Muscolini Michela, Montagni Elisa, Caristi Silvana, Nomura Takao, Kamada Rui, Di Agostino Silvia, Corazzari Marco, Piacentini Mauro, Blandino Giovanni, Costanzo Antonio, Sakaguchi Kazuyasu, Tuosto Loretta
Istituto Pasteur-Fondazione Cenci Bolognetti, Department of Cellular Biology and Development, Sapienza University, Italy.
Cell Cycle. 2009 Oct 15;8(20):3396-405. doi: 10.4161/cc.8.20.9910. Epub 2009 Oct 24.
Inactivation of the tumor suppressor p53 is central to carcinogenesis and acquisition of resistance to drug-induced apoptosis. The majority of alterations are missense mutations and occur within the DNA-binding domain. However, little is known about the point mutations in the tetramerization domain (TD). Here we investigated the properties of a new p53 mutant (Lys 351 to Asn) in the TD identified in a cisplatin-resistant ovarian carcinoma cell line (A2780 CIS). We found that K351N substitution significantly reduces the thermodynamic stability of p53 tetramers without affecting the overall half-life of the protein. Moreover, p53 K351N has a reduced ability to bind DNA and to trans-activate its specific target gene promoters, such as bax. Data obtained from the analysis of p53 subcellular localization revealed that K351N mutation inhibits the nuclear export of p53 and accumulation in the cytoplasm induced by cisplatin treatment. These results identify p53 K351N as a new cancer associated mutant with reduced tumor suppressor activity and altered functions in response to apoptotic stimuli.
肿瘤抑制因子p53的失活是致癌作用以及获得对药物诱导凋亡的抗性的核心。大多数改变是错义突变，且发生在DNA结合结构域内。然而，关于四聚化结构域（TD）中的点突变却知之甚少。在此，我们研究了在顺铂耐药卵巢癌细胞系（A2780 CIS）中鉴定出的TD内一种新的p53突变体（赖氨酸351突变为天冬酰胺）的特性。我们发现K351N替代显著降低了p53四聚体的热力学稳定性，但不影响该蛋白的整体半衰期。此外，p53 K351N结合DNA以及反式激活其特定靶基因启动子（如bax）的能力降低。从p53亚细胞定位分析获得的数据显示，K351N突变抑制了顺铂处理诱导的p53核输出及在细胞质中的积累。这些结果确定p53 K351N为一种新的与癌症相关的突变体，其肿瘤抑制活性降低，且对凋亡刺激的反应功能发生改变。
