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为研究甘氨酸(Glycine,Gly)对肝脏IGF-1表达和分泌的影响,本文一方面采用不同浓度Gly离体处理HepG2肝细胞,另一方面采用小鼠尾静脉注射1.0 g/kg Gly和等摩尔Ala,0.5 h和1 h后采集血液、肝脏和肌肉样品。研究采用定量PCR检测了IGF-1以及IGFBPs基因表达水平的影响,同时运用Western blot法分析了肝细胞和肝脏生长激素受体通路(JAK2/STAT5)与肌肉IGF-I受体通路(ERK/Akt/m TOR)的变化。研究结果发现,不同浓度的Gly能剂量依赖性提高HepG2细胞IGF-1的蛋白和m RNA表达水平;1.0 g/kg Gly能显著提高小鼠血清中的IGF-1和白蛋白含量,且极显著提高肝脏IGF-1和IGFBP-3 m RNA水平,下调IGFBP-1 m RNA水平。细胞和活体试验均表明,Gly能够有效激活肝细胞和肝脏JAK2/STAT5信号通路,同时提高腓肠肌IGF-I受体信号通路磷酸化水平。这些研究说明甘氨酸可能直接提高肝脏生长激素受体信号通路敏感性,从而促进IGF-1的表达和分泌。研究结果为深入揭示甘氨酸的分子营养学功能和作用机制提供了实验依据。
In order to study the effect of Glycine (Gly) on the expression and secretion of hepatic IGF-1, HepG2 hepatocytes were treated ex vivo with different concentrations of Gly and 1.0g / kg Gly and equimolar Ala, blood, liver and muscle samples were collected after 0.5 h and 1 h. The expression of IGF-1 and IGFBPs was detected by quantitative PCR. Western blot was used to analyze the relationship between JAK2 / STAT5 and IGF-I receptor (ERK / Akt / m TOR) changes. The results showed that different concentrations of Gly increased the protein and mRNA expression of IGF-1 in HepG2 cells in a dose-dependent manner. 1.0 g / kg Gly significantly increased the serum IGF-1 and albumin levels in mice Increase IGF-1 and IGFBP-3mRNA in liver, and down-regulate IGFBP-1mRNA level. Both in vitro and in vivo experiments showed that Gly can effectively activate the JAK2 / STAT5 signaling pathway in hepatocytes and liver and increase the phosphorylation of IGF-I receptor signaling in gastrocnemius muscle. These studies suggest that glycine may directly increase the sensitivity of the growth hormone receptor signaling pathway of the liver, thereby promoting IGF-1 expression and secretion. The results provide experimental evidence for further revealing the molecular nutritional function and mechanism of glycine.