Regulatory mechanisms of microRNAs in reproductive toxicity induced by environmental pollutants: a mini review.

Environmental pollutants rise serious threats to human reproductive health, leading to disrupted gametogenesis, hormonal imbalance, and decreased fertility. Increasing evidence highlights microRNAs (miRNAs) as crucial post-transcriptional regulators mediating these toxic effects. miRNAs are small non-coding RNAs of about 22 nucleotides that regulate gene expression by binding to target messenger RNAs (mRNAs) to suppress translation or promote degradation, thereby influencing cellular processes such as proliferation, differentiation, apoptosis, and stress response. Recent studies have shown that environmental pollutants can significantly alter miRNA expression profiles, thereby modulating key molecular pathways involved in reproductive toxicity. Among the miRNAs identified, miR-199a-5p, miR-132-3p, miR-450b-3p, miR-21-5p, and miR-210-3p are most consistently dysregulated across various pollutant exposures. These miRNAs are implicated in signaling pathways including HIF-1/NF-κB, BCL2-CASPASE, Layilin-YAP, and TLR4/NLRP3, forming an interconnected regulatory network that governs apoptosis, inflammation, energy metabolism, and steroidogenesis. Collectively, these findings suggest that miRNA dysregulation represents a key epigenetic mechanism linking environmental exposure to adverse reproductive outcomes. Moreover, specific miRNAs may serve as sensitive biomarkers for pollutant exposure and early reproductive impairment. Further mechanistic and translational research is needed to clarify their regulatory roles and to inform preventive strategies aimed at reducing reproductive risks associated with environmental contaminants.