Effects of Adipose Tissue-Specific Knockout of Delta-like Non-Canonical Notch Ligand 1 on Lipid Metabolism in Mice

Delta-like non-canonical Notch ligand 1 (DLK1), which inhibits the differentiation of precursor adipocytes, is a recognized marker gene for precursor adipocytes. Lipids play a crucial role in energy storage and metabolism as a vital determinant of beef quality. In this study, we investigated the mechanism of the DLK1 gene in lipid metabolism by constructing adipose tissue-specific knockout mice. We examined some phenotypic traits, including body weight, liver coefficient, fat index, the content of triglyceride (TG) and cholesterol (CHOL) in abdominal white adipose tissue (WAT) and blood. Subsequently, the fatty acid content and genes related to lipid metabolism expression were detected in DLK1(-/-) and wild-type mice via GC-MS/MS analysis and quantitative real-time PCR (qRT-PCR), respectively. The results illustrated that DLK1(-/-) mice exhibited significant abdominal fat deposition compared to wild-type mice. HE staining and immunohistochemistry (IHC) results showed that the white adipocytes of DLK1(-/-) mice were larger, and the protein expression level of DLK1(-/-) was significantly lower. Regarding the blood biochemical parameters of female mice, DLK1(-/-) mice had a strikingly higher triglyceride content (p < 0.001). The fatty acid content in DLK1(-/-) mice was generally reduced. There was a significant reduction in the expression levels of the majority of genes that play a crucial role in lipid metabolism. This study reveals the molecular regulatory mechanism of fat metabolism in mice and provides a molecular basis and reference for the future application of the DLK1 gene in the breeding of beef cattle with an excellent meat quality traits. It also provides a molecular basis for unravelling the complex and subtle relationship between adipose tissue and health.