Differential activation of p38 mitogen-activated protein kinase isoforms depending on signal strength
Differential activation of p38 mitogen-activated protein kinase isoforms depending on signal strength
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DOI：
10.1074/jbc.m007835200
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发表时间：
2000-12-22
影响因子：
4.8
通讯作者：
Nebreda, AR
中科院分区：
文献类型：
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作者：
Alonso, G;Ambrosino, C;Nebreda, AR
我们研究了丝裂原活化蛋白激酶（MAPK）激酶MKK6激活MAPK的p38亚家族的不同成员的能力，发现一些MKK6突变体可以有效地激活p38 α，但不能激活p38 γ。相比之下，组成型活性MKK 6突变体以相似的程度激活两种p38 MAPK亚型。在非洲爪蟾卵母细胞中共表达和体外使用来自转染细胞的MKK6免疫沉淀物或细菌产生的重组蛋白获得相同的结果。我们还发现MKK6对p38 α的优先激活与MKK6与p38 α的结合比与p38 γ的结合更有效相关。此外，无论是在体外还是在注射的卵母细胞中，增加浓度的组成型活性MKK6差异性地激活单独的p38 α（低MKK6活性）或p38 α和p38 γ两者（高MKK6活性）。选择性的决定因素位于p38 MAPK的羧基末端叶，但不对应于激活环或常见的对接序列。我们还发现，不同的刺激可以诱导不同水平的内源性MKK6活性，与p38 MAPK的差异活化相关。我们的研究结果表明，MKK6的活动水平所引发的一个给定的刺激可能会决定下游p38 MAPK激活的模式，在特定的反应。
We have investigated the ability of the mitogen-activated protein kinase (MAPK) kinase MKK6 to activate different members of the p38 subfamily of MAPKs and found that some MKK6 mutants can efficiently activate p38 alpha but not p38 gamma. In contrast, a constitutively active MKK6 mutant activated both p38 MAPK isoforms to similar extents. The same results were obtained upon coexpression in Xenopus oocytes and in vitro using either MKK6 immunoprecipitates from transfected cells or bacterially produced recombinant proteins. We also found that the preferential activation of p38 alpha by MKK6 correlated with more efficient binding of MKK6 to p38 alpha than to p38 gamma. Furthermore, increasing concentrations of constitutively active MKK6 differentially activated either p38 alpha alone (low MKK6 activity) or both p38 alpha and p38 gamma (high MKK6 activity), both in vitro and in injected oocytes. The determinants for selectivity are located at the carboxyl-terminal lobe of p38 MAPKs but do not correspond to the activation loop or common docking sequences. We also showed that different stimuli can induce different levels of endogenous MKK6 activity that correlate with differential activation of p38 MAPKs. Our results suggest that the level of MKK6 activity triggered by a given stimulus may determine the pattern of downstream p38 MAPK activation in the particular response.