TY - JOUR
T1 - Inhibition of cellular FLICE-like inhibitory protein abolishes insensitivity to interferon-α and death receptor stimulation in resistant variants of the human U937 cell line
AU - Blomberg, Jeanette
AU - Höglund, Andreas
AU - Eriksson, David
AU - Ruuth, Kristina
AU - Jacobsson, Maria
AU - Lundgren, Erik
AU - Nilsson, Jonas A
PY - 2011/8
Y1 - 2011/8
N2 - Type I interferons constitute a family of pleiotropic cytokines that have a key role in both adaptive and innate immunity. The interferon signalling pathways mediate transcriptional regulation of hundreds of genes, which result in mRNA degradation, decreased protein synthesis, cell cycle inhibition and induction of apoptosis. To elucidate regulatory networks important for interferon induced cell death, we generated interferon resistant U937 cells by selection in progressively increasing concentrations of interferon-α (IFN-α). The results show that IFN-α activates the death receptor signalling pathway and that IFN resistance was associated with cross-resistance to several death receptor ligands in a manner similar to previously described Fas resistant U937 cell lines. Increased expression of the long splice variant of the cellular FLICE-like inhibitor protein (cFLIP-L) was associated with the resistance to death receptor and IFN-α stimulation. Accordingly, inhibition of cFLIP-L expression with cycloheximide or through cFLIP short harpin RNA interference restored sensitivity to Fas and/or IFN-α. Thus, we now show that selection for interferon resistance can generate cells with increased expression of cFLIP, which protects the cells from both IFN-α and death receptor mediated apoptosis.
AB - Type I interferons constitute a family of pleiotropic cytokines that have a key role in both adaptive and innate immunity. The interferon signalling pathways mediate transcriptional regulation of hundreds of genes, which result in mRNA degradation, decreased protein synthesis, cell cycle inhibition and induction of apoptosis. To elucidate regulatory networks important for interferon induced cell death, we generated interferon resistant U937 cells by selection in progressively increasing concentrations of interferon-α (IFN-α). The results show that IFN-α activates the death receptor signalling pathway and that IFN resistance was associated with cross-resistance to several death receptor ligands in a manner similar to previously described Fas resistant U937 cell lines. Increased expression of the long splice variant of the cellular FLICE-like inhibitor protein (cFLIP-L) was associated with the resistance to death receptor and IFN-α stimulation. Accordingly, inhibition of cFLIP-L expression with cycloheximide or through cFLIP short harpin RNA interference restored sensitivity to Fas and/or IFN-α. Thus, we now show that selection for interferon resistance can generate cells with increased expression of cFLIP, which protects the cells from both IFN-α and death receptor mediated apoptosis.
KW - Antibodies/pharmacology
KW - Apoptosis/drug effects
KW - Apoptosis Regulatory Proteins/antagonists & inhibitors
KW - CASP8 and FADD-Like Apoptosis Regulating Protein/antagonists & inhibitors
KW - Caspase 8/metabolism
KW - Caspase 9/metabolism
KW - Cycloheximide/pharmacology
KW - Drug Resistance
KW - Enzyme Activation
KW - Enzyme Assays
KW - Gene Expression Regulation
KW - Humans
KW - Interferon-alpha/pharmacology
KW - Interphase
KW - RNA Interference
KW - Receptors, Death Domain/metabolism
KW - U937 Cells
KW - Up-Regulation
U2 - 10.1007/s10495-011-0606-0
DO - 10.1007/s10495-011-0606-0
M3 - Article
C2 - 21562857
SN - 1360-8185
VL - 16
SP - 783
EP - 794
JO - Apoptosis
JF - Apoptosis
IS - 8
ER -