Department of Anatomy and Embryology, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime, 791-0212, Japan.
Medical Education Center, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime, Japan.
Cell Tissue Res. 2021 Mar;383(3):1191-1202. doi: 10.1007/s00441-020-03339-x. Epub 2020 Nov 26.
Prosaposin (PSAP) has two forms: a precursor and a secreted form. The secreted form has neurotrophic, myelinotrophic, and myotrophic properties. The precursor form is a precursor protein of saposins A-D. Although the distribution of PSAP in male reproductive organs is well known, its distribution in female reproductive organs, especially in the oviduct, is unclear. Immunoblots and immunohistochemistry of oviducts showed that oviductal tissues contain PSAP proteins, and a significant increase in PSAP was observed in the estrus-metestrus phase compared to the diestrus-proestrus phase in the ampulla. To identify PSAP trafficking in cells, double-immunostaining was performed with antibodies against PSAP in combination with sortilin, mannose 6 phosphate receptor (M6PR), or low-density lipoprotein receptor-related protein 1 (LRP1). PSAP and sortilin double-positive reactions were observed near the nuclei, as well as in the apical portion of microvillous epithelial cells, whereas these reactions were only observed near the nuclei of ciliated epithelial cells. PSAP and M6PR double-positive reactions were observed near the nuclei of microvillous and ciliated epithelial cells. PSAP and M6PR double-positive reactions were also observed in the apical portion of microvillous epithelial cells. PSAP and LRP1 double-positive reactions were observed in the plasma membrane and apical portion of both microvillous and ciliated epithelial cells. Immunoelectron staining revealed PSAP immunoreactive small vesicles with exocytotic features at the apical portion of microvillous epithelial cells. These findings suggest that PSAP is present in the oviductal epithelium and has a pivotal role during pregnancy in providing an optimal environment for gametes and/or sperm in the ampulla.
前原蛋白 (PSAP) 有两种形式：前体和分泌型。分泌型具有神经营养、髓鞘营养和肌肉营养特性。前体形式是 saposins A-D 的前体蛋白。虽然 PSAP 在男性生殖器官中的分布众所周知，但它在女性生殖器官中的分布，特别是在输卵管中的分布尚不清楚。输卵管的免疫印迹和免疫组织化学显示，输卵管组织含有 PSAP 蛋白，与发情-间情期相比，PSAP 在壶腹部的发情-间情期明显增加。为了确定 PSAP 在细胞中的运输，用针对 PSAP 的抗体与分选蛋白、甘露糖 6 磷酸受体 (M6PR) 或低密度脂蛋白受体相关蛋白 1 (LRP1) 进行双重免疫染色。PSAP 和分选蛋白的双阳性反应在靠近细胞核的部位以及微绒毛上皮细胞的顶端部分观察到，而这些反应仅在纤毛上皮细胞的细胞核附近观察到。PSAP 和 M6PR 的双阳性反应在微绒毛和纤毛上皮细胞的细胞核附近观察到。PSAP 和 M6PR 的双阳性反应也在微绒毛上皮细胞的顶端部分观察到。PSAP 和 LRP1 的双阳性反应在微绒毛和纤毛上皮细胞的质膜和顶端部分观察到。免疫电镜染色显示 PSAP 免疫反应性小泡在微绒毛上皮细胞的顶端部分具有出胞特征。这些发现表明 PSAP 存在于输卵管上皮细胞中，在妊娠期间在壶腹部为配子和/或精子提供最佳环境方面发挥关键作用。
