采用荧光定量PCR技术检测了长白猪和梅山猪的背最长肌组织中胰岛素样生长因子1和2(IGF-1和-2)、胰岛素样生长因子1受体和2受体(IGF-1R和-2R)、胰岛素样生长因子结合蛋白3和5(IGFBP-3和-5)基因mRNA丰度在初生(0月龄)、1、2、3、4和5月龄间的表达变化并分析品种间和不同月龄间基因表达的差异及其对肌肉生长发育的影响。结果表明: 两猪种出生后IGF-1 mRNA表达量均表现为逐渐上调, 而IGF-2则恰好相反, 表现为逐渐下调。这与IGF-2主要在胚胎期发挥作用, 而IGF-1则主要在动物个体出生后才发挥促进细胞增殖和个体发育功能的特点相符。IGFRs mRNA与IGFs mRNA 表达的发育性变化模式并不相似, 提示背最长肌组织中IGFRs mRNA 的表达可能没有受到组织局部产生的IGFs调节。长白猪的IGF-1R、IGF-2R 和IGFBP-3 mRNA表达量均在2月龄时达到最高峰, 提示2月龄可能是长白猪IGFs系统发挥作用最为明显的生长发育阶段。以上结果初步揭示猪生长发育过程中胰岛素样生长因子系统基因表达的发育性变化模式和品种差异, 为深入研究胰岛素样生长因子系统基因的相互调控机制提供了基础数据。
Real-time fluorescence quantitative PCR was applied to investigate the developmental expression patterns of insulin like growth factor-1 and -2 (IGF-1 and -2), insulin like growth factor receptor -1 and -2 (IGF-1R and -2R), insulin like growth factor binding protein-3 and -5 (IGFBP-3 and -5) genes at the age of birth (0), 1, 2, 3, 4, and 5 months in long-issimus dorsi muscle of Landrace and Meishan pigs. The expression level of IGF-1 exhibited up-regulation, in contrast, the expression level of IGF-2 showed down-regulation after birth in the two pig breeds. These findings are consistent with the previous knowledge that IGF-2 is mainly expressed during the embryonic phase, IGF-1 is mainly expressed during the postnatal period, which could promote cell proliferation and ontogenesis. The expression patterns of IGFRs and IGFs were dissimilar from 0 to 5 months in the two pig breeds, which suggest that the expression changes of IGFRs may not be sub-jected to the regulation by local secretion of IGFs. Strikingly, at the age of 2 months, the expression levels of IGF-1R, IGF-2R, and IGFBP-3 reached their maximum peak values in Landrace pigs, which suggest that the 2 months after birth may be the most important growth stage for genes of insulin-like growth factors (IGFs) system to exert their biological functions from birth to 5 months. These results indicate that the mRNAs of IGFs system genes exhibit specific develop-mental expression changes between Landrace and Meishan pigs, and provides some data for further study on the mutual regulation mechanism of genes in IGFs system.
