Cytoplasmic aggregation of TRAF2 and TRAF5 proteins in the Hodgkin-Reed-Sternberg cells
Cytoplasmic aggregation of TRAF2 and TRAF5 proteins in the Hodgkin-Reed-Sternberg cells
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DOI：
10.1016/s0002-9440(10)61112-1
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发表时间：
2002-05-01
影响因子：
6
通讯作者：
Watanabe, T
中科院分区：
文献类型：
--
作者：
Horie, R;Watanabe, T;Watanabe, T
我们先前报道，在Hodgkin-Reed-Sternberg(H-RS)细胞中高表达CD30的非配体依赖的信号转导是导致NF-kappaB结构性激活的原因。在本研究中，我们研究了肿瘤坏死因子受体相关因子(TRAF)蛋白在H-RS细胞内的定位。共聚焦免疫荧光显微镜观察H-RS细胞株和高表达CD30的HEK293转化子，发现TRAF2和TRAF5聚集在细胞质中，并聚集在细胞膜附近。相反，在与霍奇金病(HD)无关的细胞系和对照HEK293细胞中，TRAF蛋白弥漫分布于细胞浆中。此外，TRAF蛋白在HD淋巴结的H-RS细胞中有相同的细胞内分布，而在非霍奇金淋巴瘤的淋巴组织中则不表达。显性阴性的TRAF2和TRAF5抑制H-RS细胞的胞浆聚集和组成性的核因子-kappaB的激活。共聚焦免疫荧光显微镜还显示，在H-RS细胞系中，IKKalpha、Nik和IkappaBalpha与聚集的TRAF蛋白共定位。这些结果表明，TRAF蛋白聚集参与了CD30高表达的信号传递过程，并提示它们作为支架蛋白发挥作用。因此，TRAF蛋白的细胞质聚集似乎反映了构成CD30信号的H-RS细胞的特征。
We previously reported that ligand-independent signaling by highly expressed CD30 in Hodgkin-Reed-Sternberg (H-RS) cells is responsible for constitutive activation of NF-kappaB. In the present study, we characterize the intracellular localization of tumor necrosis factor (TNF) receptor associated factor (TRAF) proteins in H-RS cells. Confocal immunofluorescence microscopy of cell lines derived from H-RS cells and HEK293 transformants highly expressing CD30 revealed aggregation of TRAF2 and TRAF5 in the cytoplasm as well as clustering near the cell membrane. In contrast, TRAF proteins were diffusely distributed in the cytoplasm in cell lines unrelated to Hodgkin's disease (HD) and control HEK293 cells. Furthermore, the same intracellular distribution of TRAF proteins was demonstrated in H-RS cells of lymph nodes of HD, but not in lymphoma cells in lymph nodes of non-Hodgkin's lymphoma. Dominant-negative TRAF2 and TRAF5 suppressed cytoplasmic aggregation along with constitutive NF-kappaB activation in H-RS cell lines. Confocal immunofluorescence microscopy also revealed co-localization of IKKalpha, NIK, and IkappaBalpha with aggregated TRAF proteins in H-RS cell lines. These results suggest involvement of TRAF protein aggregation in the signaling process of highly expressed CD30 and suggest they function as scaffolding proteins. Thus, cytoplasmic aggregation of TRAF proteins appears to reflect constitutive CD30 signaling which is characteristic of H-RS cells.