Fang Qian, Liu Biyun, Cen Jie, Li Tongtong, Ji Shuhui, Li Wenqing, Lu Gang, Chen Zi-Jiang, Wang Xin, Bao Jianqiang, Liu Hongbin
Institute of Women, Children and Reproductive Health, Shandong University, Jinan, 250012, China.
State Key Laboratory of Reproductive Medicine and Offspring Health, Shandong University, Jinan, Shandong, 250012, China.
Commun Biol. 2025 Jul 28;8(1):1114. doi: 10.1038/s42003-025-08539-1.
Protein dephosphorylation mediated by phosphatases regulates spermatogenesis. However, which proteins are dephosphorylated and how they regulate spermatogenesis are largely unknown. Here, we show that germline-specific deletion of protein phosphatase 6 regulatory subunit 3 (PPP6R3), which determines substrate specificity of protein phosphatase 6 (PP6), causes abnormal spermatogonial differentiation and male infertility, accompanied by translation inhibition. PPP6R3 directly interacts with EIF3C and EIF4G1 in KIT spermatogonia. Decreased levels of non-phosphorylated EIF3C and EIF4G1 after PPP6R3 deletion attenuate their enrichment for mRNAs associated with spermatogonial differentiation, and increased phosphorylation levels promote their degradation. Specifically, the phosphorylation status both of EIF3C and EIF4G1 are significantly up-regulated in mutant mice. Overexpression of EIF3C and EIF4G1 mutants in Ppp6r3-cKO spermatogonial progenitor cells compensates for the deficiency of differentiation potential by upregulating translation rates of differentiation-associated mRNAs. Our findings demonstrate EIF3C and EIF4G1, as specific substrates of PPP6R3/PP6 holoenzyme, are required for translation activation during spermatogonial differentiation.
由磷酸酶介导的蛋白质去磷酸化调节精子发生。然而，哪些蛋白质会发生去磷酸化以及它们如何调节精子发生在很大程度上尚不清楚。在这里，我们表明，生殖系特异性缺失决定蛋白磷酸酶6（PP6）底物特异性的蛋白磷酸酶6调节亚基3（PPP6R3）会导致精原细胞分化异常和雄性不育，并伴有翻译抑制。PPP6R3在KIT精原细胞中直接与EIF3C和EIF4G1相互作用。PPP6R3缺失后，非磷酸化EIF3C和EIF4G1水平降低，减弱了它们对与精原细胞分化相关mRNA的富集，而磷酸化水平升高则促进其降解。具体而言，在突变小鼠中，EIF3C和EIF4G1的磷酸化状态均显著上调。在Ppp6r3-cKO精原细胞祖细胞中过表达EIF3C和EIF4G1突变体，通过上调分化相关mRNA的翻译速率来弥补分化潜能的不足。我们的研究结果表明，EIF3C和EIF4G1作为PPP6R3/PP6全酶的特异性底物，是精原细胞分化过程中翻译激活所必需的。
