Nuclear size changes caused by local motion of cell boundaries unfold the nuclear lamina and dilate chromatin and intranuclear bodies

Katiyar, Aditya; Tocco, Vincent J.; Li, Yuan; Aggarwal, Varun; Tamashunas, Andrew C; Dickinson, Richard B.; Lele, Tanmay P.

doi:10.1039/c9sm01666j

Cited by 25 publications

(22 citation statements)

References 49 publications

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“…Increases in the volume of nuclei either through swelling ( Finan et al. , 2011 ) or directed migration on patterned substrates ( Katiyar et al. , 2019 ) has been shown to decondense or dilate chromatin levels.…”

Section: Introductionmentioning

confidence: 99%

Correlating nuclear morphology and external force with combined atomic force microscopy and light sheet imaging separates roles of chromatin and lamin A/C in nuclear mechanics

Hobson

Kern

O’Brien

et al. 2020

MBoC

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Section: Introductionmentioning

confidence: 99%

Correlating nuclear morphology and external force with combined atomic force microscopy and light sheet imaging separates roles of chromatin and lamin A/C in nuclear mechanics

Hobson

Kern

O’Brien

et al. 2020

MBoC

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“…We next set out to inhibit actomyosin contractility in PdLFs and examined the effect of such modulation on mRNA levels of a few chosen genes. MLC phosphorylation is regulated by two different enzymes—Rho‐associated kinase (ROCK) which is an effector of Rho GTPase, and myosin light chain kinase (MLCK) whose activation mechanism involves a calcium dependent calmodulin pathway (Katoh et al, 2001; Ridley & Hall, 1992, 1994; Tanner et al, 2010). We sought to inhibit myosin activity by using three different inhibitors: ML‐7 which is an inhibitor of MLCK, Y27632 which is an inhibitor of ROCK, and blebbistatin, a specific myosin ATPase inhibitor.…”

Section: Resultsmentioning

confidence: 99%

Osteoprotegerin is sensitive to actomyosin tension in human periodontal ligament fibroblasts

Tamashunas

Katiyar

Zhang

et al. 2021

Journal Cellular Physiology

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Periodontal ligament fibroblasts (PdLFs) are an elongated cell type in the periodontium with matrix and bone regulatory functions which become abnormal in periodontal disease (PD). Here we found that the normally elongated and oriented PdLF nucleus becomes rounded and loses orientation in a mouse model of PD. Using in vitro micropatterning of cultured primary PdLF cell shape, we show that PdLF elongation correlates with nuclear elongation and the presence of thicker, contractile F‐actin fibers. The rounded nuclei in mouse PD models in vivo are, therefore, indicative of reduced actomyosin tension. Inhibiting actomyosin contractility by inhibiting myosin light chain kinase, Rho kinase or myosin ATPase activity, in cultured PdLFs each consistently reduced messenger RNA levels of bone regulatory protein osteoprotegerin (OPG). Infection of cultured PdLFs with two different types of periodontal bacteria (Porphyromonas gingivalis and Fusobacterium nucleatum) failed to recapitulate the observed nuclear rounding in vivo, upregulated nonmuscle myosin II phosphorylation and downregulated OPG. Collectively, our results add support to the hypothesis that PdLF contractility becomes decreased and contributes to disease progression in PD.

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“…Quantitative measurements of cell and nuclear heights have been performed from x – z cross‐sections reconstructed from confocal microscopy of x – y planes captured at different z‐positions 6,9,11–24 . Such measurements have allowed mechanistic studies of cell spreading and nuclear flattening.…”

Section: Discussionmentioning

confidence: 99%

A method for direct imaging of x–z cross‐sections of fluorescent samples

Katiyar

Antani

Mckee

et al. 2020

Journal of Microscopy

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Summary The x–z cross‐sectional profiles of fluorescent objects can be distorted in confocal microscopy, in large part due to mismatch between the refractive index of the immersion medium of typical high numerical aperture objectives and the refractive index of the medium in which the sample is present. Here, we introduce a method to mount fluorescent samples parallel to the optical axis. This mounting allows direct imaging of what would normally be an x–z cross‐section of the object, in the x–y plane of the microscope. With this approach, the x–y cross‐sections of fluorescent beads were seen to have significantly lower shape‐distortions as compared to x–z cross‐sections reconstructed from confocal z‐stacks. We further tested the method for imaging of nuclear and cellular heights in cultured cells, and found that they are significantly flatter than previously reported. This approach allows improved imaging of the x–z cross‐section of fluorescent samples. Lay description Optical distortions are common in confocal microscopy. In particular, the mismatch between the refractive index of the immersion medium of the microscope objective and the refractive index of the sample medium distorts the shapes of fluorescent objects in the x–z plane of the microscope. Here, we introduced a method to eliminate the shape‐distortion in the x–z cross‐sections. This was achieved by mounting fluorescent samples on vertical glass slides such that the cross‐sections orthogonal to the glass surface could be imaged in the x–y plane of the microscope. Our method successfully improved the imaging of nuclear and cellular heights in cultured cells and revealed that the heights were significantly flatter than previously reported with conventional approaches.

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Nuclear size changes caused by local motion of cell boundaries unfold the nuclear lamina and dilate chromatin and intranuclear bodies

Abstract: Nuclear size changes caused by motion of cell boundaries during cell migration alters intranuclear structures.

Cited by 25 publications

References 49 publications

Correlating nuclear morphology and external force with combined atomic force microscopy and light sheet imaging separates roles of chromatin and lamin A/C in nuclear mechanics

Correlating nuclear morphology and external force with combined atomic force microscopy and light sheet imaging separates roles of chromatin and lamin A/C in nuclear mechanics

Osteoprotegerin is sensitive to actomyosin tension in human periodontal ligament fibroblasts

A method for direct imaging of x–z cross‐sections of fluorescent samples

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