heidelberg, Heidelberg, Germany
| | - Yann Guiguen
- INRA, UR1037 Fish Physiology and Genomics, F-35000, Rennes, France
| | - Amaury Herpin
- Physiological Chemistry, Biocenter, University of Würzburg, 97074, Würzburg, Germany. .,INRA, UR1037 Fish Physiology and Genomics, F-35000, Rennes, France.
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