Tissue Distribution Of PGC-1α, Mitochondrial-related Gene In Pig And Effects Of Leptin On The Expression Of PGC-1α And UCPs MRNA

Mitochondrium is an important subcellular organelle, which is widely distributed in eukaryocyte. It can decompose sugar, protein and lipid through respiration, release ATP, and then provide energy for organism. It has been identified that mitochondrium is not only closely related to energy metabolism, but also a key factor affecting tenderness and flavor of meat quality. In this study, pig was used as experimental animal to do follow works: (1) the tissue differential expression of mitochondrium related genes (PGC-1α,UCP2,UCP3,Cyt-c and CPT-Ⅰ) was analyzed by SQ RT-PCR. (2) The culture system of pig muscle satellite cell in vitro was established. (3) The effects of exogenous leptin on the expression PGC-1αand UCPs mRNA in pig myoblasts was investigated. The results are as follows:PGC-1αmRNA was widely expressed in heart, liver, muscle, lung, kidney, spleen, subcutaneous adipose and visceral adipose. Among them, PGC-1αmRNA was highest expressed in heart, liver and muscle. UCP2 expression was detected in muscle, subcutaneous adipose, kidney, spleen and visceral adipose and not tested in heart and lung. UCP2 expression was highest in kidney, then muscle and lowest in liver. In addition, UCP2 expression did not have significance between visceral adipose and subcutaneous adipose. UCP3 was abundant in muscle, subcutaneous adipose and visceral adipose and did not exist in other tissues. Significance test showed that UCP3 mRNA expression was not significant among muscle, subcutaneous adipose and visceral adipose. It indicated that Cyt-c was widely distributed in heart, liver, muscle, subcutaneous adipose, kidney, spleen, visceral adipose and lung, which was highest expressed in liver and higher in heart, kidney and spleen. Moreover, Cyt-c expression in subcutaneous adipose was higher than that of muscle (P<0.05).1 Pig muscle sample were minced and respectively digested with pronase, trypsin and collagenase I. The results showed that the amount of muscle satellite cell digested with pronase significantly higher than with trypsin and collagenase. The effect of collagenase was mostly poor in a certain digested time. The digest contained many muscle bundles and obtained seldom satellite cells. There was no difference in live ratio among three enzymes. The cell purity digested by pronase was 95% by desmin immunohitochemistry stains test and MyoG and MyoD was expressed in cells cultured day 7, showing that muscle satellite cell was successfully isolated.2 SQ RT-PCR showed that both 30 and 100 nmol/L Leptin could promote the expression of PGC-1αmRNA in myoblasts. 100 nmol/L Leptin treated for 12 h promoted PGC-1αmRNA expression. PGC-1αmRNA expression was significantly higher than control when cells was treated with Leptin for 24 h(P<0.05). 30 nmol/L Leptin treated for 24 h enhanced PGC-1αmRNA expression, but its effects was significantly lower than 100 nmol/L group.3 SQ RT-PCR showed that 30 nmol/L Leptin markedly promoted the UCP2 mRNA expression of myoblasts, and it was higher when treated for 24 h than that of 12h (P<0.05). The effect 100 nmol/L Leptin on UCP2 mRNA expression was significantly lower than that of 30 nmol/L Leptin in 12 and 24 h, but markedly higher than that of control(P<0.05). Additionally, the mRNA expression of UCP3 was not significantly different when treated by 30 and 100 nmol/L Leptin compared to control in myoblasts(P<0.05).In conclusion, the expressional level of mitochondrial-related gene has significantly tissues difference. PGC-1a is abundant in tissues contained multiple mitochondrial, hinting that it is closely related to mitochondrial development. The tissue expression of other genes has difference according to energy demand and metabolic characteristic of tissue. Also, exogenous leptin influences the expression of PGC-1αand UCPs, suggesting that Leptin affects energy metabolism of organism through regulating mitochondrial. It can provide theoretical reference for animal muscle development and controlling human metabolic diseases.