Characterization and Validation of A-to-I RNA Editing Events Reveal Their Potential Regulatory Role in Bovine...

Intramuscular fat (IMF) content is a critical determinant of meat quality, directly influencing flavor and palatability. RNA editing, a prevalent posttranscriptional modification in mammals, has been extensively investigated in cattle; however, its role in bovine intramuscular fat deposition remains poorly understood. Here, we performed a comprehensive analysis of RNA editing differences in the longissimus dorsi muscle between cattle groups with divergent IMF content to identify editing sites potentially associated with IMF deposition. A total of 283 581 RNA editing sites (RESs) were identified from transcriptomic data of cattle with contrasting IMF phenotypes. Among the differential A-to-I editing sites located in coding sequences, 14 led to amino acid alterations, including an editing event in MYBPH, a gene with important functions in muscle and adipose tissues. Differential A-to-I editing sites in the 3' UTR resulted in altered miRNA binding patterns: 30 sites led to loss of miRNA binding, whereas 16 sites gained novel miRNA binding capacity. Dual-luciferase reporter assays confirmed that the editing site chr2:106787199 in the 3' UTR of PRKAG3 affects binding by bta-miR-23b-5p. Functional validation experiments demonstrated that bta-miR-23b-5p promotes PRKAG3 expression, and overexpression of PRKAG3 suppresses preadipocyte differentiation and lipid droplet formation. Collectively, these findings uncover a regulatory role for RESs in IMF deposition and provide new insights into the functional significance of RNA editing in bovine intramuscular fat accumulation.