Determining mechanical features of modulated epithelial monolayers using subnuclear particle tracking

Abstract

Force generation within cells, mediated by motor proteins along cytoskeletal networks, maintains the function of multicellular structures during homeostasis and when generating collective forces. Here, we describe the use of chromatin dynamics to detect cellular force propagation [a technique termed SINK (sensors from intranuclear kinetics)] and investigate the force response of cells to disruption of the monolayer and changes in substrate stiffness. We find that chromatin dynamics change in a substrate stiffness-dependent manner within epithelial monolayers. We also investigate point defects within monolayers to map the impact on the strain field of a heterogeneous monolayer. We find that cell monolayers behave as a colloidal assembly rather than as a continuum since the data fit an exponential decay; the lateral characteristic length of recovery from the mechanical defect is ∼50 µm for cells with a 10 µm spacing. At distances greater than this characteristic length, cells behave similarly to those in a fully intact monolayer. This work demonstrates the power of SINK to investigate diseases including cancer and atherosclerosis that result from single cells or heterogeneities in monolayers.This article has an associated First Person interview with the first author of the paper.

Mechanical Stabilization of the Glandular Acinus by Linker of Nucleoskeleton and Cytoskeleton Complex

“…Establishing and sustaining such an unstable mechanical equilibrium would require a control mechanism (which requires further investigation) to regulate T and/or P in response to actomyosin fluctuations. Disruption of the LINC complex can alter cell mechanotransduction [62,63], mechanosensitive gene expression [10], nuclear body dynamics [64,65], cell migration [66], nuclear positioning [5,17,[67][68][69][70], the assembly of the actomyosin cytoskeleton [5,[71][72][73], and the mechanical properties of the nucleus [39]. Our results add to this literature by showing that mechanical continuity between the nucleus and the cytoskeleton is required for maintaining three-dimensional tissue architecture and mechanics.…”

Cytoplasmic volume and limiting nucleoplasmin scale nuclear size duringXenopus laevisdevelopment

“…Another model is that Npm2 induces nuclear growth by altering chromatin topology or higher order structure. Npm2 might affect nucleosome assembly, chromatin-association of linker histones and chromatin binding/remodeling proteins, and/or connections between chromatin and the NE (Armiger et al, 2018;Bartholomew, 2014;Chalut et al, 2012;Guelen et al, 2008;Harr et al, 2016;Kruithof et al, 2009;Li and Reinberg, 2011;Luperchio et al, 2014;Macadangdang et al, 2014;Maeshima et al, 2016;Pajerowski et al, 2007;Roopa and Shivashankar, 2006;Schreiner et al, 2015;Shimamoto et al, 2017;Spagnol et al, 2016;Spagnol and Dahl, 2014;Stephens et al, 2017;Stephens et al, 2018;Szerlong and Hansen, 2011;Zidovska et al, 2013).…”

Imaging methods in mechanosensing: a historical perspective and visions for the future

“…For example, reduced myosin motor activity on the actin cytoskeleton can be seen in a decrease in the MSDs of fluorescent tracers in the nucleus ( Spagnol and Dahl, 2014 ). Subsequent studies have been able to demonstrate for the first time that changes to the external environment of the cell, such as substrate compliance or cell confluence, can actively affect movement of the nuclear interior ( Armiger et al. , 2018 ).…”