Abstract

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. Copper is vital for healthy reproduction, but excessive copper levels can poison cells, especially the critical granulosa cell in the ovary that support developing oocytes. Until now, the exact process of how this copper-induced stress causes cell death and impairs fertility has remained a mystery. We discovered that excess copper paralyzes the energy-producing centers of these granulosa cells, causing a massive energy failure. In response to this stress, we show that the cells increase production of tiny RNA fragments. These fragments dir