Publications (2)8.4 Total impact
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Article: Involvement of IRAKs and TRAFs in anti-β₂GPI/β₂GPI-induced tissue factor expression in THP-1 cells.
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ABSTRACT: Our previous study has shown that Toll-like receptor 4 (TLR4) and its signalling pathway contribute to anti-β₂-glycoprotein I/β₂-glycoprotein I (anti-β₂GPI/β₂GPI)-induced tissue factor (TF) expression in human acute monocytic leukaemia cell line THP-1 and annexin A2 (ANX2) is involved in this pathway. However, its downstream molecules have not been well explored. In this study, we have established that interleukin-1 receptor-associated kinases (IRAKs) and tumour necrosis factor receptor-associated factors (TRAFs) are crucial downstream molecules of anti-β₂GPI/β₂GPI-induced TLR4 signaling pathway in THP-1 cells and explored the potential mechanisms of their self-regulation. Treatment of THP-1 cells with anti-β₂GPI/β₂GPI complex induced IRAKs and TRAFs expression and activation. Anti-β₂GPI/β₂GPI complex firstly induced expression of IRAK4 and IRAK1, then IRAK1 phosphorylation and last IRAK3 upregulation. In addition, anti-β₂GPI/β₂GPI complex simultaneously and acutely enhanced mRNA levels of TRAF6, TRAF4 and zinc finger protein A20 (A20), while chronically increased A20 protein level. Moreover, anti-β₂GPI/β₂GPI complex-induced IRAKs and TRAFs expression and activation were attenuated by knockdown of ANX2 by infection with ANX2-specific RNA interference lentiviruses (LV-RNAi-ANX2) or by treatment with paclitaxel, which inhibits TLR4 as an antagonist of myeloid differentiation protein 2 (MD-2) ligand. Furthermore, both IRAK1/4 inhibitor and a specific proteasome inhibitor MG-132 could attenuate TRAFs expression as well as TF expression induced by anti-β₂GPI/β₂GPI complex. In conclusion, our results indicate that IRAKs and TRAFs play important roles in anti-β₂GPI/β₂GPI-stimulated TLR4/TF signaling pathway in THP-1 cells and contribute to the pathological processes of antiphospholipid syndrome (APS).Thrombosis and Haemostasis 09/2011; 106(6):1158-69. · 5.04 Impact Factor -
Article: Toll-like receptor (TLR)-4 mediates anti-β2GPI/β2GPI-induced tissue factor expression in THP-1 cells.
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ABSTRACT: Our previous study demonstrated that annexin A2 (ANX2) on cell surface could function as a mediator and stimulate tissue factor (TF) expression of monocytes by anti-β₂-glycoprotein I/β₂-glycoprotein I complex (anti-β₂GPI/β₂GPI). However, ANX2 is not a transmembrane protein and lacks the intracellular signal transduction pathway. Growing evidence suggests that Toll-like receptor 4 (TLR-4) might act as an 'adaptor' for intracellular signal transduction in anti-β₂GPI/β₂GPI-induced TF expressing cells. In the current study, we investigated the roles of TLR-4 and its related molecules, myeloid differentiation protein 2 (MD-2) and myeloid differentiation factor 88 (MyD88), in anti-β₂GPI/β₂GPI-induced TF expressing human monocytic-derived THP-1 (human acute monocytic leukaemia) cells. The relationship of TLR-4 and ANX2 in this process was also explored. Along with TF, expression of TLR-4, MD-2 and MyD88 in THP-1 cells increased significantly when treated by anti-β₂GPI (10 µg/ml)/β₂GPI (100 µg/ml) complex. The addition of paclitaxel, which competes with the MD-2 ligand, could inhibit the effects of anti-β₂GPI/β₂GPI on TLR-4, MD-2, MyD88 and TF expression. Both ANX2 and TLR-4 in THP-1 cell lysates could bind to β₂GPI that had been conjugated to a column (β₂GPI-Affi-Gel). Furthermore, TLR-4, MD-2, MyD88 and TF expression was remarkably diminished in THP-1 cells infected with ANX2-specific RNA interference (RNAi) lentivirus (LV-RNAi-ANX2), in spite of treatment with a similar concentration of anti-β₂GPI/β₂GPI complex. These results indicate that TLR-4 and its signal transduction pathway contribute to anti-β₂GPI/β₂GPI-induced TF expression in THP-1 cells, and the effects of TLR-4 with ANX2 are tightly co-operative.Clinical & Experimental Immunology 02/2011; 163(2):189-98. · 3.36 Impact Factor
