Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
Annu Rev Cell Dev Biol. 2011;27:377-407. doi: 10.1146/annurev-cellbio-092910-154148. Epub 2011 Jul 29.
Morphogens are long-range signaling molecules that pattern developing tissues in a concentration-dependent manner. The graded activity of morphogens within tissues exposes cells to different signal levels and leads to region-specific transcriptional responses and cell fates. In its simplest incarnation, a morphogen signal forms a gradient by diffusion from a local source and clearance in surrounding tissues. Responding cells often transduce morphogen levels in a linear fashion, which results in the graded activation of transcriptional effectors. The concentration-dependent expression of morphogen target genes is achieved by their different binding affinities for transcriptional effectors as well as inputs from other transcriptional regulators. Morphogen distribution and interpretation are the result of complex interactions between the morphogen and responding tissues. The response to a morphogen is dependent not simply on morphogen concentration but also on the duration of morphogen exposure and the state of the target cells. In this review, we describe the morphogen concept and discuss the mechanisms that underlie the generation, modulation, and interpretation of morphogen gradients.
形态发生素是长距离信号分子，以浓度依赖的方式对发育中的组织进行模式化。形态发生素在组织内的分级活性使细胞暴露于不同的信号水平，并导致特定区域的转录反应和细胞命运。在最简单的形式中，形态发生素信号通过从局部来源扩散和周围组织清除来形成梯度。反应细胞通常以线性方式转导形态发生素水平，这导致转录效应物的分级激活。形态发生素靶基因的浓度依赖性表达是通过它们与转录效应物的不同结合亲和力以及来自其他转录调节剂的输入来实现的。形态发生素的分布和解释是形态发生素与反应组织之间复杂相互作用的结果。对形态发生素的反应不仅取决于形态发生素的浓度，还取决于形态发生素暴露的持续时间和靶细胞的状态。在这篇综述中，我们描述了形态发生素的概念，并讨论了产生、调节和解释形态发生素梯度的机制。
