Nissen P M, Oksbjerg N
Department of Food Science, Faculty of Agricultural Sciences, University of Aarhus, PO Box 50, DK-8830 Tjele, Denmark.
Animal. 2009 May;3(5):703-9. doi: 10.1017/S1751731109003929.
Postnatal muscle growth is dependent on satellite cell (SC) proliferation, differentiation and fusion to increase the DNA content of existing muscle fibres and thereby the capacity to synthesize protein. The purpose of the present study was to examine the ability of isolated SCs from low, medium and high weaning weight litter mates of pigs to proliferate and differentiate, and to affect protein synthesis and degradation after fusion into myotubes. At 6 weeks of age, SCs from the lowest weight (LW), medium weight (MW) and highest weight (HW) female pigs within eight litters were isolated. Thereby, eight cultures of SCs were established for each of the three weight groups within litter, representing three groups of SCs from pigs exhibiting differences in postnatal muscle growth performance. Proliferation was estimated as the number of viable cells at different time points after seeding. SC differentiation was evaluated by measuring the activity of the muscle-specific enzyme, creatine phosphokinase, and protein synthesis and degradation were measured by incorporation and release of 3H-tyrosine, respectively. A tendency towards a difference in proliferation between SC cultures was found (P = 0.09). This was evident as the number of viable cells at day 3 was lower in cultures from LW pigs than from HW (P < 0.05) and MW (P < 0.01) pigs. Differentiation was significantly different between cultures (P < 0.05). There was a significant difference between LW and MW cultures at 72 h (P < 0.05), and a tendency towards a difference between LW and HW cultures at 45 h (P = 0.07). Protein synthesis per μg protein or per μg DNA did not differ among SC cultures from LW, MW and HW pigs. Neither did protein degradation rate differ significantly among SC cultures from LW, MW and HW pigs. Overall, the results show that SCs from LW pigs seem to proliferate and differentiate at a slower rate than SCs from MW and HW pigs. The results found in this study show no difference in the ability of SCs to affect protein synthesis or degradation between SCs from litter mates exhibiting different growth rates in vivo.
出生后肌肉生长依赖于卫星细胞（SC）的增殖、分化和融合，以增加现有肌纤维的DNA含量，从而提高蛋白质合成能力。本研究的目的是检测从低、中、高断奶体重的同窝仔猪中分离出的卫星细胞的增殖和分化能力，以及融合成肌管后对蛋白质合成和降解的影响。6周龄时，从8窝仔猪中体重最低（LW）、中等体重（MW）和最高体重（HW）的雌性仔猪中分离卫星细胞。因此，每窝内三个体重组分别建立了8种卫星细胞培养物，代表了三组出生后肌肉生长性能存在差异的仔猪的卫星细胞。增殖以接种后不同时间点的活细胞数量来估计。通过测量肌肉特异性酶肌酸磷酸激酶的活性来评估卫星细胞的分化，分别通过3H-酪氨酸的掺入和释放来测量蛋白质合成和降解。发现卫星细胞培养物之间的增殖存在差异趋势（P = 0.09）。这表现为第3天LW仔猪培养物中的活细胞数量低于HW仔猪（P < 0.05）和MW仔猪（P < 0.01）培养物中的活细胞数量。培养物之间的分化存在显著差异（P < 0.05）。LW和MW培养物在72小时时存在显著差异（P < 0.05），LW和HW培养物在45小时时存在差异趋势（P = 0.07）。LW、MW和HW仔猪的卫星细胞培养物中每微克蛋白质或每微克DNA的蛋白质合成没有差异。LW、MW和HW仔猪的卫星细胞培养物之间的蛋白质降解率也没有显著差异。总体而言，结果表明LW仔猪的卫星细胞增殖和分化速度似乎比MW和HW仔猪的卫星细胞慢。本研究结果表明，在体内生长速度不同的同窝仔猪的卫星细胞之间，其影响蛋白质合成或降解的能力没有差异。
