Mannan-binding lectin(MBL)plays a key role in the lectin pathway of complement activation and can influence cytokine expression.Toll-like receptor 4(TLR4)is expressed extensively and has been demonstrated to be involv...Mannan-binding lectin(MBL)plays a key role in the lectin pathway of complement activation and can influence cytokine expression.Toll-like receptor 4(TLR4)is expressed extensively and has been demonstrated to be involved in lipopolysaccharide(LPS)-induced signaling.We first sought to determine whether MBL exposure could modulate LPS-induced inflammatory cytokine secretion and nuclear factor-kB(NF-kB)activity by using the monocytoid cell line THP-1.We then investigated the possible mechanisms underlying any observed regulatory effect.Using ELISA and reverse transcriptase polymerase chain reaction(RT-PCR)analysis,we found that at both the protein andmRNAlevels,treatment withMBLsuppresses LPS-induced tumor-necrosis factor(TNF)-a and IL-12 production in THP-1 cells.An electrophoretic mobility shift assay and western blot analysis revealed that MBL treatment can inhibit LPS-induced NF-kB DNA binding and translocation in THP-1 cells.While the binding of MBL to THP-1 cells was evident at physiological calcium concentrations,this binding occurred optimally in response to supraphysiological calcium concentrations.This binding can be partly inhibited by treatment with either a soluble form of recombinant TLR4 extracellular domain or anti-TLR4 monoclonal antibody(HTA125).Activation of THP-1 cells by LPS treatment resulted in increased MBL binding.We also observed that MBL could directly bind to the extracellular domain of TLR4 in a dose-dependent manner,and this interaction could attenuate the binding of LPS to cell surfaces.Taken together,these data suggest that MBL may affect cytokine expression through modulation of LPS-/TLR-signaling pathways.These findings suggest that MBL may play an important role in both immune regulation and the signaling pathways involved in cytokine networks.展开更多
The Receptor-Like Kinase （RLK） is a vast protein family with over 600 genes in Arabidopsis and 1100 in rice. The Lectin RLK （LecRLK） family is believed to play crucial roles in saccharide signaling as well as stre...The Receptor-Like Kinase （RLK） is a vast protein family with over 600 genes in Arabidopsis and 1100 in rice. The Lectin RLK （LecRLK） family is believed to play crucial roles in saccharide signaling as well as stress perception. All the LecRLKs possess three domains： an N-terminal lectin domain, an intermediate transmembrane domain, and a C-terminal kinase domain. On the basis of lectin domain variability, LecRLKs have been subgrouped into three subclasses： L-, G-, and C-type LecRLKs. While the previous studies on LecRLKs were dedicated to classification, comparative structural analysis and expression analysis by promoter-based studies, most of the recent studies on LecRLKs have laid special emphasis on the potential of this gene family in regulating biotic/abiotic stress and developmental pathways in plants, thus mak- ing the prospects of studying the LecRLK-mediated regulatory mechanism exceptionally promising. In this review, we have described in detail the LecRLK gene family with respect to a historical, evolutionary, and structural point of view. Furthermore, we have laid emphasis on the LecRLKs roles in development, stress conditions, and hormonal response. We have also discussed the exciting research prospects offered by the current knowledge on the LecRLK gene family. The multitude of the LecRLK gene family members and their functional diversity mark these genes as both interesting and worthy candidates for further analysis, especially in the field of crop improvement.展开更多
基金This work was supported by the Natural Science Foundation of China(30972679).
文摘Mannan-binding lectin(MBL)plays a key role in the lectin pathway of complement activation and can influence cytokine expression.Toll-like receptor 4(TLR4)is expressed extensively and has been demonstrated to be involved in lipopolysaccharide(LPS)-induced signaling.We first sought to determine whether MBL exposure could modulate LPS-induced inflammatory cytokine secretion and nuclear factor-kB(NF-kB)activity by using the monocytoid cell line THP-1.We then investigated the possible mechanisms underlying any observed regulatory effect.Using ELISA and reverse transcriptase polymerase chain reaction(RT-PCR)analysis,we found that at both the protein andmRNAlevels,treatment withMBLsuppresses LPS-induced tumor-necrosis factor(TNF)-a and IL-12 production in THP-1 cells.An electrophoretic mobility shift assay and western blot analysis revealed that MBL treatment can inhibit LPS-induced NF-kB DNA binding and translocation in THP-1 cells.While the binding of MBL to THP-1 cells was evident at physiological calcium concentrations,this binding occurred optimally in response to supraphysiological calcium concentrations.This binding can be partly inhibited by treatment with either a soluble form of recombinant TLR4 extracellular domain or anti-TLR4 monoclonal antibody(HTA125).Activation of THP-1 cells by LPS treatment resulted in increased MBL binding.We also observed that MBL could directly bind to the extracellular domain of TLR4 in a dose-dependent manner,and this interaction could attenuate the binding of LPS to cell surfaces.Taken together,these data suggest that MBL may affect cytokine expression through modulation of LPS-/TLR-signaling pathways.These findings suggest that MBL may play an important role in both immune regulation and the signaling pathways involved in cytokine networks.
文摘The Receptor-Like Kinase （RLK） is a vast protein family with over 600 genes in Arabidopsis and 1100 in rice. The Lectin RLK （LecRLK） family is believed to play crucial roles in saccharide signaling as well as stress perception. All the LecRLKs possess three domains： an N-terminal lectin domain, an intermediate transmembrane domain, and a C-terminal kinase domain. On the basis of lectin domain variability, LecRLKs have been subgrouped into three subclasses： L-, G-, and C-type LecRLKs. While the previous studies on LecRLKs were dedicated to classification, comparative structural analysis and expression analysis by promoter-based studies, most of the recent studies on LecRLKs have laid special emphasis on the potential of this gene family in regulating biotic/abiotic stress and developmental pathways in plants, thus mak- ing the prospects of studying the LecRLK-mediated regulatory mechanism exceptionally promising. In this review, we have described in detail the LecRLK gene family with respect to a historical, evolutionary, and structural point of view. Furthermore, we have laid emphasis on the LecRLKs roles in development, stress conditions, and hormonal response. We have also discussed the exciting research prospects offered by the current knowledge on the LecRLK gene family. The multitude of the LecRLK gene family members and their functional diversity mark these genes as both interesting and worthy candidates for further analysis, especially in the field of crop improvement.
