piRNA-46403 promotes Sertoli cell ferroptosis in varicocele-mediated infertility by acting as a molecular decoy that binds YBX1, disrupting m5C-dependent USP18 mRNA stabilization, and its silencing attenuates spermatogonial apoptosis and restores spermatogenic function.
Key Findings
Results
Sertoli cell ferroptosis is a critical pathological feature of varicocele (VC), and its pharmacological inhibition effectively rescues VC-induced reproductive impairment in vivo.
Ferroptosis was identified as a key pathological mechanism in VC-associated spermatogenic failure.
Pharmacological inhibition of ferroptosis was sufficient to rescue reproductive impairment in a VC animal model.
This establishes ferroptosis in Sertoli cells as a mechanistically important and therapeutically targetable process in VC.
Results
piRNA-46403 is significantly upregulated in testicular tissues of VC patients with asthenospermia.
Small RNA sequencing was performed on clinical testicular tissues from VC patients.
piRNA-46403 was identified as a significantly upregulated small RNA in VC patients with asthenospermia compared to controls.
The sequencing approach enabled identification of piRNA-46403 as a key mediator among the broader piRNA landscape in VC.
Results
piRNA-46403 orchestrates Sertoli cell ferroptosis, and its silencing attenuates spermatogonial apoptosis and restores spermatogenic function.
Functional studies demonstrated that piRNA-46403 promotes ferroptosis specifically in Sertoli cells.
Silencing of piRNA-46403 reduced spermatogonial apoptosis, indicating a paracrine or cell-cell interaction effect between Sertoli cells and spermatogonia.
Knockdown of piRNA-46403 was associated with restoration of spermatogenic function, supporting its role as a functional driver of VC-associated infertility.
Results
piRNA-46403 acts as a molecular decoy that binds to the RNA-binding protein YBX1, disrupting YBX1's interaction with m5C-modified USP18 mRNA.
Mechanistic studies showed piRNA-46403 directly binds to YBX1, sequestering it away from its RNA targets.
YBX1 normally binds to m5C (5-methylcytosine)-modified USP18 mRNA, stabilizing the transcript.
The piRNA-46403/YBX1 interaction competitively disrupts this m5C-dependent mRNA stabilization mechanism.
Results
Disruption of YBX1 binding to m5C-modified USP18 mRNA reduces USP18 mRNA stability, thereby triggering ferroptosis in Sertoli cells.
Reduced binding of YBX1 to USP18 mRNA leads to decreased USP18 mRNA stability and consequently lower USP18 expression.
Loss of USP18 expression was mechanistically linked to the induction of ferroptosis in Sertoli cells.
This establishes a direct mechanistic chain: piRNA-46403 → YBX1 sequestration → m5C-USP18 mRNA destabilization → USP18 downregulation → ferroptosis.
Results
The study elucidates a novel piRNA-46403/YBX1/m5C-modified USP18 regulatory axis in the male reproductive system.
This regulatory axis represents a previously unreported mechanism linking piRNA biology, RNA m5C modification, and RNA-binding protein function in testicular pathology.
The axis connects epigenetic RNA modification (m5C) with post-transcriptional regulation via YBX1 and piRNA-mediated decoy activity.
piRNA-46403 is positioned as a promising therapeutic target for mitigating VC-mediated infertility based on these mechanistic findings.
What This Means
Varicocele, a condition involving enlarged veins in the scrotum, is one of the leading causes of male infertility, but the molecular reasons why it damages sperm production have not been well understood. This study found that a specific type of cell death called ferroptosis — a form of programmed cell death driven by iron and oxidative damage — occurs in Sertoli cells (the testicular 'nurse' cells that support sperm development) in men with varicocele. When researchers blocked this ferroptosis process using drugs in animal models, sperm production improved, suggesting this cell death pathway is a key driver of infertility in varicocele.
The researchers traced this ferroptosis back to a small RNA molecule called piRNA-46403, which was found at abnormally high levels in testicular tissue from varicocele patients with poor sperm motility. This piRNA works like a molecular 'decoy' — it grabs onto a protein called YBX1 and prevents it from doing its normal job. YBX1's normal job is to stabilize the messenger RNA of a gene called USP18 by recognizing a chemical tag (called m5C) on that RNA. When piRNA-46403 pulls YBX1 away, USP18 RNA becomes unstable, USP18 protein levels drop, and Sertoli cells undergo ferroptosis. This dying of Sertoli cells then causes nearby sperm-producing cells (spermatogonia) to undergo apoptosis (another form of cell death), impairing sperm production overall.
This research suggests that piRNA-46403 could be a therapeutic target for treating varicocele-associated male infertility. By silencing this piRNA, it may be possible to prevent Sertoli cell death and restore sperm production. The findings also reveal a new type of molecular regulatory chain — involving small RNAs, RNA-binding proteins, and chemical RNA modifications — that controls testicular cell survival, which could open new avenues for understanding and treating male reproductive disorders more broadly.
Fang X, Song L, Liu D, Xin Z, Pang W, Tong Q, et al.. (2026). piRNA-46403 Promotes Sertoli Cell Ferroptosis via Disrupting m5C-dependent USP18 mRNA Stabilization in Varicocele-mediated Infertility.. International journal of biological sciences. https://doi.org/10.7150/ijbs.137298