Zhang Shangrong, Liu Qing, Wang Siyu, Zhang Xiaoyu, Qin Dingmei, Bai Ruisong, Chen Ji, Ma Zijian, Lin Zhipeng, Bi Yuheng, Liu Huan, Sun Aoxue, Mo Zhongzhi, Wang Hongcheng, Wu Xiaoqing, Liu Yong
Anhui Province Key Laboratory of Embryo Development and Reproductive Regulation, Fuyang Normal University, Fuyang, Anhui, China.
FASEB J. 2025 Jun 15;39(11):e70723. doi: 10.1096/fj.202500640R.
Thioredoxin (TRX)-related transmembrane proteins (TMX), a subgroup of the protein disulfide isomerase (PDI) family, comprise a class of transmembrane proteins with diverse biological functions. Among these, TMX2 (PDIA12) remains one of the least characterized members. Recent studies have identified missense mutations in TMX2 associated with aberrant brain development and cerebellar malformations, highlighting its potential importance in developmental processes. Notably, Tmx2 mutant embryos exhibit developmental arrest at the E3.5 stage, suggesting a critical role in preimplantation embryogenesis. However, the precise molecular and cellular functions of Tmx2 in mammalian embryonic development remain largely unexplored. In this study, we provide novel insights into the essential role of Tmx2 during preimplantation embryonic development in mice. We demonstrate that TMX2 is specifically expressed in mouse embryos, with its subcellular localization closely associated with mitochondria during the two-cell to eight-cell stages. Knockdown of Tmx2 recapitulates the phenotypic defects observed in genetic mutants, revealing a pronounced impairment in blastomere proliferation, as confirmed by EdU incorporation assays. Furthermore, TUNEL assays indicate a significant increase in apoptotic signaling in Tmx2-deficient embryos, accompanied by elevated mRNA levels of the cell cycle inhibitors p21 and p53. Mechanistically, we show that Tmx2 knockdown disrupts mitochondrial function, leading to oxidative stress and impaired mitophagy and autophagy in developing embryos. These findings suggest that Tmx2 plays a pivotal role in maintaining mitochondrial integrity and cellular homeostasis during preimplantation embryogenesis. In summary, our study elucidates the critical role of Tmx2 in preimplantation embryonic development in mice, primarily through its regulation of mitochondrial function. These results advance our understanding of the molecular mechanisms governing preimplantation embryonic development and establish Tmx2 as a key regulator of mitochondrial dynamics and cellular survival during this critical developmental window.
硫氧还蛋白（TRX）相关跨膜蛋白（TMX）是蛋白质二硫键异构酶（PDI）家族的一个亚组，由一类具有多种生物学功能的跨膜蛋白组成。其中，TMX2（PDIA12）仍是特征描述最少的成员之一。最近的研究发现TMX2中的错义突变与异常脑发育和小脑畸形有关，突出了其在发育过程中的潜在重要性。值得注意的是，Tmx2突变胚胎在E3.5阶段出现发育停滞，表明其在植入前胚胎发生中起关键作用。然而，Tmx2在哺乳动物胚胎发育中的确切分子和细胞功能仍 largely未被探索。在本研究中，我们对Tmx2在小鼠植入前胚胎发育中的重要作用提供了新的见解。我们证明TMX2在小鼠胚胎中特异性表达，在二细胞至八细胞阶段其亚细胞定位与线粒体密切相关。Tmx2的敲低重现了在基因缺陷小鼠中观察到的表型缺陷，通过EdU掺入试验证实，卵裂球增殖明显受损。此外，TUNEL试验表明Tmx2缺陷胚胎中的凋亡信号显著增加，同时细胞周期抑制剂p21和p53的mRNA水平升高。从机制上讲，我们表明Tmx2敲低会破坏线粒体功能，导致发育中的胚胎出现氧化应激以及线粒体自噬和自噬受损。这些发现表明Tmx2在植入前胚胎发生过程中在维持线粒体完整性和细胞内稳态方面起关键作用。总之，我们的研究阐明了Tmx2在小鼠植入前胚胎发育中的关键作用，主要是通过其对线粒体功能的调节。这些结果推进了我们对植入前胚胎发育调控分子机制的理解，并确立了Tmx2作为这一关键发育窗口期间线粒体动力学和细胞存活的关键调节因子。
