GROUP VIA PHOSPHOLIPASE A2 AND SPERM WITH IMPAIRED MOTILITY/REDUCED FERTILITY

这个子项目是利用由NIH/NCRR资助的中心拨款提供的资源的许多研究子项目之一。子项目和调查员(PI)可能从另一个NIH来源获得了主要资金，因此可能会出现在其他CRISE条目中。列出的机构是针对中心的，而不一定是针对调查员的机构。该组通过磷脂酶A2(IPLA2B)是第一个被发现的胞内钙非依赖性PLA2，并已被认为参与花生四烯酸(20：4)掺入甘油磷胆碱脂类，细胞增殖，胞吐，细胞凋亡等过程。为了研究iPLA2B的功能，我们通过同源重组破坏了它的基因，产生了不表达iPLA2B的小鼠。杂合的iPLA2B+/-繁殖对产生的iPLA2B+/+、iPLA2B+/-和iPLA2B-/-幼崽的孟德尔比例为1：2：1，iPLA2B-/-幼崽的雄性：雌性比例为1：1。野生型小鼠的多种组织表达iPLA2B基因、免疫活性蛋白和活性，其中睾丸表达水平最高。IPLA2B-/-小鼠的睾丸或其他组织不表达iPLA2B mRNA或蛋白，但iPLA2B-/-睾丸不缺乏含有20：4甘油磷胆碱的脂类，这表明iPLA2B在这些组织中不起到形成这种脂类的必备作用。来自iPLA2B/-小鼠的精子活力降低，在体外和体内受精小鼠卵母细胞的能力受损，用溴烯醇内酯自杀底物抑制iPLA2B以时间和浓度依赖的方式降低野生型精子的活力。IPLA2B-/-雄性小鼠与iPLA2B+/+、iPLA2B+/-或iPLA2B-/-雌性小鼠交配产生的幼鼠数量仅为与iPLA2B+/+或iPLA2B+/-雄性交配配对所产仔鼠数量的7%左右，但iPLA2B-/-雌性小鼠具有几乎正常的生育能力。这些发现表明iPLA2B在精子中起着重要的功能作用，为男性避孕药的开发提供了一个靶点，并补充了IVA PLA2组(CPLA2B)基因破坏女性生殖能力的报道。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The Group VIA Phospholipase A2 (iPLA2B) is the first recognized cytosolic Ca2+-independent PLA2 and has been proposed to participate in arachidonic acid (20:4) incorporation into glycerophosphocholine lipids, cell proliferation, exocytosis, apoptosis, and other processes. To study iPLA2B functions, we disrupted its gene by homologous recombination to generate mice that do not express iPLA2B. Heterozygous iPLA2B+/- breeding pairs yield a Mendelian 1:2:1 ratio of iPLA2B+/+, iPLA2B+/-, and iPLA2B-/- pups and a 1:1 male:female gender distribution of iPLA2B-/- pups. Several tissues of wild-type mice express iPLA2B mRNA, immunoreactive protein, and activity, and testes express the highest levels. Testes or other tissues of iPLA2B-/- mice express no iPLA2B mRNA or protein, but iPLA2B-/- testes are not deficient in 20:4-containing glycerophosphocholine lipids, indicating that iPLA2B does not play an obligatory role in formation of such lipids in that tissue. Spermatozoa from iPLA2B/- mice have reduced motility and impaired ability to fertilize mouse oocytes in vitro and in vivo, and inhibiting iPLA2B with a bromoenol lactone suicide substrate reduces motility of wild-type spermatozoa in a time- and concentration-dependent manner. Mating iPLA2B-/- male mice with iPLA2B+/+, iPLA2B+/-, or iPLA2B-/- female mice yields only about 7% of the number of pups produced by mating pairs with an iPLA2B+/+ or iPLA2B+/- male, but iPLA2B-/- female mice have nearly normal fertility. These findings indicate that iPLA2B plays an important functional role in spermatozoa, suggest a target for developing male contraceptive drugs, and complement reports that disruption of the Group IVA PLA2 (cPLA2B) gene impairs female reproductive ability.