Alterations in the post-translational modification and intracellular trafficking of clusterin in MCF-7 cells during apoptosis
Alterations in the post-translational modification and intracellular trafficking of clusterin in MCF-7 cells during apoptosis
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DOI：
10.1038/sj.cdd.4401254
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发表时间：
2003-08-01
影响因子：
12.4
通讯作者：
Tenniswood, M
中科院分区：
文献类型：
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作者：
O'Sullivan, J;Whyte, L;Tenniswood, M
异源二聚体二硫键连接的70-80 kDa糖蛋白，在大多数（如果不是全部）上皮依赖性上皮组织消退期间诱导。这些研究描述了用抗雌激素和TNF α诱导MCF-7细胞凋亡之前和之后丛生蛋白的生物发生和细胞内运输。在生理条件下，丛生蛋白在内质网（ER）中被修饰，并在高尔基体中被蛋白水解切割以在分泌之前产生离散的α和β链。用TNF α或抗雌激素ICI 182，780处理，诱导MCF-7细胞凋亡，并导致高尔基体驻留酶活性的实质性变化，显著改变丛生蛋白的生物发生。这导致出现聚集在细胞核中的50-53 kDa未裂解的、非糖基化的、二硫键连接的簇蛋白同种型。虽然丛生蛋白含有一个神秘的SV-40样的核定位信号，该序列的突变不影响二硫键连接的核异构体的核积累。共聚焦显微镜观察表明，丛生蛋白在细胞核内的聚集与DNA断裂是一致的。这些数据表明，至少在分泌性上皮细胞中，从高尔基体到ER的非糖基化的，未裂解的异构体的逆行运输和随后的易位丛生蛋白的细胞核中发生在垂死的细胞。
Clusterin is a heterodimeric, disulfide-linked 70-80 kDa glycoprotein that is induced during regression of most, if not all, hormone-dependent epithelial tissues. These studies describe the biogenesis and intracellular trafficking of clusterin in MCF-7 cells before and after the initiation of apoptosis with antiestrogens and TNFalpha. Under physiological conditions, clusterin is modified in the endoplasmic reticulum ( ER), and proteolytically cleaved in the Golgi to generate discrete alpha and beta chains prior to secretion. Treatment with TNFalpha or the antiestrogen, ICI 182,780, induces apoptosis in MCF-7 cells and leads to substantial changes in the activity of Golgi-resident enzymes, significantly altering the biogenesis of clusterin. This leads to the appearance of a 50-53 kDa uncleaved, nonglycosylated, disulfide-linked isoform of clusterin that accumulates in the nucleus. While clusterin contains a cryptic SV-40-like nuclear localization signal, mutation of this sequence does not affect the nuclear accumulation of the disulfide-linked nuclear isoform. Confocal microscopy demonstrates that the nuclear accumulation of clusterin is coincident with DNA fragmentation. These data suggest that, at least in secretory epithelial cells, retrograde transport from the Golgi to the ER of a nonglycosylated, uncleaved isoform and the subsequent translocation of clusterin to the nucleus occur in dying cells.