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  3. Stress fiber anisotropy contributes to force-mode dependent chromatin stretching and gene upregulation in living cells

Stress fiber anisotropy contributes to force-mode dependent chromatin stretching and gene upregulation in living cells

  • Nat Commun. 2020 Sep 29;11(1):4902. doi: 10.1038/s41467-020-18584-5.
Fuxiang Wei  # 1,  Xiangyu Xu  # 2,  Cunyu Zhang  # 3,  Yawen Liao  # 3,  Baohua Ji 4,  Ning Wang 5
Affiliations

Affiliations

  • 1 Laboratory for Cellular Biomechanics and Regenerative Medicine, Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074, Hubei, China. weihust@hotmail.com.
  • 2 Department of Applied Mechanics, Beijing Institute of Technology, 100081, Beijing, China.
  • 3 Laboratory for Cellular Biomechanics and Regenerative Medicine, Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074, Hubei, China.
  • 4 Biomechanics and Biomaterials Laboratory, Department of Engineering Mechanics, Zhejiang University, Hangzhou, 310027, Zhejiang, China. bhji@zju.edu.cn.
  • 5 Department of Mechanical Science and Engineering, The Grainger College of Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA. nwangrw@illinois.edu.
  • # Contributed equally.
PMID: 32994402 DOI: 10.1038/s41467-020-18584-5
Abstract

Living cells and tissues experience various complex modes of forces that are important in physiology and disease. However, how different force modes impact gene expression is elusive. Here we apply local forces of different modes via a magnetic bead bound to the integrins on a cell and quantified cell stiffness, chromatin deformation, and DHFR (dihydrofolate reductase) gene transcription. In-plane stresses result in lower cell stiffness than out-of-plane stresses that lead to bead rolling along the cell long axis (i.e., alignment of actin stress fibers) or at different angles (90° or 45°). However, chromatin stretching and ensuing DHFR gene upregulation by the in-plane mode are similar to those induced by the 45° stress mode. Disrupting stress fibers abolishes differences in cell stiffness, chromatin stretching, and DHFR gene upregulation under different force modes and inhibiting Myosin II decreases cell stiffness, chromatin deformation, and gene upregulation. Theoretical modeling using discrete anisotropic stress fibers recapitulates experimental results and reveals underlying mechanisms of force-mode dependence. Our findings suggest that forces impact biological responses of living cells such as gene transcription via previously underappreciated means.

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