Dalrymple K R, Prigozy T I, Shuler C F
Center for Craniofacial Molecular Biology, School of Dentistry, University of Southern California, 2250 Alcazar, CSA 103, Los Angeles, CA 90033, USA.
Differentiation. 2000 Dec;66(4-5):218-26. doi: 10.1046/j.1432-0436.2000.660408.x.
Variable gene expression patterns have been shown to exist between embryonic, fetal, and neonatal lineages of limb skeletal myoblasts in vitro and in vivo. In this study, we examined the molecular phenotype of embryonic, fetal, and neonatal tongue myoblasts in primary culture for comparison with in vivo developmental tongue myoblasts. Myogenic regulatory factor (MRF) and myosin heavy chain (MHC) gene expression were determined in culture during both growth and differentiation conditions by PCR, immunoblotting, and immunohistochemistry. Unlike their in vivo tongue myoblast equivalents, developmental tongue myoblast cultures featured the expression of MyoD when kept in growth conditions. Differentiation conditions in vitro induced myogenic tongue lineages to maintain characteristics of their in vivo morphologic and contractile gene phenotype. Both in vivo and in vitro, embryonic tongue lineages predominantly expressed MHC-embryonic isoforms, while fetal and neonatal tongue lineages predominantly expressed fast and perinatal isoforms of contractile genes. A notable difference from the in vivo condition that was observed in differentiated tongue myotubes in vitro was the presence of the MHC-slow protein. It was previously demonstrated that MHC-slow protein was undetectable during the in vivo development of the tongue musculature despite the abundance of slow isoform transcripts. The present characterization of primary tongue myogenic cultures indicates that murine myoblast heterogeneity exists primarily between developmental lineages at the level of contractile gene expression. Outside their native surroundings, developmental myogenic tongue populations are unable to recapitulate the determination and differentiation molecular profiles that occur in vivo.
已表明肢体骨骼肌成肌细胞的胚胎、胎儿和新生儿谱系在体外和体内存在可变的基因表达模式。在本研究中，我们检测了原代培养的胚胎、胎儿和新生儿舌成肌细胞的分子表型，以便与体内发育中的舌成肌细胞进行比较。通过PCR、免疫印迹和免疫组织化学法，在生长和分化条件下的培养物中测定生肌调节因子（MRF）和肌球蛋白重链（MHC）基因的表达。与体内的舌成肌细胞不同，发育中的舌成肌细胞培养物在生长条件下具有MyoD的表达。体外分化条件诱导生肌舌谱系维持其体内形态学和收缩基因表型的特征。在体内和体外，胚胎舌谱系主要表达MHC胚胎亚型，而胎儿和新生儿舌谱系主要表达收缩基因的快速和围产期亚型。在体外分化的舌肌管中观察到的与体内情况的一个显著差异是存在MHC慢蛋白。先前已证明，尽管存在丰富的慢亚型转录本，但在舌肌组织的体内发育过程中无法检测到MHC慢蛋白。原代舌生肌培养物的目前特征表明，小鼠成肌细胞的异质性主要存在于发育谱系之间收缩基因表达水平上。在其天然环境之外，发育中的生肌舌群体无法重现体内发生的决定和分化分子谱。
