A novel role of tRNA-derived fragments in porcine granulosa-oocyte cell communication and cuproptosis

Copper is essential for reproductive function, yet its accumulation can lead to cytotoxicity and cuproptosis. However, the specific molecular mechanisms underlying granulosa cell cuproptosis and follicular atresia remain unclear. Particularly, the molecular pathway by which tRNA-derived fragments (tRFs), recognized as crucial epigenetic regulators, are involved in the regulation of granulosa cell cuproptosis requires further elucidation. In this study, we indicated that copper accumulation disrupted mitochondrial respiration and protein lipoylation, resulting in impaired mitochondrial TCA cycling and subsequent cellular metabolic imbalance. Furthermore, a direct correlation was identified between tRFs and copper homeostasis. Functional analysis demonstrated that tRF-Gly-M3, produced by angiopoietin (ANG) splicing, was significantly upregulated in granulosa cells cuproptosis, and impaired mitochondrial function to induce cuproptosis by silencing the expression of GLS mRNA. tRF-Gly-M3 in exosomes secreted by cuproptosis-induced granulosa cells was high expression, and these exosomes could be delivered into oocytes. tRF-Gly-M3 also impaired oocytes mitochondrial metabolic function, inhibited oocytes maturation, first polar body extrusion and parthenogenesis via silencing GLS mRNA. Overall, our findings indicated that tRFs from granulosa cells could be intercellularly delivered to oocytes, effectively regulating oocyte development.