Jacquet Sebastien, Nishino Yasuhiro, Kumphune Sarawut, Sicard Pierre, Clark James E, Kobayashi Koichi S, Flavell Richard A, Eickhoff Jan, Cotten Matt, Marber Michael S
Cardiovascular Division, King's College London, The Rayne Institute, St. Thomas' Hospital, London SE1 7EH, United Kingdom.
J Biol Chem. 2008 May 2;283(18):11964-71. doi: 10.1074/jbc.M707750200. Epub 2008 Feb 29.
The activation of p38 MAPK by dual phosphorylation aggravates myocardial ischemic injury and depresses cardiac contractile function. SB203580, an ATP-competitive inhibitor of p38 MAPK and other kinases, prevents this dual phosphorylation during ischemia. Studies in non-cardiac tissue have shown receptor-interacting protein 2 (RIP2) lies upstream of p38 MAPK, is SB203580-sensitive and ischemia-responsive, and aggravates ischemic injury. We therefore examined the RIP2-p38 MAPK signaling axis in the heart. Adenovirus-driven expression of wild-type RIP2 in adult rat ventricular myocytes caused robust, SB203580-sensitive dual phosphorylation of p38 MAPK associated with activation of p38 MAPK kinases MKK3, MKK4, and MKK6. The effect of SB203580 was recapitulated by unrelated inhibitors of RIP2 or the downstream MAPK kinase kinase, TAK1. However, overexpression of wild-type, kinase-dead, caspase recruitment domain-deleted, or kinase-dead and caspase recruitment domain-deleted forms of RIP2 had no effect on the activating dual phosphorylation of p38 MAPK during simulated ischemia. Similarly, p38 MAPK activation and myocardial infarction size in response to true ischemia did not differ between hearts from wild-type and RIP2 null mice. However, both p38 MAPK activation and the contractile depression caused by the endotoxin component muramyl dipeptide were attenuated by SB203580 and in RIP2 null hearts. Although RIP2 can cause myocardial p38 MAPK dual phosphorylation in the heart under some circumstances, it is not responsible for the SB203580-sensitive pattern of activation during ischemia.
双重磷酸化激活p38丝裂原活化蛋白激酶（p38 MAPK）会加重心肌缺血损伤并抑制心脏收缩功能。SB203580是一种p38 MAPK及其他激酶的ATP竞争性抑制剂，可在缺血期间阻止这种双重磷酸化。非心脏组织研究表明，受体相互作用蛋白2（RIP2）位于p38 MAPK上游，对SB203580敏感且对缺血有反应，并会加重缺血损伤。因此，我们研究了心脏中的RIP2-p38 MAPK信号轴。腺病毒驱动的野生型RIP2在成年大鼠心室肌细胞中的表达导致p38 MAPK发生强烈的、对SB203580敏感的双重磷酸化，这与p38 MAPK激酶MKK3、MKK4和MKK6的激活相关。RIP2或下游丝裂原活化蛋白激酶激酶激酶TAK1的无关抑制剂也能重现SB203580的作用效果。然而，野生型、激酶失活型、半胱天冬酶募集结构域缺失型或激酶失活且半胱天冬酶募集结构域缺失型RIP2的过表达对模拟缺血期间p38 MAPK的激活双重磷酸化没有影响。同样，野生型和RIP2基因敲除小鼠心脏在真正缺血时，p38 MAPK激活和心肌梗死面积并无差异。然而，内毒素成分胞壁酰二肽引起的p38 MAPK激活和收缩抑制在SB203580处理的心脏以及RIP2基因敲除心脏中均减弱。尽管在某些情况下RIP2可导致心脏中p38 MAPK双重磷酸化，但它并非缺血期间对SB203580敏感的激活模式的原因。
