Regulation of Wnt Gradient Formation by Palmitoylation

项目概述：在胚胎和成人中，细胞命运的规范往往是由形态发生指导的。 信号蛋白领域，如Wnt蛋白。靶组织中的细胞产生浓度依赖性 反应，导致产生不同的细胞命运。因此，形态发生梯度预示着 细胞命运特化和分化的模式。信号蛋白离开位点的运动 是形成梯度的关键。最具特征的脊椎动物Wnt梯度之一是 在鸡的神经管中，Wnt-1/3a的背腹梯度调节了 增殖和分化。最近发现Wnt蛋白的翻译后修饰 与棕榈酸调节他们的活动和分布揭示了一个差距的理解， 这一过程的机械基础。本提案的目的是通过以下方式确定机制： 该棕榈酰化调节Wnt蛋白的分布和活性。PI假设， 豪猪碱介导的棕榈酰化调节Wnt-1和Wnt-3a在鸡体内的活性和分布 通过促进它们组装成多聚体以及通过降低它们的稳定性和它们的 扩散远离合成位点。拟议研究的理由是， 这些过程是开发治疗策略所必需的， 合适的组织或抑制脂质修饰的信号向其靶组织的递送。第一 具体目标是，Burrus实验室将首先使用生化方法来识别和表征该酶 负责棕榈酰化Wnt蛋白。对于第二个具体目标，Burrus实验室将利用 生物化学和体内方法来确定棕榈酰化调节Wnt的机制 活动最后，Burrus实验室将结合使用传统成像、实时成像和功能成像。 分析以确定棕榈酰化调节Wnt蛋白分布的机制。 与公共卫生的相关性：“这些数据意义重大，因为它们将提供至关重要的知识 用于开发涉及组织工程或将Wnt配体递送至特定细胞的疗法， 靶细胞以及涉及抑制异常Wnt信号传导的疗法。一旦这些战略 开发，有希望将Wnt靶向干细胞，以产生和扩增干细胞。 健康组织，包括肌肉、软骨、神经元和造血细胞。的标识 棕榈酰化的上游调节物也将提供用于治疗癌症的潜在治疗靶点， 依赖于Wnt配体表达的失调来促进其进展，包括肉瘤、恶性肿瘤、 间皮瘤、结肠直肠癌和黑色素瘤。

Project Summary: In both embryos and adults, cell fate specification is often directed by morphogenetic fields of signaling proteins, such as Wnt proteins. Cells in target tissues produce concentration dependent responses, resulting in the generation of different cell fates. Thus, morphogenetic gradients prefigure patterns of cell fate specification and differentiation. The movement of signaling protein away from the site of synthesis is key to the formation of a gradient. One of the best-characterized vertebrate Wnt gradients is in the chick neural tube, where a dorsal to ventral gradient of Wnt-1/3a regulates the balance between proliferation and differentiation. The recent discovery that the post-translational modification of Wnt proteins with palmitate regulates their activity and distribution has revealed a gap in the understanding of the mechanistic underpinnings of this process. The objective of this proposal is to determine the mechanism by which palmitoylation regulates the distribution and activity of Wnt proteins. The PI hypothesizes that Porcupine-mediated palmitoylation regulates the activity and distribution of Wnt-1 and Wnt-3a in the chick neural tube by facilitating their assembly into multimers as well as by reducing their stability and their rate of diffusion away from the site of synthesis. The rationale for the proposed studies is that an understanding of these processes is required for the development of therapeutic strategies to deliver lipid-modified signals to appropriate tissues or to inhibit the delivery of lipid-modified signals to their target tissues. For the first specific aim, the Burrus lab will first use biochemical approaches to identify and characterize the enzyme that is responsible for palmitoylating Wnt proteins. For the second specific aim, The Burrus lab will utilize biochemical and in vivo approaches to determine the mechanism(s) by which palmitoylation regulates Wnt activity. Lastly, the Burrus lab will use a combination of conventional imaging, live imaging and functional analysis to define the mechanism(s) by which palmitoylation regulates the distribution of Wnt proteins. Relevance to Public Health: "These data are significant because they will provide knowledge that is critical for the development of therapies that involve tissue engineering or delivery of Wnt ligands to particular target cells as well as therapies that involve the inhibition of aberrant Wnt signaling. Once such strategies are developed, there is the promise of targeting Wnts to stem cells for the generation and expansion of healthy tissues, including muscle, cartilage, neurons, and hematopoietic cells. The identification of the upstream regulator of palmitoylation will also provide a potential therapeutic target for treating cancers that rely on the deregulation of Wnt ligand expression for their progression, including sarcoma, malignant mesothelioma, colorectal cancer, and melanoma.