Loss ofPRICKLE1promotes abnormal endometrial epithelial architecture, reduced fertility, and decreased embryo implantation in mice.

Successful embryo implantation requires coordinated changes in the uterine luminal epithelium, including structural alterations, apical-basal polarity shifts, intrauterine fluid resorption, and cellular communication. These processes, collectively termed plasma membrane transformation (PMT), are crucial but poorly understood, especially regarding their regulation by planar cell polarity (PCP) proteins. PCP proteins, essential for cell organization, are understudied in the context of uterine physiology. Prickle proteins, particularly Prickle1, play critical roles in cellular polarization and tissue morphogenesis. However, their function in the endometrial epithelium during embryo implantation is unknown. To investigate Prickle1's role in uterine physiology, we developed an endometrial epithelial conditional knockout (cKO) of Prickle1 using Lactoferrin-icre. PRICKLE1 ablation in the endometrial epithelium resulted in decreased fertility and embryo implantation by gestational day 4.5. Three-dimensional imaging revealed abnormal luminal folding, impaired luminal closure, and altered glandular structure in mutant uteri. Additionally, we observed decreased aquaporin-2 expression, disrupted cellular architecture, and protein expression and localization in mutant uteri. Evidence of epithelial-to-mesenchymal transition (EMT) was found within luminal epithelial cells, further linking PRICKLE1 loss to uterine pathologies. Furthermore, altered cellular division planes and increased multinucleated cells suggested a connection to EMT. Our findings highlight PRICKLE1's critical role in the PCP pathway within the uterus, revealing its importance in the molecular and cellular responses essential for successful pregnancy establishment. Overall design: Whole uteri of Prickle1f/f Ltf-iCre cKO and control mice aged 6 months were isolated. Control samples (n=3) were pooled and cKO samples (n=3) were pooled.

成功的胚胎着床需要子宫腔上皮发生协同性变化，包括结构重塑、顶-基底极性转变、宫腔液体重吸收以及细胞通讯。上述过程被统称为血浆膜转化（plasma membrane transformation, PMT），虽至关重要却鲜有研究，尤其是关于其受平面细胞极性（planar cell polarity, PCP）蛋白调控的机制。平面细胞极性蛋白对细胞组织至关重要，但在子宫生理学领域的相关研究仍十分匮乏。Prickle蛋白家族（尤其是Prickle1）在细胞极化与组织形态发生中发挥关键作用，但其在胚胎着床过程中子宫内膜上皮内的功能尚未明确。为探究Prickle1在子宫生理学中的功能，我们利用乳铁蛋白-Cre（Lactoferrin-icre）构建了Prickle1子宫内膜上皮细胞条件性敲除（conditional knockout, cKO）小鼠模型。子宫内膜上皮中PRICKLE1的敲除会导致妊娠第4.5天时小鼠生育能力下降以及胚胎着床率降低。三维成像结果显示，敲除小鼠的子宫出现宫腔褶皱异常、宫腔闭合障碍以及腺体结构改变。此外，我们还观察到敲除小鼠子宫内水通道蛋白2（aquaporin-2）表达下调、细胞结构紊乱以及蛋白表达与定位异常。在腔上皮细胞中检测到上皮间质转化（epithelial-to-mesenchymal transition, EMT）的相关证据，进一步将PRICKLE1缺失与子宫病理变化联系起来。此外，细胞分裂平面改变以及多核细胞数量增加的现象，也提示其与上皮间质转化存在关联。本研究结果揭示了PRICKLE1在子宫内平面细胞极性通路中的关键作用，阐明了其对成功建立妊娠所必需的分子与细胞应答的重要性。实验整体设计：分离6月龄Prickle1f/f Ltf-iCre条件性敲除小鼠与对照小鼠的全子宫组织，将对照样本（n=3）混合，同时将条件性敲除样本（n=3）混合。