IL-1beta-induced chemokine and Fas expression are inhibited by suppressor of cytokine signalling-3 in insulin-producing cells.
OBJECTIVE
Chemokines recruit activated immune cells to sites of inflammation and are important mediators of insulitis. Activation of the pro-apoptotic receptor Fas leads to apoptosis-mediated death of the Fas-expressing cell. The pro-inflammatory cytokines IL-1beta and IFN-gamma regulate the transcription of genes encoding the Fas receptor and several chemokines. We have previously shown that suppressor of cytokine signalling (SOCS)-3 inhibits IL-1beta- and IFN-gamma-induced nitric oxide production in a beta cell line. The aim of this study was to investigate whether SOCS-3 can influence cytokine-induced Fas and chemokine expression in beta cells.


METHODS
Using a beta cell line with inducible Socs3 expression or primary neonatal rat islet cells transduced with a Socs3-encoding adenovirus, we employed real-time RT-PCR analysis to investigate whether SOCS-3 affects cytokine-induced chemokine and Fas mRNA expression. The ability of SOCS-3 to influence the activity of cytokine-responsive Fas and Mcp-1 (also known as Ccl2) promoters was measured by reporter analysis.


RESULTS
IL-1beta induced a time-dependent increase in Mcp-1 and Mip-2 (also known as Cxcl2) mRNA expression after 6 h of stimulation in insulinoma (INS)-1 and neonatal rat islet cells. This induction was inhibited when Socs3 was expressed in the cells. In INS-1 cells, IL-1beta + IFN-gamma induced a tenfold and eightfold increase of Fas mRNA expression after 6 and 24 h, respectively. This induction was inhibited at both time-points when expression of Socs3 was induced. In promoter studies SOCS-3 significantly inhibited the cytokine-induced activity of Mcp-1 and Fas promoter constructs.


CONCLUSIONS
SOCS-3 inhibits the expression of cytokine-induced chemokine and death-receptor Fas mRNA.
Jacobsen
M L B
ML
Steno Diabetes Centre, Niels Steensens Vej 6, NSK2.02, DK-2820 Gentofte, Denmark.
Rønn
S G
SG
Bruun
C
C
Larsen
C M
CM
Eizirik
D L
DL
Mandrup-Poulsen
T
T
Billestrup
N
N
D000818:Animals; D002460:Cell Line; D018932:Chemokine CCL2 / Q000235:genetics; D018925:Chemokines / Q000235:genetics*; D007328:Insulin / Q000096:biosynthesis; D050417:Insulin-Secreting Cells / Q000187:drug effects / Q000502:physiology*; D007371:Interferon-gamma / Q000494:pharmacology; D053583:Interleukin-1beta / Q000494:pharmacology*; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D015398:Signal Transduction; D000071223:Suppressor of Cytokine Signaling 3 Protein; D050826:Suppressor of Cytokine Signaling Proteins / Q000502:physiology*; D014158:Transcription, Genetic / Q000187:drug effects
C491766:Ccl2 protein, rat; D018932:Chemokine CCL2; D018925:Chemokines; D007328:Insulin; D053583:Interleukin-1beta; D012333:RNA, Messenger; C491410:Socs3 protein, rat; D000071223:Suppressor of Cytokine Signaling 3 Protein; D050826:Suppressor of Cytokine Signaling Proteins; D007371:Interferon-gamma