TNF-alpha-induced cell death in feline immunodeficiency virus-infected cells is mediated by the caspase cascade.
TNF-alpha induced apoptosis in a feline fibroblastic cell line (CRFK) infected with FIV but not in its uninfected control. In this study, to understand the molecular basis of the different susceptibilities to TNF-alpha between FIV-infected and uninfected cells, we examined the expression of TNF receptors and the activation of the caspase and NF-kappaB pathways. Expression levels of TNFR I and TNFR II mRNAs were similar between uninfected and FIV-infected CRFK cells. To understand the role of caspases in TNF-alpha-induced apoptosis, we examined the effect of three different classes of caspase inhibitors, Z-VAD-FMK, Ac-YVAD-CMK, and Z-DEVD-FMK, on the TNF-alpha-induced apoptosis in FIV-infected cells. Pretreatment with each of these caspase inhibitors protected FIV-infected CRFK cells from TNF-alpha-induced cell death. Moreover, one of the caspase substrates, poly(ADP-ribose) polymerase, was shown to be cleaved after TNF-alpha treatment in FIV-infected CRFK cells but not in uninfected CRFK cells. Electrophoretic mobility shift assay using an NF-kappaB motif oligonucleotide and promoter assay using an NF-kappaB luciferase reporter construct indicated that TNF-alpha treatment had induced activation of NF-kappaB in both FIV-infected and uninfected CRFK cells. The present study indicates that TNF-alpha-induced apoptosis in FIV-infected CRFK cells is mediated by the activation of the caspase cascade, but not by either upregulation of TNF receptor or inhibition of NF-kappaB.
Mizuno
T
T
Department of Veterinary Internal Medicine, Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
Goto
Y
Y
Baba
K
K
Masuda
K
K
Ohno
K
K
Tsujimoto
H
H
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism*; D002415:Cats; D002478:Cells, Cultured; D003513:Cycloheximide / Q000494:pharmacology; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D004347:Drug Interactions; D005347:Fibroblasts / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology / Q000821:virology; D016089:Immunodeficiency Virus, Feline / Q000502:physiology*; D016328:NF-kappa B / Q000378:metabolism; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D018124:Receptors, Tumor Necrosis Factor / Q000096:biosynthesis / Q000235:genetics; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D000590:Amino Acid Chloromethyl Ketones; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D016328:NF-kappa B; D011500:Protein Synthesis Inhibitors; D018124:Receptors, Tumor Necrosis Factor; D014409:Tumor Necrosis Factor-alpha; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D003609:Dactinomycin; D003513:Cycloheximide; D011065:Poly(ADP-ribose) Polymerases; D020169:Caspases