Study on the mechanism of the annexin II-mediated co-assembly of t-PA and plasminogen.
In order to further investigate the effect of annexin II (Ann-II) on tissue plasminogen activator (t-PA)-dependent plasminogen (PLG) activation and its interactive mechanism, recombinant native Ann-II bound t-PA, PLG and plasmin with high affinity was examined. The flow cytometric assay showed that the ann-II expression rate was higher in the human umbilical vein endothelial cell (HUVEC) (87.65%) than in the HL-60 cells as controls (35.79%). Two irrelevant proteins, bovine serum albumin (BSA) and equine IgG (EIG) had no effect on the production of plasmin. Ann-II-mediated enhancement of t-PA-dependent PLG activation was inhibited by epsilon-aminocaproic acid or by pretreatment of Ann-II with carboxypeptidase B with the inhibitive rate being 77.8% and 77.0%, respectively. It was revealed that the effect of Ann-II on PLG activation was specific for t-PA. Urokinase didn't bind to Ann-II, demonstrating the role of receptor-related lysine residues on activation of PLG, showing that the Ann-II-PLG interaction was dependent upon carboxyl-terminal lysine residues. These findings suggest that annexin II-mediated co-assembly of t-PA and PLG may promote plasmin generation and play a key role in modulating fibrinolysis on the endothelial surface.
Zhang
Xiaohui
X
Department of Hematology, Xiehe Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022.
Zhou
Huarong
H
Shen
Guanxin
G
Liu
Zhongping
Z
Hu
Yu
Y
Wei
Wenning
W
Song
Shanjun
S
D017306:Annexin A2 / Q000494:pharmacology*; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D005342:Fibrinolysis; D006801:Humans; D010958:Plasminogen / Q000378:metabolism*; D011994:Recombinant Proteins / Q000494:pharmacology; D010959:Tissue Plasminogen Activator / Q000378:metabolism*; D014471:Umbilical Veins / Q000166:cytology
D017306:Annexin A2; D011994:Recombinant Proteins; D010958:Plasminogen; D010959:Tissue Plasminogen Activator