Key Laboratory of Environmental Toxicology of Anhui Higher Education Institutes, Anhui Medical University, Hefei 230032, China.
Key Laboratory of Environmental Toxicology of Anhui Higher Education Institutes, Anhui Medical University, Hefei 230032, China.
Environ Int. 2022 Sep;167:107393. doi: 10.1016/j.envint.2022.107393. Epub 2022 Jul 14.
In the past 50 years, testosterone (T) level in men has declined gradually. In this research, we discovered that acute exposure to 1-nitropyrene (1-NP), an environmental stressor from polluted atmosphere, reduced T contents by downregulating steroidogenic proteins in mouse testes and Leydig cells. Acute 1-NP exposure caused GCN2 activation and eIF2α phosphorylation, a marker of integrated stress, in mouse testes and Leydig cells. GCN2iB, a selective GCN2 kinase inhibitor, and siGCN2, the GCN2-targeted short interfering RNA, attenuated 1-NP-induced reduction of steroidogenic proteins in Leydig cells. Mechanistically, mitochondrial membrane potential was reduced and ATP5A, UQCRC2, SDHB and NDUFB8, four OXPHOS subunits, were reduced in 1-NP-exposed Leydig cells. Cellular mitochondrial respiration was inhibited and ATP production was reduced. Moreover, mitochondrial reactive oxygen species (ROS) were elevated in 1-NP-exposed Leydig cells. The interaction between GCN2 and uL10, a marker of ribosome stalling, was observed in 1-NP-exposed Leydig cells. MitoQ, a mitochondria-targeted antioxidant, attenuated1-NP-evoked ATP depletion and ribosome stalling in Leydig cells. Moreover, MitoQ suppressed 1-NP-caused GCN2 activation and eIF2α phosphorylation in Leydig cells. In addition, MitoQ alleviated 1-NP-induced steroidogenic inhibition in mouse testes. In conclusion, mitochondrial ROS-mediated ribosome stalling and GCN2 activation are partially involved in environmental stress-induced steroidogenic inhibition in testes.
在过去的 50 年中，男性的睾丸酮（T）水平逐渐下降。在这项研究中，我们发现，急性暴露于 1-硝基芘（1-NP），一种来自污染大气的环境应激物，通过下调睾丸和间质细胞中的类固醇生成蛋白来降低 T 含量。急性 1-NP 暴露导致 GCN2 激活和 eIF2α 磷酸化，这是整合应激的标志物，在小鼠睾丸和间质细胞中。GCN2iB，一种选择性 GCN2 激酶抑制剂，和 siGCN2，靶向 GCN2 的短干扰 RNA，减弱了 1-NP 诱导的间质细胞中类固醇生成蛋白的减少。机制上，线粒体膜电位降低，ATP5A、UQCRC2、SDHB 和 NDUFB8，四个 OXPHOS 亚基，在 1-NP 暴露的间质细胞中减少。细胞线粒体呼吸受到抑制，ATP 产生减少。此外，线粒体活性氧（ROS）在 1-NP 暴露的间质细胞中升高。在 1-NP 暴露的间质细胞中观察到 GCN2 和 uL10 之间的相互作用，uL10 是核糖体停滞的标志物。MitoQ，一种线粒体靶向抗氧化剂，减轻了 1-NP 引起的间质细胞中 ATP 耗竭和核糖体停滞。此外，MitoQ 抑制了 1-NP 引起的间质细胞中 GCN2 的激活和 eIF2α 的磷酸化。此外，MitoQ 减轻了 1-NP 引起的睾丸中类固醇生成抑制。总之，线粒体 ROS 介导的核糖体停滞和 GCN2 激活部分参与了环境应激引起的睾丸类固醇生成抑制。
