P53 MISSENSE MUTATIONS ON TUMORIGENESIS AND VIVO

描述：（逐字改编自研究者摘要） 含有p53无效等位基因的小鼠模型的开发在 解释p53肿瘤抑制因子在肿瘤发生中的重要性。 然而，超过80%的p53改变是DNA中的错义突变。 因此，p53敲除小鼠不代表大多数 发生的突变。本提案中要检验的假设是， 错义突变代表显性阴性或功能获得型 in vivo.我们已经生成了一个在 内源性p53基因对应于六个热点突变之一（氨基酸 175)in human人tumors肿瘤.这只小鼠也含有G核苷酸的缺失 在外显子3的剪接受体位点，并在 与野生型p53相似。另一只携带arg-to-his基因的老鼠 也将产生以更高水平表达的突变。为了测试 显性负性和功能获得性突变的性质，我们将比较 在存在或不存在p53无效等位基因的情况下， 肿瘤发展的时间和范围。在人类中发现的另一种突变 肿瘤在此氨基酸处将精氨酸175改变为脯氨酸。这种突变体保留了 在G1中抑制生长的能力，但在G2中测定时不诱导细胞凋亡。 组织培养含有这种点突变的ES细胞已被鉴定 并将开发小鼠模型。这种模式将是至关重要的， 了解p53生长停滞和凋亡的相对作用 在体内对肿瘤发生起作用。p53 R172 H和p53 R172 P小鼠也将被 与mdm 2杂合子小鼠交配，以监测 MDM 2的丢失。延迟mdm 2缺失小鼠致死的可能性将 提供机会来研究p53/MDM 2相互作用的重要性， 后来的发展。这些小鼠模型将使我们深入了解 p53错义突变在肿瘤发展的时间和范围之间的关系。

DESCRIPTION: (adapted verbatim from the investigator's abstract) The development of mouse models containing a p53 null allele has been invaluable in deciphering the importance of the p53 tumor suppressor in tumorigenesis. However, greater than 80% of p53 alterations are misense mutations in the DNA binding domain and as such, the p53 null mouse does no represent the majority of mutations that occur. The hypothesis to be tested in this proposal is that missense mutations represent a dominant-negative or gain-of-function phenotype in vivo. We have generated a mouse containing an arg-to-his substitution in the endogenous p53 gene corresponding to one of six hotspot mutations (amino acid 175) in human tumors. This mouse also contains the deletion of a G nucleotide at the splice acceptor site of exon 3 and expresses the mutant protein at levels similar to wild type p53. Another mouse containing the arg-to-his mutation expressed at higher levels will also be made. In order to test the dominant-negative and gain-of-function nature of this mutation, we will compare the p53R172H mutations in the presence or absence of a p53 null allele for timing and spectrum of tumor development. Another mutation found in human tumors at this amino acid alters arginine 175 to proline. This mutant retains the ability to arrest growth in G1, but not to induce apoptosis when assayed in tissue culture. ES cells containing this point mutation have been identified and a mouse model will be developed. This model will be crucial in understanding the relative contribution of p53 growth arrest and apoptotic functions to tumorigenesis in vivo. The p53R172H and p53R172P mice will also be mated with mdm2 heterozygous mice to monitor effects on embryo lethality due to loss of mdm2. The possibility of delaying lethality of mdm2 null mice will afford the opportunity to examine the importance of the p53/MDM2 interaction in later development. These mouse models will yield insight into differences between p53 missense mutations in the timing and spectrum of tumor development.