Cytoplasmic aggregation of TRAF2 and TRAF5 proteins in the Hodgkin-Reed-Sternberg cells.
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-kappa B. 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-kappa B activation in H-RS cell lines. Confocal immunofluorescence microscopy also revealed co-localization of IKK alpha, NIK, and I kappa B alpha 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.
Horie
Ryouichi
R
Division of Pathology, Department of Cancer Research, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan.
Watanabe
Takuro
T
Ito
Kinji
K
Morisita
Yasuyuki
Y
Watanabe
Mariko
M
Ishida
Takaomi
T
Higashihara
Masaaki
M
Kadin
Marshall
M
Watanabe
Toshiki
T
D002460:Cell Line; D003593:Cytoplasm / Q000378:metabolism; D003902:Detergents; D005786:Gene Expression Regulation; D018922:HL-60 Cells; D006689:Hodgkin Disease / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D051550:I-kappa B Kinase; D020672:I-kappa B Proteins / Q000378:metabolism; D007150:Immunohistochemistry; D019169:Jurkat Cells; D020014:K562 Cells; D017730:Ki-1 Antigen / Q000235:genetics / Q000378:metabolism; D018613:Microscopy, Confocal; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011506:Proteins / Q000378:metabolism*; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism; D016539:Reed-Sternberg Cells / Q000737:chemistry / Q000473:pathology*; D015398:Signal Transduction; D012995:Solubility; D013347:Subcellular Fractions / Q000737:chemistry; D047992:TNF Receptor-Associated Factor 2; D048015:TNF Receptor-Associated Factor 5; D014407:Tumor Cells, Cultured; D020298:U937 Cells; D000097782:NF-kappaB-Inducing Kinase
D003902:Detergents; D051550:I-kappa B Kinase; D020672:I-kappa B Proteins; D017730:Ki-1 Antigen; D016328:NF-kappa B; D017346:Protein Serine-Threonine Kinases; D011506:Proteins; D018124:Receptors, Tumor Necrosis Factor; D047992:TNF Receptor-Associated Factor 2; D048015:TNF Receptor-Associated Factor 5; D000097782:NF-kappaB-Inducing Kinase; C496559:CHUK protein, human; C496560:IKBKB protein, human; C496565:IKBKE protein, human