Targeted genomic disruption of H-ras and N-ras, individually or in combination, reveals the dispensability of both loci for mouse growth and development
Targeted genomic disruption of H-ras and N-ras, individually or in combination, reveals the dispensability of both loci for mouse growth and development
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DOI：
10.1128/mcb.21.5.1444-1452.2001
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发表时间：
2001-03-01
影响因子：
5.3
通讯作者：
Santos, E
中科院分区：
文献类型：
--
作者：
Esteban, LM;Vicario-Abejón, C;Santos, E
哺乳动物细胞具有ras家族的三个高度同源且广泛表达的成员（H-ras、N-ras和Ii-ras），但仍不清楚它们是否发挥特定或重叠的细胞作用。为了深入了解这些功能作用，我们在这里产生并分析了H-ras nun突变小鼠，然后将其与N-ras敲除动物一起繁殖，以确定两个基因座中潜在双无效突变的可行性和特性。杂合子H-ras（+/-）小鼠交配产生的H-ras（-/-）后代具有正常的孟德尔遗传模式，表明II-ras的缺失不会干扰胚胎和胎儿在子宫内的生存能力。纯合子突变H-ras（-/-）小鼠达到性成熟的年龄与他们的同窝出生，男性和女性都是可生育的。脾脏和胸腺中淋巴细胞亚群的特征显示野生型和H-ras（-/-）小鼠之间无显著差异。对基因敲除和野生型H-ras小鼠大脑中的神经元标记物的分析表明，该位点的破坏不会损害或改变神经元的发育。在我们的K-ras突变动物和先前可用的N-ras无效突变体之间的育种产生了仅表达K-ras基因的可行的双敲除（H-ras（-/-）/N-ras（-/-））后代，其正常生长，可育，并且没有显示任何明显的表型。然而，有趣的是，在杂合N-ras/H-ras小鼠之间的孟德尔杂交中，始终获得低于预期的成年双敲除动物的数量。我们的结果表明，对于N-ras，H-ras基因功能对于正常小鼠发育生长，生育力和神经元发育是不重要的。此外，在三种ras基因中，K-ras似乎不仅是必需的，而且对于正常小鼠发育也是足够的。
Mammalian cells harbor three highly homologous and widely expressed members of the ras family (H-ras, N-ras, and Ii-ras), but it remains unclear whether they play specific or overlapping cellular roles. To gain insight into such functional roles, here we generated and analyzed H-ras nun mutant mice, which were then also bred with N-ras knockout animals to ascertain the viability and properties of potential double null mutations in both loci. Mating among heterozygous H-ras(+/-) mice produced H-ras(-/-) offspring with a normal Mendelian pattern of inheritance, indicating that the loss of II-ras did not interfere with embryonic and fetal viability in the uterus. Homozygous mutant H-ras(-/-) mice reached sexual maturity at the same age as their littermates, and both males and females were fertile. Characterization of lymphocyte subsets in the spleen and thymus showed no significant differences between wild-type and H-ras(-/-) mice. Analysis of neuronal markers in the brains of knockout and wild-type H-ras mice showed that disruption of this locus did not impair or alter neuronal development. Breeding between our K-ras mutant animals and previously available N-ras null mutants gave rise to viable double knockout (H-ras(-/-)/N-ras(-/-)) offspring expressing only K-ras genes which grew normally, were fertile, and did not show any obvious phenotype. Interestingly, however, lower-than-expected numbers of adult, double knockout animals were consistently obtained in Mendelian crosses between heterozygous N-ras/H-ras mice, Our results indicate that, as for N-ras, H-ras gene function is dispensable for normal mouse development growth, fertility, and neuronal development. Additionally, of the three ras genes, K-ras appears to be not only essential but also sufficient for normal mouse development.