Mapping stress inside living cells by atomic force microscopy in response to environmental stimuli
Creators: name: Wang, Hongxin
name: Zhang, Han
name: Tamura, Ryo
name: Da, Bo
name: Abdellatef, Shimaa A.
name: Watanabe, Ikumu
name: Ishida, Nobuyuki
name: Fujita, Daisuke
name: Hanagata, Nobutaka
name: Nakagawa, Tomoki
name: Nakanishi, Jun
Publisher: name: Taylor & Francis
Year: 2023
Subjects: subject: Biophysics
subject: Physical Sciences not elsewhere classified
subject: Cell Biology
subject: Physiology
subject: FOS: Biological sciences
subject: Biotechnology
subject: Biological Sciences not elsewhere classified
subject: Computational Biology

description: The response of cells to environmental stimuli, under either physiological or pathological conditions, plays a key role in determining cell fate toward either adaptive survival or controlled death. The efficiency of such a feedback mechanism is closely related to the most challenging human diseases, including cancer. Since cellular responses are implemented through physical forces exerted on intracellular components, more detailed knowledge of force distribution through modern imaging techniques is needed to ensure a mechanistic understanding of these forces. In this work, we mapped these intracellular forces at a whole-cell scale and with submicron resolution to correlate intracellular force distribution to the cytoskeletal structures. Furthermore, we visualized dynamic mechanical responses of the cells adapting to environmental modulations in situ. Such task was achieved by using an informatics-assisted atomic force microscope (AFM) indentation technique where a key step was Markov-chain Monte Carlo optimization to search for both the models used to fit indentation force–displacement curves and probe geometry descriptors. We demonstrated force dynamics within cytoskeleton, as well as nucleoskeleton in living cells which were subjected to mechanical state modulation: myosin motor inhibition, micro-compression stimulation and geometrical confinement manipulation. Our results highlight the alteration in the intracellular prestress to attenuate environmental stimuli; to involve in cellular survival against mechanical signal-initiated death during cancer growth and metastasis; and to initiate cell migration. Quantitative knowledge of internal force distribution in living cells is crucial to understand how cellular machinery responds mechanically to changes in the extracellular environment. Conventional force-sensing methods, which rely on pre-attached sensors, are incapable of providing whole-cell information with high spatial resolution. By machine learning assistance, we could improve AFM indentation’s force sensitivity to a level that now enabled force (prestress) to be mapped on whole living cells with submicron resolution. The new capability revealed that cells actively redistribute forces among intracellular components to mitigate negative influence from the environment, and such response mechanisms could be used to understand ailing cellular states like cancer. Watch the video on Vimeo © 2023 The Author(s). Published by National Institute for Materials Science in partnership with Taylor &amp; Francis Group.