Department of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, Georgia 30322, United States.
Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, 313 Ferst Drive, Atlanta, Georgia 30332, United States.
ACS Nano. 2022 Apr 26;16(4):5335-5348. doi: 10.1021/acsnano.1c04303. Epub 2022 Mar 24.
Cardiac muscle cells (CMCs) are the unit cells that comprise the heart. CMCs go through different stages of differentiation and maturation pathways to fully mature into beating cells. These cells can sense and respond to mechanical cues through receptors such as integrins which influence maturation pathways. For example, cell traction forces are important for the differentiation and development of functional CMCs, as CMCs cultured on varying substrate stiffness function differently. Most work in this area has focused on understanding the role of bulk extracellular matrix stiffness in mediating the functional fate of CMCs. Given that stiffness sensing mechanisms are mediated by individual integrin receptors, an important question in this area pertains to the specific magnitude of integrin piconewton (pN) forces that can trigger CMC functional maturation. To address this knowledge gap, we used DNA adhesion tethers that rupture at specific thresholds of force (∼12, ∼56, and ∼160 pN) to test whether capping peak integrin tension to specific magnitudes affects CMC function. We show that adhesion tethers with greater force tolerance lead to functionally mature CMCs as determined by morphology, twitching frequency, transient calcium flux measurements, and protein expression (F-actin, vinculin, α-actinin, YAP, and SERCA2a). Additionally, sarcomeric actinin alignment and multinucleation were significantly enhanced as the mechanical tolerance of integrin tethers was increased. Taken together, the results show that CMCs harness defined pN integrin forces to influence early stage development. This study represents an important step toward biophysical characterization of the contribution of pN forces in early stage cardiac differentiation.
心肌细胞(CMCs)是构成心脏的单元细胞。CMCs 经历不同的分化和成熟途径,以完全成熟为跳动细胞。这些细胞可以通过整合素等受体感知和响应机械线索,这些受体影响成熟途径。例如,细胞牵引力对于功能性 CMC 的分化和发育很重要,因为在不同基质硬度上培养的 CMC 功能不同。该领域的大多数工作都集中在理解细胞外基质整体刚度在介导 CMC 功能命运中的作用。鉴于刚度感应机制是由单个整合素受体介导的,该领域的一个重要问题涉及可以触发 CMC 功能成熟的特定整合素皮牛顿(pN)力的幅度。为了解决这一知识差距,我们使用 DNA 粘附系链,这些系链在特定的力阈值(约 12、约 56 和约 160 pN)处断裂,以测试将峰值整合素张力固定在特定幅度是否会影响 CMC 功能。我们表明,具有更大力容限的粘附系链会导致 CMC 功能成熟,这可以通过形态、抽搐频率、瞬时钙通量测量和蛋白质表达(F-肌动蛋白、桩蛋白、α-辅肌动蛋白、YAP 和 SERCA2a)来确定。此外,随着整合素系链机械容限的增加,肌节肌动蛋白排列和多核化显著增强。总之,这些结果表明 CMC 利用特定的 pN 整合素力来影响早期发育。这项研究代表了向早期心脏分化中 pN 力贡献的生物物理特征描述迈出的重要一步。