ABSTRACT
Calenduloside E (CE), a natural triterpenoid compound isolated from Aralia elata, can protect against ox-LDL-induced human umbilical vein endothelial cell (HUVEC) injury in our previous reports. However, the exact targets and mechanisms of CE remain elusive. For the sake of resolving this question, we designed and synthesized a clickable activity-based probe (CE-P), which could be utilized to fish the functional targets in HUVECs using a gel-based strategy. Based on the previous studies of the structure-activity relationship (SAR), we introduced an alkyne moiety at the C-28 carboxylic group of CE, which kept the protective and anti-apoptosis activity. Via proteomic approach, one of the potential proteins bound to CE-P was identified as Hsp90AB1, and further verification was performed by pure recombinant Hsp90AB1 and competitive assay. These results demonstrated that CE could bind to Hsp90AB1. We also found that CE could reverse the Hsp90AB1 decrease after ox-LDL treatment. To make our results more convincing, we performed SPR analysis and the affinity kinetic assay showed that CE/CE-P could bind to Hsp90AB1 in a dose-dependent manner. Taken together, our research showed CE could probably bind to Hsp90AB1 to protect the cell injury, which might provide the basis for the further exploration of its cardiovascular protective mechanisms. For the sake of resolving this question, we designed and synthesized a clickable activity-based probe (CE-P), which could be utilized to fish the functional targets in HUVECs using a gel-based strategy.
ABSTRACT
Thermal dissipation probe (TDP) was used to continuously measure the sap flux density (Fd) of Pinus tabuliformis and Hippophae rhamnoides individuals in hilly Loess Plateau, from June to October 2015, and the environmental factors, i.e., photosynthetic active radiation (PAR), water vapor pressure deficit (VPD), and soil water content (SWC), were simultaneously monitored to clarify the difference of rainfall utilization between the two tree species in a mixed plantation. Using the methods of a Threshold-delay model, stepwise multiple regression analyses, and partial correlation analyses, this paper studied the process of Fd in these two species in response to the rainfall pulses and then determined the effects of environmental factors on Fd. The results showed that, with the increase of rainfall, the response percentages of Fd in both P. tabuliformis and H. rhamnoides increased at first but then decreased; specifically, in the range of 0-1 mm rainfall, the Fd of P. tabuliformis (-16.3%) and H. rhamnoides (-6.3%) clearly decreased; in the range of 1-5 mm rainfall, the Fd of P. tabuliformis decreased (-0.4%), whereas that of H. rhamnoides significantly increased (9.0%). The lower rainfall thresholds (RL) of Fd for P. tabuliformis and H. rhamnoides were 6.4 and 1.9 mm, respectively, with a corresponding time-lag (τ) of 1.96 and 1.67 days. In the pre-rainfall period, the peak time of Fd of P. tabuliformis converged upon 12:00-12:30 (70%), while the Fd of H. rhamnoides peaked twice, between 10:30 and 12:00 (48%) and again between 16:00 and 16:30 (30%). In the post-rainfall period, the peak time of Fd of P. tabuliformis converged upon 11:00-13:00 (40%), while that of H. rhamnoides peaked twice, between 12:00 and 13:00 (52%) and again between 16:30 and 17:00 (24%). Among the environmental factors, the rank order of factors associated with the Fd of both P. tabuliformis and H. rhamnoides was PAR>VPD, before rainfall. However, the rank order of factors influencing the Fd of P. tabuliformis was PAR>VPD>0-20 cm SWC (SWC0-20), whereas this order was different for H. rhamnoides: SWC0-20 >PAR >VPD, after rainfall. This mixed plantation of P. tabuliformis and H. rhamnoides trees had a high stability of water utilization.
