Disruption of ligand binding to the insulin-like growth factor II/mannose 6-phosphate receptor by cancer-associated missense mutations
Disruption of ligand binding to the insulin-like growth factor II/mannose 6-phosphate receptor by cancer-associated missense mutations
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DOI：
10.1074/jbc.274.34.24408
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发表时间：
1999-08-20
影响因子：
4.8
通讯作者：
MacDonald, RG
中科院分区：
文献类型：
--
作者：
Byrd, JC;Devi, GR;MacDonald, RG
胰岛素样生长因子II/甘露糖6-磷酸受体（IGF2R）具有多种调节和转运功能，IGF2R功能的破坏被认为是增加细胞增殖的一种机制。在人类癌症中已经发现了几种错义IGF2R突变，包括以下发生在受体胞质外区域的氨基酸替换：Cys-1262—> Ser, Gln-1445—> His, Gly-1449—> Val, Gly-1464—> Glu和Ile-1572—> Thr。为了确定这些突变对IGF2R功能的影响，突变型和野生型FLAG表位标记的IGF2R构建体缺乏跨膜和细胞质结构域，可以结合胰岛素样生长因子(IGF)-II和一种名为PMP-BSA的含甘露糖6-磷酸假糖蛋白（PMP是五甘露糖磷酸，BSA是牛血清白蛋白）。il -1572 -> Thr突变消除了IGF-II的结合，但不影响PMP-BSA的结合。Gly-1449 -> Val和Cys-1262 -> Ser均显示可结合I-125-IGF-II和I-125-PMP-BSA的位点数量减少30-60%。此外，Gln-1445 -> His突变体经历了IGF-II结合的时间依赖性丧失，但没有PMP-BSA结合，这在野生型中没有观察到。总的来说，分析的五种癌症相关突变体中有四种表现出配体结合的改变，进一步证明IGF2R功能的丧失是某些癌症的特征。
The insulin-like growth factor II/mannose 6-phosphate receptor (IGF2R) carries out multiple regulatory and transport functions, and disruption of IGF2R function has been implicated as a mechanism to increase cell proliferation. Several missense IGF2R mutations have been identified in human cancers, including the following amino acid substitutions occurring in the extracytoplasmic domain of the receptor: Cys-1262 --> Ser, Gln-1445 --> His, Gly-1449 --> Val, Gly-1464 --> Glu, and Ile-1572 --> Thr. To determine what effects these mutations have on IGF2R function, mutant and wild-type FLAG epitope-tagged IGF2R constructs lacking the transmembrane and cytoplasmic domains were characterized for binding of insulin-like growth factor (IGF)-II and a mannose 6-phosphate-bearing pseudoglycoprotein termed PMP-BSA (where PMP is pentamannose phosphate and BSA is bovine serum albumin). The Ile-1572 --> Thr mutation eliminated IGF-II binding while not affecting PMP-BSA binding. Gly-1449 --> Val and Cys-1262 --> Ser each showed 30-60% decreases in the number of sites available to bind both I-125-IGF-II and I-125-PMP-BSA In addition, the Gln-1445 --> His mutant underwent a time-dependent loss of IGF-II binding, but not PMP-BSA binding, that was not observed for wild type. In all, four of the five cancer-associated mutants analyzed demonstrated altered ligand binding, providing further evidence that loss of IGF2R function is characteristic of certain cancers.