Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, USA.
Dev Dyn. 2010 Jun;239(6):1674-83. doi: 10.1002/dvdy.22302.
Sonic hedgehog (Shh) signaling plays important roles in the formation of the auditory epithelium. However, little is known about the detailed expression pattern of Shh and the cell sources from which Shh is secreted. By analyzing Shh(CreEGFP/+) mice, we found that Shh was first expressed in all cochlear spiral ganglion neurons by embryonic day 13.5, after which its expression gradually decreased from base to apex. By postnatal day 0, it was not detected in any spiral ganglion neurons. Genetic cell fate mapping results also confirmed that Shh was exclusively expressed in all spiral ganglion neurons and not in surrounding glia cells. The basal-to-apical wave of Shh decline strongly resembles that of hair cell differentiation, supporting the idea that Shh signaling inhibits hair cell differentiation. Furthermore, this Shh(CreEGFP/+) mouse is a useful Cre line in which to delete floxed genes specifically in spiral ganglion neurons of the developing cochlea.
声波刺猬（Shh）信号在听觉上皮的形成中发挥着重要作用。然而，关于 Shh 的详细表达模式以及分泌 Shh 的细胞来源知之甚少。通过分析 Shh(CreEGFP/+) 小鼠，我们发现 Shh 在胚胎第 13.5 天首先在所有耳蜗螺旋神经节神经元中表达，之后其表达从基底到顶点逐渐减少。到出生后第 0 天，在任何螺旋神经节神经元中都检测不到 Shh。遗传细胞命运图谱结果也证实 Shh 仅在所有螺旋神经节神经元中表达，而不在周围神经胶质细胞中表达。Shh 下降的基底到顶点波类似于毛细胞分化的波，支持 Shh 信号抑制毛细胞分化的观点。此外，这种 Shh(CreEGFP/+) 小鼠是一种有用的 Cre 系，可特异性删除发育中的耳蜗螺旋神经节神经元中的 floxed 基因。
