Structure-Function Investigation of DAN-mediated BMP Antagonism

 描述（由申请人提供）：骨形态发生蛋白（BMP）是一种分泌型配体，在发育和组织稳态中发挥重要作用。因此，存在微调和调节其信号传导的机制。分泌的细胞外拮抗剂用于结合BMP配体并中和BMP信号传导。该建议将集中在DAN（差异筛选选择的基因畸变在神经母细胞瘤）家族的细胞外拮抗剂。DAN家族由七个成员组成，它们可以显示出不同的BMP拮抗效力。例如，Gremlin-2是一种有效的拮抗剂，而NBL 1的效力明显较低。不幸的是，DAN家族成员的异常上调与几种人类疾病的进展有关，包括慢性肾病（CKD）、肺纤维化和肺动脉高压。因此，DAN家族成员目前正在被治疗靶向。此外，最近的证据也指出，在胚胎干细胞（ES）的分化不同的角色。有趣的是，虽然Gremlin-2促进ES细胞分化为心房心肌细胞，但NBL 1支持神经表型。尽管如此，DAN家族成员如何螯合BMP配体的知识和对它们的结构差异的理解是缺乏的，这在很大程度上是由于缺乏对它们相互作用的结构洞察。我们的目标是解决DAN：BMP相互作用的分子复杂性。为了实现我们的目标，我们将追求以下三个具体目标：（1）确定Gremlin-2（有效的DAN家族拮抗剂）与BMP的分子相互作用，（2）结构表征NBL 1（不同的DAN家族成员）单独和与BMP复合，并确定BMP拮抗作用差异的基础和（3）在分子水平上描述Gremlin-2和NBL 1促进不同的ES细胞谱系。从这些研究中，我们期望得到一个更深入的了解DAN：BMP的相互作用，这将支持的治疗药物，靶向DAN拮抗剂的发展。我们还期望这些结果将揭示指导ES细胞分化的机制。我们的研究将对BMP信号传导领域产生深远的全面影响，因为它们将极大地扩展我们对BMP配体如何被DAN家族成员拮抗的理解。

 DESCRIPTION (provided by applicant): Bone Morphogenetic Proteins (BMPs) are secreted ligands that play important roles in development and tissue homeostasis. As such, mechanisms exist to fine-tune and regulate their signaling. Secreted extracellular antagonists function to bin BMP ligands and neutralize BMP signaling. This proposal will focus on the DAN (Differential screening-selected gene Aberrative in Neuroblastoma) family of extracellular antagonists. The DAN family consists of seven members, which can display different potencies for BMP antagonism. For example, Gremlin-2 is a potent antagonist, whereas NBL1 is significantly less potent. Unfortunately, aberrant upregulation of DAN family members is linked to the progression of several human diseases, including chronic kidney diseases (CKD), pulmonary fibrosis and pulmonary arterial hypertension. Thus, DAN family members are currently being targeted therapeutically. Furthermore, recent evidence has also pointed to divergent roles in the differentiation of embryonic stem (ES) cells. Interestingly, while Gremlin-2 promotes ES cell differentiation to atrial cardiomyocytes, NBL1 supports a neural phenotype. In spite of this, knowledge of how DAN family members sequester BMP ligands and an understanding of their structural differences is lacking, in large part due to the absence of structural insight into thei interactions. Our objective in this proposal is to resolve the molecular intricacies of DAN:BMP interactions. To achieve our objective we will pursue the following three specific aims: (1) Determine the molecular interactions of Gremlin-2, potent DAN family antagonist with BMP, (2) Structurally characterize NBL1, a divergent DAN family member, alone and in complex with BMP, and determine the basis for differences in BMP antagonism and (3) Describe at the molecular level how Gremlin-2 and NBL1 promote different ES cell lineages. From these studies we expect to derive a deeper understanding of DAN:BMP interactions which will support the development of therapeutics that target DAN antagonist. We also expect that these results will reveal insight into the mechanisms that guide ES cells differentiation. Our studies will have a profound overall impact on the field of BMP signaling, as they will greatly expand our understanding of how BMP ligands are antagonized by members of the DAN family.