Sex-dependent molecular architecture and selective cargo organization of gonadal extracellular vesicles in an echinoderm model

Sexual dimorphism in reproductive strategies requires precise metabolic signaling. However, the mechanisms linking cellular communication to sex specific phenotypes remain poorly understood. Invertebrates with ancestral endocrine pathways may offer a useful evolutionary window into these foundational regulatory networks. Here, we utilize the echinoderm Apostichopus japonicus to investigate how extracellular vesicles (EVs) mediate sex-biased metabolic partitioning. EVs were isolated from mature gonads of both sexes. Through targeted metabolomics analysis of these gonadal EVs, we identified ten steroid-related metabolites showing profound sexual divergence. Female-derived EVs are preferentially enriched in upstream steroid precursors (including pregnenolone and DHEA sulfate) and multiple corticosteroids (cortisol, corticosterone, aldosterone, 11-deoxycortisol, 21-deoxycortisol), establishing a stable precursor reservoir essential for oogenesis and ovarian maintenance. In contrast, male EVs prioritize downstream androstenedione derivatives tailored for rapid functional responses during spermatogenesis. Multivariate analysis confirmed clear sex-specific separation of EV metabolic cargo, mapping directly onto highly conserved steroidogenesis and corticosteroid pathways. Collectively, our findings suggest that EVs may contribute to reproductive specialization by carrying sex-biased metabolic signals. By demonstrating that vesicular metabolite partitioning maintains distinct reproductive phenotypes in Apostichopus japonicus, this study provides a new mechanistic framework that may inform the evolution of sexual dimorphism in marine invertebrates.