EGFR-independent activation of p38 MAPK and EGFR-dependent activation of ERK1/2 are required for ROS-induced renal cell death
EGFR-independent activation of p38 MAPK and EGFR-dependent activation of ERK1/2 are required for ROS-induced renal cell death
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DOI：
10.1152/ajprenal.00132.2004
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发表时间：
2004-11-01
影响因子：
4.2
通讯作者：
Monks, TJ
中科院分区：
文献类型：
--
作者：
Dong, J;Ramachandiran, S;Monks, TJ
2,3,5- tris -（谷胱甘肽- s-酰基）对苯二酚（TGHQ）是肾毒性对苯二酚的一种反应性代谢物，可诱导ros依赖性的MAPKs激活，随后是肾近端小管上皮细胞（lc - pk1）的组蛋白H3磷酸化和肿瘤细胞死亡。药物抑制p38 MAPK或ERK1/2通路可减轻细胞死亡和组蛋白H3磷酸化。由于TGHQ而不是表皮生长因子（EGF）在lc - pk1细胞中诱导组蛋白H3磷酸化和细胞死亡，我们假设TGHQ和EGF诱导EGF受体（EGFR）激活的机制存在差异。因此，我们比较了TGHQ、H2O2和EGF激活EGFR和MAPK的相对能力，发现p38 MAPK的激活与EGFR无关，而ERK1/2的激活主要通过EGFR激活。tgq、H2O2和EGF诱导不同的EGFR酪氨酸磷酸化谱，可能影响随后MAPK活化的差异动力学。接下来，我们用显性负表达p38 mapk的质粒（pcDNA3-DNp38）转染了LLC-PK1细胞。在pcdna3 - dnp38转染的细胞中，tgq未能诱导p38 MAPK及其底物MK-2的磷酸化，表明p38 MAPK的功能丧失。在未转染pcDNA3或pcDNA3-p38（天然）转染的lc - pk1细胞中，TGHQ处理后Hsp27被强烈磷酸化，而在pcDNA3- dnp38转染的细胞中，TGHQ未能诱导Hsp27磷酸化。因此，egfr独立的p38 MAPK和egfr依赖的ERK1/2被TGHQ激活导致两个下游信号因子的激活，即组蛋白H3和Hsp27磷酸化，它们共同具有重塑染色质的潜在能力。
2,3,5-Tris-(glutathion-S-yl) hydroquinone (TGHQ), a reactive metabolite of the nephrotoxicant hydroquinone, induces the ROS-dependent activation of MAPKs, followed by histone H3 phosphorylation and oncotic cell death in renal proximal tubule epithelial cells (LLC-PK1). Cell death and histone H3 phosphorylation are attenuated by pharmacological inhibition of p38 MAPK or ERK1/2 pathways. Because TGHQ, but not epidermal growth factor (EGF), induces histone H3 phosphorylation and cell death in LLC-PK1 cells, we hypothesized that there are differences in the mechanisms by which TGHQ and EGF induce activation of the EGF receptor (EGFR). We therefore compared the relative ability of TGHQ, H2O2, and EGF to activate EGFR and MAPKs and found that p38 MAPK activation is EGFR independent, whereas ERK1/2 activation occurs mainly through EGFR activation. TGHQ, H2O2, and EGF induce different EGFR tyrosine phosphorylation profiles that likely influence the subsequent differential kinetics of MAPK activation. We next transfected LLC-PK1 cells with a dominant negative p38 MAPK-expressing plasmid (pcDNA3-DNp38). TGHQ failed to induce phosphorylation of p38 MAPK and its substrate, MK-2, in pcDNA3-DNp38-transfected cells, indicating loss of function of p38 MAPK. In untransfected, pcDNA3 or pcDNA3-p38 (native)-transfected LLC-PK1 cells, Hsp27 was intensively phosphorylated after TGHQ treatment, whereas in pcDNA3-DNp38-transfected cells, TGHQ failed to induce Hsp27 phosphorylation. Thus EGFR-independent p38 MAPK and EGFR-dependent ERK1/2 activation by TGHQ lead to the activation of two downstream signaling factors, i.e., histone H3 and Hsp27 phosphorylation, which have in common the potential ability to remodel chromatin.