Using Glycodendrimers to Elucidate the Importance of Multivalency in the Structures and Functions of Galectins

凭借这一奖项，化学部的生命过程化学项目资助蒙大拿州立大学的Mary Cloninger教授开发糖修饰的高支化化合物，以研究聚集素在细胞间相互作用中的重要作用。半乳糖凝集素是一种碳水化合物结合蛋白，参与许多生理功能，包括细胞如何与其他细胞相互作用和交流，并与纤维化、癌症和心脏病等疾病有关。一组高度分支的分子，称为糖树状聚合物，其表面显示不同数量的糖。这些糖树状大分子将用于生化、结构和细胞生物学研究，以研究碳水化合物结合对凝集素相互作用的影响，以及这些蛋白质相互作用如何影响细胞间相互作用。在这个项目下，PI将接触到来自不同群体的学生，通过与Flathead Valley社区学院（FVCC）和当地高中的外展项目，将这些学生纳入Cloninger的研究小组。此外，Cloninger博士和她的本科生和研究生将在四所当地高中的化学课上展示他们的研究，并为感兴趣的高中生提供在蒙大拿州立大学进行显微镜实验的机会。尽管凝集素通过与细胞表面碳水化合物的结合相互作用在细胞识别过程中起着关键作用，但其多价和单价功能之间相互作用的调节尚不清楚。此外，目前尚不清楚三个亚科的凝集素是否具有协同作用或不同的功能。拟议的研究将使用糖树状大分子来更好地了解凝集素的结构-功能关系。乳糖功能化的糖树大分子是研究多价糖-凝集素相互作用的理想大分子，因为它们的大小和碳水化合物端基的数量都可以系统地改变。因此，糖树状大分子将用于鉴定n端结构域在指导多价半乳糖凝集素-3/碳水化合物相互作用中的作用。此外，糖树状大分子将用于评估来自三个亚家族的凝集素是否协同工作，以在其多价相互作用中实现更高的特异性和选择性。动态光散射，透射电子显微镜和荧光显微镜将用于可视化糖树状聚合物-凝集素相互作用。此外，将进行细胞摄取和细胞聚集试验，使用一系列结合半乳糖凝集素-3和半乳糖凝集素混合物的糖树状聚合物。阐明在复杂环境中指导多价相互作用的关键原则对于理解细胞表面碳水化合物和凝集素之间多价关联的作用至关重要。在这方面，碳水化合物功能化的树状大分子为系统研究多价相互作用在碳水化合物-凝集素结合中的作用提供了理想的平台。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

With this award, the Chemistry of Life Processes Program in the Chemistry Division is funding Professor Mary Cloninger from Montana State University to develop sugar-modified highly branched compounds to study the important roles that galectins play in cell-to-cell interactions. Galectins are carbohydrate binding proteins involved in many physiological functions that involve how cells interact and communicate with other cells and are linked to diseases such as fibrosis, cancer and heart disease. A set of highly branched molecules, called glycodendrimers, with varied numbers of sugars displayed on their surfaces will be synthesized. These glycodendrimers will be used in biochemical, structural, and cell biological studies to investigate the effects that carbohydrate binding has on how galectins interact with each other and how these protein interactions affect cell-to-cell interactions. Under this project, the PI will reach out to students from diverse populations to bring these students into the Cloninger research group through outreach programs with Flathead Valley Community College (FVCC) and local high schools. In addition, Dr. Cloninger and her undergraduate and graduate students will present their research to chemistry classes at four local high schools and give interested high school students opportunities to perform microscopy experiments at Montana State University.Although galectins play a critical role in cellular recognition processes through their binding interactions with cell surface carbohydrates, modulation of the interplay between their multivalent and monovalent functionalities is not well understood. Moreover, whether galectins from the three subfamilies have synergistic or distinct functions is currently unknown. The proposed research will use glycodendrimers to better understand galectin structure-function relationships. Lactose-functionalized glycodendrimers are ideal macromolecules with which to study multivalent carbohydrate-lectin interactions because both their size and the number of carbohydrate end groups can be systematically varied. Thus, glycodendrimers will be used to identify the role of the N-terminal domain in directing multivalent galectin-3/carbohydrate interactions. In addition, glycodendrimers will be used to evaluate whether galectins from the three subfamilies are working in concert to achieve increased specificity and selectivity in their multivalent interactions. Dynamic light scattering, transmission electron microscopy and fluorescence microscopy will be employed to visualize glycodendrimer-lectin interactions. In addition, cellular uptake, and cellular aggregation assays using a series of glycodendrimers binding to galectin-3 and to mixtures of galectins will be performed. Elucidating the key principles that guide multivalent interactions in complex environments is essential for understanding the role of multivalent associations between cell surface carbohydrates and galectins. In this regard, carbohydrate-functionalized dendrimers provide an ideal platform for the requisite systematic study of the role of multivalent interactions in carbohydrate-lectin binding.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.