Molecular basis of a novel oncogenic mutation in GNAO1.
Molecular basis of a novel oncogenic mutation in GNAO1.
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DOI：
10.1038/onc.2010.645
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发表时间：
2011-06-09
期刊：
影响因子：
8
通讯作者：
Farquhar, M. G.
中科院分区：
文献类型：
--
作者：
Garcia-Marcos, M.;Ghosh, P.;Farquhar, M. G.
异三聚体G蛋白是控制信号转导的分子开关，其失调可促进肿瘤的发生。GNAs、GNAI2和GNAQ基因的体细胞突变通过使Gα亚基结构性激活来诱导肿瘤的发生。最近在乳腺癌中发现了第一个体细胞突变，GNA01(G→o)基因中的精氨酸243α组氨酸(R243H)，并被证明导入细胞后可以促进肿瘤的转化。在此，我们为Gαo R243H突变体的致癌特性提供了分子基础。通过有限的蛋白质分解分析、核苷酸结合分析以及单周转和稳态GTP酶分析，我们证明致癌基因R234H突变通过加快核苷酸交换速度而使Gαo具有结构性活性；然而，该突变不影响Gαo被GTP酶激活蛋白(GAP)或其固有的GTP酶活性失活的能力。这一机制不同于以前报道的癌基因突变，后者损害了GTP酶的活性和缺口敏感性，而不影响核苷酸交换。具有结构性活性的Gαo R243H突变体还增强了NIH-3T3细胞中的src-α3信号，这一途径以前被证明是由激活的G STATo蛋白直接触发的，以促进细胞转化。根据结构分析，我们认为Gαo R243H中核苷酸交换速率的提高是由于R243与E43之间高度保守的静电相互作用的丧失，E43位于P-环中，代表核苷酸的α和β-磷酸结合部位。我们的结论是，新的R234H突变通过加速核苷酸交换并使其具有结构性活性，从而增强了负责肿瘤转化的信号通路，如src-α3，从而赋予G STATo致癌特性。
Heterotrimeric G proteins are molecular switches that control signal transduction and their dysregulation can promote oncogenesis. Somatic mutations in GNAS, GNAI2 and GNAQ genes induce oncogenesis by rendering Gα-subunits constitutively activated. Recently the first somatic mutation, Arginine243 → Histidine (R243H) in the GNAO1 (Gαo) gene was identified in breast carcinomas and shown to promote oncogenic transformation when introduced into cells. Here we provide the molecular basis for the oncogenic properties of the Gαo R243H mutant. Using limited proteolysis assays, nucleotide binding assays, and single-turnover and steady-state GTPase assays, we demonstrate that the oncogenic R234H mutation renders Gαo constitutively active by accelerating the rate of nucleotide exchange; however, this mutation does not affect Gαo’s ability to become deactivated by GTPase Activating Proteins (GAPs) or by its intrinsic GTPase activity. This mechanism differs from that of previously reported oncogenic mutations which impair GTPase activity and GAP sensitivity without affecting nucleotide exchange. The constitutively active Gαo R243H mutant also enhances Src-STAT3 signaling in NIH-3T3 cells, a pathway previously shown to be directly triggered by active Gαo proteins to promote cellular transformation. Based on structural analyses we promose that the enhanced rate of nucleotide exchange in Gαo R243H results from loss of the highly conserved electrostatic interaction of R243 with E43, located in the in the P-loop which represents the binding site for the α and β-phosphates of the nucleotide. We conclude that the novel R234H mutation imparts oncogenic properties to Gαo by accelerating nucleotide exchange and rendering it constitutively active, thereby enhancing signaling pathways, e.g., src-STAT3, responsible for neoplastic transformation.
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影响因子：
3.7
作者：
Lamba S;Felicioni L;Buttitta F;Bleeker FE;Malatesta S;Corbo V;Scarpa A;Rodolfo M;Knowles M;Frattini M;Marchetti A;Bardelli A
通讯作者：
Bardelli A
DOI：
10.1073/pnas.0704751104
发表时间：
2007-10-30
影响因子：
11.1
作者：
Johnston, Christopher A.;Taylor, J. Philip;Willard, Francis S.
通讯作者：
Willard, Francis S.
影响因子：
4.8
作者：
Garcia-Marcos, Mikel;Ghosh, Pradipta;Farquhar, Marilyn G.
通讯作者：
Farquhar, Marilyn G.
影响因子：
64.8
作者：
LANDIS, CA;MASTERS, SB;VALLAR, L
通讯作者：
VALLAR, L
影响因子：
16.2
作者：
Doi, M;Iwasaki, K
通讯作者：
Iwasaki, K