Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
J Pathol. 2013 Jan;229(2):286-97. doi: 10.1002/path.4131. Epub 2012 Dec 3.
Fibroblasts and myofibroblasts are the key effector cells executing physiological tissue repair leading to regeneration on the one hand, and pathological fibrogenesis leading to chronic fibrosing conditions on the other. Recent studies identify the multifunctional transcription factor early growth response-1(Egr-1) as an important mediator of fibroblast activation triggered by diverse stimuli. Egr-1 has potent stimulatory effects on fibrotic gene expression, and aberrant Egr-1 expression or function is associated with animal models of fibrosis and human fibrotic disorders, including emphysema, pulmonary fibrosis, pulmonary hypertension and systemic sclerosis. Pharmacological suppression or genetic targeting of Egr-1 blocks fibrotic responses in vitro and ameliorates experimental fibrosis in the skin and lung. In contrast, Egr-1 appears to act as a negative regulator of hepatic fibrosis in mouse models, suggesting a context-dependent role in fibrosis. The Egr-1-binding protein Nab2 is an endogenous inhibitor of Egr-1-mediated signalling and abrogates the stimulation of fibrotic responses induced by transforming growth factor-β (TGFβ). Moreover, mice deficient in Nab2 show excessive collagen accumulation in the skin. These observations highlight a previously unsuspected fundamental physiological function for the Egr-1-Nab2 signalling axis in regulating fibrogenesis, and suggest that Egr-1 may be a potential novel therapeutic target in human diseases complicated by fibrosis. This review summarizes recent advances in understanding the regulation and complex functional role of Egr-1 and its related proteins and inhibitors in pathological fibrosis.
成纤维细胞和肌成纤维细胞是执行生理组织修复的关键效应细胞,一方面导致再生,另一方面导致病理性纤维化导致慢性纤维化状态。最近的研究表明,多功能转录因子早期生长反应因子-1(Egr-1)是多种刺激触发成纤维细胞激活的重要介质。Egr-1 对纤维化基因表达具有强烈的刺激作用,异常的 Egr-1 表达或功能与纤维化动物模型和人类纤维化疾病相关,包括肺气肿、肺纤维化、肺动脉高压和系统性硬化症。Egr-1 的药理学抑制或基因靶向阻断了体外纤维化反应,并改善了皮肤和肺的实验性纤维化。相比之下,Egr-1 似乎在小鼠模型中作为肝纤维化的负调节剂发挥作用,提示其在纤维化中具有上下文依赖性作用。Egr-1 结合蛋白 Nab2 是 Egr-1 介导的信号的内源性抑制剂,并消除转化生长因子-β(TGFβ)诱导的纤维化反应的刺激。此外,缺乏 Nab2 的小鼠在皮肤中表现出过多的胶原积累。这些观察结果突出了 Egr-1-Nab2 信号轴在调节纤维化方面的先前未被怀疑的基本生理功能,并表明 Egr-1 可能是人类纤维化疾病的潜在新的治疗靶点。本文综述了最近在理解 Egr-1 及其相关蛋白和抑制剂在病理性纤维化中的调节和复杂功能作用方面的进展。