Objective-Alpha2-antiplasmin (␣2-AP) is the major circulating inhibitor of plasmin, which plays a determining role in the regulation of intravascular fibrinolysis. We investigated the role of ␣ 2 -AP on vascular remodeling in response to angiotensin II (Ang II). Methods and Results-␣2-AP-deficient mice were performed. Ang II and N -nitro-L-arginine methyl ester (L-NAME)-induced perivascular fibrosis was significantly decreased in ␣2-AP Ϫ/Ϫ mice compared with wild-type mice. In situ gelatinolytic activity analysis shows that perivascular gelatinolytic activity was increased in ␣2-AP Ϫ/Ϫ mice, which was responsible for decreased perivascular fibrosis in response to Ang II and L-NAME. Ang II-induced arterial wall thickening, vascular cell proliferation, apoptosis, c-Myc, and collagen ⌱ expression were significantly decreased in ␣2-AP Ϫ/Ϫ mice compared with wild-type mice. Further analysis shows that increased p53 and p21 expression were responsible for inhibition of Ang II-induced vascular remodeling in ␣2-AP Ϫ/Ϫ mice. Conclusion-The results show that ␣2-AP is a critical regulator for vascular remodeling by inhibiting p53/p21 pathway, suggesting that ␣2-AP is proposed to be a potential therapeutic target for vascular remodeling.
Staphylokinase (SAK) expresses plasminogen activator (PA) activity by forming a complex with plasmin. The interaction between the plasmin-SAK complex and plasminogen was investigated using synthesized peptides, which were constructed according to the amino acid sequence of the SAK molecule. A synthetic nonadecapeptide (SAK22-40) corresponding to Glu22-Leu40 by the SAK molecule enhanced the activation of Glu-plasminogen by the plasmin-SAK complex. Analysis of IAsys resonant mirror biosensor showed that SAK22-40 bound to Glu-plasminogen. This binding was completely inhibited by IgG against the B-chain in the plasminogen molecule. But, this binding was not inhibited by IgG against lysine-binding sites (LBS) of the A-chain in the plasminogen molecule. The substitution of Lys35 with Ala in SAK22-40 did not enhance the activation of Glu-plasminogen by the plasmin-SAK complex. When SAK22-40 was administrated in a mouse thrombosis model, earlier recanalization was observed than in mice with vehicle administration. Thus, a newly synthesized peptide, SAK22-40 enhanced Glu-plasminogen activation and induced effective thrombolysis.
Since the signal transduction mechanisms responsible for liver regeneration mediated by the plasminogen/plasmin system remain largely undetermined, we have investigated whether plasmin regulates the pro-apoptotic protein Bim(EL) in primary hepatocytes. Plasmin bound to hepatocytes in part via its lysine binding sites (LBS). Plasmin also triggered phosphorylation of ERK1/2 without cell detachment. The plasmin-induced phosphorylation of ERK1/2 was inhibited by the LBS inhibitor epsilon-aminocaproic acid (EACA), the serine protease inhibitor aprotinin, and the MEK inhibitor PD98059. DFP-inactivated plasmin failed to phosphorylate ERK1/2. Plasmin temporally decreased the starvation-induced expression of Bim(EL) and activation of caspase-3 via the ERK1/2 signaling pathway, resulting in an enhancement of cell survival. The amount of mRNA for Bim increased 1 day after the injection of CCl(4) in livers of plasminogen knockout (Plg-KO) and the wild-type (WT) mice. The increase in Bim(EL) protein persisted for at least 7 days post-injection in livers of Plg-KO mice, whereas WT mice showed an increase in Bim(EL) protein 1 day after the injection. Plg-KO and WT mice showed notable phosphorylation of ERK1/2 7 and 3 days after the injection of CCl(4), respectively. Our data suggest that the plasminogen/plasmin system could decrease Bim(EL) expression via the ERK1/2 signaling pathway during liver regeneration.
The results show that c-Myc was essential for hypoxia-induced uPA expression and activity, resulting in VSMC migration and invasion. In addition, Bcl2 enhanced the c-Myc-mediated uPA/MMP-2 pathway.
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