研究动态
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对生殖系KRAS T50I突变的结构和功能分析为Raf活化提供了启示。

Structural and functional analyses of a germline KRAS T50I mutation provide insights into Raf activation.

发表日期:2023 Sep 08
作者: Pan-Yu Chen, Benjamin J Huang, Max Harris, Christopher Boone, Weijie Wang, Heidi Carias, Brian Mesiona, Daniela Mavrici, Amanda C Kohler, Gideon Bollag, Chao Zhang, Ying Zhang, Kevin Shannon
来源: JCI Insight

摘要:

K-Ras间隙结构域中的T50I替换引起了Noonan综合征,并且在小鼠白血病模型中出现为第三位点突变,通过使减弱的KrasG12D,E37G癌基因恢复了体内的转化活性和MAPK通路的活化。生化和晶体学数据表明,K-RasT50I通过一种非GTP酶机制增加了MAPK信号输出,可能是通过促进T50和E162之间非对称的Ras:Ras相互作用来实现的。我们生成了一个“可切换”的系统,其中在生理水平上表达的K-Ras突变蛋白替代了缺乏内源性KRAS的MOLM-13白血病细胞对fms like酪氨酸激酶3(FLT3)的依赖性,并利用该系统对单个或复合的G12D、T50I、D154Q和E162L突变进行了研究。这些研究支持K-Ras的非对称横向组装在质膜远离方向上起到关键作用,促进了在质膜近端构象中形成活性Ras:Raf复合物的形成。诸如T50I这样的致病突变是研究正常Ras功能、揭示疾病机制和识别Ras病和癌症的潜在治疗机会的有价值的起点。
A T50I substitution in the K-Ras interswitch domain causes Noonan syndrome and emerged as a third-site mutation that restored the in vivo transforming activity and constitutive MAPK pathway activation by an attenuated KrasG12D,E37G oncogene in a mouse leukemia model. Biochemical and crystallographic data suggested that K-RasT50I increases MAPK signal output through a non-GTPase mechanism, potentially by promoting asymmetric Ras:Ras interactions between T50 and E162. We generated a "switchable" system in which K-Ras mutant proteins expressed at physiologic levels supplant the fms like tyrosine kinase 3 (FLT3) dependency of MOLM-13 leukemia cells lacking endogenous KRAS and used this system to interrogate single or compound G12D, T50I, D154Q, and E162L mutations. These studies support a key role for the asymmetric lateral assembly of K-Ras in a plasma membrane-distal orientation that promotes the formation of active Ras:Raf complexes in a membrane-proximal conformation. Disease-causing mutations such as T50I are a valuable starting point for illuminating normal Ras function, elucidating mechanisms of disease, and identifying potential therapeutic opportunities for Rasopathy disorders and cancer.