title: STAT1 mediates transmembrane TNF-alpha-induced formation of death-inducing signaling complex and apoptotic signaling via TNFR1.
abstract: Tumor necrosis factor-alpha (TNF-α) exists in two forms: secretory TNF-α (sTNF-α) and transmembrane TNF-α (tmTNF-α). Although both forms of TNF-α induce tumor cell apoptosis, tmTNF-α is able to kill tumor cells that are resistant to sTNF-α-mediated cytotoxicity, indicating their differences in signal transduction. Here, we demonstrate that internalization of TNFR1 is crucial for sTNF-α- but not for tmTNF-α-induced apoptosis. sTNF-α induces binding of tumor necrosis factor receptor type 1-associated death domain protein (TRADD) to the death domain (DD) of TNFR1 and subsequent activation of nuclear factor kappa B (NF-κB), and the formation of death-inducing signaling complexes (DISCs) in the cytoplasm after internalization. In contrast, tmTNF-α induces DISC formation on the membrane in a DD-independent manner. It leads to the binding of signal transducer and activator of transcription 1 (STAT1) to a region spanning amino acids 319-337 of TNFR1 and induces phosphorylation of serine at 727 of STAT1. The phosphorylation of STAT1 promotes its binding to TRADD, and thus recruits Fas-associated protein with DD (FADD) and caspase 8 to form DISC complexes. This STAT1-dependent signaling results in apoptosis but not NF-κB activation. STAT1-deficiency in U3A cells counteracts tmTNF-α-induced DISC formation and apoptosis. Conversely, reconstitution of STAT1 expression restores tmTNF-α-induced apoptotic signaling in the cell line. Consistently, tmTNF-α suppresses the growth of STAT1-containing HT1080 tumors, but not of STAT1-deficient U3A tumors in vivo. Our data reveal an unappreciated molecular mechanism of tmTNF-α-induced apoptosis and may provide a new clue for cancer therapy.
authors.affiliation: Department of Immunology, Basic Medical School, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, PR China.
authors.forename: Yaping
authors.initials: Y
authors.lastname: Jiang
authors.affiliation: Department of Immunology, Basic Medical School, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, PR China.|Department of General Surgery, Xinqiao Hospital, Third Military Medical University, Chongqing, PR China.
authors.forename: Min
authors.initials: M
authors.lastname: Yu
authors.affiliation: Department of Immunology, Basic Medical School, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, PR China.
authors.forename: Xuena
authors.initials: X
authors.lastname: Hu
authors.affiliation: Department of Immunology, Basic Medical School, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, PR China.
authors.forename: Lu
authors.initials: L
authors.lastname: Han
authors.affiliation: Department of Immunology, Basic Medical School, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, PR China.
authors.forename: Kun
authors.initials: K
authors.lastname: Yang
authors.affiliation: Department of Immunology, Basic Medical School, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, PR China.
authors.forename: Hongping
authors.initials: H
authors.lastname: Ba
authors.affiliation: Department of Immunology, Basic Medical School, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, PR China.
authors.forename: Zunyue
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Department of Immunology, Basic Medical School, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, PR China.
authors.forename: Bingjiao
authors.initials: B
authors.lastname: Yin
authors.affiliation: Department of Immunology, Basic Medical School, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, PR China.
authors.forename: Xiang-Ping
authors.initials: XP
authors.lastname: Yang
authors.affiliation: Department of Immunology, Basic Medical School, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, PR China.
authors.forename: Zhuoya
authors.initials: Z
authors.lastname: Li
authors.affiliation: Department of Immunology, Basic Medical School, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, PR China.
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
mesh_terms: D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002103:Cadaverine / Q000031:analogs & derivatives / Q000494:pharmacology; D053181:Caspase 8 / Q000378:metabolism; D002460:Cell Line; D053418:Death Domain Receptor Signaling Adaptor Proteins / Q000378:metabolism*; D053200:Fas-Associated Death Domain Protein / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism; D041681:NIH 3T3 Cells; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D050794:STAT1 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D053199:TNF Receptor-Associated Death Domain Protein / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism* / Q000633:toxicity
chemical_list: D000590:Amino Acid Chloromethyl Ketones; D053418:Death Domain Receptor Signaling Adaptor Proteins; D053200:Fas-Associated Death Domain Protein; D016328:NF-kappa B; D047888:Receptors, Tumor Necrosis Factor, Type I; D050794:STAT1 Transcription Factor; D053199:TNF Receptor-Associated Death Domain Protein; D014409:Tumor Necrosis Factor-alpha; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D053181:Caspase 8; C008542:monodansylcadaverine; D002103:Cadaverine