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Citrylglutamate synthase deficient male mice are subfertile with impaired histone and transition protein 2 removal in late spermatids. Biochem J 2022; 479:953-972. [PMID: 35419597 DOI: 10.1042/bcj20210844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 04/13/2022] [Accepted: 04/14/2022] [Indexed: 11/17/2022]
Abstract
Chromatin remodelling in spermatids is an essential step in spermiogenesis and involves the exchange of most histones by protamines, which drives chromatin condensation in late spermatids. The gene Rimklb encodes a citrylglutamate synthase highly expressed in testes of vertebrates and the increase of its reaction product, β-citrylglutamate, correlates in time with the appearance of spermatids. Here we show that deficiency in a functional Rimklb gene leads to male subfertility, which could be partially rescued by in vitro fertilization. Rimklb-deficient mice are impaired in a late step of spermiogenesis and produce spermatozoa with abnormally shaped heads and nuclei. Sperm chromatin in Rimklb-deficient mice was less condensed and showed impaired histone to protamine exchange and retained transition protein 2. These observations suggest that citrylglutamate synthase, probably via its reaction product β-citrylglutamate, is essential for efficient chromatin remodelling during spermiogenesis and may be a possible candidate gene for male subfertility or infertility in humans.
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Liu N, Qadri F, Busch H, Huegel S, Sihn G, Chuykin I, Hartmann E, Bader M, Rother F. Kpna6 deficiency causes infertility in male mice by disrupting spermatogenesis. Development 2021; 148:272018. [PMID: 34473250 PMCID: PMC8513612 DOI: 10.1242/dev.198374] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 08/18/2021] [Indexed: 11/20/2022]
Abstract
Spermatogenesis is driven by an ordered series of events, which rely on trafficking of specific proteins between nucleus and cytoplasm. The karyopherin α family of proteins mediates movement of specific cargo proteins when bound to karyopherin β. Karyopherin α genes have distinct expression patterns in mouse testis, implying they may have unique roles during mammalian spermatogenesis. Here, we use a loss-of-function approach to determine specifically the role of Kpna6 in spermatogenesis and male fertility. We show that ablation of Kpna6 in male mice leads to infertility and has multiple cumulative effects on both germ cells and Sertoli cells. Kpna6-deficient mice exhibit impaired Sertoli cell function, including loss of Sertoli cells and a compromised nuclear localization of the androgen receptor. Furthermore, our data demonstrate devastating defects on spermiogenesis, including incomplete sperm maturation and a massive reduction in sperm number, accompanied by disturbed histone-protamine exchange, differential localization of the transcriptional regulator BRWD1 and altered expression of RFX2 target genes. Our work uncovers an essential role of Kpna6 in spermatogenesis and, hence, in male fertility. Summary: Two different mouse models delineate the morphological and functional impact of Kpna6 on spermatogenesis and Sertoli cell function and show that this protein is crucial for fertility in male mice.
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Affiliation(s)
- Na Liu
- Max Delbrück Center for Molecular Medicine, Berlin 13125, Germany
| | | | - Hauke Busch
- Medical Systems Biology Division, Lübeck Institute of Experimental Dermatology and Institute for Cardiogenetics, University of Lübeck, Lübeck 23562, Germany
| | - Stefanie Huegel
- Max Delbrück Center for Molecular Medicine, Berlin 13125, Germany.,Institute for Biology, Center for Structural and Cellular Biology in Medicine, University of Lübeck, Lübeck 23562, Germany
| | - Gabin Sihn
- Max Delbrück Center for Molecular Medicine, Berlin 13125, Germany
| | - Ilya Chuykin
- Max Delbrück Center for Molecular Medicine, Berlin 13125, Germany.,Department of Cell Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, NY 10029-6574, USA
| | - Enno Hartmann
- Institute for Biology, Center for Structural and Cellular Biology in Medicine, University of Lübeck, Lübeck 23562, Germany
| | - Michael Bader
- Max Delbrück Center for Molecular Medicine, Berlin 13125, Germany.,Institute for Biology, Center for Structural and Cellular Biology in Medicine, University of Lübeck, Lübeck 23562, Germany
| | - Franziska Rother
- Max Delbrück Center for Molecular Medicine, Berlin 13125, Germany.,Institute for Biology, Center for Structural and Cellular Biology in Medicine, University of Lübeck, Lübeck 23562, Germany
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