The NAD(P)H oxidase homolog Nox4 modulates insulin-stimulated generation of H2O2 and plays an integral role in insulin signal transduction
The NAD(P)H oxidase homolog Nox4 modulates insulin-stimulated generation of H2O2 and plays an integral role in insulin signal transduction
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DOI：
10.1128/mcb.24.5.1844-1854.2004
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发表时间：
2004-03-01
影响因子：
5.3
通讯作者：
Goldstein, BJ
中科院分区：
文献类型：
--
作者：
Mahadev, K;Motoshima, H;Goldstein, BJ
靶细胞的胰岛素刺激引起H2 O2爆发，其增强胰岛素受体及其细胞底物蛋白的酪氨酸磷酸化以及胰岛素作用级联中的远端信号传导事件。胰岛素受体与细胞氧化剂产生装置的分子机制尚未阐明。通过逆转录-PCR和北方印迹分析，我们发现，Nox 4，一个同源的gp 91 phox，吞噬NAD（P）H氧化酶催化亚基，显着表达在胰岛素敏感的脂肪细胞。腺病毒介导的缺失NAD（P）H或FAD/NAD（P）H辅因子结合域的Nox 4缺失构建体的表达在分化的3 T3-L1脂肪细胞中以显性负性方式起作用，并减弱胰岛素刺激的H2 O2产生、胰岛素受体（IR）和IRS-1酪氨酸磷酸化、下游丝氨酸激酶的活化和葡萄糖摄取。特异性小干扰RNA寡核苷酸的转染降低了Nox 4蛋白的丰度，也抑制了胰岛素信号级联反应。Nox 4的过表达还通过抑制PTP 1B的催化活性显著逆转了PTP 1B共表达诱导的胰岛素刺激的IR酪氨酸磷酸化的抑制。这些数据表明，Nox 4提供了一个新的IR和细胞活性氧的产生之间的联系，增强胰岛素信号转导，至少部分通过氧化抑制细胞蛋白酪氨酸磷酸酶（PTPases），包括PTP 1B，PTPases，以前已经牵连在胰岛素作用的调节。
Insulin stimulation of target cells elicits a burst of H2O2 that enhances tyrosine phosphorylation of the insulin receptor and its cellular substrate proteins as well as distal signaling events in the insulin action cascade. The molecular mechanism coupling the insulin receptor with the cellular oxidant-generating apparatus has not been elucidated. Using reverse transcription-PCR and Northern blot analyses, we found that Nox4, a homolog of gp91phox, the phagocytic NAD(P)H oxidase catalytic subunit, is prominently expressed in insulin-sensitive adipose cells. Adenovirus-mediated expression of Nox4 deletion constructs lacking NAD(P)H or FAD/NAD(P)H cofactor binding domains acted in a dominant-negative fashion in differentiated 3T3-L1 adipocytes and attenuated insulin-stimulated H2O2 generation, insulin receptor (IR) and IRS-1 tyrosine phosphorylation, activation of downstream serine kinases, and glucose uptake. Transfection of specific small interfering RNA oligonucleotides reduced Nox4 protein abundance and also inhibited the insulin signaling cascade. Overexpression of Nox4 also significantly reversed the inhibition of insulin-stimulated IR tyrosine phosphorylation induced by coexpression of PTP1B by inhibiting PTP1B catalytic activity. These data suggest that Nox4 provides a novel link between the IR and the generation of cellular reactive oxygen species that enhance insulin signal transduction, at least in part via the oxidative inhibition of cellular protein-tyrosine phosphatases (PTPases), including PTP1B, a PTPase that has been previously implicated in the regulation of insulin action.