Interleukin-4 inhibits caspase-3 by regulating several proteins in the Fas pathway during initial stages of human T helper 2 cell differentiation.
Interleukin-4 (IL-4) is the main cytokine that polarizes activated naïve CD4+ T cells in the T helper 2 (Th2) direction. IL-4 also regulates the subsequent stages of Th2 cell-mediated diseases, such as allergies. We conducted a proteomics study to identify IL-4-induced differences during the initial stages of T helper cell differentiation. Primary CD4+ T lymphocytes were isolated from human cord blood, activated through CD3 and CD28, and cultured in the presence or absence of IL-4. Soluble proteins were separated by two-dimensional electrophoresis and visualized by staining with autoradiography, which indicated that at least 20 proteins might be regulated by IL-4. From this minimum of 20 stained proteins, altogether 35 proteins were identified using tandem mass spectrometry. Interestingly the fragmented form of GDP dissociation inhibitor expressed in lymphocytes/Rho GDP dissociation inhibitor 2 (Ly-GDI), a known target of Caspase-3, was observed to be down-regulated in IL-4-treated cells. It was shown in further studies that IL-4 decreases Caspase-3 activity and cell death in these cells. Neutralizing Fas-Fas ligand interaction led to decreased Caspase-3 activity and lowered Ly-GDI fragmentation. We further characterized the effects of IL-4 on the expression of main regulators in the Fas-mediated pathway. We demonstrated that IL-4 decreases expression of Fas receptor and increases expression of Bid, Bcl-2, and Bcl-xL. Importantly IL-4 significantly up-regulated the short form of c-FLIP, although the levels of c-FLIP long were unaltered after IL-4 induction. Taken together, our results indicate that IL-4 inhibits caspase activity during the initial stages of human Th2 cell differentiation by regulating expression of several key players in the Fas-induced pathway.
Rautajoki
Kirsi J
KJ
Turku Centre for Biotechnology, University of Turku and Abo Akademi, Tykistökatu 6A, 5th floor, FIN-20521 Turku, Finland. kirsi.rautajoki@btk.fi
Marttila
Elisa M
EM
Nyman
Tuula A
TA
Lahesmaa
Riitta
R
D053446:CASP8 and FADD-Like Apoptosis Regulating Protein / Q000378:metabolism; D015496:CD4-Positive T-Lymphocytes / Q000201:enzymology; D053148:Caspase 3 / Q000378:metabolism*; D016923:Cell Death; D002454:Cell Differentiation; D002478:Cells, Cultured; D053222:Fas Ligand Protein / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D051550:I-kappa B Kinase / Q000378:metabolism; D015847:Interleukin-4 / Q000494:pharmacology*; D008213:Lymphocyte Activation; D008954:Models, Biological; D020543:Proteome / Q000378:metabolism; D015398:Signal Transduction; D053719:Tandem Mass Spectrometry; D018418:Th2 Cells / Q000201:enzymology / Q000378:metabolism / Q000502:physiology*; D019014:fas Receptor / Q000378:metabolism*
D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; C506386:CFLAR protein, human; D053222:Fas Ligand Protein; D020543:Proteome; D019014:fas Receptor; D015847:Interleukin-4; D051550:I-kappa B Kinase; D053148:Caspase 3