P53 MISSENSE MUTATIONS ON TUMORIGENESIS AND VIVO

描述：(逐字改编自调查人员的摘要) 含有P53零等位基因的小鼠模型的发展在 破译P53抑癌基因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缺失的小鼠不代表大多数 所发生的突变。这项建议中要检验的假设是 错义突变代表显性负性或功能获得表型 在活体内。我们已经生成了一个鼠标，该鼠标在 对应于六个热点突变之一的内源性p53基因(氨基酸 在人类肿瘤中。这只小鼠还含有G核苷酸的缺失 在外显子3的剪接受体处，表达突变蛋白 水平与野生型P53相似。另一只包含Arg-to-His的鼠标 在更高水平表达的突变也将发生。为了测试 这种突变的显性负性和功能获得性，我们将比较 存在或不存在P53零等位基因时的p53R172H突变 肿瘤发生的时间和谱系。在人类身上发现的另一种突变 这种氨基酸的肿瘤会将精氨酸175转化为脯氨酸。这个突变体保留了 在G1期抑制生长的能力，但不能诱导细胞凋亡 组织培养。含有该点突变的ES细胞已被鉴定 并将开发一种小鼠模型。这一模式将在 理解P53生长停滞和细胞凋亡的相对作用 对体内肿瘤发生的作用。P53R172H和p53R172P小鼠也将 与MDM2杂合子小鼠交配以监测由于 失去MDM2。推迟MDM2基因缺失小鼠致死率的可能性将 提供机会来研究P53/MDM2相互作用在 以后的发展。这些老鼠模型将有助于洞察不同之处。 P53错义突变在肿瘤发生的时间和谱系之间的关系。

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.