【作者】 张新伟； 刁世勇； 刘航； 邢海燕； 饶青； 王敏； 王建祥；

【Author】 Zhang Xin-Wei Diao Shi-Yong Liu Hang Xing Hai-Yang Rao Qing Wang Min Wang Jian-Xiang Blood Diseases Hospital, Peking Union Medical College tianjin, 300020 Tianjin Medical University Cancer Institute and Hospital tianjin, 300060

【机构】 中国协和医科大学血液学研究所；

【摘要】 p53凋亡促进蛋白（apoptosis stimulating protein of p53,AsPP）家族抑制性成员（inhibitory member of ASPP of p53 family,iASPP）是一个新发现的p53拮抗基因,从美丽线虫到人类高度保守,在p53野生型的乳腺癌中高表达。已知iASPP至少存在2个异构体iASPP／RAI（RelA— associated inhibitor,RAI）和iASPP（828氨基酸,amino- acids,aa）。RAI最初被认为含351aa,能够与NF—kappaB 的亚单位p65（RelA）结合,抑制NF—kappaB的转录活性。进一步研究发现:RAI与ASPP家族羧基端同源,能够与p53 结合,抑制p53的促凋亡作用,因而被命名为iASPP。新近发现了一个新的iAsPP异构体,含828aa,氯基端参与胞浆定位。Western杂交发现所有细胞表达iASPP（828aa）,而无iASPP／RAI（35laa）。另外,Blast发现最初提交的RAI （NM₀06663）的开放阅读框存在移码突变。表明:iASPP／ RAI（351aa）可能并不存在或序列有错误。我们克隆出一个新的iASPP异构体,与RAI（NM₀06663）的序列相比, 有4处移码突变,但相应序列与RAI基因组序列AC092309 完全一致,翻译蛋白与iASPP蛋白序列Q8WUF5一致,具有407aa（分子量约50kDa）,羧基端含ASPP家族与p53结合所必需的锚蛋白重复和SH3域,52—407aa与iASPP（828 aa）序列CA160219的473-828完全一致。进一步研究发现iASPP（407 aa）是一个核蛋白,在细胞内与p53结合, 能够抑制p53对Bax和p21waf1启动子的促转录活性,我们命名为iASPP短型异构体（iASPP short isoform,short isoform）。更多还原

【Abstract】 Inhibitory member of the ASPP family （iASPP） is an evolutionarily conserved inhibitor of p53, and its expression is upregulated in human breast carcinomas expressing wild-type p53. iASPP at least includes two isoforms, one of iASPP/RAI（351 amino-acids, aa） and another of iASPP（828aa）. RAI was identified previously as a NF-kappaB subunit p65 （RelA） binding protein and inhibited its transcriptional activity. Further study demonstrated that iASPP/RAI shares extensively similar sequence with the C-terminal of ASPP1 and ASPP2. Moreover, iASPP/RAI is capable of binding to p53 and inhibits its ability to induce apoptosis. Accordingly, RAI also was referred to as iASPP （inhibitory member of the ASPP family）. A novel isoform of human iASPP of 828 amino acids was recently identified, which is located in both the cytoplasm and the nucleus. The N-terminus of iASPP （828aa） is required for its cytoplasmic localization. iASPP （828aa） protein is present in a range of cell lines, but iASPP/RAI is absent. Moreover, RAI open reading frame（ORF, NM₀06663）in the original report at least exists one frame-shift mutation in the BLAST research. Above-mentioned result indicates that iASPP/RAI （351aa ） protein doesn exist or its original sequence is mistake. We identify a novel isoform of human iASPP, which encodes 407aa and completely matchs with another iASPP protein sequence Q8WUF5. Although iASPP （407aa） DNA sequence exists three base pairs deletion and a single base pair insertion compared with NM.006663, it is identified with RAI genome sequence （AC092309）. iASPP （407aa） is a nuclear protein, and is capable of binding to p53 in vivo. Moreover, overexpression of iASPP （407aa ）inhibited the transcriptional activity of p53 on the promoter of both Bax and p21wafl. Hereafter, iASPP （407aa） will be refered to as iASPPS （short isoform）.更多还原