Purification and characterization of Protein C activator from Agkistrodon acutus Venom.

Protein C (PC) plays an important role in the balance of coagulation and anticoagulation. Thus, the detection of PC activity is diagnostically significant for patients with cardiovascular diseases. Presently, the key methods to detect PC activity are the chromogenic assay and activated partial thromboplastin time (APTT) test. PROTAC used in the chromogenic assay is isolated from Agkistrodon contortrix venom as protein C activator (PCA). However, the use of the chromogenic assay is limited because of the high price of PROTAC. In this study, PCA was successfully purified from Agkistrodon acutus venom (AAV) by ion-exchange and gel chromatography. PCA from AAV has a relative molecular mass of 24 kD, calculated from the measurement of 10% sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The components of PCA were identified by MALDI-TOF/TOF-MS and mascot searches revealed that the coverage rate between PCA and zinc metalloproteinase AaPA from AAV was 21%. The chromogenic assay and APTT test were used to measure the enzymatic activity of PCA, and the results showed that PCA from AAV could specifically activate PC. In summary, the chromogenic assay described herein is highly sensitive and easy to perform.

[Effect of Agkistrodon Acutus Venom PCA on HUVEC Activity].

OBJECTIVE: To investigate the effects of Agkistrodon acutus venom protein C activator(PCA) on ultrastructure of human umbilical vein endothelial cells(HUVEC), and the levels of tissue factor(TF), vascular von Willebrand factor (vWF) and endothelin-1 secreted by HUVEC and to clarify the anti-thrombotic mechanism of PCA. METHODS: The experiments were divided into control group(DMEM), LPS group (LPS 0.1 µg/ml), PCA group(PCA 1 µg/ml) and PCA+LPS group (1 µg/ml PCA+ 0.1 µg/ml LPS). The morphology of endoplasmic reticulum, mitochondria and the number of autophagosome in HUVEC were observed by transmission electron microscopy. The TF, vWF and ET-1 were measured in the medium of each group by ELISA; RT-PCR was used to detect mRNA expression level of vWF and ET-1 in cells; and the protein expression level of TF in cells was detected by Western blot. RESULTS: Compared with the control group, the ultrastructural changes of HUVEC in the LPS group included the cell membrane getting rough, swelling of mitochondria and endoplasmic reticulum, and autophagosome increase, however, the ultrastructure differences between PCA and control group were not significant. Compared with the ultrastructure of HUVECs in LPS group, the swelling of mitochondria and endoplasmic reticulum disappeared in the LPS+PCA group, and the number of autophagosome decreased obviously. Compared with the control group, the content of ET-1, vWF and TF in cell culture supernatant, and the protein expression level of vWF, ET-1 gene and TF protein were significantly increased in LPS group (P<0.05); the expression levels of the 3 factors in the cell culture supernatant and cells in PCA group were not significantly different from the control group (P>0.05). The expression levels of TF, vWF and ET-1 in LPS group were significantly lower than those in LPS+PCA group (P<0.05). CONCLUSION: PCA(1 µg/ml) can reduce the ultrastructural changes of HUVEC induced by LPS, and inhibit the increase of TF, vWF and ET-1 secretion from HUVEC induced by LPS.

[Effect of AAVC-I on the migration of human umbilical vein endothelial cells].

OBJECTIVE: To investigate the effect of component I from agkistrodon acutus venomon (AAVC-I) the migration of human umbilical vein endothelial cells (HUVECs), and to elucidate the possible anti-angiogenic mechanism of AAVC-I. METHODS: The effect of AAVC-I on the migration of HUVECs which was cultivated in vitro and treated with AAVC-1 at four concentrations: 0, 20, 40, 80 microg/ml, was observed by methods of scratch wound-healing and Transwell assay. The expression level of mRNA and protein of P-selectin and intercellular cell adhension molecule-I (ICAM-1) were examined by RT-PCR and Western blot assay. RESULTS: Compared with the blank group, the migration ability of HUVECs in each AAVE-I treated group was reduced in a dose-dependent manner, and the expression level of the mRNA and protein of P-selectin and ICAM-1 were decreased. CONCLUSION: AAVC-I inhibits the migration of endothelial cell, which is acted by down-regulation of the expression content of mRNA and protein of P-selectin and ICAM-1.

[Expressions of fractalkine and CD11c on common carotid artery atherosclerotic plaques from apoE(-/-) mice].

OBJECTIVE: To explore the association of fractalkine (FKN) and CD11c expressions oncommon carotid artery atherosclerotic plaques from apoE(-/-) mice with the severity of atherosclerotic lesions. METHODS: Totally 24 apoE(-/-) mice were divided into two groups and fed on a high-fat diet or a normal diet for 12 weeks. Then the blood lipids as well as the plaque area and vascular stenosis rate of the common carotid artery were measured to evaluate the severity of atherosclerotic lesions of the animals. Moreover, immunohistochemical staining was performed to examine the levels of FKN and CD11c expression. RESULTS: The plaque areas and vascular stenosis rates of the common carotid artery in the experimental group were remarkably larger than those in control group (about 4-fold and 2-fold, respectively). The level of FKN expression in the experimental group was 2 times of that in the control group (P<0.05), and the number of CD11c (+) cells in the plaques in the experimental group was about 4 times of than in the control group (P<0.05). CONCLUSION: The expressions of chemokine and FKN remarkably increase in apoE (-/-) atherosclerotic plaques, suggesting that chemokine and FKN may paly important roles in the development of atherosclerosis.

[Mitochondrial mechanisms of apoptosis of human leukemia K562 cells induced by AVVC-1].

This study was purpose to investigate apoptosis pathway of leukemia K562 cells induced by anticoagulant fraction from Agkistrodon acutus venom (AVVC-1). The mitochondrial transmembrane potential (ΔΨm) of leukemia K562 cells was detected by flow cytometry with JC-1 single staining. The expression of cytochrome C in the mitochondrial of leukemia K562 cells was analyzed by Western blot after AVVC-1 treatment. The distribution of cytochrome C in leukemia K562 cells was measured by immuno-fluorescence test. The results showed that the potential of mitochondrial membrane decreased after treatment with different concentrations of AVVC-1 (12.5, 25, 50, 100 µg/ml) for 6 h (P < 0.01). The expression level of cytochrome C protein in mitochondria obviously declined after treatment with 30 µg/ml AVVC-1 for 48 h, and the fluorescent intensity of cytochrome C in cytosol was enhanced at the same time. It is concluded that AVVC-1-induced K562 cell apoptosis is related with mitochondrial damage, and cytochrome C may be a useful agent for investigating human leukemia therapy by using AVVC-1.

[Component I from Agkistrodon acutus venom induces apoptosis of K562/A02 cells by promoting caspase 3 expression].

To investigate the effects of component I from Agkistrodon acutus venom (AAVC-I) on the biological features of chronic myeloid leukemia cells, K562/A02 leukemia cells were cultured in the presence of AAVC-I (6.25 - 100 µg/ml) and the proliferation status was assayed by CCK-8 method. Morphological changes were observed by inversed microscope after Giemsa and Hochest 33258 staining, and cell apoptosis was detected by flow cytometry. Caspase 3 activity was tested by using Chromogenic Activity Assay Kit. The results showed that AAVC-I inhibited the growth of K562/A02 cells in time- and concentration-dependant manners, and the IC(50) at 48 h was 30.988 µg/ml. Giemsa and Hochest 33258 staining showed the typical apoptotic features in K562/A02 cells after induction with AAVC-I for 48 h. Flow cytometric analysis revealed that the percentage of the apoptotic cells reached from 0.88 up to 53.66 as the treated concentration was elevated from 0 to 50 µg/ml. Compared with the control group, the expression of caspase 3 in the tested group was enhanced in a dose-dependent manner (P < 0.05). It is concluded that AAVC-I can effectively inhibit the growth and promote apoptosis of K562/A02 cells. Elevated expression of caspase-3 may be attributed to the apoptosis of K562/A02 cells.

[Apoptosis of K562 cells induced by extract of Agkistrodon Halys' venom].

The study was purposed to investigate the effect of extract of Agkistrodon Halys venom on proliferation and apoptosis of K562 cells. The inhibition of K562 cell proliferation was measured by MTT assay; The morphologic changes of K562 cells was observed by microscopy; the apoptosis of K562 cells was measured by flow cytometry; the activity of extracellular signal-regulated kinase (ERK) in K562 cells was detected by Western blot. The results showed that when K562 cells were treated with 0, 1, 10, 20 microg/ml of the extraction for 48 hours, the apoptosis rates were 2.1%, 21.3%, 49.7%, 70.1%, respectively. The proliferation of K562 cells was obviously inhibited in dose-dependent manner. Typical morphologic changes significantly appeared in the extract-treated K562 cells. The extract obviously inhibited the activity of ERK in K562 cells. It is concluded that the extract of Agkistrodon Halys' venom can inhibit the proliferation of K562 cells and induce apoptosis of K562 cells.

Endoxin-mediated myocardial ischemia reperfusion injury in rats in vitro.

Myocardial ischemia reperfusion results in an increase in intracellular sodium concentration, which secondarily increases intracellular calcium via Na(+)-Ca2+ exchange, resulting in cellular injury. Endoxin is an endogenous medium of digitalis receptor and can remarkably inhibit Na+/K(+)-ATPase activity. Although the level of plasma endoxin is significantly higher during myocardial ischemia, its practical significance is unclear. This research is to investigate whether endoxin is one of important factors involved in myocardial ischemia reperfusion injury. Ischemia reperfusion injury was induced by 30 min of global ischemia and 30 min of reperfusion in isolated rat hearts. Heart rate (HR), left ventricular developed pressure (LVDP), and its first derivative (+/-dp/dtmax) were recorded. The endoxin contents, intramitochondrial Ca2+ contents, and the Na+/K(+)-ATPase activity in myocardial tissues were measured. Myocardial damages were evaluated by electron microscopy. The endoxin and intramitochondrial Ca2+ contents in myocardial tissues were remarkably higher, myocardial membrane ATPase activity was remarkably lower, the cardiac function was significantly deteriorated, and myocardial morphological damages were severe in myocardial ischemia reperfusion group vs. control. Anti-digoxin antiserum (10, 30 mg/kg) caused a significant improvement in cardiac function (LVDP and +/-dp/dtmax), Na+/K(+)-ATPase activity, and myocardial morphology, and caused a reduction of endoxin and intramitochondrial Ca2+ contents in myocardial tissues. In the present study, the endoxin antagonist, anti-digoxin antiserum, protected the myocardium against the damages induced by ischemia reperfusion in isolated rat hearts. The results suggest that endoxin might be one of main factors mediating myocardial ischemia reperfusion injury.