Pröls F, Ehehalt F, Rodriguez-Niedenführ M, He L, Huang R, Christ B
Institute of Anatomy and Cell Biology II, University of Freiburg, D-79001 Freiburg, Germany.
Dev Biol. 2004 Nov 15;275(2):315-24. doi: 10.1016/j.ydbio.2004.08.003.
The scapula is subdivided into head, collum, and blade. Due to the expression pattern of Emx2 and the absence of the scapula blade in Emx2 knockout mice, it has been suggested that Emx2 is involved in the formation of the scapula. Micromanipulation experiments revealed that ectoderm ablation over the somites does not affect Emx2 expression but inhibits the formation of the scapula blade indicating that Emx2 is not sufficient to induce scapula blade formation. Furthermore, we show that the formation of the scapula head is dependent, scapula blade formation independent of FGFR-1-mediated signaling. Overexpression of Emx2 does not influence scapula blade formation but leads to the development of an additional posterior digit in the anterior border of the limb. Taken together, the data presented implicate that Emx2 expression is necessary but not sufficient for the development of the scapula blade. It is not a marker for scapula development but rather provides positional information along the proximodistal and anterior-posterior limb axes, whereas the specificity of the developing skeletal elements is determined by the concerted interaction of Emx2 with other factors.
肩胛骨可分为头、颈和肩胛。由于Emx2的表达模式以及Emx2基因敲除小鼠中肩胛骨的缺失，有人提出Emx2参与肩胛骨的形成。显微操作实验表明，体节上方的外胚层消融并不影响Emx2的表达，但会抑制肩胛骨的形成，这表明Emx2不足以诱导肩胛骨的形成。此外，我们发现肩胛骨头部的形成依赖于FGFR-1介导的信号通路，而肩胛骨的形成则与之无关。Emx2的过表达并不影响肩胛骨的形成，但会导致肢体前缘额外长出一个后指。综上所述，所呈现的数据表明，Emx2的表达对于肩胛骨的形成是必要的，但并不充分。它不是肩胛骨发育的标志物，而是沿着肢体的近远轴和前后轴提供位置信息，而发育中骨骼元素的特异性则由Emx2与其他因素的协同相互作用决定。
