Xu Xinxin, Zhang He, Li Yuzhou, Liu Fengyi, Jing Zheng, Ren Mingxing, Chen Tao, Fu Yiru, Wu Yanqiu, Ji Ping, Yang Sheng
College of Stomatology, Chongqing Medical University, PR China.
Chongqing Key Laboratory of Oral Diseases and Biomedical Sciences, PR China.
Mater Today Bio. 2023 May 6;20:100661. doi: 10.1016/j.mtbio.2023.100661. eCollection 2023 Jun.
Matrix stiffness plays an important role in determining cell differentiation. The expression of cell differentiation-associated genes can be regulated by chromatin remodeling-mediated DNA accessibility. However, the effect of matrix stiffness on DNA accessibility and its significance for cell differentiation have not been investigated. In this study, gelatin methacryloyl (GelMA) hydrogels with different degrees of substitution were used to simulate soft, medium, and stiff matrices, and it was found that a stiff matrix promoted osteogenic differentiation of MC3T3-E1 cells by activating the Wnt pathway. In the soft matrix, the acetylation level of histones in cells was decreased, and chromatin condensed into a closed conformation, affecting the activation of β-catenin target genes (Axin2, c-Myc). Histone deacetylase inhibitor (TSA) was used to decondense chromatin. However, there was no significant increase in the expression of β-catenin target genes and the osteogenic protein Runx2. Further studies revealed that β-catenin was restricted to the cytoplasm due to the downregulation of lamin A/C in the soft matrix. Overexpression of lamin A/C and concomitant treatment of cells with TSA successfully activated β-catenin/Wnt signaling in cells in the soft matrix. The results of this innovative study revealed that matrix stiffness regulates cell osteogenic differentiation through multiple pathways, which involve complex interactions between transcription factors, epigenetic modifications of histones, and the nucleoskeleton. This trio is critical for the future design of bionic extracellular matrix biomaterials.
基质刚度在决定细胞分化中起重要作用。细胞分化相关基因的表达可由染色质重塑介导的DNA可及性调控。然而，基质刚度对DNA可及性的影响及其对细胞分化的意义尚未得到研究。在本研究中，使用具有不同取代度的甲基丙烯酰化明胶（GelMA）水凝胶来模拟软、中、硬基质，发现硬基质通过激活Wnt途径促进MC3T3-E1细胞的成骨分化。在软基质中，细胞中组蛋白的乙酰化水平降低，染色质浓缩成封闭构象，影响β-连环蛋白靶基因（Axin2、c-Myc）的激活。使用组蛋白去乙酰化酶抑制剂（TSA）使染色质解聚。然而，β-连环蛋白靶基因和成骨蛋白Runx2的表达没有显著增加。进一步研究表明，由于软基质中层粘连蛋白A/C的下调，β-连环蛋白被限制在细胞质中。层粘连蛋白A/C的过表达以及细胞与TSA的联合处理成功激活了软基质中细胞的β-连环蛋白/Wnt信号。这项创新性研究的结果表明，基质刚度通过多种途径调节细胞成骨分化，这些途径涉及转录因子之间的复杂相互作用、组蛋白的表观遗传修饰和核骨架。这三者对于未来仿生细胞外基质生物材料的设计至关重要。
