表皮生长因子受体(EGFR)激活的信号传导和肌动蛋白重塑调节周期性拉伸诱导的核因子E2相关因子2-抗氧化反应元件(NRF2-ARE)激活。

EGFR-activated signaling and actin remodeling regulate cyclic stretch-induced NRF2-ARE activation.

作者信息

Papaiahgari Srinivas, Yerrapureddy Adinarayana, Hassoun Paul M, Garcia Joe G N, Birukov Konstantin G, Reddy Sekhar P

机构信息

Division of Physiology, Department of Environmental Health Sciences, The Johns Hopkins Medical Institutions, Baltimore, Maryland 21205, USA.

出版信息

Am J Respir Cell Mol Biol. 2007 Mar;36(3):304-12. doi: 10.1165/rcmb.2006-0131OC. Epub 2006 Sep 28.

Abstract

Cyclic stretch (CS) associated with mechanical ventilation (MV) can cause excessive alveolar and endothelial distention, resulting in lung injury and inflammation. Antioxidant enzymes (AOEs) play a major role in suppressing these effects. The transcription factor Nrf2, via the antioxidant response element (ARE), alleviates pulmonary toxicant- and oxidant-induced oxidative stress by up-regulating the expression of several AOEs. Although gene expression profiling has revealed the induction of AOEs in the lungs of rodents exposed to MV, the mechanisms by which mechanical forces, such as CS, regulate the activation of Nrf2-dependent ARE-transcriptional responses are poorly understood. To mimic mechanical stress associated with MV, we have cultured pulmonary alveolar epithelial and endothelial cells on collagen I-coated BioFlex plates and subjected them to CS. CS exposure stimulated ARE-driven transcriptional responses and subsequent AOE expression. Ectopic expression of a dominant-negative Nrf2 suppressed the CS-stimulated ARE-driven responses. Our findings suggest that actin remodeling is necessary but not sufficient for high-level CS-induced ARE activation in both epithelial and endothelial cells. We also found that inhibition of EGFR activity by a pharmacologic agent ablated the CS-induced ARE transcriptional response in both cell types. Additional studies revealed that amphiregulin, an EGFR ligand, regulates this process. We further demonstrated that the PI3K-Akt pathway acts as the downstream effector of EGFR and regulates CS-induced ARE-activation in an oxidative stress-dependent manner. Collectively, these novel findings suggest that EGFR-activated signaling and actin remodeling act in concert to regulate the CS-induced Nrf2-ARE transcriptional response and subsequent AOE expression.

摘要

与机械通气(MV)相关的周期性拉伸(CS)可导致肺泡和内皮过度扩张,从而引起肺损伤和炎症。抗氧化酶(AOE)在抑制这些影响中起主要作用。转录因子Nrf2通过抗氧化反应元件(ARE),上调几种AOE的表达,从而减轻肺部毒物和氧化剂诱导的氧化应激。尽管基因表达谱分析显示,暴露于MV的啮齿动物肺中AOE被诱导,但诸如CS等机械力调节Nrf2依赖性ARE转录反应激活的机制仍知之甚少。为了模拟与MV相关的机械应力,我们将肺泡上皮细胞和内皮细胞培养在I型胶原包被的BioFlex板上,并对其施加CS。CS暴露刺激了ARE驱动的转录反应以及随后的AOE表达。显性负性Nrf2的异位表达抑制了CS刺激的ARE驱动反应。我们的研究结果表明,肌动蛋白重塑对于上皮细胞和内皮细胞中高水平CS诱导的ARE激活是必要的,但并不充分。我们还发现,用药物抑制EGFR活性可消除两种细胞类型中CS诱导的ARE转录反应。进一步的研究表明,EGFR配体双调蛋白调节这一过程。我们进一步证明,PI3K-Akt途径作为EGFR的下游效应器,以氧化应激依赖性方式调节CS诱导的ARE激活。总的来说,这些新发现表明,EGFR激活的信号传导和肌动蛋白重塑协同作用,调节CS诱导的Nrf2-ARE转录反应以及随后的AOE表达。

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