GPIHBP1 missense mutations often cause multimerization of GPIHBP1 and thereby prevent lipoprotein lipase binding.
GPIHBP1 missense mutations often cause multimerization of GPIHBP1 and thereby prevent lipoprotein lipase binding.
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DOI：
10.1161/circresaha.116.305085
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发表时间：
2015-02-13
影响因子：
20.1
通讯作者：
Young SG
中科院分区：
文献类型：
--
作者：
Beigneux AP;Fong LG;Bensadoun A;Davies BS;Oberer M;Gårdsvoll H;Ploug M;Young SG
GPIHBP1是毛细血管内皮细胞的一种gpi锚定蛋白，它与内皮下空间的脂蛋白脂肪酶（LPL）结合，并将其运送到毛细血管腔。干扰LPL结合的GPIHBP1错义突变导致家族性乳糜微粒血症。我们试图了解GPIHBP1突变阻止LPL结合并导致乳糜微粒血症的机制。我们在中国仓鼠卵巢细胞、大鼠和人内皮细胞以及果蝇S2细胞中表达了GPIHBP1的突变形式。在每个表达系统中，GPIHBP1的Ly6结构域的半胱氨酸突变（包括在乳糜小铁血症患者中发现的突变）导致二硫连接二聚体和多聚体的形成。GPIHBP1二聚化/多聚化并不是半胱氨酸突变所独有的；其他氨基酸残基的突变，包括一些与乳糜微粒血症相关的氨基酸残基，也会导致蛋白质二聚化/多聚化。GPIHBP1单体的缺失与乳糜微粒血症的发病机制密切相关，因为只有GPIHBP1单体能够结合LPL，而非二聚体或多聚体。GPIHBP1突变体GPIHBP1- w109s具有独特的特性。GPIHBP1-W109S缺乏结合LPL的能力，但形成二聚体或多聚体的倾向降低，这表明W109可能在结合LPL中发挥更直接的作用。为了支持这一观点，用其他8种氨基酸中的任何一种代替W109可以消除LPL结合，而且通常不会促进二聚体和多聚体的形成。GPIHBP1的Ly6结构域的许多氨基酸取代导致蛋白质二聚化/多聚化。考虑到只有GPIHBP1单体能够结合LPL，二聚化/多聚化与疾病发病机制有关。
GPIHBP1, a GPI-anchored protein of capillary endothelial cells, binds lipoprotein lipase (LPL) in the subendothelial spaces and shuttles it to the capillary lumen. GPIHBP1 missense mutations that interfere with LPL binding cause familial chylomicronemia. We sought to understand mechanisms by which GPIHBP1 mutations prevent LPL binding and lead to chylomicronemia. We expressed mutant forms of GPIHBP1 in Chinese hamster ovary cells, rat and human endothelial cells, and Drosophila S2 cells. In each expression system, mutation of cysteines in GPIHBP1’s Ly6 domain (including mutants identified in chylomicronemia patients) led to the formation of disulfide-linked dimers and multimers. GPIHBP1 dimerization/multimerization was not unique to cysteine mutations; mutations in other amino acid residues, including several associated with chylomicronemia, also led to protein dimerization/multimerization. The loss of GPIHBP1 monomers is quite relevant to the pathogenesis of chylomicronemia because only GPIHBP1 monomers—and not dimers or multimers—are capable of binding LPL. One GPIHBP1 mutant, GPIHBP1-W109S, had distinctive properties. GPIHBP1-W109S lacked the ability to bind LPL but had a reduced propensity for forming dimers or multimers, suggesting that W109 might play a more direct role in binding LPL. In support of that idea, replacing W109 with any of 8 other amino acids abolished LPL binding—and often did so without promoting the formation of dimers and multimers. Many amino acid substitutions in GPIHBP1’s Ly6 domain that abolish LPL binding lead to protein dimerization/multimerization. Dimerization/multimerization is relevant to disease pathogenesis, given that only GPIHBP1 monomers are capable of binding LPL.