高表达FoxO1抑制猪骨骼肌成肌细胞的分化

Over-expression of FoxO1 inhibits the differentiation of porcine skeletal muscle myoblast

摘要:

FoxO1 (Forkhead box O1) 是调控肌肉生长、代谢和细胞分化的重要转录因子，但其在成肌细胞分化中的作用还不甚清楚。为了研究FoxO1对哺乳动物成肌细胞分化的影响，以原代培养的长白仔猪成肌细胞作为实验材料，用2％马血清诱导分化，采用实时荧光定量PCR、Western blotting和脂质体转染等方法检测FoxO1及早期和晚期生肌调节因子MyoD和myogenin在猪成肌细胞分化过程中的表达变化。结果显示，在猪成肌细胞分化过程中，FoxO1 mRNA表达量显著增加，但总蛋白量变化不显著，其磷酸化水平显著上调。同时，高表达FoxO1的猪成肌细胞中，生肌调节因子MyoD和myogenin mRNA表达受到显著抑制，而MyoD蛋白变化不显著，myogenin却显著下调 (P＜0.05)。以上结果表明，FoxO1能够推迟猪成肌细胞的分化时间并抑制分化；同时推测，FoxO1可能通过抑制生肌调节因子的表达控制骨骼肌纤维类型的终末分化。

Abstract:

The Forkhead box O1 (FoxO1) transcription factor governs muscle growth, metabolism and cell differentiation. However, its role in myoblast differentiation is unclear. To study the biological function of FoxO1 during differentiation in porcine primary myoblast, we constructed stably FoxO1 over-expressed porcine myoblast mediated by liposome and adopted morphological observation, quantitative real-time RT-PCR and Western blotting methods to analyze FoxO1 and early and late myogenic regulation factors MyoD and myogenin expression. During differentiation the mRNA level of FoxO1 was significantly increased. However, the total protein did not change but the phosphorylation of FoxO1 was upregulated. Furthermore, overexpression of FoxO1 in porcine myoblast decreased MyoD and myogenin mRNA, whereas MyoD protein changed little and myogenin was significantly suppressed (P<0.05). These results indicated that FoxO1 delays and negatively regulates the porcine myoblast differentiation. Moreover, FoxO1 may play a critical role in muscle fiber-type specification through the inhibition of myogenic regulation factors.