突变体p53研究进展

抑癌基因突变是癌症发生过程中一个极为关键的事件。p53作为体内最重要的抑癌基因之一, 在人类癌症中发生突变的频率高达50%。同时, p53突变也是人类遗传病Li-Fraumeni综合征的主要病因。p53最常见的突变形式是错义突变, 所形成的突变体p53不但失去了野生型p53的抑癌功能, 而且还获得了一系列类似于癌基因的功能, 促进了肿瘤的进程。文章拟对突变体p53的结构功能改变, 获得癌基因活性的分子机制, 以及近年来对封闭突变体p53活性所进行的探索等研究方向所取得的进展做一综述。     

p53与细胞死亡

p53是一种重要的肿瘤抑制因子,是迄今发现与人类肿瘤相关性最高的分子之一。超过50%的人类肿瘤含有p53基因突变。因此,p53是肿瘤治疗中的重要分子靶点。p53依赖的细胞凋亡是其抑制肿瘤的重要机制之一。然而,最近研究发现,p53不仅参与细胞凋亡,还与程序性细胞坏死、细胞自噬以及铁诱导的细胞死亡等细胞死亡途径相关。促使肿瘤细胞死亡是肿瘤治疗的重要目标。因此,进一步了解p53与细胞死亡之间的关系,将有助于探索以p53为靶点的肿瘤治疗和p53相关肿瘤细胞耐药机制。     

p53家族新成员：p51

p53是一种广谱的肿瘤抑制基因,其新家族成员p51具有同p53相似的DNA结合特笥和相似的功能,同样可以转录激活p53基因的内源性靶分子,如细胞周期抑制基因p21、导致细胞凋亡和生长受抑。本文阐述了它的研究进展。     

甲状腺肿瘤p53mRNA及p53蛋白表达的研究

本文采用原位杂交法、免疫组织化学方法分别检测了甲状腺癌ｐ５３ｍＲＮＡ、ｐ５３蛋白的表达,结果显示：２０例甲状腺癌ｐ５３ｍＲＮＡ、ｐ５３蛋白均呈阳性反应,８例甲状腺瘤仅１例呈弱阳性反应,８例Ｇｒａｖｅｓ病全部呈阴性反应。细胞质和细胞核ｍＲＮＡ、ｐ５３蛋白灰度检测发现,甲状腺瘤细胞质、核ｐ５３ｍＲＮＡ灰度值和ｐ５３蛋白灰度值均明显高于Ｇｒａｖｅｓ病,而甲状腺癌其细胞质、核ｐ５３ｍＲＮＡ灰度值和ｐ５３蛋白灰度值又明显高于良性甲状腺瘤,提示甲状腺癌ｐ５３ｍＲＮＡ和ｐ５３蛋白的高表达可能与甲状腺肿瘤细胞分化程度有关     

Influenza A viruses control expression of proviral human p53 isoforms p53β and Delta133p53α

Previous studies have described the role of p53 isoforms, including p53β and Δ133p53α, in the modulation of the activity of full-length p53, which regulates cell fate. In the context of influenza virus infection, an interplay between influenza viruses and p53 has been described, with p53 being involved in the antiviral response. However, the role of physiological p53 isoforms has never been explored in this context. Here, we demonstrate that p53 isoforms play a role in influenza A virus infection by using silencing and transient expression strategies in human lung epithelial cells. In addition, with the help of a panel of different influenza viruses from different subtypes, we also show that infection differentially regulates the expressions of p53β and Δ133p53α. Altogether, our results highlight the role of p53 isoforms in the viral cycle of influenza A viruses, with p53β and Δ133p53α acting as regulators of viral production in a p53-dependent manner.     

p53与细胞周期调控

p53蛋白首先在SV-40转染的小鼠细胞中发现,继之在不同类型的转化细胞系中也被检测到。进一步研究证明它还存在于正常细胞和组织中,但与转化细胞相比其含量要低得多。 1988年Levine和Oren等报道了第一个被鉴定的p53突变型p53 Vall 35。以后,人们在转化细胞中检测到各种类型的p53突变型。为了有效地研究p53蛋白,已发展了很多识别p53蛋白的单克隆抗体,其中有的具有种     

p53与癌症治疗

p53蛋白是一种重要的肿瘤抑制蛋白,它可以诱导肿瘤细胞生长停滞、衰老以及程序化死亡.由于它在癌细胞抑制中的至关重要作用,因而目前关于癌症的治疗大多数都是直接或间接通过调控p53蛋白来实现的.文中主要介绍了近几年来p53蛋白在理论和临床上最新的研究进展.     

Protein Interaction Between p53 and △113p53 Is Required for the Anti-Apoptotic Function of △113p53

Zebrafish △113p53, an N-terminal truncated p53 isoform, is a p53-target gene that antagonises p53-mediated apoptotic activity.Interestingly, △113p53 does not act on p53 in a dominant-negative manner, but rather interferes with the p53 function by differentially modulating p53-target gene expression to protect cells from apoptosis. Previous studies showed that over-expressed △113p53 and p53proteins formed a complex. However, it is not known whether endogenous p53 and △113p53 proteins also interact with each other, and if this interaction is required for △113p53 to inhibit the apoptotic activity of full-length p53. In this study, we used two available zebrafish p53 antibodies to address these questions. One, Zfp53-N, only recognises full-length p53, whereas the other, Zfp53-A7C10, detects both full-length p53 and △113p53. Using Zfp53-N for immunoprecipitation and Zfp53-A7C10 for detection, we demonstrated that endogenous △113p53 and full-length p53 induced by a DNA-damaging drug formed a complex in vivo. Furthermore, of the six △113p53 mutants we generated with different point mutations in the oligomerisation domain, two failed to interact with p53 and lost the ability to modulate p53-target gene expression and inhibit p53-induced cell apoptosis. However, those △113p53 mutants that could interact with p53 retained the ability to antagonise the apoptotic activity of p53. Therefore, our data demonstrated that proteineprotein interaction between △113p53and p53 is essential for the anti-apoptotic function of △113p53. In addition, the two △113p53 mutants that failed to interact with p53 are also useful for the study of the mechanisms of other functions of △113p53.     

Protein Interaction Between p53 and △113p53 Is Required for the Anti-Apoptotic Function of △113p53

Zebrafish △113p53, an N-terminal truncated p53 isoform, is a p53-target gene that antagonises p53-mediated apoptotic activity. Interestingly, △113p53 does not act on p53 in a dominant-negative manner, but rather interferes with the p53 function by differentially modulating p53-target gene expression to protect cells from apoptosis. Previous studies showed that over-expressed △113p53 and p53 proteins formed a complex. However, it is not known whether endogenous p53 and △113p53 proteins also interact with each other, and if this interaction is required for △113p53 to inhibit the apoptotic activity of full-length p53. In this study, we used two available zebrafish p53 antibodies to address these questions. One, Zfp53-N, only recognises full-length p53, whereas the other, Zfp53-A7C10, detects both full-length p53 and △113p53. Using Zfp53-N for immunoprecipitation and Zfp53-A7C 10 for detection, we demonstrated that endogenous △113p53 and full-length p53 induced by a DNA-damaging drug formed a complex in vivo. Furthermore, of the six △113p53 mutants we generated with different point mutations in the oligomerisation domain, two failed to interact with p53 and lost the ability to modulate p53-target gene expression and inhibit p53-induced cell apoptosis. However, those △113p53 mutants that could interact with p53 retained the ability to antagonise the apoptotic activity of p53. Therefore, our data demonstrated that protein--protein interaction between △113p53 and p53 is essential for the anti-apoptotic function of △113p53. In addition, the two △113p53 mutants that failed to interact with p53 are also useful for the study of the mechanisms of other functions of △113p53.     

p53与肿瘤治疗

p53是目前发现的与人类肿瘤发病相关性最大的抑癌基因之一。野生型p53参与DNA损伤修复、细胞周期调控、细胞凋亡及抑制血管生成等。p53基因的突变会使上述功能丧失,从而导致肿瘤的形成。随着分子生物学技术的发展,对肿瘤抑制基因p53的研究越来越深入。本文综合近年来国内外的研究进展,就p53与肿瘤形成的关系及其在肿瘤治疗中的应用等作一综述。     

p53肿瘤抑制基因

正常细胞的增殖常取决于促进生长的原癌基因和抑制生长的肿瘤抑制基因的平衡调节。原癌基因的激活或者肿瘤抑制基因的失活都能导致细胞生长的失控。事实上,许多肿瘤的发生需要基因组中这两类基因的同时突变。虽然人们对肿瘤抑制基因的认识较细胞癌基因晚了近10年,但当今它已成为了解肿瘤起源分子     

激发p53对癌症开战

有时被称为“基因组守护神”的肿瘤抑制蛋白p53，针对DNA损伤发生反应，要么停止细胞分裂，要么促使细胞凋亡。p53的反应通过阻止已发生恶性突变的细胞不停的生长，从而阻断肿瘤的结构形成。但是p53自身也对损伤敏感，这一点被认为利于半数癌症的生长，包括常见的一些癌症，如皮肤癌、乳腺癌和结肠癌。现在，研究人员已鉴定了一种药物，能够保留一些变异的P53蛋白的正常功能，因此可能开辟出一条新的治疗癌症的方法。     

p53选择性抗瘤腺病毒

多种肿瘤的抑癌基因p53发生了突变。一种腺病毒E1B缺失体ONYX-015能够在p53突变的肿瘤细胞内有效地复制而导致痛细胞的裂解,但不能在p53正常的细胞内复制。这种p53选择性抗瘤病毒代表了一类新的抗癌武器:溶癌病毒。     

p53-mediated induction of Noxa and p53AIP1 requires NFκB

The intricate regulation of cell survival and cell death is critical for the existence of both normal and transformed cells. Two factors central to these processes are p53 and NFκB, with both factors having ascribed roles in both promoting and repressing cell death. Not surprisingly, a number of studies have previously reported interplay between p53 and NFκB. The mechanistic basis behind these observations, however, is currently incomplete. We report here further insights into this interplay using a system where blockade of NFκB inhibits cell death from p53, but at the same time sensitizes cells to death by TNFα. We found in agreement with a recent report showing that NFκB is required for the efficient activation of the BH3-only protein Noxa by the p53 family member p73, that p53’s ability to induce Noxa is also impeded by inhibition of NFκB. In contrast to the regulation by p73, however, blockade of NFκB downstream of p53 decreases Noxa protein levels without effects on Noxa mRNA. Our further analysis of the effects of NFκB inhibition on p53 target gene expression revealed that while most target genes analysed where unaffected by blockade of NFκB, the p53-mediated induction of the pro-apoptotic gene p53AIP1 was significantly dependent on NFκB. These studies therefore add further insight into the complex relationship of p53 and NFκB and since both Noxa and p53AIP1 have been shown to be important components of p53-mediated cell death responses, these findings may also indicate critical points where NFκB plays a pro-apoptotic role downstream of p53.     

转化相关蛋白——p53

p53是一种细胞蛋白,在许多种转化细胞、肿瘤细胞甚至一些正常细胞中,其含量显著增高。它是一种磷蛋白,能与病毒编码的某些蛋白形成复合物,并具有抗原性。它的基因位于第11对(小鼠)和第17对(人)染色体上。这一蛋白与细胞转化、肿瘤发生发展、以及正常细胞生长都密切相关。有人把p53归入了癌基因家族中myc等核蛋白类。     

p53调控骨关节炎软骨细胞凋亡

肿瘤抑制蛋白p53是一种可以有效调节哺乳动物细胞生长的核磷酸化蛋白质。p53表达增加能够激活一系列细胞基因,通过抑制多个细胞周期蛋白依赖性激酶导致细胞周期停滞并凋亡。有研究表明,骨关节炎(osteoarthritis,OA)软骨细胞中,p53的表达高于正常软骨细胞,通过下调p53表达能够减少软骨细胞凋亡,进而预防和缓解骨关节炎病变,这可能与线粒体凋亡途径密切相关,但是具体机制尚不明确。本文通过综述近年来p53调控骨关节炎软骨细胞凋亡的文献资料,为骨关节炎机制和治疗有关研究提供理论基础。     

通过血流进行p53基因治疗

美国加利福尼亚-旧金山大学(旧金山,加州)和Schering-Plough研究所(凯尼尔沃思,新泽西)的研究者报道了若干项有希望的研究结果,即通过血流对肝癌患者进行p53基因治疗的I期实验结果良好.