Shimizu N, Yoshiyama M, Omura T, Hanatani A, Kim S, Takeuchi K, Iwao H, Yoshikawa J
First Department of Internal Medicine, Osaka City University Medical School, Japan.
Cardiovasc Res. 1998 Apr;38(1):116-24. doi: 10.1016/s0008-6363(97)00327-1.
The purpose of this study was to examine the activation of mitogen-activated protein kinases (MAPK) plus activator protein-1 (AP-1) and nuclear factor-kB (NF-kB) DNA binding activities, all of which seem to be important in a signal transduction cascade upstream of the increased level of mRNA expression observed after myocardial infarction.
Myocardial infarction was produced in Wistar rats. The activities of MAPKs in the ischemic region were measured using an in-gel kinase method or an in vitro kinase method. AP-1 and NF-kB binding was determined using an electrophoretic mobility shift assay. Levels of transforming growth factor beta-1(TGF-beta-1) and collagen I and III mRNAs were analyzed by Northern blot hybridization.
p42 Extracellular signal-regulated kinase (ERK), p44ERK and p38MAPK activities increased 5.2-fold, 4.3-fold and 1.9-fold (P < 0.01), respectively, at 5 min after coronary artery ligation but returned to normal levels by 30 min. p55c-Jun NH2-terminal kinase (JNK) and p46JNK activities increased 4.0-fold and 3.2-fold (P < 0.01), respectively, at 15 min and returned to normal levels by 24 h after ligation. AP-1 DNA and NF-kB binding activities increased 8.7-fold and 7.1-fold (P < 0.01), respectively, at 3 days but returned to normal levels by 7 days after ligation. Interestingly, analyses of the levels of TGF-beta-1, collagen I and III mRNAs revealed increases of 6.3-fold, 15.2-fold and 12.0-fold (P < 0.01), respectively, at 1 week after myocardial infarction.
Myocardial ischemia increased MAPK activities, which were followed by enhancement of AP-1 and NF-kB DNA binding activity in areas of myocardial infarction in rats. These signal transduction mechanisms may contribute to the myocardial ischemia and injury associated with myocardial infarction by causing an increased expression of TGF-beta-1 mRNA, collagen I and III in the area.
本研究旨在检测丝裂原活化蛋白激酶（MAPK）、活化蛋白-1（AP-1）以及核因子-κB（NF-κB）的DNA结合活性，这些在心肌梗死后观察到的mRNA表达水平升高的上游信号转导级联反应中似乎都很重要。
在Wistar大鼠中制造心肌梗死模型。采用凝胶内激酶法或体外激酶法测量缺血区域的MAPK活性。使用电泳迁移率变动分析确定AP-1和NF-κB的结合情况。通过Northern印迹杂交分析转化生长因子β-1（TGF-β-1）以及I型和III型胶原mRNA的水平。
冠状动脉结扎后5分钟，p42细胞外信号调节激酶（ERK）、p44ERK和p38MAPK活性分别增加了5.2倍、4.3倍和1.9倍（P<0.01），但在30分钟时恢复到正常水平。p55c-Jun氨基末端激酶（JNK）和p46JNK活性在结扎后15分钟分别增加了4.0倍和3.2倍（P<0.01），并在结扎后24小时恢复到正常水平。AP-1 DNA和NF-κB结合活性在结扎后3天分别增加了8.7倍和7.1倍（P<0.01），但在结扎后7天恢复到正常水平。有趣的是，对TGF-β-1、I型和III型胶原mRNA水平的分析显示，在心肌梗死后1周分别增加了6.3倍、15.2倍和12.0倍（P<0.01）。
心肌缺血增加了MAPK活性，随后大鼠心肌梗死区域的AP-1和NF-κB DNA结合活性增强。这些信号转导机制可能通过导致梗死区域TGF-β-1 mRNA、I型和III型胶原表达增加，从而促成与心肌梗死相关的心肌缺血和损伤。
