Hexafluoropropylene oxide homologues, the novel alternatives to PFOA, induce mitochondrial dysfunction and cytotoxicity in Leydig cells through disrupting SIRT1/PGC-1α signaling pathway

Hexafluoropropylene oxide (HFPO) homologues (HFPOs), specifically HFPO-dimeric acid (DA), HFPO-trimeric acid (TA) and HFPO-tetrameric acid (TeA), have emerged as industrial replacements for phased-out perfluorooctanoic acid (PFOA), garnering considerable attention due to their environmental ubiquity and bioaccumulation potential. Nevertheless, the reproductive toxicity of HFPOs remains incompletely characterized, particularly regarding their endocrine-disrupting effect and the underlying mechanisms involving Leydig cell dysfunction. In this study, we investigated the cytotoxic influences of HFPOs on TM3 Leydig cells, focusing on mitochondrial function and dynamics, oxidative stress, and apoptosis. Our findings demonstrated that exposure to HFPOs significantly compromised mitochondrial function and fusion-fission dynamics by disrupting the SIRT1/PGC1α signaling pathway. The mitochondrial dysfunction further triggered excessive ROS production and apoptosis, ultimately impairing TM3 Leydig cell viability and testosterone secretion. However, supplementation with the SIRT1 agonist SRT1720 relieved the inhibitory effect of HFPOs on SIRT1/PGC1α signaling pathway and reversed the expression of apoptosis-associated proteins (BAX/BCL2), oxidative stress-associated proteins (SOD1/SOD2), as well as proteins associated with mitochondrial fusion (MFN2/OPA1) and fission (DRP1/FIS1). These results elucidated the involvement of the SIRT1/PGC1α pathway in mediating the cytotoxicity of HFPOs. Notably, the activation of SIRT1 mitigated HFPO-induced toxicity in the TM3 cells, highlighting its potential in safeguarding testicular cells from the damage caused by HFPOs exposure.