Kosman D, Ip Y T, Levine M, Arora K
Biology Department, University of California, San Diego, La Jolla 92093.
Science. 1991 Oct 4;254(5028):118-22. doi: 10.1126/science.1925551.
A gradient of the maternal morphogen dorsal establishes asymmetric patterns of gene expression along the dorsal-ventral axis of early embryos and activates the regulatory genes twist and snail, which are responsible for the differentiation of the ventral mesoderm. Expression of snail is restricted to the presumptive mesoderm, and the sharp lateral limits of this expression help to define the mesoderm-neuroectoderm boundary by repressing the expression of regulatory genes that are responsible for the differentiation of the neuroectoderm. The snail gene encodes a zinc finger protein, and neuroectodermal genes that are normally restricted to ventral-lateral regions of early embryos are expressed throughout ventral regions of snail- mutants. The formation of the sharp snail border involves dosage-sensitive interactions between dorsal and twist, which encode regulatory proteins that are related to the mammalian transcription factors NF-kB and MyoD, respectively.
母体形态发生素背腹侧蛋白的浓度梯度沿着早期胚胎的背腹轴建立基因表达的不对称模式，并激活调控基因twist和snail，这两个基因负责腹侧中胚层的分化。snail的表达局限于预定中胚层，该表达的清晰外侧界限通过抑制负责神经外胚层分化的调控基因的表达，有助于界定中胚层-神经外胚层边界。snail基因编码一种锌指蛋白，通常局限于早期胚胎腹外侧区域的神经外胚层基因在snail突变体的整个腹侧区域均有表达。清晰的snail边界的形成涉及背腹侧蛋白和twist之间的剂量敏感相互作用，它们分别编码与哺乳动物转录因子NF-kB和MyoD相关的调控蛋白。
