持续激活Fgf8对颌面部不同来源成肌细胞的差异性作用

Differential effects of Fgf8 on the myoblasts derived from different sources in the craniofacial region

目的:探究持续激活成纤维细胞生长因子8(Fgf8)对颌面部的舌肌(来源于枕部体节)和咬肌(来源于鳃弓中胚层)成肌细胞的影响及差异。方法:将肌源性调节因子5(Myf5)-Cre基因敲入小鼠与Rosa26R-Fgf8基因敲入小鼠交配,得到Myf5-Cre;Rosa26R-Fgf8小鼠模型(在肌源性祖细胞特异性持续激活Fgf8)。选取实验所需天数的小鼠胚胎,分别采用Masson染色法观察舌肌和咬肌组织形态,免疫组化染色观察舌肌和咬肌中成熟肌纤维标记物肌球蛋白(Myosin)和成肌决定因子(MyoD)水平以检测其分化程度,BrdU标记法检测细胞增殖水平。结果:Masson染色结果显示Myf5-Cre;Rosa26R-Fgf8小鼠舌肌排列紊乱,但咬肌无明显变化。免疫组化染色结果表明舌肌中Myosin表达的减少程度明显大于咬肌(P<0.05)。颏舌肌中MyoD表达的增长幅度明显大于咬肌(P<0.05),但舌内肌中MyoD的表达显著减少(P<0.05)。BrdU标记法检测结果表明颏舌肌成肌细胞增殖水平的增长幅度明显大于咬肌(P<0.05),但舌内肌无明显变化(P>0.05)。结论:持续激活Fgf8对体节来源的颏舌肌和鳃弓中胚层来源的咬肌成肌细胞的增殖和分化分别起到明显的促进和抑制作用,并且对于颏舌肌的调节作用显著大于咬肌。此外,持续激活Fgf8对体节来源的舌内肌成肌细胞的增殖无明显促进作用,但对其分化的抑制作用同样大于鳃弓中胚层来源的咬肌。

Objective:Aim to investigate the effect of Fgf8 activation on the tongue myoblasts(derived from the somite)and the masseter myoblasts(derived from the unsegmented paraxial mesoderm)in the craniofacial region.Methods:A mouse model(Myf5-cre;Rosa26R-Fgf8,RF8)that specifically activates Fgf8 in myogenic progenitor cells and a red-green dual-fluorescence mouse model called Myf5-cre;mTmG were used to obtain mouse embryos of different days that were soon processed.Masson staining was performed to observe the morphology of tongue and masseter muscle.Immunohistochemistry was used to detect the expression of Myosin and MyoD in the muscle.BrdU labeling assay was used to assess the cell proliferation.Results:Masson staining showed that Myf5-cre;Rosa26R-Fgf8 mice had disordered tongue muscle fibers,but no significant changes in masseter muscle.Immunohistochemical results showed that the reduction of Myosin in tongue muscle was significantly greater than that of masseter muscle(P<0.05).The increase of MyoD in the genioglossus muscle was significantly greater than that of the masseter muscle(P<0.05),but the expression of MyoD in the intrinsic tongue muscle decreased dramaticly(P<0.05).BrdU labeling assay showed that the growth rate of the proliferation of genioglossus myoblasts was significantly greater than that of masseter muscle(P<0.05),but there was no significant change in the intrinsic tongue muscle(P>0.05).Conclusions:Fgf8 activation significantly promotes the proliferation of genioglossus myoblasts derived from the somite and masseter myoblasts derived from the unsegmented paraxial mesoderm and inhibits their differentiation.Its regulating effect on the genioglossus muscle is significantly greater than that of the masseter muscle.In addition,Fgf8 activation did not promote the proliferation of somite-derived intrinsic tongue myoblasts,but its inhibitory effect on the differentiation was also greater than that of masseter myoblasts.