Shaping a Shh morphogen gradient

描述(由申请人提供)：Hedgehog(HH)信号蛋白家族的成员在协调细胞生长和分化方面发挥关键作用。许多胚胎组织和结构在发育过程中需要HH信号来形成，因此大量的出生缺陷与Shh信号的减少有关。最显著的畸形之一是全前脑畸形，这可能是由于Sonic hedgehog(Shh)信号的减少而导致的，这些方法包括Shh和其他途径成分的遗传突变、畸胎原暴露或胆固醇生物合成的先天错误。HH蛋白从局部来源分泌，并在邻近的一片细胞中引起不同的、浓度依赖的反应。HH蛋白生物发生的一个独特特征是产生一个成熟的信号结构域，该结构域被胆固醇和棕榈酰加合物共价修饰。鉴于形态原分布的重要性，我们感兴趣的是脂质修饰对Shh在发育中的神经管中空间分布的详细作用。为此，我们开发了一种可视化的Shh分子来表征包装、繁殖和接收具有独特生化特性的形态发生的细胞机制。我们还建议建立局部表达可光激活Shh-GFP的转基因斑马鱼品系，以测量每个加合物对Shh扩散和降解速度的贡献。

DESCRIPTION (provided by applicant): Members of the Hedgehog (Hh) family of signaling proteins play critical roles in coordinating cell growth and differentiation. Many embryonic tissues and structures require Hh signaling for their formation during development and thus a large number of birth defects have been associated with reduced Shh signaling. One of the more striking malformations is holoprosencephaly that may result from reduced Sonic hedgehog (Shh) signaling by a variety of means including genetic mutations in Shh and other pathway components, teratogen exposure, or inborn errors of cholesterol biosynthesis. Hh proteins are secreted from a localized source and elicit distinct, concentration-dependent responses in a field of neighboring cells. A unique feature of Hh protein biogenesis is the production of a mature signaling domain that is covalently modified by cholesteryl and palmitoyl adducts. Given the importance of morphogen distribution, we are interested in the detailed roles of the lipid modifications on the spatial deployment of Shh in the developing neural tube. Towards this end, we have developed a visualizable Shh molecule to characterize the cellular mechanisms that package, propagate and receive a morphogen with unique biochemical properties. We also propose to generate lines of transgenic zebrafish with localized expression of photoactivatible Shh-GFP to measure the contribution of each adduct on the rate of Shh diffusion and degradation.