Klotz L O, Schieke S M, Sies H, Holbrook N J
Cell Stress and Aging Section, Laboratory of Biological Chemistry, National Institute on Aging, National Institutes of Health, 5600 Nathan Shock Drive, Baltimore, MD 21224-6825, USA.
Biochem J. 2000 Nov 15;352 Pt 1(Pt 1):219-25.
Peroxynitrite is a potent oxidizing and nitrating species formed in a diffusion-limited reaction between nitrogen monoxide and superoxide. It induces apoptosis through unknown mechanisms and is believed to interfere with receptor tyrosine kinase signalling through nitration of tyrosine residues. One pathway emanating from receptor tyrosine kinases is that leading to activation of the anti-apoptotic kinase Akt. In the present study we provide evidence that peroxynitrite, administered to cells using two different delivery systems, results in the dose- and time-dependent activation of Akt. Akt activation is rapid and followed by phosphorylation of glycogen synthase kinase-3, an established substrate of Akt. Akt activation is inhibited in the presence of the phosphoinositide 3-kinase (PI-3K) inhibitors wortmannin and LY294002, and by treatment with the platelet-derived growth factor (PDGF) receptor (PDGFR) inhibitor AG1295, indicating a requirement for PDGFR and PI-3K in mediating peroxynitrite-induced Akt activation. Accordingly, the PDGFR-A and PDGFR-B isoforms were shown to undergo rapid tyrosine phosphorylation on treatment with peroxynitrite. Prior exposure of cells to peroxynitrite interferes with PDGF-induced Akt phosphorylation. Our findings suggest that Akt activation occurs as an acute response to peroxynitrite treatment and could play an important role in influencing cell survival and/or alter the cellular response to other growth regulatory signals.
过氧亚硝酸盐是一氧化氮和超氧化物之间在扩散限制反应中形成的一种强效氧化和硝化物质。它通过未知机制诱导细胞凋亡，并且据信通过酪氨酸残基的硝化作用干扰受体酪氨酸激酶信号传导。源自受体酪氨酸激酶的一条信号通路是导致抗凋亡激酶Akt激活的通路。在本研究中，我们提供证据表明，使用两种不同的递送系统将过氧亚硝酸盐施用于细胞，会导致Akt呈剂量和时间依赖性激活。Akt激活迅速，随后糖原合酶激酶-3（Akt的一个既定底物）发生磷酸化。在存在磷酸肌醇3激酶（PI-3K）抑制剂渥曼青霉素和LY294002的情况下，以及用血小板衍生生长因子（PDGF）受体（PDGFR）抑制剂AG1295处理时，Akt激活受到抑制，这表明在介导过氧亚硝酸盐诱导的Akt激活中需要PDGFR和PI-3K。因此，过氧亚硝酸盐处理后，PDGFR-A和PDGFR-B亚型显示出快速的酪氨酸磷酸化。细胞预先暴露于过氧亚硝酸盐会干扰PDGF诱导的Akt磷酸化。我们的研究结果表明，Akt激活是对过氧亚硝酸盐处理的一种急性反应，并且在影响细胞存活和/或改变细胞对其他生长调节信号的反应中可能起重要作用。
