Celastrol targets IRAKs to block Toll-like receptor 4-mediated nuclear factor-κB activation / 中西医结合学报

<p><b>OBJECTIVE</b>Celastrol has been established as a nuclear factor-κB (NF-κB) activation inhibitor; however, the exact mechanism behind this action is still unknown. Using text-mining technology, the authors predicted that interleukin-1 receptor-associated kinases (IRAKs) are potential celastrol targets, and hypothesized that targeting IRAKs might be one way that celastrol inhibits NF-κB. This is because IRAKs are key molecules for some crucial pathways to activate NF-κB (e.g., the interleukin-1 receptor (IL-1R)/Toll-like receptor (TLR) superfamily).</p><p><b>METHODS</b>The human hepatocellular cell line (HepG2) treated with palmitic acid (PA) was used as a model for stimulating TLR4/NF-κB activation, in order to observe the potential effects of celastrol in IRAK regulation and NF-κB inhibition. The transfection of small interfering RNA was used for down-regulating TLR4, IRAK1 and IRAK4, and the Western blot method was used to detect changes in the protein expressions.</p><p><b>RESULTS</b>The results showed that celastrol could effectively inhibit PA-caused TLR4-dependent NF-κB activation in the HepG2 cells; PA also activated IRAKs, which were inhibited by celastrol. Knocking down IRAKs abolished PA-caused NF-κB activation.</p><p><b>CONCLUSION</b>The results for the first time show that targeting IRAKs is one way in which celastrol inhibits NF-κB activation.</p>

Role of microenvironment in the process of expansion of late endothelial progenitor cell in vitro / 中国医学科学院学报

<p><b>OBJECTIVE</b>To study the role of the feeder layer cells as niche in the process of expansion of late endothelial progenitor cell in vitro.</p><p><b>METHODS</b>We cultured mononuclear cells (MNC)from human peripheral blood (PB)on the plate with the feeder layer cells which were irradiated late endothelial progenitor cells(EPC)or human umbilical vein endothelial cells (HUVEC) by EGM-2. After 21 days, the numbers of obtained late EPC colonies were counted separately, and their surface antigen of the late EPC was verified by fluorescence-activated cell sorter (FACS) analysis, and their ability of forming vessel structure with Matrigel in vitro. The differentiation of single stem cell on the feeder layer cell was traced by video-microscopy.</p><p><b>RESULTS</b>After 21 days of culture,(40.0±3.9)and(39.3±3.1)late EPC colonies that MNC of a hundred milliliter PB were cultured, respectively, on the feeder layer cells of EPC and HUVEC were much more than (2.0±1.3) colonies cultured on without the feeder layer cells (all P <0.05). These cells also expressed CD31,CD34,eNOS,FLt-1,P1H12,Sendo,VE cadherin,and CD117, as shown by FACS analysis. Furthermore, they formed vessel structure with Matrigel in vitro. The video-microscopy showed the asymmetric cell division was participated by the feeder layer cell during the expansion of single stem cell.</p><p><b>CONCLUSION</b>The massive expansion of late EPC can be achieved by the provision of the feeder layer cells, which may be involved in the stem cell asymmetric cell division.</p>