Li Huanhuan, Li Yuejia, Liu Junsheng, Liu Xuan, Li Yuanjing, Wang Shusong, Ma Jing
Hebei Key Laboratory of Reproductive Medicine, Hebei Reproductive Health Hospital, No. 480 Heping Street, Shijiazhuang, 050071, Xinhua District, Hebei, China.
Graduate School of Hebei Medical University, Shijiazhuang, 050017, China.
In Vitro Cell Dev Biol Anim. 2023 Sep;59(8):565-574. doi: 10.1007/s11626-023-00804-z. Epub 2023 Sep 21.
Zinc deficiency has a huge impact on male reproduction. The zinc transporter (ZnT) family is involved in the maintenance of zinc homeostasis and testosterone synthesis. However, the underlying mechanisms remain to be investigated. Therefore, in this study, we aimed to determine the effect of zinc transporter 4 (ZnT4) on testosterone synthesis in male Kunming mice and mouse Leydig cells. The results of this study showed that compared with the zinc normal diet group (Con group), the zinc-deficient diet group (ZnD group) had decreased zinc content and increased ZnT4 expression in testicular tissues, and decreased serum testosterone levels, suggesting that ZnT4 may be involved in Leydig cell injury resulting from a zinc-deficient diet. Subsequently, mouse Leydig cell line TM3 cells were used to analyze the effect of ZnT4 downregulation on TM3 cell proliferation and apoptosis, on testosterone synthesis, and its underlying mechanisms. Here, we show that knockdown of ZnT4 can induce the accumulation of zinc, inhibit the viability, and induce apoptosis in TM3 cells. In addition, knockdown of ZnT4 downregulated testosterone concentration and expression of testosterone synthesis-related proteins steroidogenic acute regulatory protein (StAR) and 3β-hydroxysteroid dehydrogenase/D5-D4 isomerase (3β-HSD) in TM3 cells, while hCG could rescue their levels. We show that it is ZnT4 that plays a role in testosterone production through a mediated PI3K/Akt/mTOR autophagy pathway, whereas mTORC1 complex inhibitor (Rapa) blocks the decrease in testosterone levels caused by ZnT4 downregulation. In conclusion, the above results indicate that ZnT4 plays an important role in regulating testosterone synthesis.
锌缺乏对雄性生殖有巨大影响。锌转运蛋白（ZnT）家族参与锌稳态的维持和睾酮合成。然而，其潜在机制仍有待研究。因此，在本研究中，我们旨在确定锌转运蛋白4（ZnT4）对雄性昆明小鼠和小鼠睾丸间质细胞睾酮合成的影响。本研究结果表明，与正常锌饮食组（Con组）相比，缺锌饮食组（ZnD组）睾丸组织中的锌含量降低，ZnT4表达增加，血清睾酮水平降低，这表明ZnT4可能参与了缺锌饮食导致的睾丸间质细胞损伤。随后，使用小鼠睾丸间质细胞系TM3细胞分析ZnT4下调对TM3细胞增殖、凋亡、睾酮合成及其潜在机制的影响。在此，我们表明敲低ZnT4可诱导锌积累，抑制TM3细胞活力并诱导其凋亡。此外，敲低ZnT4可下调TM3细胞中睾酮浓度以及睾酮合成相关蛋白类固醇生成急性调节蛋白（StAR）和3β-羟基类固醇脱氢酶/D5-D4异构酶（3β-HSD）的表达，而人绒毛膜促性腺激素（hCG）可使其水平恢复。我们表明，ZnT4通过介导PI3K/Akt/mTOR自噬途径在睾酮生成中发挥作用，而mTORC1复合物抑制剂（雷帕霉素）可阻断ZnT4下调引起的睾酮水平降低。总之，上述结果表明ZnT4在调节睾酮合成中起重要作用。
