Tanno Masaya, Bassi Rekha, Gorog Diana A, Saurin Adrian T, Jiang Jie, Heads Richard J, Martin Jody L, Davis Roger J, Flavell Richard A, Marber Michael S
Department of Cardiology, Guy's, King's and St Thomas' School of Medicine, King's College London, The Rayne Institute, St Thomas' Hospital, London, UK.
Circ Res. 2003 Aug 8;93(3):254-61. doi: 10.1161/01.RES.0000083490.43943.85. Epub 2003 Jun 26.
The ischemic activation of p38alpha mitogen-activated protein kinase (p38alpha-MAPK) is thought to contribute to myocardial injury. Under other circumstances, activation is through dual phosphorylation by MAPK kinase 3 (MKK3). Therefore, the mkk3-/- murine heart should be protected during ischemia. In retrogradely perfused mkk3-/- and mkk3+/+ mouse hearts subjected to 30 minutes of global ischemia and 120 minutes of reperfusion, infarction/risk volume was similar (50+/-5 versus 51+/-4, P=0.93, respectively), as was intraischemic p38-MAPK phosphorylation (10 minutes ischemia as percent basal, 608+/-224 versus 384+/-104, P=0.43, respectively). This occurred despite undetectable activation of MKK3/6 in mkk3-/- hearts. However, tumor necrosis factor (TNF)-induced p38-MAPK phosphorylation was markedly diminished in mkk3-/- vs mkk3+/+ hearts (percent basal, 127+/-23 versus 540+/-267, respectively, P=0.04), suggesting an MKK-independent activation mechanism by ischemia. Hence, we examined p38-MAPK activation by TAB1-associated autophosphorylation. In wild-type mice and mkk3-/- mice, the p38-MAPK catalytic site inhibitor SB203580 (1 micromol/L) diminished phosphorylation during ischemia versus control (10 minutes ischemia as percent basal, 143+/-2 versus 436+/-96, P=0.003, and 122+/-25 versus 623+/-176, P=0.05, respectively) and reduced infarction volume (infarction/risk volume, 57+/-5 versus 36+/-3, P<0.001, and 50+/-5 versus 29+/-3, P=0.003, respectively) but did not alter TNF-induced activation, although in homogenates of ischemic hearts but not TNF-exposed hearts, p38-MAPK was associated with TAB1. Furthermore, adenovirally expressed wild-type and drug-resistant p38alpha-MAPK, lacking the SB203580 binding site, was phosphorylated when H9c2 myoblasts were subjected to simulated ischemia. However, SB203580 (1 micromol/L) did not prevent the phosphorylation of resistant p38alpha-MAPK. These findings suggest the ischemic activation of p38-MAPK contributing to myocardial injury is by TAB1-associated autophosphorylation.
p38α丝裂原活化蛋白激酶（p38α-MAPK）的缺血激活被认为与心肌损伤有关。在其他情况下，激活是通过丝裂原活化蛋白激酶激酶3（MKK3）的双重磷酸化实现的。因此，mkk3-/-小鼠心脏在缺血期间应受到保护。在逆行灌注的mkk3-/-和mkk3+/+小鼠心脏中，进行30分钟全心缺血和120分钟再灌注后，梗死面积/危险面积相似（分别为50±5和51±4，P = 0.93），缺血期间p38-MAPK磷酸化情况也相似（缺血10分钟时相对于基础水平的百分比，分别为608±224和384±104，P = 0.43）。尽管在mkk3-/-心脏中未检测到MKK3/6的激活，但仍出现了上述情况。然而，与mkk3+/+心脏相比，肿瘤坏死因子（TNF）诱导的mkk3-/-心脏中p38-MAPK磷酸化明显减少（相对于基础水平的百分比，分别为127±23和540±267，P = 0.04），这表明缺血存在一种不依赖MKK的激活机制。因此，我们研究了与TAB1相关的自磷酸化对p38-MAPK的激活作用。在野生型小鼠和mkk3-/-小鼠中，p38-MAPK催化位点抑制剂SB203580（1 μmol/L）可减少缺血期间的磷酸化，与对照组相比（缺血10分钟时相对于基础水平的百分比，分别为143±2和436±96，P = 0.003，以及122±25和623±176，P = 0.05），并减少梗死面积（梗死面积/危险面积，分别为57±5和36±3，P<0.001，以及50±5和29±3，P = 0.003），但不改变TNF诱导的激活，尽管在缺血心脏匀浆中而非TNF处理的心脏中，p38-MAPK与TAB1相关。此外，当H9c2成肌细胞遭受模拟缺血时，腺病毒表达的缺乏SB203580结合位点的野生型和耐药p38α-MAPK会发生磷酸化。然而，SB203580（1 μmol/L）并不能阻止耐药p38α-MAPK的磷酸化。这些发现表明，导致心肌损伤的p38-MAPK的缺血激活是通过与TAB1相关的自磷酸化实现的。
