Department of Medicine, National Jewish Health, Denver, CO, United States.
Department of Medicine, National Jewish Health, Denver, CO, United States.
Biochem Biophys Res Commun. 2019 Jun 11;513(4):794-799. doi: 10.1016/j.bbrc.2019.04.070. Epub 2019 Apr 16.
A clear understanding of the mechanisms that regulate the alveolar epithelium's barrier is critical to develop new therapeutic strategies to mitigate lung injury. The HER2/HER3 receptor tyrosine kinase complex plays a central role in maintaining the alveolar-capillary barrier. This receptor complex is activated by its ligand, neuregulin-1 (NRG-1). Interleukin-6 (IL-6) is also known to induce HER2 signaling through HER2 transphosphorylation by the IL-6 receptor (IL-6R) complex (1). Due to this interaction, we hypothesized that NRG-1 and IL-6 cooperatively interacted to activate the HER2/HER3 complex. Studies were performed in cultured pulmonary epithelial cells measuring the HER2/IL-6/IL-6R/GP130 interaction and receptor activation by western blotting and confocal microscopy, IL-6 production by ELISA, and IL-6 inhibition using specific antibodies, small molecule inhibitors and shRNA. We found that IL-6 was required for NRG-1 induced activation of HER2 in pulmonary epithelial cells. IL-6 inhibition led to a decrease in NRG-1 induced HER2 activation. The IL-6R and GP130, a subunit of the IL-6R complex, were physically associated with HER2 and were required for NRG-1 induced HER2 activation. Inhibition of GP130, the β-subunit of the IL-6 receptor decreased NRG-1 induced HER2 activation lower than control by 38% Finally, HER2 activation increased IL-6 secretion more than two-fold over resting cells (526 ± 131 vs 231 ± 39.7 pg/ml), and inhibition of HER2 gene expression decreased basal IL-6 secretion over 80% (89 + 4.6 vs 1.3 + 0.8 pg/ml). These findings identify a requirement for IL-6 and the IL-6R complex to allow NRG-1 mediated HER2 activation, and a HER2 driven IL-6 production feedback loop.
清楚了解调节肺泡上皮屏障的机制对于开发新的治疗策略以减轻肺损伤至关重要。HER2/HER3 受体酪氨酸激酶复合物在维持肺泡毛细血管屏障中起着核心作用。该受体复合物通过其配体神经调节蛋白-1（NRG-1）激活。白细胞介素-6（IL-6）也已知通过 IL-6 受体（IL-6R）复合物（1）使 HER2 发生转磷酸化而诱导 HER2 信号传导。由于这种相互作用，我们假设 NRG-1 和 IL-6 合作相互作用以激活 HER2/HER3 复合物。在培养的肺上皮细胞中进行了研究，通过 Western blot 和共聚焦显微镜测量 HER2/IL-6/IL-6R/GP130 相互作用和受体激活，通过 ELISA 测量 IL-6 产生，以及使用特异性抗体、小分子抑制剂和 shRNA 抑制 IL-6。我们发现 IL-6 是 NRG-1 诱导肺上皮细胞中 HER2 激活所必需的。IL-6 抑制导致 NRG-1 诱导的 HER2 激活减少。IL-6R 和 GP130 是 IL-6R 复合物的一个亚基，与 HER2 物理相关，并且是 NRG-1 诱导的 HER2 激活所必需的。GP130 抑制，IL-6 受体的β亚基使 NRG-1 诱导的 HER2 激活比对照降低 38%。最后，HER2 激活使 IL-6 分泌比静息细胞增加两倍以上（526±131 与 231±39.7 pg/ml），HER2 基因表达抑制使基础 IL-6 分泌降低 80%以上（89±4.6 与 1.3±0.8 pg/ml）。这些发现确定了 IL-6 和 IL-6R 复合物允许 NRG-1 介导的 HER2 激活的需求，以及 HER2 驱动的 IL-6 产生反馈回路。
