The HPV-16 E5 protein inhibits TRAIL- and FasL-mediated apoptosis in human keratinocyte raft cultures.
By using raft cultures of the polyclonal HaCaT cell lines stably transfected either with E5 (HaCaT/E5) or the empty vector (HaCaT/pMSG) as reference, we investigated the effect of the human papillomavirus type 16 (HPV-16) E5 protein on apoptosis. In comparison to conventional monolayer cultures this model system allows analysis of apoptosis under more tissue-like conditions by mimicking the stratified organization of a normal surface epithelium. Apoptosis was triggered either by FasL or TRAIL. Execution of the death program was checked at early and late stages by monitoring procaspase-3 cleavage and DNA fragmentation, respectively. Rafts of E5-expressing keratinocytes were completely protected from apoptosis and showed a background of apoptotic cells as low as the untreated cultures. In contrast, the HaCaT/pMSG cultures revealed a dramatic increase in apoptotic cells upon ligand treatment throughout the epithelial compartment. We conclude that the presence of the HPV-16 E5 protein in our tissue-like model prevents FasL- or TRAIL-mediated apoptosis.
Kabsch
Kirsten
K
German Cancer Research Center, University of Heidelberg, Heidelberg, Germany.
Mossadegh
Nina
N
Kohl
Annette
A
Komposch
Gerda
G
Schenkel
Johannes
J
Alonso
Angel
A
Tomakidi
Pascal
P
D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins; D053148:Caspase 3; D020169:Caspases / Q000502:physiology; D002478:Cells, Cultured; D053938:DNA Fragmentation; D053222:Fas Ligand Protein; D006801:Humans; D015603:Keratinocytes / Q000166:cytology*; D008562:Membrane Glycoproteins / Q000494:pharmacology*; D009856:Oncogene Proteins, Viral / Q000502:physiology*; D053221:TNF-Related Apoptosis-Inducing Ligand; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D000086082:Viroporin Proteins
D051017:Apoptosis Regulatory Proteins; D053148:Caspase 3; D020169:Caspases; D053222:Fas Ligand Protein; D008562:Membrane Glycoproteins; D009856:Oncogene Proteins, Viral; D053221:TNF-Related Apoptosis-Inducing Ligand; D014409:Tumor Necrosis Factor-alpha; C505661:FASLG protein, human; C505653:TNFSF10 protein, human; C054859:oncogene protein E5, Human papillomavirus type 16; D000086082:Viroporin Proteins; C505407:CASP3 protein, human