Signaling by Shp2 mutants in RASopathies

摘要/项目摘要 先天性心脏缺陷（CHD）是最常见的出生缺陷类型（约1/100活产）， 与出生有关的死亡原因。已知Ras/丝裂原活化蛋白激酶（MAPK）通路中的突变 称为“RASopathies”，包括努南综合征（NS）和努南综合征伴多发性雀斑样痣（NSML） 表现为各种临床问题，但最显著的是冠心病。NS和NSML患者表现出一系列 CHD相关异常，如肺动脉瓣狭窄、肥厚型心肌病和房间隔 缺陷大约50%的NS和90%的NSML患者具有常染色体显性突变， PTPN 11，编码含SH 2结构域的蛋白酪氨酸磷酸酶Shp 2的基因。NS表示 是冠心病最常见的非染色体病因。因此，了解NS的机制， 随后NSML将提供对某些形式的CHD的病因的深入了解。使用一套完整的 包括磷酸蛋白质组学、斑马鱼遗传学、生物化学和细胞生物学的方法， 一种与Shp 2结合的跨膜糖蛋白--零相关蛋白（PZR），是一种新的靶蛋白 参与心脏发育。PZR被鉴定为其酪氨酰水平异常增加， NS和NSML小鼠模型心脏中的磷酸化表明PZR是共同的靶点 这些种族主义者因此，本申请的目的是1）定义分子决定簇 管理PZR的下游信令，并确定PZR如何作为公共信令目标， NS和NSML，2）测试低剂量酪氨酸激酶抑制剂破坏异常PZR/Shp 2的功效 信号传导以改善NS和NSML相关CHD的发展，以及3）产生新的PZR小鼠 模型来确定PZR在NS和NSML相关CHD发展中的作用。总的来说，这些 研究结果将提供对NS和NSML相关CHD共同机制的深入了解。最后， 将揭示NS/NSML相关CHD潜在治疗的新策略。

Abstract/Project Summary Congenital heart defects (CHDs) are the most common type of birth defect (~1/100 live births) and the major cause of birth-related deaths. Mutations in the Ras/mitogen-activated protein kinase (MAPK) pathway known as “RASopathies” that include Noonan syndrome (NS) and Noonan syndrome with multiple lentigines (NSML) manifest in a variety of clinical problems but most notably, CHDs. NS and NSML patients exhibit a range of CHD-related anomalies such as pulmonic valve stenosis, hypertrophic cardiomyopathy and atrial septal defects. Approximately, 50% of NS and 90% of NSML patients have autosomal dominant mutations in PTPN11, the gene encoding the SH2 domain-containing protein tyrosine phosphatase, Shp2. NS represents the most common non-chromosomal cause of CHD. Therefore, understanding the mechanisms of NS, and subsequently NSML, will provide insight into the causation of some forms of CHD. Using an integrated set of approaches that include phospho proteomics, zebrafish genetics, biochemistry and cell biology we have identified protein zero-related (PZR), a transmembrane glycoprotein that binds Shp2, as a novel target protein involved in heart development. PZR was identified to be aberrantly increased in its levels of tyrosyl phosphorylation in the heart of mouse models of both NS and NSML suggesting that PZR is a common target of these RASopathies. Therefore, the aims of this application are to 1) define the molecular determinants governing downstream signaing of PZR and to determine how PZR serves as a common signaling target for NS and NSML, 2) test the efficacy of low-dose tyrosine kinase inhibitors to disrupt aberrant PZR/Shp2 signaling to ameliorate the development of NS- and NSML-related CHD and 3) generate novel PZR mouse models to define the contribution of PZR in the development of NS and NSML-related CHD. Collectively, these results will provide insight into common mechanisms that underlie both NS and NSML-related CHD. Finally, novel strategies for the potential treatment of NS/NSML-associated CHD will be uncovered.