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

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。VIA磷脂酶A2 （iPLA2B）是第一个被确认的细胞质Ca2+独立的PLA2，已被提出参与花生四烯酸（20:4）结合到甘油磷胆碱脂质，细胞增殖，胞吐，凋亡等过程。为了研究iPLA2B的功能，我们通过同源重组破坏其基因，产生不表达iPLA2B的小鼠。杂合iPLA2B+/-繁殖对产生的iPLA2B+/+、iPLA2B+/-和iPLA2B-/-幼崽的孟德尔比例为1:2:1，iPLA2B-/-幼崽的雌雄比例为1:1。野生型小鼠的几种组织表达iPLA2B mRNA、免疫反应蛋白和活性，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-/-小鼠的睾丸不缺乏含20:4的甘油酰胆碱脂质，这表明iPLA2B在该组织中不具有强制性的脂质形成作用。iPLA2B/-小鼠的精子在体外和体内运动能力下降，与小鼠卵母细胞受精的能力受损，用溴烯醇内酯自杀底物抑制iPLA2B使野生型精子的运动能力呈时间和浓度依赖性。iPLA2B-/-雄性小鼠与iPLA2B+/+、iPLA2B+/-或iPLA2B-/-雌性小鼠交配的产仔量仅为与iPLA2B+/+或iPLA2B+/-雄性小鼠交配的产仔量的7%左右，但iPLA2B-/-雌性小鼠的生育能力几乎正常。这些发现表明，iPLA2B在精子中发挥着重要的功能作用，为开发男性避孕药提供了靶点，并补充了IVA组PLA2 （cPLA2B）基因的破坏会损害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.