Inhibition of nuclear factor-kappaB activation is essential for membrane-associated TNF-alpha-induced apoptosis in HL-60 cells.
The killing of tumour cells that are resistant to soluble TNF-alpha (sTNF-alpha) by the membrane-bound form of TNF-alpha (mTNF-alpha) suggests that different intracellular signalling pathways are involved. We found that mTNF-alpha induced apoptosis in HL-60 cells and failed to cause degradation of inhibitor of kappa B alpha (IkappaB-alpha) and translocation and activation of nuclear factor kappa B (NF-kappaB), whereas sTNF-alpha failed to induce apoptosis, but lowered cytoplasmic inhibitor of kappa B alpha, induced translocation of NF-kappaB to the nucleus and experimentally increased activity of the regulated luciferase. Furthermore, mTNF-alpha upregulated the expression of TNF receptor associated factor (TRAF) 1 and failed to induce TRAF1 and TRAF2 membrane translocation, but led to cytoplasmic colocalization. In contrast, sTNF-alpha stimulated the expression of TRAF1 and TRAF2, recruiting both molecules onto the cell membrane poststimulation. These results suggest that the increased susceptibility of HL-60 cells to mTNF-alpha may be due to the failure of TRAF2 membrane translocation caused by the upregulation of TRAF1 expression and formation of a TRAF1/TRAF2 complex in the cytoplasm, thereby inhibiting NF-kappaB activation and inducing apoptosis.
Shi
Wenfang
W
Department of Immunology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
Li
Lingyun
L
Shi
Xu
X
Zheng
Fang
F
Zeng
Jingyang
J
Jiang
Xiaodan
X
Gong
Feili
F
Zhou
Muxiang
M
Li
Zhuoya
Z
D021581:Active Transport, Cell Nucleus / Q000502:physiology; D000818:Animals; D017209:Apoptosis / Q000276:immunology* / Q000502:physiology; D002462:Cell Membrane / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D018922:HL-60 Cells; D006801:Humans; D020672:I-kappa B Proteins / Q000378:metabolism; D051379:Mice; D016328:NF-kappa B / Q000037:antagonists & inhibitors* / Q000276:immunology / Q000378:metabolism; D041681:NIH 3T3 Cells; D047990:TNF Receptor-Associated Factor 1 / Q000378:metabolism; D047992:TNF Receptor-Associated Factor 2 / Q000378:metabolism; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*; D015854:Up-Regulation
D020672:I-kappa B Proteins; D016328:NF-kappa B; D047990:TNF Receptor-Associated Factor 1; D047992:TNF Receptor-Associated Factor 2; D014409:Tumor Necrosis Factor-alpha