Objective To investigate the role of TNF receptor-associated factor 2 (TRAF-2) and TRAF6 in CD40-induced nuclear factor-κB (NF-κB) signaling pathway and whether CD40 signaling requires TRAF2. Methods Human B cell li...Objective To investigate the role of TNF receptor-associated factor 2 (TRAF-2) and TRAF6 in CD40-induced nuclear factor-κB (NF-κB) signaling pathway and whether CD40 signaling requires TRAF2. Methods Human B cell lines were transfected with plasmids expressing wild type TRAF2 or dominant negative TRAF2,TRAF2-shRNA,or TRAF6-shRNA. The activation of NF-κB was detected by Western blot,kinase assay,transfactor enzyme-linked immunosorbent assay (ELISA),and fluorescence resonance energy transfer (FRET). Analysis of the role of TRAF-2 and TRAF-6 in CD40-mediated NF-κB activity was examined following stimulation with recombinant CD154. Results TRAF2 induced activity of IκB-kinases (IKKα,IKKi/ε),phosphorylation of IκBα,as well as nuclear translocation and phosphorylation of p65/RelA. In contrast,TRAF6 strongly induced NF-κB activation and nuclear translocation of p65 as well as p50 and c-Rel. Engagement of CD154-induced nuclear translocation of p65 was inhibited by a TRAF6-shRNA,but conversely was enhanced by a TRAF2-shRNA. Examination of direct interactions between CD40 and TRAFs by FRET documented that both TRAF2 and TRAF6 directly interacted with CD40. However,the two TRAFs competed for CD40 binding. Conclusions These results indicate that TRAF2 can signal in human B cells,but it is not essential for CD40-mediated NF-κB activation. Moreover,TRAF2 can compete with TRAF6 for CD40 binding,and thereby limit the capacity of CD40 engagement to induce NF-κB activation.展开更多
Bone-marrow-derived mesenchymal stem cells and endothelial progenitor cells have some interesting biological properties that make them unique for cell therapy of degenerative and cardiovascular disorders.Although both...Bone-marrow-derived mesenchymal stem cells and endothelial progenitor cells have some interesting biological properties that make them unique for cell therapy of degenerative and cardiovascular disorders.Although both cell populations have been already studied and used for their regenerative potentials,recently their special immunoregulatory features have brought much more attention.Mesenchymal stem cells and endothelial progenitor cells have both proangiogenic functions and have been shown to suppress the immune response,particularly T cell proliferation,activation,and cytokine production.This makes them suitable choices for allogeneic stem cell transplantation.Nevertheless,these two cells do not have equal immunoregulatory activities.Many elements including their extraction sources,age/passage,expression of different markers,secretion of bioactive mediators,and some others could change the efficiency of their immunosuppressive function.However,to our knowledge,no publication has yet compared mesenchymal stem cells and endothelial progenitor cells for their immunological interaction with T cells.This review aims to specifically compare the immunoregulatory effect of these two populations including their T cell suppression,deactivation,cytokine production,and regulatory T cells induction capacities.Moreover,it evaluates the implications of the tumor necrosis factor alpha-tumor necrosis factor receptor 2 axis as an emerging immune checkpoint signaling pathway controlling most of their immunological properties.展开更多
基金Supported by Key Projects of the National Science & Technology Pillar Program in the Eleventh Five-year Plan Period (2008-BAI59B02)
文摘Objective To investigate the role of TNF receptor-associated factor 2 (TRAF-2) and TRAF6 in CD40-induced nuclear factor-κB (NF-κB) signaling pathway and whether CD40 signaling requires TRAF2. Methods Human B cell lines were transfected with plasmids expressing wild type TRAF2 or dominant negative TRAF2,TRAF2-shRNA,or TRAF6-shRNA. The activation of NF-κB was detected by Western blot,kinase assay,transfactor enzyme-linked immunosorbent assay (ELISA),and fluorescence resonance energy transfer (FRET). Analysis of the role of TRAF-2 and TRAF-6 in CD40-mediated NF-κB activity was examined following stimulation with recombinant CD154. Results TRAF2 induced activity of IκB-kinases (IKKα,IKKi/ε),phosphorylation of IκBα,as well as nuclear translocation and phosphorylation of p65/RelA. In contrast,TRAF6 strongly induced NF-κB activation and nuclear translocation of p65 as well as p50 and c-Rel. Engagement of CD154-induced nuclear translocation of p65 was inhibited by a TRAF6-shRNA,but conversely was enhanced by a TRAF2-shRNA. Examination of direct interactions between CD40 and TRAFs by FRET documented that both TRAF2 and TRAF6 directly interacted with CD40. However,the two TRAFs competed for CD40 binding. Conclusions These results indicate that TRAF2 can signal in human B cells,but it is not essential for CD40-mediated NF-κB activation. Moreover,TRAF2 can compete with TRAF6 for CD40 binding,and thereby limit the capacity of CD40 engagement to induce NF-κB activation.
文摘Bone-marrow-derived mesenchymal stem cells and endothelial progenitor cells have some interesting biological properties that make them unique for cell therapy of degenerative and cardiovascular disorders.Although both cell populations have been already studied and used for their regenerative potentials,recently their special immunoregulatory features have brought much more attention.Mesenchymal stem cells and endothelial progenitor cells have both proangiogenic functions and have been shown to suppress the immune response,particularly T cell proliferation,activation,and cytokine production.This makes them suitable choices for allogeneic stem cell transplantation.Nevertheless,these two cells do not have equal immunoregulatory activities.Many elements including their extraction sources,age/passage,expression of different markers,secretion of bioactive mediators,and some others could change the efficiency of their immunosuppressive function.However,to our knowledge,no publication has yet compared mesenchymal stem cells and endothelial progenitor cells for their immunological interaction with T cells.This review aims to specifically compare the immunoregulatory effect of these two populations including their T cell suppression,deactivation,cytokine production,and regulatory T cells induction capacities.Moreover,it evaluates the implications of the tumor necrosis factor alpha-tumor necrosis factor receptor 2 axis as an emerging immune checkpoint signaling pathway controlling most of their immunological properties.
