Abstract:

The aim of this study was to understand the molecular pathological mechanisms of subcutaneous adipose dysfunction in pigs susceptible to metabolic diseases, and to investigate the correlation between disturbances of energy metabolism in subcutaneous adipose tissue and epigenetic regulation. The study selected wild-type male Bama pigs with similar weight and good health at 6 months old, as well as transgenic pigs susceptible to metabolic diseases, and divided them into 4 groups after being induced by a high-fat high-sugar diet (HFHSD) for 3 or 12 months. The wild-type groups were named WT-3 (n=5) and WT-12 (n=5), while the transgenic groups were named TG-3 (n=8) and TG-12 (n=4). Firstly, the animals were evaluated by serum biochemistry, containing the concentrations of triglycerides, free fatty acids, leptin, and adiponectin. Then, the animals were subjected to histopathological evaluation, and molecular features and enriched signaling pathways of metabolic disorders were obtained through transcriptome sequencing. Subsequently, key genes, metabolites, and epigenetic modifications were detected using qPCR, Western blot, and ELISA. The results of serum biochemical assay and histopathological evaluation showed that both transgenic and diet induction could cause adipose tissue dysfunction, and the pathological injury of transgenic combined diet induction group was more serious. Transcriptome sequencing results showed that adipose tissue dysfunction was characterized by impaired mitochondrial oxidative phosphorylation and decreased glucose and lipid metabolism and protein synthesis in adipose tissue. qPCR results showed that the expression of mitochondria-encoded genes was significantly down-regulated in TG-12 group. WB results showed that the key genes regulating glucose and lipid metabolism, ACLY, ACSS2 and FASN, were significantly down-regulated in TG-12 group. ELISA results showed that the content of acetyl-coA, the key intermediate metabolite, was decreased. Moreover, WB verified that the reduction of histone acetylation, which has a wide regulatory role in gene expression, may be the main cause of adipose dysfunction. The use of metabolic disease susceptible pigs reveals that reduced subcutaneous adipose mitochondrial function exerts extensive gene expression inhibitory effects through down-regulation of acetyl coenzyme A content and histone acetylation levels via epigenetic modification, providing a model and reference data for the treatment of obesity-associated subcutaneous dysfunction diseases in humans.

Key words: transgenic pig, subcutaneous adipose tissue, RNA-Seq, mitochondria, histone acetylation