Center for Global Health, Key Laboratory of Modern Toxicology of Ministry of Education, Department of Occupational Medical and Environmental Health, School of Public Health, Nanjing Medical University, Nanjing 211166, China.
Int J Biol Sci. 2021 Jun 4;17(9):2294-2307. doi: 10.7150/ijbs.57915. eCollection 2021.
Pulmonary fibrosis develops when myofibroblasts and extracellular matrix excessively accumulate in the injured lung, but what drives fibrosis is not fully understood. Glycolysis has been linked to cell growth and proliferation, and several studies have shown enhanced glycolysis promotes pulmonary fibrosis. However, detailed studies describing this switch remain limited. Here, we identified that TGF-β1 effectively increased the expression of circHIPK3 in lung fibroblasts, and circHIPK3 inhibition attenuated the activation, proliferation, and glycolysis of fibroblasts . Dual-luciferase reporter gene assays, RNA immunoprecipitation (RIP), and RNA pull-down assays showed that circHIPK3 could function as a sponge of miR-30a-3p and inhibit its expression. Furthermore, FOXK2, a driver transcription factor of glycolysis, was identified to be a direct target of miR-30a-3p. Mechanistically, circHIPK3 could enhance the expression of FOXK2 via sponging miR-30a-3p, thereby facilitating fibroblast glycolysis and activation. Besides, miR-30a-3p overexpression or FOXK2 knockdown blocked fibroblast activation induced by TGF-β1 and abrogated the profibrotic effects of circHIPK3. Moreover, circHIPK3 and miR-30a-3p were also dysregulated in fibrotic murine lung tissues induced by silica. Adeno-associated virus (AAV)-mediated circHIPK3 silence or miR-30a-3p overexpression alleviated silica-induced pulmonary fibrosis . In conclusion, our results identified circHIPK3/miR-30a-3p/FOXK2 regulatory pathway as an important glycolysis cascade in pulmonary fibrosis.
肺纤维化是在损伤的肺中肌成纤维细胞和细胞外基质过度积聚时发生的，但导致纤维化的原因尚未完全清楚。糖酵解与细胞生长和增殖有关，几项研究表明，增强糖酵解可促进肺纤维化。然而，描述这种转变的详细研究仍然有限。在这里，我们发现 TGF-β1 可有效增加肺成纤维细胞中环状 HIPK3(circHIPK3)的表达，而 circHIPK3 抑制可减弱成纤维细胞的激活、增殖和糖酵解。双荧光素酶报告基因检测、RNA 免疫沉淀（RIP）和 RNA 下拉实验表明，circHIPK3 可以作为 miR-30a-3p 的海绵体并抑制其表达。此外，FOXK2，一种糖酵解的驱动转录因子，被鉴定为 miR-30a-3p 的直接靶标。机制上，circHIPK3 可通过海绵 miR-30a-3p 增强 FOXK2 的表达，从而促进成纤维细胞糖酵解和激活。此外，miR-30a-3p 的过表达或 FOXK2 的敲低可阻断 TGF-β1 诱导的成纤维细胞激活，并消除 circHIPK3 的促纤维化作用。此外，circHIPK3 和 miR-30a-3p 在二氧化硅诱导的纤维化小鼠肺组织中也失调。腺相关病毒（AAV）介导的 circHIPK3 沉默或 miR-30a-3p 的过表达可减轻二氧化硅诱导的肺纤维化。总之，我们的研究结果确定了 circHIPK3/miR-30a-3p/FOXK2 调控通路作为肺纤维化中重要的糖酵解级联反应。
