Nox4 NAD(P)H oxidase mediates Src-dependent tyrosine phosphorylation of PDK-1 in response to angiotensin II - Role in mesangial cell hypertrophy and fibronectin expression
Nox4 NAD(P)H oxidase mediates Src-dependent tyrosine phosphorylation of PDK-1 in response to angiotensin II - Role in mesangial cell hypertrophy and fibronectin expression
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DOI：
10.1074/jbc.m803964200
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发表时间：
2008-08-29
影响因子：
4.8
通讯作者：
Gorin, Yves
中科院分区：
文献类型：
--
作者：
Block, Karen;Eid, Assaad;Gorin, Yves
血管紧张素II(Ang II)激活肾小球系膜细胞(MC)导致肥大和细胞外基质堆积。在这里，我们证明，在MC中，Ang II诱导PDK-1(3-磷酸肌醇依赖的蛋白激酶-1)活性增加，这需要它对酪氨酸9和373/376进行磷酸化。将这些酪氨酸残基突变的PDK-1导入细胞，或使其失去活性，可减弱血管紧张素转换酶II诱导的肥大和纤维连接蛋白的积聚。Ang II介导的PDK-1活化和酪氨酸磷酸化(总的第9位和第373/376位残基)在细胞中被抑制，表明Src位于PDK-1的上游。在表达抗氧化性Src突变体C487A的细胞中，Ang II诱导的肥大和纤维连接蛋白的表达被阻止，这表明该途径是氧化还原敏感的。Ang II还上调NOX4蛋白，siNox4可抑制Ang II诱导的细胞内活性氧(ROS)生成增加。针对NOX4的小干扰RNA还抑制Ang II诱导的Src和PDK-1酪氨酸磷酸化的激活(总的和残基9和373/376)，表明NOX4在Src和PDK-1的上游发挥作用。重要的是，抑制NOX4、Src或PDK-1可以阻止Ang II对纤维连接蛋白积聚和细胞肥大的刺激作用。这项工作首次证明了NOX4来源的ROS参与了Ang II诱导的PDK-1酪氨酸的磷酸化和通过刺激Src而激活。重要的是，这一途径有助于血管紧张素II诱导的MC肥大和纤维连接蛋白的积聚。这些数据揭示了Ang II参与的氧化信号级联的潜在分子过程，并确定了预防肾脏肥大和纤维化的潜在干预靶点。
Activation of glomerular mesangial cells (MCs) by angiotensin II (Ang II) leads to hypertrophy and extracellular matrix accumulation. Here, we demonstrate that, in MCs, Ang II induces an increase in PDK-1 (3-phosphoinositide-dependent protein kinase-1) kinase activity that required its phosphorylation on tyrosine 9 and 373/376. Introduction into the cells of PDK-1, mutated on these tyrosine residues or kinase-inactive, attenuates Ang II-induced hypertrophy and fibronectin accumulation. Ang II-mediated PDK-1 activation and tyrosine phosphorylation ( total and on residues 9 and 373/376) are inhibited in cells transfected with small interfering RNA for Src, indicating that Src is upstream of PDK-1. In cells expressing oxidation-resistant Src mutant C487A, Ang II-induced hypertrophy and fibronectin expression are prevented, suggesting that the pathway is redox-sensitive. Ang II also up-regulates Nox4 protein, and siNox4 abrogates the Ang II-induced increase in intracellular reactive oxygen species (ROS) generation. Small interfering RNA for Nox4 also inhibits Ang II-induced activation of Src and PDK-1 tyrosine phosphorylation ( total and on residues 9 and 373/376), demonstrating that Nox4 functions upstream of Src and PDK-1. Importantly, inhibition of Nox4, Src, or PDK-1 prevents the stimulatory effect of Ang II on fibronectin accumulation and cell hypertrophy. This work provides the first evidence that Nox4-derived ROS are responsible for Ang II-induced PDK-1 tyrosine phosphorylation and activation through stimulation of Src. Importantly, this pathway contributes to Ang II-induced MC hypertrophy and fibronectin accumulation. These data shed light on molecular processes underlying the oxidative signaling cascade engaged by Ang II and identify potential targets for intervention to prevent renal hypertrophy and fibrosis.