Multiple signal transduction pathways link Na+/K+-ATPase to growth-related genes in cardiac myocytes -: The roles of Ras and mitogen-activated protein kinases
Multiple signal transduction pathways link Na+/K+-ATPase to growth-related genes in cardiac myocytes -: The roles of Ras and mitogen-activated protein kinases
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DOI：
10.1074/jbc.273.24.15249
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发表时间：
1998-06-12
影响因子：
4.8
通讯作者：
Xie, ZJ
中科院分区：
文献类型：
--
作者：
Kometiani, P;Li, J;Xie, ZJ
在此之前，我们发现在新生大鼠心肌细胞中，无毒浓度的哇巴因部分抑制Na+/K+-ATPase导致心肌肥大标志基因的肥大生长和转录调控，鉴于RAS和p42/44丝裂原激活蛋白激酶(MAPKs)作为心肌肥厚的关键介质所起的作用，本工作的目的是探讨它们在哇巴因启动的信号通路中的作用，这些信号通路调节这些心肌细胞的四个生长相关基因，即c-Fos、骨骼α-肌动蛋白、心钠素和Na+/K+-ATPase的α(3)亚单位。哇巴因引起RAS和P42/44 MAPK的快速激活；后者持续时间超过90min。利用腺病毒介导的显性负性RAS突变体的高效表达，以及MAPK的特异性抑制剂，哇巴因激活Ras-Raf-MEK-P42/44MAPK级联反应。突变体RAS、RAS法尼化抑制剂RAS和MEK抑制剂对哇巴因诱导的四个基因mRNAs变化的影响表明：(A)骨骼α-肌动蛋白的诱导依赖于大鼠；(B)α(3)抑制依赖于Ras-P42/44MAPK级联，c)c-fos或心钠素基因的诱导部分通过Ras-P42/44MAPK级联，部分通过不依赖RAS和P42/44MAPKs的途径，所有哇巴因效应都需要细胞外钙离子，并可被钙离子/钙调蛋白拮抗剂或蛋白激酶C抑制剂减弱。结果表明：(A)与肌膜Na+/K+-ATPase相关的信号通路共享涉及钙离子和蛋白激酶C的早期片段，但仅分成多个分支，其中只有一部分涉及PAS或P42/44 MAPK，或两者兼而有之；以及(B)该网络与其他肥大刺激激活的相关基因调控通路存在显著差异，包括那些通过不同机制涉及细胞内游离钙增加的信号通路。
We showed before that in neonatal rat cardiac myocytes partial inhibition of Na+/K+-ATPase by nontoxic concentrations of ouabain causes hypertrophic growth and transcriptional regulations of genes that are markers of cardiac hypertrophy, In view of the suggested roles of Ras and p42/44 mitogen-activated protein kinases (MAPKs) as key mediators of cardiac hypertrophy, the aim of this work was to explore their roles in ouabain-initiated signal pathways regulating four growth-related genes of these myocytes, i.e. these for c-Fos, skeletal alpha-actin, atrial natriuretic factor, and the alpha(3)-subunit of Na+/K+-ATPase, Ouabain caused rapid activations of Ras and p42/44 MAPKs; the latter was sustained longer than 90 min. Using high efficiency adenoviral-mediated expression of a dominant-negative Ras mutant, and a specific inhibitor of MAPK kinase (MEK), activation of Ras-Raf-MEK-p42/44 MAPK cascade by ouabain was shown. The effects of the mutant Ras, an inhibitor of Ras farnesylation, and the MEK inhibitor on ouabain-in duced changes in mRNAs of the four genes indicated that (a) skeletal alpha-actin induction was dependent on Rat; but not on p42/44 MAPKs, (b) alpha(3) repression was depend ent on the Ras-p42/44 MAPK cascade, and (c) induction of c-fos or atrial natriuretic factor gene occurred partly through the Ras-p42/44 MAPK cascade, and partly through pathways independent of Ras and p42/44 MAPKs, All ouabain effects required extracellular Ca2+ and were attenuated by a Ca2+/calmodulin antagonist or a protein kinase C inhibitor. The findings show that (a) signal pathways linked to sarcolemmal Na+/K+-ATPase share early segments involving Ca2+ and protein kinase C, but diverge into multiple branches only some of which involve Pas, or p42/44 MAPKs, or both; and (b) there are significant differences between this network and the related gene regulatory pathways activated by other hypertrophic stimuli, including those whose responses involve increases in intracellular free Ca2+ through different mechanisms.