Freour T, Barragan M, Ferrer-Vaquer A, Rodríguez A, Vassena Rita
Clínica Eugin, Traversera de les Corts, 322 - 08029, Barcelona, Spain.
Service de médecine de la reproduction, CHU de Nantes, 44093, Nantes, France.
J Assist Reprod Genet. 2017 Jun;34(6):803-810. doi: 10.1007/s10815-017-0902-x. Epub 2017 Mar 21.
WBP2NL/PAWP, a protein found in the post-acrosomal region of mammalian spermatozoa, has been proposed as a sperm-borne oocyte-activating factor (SOAF) contributing to Ca release within the oocyte and subsequent fertilization and embryo development. However, its relevance as either a diagnostic or a prognostic marker of fertilization failure has been questioned in the recent literature. We analyzed WBP2NL/PAWP gene and protein expression level and localization in patients without previous intracytoplasmic sperm injection (ICSI) cycles in order to assess its association with both sperm characteristics and ability to fertilize.
Raw frozen-thawed semen samples from 33 couples referred for oocyte donation were included in the study during 2015. Relative protein expression versus α-tubulin (western blot, WB), proportion of post-acrosomal WBP2NL/PAWP-positive spermatozoa over the total number of sperm cells (immunofluorescence), and WBP2NL/PAWP gene expression (RT-qPCR) were analyzed and correlated with semen analysis parameters (number, motility, and morphology) and with reproductive outcomes.
WBP2NL/PAWP protein was expressed in all samples with high variability: relative protein expression (1.77 ± 0.8, range [0.4-3.7]), proportion of positive cells (49.6% ± 16.1, range [22-89]), and relative gene expression (7.3 ± 8.2). No significant correlation (R < 0.1) was found between gene and protein expression, neither between WBP2NL/PAWP gene or protein expression, and fertilization rate or other reproductive outcomes (i.e., pregnancy). In contrast, we found significant correlation between sperm morphology and WBP2NL/PAWP semiquantitative analysis in WB (r = -0.42, p < 0.05) and for sperm motility and WBP2NL/PAWP expression in IF (r = 0.52, p < 0.05).
Taken into account that WBP2NL/PAWP gene and protein levels and distribution did not correlate with fertilization rates, this study questions the interest of WBP2NL/PAWP protein and gene expression analysis in sperm cells as a prognostic factor for the outcome of ICSI cycles. Larger studies focusing on WBP2NL/PAWP protein and gene expression are needed in order to evaluate the role of WBP2NL/PAWP as a prognostic factor for ART.
WBP2NL/PAWP是一种在哺乳动物精子顶体后区域发现的蛋白质，被认为是一种精子携带的卵母细胞激活因子（SOAF），有助于卵母细胞内的钙释放以及随后的受精和胚胎发育。然而，近期文献对其作为受精失败的诊断或预后标志物的相关性提出了质疑。我们分析了未进行过卵胞浆内单精子注射（ICSI）周期的患者中WBP2NL/PAWP基因和蛋白的表达水平及定位，以评估其与精子特征和受精能力的关联。
2015年，研究纳入了33对因卵子捐赠前来就诊的夫妇的冷冻解冻精液原始样本。分析了相对于α-微管蛋白的相对蛋白表达（蛋白质印迹法，WB）、顶体后WBP2NL/PAWP阳性精子在精子细胞总数中的比例（免疫荧光法）以及WBP2NL/PAWP基因表达（逆转录定量聚合酶链反应，RT-qPCR），并将其与精液分析参数（数量、活力和形态）以及生殖结局进行关联分析。
所有样本中均表达WBP2NL/PAWP蛋白，且变异性较高：相对蛋白表达（1.77±0.8，范围[0.4 - 3.7]）、阳性细胞比例（49.6%±16.1，范围[22 - 89]）以及相对基因表达（7.3±8.2）。基因与蛋白表达之间、WBP2NL/PAWP基因或蛋白表达与受精率或其他生殖结局（即妊娠）之间均未发现显著相关性（R < 0.1）。相反，我们发现精子形态与WB中WBP2NL/PAWP的半定量分析之间存在显著相关性（r = -0.42，p < 0.05），精子活力与IF中WBP2NL/PAWP表达之间存在显著相关性（r = 0.52，p < 0.05）。
鉴于WBP2NL/PAWP基因和蛋白水平及分布与受精率无关，本研究对精子细胞中WBP2NL/PAWP蛋白和基因表达分析作为ICSI周期结局的预后因素的意义提出了质疑。需要开展更多聚焦于WBP2NL/PAWP蛋白和基因表达的研究，以评估WBP2NL/PAWP作为辅助生殖技术预后因素的作用。
