Epileptic and developmental disorders of the speech cortex: ligand/receptor interaction of wild-type and mutant SRPX2 with the plasminogen activator receptor uPAR
Epileptic and developmental disorders of the speech cortex: ligand/receptor interaction of wild-type and mutant SRPX2 with the plasminogen activator receptor uPAR
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DOI：
10.1093/hmg/ddn256
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发表时间：
2008-12-01
影响因子：
3.5
通讯作者：
Szepetowski, Pierre
中科院分区：
文献类型：
--
作者：
Royer-Zemmour, Barbara;Ponsole-Lenfant, Magali;Szepetowski, Pierre
SRPX 2（Sushi-Repeat Protein，X连锁2）突变可导致罗兰癫痫伴语言障碍（RESDX综合征）或语言皮层发育改变（双侧侧裂周多微回）。迄今为止，SRPX 2的生理作用仍然未知。推断SRPX 2功能的一种方法依赖于对迄今未知的SRPX 2蛋白伴侣的鉴定。利用酵母双杂交筛选、免疫共沉淀实验、细胞表面结合和表面等离子体共振（SPR）等相互作用组学方法的组合，我们证明了SRPX 2是uPAR（尿激酶型纤溶酶原激活物（uPA）受体）的配体。先前的研究表明，uPAR（-/-）敲除小鼠表现出对癫痫发作的易感性增强，并具有与改变的神经元迁移和成熟一致的脑皮质异常，所有这些特征都让人联想到SRPX 2突变引起的表型。SPR分析表明，与Rolandic癫痫和侧裂周多小脑回相关的p.Y72S突变导致SRPX 2与uPAR的亲和力增加5.8倍。uPAR是细胞外纤溶酶原蛋白水解系统的关键组分;此处鉴定的另外两种SRPX 2配偶体，半胱氨酸蛋白酶组织蛋白酶B（CTSB）和金属蛋白酶ADAMTS 4，也是细胞外蛋白水解机制的组分，CTSB是uPA的众所周知的激活剂。功能相关的SRPX 2合作伙伴的鉴定提供了第一个和令人兴奋的见解SRPX 2在大脑中的可能作用，并表明，SRPX 2相互作用的蛋白质网络经典参与细胞外基质的蛋白水解重塑，包括uPAR参与的功能，在发展和言语皮层的疾病。
Mutations in SRPX2 (Sushi-Repeat Protein, X-linked 2) cause rolandic epilepsy with speech impairment (RESDX syndrome) or with altered development of the speech cortex (bilateral perisylvian polymicrogyria). The physiological roles of SRPX2 remain unknown to date. One way to infer the function of SRPX2 relies on the identification of the as yet unknown SRPX2 protein partners. Using a combination of interactome approaches including yeast two-hybrid screening, co-immunoprecipitation experiments, cell surface binding and surface plasmon resonance (SPR), we show that SRPX2 is a ligand for uPAR, the urokinase-type plasminogen activator (uPA) receptor. Previous studies have shown that uPAR(-/-) knock-out mice exhibited enhanced susceptibility to epileptic seizures and had brain cortical anomalies consistent with altered neuronal migration and maturation, all features that are reminiscent to the phenotypes caused by SRPX2 mutations. SPR analysis indicated that the p.Y72S mutation associated with rolandic epilepsy and perisylvian polymicrogyria, led to a 5.8-fold gain-of-affinity of SRPX2 with uPAR. uPAR is a crucial component of the extracellular plasminogen proteolysis system; two more SRPX2 partners identified here, the cysteine protease cathepsin B (CTSB) and the metalloproteinase ADAMTS4, are also components of the extracellular proteolysis machinery and CTSB is a well-known activator of uPA. The identification of functionally related SRPX2 partners provides the first and exciting insights into the possible role of SRPX2 in the brain, and suggests that a network of SRPX2-interacting proteins classically involved in the proteolytic remodeling of the extracellular matrix and including uPAR participates in the functioning, in the development and in disorders of the speech cortex.