Gα12/13-mediated production of reactive oxygen species is critical for angiotensin receptor-induced NFAT activation in cardiac fibroblasts
Gα12/13-mediated production of reactive oxygen species is critical for angiotensin receptor-induced NFAT activation in cardiac fibroblasts
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DOI：
10.1074/jbc.m409397200
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发表时间：
2005-06-17
影响因子：
4.8
通讯作者：
Kurose, H
中科院分区：
文献类型：
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作者：
Fujii, T;Onohara, N;Kurose, H
血管紧张素II(Ang II)激活多条信号通路，导致心脏成纤维细胞增殖。血管紧张素Ⅱ刺激产生的活性氧(ROS)被认为在这一过程中起关键作用。在这里，我们发现ROS介导了Ang II诱导的大鼠心脏成纤维细胞中活化T细胞核因子(NFAT)的激活。血管紧张素Ⅱ诱导的NFAT活化可被NADPH氧化酶抑制剂二苯基碘、显性负性(DN)-RAC、dN-p47(Phox)和Gβ(12/13)(Gα(12/13)特异性调节蛋白信号转导结构域p115-G蛋白信号转导调节蛋白(RGS))所抑制。刺激血管紧张素Ⅱ受体可增加细胞内ROS水平，且呈RAC和P47(Phox)依赖性。由于p115-RGS抑制Ang II诱导的RAC激活，Ang II受体偶联Gα(12/13)通过RAC激活产生ROS来介导NFAT的激活。P115-RGS或BAPTA可抑制Ang II诱导的绿色荧光蛋白(GFP)标记的NFAT4氨基末端区域(GFP-NFAT4)的核转位，但不能被二苯碘抑制。成分活性(CA)-Gα(12)、CA-Gα(13)或CA-RAC的表达增加了GFP-NFAT4的核转位。这些结果表明，NFAT活性受钙依赖和ROS依赖两种途径的调节。此外，血管紧张素Ⅱ诱导的NFAT激活需要激活c-Jun氨基末端激酶(JNK)，因为选择性的JNK抑制剂SP600125抑制了Ang II诱导的NFAT激活。这些结果表明，Ang II通过激活Gα(12/13)、RAC、NADPH氧化酶和JNK等多种途径刺激NFAT的核转位和激活，Gα(12/13)介导的ROS的产生是NFAT转录激活所必需的。
Angiotensin II (Ang II) activates multiple signaling pathways leading to hyperplasia of cardiac fibroblasts. Reactive oxygen species (ROS) produced by Ang II stimulation are assumed to play pivotal roles in this process. Here, we show that ROS mediate Ang II-induced activation of nuclear factor of activated T cells (NFAT) in rat cardiac fibroblasts. Ang II-induced NFAT activation was suppressed by diphenyleneiodonium (an NADPH oxidase inhibitor), dominant negative (DN)-Rac, DN-p47(phox), and an inhibitor of G beta(12/13) (G alpha(12/13)-specific regulator of G protein signaling domain of p115RhoGEF, p115-regulator of G protein signaling (RGS)). Stimulation of Ang II receptor increased the intracellular ROS level in a Rac- and p47(phox)-dependent manner. Because p115-RGS suppressed Ang II-induced Rac activation, Ang II receptor-coupled G alpha(12/13) mediated NFAT activation through ROS production by Rac activation. Ang II-induced nuclear translocation of the green fluorescent protein (GFP)-tagged amino-terminal region of NFAT4 (GFP-NFAT4) was suppressed by p115-RGS or BAPTA but not by diphenyleneiodonium. The expression of constitutively active (CA)-G alpha(12), CA-G alpha(13), or CA-Rac increased the nuclear translocation of GFP-NFAT4. These results suggest that NFAT activity is regulated by both Ca2+-dependent and ROS-dependent pathways. Furthermore, activation of c-Jun NH2-terminal kinase (JNK) induced by Ang II stimulation is required for NFAT activation because Ang II-induced NFAT activation was inhibited by SP600125, a selective JNK inhibitor. These results indicate that Ang II stimulates the nuclear translocation and activation of NFAT by integrated pathways including the activation of G alpha(12/13), Rac, NADPH oxidase, and JNK and that G alpha(12/13)-mediated ROS production is essential for NFAT transcriptional activation.