Uchiyama K, Ishikawa A, Hanaoka K
Molecular Embryology, Department of Biosciences, School of Science, Kitasato University, Kanagawa, 228-8555, Japan.
J Exp Zool. 2000 Feb 15;286(3):270-9.
Somites are the source of hypaxial musculature including skeletal muscles of the limb, tongue, and trunk. To get insight into the function of mouse Lbx1 homeobox gene in early somitic mesoderm differentiation, in situ hybridization analyses were performed. At the 4-6 somite stage (8 dpc), Lbx1 was first expressed in the lateral portion of the epithelial somite and dermomyotomal epithelium. This was in contrast to the expression of myf-5 in the medial region of the somite. The lateral expression of Lbx1 in somitic mesoderm then occurred regionally along the anterior-posterior body axis. Later, at 10 dpc (stage 1 of limb bud development), Lbx1-positive migrating cells originated in the lateral dermomyotomal lips at occipital, forelimb, and hindlimb levels. They also expressed Pax-3 and c-met, known as markers of the migrating limb muscle precursor cells. In stage 4 hindlimb bud (11.5 dpc), the dorsal and ventral muscle precursor populations expressed Lbx1. In stage 8 forelimb buds (12.5 dpc), Lbx1 expression was reduced in the proximal muscle masses, where the high expression of myogenin accompanying muscle differentiation was detected. These results suggest that mouse Lbx1 might be involved in the commitment or determination of a muscle cell subpopulation during hypaxial musculature development. J. Exp. Zool. 286:270-279, 2000.
体节是轴下肌的来源，包括肢体、舌头和躯干的骨骼肌。为深入了解小鼠Lbx1同源框基因在早期体节中胚层分化中的功能，进行了原位杂交分析。在4-6体节期（胚胎发育第8天），Lbx1首先在上皮性体节和生皮节肌上皮的外侧部分表达。这与myf-5在体节内侧区域的表达形成对比。然后，体节中胚层中Lbx1的外侧表达沿前后体轴呈区域性分布。后来，在胚胎发育第10天（肢芽发育第1阶段），Lbx1阳性迁移细胞起源于枕部、前肢和后肢水平的外侧生皮节唇。它们还表达Pax-3和c-met，这两种蛋白是迁移的肢体肌肉前体细胞的标志物。在胚胎发育第11.5天的后肢芽第4阶段，背侧和腹侧肌肉前体细胞群表达Lbx1。在胚胎发育第12.5天的前肢芽第8阶段，近端肌肉团中Lbx1的表达减少，在该区域检测到伴随肌肉分化的肌细胞生成素的高表达。这些结果表明，小鼠Lbx1可能在轴下肌发育过程中参与肌肉细胞亚群的定向或决定。《实验动物学杂志》286:270-279，2000年。
