Functional analysis of homeobox genes in neuromere development : Mouse molecular genetical approch

点击翻译按钮获取中文摘要

(1) Somites are the source of hypaxial musculature including skeletal muscles of the limb, tongue and the trunk. To get insight into the function of mouse Lbxl homeobox gene in the early somitic mesoderni differentiation, in situhybridization analyses was performed. At 4-6 somite stage (8dpc), Lbxl was first expressed in the lateral portion of the epithelial somite and of dermomyotomal epithelium. This was contrast to the expression of myf-5 in the medial region of the somite. Then the lateral expression of Lbxl in somitic mesoderm occurred regionally along the anterior-posterior body axis. Later at 10 dpc (stage 1 for limb bud development) Lbxl-positive migrating cells originated from the lateral dermomyotomal lips at occipital, forelimb and hindlinib 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 Lbxl. In stage 8 forelimb buds ( … More 12.5 dpc), Lbxl expression was reduced in the proximal muscle masses where the highly expression of myogenin accompanying the muscle differentiation was detected. These results suggest that mouse Lbxl might be involved in the commitment or determination of a muscle cell subpopulation during the hypaxial musculature development.(2) cHox11L2, the chick counterpart of mouse Hox11L2, was isolated. cHox11L2 was expressed in the developing chick peripheral nervous system, i. e. sensory cranial nerves of the placodal ectoderm origin, sympathetic ganglia, dorsal root ganglia and enteric ganglia as well as the limited population of the spinal cord. In neuronal derivatives of the neural crest, dHox11L2 was expressed in the postmigratory cells and not in the migrating neural crest cells. Furthermore, Intense signals of cHox11L2 mRNA were detected even in the spinal cord and the dorsal root of 10 day embryo. These results suggest that cHox11L2 might play a role in the determination and/or maintenance of neuronal differentiation during chick nervous system development. Less