Evidence for serpinB2-independent protection from TNF-alpha-induced apoptosis.
Clade B serine proteinase inhibitors (serpins) are intracellular proteins, whereas most of their identified targets are extracellular. A proposed intracellular role for these inhibitors is protection from apoptosis. We investigated the contribution of serpinB2 (plasminogen activator inhibitor-2, PAI-2) activity in TNF-alpha-induced apoptosis. PAI-2 is expressed in many normal and transformed cell types, particularly after stimulation with inflammatory cytokines. PAI-2 has been linked to protection from TNF-alpha-induced apoptosis, and a stabilizing interaction with the retinoblastoma protein (Rb1) has been proposed. We examined the activity of PAI-2 in TNF-alpha-induced apoptosis using HeLa, Isreco-1 and HT1080 cell lines. Stimulation with TNF-alpha protected each cell type from apoptosis induced by TNF-alpha and cycloheximide. Protection correlated with an increase in PAI-2 expression in IS-1 and HT1080 cells but not in HeLa cells where PAI-2 mRNA and protein were undetectable. PAI-2 was overexpressed in each cell type but gave no protection from TNF-alpha-induced apoptosis measured by cell viability, annexinV binding and caspase-3/7 activity. We detected wild-type Rb1, unchanged TNF receptor levels and induction of other apoptosis-protective factors in all cell types. In conclusion, elevated PAI-2 levels do not protect cells from TNF-alpha-induced apoptosis, and the protective effect of prior stimulation with TNF-alpha does not require PAI-2.
Fish
Richard J
RJ
Division of Angiology and Haemostasis, Department of Internal Medicine, Geneva University Hospital, 24 Rue Micheli-du-Crest, CH-1205, Geneva, Switzerland. Richard.Fish@medecine.unige.ch
Kruithof
Egbert K O
EK
D048868:Adaptor Proteins, Signal Transducing; D017304:Annexin A5 / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D020169:Caspases / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects; D003110:Colonic Neoplasms / Q000188:drug therapy / Q000378:metabolism*; D003513:Cycloheximide / Q000494:pharmacology; D004268:DNA-Binding Proteins; D005354:Fibrosarcoma / Q000188:drug therapy / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D016086:Lentivirus / Q000235:genetics; D016297:Mutagenesis, Site-Directed; D009154:Mutation / Q000235:genetics; D009687:Nuclear Proteins; D017396:Plasminogen Activator Inhibitor 2 / Q000235:genetics / Q000378:metabolism*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D011506:Proteins / Q000378:metabolism; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000378:metabolism; D016160:Retinoblastoma Protein / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000378:metabolism; D014407:Tumor Cells, Cultured; D000072598:Tumor Necrosis Factor alpha-Induced Protein 3; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D048868:Adaptor Proteins, Signal Transducing; D017304:Annexin A5; D004268:DNA-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; D009687:Nuclear Proteins; D017396:Plasminogen Activator Inhibitor 2; D011500:Protein Synthesis Inhibitors; D011506:Proteins; D047888:Receptors, Tumor Necrosis Factor, Type I; D016160:Retinoblastoma Protein; C434062:TNIP2 protein, human; D014157:Transcription Factors; D014409:Tumor Necrosis Factor-alpha; D003513:Cycloheximide; C076529:TNFAIP3 protein, human; D000072598:Tumor Necrosis Factor alpha-Induced Protein 3; D020169:Caspases