The modular adaptor protein autosomal recessive hypercholesterolemia (ARH) promotes low density lipoprotein receptor clustering into clathrin-coated pits
The modular adaptor protein autosomal recessive hypercholesterolemia (ARH) promotes low density lipoprotein receptor clustering into clathrin-coated pits
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DOI：
10.1074/jbc.m509394200
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发表时间：
2005-12-09
影响因子：
4.8
通讯作者：
Hobbs, HH
中科院分区：
文献类型：
--
作者：
Garuti, R;Jones, C;Hobbs, HH
常染色体隐性高胆固醇血症的特征是低密度脂蛋白受体 (LDLR) 内吞作用中细胞类型特异性缺陷。 LDLR 介导的 LDL 摄取在肝脏中受损，但在患有这种疾病的受试者的成纤维细胞中却没有受损。该疾病是由 ARH 突变引起的，ARH 编码一种推定的衔接蛋白，在体外与 LDLR 的细胞质尾部、磷脂和网格蛋白内吞机制的两个成分（网格蛋白和衔接蛋白 2 (AP-2)）相互作用。为了确定这些相互作用的生理相关性，我们检查了 ARH 突变对极化肝细胞 (WIF-B) 中 LDLR 位置和功能的影响。 LDLR 细胞质尾部 FDNPVY 序列的完整性对于 ARH 相关 LDLR 聚集成网格蛋白包被的凹坑是必需的。 ARH 的磷酸酪氨酸结合域加上网格蛋白盒或 AP-2 结合区是 LDLR 的聚类和内化所必需的。在 Arh(-/-) 小鼠肝脏中使用相同重组形式的 ARH 进行的体内平行研究证实了细胞培养结果的相关性。这些结果表明，ARH 必须结合 LDLR 尾部以及网格蛋白或 AP-2，以促进 LDL 受体聚集和内化。
Autosomal recessive hypercholesterolemia is characterized by a cell type-specific defect in low density lipoprotein receptor ( LDLR) endocytosis. LDLR-mediated uptake of LDL is impaired in the liver, but not in fibroblasts of subjects with this disorder. The disease is caused by mutations in ARH, which encodes a putative adaptor protein that interacts with the cytoplasmic tail of the LDLR, phospholipids, and two components of the clathrin endocytic machinery, clathrin and adaptor protein-2 (AP-2) in vitro. To determine the physiological relevance of these interactions, we examined the effect of mutations in the ARH on LDLR location and function in polarized hepatocytes (WIF-B). The integrity of the FDNPVY sequence in the LDLR cytoplasmic tail was required for ARH-associated LDLR clustering into clathrin-coated pits. The phosphotyrosine binding domain of ARH plus either the clathrin box or the AP-2 binding region were required for both clustering and internalization of the LDLR. Parallel studies performed in vivo with the same recombinant forms of ARH in livers of Arh(-/-) mice confirmed the relevance of the cell culture findings. These results demonstrate that ARH must bind the LDLR tail and either clathrin or AP-2 to promote receptor clustering and internalization of LDL.