The zinc finger protein A20 interacts with a novel anti-apoptotic protein which is cleaved by specific caspases.
A20 is a Cys2/Cys2 zinc finger protein which is induced by a variety of inflammatory stimuli and which has been characterized as an inhibitor of cell death by a yet unknown mechanism. In order to clarify its molecular mechanism of action, we used the yeast two-hybrid system to screen for proteins that interact with A20. A cDNA fragment was isolated which encoded a portion of a novel protein (TXBP151), which was recently found to be a human T-cell leukemia virus type-I (HTLV-I) Tax-binding protein. The full-length 2386 bp TXBP151 mRNA encodes a protein of 86 kDa. Like A20, overexpression of TXBP151 could inhibit apoptosis induced by tumour necrosis factor (TNF) in NIH3T3 cells. Moreover, transfection of antisense TXBP151 partially abolished the anti-apoptotic effect of A20. Furthermore, apoptosis induced by TNF or CD95 (Fas/APO-1) was associated with proteolysis of TXBP151. This degradation could be inhibited by the broad-spectrum caspase inhibitor zVAD-fmk or by expression of the cowpox virus-derived inhibitor CrmA, suggesting that TXBP151 is a novel substrate for caspase family members. TXBP151 was indeed found to be specifically cleaved in vitro by members of the caspase-3-like subfamily, viz. caspase-3, caspase-6 and caspase-7. Thus TXBP151 appears to be a novel A20-binding protein which might mediate the anti-apoptotic activity of A20, and which can be processed by specific caspases.
De Valck
D
D
Department of Molecular Biology, Flanders Interuniversity Institute for Biotechnology and University of Gent, Belgium.
Jin
D Y
DY
Heyninck
K
K
Van de Craen
M
M
Contreras
R
R
Fiers
W
W
Jeang
K T
KT
Beyaert
R
R
D016475:3T3 Cells; D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001483:Base Sequence; D002352:Carrier Proteins / Q000302:isolation & purification / Q000378:metabolism*; D020169:Caspases / Q000378:metabolism*; D002460:Cell Line; D003001:Cloning, Molecular; D003546:Cysteine Endopeptidases; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D018076:DNA, Complementary / Q000235:genetics; D004268:DNA-Binding Proteins; D003609:Dactinomycin / Q000494:pharmacology; D005796:Genes; D006367:HeLa Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D051379:Mice; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D011506:Proteins / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics; D015843:Serpins / Q000502:physiology; D013379:Substrate Specificity; D014162:Transfection; D000072598:Tumor Necrosis Factor alpha-Induced Protein 3; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D014764:Viral Proteins; D016335:Zinc Fingers; D019014:fas Receptor / Q000502:physiology
D000590:Amino Acid Chloromethyl Ketones; D002352:Carrier Proteins; D015853:Cysteine Proteinase Inhibitors; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D019384:Nucleic Acid Synthesis Inhibitors; D016376:Oligonucleotides, Antisense; D011506:Proteins; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D015843:Serpins; C120635:TAX1BP1 protein, human; D014409:Tumor Necrosis Factor-alpha; D014764:Viral Proteins; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D019014:fas Receptor; D003609:Dactinomycin; C074641:interleukin-1beta-converting enzyme inhibitor; C076529:TNFAIP3 protein, human; D000072598:Tumor Necrosis Factor alpha-Induced Protein 3; D020169:Caspases; D003546:Cysteine Endopeptidases; C513261:Tnfaip3 protein, mouse