Targeting the PRMT5-Nur77 methylation axis enhances endometrial decidualization capacity and female fertility in preclinical models

Defective endometrial decidualization is one major cause of female infertility, yet the underlying mechanisms remain elusive. Here, we identified that protein arginine methyltransferase 5 (PRMT5) which was upregulated during decidualization and by progesterone stimulation, is markedly down-regulated in the endometria of patients with recurrent implantation failure (RIF), along with a global reduction of symmetric dimethylarginine (sDMA). Uterine stromal-specific ablation of Prmt5 in mouse severely impaired decidualization leading to infertility. A multi‑omics analysis in human endometrial stromal cells (EnSCs) revealed that PRMT5 promoted decidualization primarily by catalyzing sDMA at arginine 346 (R346) of the orphan nuclear receptor Nur77, which directs its proper chromatin occupancy. Targeting the PRMT5-Nur77 methylation axis, we designed a peptide, Pep‑Nur77-R346K, which rescued the decidualization of multiple preclinical models: PRMT5 deficient human EnSCs, both genetic knockout (Prmt5d/d) and pharmacologically inhibited mouse models, an estrogen deficient mouse model, and, more importantly, the primary RIF EnSCs. In a retrospective cohort of 114 participants, the correlated reductions of endometrial PRMT5/Nur77-R346me2s was confirmed, which demonstrated robust predictive value for pregnancy outcome. Our work establishes the PRMT5‑Nur77 methylation axis as a key regulator of endometrial receptivity, and highlights both a novel diagnostic biomarker and a peptide‑based therapeutic potential for fertility.