1. RFX2 Is a Major Transcriptional Regulator of Spermiogenesis
- Author
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Kistler, W. Stephen, Baas, Dominique, Lemeille, Sylvain, Paschaki, Marie, Seguin-Estevez, Queralt, Barras, Emmanuèle, Ma, Wenli, Duteyrat, Jean-Luc, Morlé, Laurette, Durand, Bénédicte, and Reith, Walter
- Subjects
Male ,Transcription, Genetic ,lcsh:QH426-470 ,Apoptosis ,Regulatory Factor X Transcription Factors ,ddc:616.07 ,Cyclic AMP Response Element Modulator ,Mice ,Spermatocytes ,Cell Adhesion ,Animals ,Cilia ,Spermatogenesis ,Cytoskeleton ,Infertility, Male ,Mice, Knockout ,TATA-Binding Protein Associated Factors ,Gene Expression Profiling ,Spermatids ,DNA-Binding Proteins ,Mice, Inbred C57BL ,lcsh:Genetics ,Gene Expression Regulation ,Transcription Factor TFIID ,Research Article ,Transcription Factors - Abstract
Spermatogenesis consists broadly of three phases: proliferation of diploid germ cells, meiosis, and finally extensive differentiation of the haploid cells into effective delivery vehicles for the paternal genome. Despite detailed characterization of many haploid developmental steps leading to sperm, only fragmentary information exists on the control of gene expression underlying these processes. Here we report that the RFX2 transcription factor is a master regulator of genes required for the haploid phase. A targeted mutation of Rfx2 was created in mice. Rfx2-/- mice are perfectly viable but show complete male sterility. Spermatogenesis appears to progress unperturbed through meiosis. However, haploid cells undergo a complete arrest in spermatid development just prior to spermatid elongation. Arrested cells show altered Golgi apparatus organization, leading to a deficit in the generation of a spreading acrosomal cap from proacrosomal vesicles. Arrested cells ultimately merge to form giant multinucleated cells released to the epididymis. Spermatids also completely fail to form the flagellar axoneme. RNA-Seq analysis and ChIP-Seq analysis identified 139 genes directly controlled by RFX2 during spermiogenesis. Gene ontology analysis revealed that genes required for cilium function are specifically enriched in down- and upregulated genes showing that RFX2 allows precise temporal expression of ciliary genes. Several genes required for cell adhesion and cytoskeleton remodeling are also downregulated. Comparison of RFX2-regulated genes with those controlled by other major transcriptional regulators of spermiogenesis showed that each controls independent gene sets. Altogether, these observations show that RFX2 plays a major and specific function in spermiogenesis., Author Summary Failure of spermatogenesis, which is presumed to often result from genetic defects, is a common cause of male sterility. Although numerous genes associated with defects in male spermatogenesis have been identified, numerous cases of genetic male infertility remain unelucidated. We report here that the transcription factor RFX2 is a master regulator of gene expression programs required for progression through the haploid phase of spermatogenesis. Male RFX2-deficient mice are completely sterile. Spermatogenesis progresses through meiosis, but haploid cells undergo a complete block in development just prior to spermatid elongation. Gene expression profiling and ChIP-Seq analysis revealed that RFX2 controls key pathways implicated in cilium/flagellum formation, as well as genes implicated in microtubule and vesicle associated transport. The set of genes activated by RFX2 in spermatids exhibits virtually no overlap with those controlled by other known transcriptional regulators of spermiogenesis, establishing RFX2 as an essential new player in this developmental process. RFX2-deficient mice should therefore represent a valuable new model for deciphering the regulatory networks that direct sperm formation, and thereby contribute to the identification of causes of human male infertility.
- Published
- 2015