Function of miRNAs in Conferring Neuroprotection through a Tailored Peptide Derived from Snake Venom Nerve Growth Factor in Response to Paraquat-Induced Toxicity in Caenorhabditis elegans.

Parkinson's disease (PD) is a major global health challenge, shaped by environmental factors and the accumulation of alpha-synuclein. MicroRNAs (miRNAs), key regulators of gene expression, play critical roles in neurodegeneration, and their dysregulation has been linked to PD development. Paraquat (PQ), a widely used herbicide, can induce PD-like symptoms by generating reactive oxygen species, impairing mitochondrial function, promoting alpha-synuclein aggregation, and triggering apoptosis of dopaminergic neurons. These effects ultimately alter the miRNA expression profiles. Our previous research demonstrated that the computationally designed snake venom-inspired peptide, heptadeca-neuropeptide (HNP), protects against PQ-induced toxicity and neurodegeneration in vitro (in rat PC-12 cells) and in vivo (in Caenorhabditis elegans). In this study, miRNA microarray analyses in C. elegans treated with mouse 2.5S nerve growth factor (NGF) or HNP revealed distinct differential miRNA expression profiles, with significant upregulation of cel-miR-1-3p, cel-miR-255-3p, cel-miR-62, cel-miR-358-3p, and cel-miR-1820-5p relative to the control. Pathway analyses implicated these miRNAs in neuroprotective signaling pathways, including PI3K, Wnt/β-catenin, and TGF-β, while downregulated miRNAs aligned with apoptosis, p53, and innate immunity pathways, underscoring HNP's neuroprotective effects via miRNA modulation in C. elegans. Furthermore, we selected 31 predicted target genes from those above five upregulated miRNAs, which are involved in gene regulation, suppression of proinflammatory cytokines, mitochondrial metabolism, protein synthesis, and transmembrane transport. qRT-PCR analyses revealed a trend toward reduced expression of these targets following PQ treatment, whereas HNP pretreatment significantly restored their expression; however, NGF pretreatment did not elicit significant changes compared to the control. Comparative miRNA profiling showed that NGF/HNP restored PQ-induced alterations, with HNP enhancing alpha-synuclein clearance by significantly upregulating miR-4813-3p. These findings position HNP as a promising candidate for miRNA-targeted interventions in PD and related disorders.