Key Lab of Medical Protection for Electromagnetic Radiation, Ministry of Education of China, Institute of Toxicology, College of Preventive Medicine, Third Military Medical University, Chongqing 400038, China.
State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Biotechnology, Beijing, China.
Toxicol Appl Pharmacol. 2023 Sep 15;475:116656. doi: 10.1016/j.taap.2023.116656. Epub 2023 Aug 12.
Telomere and mitochondria may be the targets of Benzo[a]pyrene (BaP) -induced male reproductive damage, and further elucidation of the toxic molecular mechanisms is necessary. In this study, we used in vivo and in vitro exposure models to explore the molecular mechanisms of TERT regulation in BaP-induced telomere and mitochondrial damage in spermatocytes. The results showed that the treatment of benzo[a]pyrene-7,8-dihydrodiol-9,10-epoxide (BPDE), the active metabolite of BaP, caused telomere dysfunction in mouse spermatocyte-derived GC-2 cells, resulting in S-phase arrest and increased senescence-associated secretory phenotype (SASP). These effects were significantly alleviated by telomerase agonist (ABG) pretreatment in GC-2 cells. SIRT1, FOXO3a, or c-MYC overexpressing GC-2 cell models were established to demonstrate that BPDE inhibited TERT transcriptional expression through the SIRT1/FOXO3a/c-MYC pathway, leading to telomere dysfunction. We also observed that BPDE induced mitochondrial compromise, including complex I damage, accompanied by reduced mitochondrial TERT expression. Based on this, we constructed wild-type TERT-overexpressing (OE-TERT) and mitochondria targeting TERT-overexpressing (OE-TERT) GC-2 cell models and found that OE-TERT GC-2 cells improved mitochondrial function better than OE-TERT GC-2 cells. Finally, ICR mice were given BaP by intragastric administration for 35 days, which verified the results of the in vitro study. The results shown that BaP exposure can lead to spermatogenesis disturbance, which is related to the telomere and mitochondrial damage in spermatocytes. In conclusion, our results suggest that BPDE causes telomere and mitochondrial damage in spermatocytes by inhibiting TERT transcription and mitochondrial TERT expression. This study elucidates the molecular mechanism of male reproductive toxicity due to environmental pollutant BaP, and also provides a new perspective for the exploration of interventions and protective measures against male reproductive damage by BaP.
端粒和线粒体可能是苯并[a]芘（BaP）诱导雄性生殖损伤的靶点，需要进一步阐明其毒性的分子机制。在这项研究中，我们使用体内和体外暴露模型来探讨 BaP 诱导的精母细胞中端粒和线粒体损伤中 TERT 调节的分子机制。结果表明，苯并[a]芘-7,8-二氢二醇-9,10-环氧化物（BPDE），BaP 的活性代谢物，处理导致小鼠精母细胞源性 GC-2 细胞中端粒功能障碍，导致 S 期停滞和衰老相关分泌表型（SASP）增加。这些作用在 GC-2 细胞中用端粒酶激动剂（ABG）预处理可显著减轻。建立 SIRT1、FOXO3a 或 c-MYC 过表达 GC-2 细胞模型，证明 BPDE 通过 SIRT1/FOXO3a/c-MYC 通路抑制 TERT 转录表达，导致端粒功能障碍。我们还观察到 BPDE 诱导线粒体损伤，包括复合物 I 损伤，同时伴有线粒体 TERT 表达减少。基于此，我们构建了野生型 TERT 过表达（OE-TERT）和线粒体靶向 TERT 过表达（OE-TERT）GC-2 细胞模型，发现 OE-TERT GC-2 细胞比 OE-TERT GC-2 细胞更好地改善线粒体功能。最后，通过灌胃给予 ICR 小鼠 BaP 35 天，验证了体外研究结果。结果表明，BaP 暴露可导致精子发生紊乱，这与精母细胞中端粒和线粒体损伤有关。总之，我们的结果表明，BPDE 通过抑制 TERT 转录和线粒体 TERT 表达导致精母细胞中端粒和线粒体损伤。这项研究阐明了环境污染物 BaP 导致雄性生殖毒性的分子机制，也为探索 BaP 引起的雄性生殖损伤的干预和保护措施提供了新的视角。
