ELOVL5 regulates bovine intramuscular fat deposition by balancing adipocyte proliferation and differentiation

Context Intramuscular fat (IMF) deposition is a key determinant of beef quality, influencing flavor, tenderness, and juiciness. Although the molecular drivers of adipogenesis are well-characterized in monogastric models, the regulatory networks specific to ruminants remain incompletely defined. Aim In this study, we identify the fatty acid elongase ELOVL5 as a pivotal modulator of adipocyte development in cattle. Using primary bovine preadipocytes, we performed both loss-of-function (siRNA-mediated silencing) and gain-of-function (plasmid overexpression) experiments to elucidate the role of ELOVL5. Methods Primary bovine preadipocytes were isolated from Longissimus dorsi muscle of cattle and cultured under standard adipogenic conditions. Functional perturbations were performed via (1) siRNA-mediated ELOVL5 knockdown and (2) plasmid-driven ELOVL5 overexpression. Proliferation was assessed using CCK-8 assays (viability), EdU incorporation (DNA synthesis), and quantitative polymerase chain reaction (qPCR) for cell cycle regulators (*CDK2/4/6*). Differentiation was evaluated through Oil Red O staining (lipid accumulation) and qPCR/western blot analysis of adipogenic markers (*PPARγ, C/EBPα, FABP4*). Key results ELOVL5 knockdown significantly enhanced preadipocyte proliferation, as demonstrated by increased expression of cell cycle regulators (CDK2, CDK4, CDK6), elevated cell viability (CCK-8 assay), and greater DNA synthesis (EdU incorporation). In contrast, overexpression of ELOVL5 suppressed these proliferative indices. However, ELOVL5 exhibited an inverse effect on adipogenic differentiation, namely, knockdown attenuated lipid accumulation and downregulated key adipogenic transcription factors (PPARγ, C/EBPα, FABP4), whereas overexpression markedly promoted lipid deposition and expression of these genes. Conclusions Taken together, these findings establish ELOVL5 as a bifunctional regulator that restrains preadipocyte proliferation while promoting terminal differentiation, positioning it as a critical molecular node in bovine adipogenesis. Implications This dual role underscores the potential of ELOVL5 as a genetic target for modulating intramuscular fat content in cattle, with implications for enhancing beef quality through precision breeding and functional genomics.