Effects Of PGC-1β On The Preadipocytes Differentiation And Mitochondria Function In Rat And Its Action Mechanism

Fat tissue plays great role in energy metabolism and the disproportion of fat deposition could cause metabolic disorder. While the key element of body fat deposition is adipocyte proliferation and differentiation, so it is significant to study the molecule mechanism of adipocyte differentiation. The present study demonstates that mitochondria multiplely proliferate in 3T3-L1 adipocytes, and dysfunction of mitochondria cause body fat abnormally deposite or impede adipocyte differentiation( fat deposition decrease). However, the specific function of mitochondria is not clear. The previous study on mitochondria mostly concentrated on prophase and mature period of adipocyte differentiation, but time-spatial development changes of mitochondria in adipocyte differentiation are also not clear.The expression of PGC-1βis increased in adipocyte differentiation, and it is close with mitochondria biosynthesis and energy metabolism in vivo. Nevertheless, whether PGC-1βregulates mitochondria biosynthesis and whether it is related with white adipocyte differentiation need further studies.The regular pattern of mitochondrial development, the effect of mitochondria damage on preadipocytes differentiation, and the time-spatial expression of PGC-1 family and oxidate-respiration related genes during rat preadipocytes differentiating process were investigated with SQ RT-PCR, immunofluorescence histochemistry, flow cytometry, electron microscope and HPLC technique。And these provided data for study on new genes related fat deposition and control and treat obese and many metabolism diseases, and provided the information and basis for preventing and treating obese and many metabolism diseases by gene regulation.The results are as follows:1. Mitochondrial mass was increased during the rat preadipocytes differentiation, and the mRNA level of the related gene such as PGC-1β, Cyt c and MDH was also increased, while ATP biosynthesis was reduced.2. Rosiglitazone stimulate adipocyte differerntion accompany with increase mass of mitochondrial and cristae, while promote mRNA expression of MDH,Cytc,PGC-1βand respiratory function of mitochondrial.3. Rotenone(2-4umol/L) remarkably inhibition adipocytes differention, and reduced the ATP synthesis. The respiratory function of mitochondrial was impaired result in reduce ATP synthesis. The expression of PGC-1βwas also decreased, while the mRNA level of marked genes of adipocytes differention such as C/EBPα、SREBP-1 and PPARγwere significantly decreased , also for FAS , but no change in LPL level.4. PGC-1βsiRNA reduce mRNA expression of mitochondrial-related gene, such as MDH, NRF1 and CPT1 , the ATP and triglyceride biosynthesis were also decreased , while reduce PPARγ,SREBP-1c and FAS in mRNA and protein level,these suggest that PGC-1βmay coordinate the mitochondrial biosynthesis by affect its functional genes, it could also rugulate the adipocyte triglyeride.5. Over-expression PGC-1βcould promote preadipocyte differerntion in 3T3-L1 cell lines, and this methnism will be finished by stimulate expression of CPT1,MDH, PPARγand FAS which were the maked gene in mitochondrial biosynthesis and adipocyte differention.Above all, mitochondrial development during adipocyte differentiation has the certain regular pattern, which provide enegy for this period. The function of mitochondria was enhanced by treated with rosiglitazone. And mitochondrial damage can impede adipocyte differentiation. Only PGC-1βwhich was one member of PGC-1 family significantly up-regulated during adipocyte differentiation. Silencing of PGC-1βcould inhibit the expression of mitochondria related genes and biosynthesis of ATP. Therefore, all results suggested that PGC-1βplays an important role in regulating mitochondrial development in white adipocytes. Meanwhile, silencing of PGC-1βstrikingly inhibited triglyceride synthesis and the period of adipocyte differentiation. The suppression mechanism is through inhibiting mitochondrial biosynthesis and adipocyte differentiation related genes. In addition, the results of overexpression of PGC-1βin 3T3-L1 adipocytes also certify the importance of PGC-1β.