Deformation Microscopy for Dynamic Intracellular and Intranuclear Mapping of Mechanics with High Spatiotemporal Resolution

Ghosh, Soham; Seelbinder, Benjamin; Henderson, Jonathan T.; Watts, Ryan D.; Scott, Adrienne K.; Veress, Alexander I.; Neu, Corey P.

doi:10.1016/j.celrep.2019.04.009

Cited by 56 publications

(62 citation statements)

References 59 publications

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“…Recently, an emerging technique—deformation microscopy—has revealed high‐resolution strain maps of cells under deformation in vitro and in vivo, thus providing mechanistic insight into nuclear mechanics with compromised intracellular components, such as lamin A/C and the linker of nucleoskeleton and cytoskeleton complexes. [ 12,13 ] However, because the distribution of deforming loads within a cell is unknown, discriminating the intrinsic role of the nuclear modulus remains difficult.…”

Section: Introductionmentioning

confidence: 99%

Nuclear Mechanics within Intact Cells Is Regulated by Cytoskeletal Network and Internal Nanostructures

Zhang

Alisafaei

Nikolić

et al. 2020

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The mechanical properties of the cellular nucleus are extensively studied as they play a critical role in important processes, such as cell migration, gene transcription, and stem cell differentiation. While the mechanical properties of the isolated nucleus have been tested, there is a lack of measurements about the mechanical behavior of the nucleus within intact cells and specifically about the interplay of internal nuclear components with the intracellular microenvironment, because current testing methods are based on contact and only allow studying the nucleus after isolation from a cell or disruption of cytoskeleton. Here, all‐optical Brillouin microscopy and 3D chemomechanical modeling are used to investigate the regulation of nuclear mechanics in physiological conditions. It is observed that the nuclear modulus can be modulated by epigenetic regulation targeting internal nuclear nanostructures such as lamin A/C and chromatin. It is also found that nuclear modulus is strongly regulated by cytoskeletal behavior through a robust mechanism conserved in different culturing conditions. Given the active role of cytoskeletal modulation in nearly all cell functions, this work will enable to reveal highly relevant mechanisms of nuclear mechanical regulations in physiological and pathological conditions.

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Section: Introductionmentioning

confidence: 99%

Nuclear Mechanics within Intact Cells Is Regulated by Cytoskeletal Network and Internal Nanostructures

Zhang

Alisafaei

Nikolić

et al. 2020

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“…First, the displacement map is obtained through deformation microscopy. [ 24 ] It is to be noted that the displacement fields are computed for thousands of nodes [ 24 ] and all of them are subsequently used for elastography. For visualization purpose, the displacement fields are shown for a few nodes only.…”

Section: Resultsmentioning

confidence: 99%

“…In the present study, we establish, validate, and demonstrate the application of “nuclear elastography,” a technique to quantify the elasticity of the heterochromatin and the euchromatin domains of a deforming nucleus through an elaborate microscopic image analysis‐based workflow. To accomplish this multistep process, we first quantified the displacement map in the nucleus using our previously established technique “deformation microscopy.” [ 24 ] Next, we executed an inverse problem solution framework to iteratively calculate the elasticity of the chromatin domains by using the already computed intranuclear displacement field, and the boundary displacement information as the boundary condition. As the model system, we applied the technique on the nucleus of murine embryonic cardiomyocytes cultured on a polydimethylsiloxane (PDMS) substrate thus exploiting the inherent deformation behavior of beating cardiomyocytes in vitro.…”

Section: Introductionmentioning

confidence: 99%

Image‐Based Elastography of Heterochromatin and Euchromatin Domains in the Deforming Cell Nucleus

Ghosh

Cuevas

Seelbinder

et al. 2021

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Chromatin of the eukaryotic cell nucleus comprises microscopically dense heterochromatin and loose euchromatin domains, each with distinct transcriptional ability and roles in cellular mechanotransduction. While recent methods are developed to characterize the mechanics of nucleus, measurement of intranuclear mechanics remains largely unknown. Here, the development of “nuclear elastography,” which combines microscopic imaging and computational modeling to quantify the relative elasticity of the heterochromatin and euchromatin domains, is described. Using contracting murine embryonic cardiomyocytes, nuclear elastography reveals that the heterochromatin is almost four times stiffer than the euchromatin at peak deformation. The relative elasticity between the two domains changes rapidly during the active deformation of the cardiomyocyte in the normal physiological condition but progresses more slowly in cells cultured in a mechanically stiff environment, although the relative stiffness at peak deformation does not change. Further, it is found that the disruption of the Klarsicht, ANC‐1, Syne Homology domain of the Linker of Nucleoskeleton and Cytoskeleton complex compromises the intranuclear elasticity distribution resulting in elastically similar heterochromatin and euchromatin. These results provide insight into the elastography dynamics of heterochromatin and euchromatin domains and provide a noninvasive framework to further investigate the mechanobiological function of subcellular and subnuclear domains limited only by the spatiotemporal resolution of the acquired images.

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“…Quantifying the bulk mechanical properties of the nucleus can be performed via atomic force microscopes, micropipette setups, optical tweezers, or microfluidics 11 . While single-cell level optical methods to measure intra-nuclear deformations are emerging 12 , cellular FE models that can capture nuclear structure and predict nuclear mechanics of many nuclei could provide mechanistic information on cell’s mechanical properties and at the same time, present a time-saving and cost-effective alternative. The stiffness of the nucleus is primarily affected by two nuclear components, LaminA/C and chromatin 13 .…”

Section: Introductionmentioning

confidence: 99%

Modeling stem cell nucleus mechanics using confocal microscopy

Kennedy

Newberg

Goelzer

et al. 2020

Preprint

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Nuclear mechanics is emerging as a key component of stem cell function and differentiation. While changes in nuclear structure can be visually imaged with confocal microscopy, mechanical characterization of the nucleus and its sub-cellular components require specialized testing equipment. A computational model permitting cell-specific mechanical information directly from confocal and atomic force microscopy of cell nuclei would be of great value. Here, we developed a computational framework for generating finite element models of isolated cell nuclei from multiple confocal microscopy scans and simple atomic force microscopy (AFM) tests. Confocal imaging stacks of isolated mesenchymal stem cells (MSC) were converted into finite element models and siRNA-mediated LaminA/C depletion isolated chromatin and LaminA/C structures. Using AFM-measured experimental stiffness values, a set of conversion factors were determined for both chromatin and LaminA/C to map the voxel intensity of the original images to the element stiffness, allowing the prediction of nuclear stiffness in an additional set of other nuclei. The developed computational framework will identify the contribution of a multitude of sub-nuclear structures and predict global nuclear stiffness of multiple nuclei based on simple nuclear isolation protocols, confocal images and AFM tests.

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Deformation Microscopy for Dynamic Intracellular and Intranuclear Mapping of Mechanics with High Spatiotemporal Resolution

Cited by 56 publications

References 59 publications

Nuclear Mechanics within Intact Cells Is Regulated by Cytoskeletal Network and Internal Nanostructures

Nuclear Mechanics within Intact Cells Is Regulated by Cytoskeletal Network and Internal Nanostructures

Image‐Based Elastography of Heterochromatin and Euchromatin Domains in the Deforming Cell Nucleus

Modeling stem cell nucleus mechanics using confocal microscopy

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