Department of Animal Science and Technology, Laboratory of Animal Fat Deposition and Muscle Development, College of Animal Science and Technology, Northwest A&F University, 22 Xinong Road, Yangling, Shaanxi Province 712100, People's Republic of China.
Mol Biol Rep. 2011 Mar;38(3):2043-9. doi: 10.1007/s11033-010-0328-3. Epub 2010 Sep 21.
The Wnt/β-catenin signaling pathway regulates cell proliferation and differentiation to determine cell fate during embryogenesis. Lithium chloride (LiCl) is known to activate canonical Wnt signaling by inhibiting glycogen synthetase kinase-3β and consequently stabilizing free cytosolic β-catenin. To understand the role of the Wnt/β-catenin pathway in the regulation of porcine myoblast differentiation, we studied the effects of LiCl on cultured porcine myoblasts and β-catenin expression. A supplementation of 25 mM LiCl induced myoblast differentiation into myotubes over 3 days of culture. By semi-quantitative RT-PCR analyses, levels of mRNA encoding MyoD, Myogenin, Myf5 and several Wnt-responsive genes in the cultured myoblast cells were significantly increased after LiCl treatment. Using Western blotting and immunofluorescence analysis, we found that the protein levels of β-catenin were consistently increased by LiCl. Meanwhile, phosphorylated GSK-3β at Ser9 levels were also increased as an indicator of GSK-3β inactivation. Additionally, the nuclear staining of endogenous β-catenin was also significantly increased in porcine myoblasts 48 h after LiCl treatment. These results provided additional evidence that Wnt/β-catenin is a significant pathway that regulates myogenic differentiation. An enhanced level of β-catenin plays a positive role in porcine myoblast differentiation.
Wnt/β-catenin 信号通路通过抑制糖原合酶激酶-3β（GSK-3β）从而稳定游离细胞质 β-catenin 来激活经典 Wnt 信号，在胚胎发生过程中调节细胞增殖和分化，以决定细胞命运。已知氯化锂（LiCl）通过抑制糖原合酶激酶-3β（GSK-3β）从而稳定游离细胞质 β-catenin 来激活经典 Wnt 信号。为了了解 Wnt/β-catenin 通路在猪成肌细胞分化中的调节作用，我们研究了 LiCl 对培养的猪成肌细胞和 β-catenin 表达的影响。在培养的 3 天中，25mM LiCl 的补充诱导成肌细胞分化为肌管。通过半定量 RT-PCR 分析，LiCl 处理后，培养的成肌细胞中编码 MyoD、Myogenin、Myf5 和几个 Wnt 反应基因的 mRNA 水平显著增加。通过 Western blot 和免疫荧光分析，我们发现 LiCl 可使 β-catenin 蛋白水平持续增加。同时，GSK-3β 在 Ser9 位点的磷酸化水平也升高，表明 GSK-3β 失活。此外，LiCl 处理 48 小时后，猪成肌细胞核内的内源性 β-catenin 染色也显著增加。这些结果提供了额外的证据，表明 Wnt/β-catenin 是调节成肌分化的重要途径。β-catenin 水平的提高在猪成肌细胞分化中发挥积极作用。
