Department of Brain Protection, Institute of Basic Medical Sciences, 27 Taiping Road, Beijing 100850, PR China.
Exp Physiol. 2012 Feb;97(2):257-64. doi: 10.1113/expphysiol.2011.061382. Epub 2011 Oct 14.
Oxygen conditions influence a variety of biological processes of cells, including alterations in cellular growth, survival and differentiation. However, there have been few studies on the effects of hypoxia on proliferation and differentiation of myoblasts. In this study, we observed the effects of hypoxia (3% O(2)) on myogenic differentiation of C2C12 myoblasts and sought a possible mechanism involved in the regulation of myogenic differentiation of myoblasts by hypoxia. The expression of myosin heavy chain was detected by immunocytochemistry staining and Western blot analysis. The expression of muscle regulatory transcription factors was examined by RT-PCR analysis and Western blot analysis. The activity of extracellular signal-regulated kinases (ERK1/2) was investigated by forced expression of mitogen-activated protein kinase kinase 1 (MEK1(E)) and using Western blot analysis. We found that hypoxia inhibited myogenic differentiation of myoblasts. The expression of muscle regulatory transcription factors was downregulated by hypoxia in C2C12 myoblasts. During the inhibition of myogenic differentiation by hypoxia, ERK1/2 activation was suppressed, and increasing ERK1/2 activity by forced expression of MEK1(E) could partly reverse the inhibition of myogenic differentiation by hypoxia. These results suggest that the ERK1/2-mitogen-activated protein kinase pathway might be a possible mechanism involved in the inhibition of myogenic differentiation by hypoxia.
氧气条件会影响细胞的多种生物学过程，包括细胞生长、存活和分化的改变。然而，关于低氧对成肌细胞增殖和分化的影响的研究甚少。在这项研究中，我们观察了低氧（3% O(2)）对 C2C12 成肌细胞成肌分化的影响，并寻求低氧调节成肌细胞成肌分化的可能机制。通过免疫细胞化学染色和 Western blot 分析检测肌球蛋白重链的表达。通过 RT-PCR 分析和 Western blot 分析检测肌肉调节转录因子的表达。通过强制表达丝裂原激活蛋白激酶激酶 1（MEK1(E)）并通过 Western blot 分析研究细胞外信号调节激酶（ERK1/2）的活性。我们发现低氧抑制成肌细胞的成肌分化。低氧可下调 C2C12 成肌细胞中肌肉调节转录因子的表达。在低氧抑制成肌分化过程中，ERK1/2 激活受到抑制，通过强制表达 MEK1(E)增加 ERK1/2 活性可部分逆转低氧对成肌分化的抑制。这些结果表明 ERK1/2-丝裂原激活蛋白激酶途径可能是低氧抑制成肌分化的一种可能机制。
