Department of Disease Control, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan.
Department of Disease Control, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan.
J Biol Chem. 2023 Mar;299(3):102934. doi: 10.1016/j.jbc.2023.102934. Epub 2023 Jan 20.
Fibrosis is mainly triggered by inflammation in various tissues, such as heart and liver tissues, and eventually leads to their subsequent dysfunction. Fibrosis is characterized by the excessive accumulation of extracellular matrix proteins (e.g., collagens) produced by myofibroblasts. The well-developed actin cytoskeleton of myofibroblasts, one of the main features differentiating them from resident fibroblasts in tissues under inflammatory conditions, contributes to maintaining their ability to produce excessive extracellular matrix proteins. However, the molecular mechanisms via which the actin cytoskeleton promotes the production of fibrosis-related genes in myofibroblasts remain unclear. In this study, we found, via single-cell analysis, that developmentally regulated brain protein (drebrin), an actin-binding protein, was specifically expressed in cardiac myofibroblasts with a well-developed actin cytoskeleton in fibrotic hearts. Moreover, our immunocytochemistry analysis revealed that drebrin promoted actin cytoskeleton formation and myocardin-related transcription factor-serum response factor signaling. Comprehensive single-cell analysis and RNA-Seq revealed that the expression of collagen triple helix repeat containing 1 (Cthrc1), a fibrosis-promoting secreted protein, was regulated by drebrin in cardiac myofibroblasts via myocardin-related transcription factor-serum response factor signaling. Furthermore, we observed the profibrotic effects of drebrin exerted via actin cytoskeleton formation and the Cthrc1 expression regulation by drebrin in liver myofibroblasts (hepatic stellate cells). Importantly, RNA-Seq demonstrated that drebrin expression levels increased in human fibrotic heart and liver tissues. In summary, our results indicated that the well-developed actin cytoskeleton and Cthrc1 expression due to drebrin in myofibroblasts promoted cardiac and hepatic fibrosis, suggesting that drebrin is a therapeutic target molecule for fibrosis.
纤维化主要由各种组织（如心脏和肝脏组织）的炎症触发，最终导致其随后的功能障碍。纤维化的特征是肌成纤维细胞过度积累细胞外基质蛋白（例如胶原蛋白）。肌成纤维细胞中发达的肌动蛋白细胞骨架是其与炎症条件下组织中常驻成纤维细胞区分的主要特征之一，有助于维持其产生过多细胞外基质蛋白的能力。然而，肌动蛋白细胞骨架促进肌成纤维细胞中纤维化相关基因产生的分子机制尚不清楚。在这项研究中，我们通过单细胞分析发现，发育调节脑蛋白（drebrin）是一种肌动蛋白结合蛋白，在纤维化心脏中具有发达肌动蛋白细胞骨架的心肌成纤维细胞中特异性表达。此外，我们的免疫细胞化学分析表明，drebrin 促进了肌动蛋白细胞骨架的形成和肌球蛋白相关转录因子-血清反应因子信号转导。综合单细胞分析和 RNA-Seq 揭示，胶原蛋白三螺旋重复序列 1（Cthrc1）的表达受 drebrin 通过肌球蛋白相关转录因子-血清反应因子信号转导在心肌成纤维细胞中的调控。此外，我们观察到 drebrin 通过肌动蛋白细胞骨架形成和 drebrin 对 Cthrc1 表达的调控在肝成纤维细胞（肝星状细胞）中发挥的促纤维化作用。重要的是，RNA-Seq 表明 drebrin 在人纤维化心脏和肝脏组织中的表达水平增加。总之，我们的结果表明，肌成纤维细胞中发达的肌动蛋白细胞骨架和 Cthrc1 表达由于 drebrin 的存在促进了心脏和肝脏纤维化，表明 drebrin 是纤维化的治疗靶点分子。
