Laboratory for Sensory Development, RIKEN Center for Developmental Biology, 2-2-3 Minatojima-Minamimachi, Chuo-ku, Kobe, Japan.
Dev Dyn. 2012 Nov;241(11):1716-28. doi: 10.1002/dvdy.23856. Epub 2012 Sep 25.
The inner ear and epibranchial ganglia of vertebrates arise from a shared progenitor domain that is induced by FGF signalling, the posterior placodal area (PPA), before being segregated by Wnt signalling. One of the first genes activated in the PPA is the transcription factor Pax2. Loss-of- and gain-of function studies have defined a role for Pax2 in placodal morphogenesis and later inner ear development, but have not addressed the role Pax2 plays during the formation and maintenance of the PPA.
To understand the role of Pax2 during the development of the PPA, we used over-expression and repression of Pax2. Both gave rise to a smaller otocyst and repressed the formation of epibranchial placodes. In addition, cell cycle analysis revealed that Pax2 suppression reduced proliferation of the PPA.
Our results suggest that Pax2 functions in the maintenance but not the induction of the PPA. One role of Pax2 is to maintain proper cell cycle proliferation in the PPA.
脊椎动物的内耳和脑颅神经节来源于一个由 FGF 信号诱导的共同前体细胞区域，即后脑板区域（PPA），然后通过 Wnt 信号将其分隔开。PPA 中最早激活的基因之一是转录因子 Pax2。缺失和获得功能研究已经确定了 Pax2 在脑板形态发生和后来内耳发育中的作用，但尚未解决 Pax2 在 PPA 的形成和维持中的作用。
为了了解 Pax2 在 PPA 发育过程中的作用，我们使用了 Pax2 的过表达和抑制。这两种方法都导致了较小的耳泡和抑制了脑颅神经节板的形成。此外，细胞周期分析显示 Pax2 的抑制减少了 PPA 的增殖。
我们的结果表明，Pax2 在 PPA 的维持而非诱导中发挥作用。Pax2 的一个作用是维持 PPA 中适当的细胞周期增殖。
