Human endometrial epithelium (EE) is composed of a multitude of proteins, amongst which those localized on the plasma membrane [plasma membrane proteins (PMPs)] are of critical relevance in the early stages of implantation. Evidence supports the key role of few PMPs in implantation. However, many remain unidentified, as efforts have not been made till date to generate the plasma membrane proteome of human EE cells, using a gel-free approach. This study presents a protein catalog of the PMP enriched fraction of Ishikawa cell line; often used as an in vitro model for embryo-adhesive EE. Liquid chromatography with tandem mass spectrometry identified 3,598 proteins. Of these, 1,963 proteins were annotated for their membrane localization. Of 1,963 proteins, 1,321 were found to have a transmembrane domain and 43 proteins had glycophosphatidylinositol (GPI) anchor. Extensive data mining revealed endometrial expression of 943 proteins reported in humans and/or rodents. Further, quantitative alterations were observed in the plasma membrane proteome on the perturbation of intracellular trafficking. Silencing of Rab11a (known for its role in plasma membrane organization) expression caused alteration in the abundance of 74 proteins. Caveolin-1 and EpCAM levels were reduced whereas Rab4a abundance increased in the PMP extracts of Rab11a deficient cells, compared with control cells. Briefly, the study reports the identity of several novel plasma membrane-localized proteins. A major spin-off of the study is the identification of novel proteins trafficked by Rab11a to the plasma membrane. Targeted analysis of novel PMPs may reveal their specific roles in endometrial receptivity and implantation.

中文翻译：

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具有黏附能力的子宫内膜上皮细胞的质膜蛋白质组及其受Rab11a调控。

人子宫内膜上皮（EE）由多种蛋白质组成，其中位于质膜上的那些蛋白质[质膜蛋白（PMP）]在植入的早期阶段具有至关重要的意义。证据支持少数PMP在植入中的关键作用。然而，许多人仍然不明，因为迄今为止尚未进行使用无胶方法产生人EE细胞质膜蛋白质组的努力。该研究提供了石川细胞系中富含PMP的蛋白目录。通常用作胚胎粘附EE的体外模型。液相色谱-串联质谱鉴定出3,598种蛋白质。其中，对1,963种蛋白质的膜定位进行了注释。在1,963种蛋白质中，1种 发现321个蛋白具有跨膜结构域，而43个蛋白具有糖磷脂酰肌醇（GPI）锚。广泛的数据挖掘揭示了人类和/或啮齿动物中报道的943种蛋白质的子宫内膜表达。此外，在细胞内运输的扰动下，在质膜蛋白质组中观察到定量改变。Rab11a的沉默（以其在质膜组织中的作用而闻名）的表达引起74种蛋白质丰度的改变。与对照细胞相比，在Rab11a缺陷细胞的PMP提取物中，Caveolin-1和EpCAM水平降低，而Rab4a丰度增加。简而言之，该研究报告了几种新型质膜定位蛋白的身份。该研究的主要衍生产品是鉴定Rab11a转运至质膜的新型蛋白质。