Pulmonary fibrosis is a progressive and lethal lung disease characterized by the proliferation and differentiation of lung fibroblasts and the accumulation of extracellular matrices. Since pulmonary fibrosis was reported to be associated with adenosine monophosphate-activated protein kinase (AMPK) activation, which is negatively regulated by cereblon (CRBN), we aimed to determine whether CRBN is involved in the development of pulmonary fibrosis. Therefore, we evaluated the role of CRBN in bleomycin (BLM)-induced pulmonary fibrosis in mice and in transforming growth factor-beta 1 (TGF-β1)-induced differentiation of human lung fibroblasts. BLM-induced fibrosis and the mRNA expression of collagen and fibronectin were increased in the lung tissues of wild-type (WT) mice; however, they were significantly suppressed in Crbn knockout (KO) mice. While the concentrations of TGF-β1/2 in bronchoalveolar lavage fluid were increased via BLM treatment, they were similar between BLM-treated WT and Crbn KO mice. Knockdown of CRBN suppressed TGF-β1-induced activation of small mothers against decapentaplegic 3 (SMAD3), and overexpression of CRBN increased it. TGF-β1-induced activation of SMAD3 increased α-smooth muscle actin (α-SMA) and collagen levels. CRBN was found to be colocalized with AMPKα1 in lung fibroblasts. CRBN overexpression inactivated AMPKα1. When cells were treated with metformin (an AMPK activator), the CRBN-induced activation of SMAD3 and upregulation of α-SMA and collagen expression were significantly suppressed, suggesting that increased TGF-β1-induced activation of SMAD3 via CRBN overexpression is associated with AMPKα1 inactivation. Taken together, these data suggest that CRBN is a profibrotic regulator and maybe a potential target for treating lung fibrosis.

肺纤维化是一种进行性和致命的肺部疾病，其特征是肺成纤维细胞的增殖和分化以及细胞外基质的积累。由于据报道肺纤维化与腺苷一磷酸活化蛋白激酶 (AMPK) 激活有关，而腺苷一磷酸活化蛋白激酶 (AMPK) 受 cereblon (CRBN) 负调控，我们旨在确定 CRBN 是否参与肺纤维化的发展。因此，我们评估了 CRBN 在博莱霉素 (BLM) 诱导的小鼠肺纤维化和转化生长因子-β1 (TGF-β1) 诱导的人肺成纤维细胞分化中的作用。野生型（WT）小鼠肺组织中 BLM 诱导的纤维化和胶原蛋白和纤连蛋白的 mRNA 表达增加；然而，它们在Crbn中被显着抑制敲除（KO）小鼠。虽然通过 BLM 处理增加了支气管肺泡灌洗液中 TGF-β1/2 的浓度，但它们在 BLM 处理的 WT 和Crbn之间是相似的KO小鼠。敲除 CRBN 抑制了 TGF-β1 诱导的小母体对 decapentaplegic 3 (SMAD3) 的激活，并且 CRBN 的过表达增加了它。TGF-β1 诱导的 SMAD3 激活增加了 α-平滑肌肌动蛋白 (α-SMA) 和胶原蛋白水平。发现 CRBN 与肺成纤维细胞中的 AMPKα1 共定位。CRBN 过表达使 AMPKα1 失活。当用二甲双胍（一种 AMPK 激活剂）处理细胞时，CRBN 诱导的 SMAD3 激活以及 α-SMA 和胶原蛋白表达的上调被显着抑制，这表明通过 CRBN 过表达增加 TGF-β1 诱导的 SMAD3 激活与 AMPKα1 相关。失活。总之，这些数据表明 CRBN 是一种促纤维化调节剂，可能是治疗肺纤维化的潜在靶点。