Gene expression patterns of the fibroblast growth factors and their receptors during myogenesis of rat satellite cells
Gene expression patterns of the fibroblast growth factors and their receptors during myogenesis of rat satellite cells
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DOI：
10.1177/002215540004800805
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发表时间：
2000-08-01
影响因子：
3.2
通讯作者：
Yablonka-Reuveni, Z
中科院分区：
文献类型：
--
作者：
Kästner, S;Elias, MC;Yablonka-Reuveni, Z
卫星细胞是生后肌肉中的肌原性前体细胞，位于肌纤维基底膜下方。我们以前表明，成纤维细胞生长因子2（FGF 2，碱性FGF）刺激更多的卫星细胞进入细胞周期，但不修改一个短暂的增殖期的整体时间表和快速过渡到分化状态的卫星细胞进行肌纤维分离肌纤维。在这项研究中，我们调查了是否其他成员的FGF家族可以维持增殖状态的卫星细胞在大鼠肌纤维培养。我们发现，FGF 1，FGF 4和FGF 6（以及肝细胞生长因子，HGF）增强卫星细胞增殖的程度与FGF 2相似，而FGF 5和FGF 7是无效的。没有生长因子阻止增殖期或延迟卫星细胞向分化肌细胞生成素（+）状态的转变。然而，FGF 6延缓了细胞从肌纤维培养物中常规发生的肌生成素（+）状态的快速退出。为了确定上述生长因子可能参与调节卫星细胞在体内，我们研究了它们的mRNA表达模式，在培养的大鼠肌纤维使用RT-PCR。除FGF 4外，所有生长因子的表达均得到证实。仅FGF 6在分离的肌纤维中以较高水平表达，而不在肌纤维周围的结缔组织细胞或从肌肉解离的卫星细胞中表达。通过Western印迹分析，我们还证明了骨骼肌组织中存在FGF 6蛋白。因此，我们的研究表明，肌纤维作为体内肌肉FGF 6的主要来源。我们还使用RT-PCR来分析肌纤维培养物中四种酪氨酸激酶FGF受体（FGFR 1-FGFR 4）和HGF受体（c-met）的表达模式。根据培养时间，检测到所有受体的表达，FGFR 2和FGFR 3仅以低水平表达。只有FGFR 4在肌纤维中以较高的水平表达，而在结缔组织细胞培养物中不表达。FGFR 4在卫星细胞中的表达水平也高于非肌源性细胞，当两个细胞群从肌肉组织中释放并通过Percoll密度离心分离时。FGF 6和FGFR 4的独特定位模式可能反映了FGF信号复合物的这些成员在成人骨骼肌肌发生过程中的特定作用。
Satellite cells are the myogenic precursors in postnatal muscle and are situated beneath the myofiber basement membrane. We previously showed that fibroblast growth factor 2 (FGF2, basic FGF) stimulates a greater number of satellite cells to enter the cell cycle but does not modify the overall schedule of a short proliferative phase and a rapid transition to the differentiated state as the satellite cells undergo myogenesis in isolated myofibers. In this study we investigated whether other members of the FGF family can maintain the proliferative state of the satellite cells in rat myofiber cultures. We show that FGF1, FGF4, and FGF6 (as well as hepatocyte growth factor, HGF) enhance satellite cell proliferation to a similar degree as that seen with FGF2, whereas FGF5 and FGF7 are ineffective. None of the growth factors prolongs the proliferative phase or delays the transition of the satellite cells to the differentiating, myogenin(+) state. However, FGF6 retards the rapid exit of the cells from the myogenin(+) state that routinely occurs in myofiber cultures. To determine which of the above growth factors might be involved in regulating satellite cells in vivo, we examined their mRNA expression patterns in cultured rat myofibers using RT-PCR. The expression of all growth factors, excluding FGF4, was confirmed. Only FGF6 was expressed at a higher level in the isolated myofibers and not in the connective tissue cells surrounding the myofibers or in satellite cells dissociated away from the muscle. By Western blot analysis, we also demonstrated the presence of FGF6 protein in the skeletal musle tissue. Our studies therefore suggest that the myofibers serve as the main source for the muscle FGF6 in vivo. We also used RT-PCR to analyze the expression patterns of the four tyrosine kinase FGF receptors (FGFR1-FGFR4) and of the HGF receptor (c-met) in the myofiber cultures. Depending on the time in culture, expression of all receptors was detected, with FGFR2 and FGFR3 expressed only at a low level. Only FGFR4 was expressed at a higher level in the myofibers but not the connective tissue cell cultures. FGFR4 was also expressed at a higher level in satellite cells compared to the nonmyogenic cells when the two cell populations were released from the muscle tissue and fractionated by Percoll density centrifugation. The unique localization patterns of FGF6 and FGFR4 may reflect specific roles for these members of the FGF signaling complex during myogenesis in adult skeletal muscle.