HIF-1α对颏舌肌发育和肌纤维类型的影响

Effect of HIF-1α on muscle fiber differentiation in mice

关键词:  低氧诱导因子-1α  条件性基因敲除  骨骼肌纤维  小鼠

Key words:  HIF-1α  conditional gene knock-out mice  skeletal muscle fiber  mice

摘要:

目的 研究低氧诱导因子-1α(hypoxia-inducible factor-1α, HIF-1α)对骨骼肌发育及肌纤维分型的影响。方法 将HIF^flox/- 转基因小鼠和骨骼肌环化重组酶(muscle creatine kinase-cyclization recombination enzyme, MCK-Cre)转基因小鼠交配,子代中获得HIF^flox/- Cre⁺小鼠互交,得到骨骼肌HIF-1α条件性敲降的HIFflox/floxCre⁺基因型小鼠(C₅₇BL/6J),取新生小鼠尾尖与骨骼肌组织鉴定基因型及敲降效率。随机选取HIF-1α敲降小鼠(KO)和野生型小鼠(WT)各10只,取颏舌肌组织总RNA,使用荧光定量PCR检测4种肌纤维类型(Ⅰ、Ⅱa、Ⅱb、Ⅱx)在不同基因型小鼠骨骼肌中的表达差异。结果 HIF-1α在基因敲除小鼠(KO)的骨骼肌中的表达量较野生型小鼠(WT)有明显降低(P<0.05)。相对于野生型小鼠(WT),基因敲除小鼠(KO)颏舌肌的Ⅰ、Ⅱa、Ⅱx型肌纤维表达量有降低趋势,而Ⅱb型纤维表达量有升高趋势。结论 Cre-loxP系统成功构建骨骼肌特异性敲除HIF-1α的转基因小鼠模型。HIF-1α在成肌分化过程中能够促进肌纤维Ⅰ、Ⅱa、Ⅱx分化,抑制Ⅱb纤维分化。

Abstract:

Objective To investigate the biological effects of hypoxia-inducible factor-1α (HIF-1α) on skeletal muscle differentiation with conditional knockout mice. Methods HIFflox/floxCre⁺ gene type were obtained by inbreeding HIFflox/- transgenic mice and muscle creatine kinase-cyclization recombination enzyme(MCK-Cre) transgenic mice. The expression of HIF-1α in skeletal muscle was identified by Real-Time PCR methods. Ten mice were randomly selected from each group of the mice named KO and WT. The expressions of muscle fiber type Ⅰ,Ⅱa,Ⅱb andⅡx were detected by real-time PCR. Results Compared with WT mice, the expression of HIF-1α in KO mice was significantly reduced (P＜0.05). In KO mice, there was a slight decrease inⅠ,Ⅱa,Ⅱx fiber types but an increase inⅡb fiber type. Conclusion The HIF-1α conditional knockout mice model has been successfully established from Cre-loxP system. HIF-1α can enhance typesⅠ, Ⅱa and Ⅱx fiber generation during the process of myogenic differentiation and suppresse Ⅱb fiber generation.