Molecular Mechanism Research Of PGC-1β Gene Regulating Broiler Abdominal Fat Deposition And Chicken Preadipocyte Lipid Deposition

Adipose is an important tissue which plays a crucial role in animal life during growth and reproduction. The change of meat quality, obesity and other metabolic diseases are closely linked in the fat deposition of poultry and the fat deposition of poultry mainly by adipocytes proliferation and differentiation of complete. Understanding fat deposition of poultry is of great significance for poultry breeding and treatment of the human metabolic diseases. PGC-1β, as an adjuvant activator of adipocyte differentiation markers gene PPARγ, plays an important role in metabolic regulation by activating transcription factors. Many studies have shown that PGC-1β is closely related to the formation of fat, but the fat deposition is a complex process with so numerous signaling pathways and genes involved, the mechanism is still unclear, and few researches on poultry.In order to study on the effect of PGC-1β gene on fat deposition of broiler in vivo and lipid metabolism of poultry adipocytes in vitro, feed intake levels were changed to feed broiler in vivo to 70days of age. Then collecting chicken preadipocytes and 300μM oleate was used to treat chicken preadipocytes. Finally, we constructed RNAi vector targeting of chicken PGC-1β gene and transfected into chicken adipocytes.To study on the effect of PGC-1β gene on fat deposition in vivo, we changed the feed intake levels (110%,100%,90%) to feed AA broiler for 70 days of age, then detected the mRNA expression levels of PGC-1β and fat metabolism related genes (PPARγ, C/EBPα, SREBP-1c, FAS and A-FABP) in liver and abdominal fat in different feed intake levels by Real-time PCR. The main results are as follows:(1) Weight gain and abdominal fat deposition of the broiler were decreased with the change of the feed intake levels. (2) Expression levels of PPARγ (28d,70d), SREBP-1c (70d) and FAS (70d) in abdominal fat and PPARγ (70d), SREBP-1c (70d), FAS (70d) in liver were gradually increased with the increase feed intake levels. And the mRNA expression levels of A-FABP (28d,49d, and 70d) in abdominal fat gradually were decreased with the increase feed intake levels. (3) Expression levels of PGC-1β in abdominal fat (70d) and in liver (49d,70d) were gradually increased with the increase feed intake levels.To investigate the mRNA expression levels of PGC-1β gene during chicken preadipocytes differentiation in vitro,14 days chicks were used for preadipocytes culture, then primary preadipocytes were induced for differentiation by oleate. Oil red O staining were used to determine the changed of differentiation of chicken fat precursor cells morphological changes. We detected the mRNA expression levels of PGC-1β and the differentiation marker gene (PPARy, C/EBPa) during chicken adipocytes differentiation by Real-time PCR. The main results are as follows:(1) Morphological changes of chicken adipocytes differentiation consistent with the typical characteristics of animal adipocytes differentiation. Many small lipid droplets were generated in the beginning of differentiation, then the lipid droplets gather together and stored in the adipocytes with the deepening degree of differentiation. (2) PPARy is highly expressed in early differentiation, while C/EBPa mRNA expression is increased in the late differentiation; (3) Expression levels of PGC-1β gene were gradually increased with deepening degree of differentiation.To study the influence of PGC-1β gene on chicken adipocytes differentiation, we constructed RNAi vectors targeting of chicken PGC-1(3 gene and transfected into chicken adipocytes. Oil red O staining and CCK-8 cell proliferation assay was used to determine the changes of triglyceride accumulation in cellular after transfection and determine the changes of cell proliferation after transfection, respectively. PGC-1β and adipocyte differentiation related gene (PPARy, C/EBPa, SREBP-1c, FAS and A-FABP) mRNA expression changes were detected by Real-time PCR. The main research results are as follows:(1) after transfection, PGC-1β gene mRNA and protein expression were significantly lower. (2) PGC-1β interference significantly decreased the triglyceride accumulation in cellular. (3) Cell proliferation was not affected by PGC-1β interference significantly. (4) PGC-1β interference significantly decreased the mRNA expression of PPARy, SREBP-1c and FAS. The results indicate that PGC-1β gene was an key factor in the regulation of chicken adipocytes differentiation.In this study, we concluded that the differences of feed intake level have a significant impact on the broiler body weight and fat deposition, and PGC-1β participates in chicken fat metabolism regulation. PGC-1β interference caused a signigicant decline of PPARy and SREBP-1c expression, which indicates that PGC-1β may regulate fat cell differentiation by regulate the mRNA expression of PPARy or SREBP-1β.