Sequestering of cholesterol (CHO) is a hallmark molecular event that is known to be associated with sperm gaining their fertilizing ability in a broad array of animals. We have shown previously that the level of CHO declines in the Macrobrachium rosenbergii sperm membrane when they are migrating into the vas deferens, prompting us to search for CHO transporters, one of which is Niemann–Pick type 2C (NPC2), within the prawn male reproductive tract. Sequence comparison of MrNPC2 with other NPC2, from crustaceans to mammals, revealed its conserved features in the hydrophobic cavity with 3 amino acids forming a CHO lid that is identical in all species analyzed. Expressions of MrNPC2 transcript and protein were detected in testicular supporting and interstitial cells and along the epithelial cells of the vas deferens. As confirmed by live cell staining, the testicular sperm (Tsp) surface was devoid of MrNPC2 but it first existed on the vas deferens sperm, suggesting its acquisition from the luminal fluid, possibly through trafficking of multi-lamellar vesicles during sperm transit in the vas deferens. We further showed that recombinant MrNPC2 had a high affinity towards CHO in the lipid extracts, either from Tsp or from lipid vesicles in the vas deferens. Together, our results indicated the presence of MrNPC2 in the male reproductive tract, which may play an important role as a CHO modulator between the sperm membrane and vas deferens epithelial communication.

中文翻译：

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Niemann-Pick 2C 型（NPC2）在对虾生殖道中的存在和分布及其在输精管精子转运过程中作为胆固醇调节剂的假定作用

胆固醇螯合 (CHO) 是一种标志性的分子事件，众所周知，它与精子在多种动物中获得受精能力有关。我们之前已经表明，当罗氏沼虾迁移到输精管时，罗氏沼虾精子膜中的 CHO 水平下降，这促使我们在对虾雄性体内寻找 CHO 转运蛋白，其中之一是 Niemann-Pick 2C 型（NPC2）生殖道。从甲壳类动物到哺乳动物，MrNPC2 与其他 NPC2 的序列比较揭示了其在疏水腔中的保守特征，其中 3 个氨基酸形成了在所有分析的物种中都相同的 CHO 盖。在睾丸支持细胞和间质细胞以及沿着输精管的上皮细胞中检测到 MrNPC2 转录物和蛋白质的表达。经活细胞染色证实，睾丸精子 (Tsp) 表面没有 MrNPC2，但它首先存在于输精管精子上，这表明它从管腔液中获取，可能是通过在精子在输精管中运输过程中运输多层囊泡。我们进一步表明重组 MrNPC2 对脂质提取物中的 CHO 具有高亲和力，无论是来自 Tsp 还是来自输精管中的脂质囊泡。总之，我们的结果表明，在男性生殖道中存在 MrNPC2，它可能作为 CHO 调节剂在精子膜和输精管上皮通讯之间发挥重要作用。可能是通过在输精管中的精子运输过程中运输多层囊泡。我们进一步表明重组 MrNPC2 对脂质提取物中的 CHO 具有高亲和力，无论是来自 Tsp 还是来自输精管中的脂质囊泡。总之，我们的结果表明，在男性生殖道中存在 MrNPC2，它可能作为 CHO 调节剂在精子膜和输精管上皮通讯之间发挥重要作用。可能是通过在输精管中的精子运输过程中运输多层囊泡。我们进一步表明重组 MrNPC2 对脂质提取物中的 CHO 具有高亲和力，无论是来自 Tsp 还是来自输精管中的脂质囊泡。总之，我们的结果表明，在男性生殖道中存在 MrNPC2，它可能作为 CHO 调节剂在精子膜和输精管上皮通讯之间发挥重要作用。