Structure-Function Investigation of DAN-mediated BMP Antagonism

 描述(申请人提供)：骨形态发生蛋白(BMPs)是一种分泌型配体，在发育和组织动态平衡中发挥重要作用。因此，存在微调和调节它们的信号的机制。分泌的细胞外拮抗剂作用于结合BMP配体并中和BMP信号。这项建议将集中在DAN(差异筛选-神经母细胞瘤中的Aberrative基因)家族的细胞外拮抗剂上。丹氏家族由7名成员组成，可以表现出不同的BMP拮抗力。例如，Gremlin-2是一种强有力的拮抗剂，而NBL1的效力明显较弱。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，包括慢性肾脏疾病(CKD)、肺纤维化和肺动脉高压。因此，丹的家人目前正成为治疗的目标。此外，最近的证据也指出在胚胎干细胞分化中的不同作用。有趣的是，虽然Gremlin-2促进ES细胞分化为心房肌细胞，但NBL1支持神经表型。尽管如此，对Dan家族成员如何隔离BMP配体及其结构差异的了解仍然缺乏，这在很大程度上是由于缺乏对它们相互作用的结构洞察力。我们在这个提案中的目标是解决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)确定有效的DAN家族拮抗剂Gremlin-2与BMP的分子相互作用；(2)从结构上表征不同的DAN家族成员NBL1单独和与BMP的复合体，并确定BMP拮抗作用的不同基础；(3)从分子水平描述Gremlin-2和NBL1如何促进不同的ES细胞系。通过这些研究，我们期望对DAN：BMP相互作用有更深入的了解，这将支持以DAN拮抗剂为靶点的治疗学的发展。我们还期望这些结果将揭示引导ES细胞分化的机制。我们的研究将对BMP信号领域产生深远的整体影响，因为它们将极大地扩大我们对BMP配体如何被DAN家族成员对抗的理解。

 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.