Major spliceosome defects cause male infertility and are associated with nonobstructive azoospermia in humans

Processing of pre-mRNA into mRNA is an important regulatory mechanism in eukaryotes that is mediated by the spliceosome, a huge and dynamic ribonucleoprotein complex. Splicing defects are implicated in a spectrum of human disease, but the underlying mechanistic links remain largely unresolved.

Using a genome-wide association approach, we have recently identified single nucleotide polymorphisms in humans that associate with nonobstructive azoospermia (NOA), a common cause of male infertility. Here, using genetic manipulation of corresponding candidate loci inDrosophila, we show that the spliceosome component SNRPA1/U2A is essential for male fertility. Loss of U2A in germ cells of theDrosophilatestis does not affect germline stem cells, but does result in the accumulation of mitotic spermatogonia that fail to differentiate into spermatocytes and mature sperm. Lack of U2A causes insufficient splicing of mRNAs required for the transition of germ cells from proliferation to differentiation. We show that germ cell-specific disruption of other components of the major spliceosome manifests with the same phenotype, demonstrating that mRNA processing is required for the differentiation of spermatogonia. This requirement is conserved, and expression of human SNRPA1 fully restores spermatogenesis in U2A mutant flies. We further report that several missense mutations in human SNRPA1 that inhibit the assembly of the major spliceosome dominantly disrupt spermatogonial differentiation inDrosophila.Collectively, our findings uncover a conserved and specific requirement for the major spliceosome during the transition from spermatogonial proliferation to differentiation in the male testis, suggesting that spliceosome defects affecting the differentiation of human spermatogonia contribute to NOA.

Proceedings of the National Academy of Sciences of the United States of America. 2016 Mar 28 [Epub ahead of print]

Hao Wu, Liwei Sun, Yang Wen, Yujuan Liu, Jun Yu, Feiyu Mao, Ya Wang, Chao Tong, Xuejiang Guo, Zhibin Hu, Jiahao Sha, Mingxi Liu, Laixin Xia

State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing 210029, People's Republic of China; Department of Histology and Embryology, Nanjing Medical University, Nanjing 210029, People's Republic of China;, Key Laboratory of Zebrafish Modeling and Drug Screening for Human Diseases of Guangdong Higher Education Institutes, Department of Developmental Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, People's Republic of China; State Key Laboratory of Biomembrane and Membrane Biotechnology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, People's Republic of China;, State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing 210029, People's Republic of China; Department of Epidemiology and Biostatistics, School of Public Health, Nanjing Medical University, Nanjing 211166, People's Republic of China;, State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing 210029, People's Republic of China; Department of Histology and Embryology, Nanjing Medical University, Nanjing 210029, People's Republic of China;, State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing 210029, People's Republic of China; Department of Histology and Embryology, Nanjing Medical University, Nanjing 210029, People's Republic of China;, Key Laboratory of Zebrafish Modeling and Drug Screening for Human Diseases of Guangdong Higher Education Institutes, Department of Developmental Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, People's Republic of China; State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, People's Republic of China;, State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing 210029, People's Republic of China; Department of Histology and Embryology, Nanjing Medical University, Nanjing 210029, People's Republic of China;, Life Sciences Institute and Innovation Center for Cell Biology, Zhejiang University, Hangzhou 310058, People's Republic of China., State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing 210029, People's Republic of China; Department of Histology and Embryology, Nanjing Medical University, Nanjing 210029, People's Republic of China;, State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing 210029, People's Republic of China; Department of Epidemiology and Biostatistics, School of Public Health, Nanjing Medical University, Nanjing 211166, People's Republic of China;, State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing 210029, People's Republic of China; Department of Histology and Embryology, Nanjing Medical University, Nanjing 210029, People's Republic of China;, State Key Laboratory of Reproductive Medicine, Nanjing Medical University, Nanjing 210029, People's Republic of China; Department of Histology and Embryology, Nanjing Medical University, Nanjing 210029, People's Republic of China; Key Laboratory of Zebrafish Modeling and Drug Screening for Human Diseases of Guangdong Higher Education Institutes, Department of Developmental Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, People's Republic of China 

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