Diverse effects of mutations in Exon II of the von Hippel-Lindau (VHL) tumor suppressor gene on the interaction of pVHL with the cytosolic chaperonin and pVHL-dependent ubiquitin ligase activity
Diverse effects of mutations in Exon II of the von Hippel-Lindau (VHL) tumor suppressor gene on the interaction of pVHL with the cytosolic chaperonin and pVHL-dependent ubiquitin ligase activity
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DOI：
10.1128/mcb.22.6.1947-1960.2002
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发表时间：
2002-03-01
影响因子：
5.3
通讯作者：
Welch, WJ
中科院分区：
文献类型：
--
作者：
Hansen, WJ;Ohh, M;Welch, WJ
我们在体外和体内研究了von Hippel-Lindau（VHL）肿瘤抑制蛋白（pVHL）的生物发生。pVHL在与延伸蛋白B/C组装并随后形成VCB-Cul 2泛素连接酶的过程中与含有TCP-1（CCT或TRiC）的胞质伴侣蛋白形成复合物。阻断pVHL与延伸蛋白WC的相互作用导致pVHL在CCT复合物内积累。纯化的VHL-CCT复合物中存在的pVHL，当添加到兔网织红细胞裂解物中时，继续形成VCB和VCB-Cul 2。因此，CCT可能至少部分地通过保留VHL链而起作用，等待延长蛋白B/C用于最终折叠和/或组装的可用性。VHL综合征外显子11内的肿瘤相关突变对含pVHL复合物的稳定性和/或功能有不同的影响。首先，缺失由外显子11编码的整个区域的pVHL突变体不与CCT结合，但仍然可以与延伸蛋白B/C和延伸蛋白B/C-Cul 2组装成复合物。第二，外显子11中的一些肿瘤源性错义突变没有降低CCT结合，并且大多数对VCB-Cul 2组装没有可检测的影响。然而，许多外显子11突变体被发现在与低氧诱导因子1 α（HIF-1 α）的结合和随后的泛素化中存在缺陷，HIF-1 α是VCB-Cul 2泛素连接酶的底物。我们的结论是选择压力突变VHL外显子11在肿瘤发生过程中不涉及CCT结合的损失，但可能反映定量或定性缺陷HIF结合和/或pVHL依赖性泛素连接酶活性。
We examined the biogenesis of the von Hippel-Lindau (VHL) tumor suppressor protein (pVHL) in vitro and in vivo. pVHL formed a complex with the cytosolic chaperonin containing TCP-1 (CCT or TRiC) en route to assembly with elongin B/C and the subsequent formation of the VCB-Cul2 ubiquitin ligase. Blocking the interaction of pVHL with elongin WC resulted in accumulation of pVHL within the CCT complex. pVHL present in purified VHL-CCT complexes, when added to rabbit reticulocyte lysate, proceeded to form VCB and VCB-Cul2. Thus, CCT likely functions, at least in part, by retaining VHL chains pending the availability of elongin B/C for final folding and/or assembly. Tumor-associated mutations within exon 11 of the VHL syndrome had diverse effects upon the stability and/or function of pVHL-containing complexes. First, a pVHL mutant lacking the entire region encoded by exon 11 did not bind to CCT and yet could still assemble into complexes with elongin B/C and elongin B/C-Cul2. Second, a number of tumor-derived missense mutations in exon 11 did not decrease CCT binding, and most had no detectable effect upon VCB-Cul2 assembly. Many exon 11 mutants, however, were found to be defective in the binding to and subsequent ubiquitination of hypoxia-inducible factor 1alpha (HIF-1alpha), a substrate of the VCB-Cul2 ubiquitin ligase. We conclude that the selection pressure to mutate VHL exon 11 during tumorigenesis does not relate to loss of CCT binding but may reflect quantitative or qualitative defects in HIF binding and/or in pVHL-dependent ubiquitin ligase activity.