MicroRNAs (miRNAs) is involved in diverse biological processes of cells including dermal fibroblasts that contributed to wound healing and resulted in keloid scarring. MiR-506-3p has been identified as a tumor suppressor or oncogene in fibroblasts of various cancers, while the role of miR-506-3p in regulating functions of post-burn dermal fibroblasts is poorly known. In this study, miR-506-3p was confirmed to be significantly downregulated in burned tissues and heat-stimulated dermal fibroblasts. Expression levels of autophagy-related proteins suggested thermal stimulus promoting the autophagy in dermal fibroblasts. Then, miR-506-3p inhibition enhanced cell proliferation and cell cycle process in dermal fibroblasts after thermal stimulus, whereas overexpression of miR-506-3p showed the opposite effect. Western blot assay showed that inhibition of miR-506-3p resulted in the upregulation of the expression levels of LC3-II, ATG5, and structural protein collagen I, as well as the downregulation of p62. Marker proteins of intermolecular cross-links in collagen synthesis, including hydroxylysylpyridinoline (HP), lysinepyridine (LP), and lysyl hydroxylase 2 (LH2), were increased by miR-506-3p overexpression and decreased by miR-506-3p inhibition. Moreover, transfection with miR-506-3p mimic suppressed the proliferation and autophagy in heat-stimulated dermal fibroblasts in a dose-dependent manner. Subsequently, dual luciferase reporter gene assay demonstrated that Beclin-1 was a direct target of miR-506-3p, and reintroduction of Beclin-1 could antagonize the suppressive effect of miR-506-3p overexpression on fibroblast proliferation, autophagy, and the intermolecular cross-links in collagen synthesis. Taken together, our findings showed that miR-506-3p regulated autophagy and proliferation in post-burn skin fibroblasts through post-transcriptionally suppressing Beclin-1 expression.

MicroRNA（miRNA）参与细胞的各种生物学过程，包括真皮成纤维细胞，这些过程有助于伤口愈合并导致瘢痕瘢痕形成。在各种癌症的成纤维细胞中，MiR-506-3p被鉴定为肿瘤抑制因子或致癌基因，而人们对miR-506-3p在调节烧伤后皮肤成纤维细胞功能中的作用却知之甚少。在这项研究中，证实miR-506-3p在烧伤的组织和热刺激的真皮成纤维细胞中显着下调。自噬相关蛋白的表达水平表明，热刺激促进了真皮成纤维细胞中的自噬。然后，在热刺激后，miR-506-3p抑制作用增强了皮肤成纤维细胞的细胞增殖和细胞周期过程，而miR-506-3p的过表达则显示相反的作用。蛋白质印迹分析表明，抑制miR-506-3p会导致LC3-II，ATG5和结构蛋白胶原I的表达水平上调，以及p62的下调。miR-506-3p过表达会增加胶原合成过程中分子间交联的标记蛋白，包括羟基赖氨酰吡啶（HP），赖氨酸吡啶（LP）和赖氨酰羟化酶2（LH2），而受miR-506-3p抑制作用会降低。此外，miR-506-3p模拟物的转染以剂量依赖的方式抑制了热刺激的真皮成纤维细胞的增殖和自噬。随后，双重荧光素酶报告基因检测证明Beclin-1是miR-506-3p的直接靶标，并且重新导入Beclin-1可以拮抗miR-506-3p过表达对成纤维细胞增殖，自噬，以及胶原合成中的分子间交联。综上所述，我们的发现表明，miR-506-3p通过转录后抑制Beclin-1的表达来调节烧伤后皮肤成纤维细胞中的自噬和增殖。