Structural Determination of the E-Related Region of the TGFbeta type III receptor

描述(申请人提供)：转化生长因子β(转化生长因子？)超家族由42个结构相关的多肽生长因子组成，在人类中发挥不同的功能。TGF3超家族的所有成员都通过一组不同的细胞外受体发出信号，通常被称为I型和II型受体。该超家族的原型成员是转化生长因子S：TGFb1、2和3。当配体与II型受体结合时，信号被启动，随后I型受体招募形成成熟的信号复合体。转化生长因子β1和转化生长因子3都与II型受体(T？RII)有很高的亲和力，并能够在没有任何辅助的情况下启动信号转导。另一方面，转化生长因子-2与II型受体结合很弱。转化生长因子？2与TBRII的结合亲和力本来就很低，但通过使用辅助受体β-聚糖来补偿。β-聚糖在转化生长因子β2信号转导中的作用是通过形成转化生长因子β2：β-聚糖：TBRII三元复合体，增加转化生长因子β2与T(3RII)的低亲和力，从而将转化生长因子β2递送给T？RII。转化生长因子？I型受体(T？RI)被募集到复合体中，β-聚糖被取代，形成成熟的信号复合体。虽然已经知道β-聚糖是转化生长因子β-2信号转导所必需的，但复杂的组装机制尚不清楚。Betaglycan的胞外结构域由两个独立的亚结构域组成，每个亚结构域都能够促进转化生长因子(3)诱导的rSMAD磷酸化。这意味着胞外区的每一半都可以独立地向T？rII递送转化生长因子-2。膜-远端部分称为内源性相关区域(BGE)，膜-近端部分称为尿调蛋白相关区域(BGU)。虽然这两个区域都能结合TGFb，但BGU也能结合抑制素。结合抑制素结合仅限于BGU的事实，这也意味着每一半可能在转化生长因子3信号转导中发挥不同的作用。BGE被选为研究对象，因为它是唯一能够促进转化生长因子-2信号转导的分子。为了进一步了解Betaglycan的呈递机制，我们将利用溶液核磁共振技术测定Betaglycan内切相关区域(BGE)的溶液结构，BGE与TGFB2和T？RII形成的络合物具有互补的晶体结构。同时，天然凝胶位移分析和表面等离子体共振结合研究将被用来研究BGE对T？RII结合的影响。已发现转化生长因子-2在牙齿发育中起关键作用，也与牙源性肿瘤的发生有关，转化生长因子？2基因敲除的小鼠会发生腭裂。了解β-葡聚糖在转化生长因子(32)信号转导中的结构和功能作用，将对颅面发育有重要的意义。

DESCRIPTION (provided by applicant): The transforming growth factor beta (TGF?) superfamily is composed of 42 structurally related polypeptide growth factors that perform various functions in humans. All of the members of the TGF3 superfamily signal through a distinct set of extracellular receptors commonly known as the type I and type II receptors. The prototypic members of the superfamily are the TGF?s: TGFB?1, 2, and 3. Signaling is initiated when the igand binds to the type II receptor with subsequent recruitment of the type I receptor forming the mature signaling complex. Both TGF?1 and 3 have intrinsically high affinity for the type II receptor (T?RII) and are able to initiate signaling without any assistance. TGF?2, on the other hand, binds very weakly to the type II receptor. The intrinsically low binding affinity of TGF?2 for TBRII is compensated through the use of an accessory receptor, betaglycan. Betaglycan's role in TGF?2 signaling is to present TGF?2 to T?RII by increasing the intrinsically low affinity of TGF?2 for T(3RII through the formation of a TGF?2:betaglycan:TBRII ternary complex. The TGF? type I receptor (T?RI) is recruited to the complex, betaglycan is displaced, forming the mature signaling complex. Although it is known that betaglycan is required for TGF?2 signaling, the mechanism of complex assembly is not. Betaglycan's extracellular domain is composed of two separate sub-domains, each capable of promoting TGF(3 induced rSMAD phosphorylation. Implying that each half of the extracellular domain betaglycan can independently present TGF?2 to T?RII. The membrane-distal half is referred to as the endoglin-related region (BGE) and the membrane-proximal half is referred to as uromodulin-related region (BGU). While both regions are able to bind TGFB, BGU is also capable of binding inhibin. In combination with the fact that inhibin binding is solely restricted to BGU, it also implies that each half may play a different role in TGF 3 signaling. BGE was selected for study since it is solely capable promoting TGF?2 signaling. To further our understanding of betaglycan's mechanism of presentation, the solution structure of the Endoglin-related region of betaglycan (BGE) will be determined using solution NMR spectroscopy with the complementing crystal structure of BGE in complex with TGFB2 and T?RII. In parallel, native gel shift assays and surface plasmon resonance binding studies will be used to examine the influence BGE has on the binding of T?RII. TGF?2 has been found to play crucial roles in tooth development, it has also been implicated in tumorigenesis of odontogenic neoplasms, and TGF?2 knockout mice develop cleft palate. Understanding the structural and functional role betaglycan plays in TGF(32 signaling, it will give vital insight into craniofacial development.