The Asn418-linked N-glycan of ErbB3 plays a crucial role in preventing spontaneous heterodimerization and tumor promotion.
The Asn418-linked N-glycan of ErbB3 plays a crucial role in preventing spontaneous heterodimerization and tumor promotion.
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DOI：
10.1158/0008-5472.can-06-3023
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发表时间：
2007-03
期刊：
影响因子：
11.2
通讯作者：
Shunichi Yokoe;Motoko Takahashi;M. Asahi;Seung Ho Lee;Wei Li;D. Osumi;E. Miyoshi;N. Taniguchi
中科院分区：
文献类型：
--
作者：
Shunichi Yokoe;Motoko Takahashi;M. Asahi;Seung Ho Lee;Wei Li;D. Osumi;E. Miyoshi;N. Taniguchi
ErbB家族的两个成员ErbB 2和ErbB 3形成高亲和力的调蛋白辅助受体，其激发强有力的促有丝分裂和转化信号，并且临床研究表明这些受体在肿瘤的发生和发展中起重要作用。为了确定N-糖基化是否参与ErbB 3的功能，制备了一系列不含N-聚糖的人ErbB 3分子，并转染至Flp-In-CHO细胞中进行稳定表达。交联研究表明ErbB 3的Asn（418）到Gln突变体（N418 Q）在没有其配体heregulin的情况下经历了自身二聚化。ErbB 3的野生型或N418 Q突变体随后与ErbB 2在Flp-In-CHO细胞中共表达，并检查N-聚糖对异源二聚化的影响。ErbB 3的N418 Q突变体在没有配体刺激的情况下与ErbB 2自二聚化，并且在没有heregulin的情况下促进受体酪氨酸磷酸化和随后的细胞外信号调节激酶（ERK）和Akt磷酸化。细胞增殖试验和软琼脂集落形成试验表明，ErbB 3与ErbB 2共表达的N418 Q突变体以ERK和Akt依赖的方式促进细胞增殖和软琼脂集落形成。当皮下注射时，这种突变也促进了无胸腺小鼠肿瘤的生长。这些发现表明ErbB 3中Asn（418）连接的N-聚糖在调节ErbB 2的受体异源二聚化中起重要作用，并可能对转化活性产生影响。
ErbB2 and ErbB3, two members of the ErbB family, form a high-affinity heregulin coreceptor that elicits potent mitogenic and transforming signals, and clinical studies indicate that these receptors play an important role in tumor incidence and progression. To determine whether N-glycosylation is involved in the function of ErbB3, a series of human ErbB3 molecules devoid of N-glycans were prepared and transfected to Flp-In-CHO cells for stable expression. A cross-linking study showed that the Asn(418) to Gln mutant (N418Q) of ErbB3 underwent autodimerization without its ligand, heregulin. The wild-type or N418Q mutant of ErbB3 was next coexpressed with ErbB2 in Flp-In-CHO cells, and the effect of N-glycan on heterodimerization was examined. The N418Q mutant of ErbB3 was autodimerized with ErbB2 without ligand stimulation, and receptor tyrosine phosphorylation and subsequent extracellular signal-regulated kinase (ERK) and Akt phosphorylation were promoted in the absence of heregulin. A cell proliferation assay and a soft agar colony formation assay showed that the N418Q mutant of ErbB3 coexpressed with ErbB2 promoted cell proliferation and colony formation in soft agar in an ERK- and Akt-dependent manner. The mutation also promoted the growth of tumors in athymic mice when injected s.c. These findings suggest that the Asn(418)-linked N-glycan in ErbB3 plays an essential role in regulating receptor heterodimerization with ErbB2 and might have an effect on transforming activity.