Human α2,3-sialyltransferase (ST3Gal II) is a stage-specific embryonic antigen-4 synthase
Human α2,3-sialyltransferase (ST3Gal II) is a stage-specific embryonic antigen-4 synthase
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DOI：
10.1074/jbc.m213223200
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发表时间：
2003-07-18
影响因子：
4.8
通讯作者：
Miyagi, T
中科院分区：
文献类型：
--
作者：
Saito, S;Aoki, H;Miyagi, T
单唾液酸五糖基神经酰胺（MGb 5），最初被描述为阶段特异性胚胎抗原-4，在睾丸生殖细胞肿瘤和人肾细胞癌（RCC）的侵袭性病例中表达。阐明MSGb 5合成调控的分子机制对于理解睾丸癌的发生和人类肾细胞癌的恶性进展是非常重要的。为此目的，我们研究了参与MSGb 5合成的α 2，3-唾液酸转移酶。我们采用表达克隆结合聚合酶链反应的方法，从肾癌细胞系ACHN文库中分离到一个cDNA克隆。发现克隆的cDNA在序列上与先前克隆的ST 3Gal II相同。在COS-1细胞中，该蛋白质的可溶性重组形式显示出除去唾液酸-GM 1和GM 1a外，α 2，3-唾液酸转移酶对globopentaosylceramide（Gb 5）的酶活性。瞬时转染COS-7和ACHN细胞与此cDNA诱导MSGb 5的增加，而稳定转染反义ST 3Gal II cDNA抑制ACHN细胞中MSGb 5的表达。在8个RCC细胞系中的7个和手术获得的所有6个RCC组织中，ST 3Gal II mRNA水平增加，尽管它不一定与RCC细胞系中的MSGb 5水平一致。这项研究表明，ST 3Gal II是MSGb 5（阶段特异性胚胎抗原-4）合酶，其表达水平的增加与肾癌的发生密切相关。
Monosialosyl globopentaosylceramide (MSGb5), originally described as stage-specific embryonic antigen-4, is expressed in testicular germ cell tumors and in aggressive cases of human renal cell carcinoma (RCC). Clarification of the molecular mechanisms regulating synthesis of MSGb5 is very important to understand testicular carcinogenesis and the malignant progression of human RCC. For this purpose, we have investigated alpha2,3-sialyltransferase involved in the synthesis of MSGb5. We used the method of expression cloning combined with polymerase chain reaction targeted to sialylmotif to isolate a cDNA clone from RCC cell line ACHN library. The cloned cDNA was found to be identical to the previously cloned ST3Gal II in sequence. A soluble recombinant form of the protein in COS-1 cells showed an enzyme activity of alpha2,3-sialyltransferase toward globopentaosylceramide (Gb5) in addition to asialo-GM1 and GM1a. Transient transfection of COS-7 and ACHN cells with this cDNA induced an increase of MSGb5, whereas stable transfection of antisense ST3Gal II cDNA suppressed expression of MSGb5 in ACHN cells. The ST3Gal II mRNA level was increased in 7 of 8 RCC cell lines and in all six RCC tissues surgically obtained, although it was not necessarily consistent with the MSGb5 level in RCC cell lines. This study indicates that ST3Gal II is a MSGb5 (stage-specific embryonic antigen-4) synthase and that its increased expression level is closely related to renal carcinogenesis.