Spermatogenesis And Sertoli Cell Only Syndrome

Spermatogenesis is a sophisticatedbiological process by which diploid precursor cells undergo cell division and differentiation to form sperm, including PGCs specification, migration, proliferation and differentiation; gonocytes proliferation、 quiescence and migration; SSCs self-renewal and differentiation; mitosis to meiosis transition; meiosis and spermiogenesis.It is indispensable for the sexually reproductive organisms, any stage disruption of the process results in reproductive problem or even sertility. Although some key genes in spermtogenesis has been identified by gene modification organisms, the complicated mechanism of it are still largely unkown. Abnormal spermatogenesis in human consequently lead to non obstructive azoospermia (NOA), including the severest form sertoli only syndrome(SCOS) which cannot be cured. In order to explore the mechanism of Spermatogenesis and the causing genes of SCOS resulted from abnormal spermatogenesis, three part work has been done:1.Meiosis is the basic feature of sexually reproductive organism, which is also the essential process of gamtogenesis. Until now, there are no proper in vitro system for meiosis imitation, most of the key genes involved in meiosis are from gene modified organisms; No system analysis of meiotic genes originated from various species has been done; Most of causing genes in NOA caused by abnormal meiosis has not been identified. Therefore, we collected all the paper related to meiosis in NCBI by querying the key words in meiosis, used manually curation and found2008genes reported to participate in spermatogenesis in80organisms from about40,000articles published before1May2013. We developed a database, MeiosisOnline1.0, is the first integrative resource to include the identified and predicted meioticgenes, and related scientific information.606genes are predicted to participate in the regulation of meiosis by our previousGAS (Greed AUC Stepwise) model (Probability>0.5). Annotation of the identified and predicted meiotic genes, which include protein function and cellular location, related literature, Gene Ontology (GO), and protein-protein interaction (PPI) information were performed.2. In order to explore the possible gene involved in spermatogenesis, we chosen the gene Pdia3as a candidate for the germ cell and sertoli cell location and early embryo lethality for knockout mice. Deletion the gene in germ cells by cre-loxp system resulted in comprising sperm fertilization capability and retarding the development of preimplantation embryo which fertilized by Pdia3defective sperm. However, deletion the gene in sertoli cells did not have discernible effect on spermatogenesis and fertility. The result suggests the important role of Pdia3in sperm fertilization capability and preimplantation embryo development.3. It is estimated that more than2330genes are involved in male gametogenesis, and about400are validated by knockout mice during male gametogenesis, NOA causing genes are still largely unknown. To explore the possible causing genes in SCOS cases, more than2000NOA cases were collected and classified by testicular sections and spermatocyte microspread for spermatogenesis and meiotic prophase investigation resepectively. SCOS cases were selected after precluding the secondary factors caused cases by PME(Physical, Medical and Exposure information). Blood DNA from20SCOS cases were used for the whole exome sequencing, the WES data were analyzed by bioinformatic method and reports published, two candidate genes HELQ and BRD4were chosen. In order to check whether the possible causing genes has the role in SCOS, for HELQ, encoding a DNA helicase, a variant T490A was found in1out of20cases undergone WES analysis and was confirmed by the Sanger sequencing. This mutation was also detected in1out of168unrelated SCOS cases by Sanger sequencing of all the18exons of Helq,4novel mutations in HELQ were also detected. Interestingly, knockout mice of this gene have been demonstrated to develop SCOS. The mutations of HELQ account for4.37%of the total SCOS. For BRD4,2missense mutations in20cases as well as3novel missense mutations in166cases was found by WES and Sanger sequencing respectively. The mutations of BRD4occupy4.30%of the total SCOS. Knockdown the drosophila gene fs(1)h, the ortholog of human BRD4, in GSC by UAS-GAL4system, resulted in completely germ cell loss, a similar phenotype of human SCOS. We firstly identified the SCOS causing genes, and found it had a role in GSC. Novel genes and molecular mechanisms underlying SCOS will be revealed by this systemic study and can be used as diagnostic and genetic screening biomarkers for SCOS patients.