Suppressive effect of CORM-2 on platelet α-granule exocytosis in sepsis via SNARE/Munc18b complex formation / 中华危重病急救医学

Objective To investigate the suppressive effect of carbon monoxide-releasing molecule Ⅱ (CORM-2) on LPS induced platelet α-granule exocytosis in sepsis via soluble N-ethylmaleimide-sensitive factor attached protein receptor/mammalian uncoordinated 18b (SNARE/Munc18b) complex formation.Methods Blood was collected from healthy volunteers' cubital vein, then platelets were isolated by differential centrifugation. Platelets were randomly divided into 5 groups. The control group did not undergo any treatment, the LPS group received 10 mg/L LPS simulation, the CORM-2 group and iCORM-2 group underwent LPS simulation and immediate administration of CORM-2 (10μmol/L and 50μmol/L) or iCORM-2 (50μmol/L), respectively. Samples were incubated in a CO2-incubator at 37 ℃, 95% humidity, and 5% CO2. Platelet α-granule contents were detected by using standard enzyme linked immunosorbent assay (ELISA), including platelet factor 4 (PF4), platelet derived growth factor-BB (PDGF-BB), and matrix metalloproteinase-2 (MMP-2). The expression of P-selectin was detected by flow cytometer. Transmission electron microscope and immunofluorescence microscope was used to assess platelet α-granules distribution. Expressions of Munc18b and SNARE proteins including vesicle-associated membrane protein-8 (VAMP-8), synaptosomal-associated protein-23 (SNAP-23) and syntaxin-11 (STX-11) were detected by Western Bolt. The SNARE/Munc18b complex formation was detected by immunoprecipitation.Results Compared with the control group, levels of PF4, PDGF-BB, MMP-2 and P-selectinin LPS-induced platelets were found to markedly elevated, while CORM-2 (10μmol/L and 50μmol/L) could decrease platelet α-granule contents exocytosis: [PF4 (μg/L): 7.69±0.58, 6.03±0.71 vs. 10.13±0.82; PDGF-BB (μg/L): 112.71±1.79, 102.91±5.86 vs. 128.78±1.39; MMP-2 (ng/L): 32.94±2.73, 27.58±3.36 vs. 53.26±1.21; P-selectin: (17.14±0.57)%, (15.35±0.68)% vs. (23.78±0.62)%; allP < 0.01]. Transmission electron microscope and immunofluorescence microscope showed that the extent of platelet α-granules assembled to platelet plasma membrane was significantly decreased following CORM-2 treatment. Compared with the control group, the expressions of Munc18b and SNARE proteins and SNARE/Munc18b complex formation in LPS-stimulated platelets were significantly increased, while CORM-2 (10μmol/L and 50μmol/L) inhibited these elevations (Munc18b/GAPDH: 0.80±0.08, 0.69±0.01 vs. 0.99±0.09; VAMP-8/GAPDH: 0.72±0.09, 0.50±0.12 vs. 1.18±0.14; SNAP-23/GAPDH: 1.18±0.22, 0.63±0.10 vs. 1.90±0.08; STX-11/GAPDH: 0.76±0.02, 0.57±0.08 vs. 1.16±0.23; VAMP-8/ Munc18b: 0.65±0.09, 0.53±0.07 vs. 1.21±0.20; SNAP-23/Munc18b: 0.85±0.07, 0.55±0.09 vs. 1.26±0.08; STX-11/ Munc18b: 0.78±0.05, 0.61±0.10 vs. 1.39±0.16; allP < 0.01). Above all, the data showed a dose dependent change.Conclusion We could suggest that CORM-2 suppressed α-granule exocytosis in LPS-stimulated platelets and the potential mechanisms might involve SNARE/Munc18b complex formation.

Suppressive effect of exogenous carbon monoxide on abnormal platelet exocytosis and its molecular mechanism in sepsis / 中华危重病急救医学

Objective To investigate the suppressive effect of exogenous carbon monoxide (CO) on abnormal platelet exocytosis and its possible molecular mechanism. Methods Venous blood was collected from healthy volunteers. Platelet-rich plasma (PRP) was isolated from the blood by differential centrifugation. The PRP was randomly divided into five groups by random number table, namely normal control group, lipopolysaccharide (LPS) group (challenged with 10 mg/L LPS), inactively exogenous carbon monoxide releasing molecule 2 (iCORM-2) group (given 10 mg/L LPS + 50 μmol/L iCORM-2 for intervention), exogenous carbon monoxide releasing molecule 2 (CORM-2) 10 μmol/L and 50 μmol/L groups (given 10 mg/L LPS + CORM-2 10 μmol/L or 50 μmol/L for intervention). After 30 minutes, enzyme linked immunosorbent assay (ELISA) was used to determine the platelet-derived growth factor BB (PDGF-BB) and matrix metalloproteinase 2 (MMP-2). Chemical fluorescein method was used to determine the platelet adenosine triphosphate (ATP). Flow cytometer was used to determine the expression of P-selectin. The expressions of Toll-like receptor 4 (TLR4), phosphorylation of protein kinase Cθ (PKCθ) and syntaxin binding protein 1 (STXBP-1) were determined by Western Bolt. The soluble N-ethylmaleimide-sensitive factor-attachment protein receptors (SNAREs) complex formation [syntaxin 2-synaptosomal-associated protein 23-vesicle associated membrane protein 8 (STX2-SNAP23-VAMP8)] mediated by STXBP-1 was determined by immunoprecipitation. Results ① Compared with normal control group, the platelet release of PDGF-BB, MMP-2 and ATP was significantly increased after LPS challenge, and the P-selectin expression of platelet was also obviously up-regulated [PDGF-BB (μg/L): 127.53±1.78 vs. 94.35±5.84, MMP-2 (ng/L): 51.87±9.20 vs. 35.83±3.17, ATP (μmol/L): 1.288±0.056 vs. 0.975±0.010, P-selectin: (3.93±0.19)% vs. (0.44±0.10)%, all P < 0.05]. The increases in platelet release of PDGF-BB, MMP-2 and ATP were suppressed by 10 μmol/L or 50 μmol/L CORM-2 administration, as well as high-expression of P-selectin in a dose-dependent manner [PDGF-BB (μg/L): 114.68±1.35, 97.08±6.14 vs. 127.53±1.78, MMP-2 (ng/L): 32.67±8.00, 24.63±1.63 vs. 51.87±9.20, ATP (μmol/L): 0.999±0.015, 0.965±0.008 vs. 1.288±0.056, P-selectin: (1.95±0.27)%, (0.94±0.11)% vs. (3.93±0.19)%, all P < 0.05]. ② Compared with normal control group, LPS challenge resulted in a significant increase in the expression of TLR4 and the phosphorylation of PKCθ and STXBP-1 [TLR4 (gray value): 1.21±0.38 vs. 0.67±0.06, p-PKCθ (gray value): 1.36±0.20 vs. 0.44±0.03, p-STXBP-1 (gray value): 1.13±0.06 vs. 0.59±0.04, all P < 0.05]. The increases in above parameters were suppressed by 10 μmol/L or 50 μmol/L CORM-2 administration in a dose-dependent manner [TLR4 (gray value): 0.76±0.05, 0.65±0.04 vs. 1.21±0.38; p-PKCθ (gray value): 0.71±0.07, 0.47±0.10 vs. 1.36±0.20; p-STXBP-1 (gray value): 0.56±0.02, 0.48±0.01 vs. 1.13±0.06, all P < 0.05]. ③ Compared with normal control group, the SNAREs proteins in platelet that combined with STXBP-1, including STX2, SNAP23 and VAMP8, were obviously increased after LPS challenge [STX2 (gray value): 1.35±0.06 vs. 0.57±0.04, SNAP23 (gray value): 0.97±0.04 vs. 0.30±0.12, VAMP8 (gray value): 1.37±0.12 vs. 0.77±0.10, all P < 0.05]. The increases in SNAREs complex formation were suppressed by 10 μmol/L or 50 μmol/L CORM-2 administration in a dose-dependent manner [STX2 (gray value): 0.77±0.02, 0.39±0.03 vs. 1.35±0.06, SNAP23 (gray value): 0.41±0.03, 0.22±0.08 vs. 0.97±0.04, VAMP8 (gray value): 0.85±0.07, 0.66±0.07 vs. 1.37±0.12, all P < 0.05]. There was no significant difference in the above mentioned parameters between iCORM-2 group and LPS group. Conclusions LPS-induced abnormal secretion of platelet was suppressed by CORM-2 administration. The mechanism may involve the TLR4/PKCθ/STXBP-1 signaling pathway activation and the SNAREs complex formation.

Effects of electroacupuncture on learning and memory in experimental Alzeheimer′s disease / 中华物理医学与康复杂志

Objective To observe the effects of electroacupuncture ( EA) on learning and memory ability and the expression of N-ethylmaleimide-sensitive fusion factor ( NSF) in experimental Alzheimer′s disease ( AD) and to explore the mechanism involved. Methods Sixty healthy, male Sprague-Dawley rats were randomly divided into a normal group, a sham operation group, a model group and an EA group, each of 15.The model group and the EA group were injected with Aβ25-35 bilaterally in the CA1 area of the hippocampus, while the sham operation group was injected with the same amount of normal saline in the same regions. From the 1stday after the AD model had been es-tablished successfully, EA was applied to the Shen Shu ( BL23) and Bai Hui ( GV20) acupoints in the EA group once a day,6 days a week for 2 weeks. No EA was given to the other 3 groups. After the treatment, Morris water maze tests were conducted to determine assess the rats′ learning and memory ability, and immunohistochemical methods were used to test the expression level of NSF in the CA1 areas of the rats′hippocampus. Results The average es-cape latent period of the EA group was significantly shorter than that of the model group and their average platform crossing time was significantly longer. The average expression of NSF in the EA group measured as integrated optical intensity was significantly higher than that in the model group. Conclusion EA can effectively improve learning and memory ability in AD, at least in rats. The mechanism may involve increasing the expression of NSF in the CA1 area of the hippocampus.

Binding chemistry and molecular heterogeneity of neurotensin binding protein(s)/receptor in adult chicken tissues.

The study focuses on the importance of Tyr11 amino acid (AA) and subsequent stereochemistry involved in the binding process of neurotensin (NT) with its receptor (NTR)/binding protein(s) as well as the size heterogeneity. Using the binding of 125I-NT with several chicken tissues, it is identified that one of the crucial factors behind all high affinity (Kd ~10 pM) interactions is due to phenolic-OH (Φ-OH) at the para (p) position of Tyr11 within RRPYIL-CO2H (NT8-13) sequence. Replacing the p-OH only in Tyr11 by substituting with p-Cl, p-F and p-NH2 results in significant change of the binding affinity (Kd); p-OH ≈ p-NH2 (~10 pM), p-Cl (~100 pM), p-F (~120 pM). Interestingly, p-NH2 equals to p-OH displaying the highest affinity. Experiments conducted by binding several of the 125I-azido–NT analogs having azido group attached at different positions within the NT molecule have further confirmed the necessity of RRPYIL sequence for high affinity ligand-receptor interaction. The role of Tryp11 in place of Tyr11 in addition to the results above establishes a significant possibility of H–bonding occurring between p-OH of NT and NTR inside the docking space. Photo labeling of the liver tissue by substituted 125I-Y3-azido-NT analogs shows several specifically labeled bands with considerable range of molecular weight (Mr ~90-30 kDa) variations. These results indicate the existence of molecular heterogeneity concerning the sizes of NTR or else any NT binding proteins in the avian tissues. Further, the study has revealed that besides liver, several other chicken tissues also express similar specific high affinity binding (Kd ~20 pM) with varying capacities (Bmax). The order for Bmax is: liver (1.2 pMol/mg) gall bladder (1.03 pMol/mg) > spleen (0.43 pMol/mg) > brain (0.3 pMol/mg) > colon lung (0.15 pMol/mg). In all cases, the binding was reduced by GTPgS (ED50 ~ 0.05 nM), NEM (ED50 ~ 0.50 mM) and NaCl (ED50 ~30 mM), indicating the existence of NTR identical to the mammalian type-1.

Arachidonic Acid Activates K+-Cl--cotransport in HepG2 Human Hepatoblastoma Cells

K+-Cl--cotransport (KCC) has been reported to have various cellular functions, including proliferation and apoptosis of human cancer cells. However, the signal transduction pathways that control the activity of KCC are currently not well understood. In this study we investigated the possible role of phospholipase A2 (PLA2)-arachidonic acid (AA) signal in the regulatory mechanism of KCC activity. Exogenous application of AA significantly induced K+ efflux in a dose-dependent manner, which was completely blocked by R-(+)-[2-n-butyl-6,7-dichloro-2-cyclopentyl-2,3-dihydro-1-oxo-1H-inden-5-yl]oxy]acetic acid (DIOA), a specific KCC inhibitor. N-Ethylmaleimide (NEM), a KCC activator-induced K+ efflux was significantly suppressed by bromoenol lactone (BEL), an inhibitor of the calcium-independent PLA2 (iPLA2), whereas it was not significantly altered by arachidonyl trifluoromethylketone (AACOCF3) and p-bromophenacyl bromide (BPB), inhibitors of the calcium-dependent cytosolic PLA2 (cPLA2) and the secretory PLA2 (sPLA2), respectively. NEM increased AA liberation in a dose- and time-dependent manner, which was markedly prevented only by BEL. In addition, the NEM-induced ROS generation was significantly reduced by DPI and BEL, whereas AACOCF3 and BPB did not have an influence. The NEM-induced KCC activation and ROS production was not significantly affected by treatment with indomethacin (Indo) and nordihydroguaiaretic acid (NDGA), selective inhibitors of cyclooxygenase (COX) and lipoxygenase (LOX), respectively. Treatment with 5,8,11,14-eicosatetraynoic acid (ETYA), a non-metabolizable analogue of AA, markedly produced ROS and activated the KCC. Collectively, these results suggest that iPLA2-AA signal may be essentially involved in the mechanism of ROS-mediated KCC activation in HepG2 cells.

Regulating Proteins Participating in Neurotransmitter Release of Synaptic Vesicles at Nerve Terminals / 上海第二医科大学学报

Neurotransmitter release is controlled by groups of proteins associated with the membranes of synaptic vesicles and the presynaptic membranes.It is a highly dynamic process which is spatially and temporally regulated via a cascade of protein-protein interactions.These proteins participate in each step of the synaptic vesicle circulation at nerve terminals including the formation of soluble N-ethylmaleimide-sensitive factor-attachment protein receptors complex,the targeted trafficking of synaptic vesicles,the vesicle docking,the neurotransmitter release and finally the reuse of the proteins.This article focuses on the physiological function and the interactions of these regulating proteins.

THE EFFECT OF CORIARIA LECTON-ACTIVITED ASTROCYTE-CONDITIONED MEDIUM AND CNQX ON NSF OF THE CEREBRAL OF NORMAL RATS AND CULTURED NEURONS / 解剖学报

Objective To explore the effects of astrocytes on the N-ethylmaleimide-sensitive fusion protin,(NSF) and AMPA receptor of the neurons as well as their function in epileptogenesis. Methods ACM was injected into lateral ventricle of SD rats and the behaviour changes were observed; Immunohistochemical method was used to assess the changes of the expression of NSF in the cerebral cortex and hippocampus; The cultured neurons were divided into control group, ACM group and CNQX+ACM group at random, immunocytochemistry was used to assess the changes of the expression of NSF, Western blotting was used to assess the changes of the content of NSF of the cultured neurons. Results Seizure was observed in ACM group 30 min after injecting ACM. the immunoreaction of NSF in hippocampus and cerebral cortex of rats were depressed than those of the control group 2h, 4h after injecting ACM (P

Platelet activating factor-induced aggregation of calf platelets: apparent positive cooperativity in the kinetics and non competitive inhibition by diltiazem.

Aggregation of calf platelets by platelet activating factor was characterized by a spectrophotometric method. The aggregation kinetics of both platelet-rich plasma and purified platelets showed concave up double-reciprocal plots and linear Hill plots with h > 1 (1·7 ± 02) consistent with positive cooperativity. Comparable values of maximum rates of aggregation (R) were obtained with platelet-rich plasma (0·25 ± 0·08) and purified platelets (0·28 ± 0.18) but the half-maximal saturation concentration (S0.5) differed greatly between platelet-rich plasma (6 ± 3 nM) and purified platelets (0·28 ± 0·18 nM). An Arrhenius activation energy of 21 ± 2 kcal/mol was found for aggregation of purified platelets. Diltiazem was inhibitory with half-maximal inhibitory concentration (I0·5) of 4 M but the inhibition was not competitive. Diltiazem inhibited rates but not the extent of shape-change. The receptor-antagonist and sulphydryl reagent N-ethylmaleimide and the platelet antagonistic omega-3-fatty acid, 5,8,11,14,17-eicosa pentaenoic acid, inhibited both rates and extent of shape-change reactions and inhibited aggregation competitively (I0.5 ~ 5 μM). Eicosa pentaenoic acid at > 25 μM could abolish shape-change reactions and at 50 μM served as an activator of platelets and the activation was enhanced by aspirin (1 mM). Although N-ethylmaleimide at > 20 μM could also induce platelet activation it failed to induce aggregation and aspirin had no effect on the shape-change reactions induced by it.

Resolution of DNA polymerase-α-primase complex and primase free DNA polymerase α from embryonic chicken brain.

DNA polymerase-α from embryonic chicken brain was resolved on DEAEcellulose into 3 component activities that remained distinct upon rechromatography. Product formation by each activity required exogenously added template-primer DNA, all 4 deoxynucleoside triphosphates, and a divalent metal cation. Each form incorporated [3H]- dTTP or [3H]-dCTP into a high molecular weight product that was identified as DNA by its chromatographic behavior and its sensitivity to DNase. High ionic strength, Nethylmaleimide, and the polymerase-α-specific inhibitor aphidicolin inhibited each activity; the apparent Ki, value of aphidicolin was 3·0 μΜ in each case. Based on these results, the 3 activities were identified as multiple forms of DNA polymerase-α . Experiments using embryonic chicken brains of various ages indicated that polymerase-α1, and polymerase-α3 reached maximal activity in 9-day-old embryos, while polymerase-α2 activity was elevated at a slightly later developmental stage. Using poly (dC) as template, high primase activity was detected in polymerase-α1, fractions.