Epigenetic Legacy: The Role of Sperm miRNAs in the Paternal Inheritance of Diabetes and Obesity Development.

In recent decades, obesity and diabetes have reached pandemic levels, with obesity now recognised as a major health risk factor. Evidence shows that metabolic diseases are more pronounced in the offspring of malnourished parents, suggesting that predisposition can be inherited via epigenetic information in gametes. This has sparked growing interest in small regulatory RNAs in sperm as carriers of epigenetic inheritance. However, the functional annotation of dysregulated sperm microRNAs (miRNAs) in obesity and diabetes remains limited. This work addresses this gap by analysing publicly available datasets of diet-regulated sperm miRNAs and linking them to genes functionally associated with obesity and diabetes. We systematically identified diet-responsive sperm miRNAs and overlapped their predicted targets with genes associated with metabolic phenotypes, as catalogued by the International Mouse Phenotyping Consortium (IMPC). First, in a sequence-based approach, we uncovered 11,272 and 6528 potential target genes for miRNAs regulated by the acute and chronic HFD interventions, respectively. Second, by overlapping these predicted target genes of sperm miRNAs with our IMPC-derived list of 889 genes associated with obesity and diabetes, we identified 805 acute- and 546 chronic-HFD predicted response genes. This approach thus associates function with regulated miRNAs and revealed distinct miRNA-gene networks in acute versus chronic HFD models, including shared nodes in pathways related to insulin signalling, lipid metabolism, and β-cell function. To support further research, we provide the field with the ShinyFatSperm App (https://reproproteomics.shinyapps.io/ShinyFatSperm/), which facilitates the functional interpretation of diet-regulated sperm miRNAs and enables users to explore their roles in the intergenerational transmission of metabolic disease risk. Taken together, our findings reinforce the concept that paternal dietary exposures can influence offspring health through epididymal- and sperm-borne miRNAs, and related epigenetic mechanisms. This work provides a roadmap for hypothesis-driven investigation into the intergenerational inheritance of metabolic diseases and highlights the urgent need for translational strategies to interrupt this cycle.