Roles of seminolipid and its binding proteins in male reproduction

了解配子相互作用和配子形成的机制是提高家畜生育力的必要条件。 由于细胞粘附是精子-卵子相互作用和精子形成的主要机制之一，我们长期以来一直在这一领域进行研究。 我们专注于粘附分子，磺基半乳糖基甘油脂（SGG），发现选择性地在哺乳动物雄性生殖细胞，并已表明，精子表面SGG参与精卵vestment（透明带-ZP）的结合。 事实上，SGG与其结合蛋白芳基硫酸酯酶A（阿萨）一起作用于精子头部表面。 但由于SGG在精子上大量存在，因此可能有更多的SGG结合蛋白参与ZP结合。 我们将根据这些蛋白在体外与SGG膜结合的能力来分离它们，然后使用蛋白质组学方法来获得它们的身份。 同样，睾丸生殖细胞（TGC）表面上的SGG可能与支持细胞上的结合蛋白相互作用，支持细胞跨越整个睾丸小管层，精子由其干细胞产生。支持细胞对TGC进行细胞组织，使得更高级的TGC更靠近小管腔。 该支持细胞的功能可通过支持细胞上的TGC表面SGG和SGG结合蛋白之间的相互作用来协调。 因此，我们也想鉴定支持细胞表面的这些SGG结合蛋白。 我们进一步表明，存在于人类和啮齿动物附睾液中的两种进化上保守的抗菌肽（AMP）SPAG 11 D和SPAG 11 E与SGG结合，从而保护精子免受微生物的攻击。这些AMP的大量可用性将可用于各种动物的感染治疗。 我们最近的研究结果表明，SPAG 11 D存在于猪精浆中，因此，我们将纯化天然形式的SPAG 11 D，并测试其杀微生物活性。 我们的研究将深入了解SGG在男性生殖中的作用，这可能会导致提高畜牧业生产。

Understanding the mechanisms of gamete interaction and gamete formation is a requirement for fertility enhancement in livestock animals. Since cell adhesion is one main mechanism for both sperm-egg interaction and sperm formation in testes, our research efforts have long been invested in this area. We have focused on an adhesion molecule, sulfogalactosylglycerolipid (SGG), found selectively in mammalian male germ cells, and have shown that sperm surface SGG is involved in sperm-egg vestment (zona pellucida -ZP) binding. In fact, SGG acts together with its binding protein, arylsulfatase A (ASA), also on the sperm head surface. But since SGG exists in abundance on sperm, there would be more SGG binding proteins that participate in ZP binding. We will isolate these proteins based on their ability to bind to SGG membranes in vitro and then use a proteomics approach to obtain their identities. In the same vein, SGG on the testicular germ cell (TGC) surface may interact with its binding proteins on Sertoli cells, which span the whole testicular tubule layer, where sperm are produced from their stem cells. Sertoli cells cyto-organize TGCs, so that the more advanced TGCs are closer to the tubule lumen. This Sertoli cell's function may be orchestrated through the interaction between TGC surface SGG and SGG binding proteins on Sertoli cells. Therefore, we also want to identify these SGG binding proteins on the Sertoli cell surface. We have further shown that two evolutionarily conserved antimicrobial peptides (AMPs), SPAG11D and SPAG11E, present in human and rodent epididymal fluid, bind to SGG and thus protect sperm from microbial attacks. Availability of these AMPs in quantity will be useful for infection treatment in various animals. Our recent results reveal that SPAG11D is present in pig seminal plasma; we will therefore purify the native form SPAG11D and test for its microbicidal activity. Our study will bring insight to the roles of SGG in male reproduction, and this may lead to improved livestock production.