LIGAND/RECEPTOR INTERACTIONS IN THE TGF BETA SUPERFAMILY

描述：转化生长因子-β是一种多功能的 控制细胞外关键成分产生的细胞因子 基质和内皮细胞生长抑制因子的作用 通过对细胞周期起负面作用来影响细胞。转化生长因子-β信号转导途径 两个单程跨膜受体，称为转化生长因子-βI型和类型 II受体，以及一系列细胞内效应器，称为Smads。 在这个系统中，信号是通过组装异四聚体来启动的 由生长因子配体和两个拷贝组成的信号复合体 I型和II型受体。目前，完全缺乏 关于受体本身和细节的结构信息 它们与这类重要的生长因子之间的联系。相当可观 理解调节增长的相互作用是有实际好处的 因子-受体组装，因为转化生长因子-β信号受到严格控制，并且 通过过度表达转化生长因子-β或突变来破坏这种平衡 它们自然地出现在受体或SMAD蛋白中，已被证明 与许多病理生理状态有关，包括纤维化 疾病和癌症。此外，转化生长因子-β及其信号受体是 高度保守的生长因子和生长因子大家族的原型 因子受体，称为转化生长因子-β超家族。这些因素中的许多因素都在发挥作用 在发育和细胞动态平衡中的关键作用，但目前 关于分子决定因素的信息很少 主宰配体-受体的专一性。这项提议的主要目标是 使用直接的基于结构的方法来提供明确的信息 关于氨基酸序列和空间决定因素 异四聚体中的配体-受体和受体-受体相互作用 转化生长因子-β信号复合体。在实验上，这一目标将会实现。 通过使用溶液核磁共振技术a)解决配体的结构 两种受体类型的结合域和b)以描述决定因素 控制受体-配体和受体-受体关联的特异性。 欣克博士计划用于这些研究的模型系统是孤立的 人转化生长因子-βI型和II型受体的配基结合域。 多核溶液核磁共振技术非常适合于这方面的研究。 问题是由于可溶性受体I型相对较小 11.1 kDa、II型14.1 kDa，以及最近发展起来的大肠杆菌表达系统。 为实现这一目标而进行的初步实验工作将集中在 可溶性II型受体及其结合部位的鉴定。在.期间 在项目的最后阶段，欣克博士计划解决 可溶性I型受体及其与II型受体的相互作用 受体和转化生长因子-β。出现的受体组装的一般原则 从这些研究中将a)为开始预测提供一个框架 跨转化生长因子-β超家族的配体-受体特异性和b)将使 干预转化生长因子-β信号通路的合理途径。

DESCRIPTION: Transforming growth factor beta (TGF-beta) is a multifunctional cytokine which controls the production of key components of the extracellular matrix and functions as a potent growth inhibitor of epithelial and endothelial cells by acting negatively on the cell cycle. TGF-beta signaling is mediated by two single pass transmembrane receptors, known as the TGF-beta type I and type II receptors, and a family of intracellular effectors, known as SMADS. Signaling in this system is initiated by assembly of a heterotetrameric signaling complex consisting of growth factor ligand and two copies each of the type I and type II receptors. At present, there is a complete lack of structural information regarding both the receptors themselves and the details of their association with this important class of growth factors. Considerable practical benefits exist in understanding the interactions which mediate growth factor-receptor assembly since TGF-beta signaling is tightly controlled, and disruption of this balance through overexpression of TGF-beta or mutations which occur naturally within the receptors or SMAD proteins has been shown to be linked to a number of pathophysiological states, including fibrotic disorders and cancer. Additionally, TGF-beta and its signaling receptors are the prototype for a large family of highly conserved growth factors and growth factor receptors, known as the TGF-beta superfamily. Many of these factors play critical roles in development and in cellular homeostasis, yet at present little information is available regarding the molecular determinants which govern ligand-receptor specificity. The primary objective of this proposal is to use a direct structure-based approach to provide definitive information regarding amino acid sequence and spatial determinants which govern ligand-receptor and receptor-receptor interactions in the heterotetrameric TGF-beta signaling complex. Experimentally, this objective will be accomplished by using solution NMR techniques to a) solve the structures of the ligand binding domains of the two receptor types and b) to delineate the determinants of specificity which govern receptor-ligand and receptor-receptor association. The model system that Dr. Hinck plans to use for these studies is the isolated ligand binding domains of the human TGF-beta type I and type II receptors. Multinuclear solution NMR techniques are ideally suited for studying this problem owing to the relatively small size of the soluble receptors, type I 11.1 kDa, type II 14.1 kDa, and recently developed E. coli expression systems. Initial experimental efforts at achieving this objective will focus on the soluble type II receptor and identification of its binding site. During the final period of the project, Dr. Hinck plans to solve the solution structure of the soluble type I receptor and to investigate its interaction with the type II receptor and TGF-beta. The general principles of receptor assembly which emerge from these studies will a) provide a framework for beginning to predict ligand-receptor specificity across the TGF-beta superfamily and b) will enable a rational approach toward intervening in the TGF-beta signaling pathway.