Ha-ras and N-ras regulate MAPK activity by distinct mechanisms in vivo
Ha-ras and N-ras regulate MAPK activity by distinct mechanisms in vivo
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DOI：
10.1038/sj.onc.1201653
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发表时间：
1998-03-19
期刊：
影响因子：
8
通讯作者：
Wolfman, A
中科院分区：
文献类型：
--
作者：
Hamilton, M;Wolfman, A
Ras GTP酶作为分子开关发挥作用，调节多种生物学事件，然而，特定c-Ras异构体的贡献（如果有的话），（Ha-、N-或Ki-ras A或B）在给定的生物学或生物化学过程的调节中的作用是未知的，用活化的（G12 V）Ha-ras或（Q61 K）N-ras转化的鼠C3 H10 T12成纤维细胞在无血清培养基中增殖并具有组成型MAPK活性，生长因子拮抗剂苏拉明抑制Ha-ras转化成纤维细胞的非血清依赖性增殖，但不抑制N-ras转化细胞的非血清依赖性增殖。对Ha-ras转化细胞免疫沉淀物中Ras信号复合物的分析表明，Raf-1与内源性c-N-ras共免疫沉淀，而与（G12 V）Ha-ras不共免疫沉淀。苏拉明预处理可使c-N-ras免疫沉淀物中Raf-1的表达减少，c-N-ras反义寡核苷酸可下调c-N-ras蛋白水平，抑制（G_（12）V）Ha-ras转化细胞的MAPK活性和非血清依赖性增殖。而Ha-ras转化细胞的血清非依赖性增殖需要c-N-ras功能。
The Ras GTPases function as molecular switches, regulating a multiplicity of biological events, However the contribution, if any, of a specific c-Ras isoform (Ha-, N-, or Ki-ras A or B) in the regulation of a given biological or biochemical process, is unknown, Murine C3H10T1/2 fibroblasts transformed with activated (G12V)Ha-ras or (Q61K)N-ras proliferate in serum-free media and have constitutive MAPK activity, The growth factor antagonist, suramin, inhibited the serum-independent proliferation of Ha-ras transformed fibroblasts, but not the serum-independent proliferation of N-ras transformed cells. The inhibition of cell proliferation was concomitant with the abrogation of the constitutive MAPK activity in the Ha-ras transformed fibroblasts, Analysis of the Ras-signalling complexes in immunoprecipitates from Ha-ras transformed cells revealed that Raf-1 co-immunoprecipitated with endogenous c-N-ras but not (G12V)Ha-ras. Pretreatment with suramin resulted in the loss of Raf-1 from c-N-ras immunoprecipitates, A c-N-ras antisense oligonucleotide, which down-regulated c-N-ras protein levels, abrogated the constitutive MAPK activity and serum-independent proliferation of (G12V)Ha-ras transformed cells, The data suggest that Raf-1 has a higher affinity for N-ras then Ha-ras in vivo, and c-N-ras function is required for the serum-independent proliferation of Ha-ras transformed cells.