Clinical Research Center of Shaanxi Province for Dental and Maxillofacial Diseases, Department of Preventive Dentistry, College of Stomatology, Xi'an Jiaotong University, 98 Xiwu Road, Xi'an, Shaanxi, 710004, People's Republic of China.
Department of Pediatric Dentistry, College of Stomatology, Xi'an Jiaotong University, 98 Xiwu Road, Xi'an, Shaanxi, 710004, People's Republic of China.
Biomed Pharmacother. 2019 May;113:108742. doi: 10.1016/j.biopha.2019.108742. Epub 2019 Mar 6.
Caries, pulpitis, and trauma are the main causes of dental pulp damage. The regeneration capacity of dental pulp declines with age. Lin28 is a conserved RNA-binding protein in higher eukaryotes that regulates several important cellular functions associated with development, glucose metabolism, differentiation, and pluripotency. Conditional reactivation of Lin28 gene in adult mice markedly accelerates the wound-healing process in injured digits. However, little is known about its functions and molecular mechanism in human dental pulp. The aim of this study was to investigate the effects and mechanism of overexpression of Lin28 gene on the proliferation of human dental pulp cells (HDPCs). For this purpose, a number of molecular and biochemical analytical techniques, including the ethynyl-2'-deoxyuridine (EdU) incorporation assay, RNA-protein immunoprecipitation (RIP) analysis, and luciferase assays, were used for detailed characterization. In addition, factors regulating HDPCs activation were explored through gain-of-function and loss-of-function analyses. The results demonstrate that Lin28 promotes cell proliferation and the S-G2/M transition of HDPCs and directly binds to a group of cell cycle regulatory mRNAs in HDPCs. Through bioinformatics analysis and luciferase assays, we confirmed that let-7a targets IGF2BP2. Silencing of IGF2BP2 showed similar cellular and molecular effects as let-7a. Similarly, restoration of IGF2BP2 counteracted the effects of let-7a expression. In conclusion, Lin28 promotes cell proliferation by regulation of both mRNA translation (let-7-independent) and miRNA biogenesis (let-7-dependent). Lin28 can promote the expression of pro-proliferative genes by directly enhancing their translation to maintain a tight control over HDPC proliferation.
龋病、牙髓炎和创伤是牙髓损伤的主要原因。牙髓的再生能力随着年龄的增长而下降。Lin28 是高等真核生物中一种保守的 RNA 结合蛋白，调节与发育、葡萄糖代谢、分化和多能性相关的几种重要的细胞功能。在成年小鼠中条件性重新激活 Lin28 基因可显著加速损伤指端的伤口愈合过程。然而，关于其在人牙髓中的功能和分子机制知之甚少。本研究旨在探讨 Lin28 基因过表达对人牙髓细胞（HDPC）增殖的影响及其机制。为此，采用了多种分子和生化分析技术，包括乙炔基-2'-脱氧尿苷（EdU）掺入测定、RNA-蛋白免疫沉淀（RIP）分析和荧光素酶测定，对其进行了详细的表征。此外，通过功能获得和功能丧失分析探讨了调节 HDPC 激活的因素。结果表明，Lin28 促进 HDPC 的细胞增殖和 S-G2/M 期转变，并直接与一组细胞周期调节 mRNA 在 HDPC 中结合。通过生物信息学分析和荧光素酶测定，我们证实 let-7a 靶向 IGF2BP2。沉默 IGF2BP2 表现出与 let-7a 相似的细胞和分子效应。同样，IGF2BP2 的恢复抵消了 let-7a 表达的影响。总之，Lin28 通过调节 mRNA 翻译（与 let-7 无关）和 miRNA 生物发生（与 let-7 依赖）来促进细胞增殖。Lin28 可以通过直接增强其翻译来促进促增殖基因的表达，从而对 HDPC 增殖进行严格控制。
