Non-apoptotic signaling pathways activated by soluble Fas ligand in serum-starved human fibroblasts. Mitogen-activated protein kinases and NF-kappaB-dependent gene expression.
Many Fas-expressing cells do not undergo cell death upon Fas stimulation. In the normal human diploid cell line GM6112, the addition of soluble Fas ligand (sFasL) leads to morphological signs of cell death in less than 1% of cells. Treatment of serum-starved GM6112 fibroblasts with sFasL resulted in a rapid and transient phosphorylation of ERK1/2 without a significant increase in JNK and p38 activities. Unless co-treated with the protein synthesis inhibitor anisomycin, sFasL did not show gene-inducing activity in cells maintained in complete medium. However, when cells were serum-starved for 4 days, treatment with sFasL alone induced interleukin-6 gene expression and, less strongly, interleukin-8 gene expression. Sensitization of the gene-inducing activity by serum starvation correlated with NF-kappaB activation by sFasL. Furthermore, we found that the expression of FADD and caspase-8 was significantly reduced in serum-starved cells, whereas the level of cFLIP remained unchanged. Transfection of GM6112 cells with the antisense caspase-8 expression construct sensitized cells toward sFasL-induced NF-kappaB-dependent reporter activation. Our results support the notion that a change in the ratio of cFLIP and caspase-8 may be responsible for turning on the Fas-activated NF-kappaB pathway, which otherwise is supplanted by the death-inducing pathway.
Ahn
J H
JH
Department of Biology, Yonsei University, 134 Shinchon-Dong, Sudaemoon-Gu, Seoul 120-749, Korea.
Park
S M
SM
Cho
H S
HS
Lee
M S
MS
Yoon
J B
JB
Vilcek
J
J
Lee
T H
TH
D000818:Animals; D000841:Anisomycin / Q000494:pharmacology; D017209:Apoptosis; D029681:Arabidopsis Proteins; D015153:Blotting, Western; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; D016466:CHO Cells; D002352:Carrier Proteins / Q000378:metabolism; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases / Q000096:biosynthesis / Q000378:metabolism; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D006224:Cricetinae; D003459:Crystallins / Q000737:chemistry*; D016895:Culture Media, Serum-Free / Q000378:metabolism* / Q000494:pharmacology; D004171:Diploidy; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D004789:Enzyme Activation; D004792:Enzyme Precursors / Q000378:metabolism; D053222:Fas Ligand Protein; D044943:Fatty Acid Desaturases / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic; D017930:Genes, Reporter; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D015850:Interleukin-6 / Q000096:biosynthesis; D016209:Interleukin-8 / Q000096:biosynthesis; D047908:Intracellular Signaling Peptides and Proteins; D008156:Luciferases / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000378:metabolism*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism*; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D010766:Phosphorylation; D011485:Protein Binding; D011493:Protein Kinase C / Q000378:metabolism; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D015398:Signal Transduction; D013997:Time Factors; D014162:Transfection
D029681:Arabidopsis Proteins; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; C506386:CFLAR protein, human; D002352:Carrier Proteins; D003459:Crystallins; D016895:Culture Media, Serum-Free; D004792:Enzyme Precursors; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D015850:Interleukin-6; D016209:Interleukin-8; D047908:Intracellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins; D016328:NF-kappa B; D016376:Oligonucleotides, Antisense; D011500:Protein Synthesis Inhibitors; D000841:Anisomycin; D008156:Luciferases; D044943:Fatty Acid Desaturases; C084083:Fad7 protein, Arabidopsis; D005982:Glutathione Transferase; D011493:Protein Kinase C; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; C505530:CASP8 protein, human; C506433:CASP9 protein, human; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases