Murato Yasuhito, Hashimoto Chikara
Department of Biology, Graduate School of Science, Osaka University, Machikaneyama, Toyonaka, Osaka, Japan.
Dev Dyn. 2009 Sep;238(9):2179-92. doi: 10.1002/dvdy.21883.
Lens of vertebrate eyes is derived from competent pre-placodal ectoderm in response to signal(s) from retinal lineage. We herein report that the Xenopus Hes gene Xhairy2, which is expressed in pre-placodal ectoderm, is required for lens development from the initial stage. We show that Xhairy2 knockdown reduced the expression of lens marker genes at every step of lens determination, eventually resulting in ocular lens malformation. Interestingly, retina marker gene expression and retinal anlage morphology remained normal upon Xhairy2 knockdown. Furthermore, loss of lens field caused by Xhairy2 depletion was partially rescued by simultaneous knockdown of the cell cycle inhibitor gene p27(xic1). These results suggest that Xhairy2 is required for lens development through the regulation of p27(xic1) expression, independent of the known cascade of transcription factors. Based on these findings, we propose that Xhairy2 may maintain an intracellular environment in which inducing signal(s) can be accepted.
脊椎动物眼睛的晶状体源自具有感应能力的前板层外胚层，以响应来自视网膜谱系的信号。我们在此报告，非洲爪蟾的Hes基因Xhairy2在前板层外胚层中表达，从初始阶段起就对晶状体发育是必需的。我们表明，敲低Xhairy2会在晶状体决定的每个步骤中降低晶状体标记基因的表达，最终导致眼晶状体畸形。有趣的是，敲低Xhairy2后，视网膜标记基因的表达和视网膜原基形态仍保持正常。此外，通过同时敲低细胞周期抑制剂基因p27(xic1)，部分挽救了由Xhairy2缺失导致的晶状体区域丧失。这些结果表明，Xhairy2通过调节p27(xic1)的表达对晶状体发育是必需的，这独立于已知的转录因子级联反应。基于这些发现，我们提出Xhairy2可能维持一种能够接受诱导信号的细胞内环境。
