5-HMF是课题组近期从香烟烟雾中鉴定出的新的毒性组分，含量丰富，可被高度同源且功能相近的人CYP2A13和小鼠CYP2A5代谢活化，推测羟基化和呋喃环开环类结构为其主要的毒性代谢产物；CYP2A5和ATG12主要表达在小鼠精母细胞，敲除后均可明显缓解5-HMF所致的生精减少。提示CYP2A5可在精母细胞代谢活化5-HMF并通过ATG12介导的自噬影响精子发生，但未见报道。为此，本项目拟运用cyp2a5、atg12及联合敲除小鼠、原代精母细胞及GC-2细胞，采用针对5-HMF代谢产物结构设计合成的分子探针，评价CYP2A5介导的5-HMF在精母细胞中的原位代谢及生精障碍，分析ATG12介导的自噬通路在该损伤过程中的调控机制。试图阐明5-HMF作为香烟烟雾的主要组分在吸烟致男性精液质量下降中的重要作用，为男性生殖危害评估提供新的线索，也为丰富环境污染物的原位代谢和靶毒性提供理论与实践依据。

5-hydroxymethyl-2-furaldehyde (5-HMF) is a new abundant toxic component that was separated and identified from cigarette smoke by our research group, it was proved to be metabolically activated by human CYP2A13 and mouse CYP2A5, two cytochrome P450 enzymes with highly homologous and similar function. The main toxic metabolites were speculated as hydroxylation and furan ring opening form. In addition, we found that CYP2A5 and ATG12 were mainly expressed in primary spermatocytes, and the knockout of cyp2a5 or atg12 could significantly alleviate the spermatogenic cell reduction induced by 5-HMF, which suggested that 5-HMF could be metabolically activated by CYP2A5 in the spermatocyte and affect spermatogenesis through ATG12-mediated autophagy pathway. However, so far there is no related report about it. For this purpose, the present project intends to evaluate the in situ metabolism of 5-HMF by CYP2A5 in spermatocytes and related spermatogenesis disorder through the 5-HMF-treated cyp2a5-/- or atg12+/- or cyp2a5-/-atg12+/- mice, primary spermatocytes, GC-2 cells, and adopting molecular probes for 5-HMF metabolites. Still, the molecular mechanism of ATG12-mediated autophagy pathway in this spermatogenesis damage will be further analyzed. The study attempts to clarify the important role of 5-HMF as the main component in cigarette smoke in the smoking-induced decline of semen quality, provide new clues for preventing and controlling male reproductive hazards, and also to provide theoretical and practical basis for the study of the in situ metabolism of environmental pollutants in relation to the related target organ toxicity.