Umeå Centre for Molecular Medicine, Umeå University, Umeå, Sweden.
Dev Dyn. 2011 Aug;240(8):1917-28. doi: 10.1002/dvdy.22692.
Bone morphogenetic protein (BMP) signals are essential for lens development. However, the temporal requirement of BMP activity during early events of lens development has remained elusive. To investigate this question, we have used gain- and loss-of-function analyses in chick explant and intact embryo assays. Here, we show that BMP activity is both required and sufficient to induce L-Maf expression, whereas the onset of δ-crystallin and initial elongation of primary lens fibre cells are BMP-independent. Moreover, before lens placode formation and L-Maf onset, but not after, prospective lens placodal cells can switch to an olfactory placodal fate in response to decreased BMP activity. In addition, L-Maf is sufficient to up-regulate δ-crystallin independent of BMP signals. Taken together, these results show that before L-Maf induction BMP activity is required for lens specification, whereas after L-Maf up-regulation, the early differentiation of primary lens fibre cells occurs independent of BMP signals.
骨形态发生蛋白 (BMP) 信号对于晶状体发育是必不可少的。然而，BMP 活性在晶状体发育早期事件中的时间要求仍然难以捉摸。为了研究这个问题，我们在鸡胚外植体和完整胚胎分析中使用了增益和失能分析。在这里，我们表明 BMP 活性既需要又足以诱导 L-Maf 表达，而 δ-晶状体蛋白和初级晶状体纤维细胞的初始伸长则与 BMP 无关。此外，在晶状体基板形成和 L-Maf 开始之前，但不在之后，潜在的晶状体基板细胞可以响应 BMP 活性的降低而转变为嗅觉基板命运。此外，L-Maf 足以独立于 BMP 信号上调 δ-晶状体蛋白。总之，这些结果表明，在 L-Maf 诱导之前，BMP 活性对于晶状体的特化是必需的，而在 L-Maf 上调之后，初级晶状体纤维细胞的早期分化独立于 BMP 信号发生。
