Biology subjects

Ruebeling, A.

Publications and source records attributed to Ruebeling, A..

3 recordsLinked to original sources

bioRxiv2024

Active fluctuations of cells reduce friction to enable fast and coherent collective migration

Collective cell migration is an emergent phenomenon, with long-range cell-cell communication influenced by various factors, including transmission of forces, viscoelasticity of individual cells, substrate interactions, and mechanotransduction. We investigate how alterations in cell-substrate distance fluctuations, cell-substrate adhesion, and traction forces impact the average velocity and temporal-spatial correlation of confluent monolayers formed either by wild-type MDCKII cells or zonula occludens (ZO) 1/2-depleted MDCKII cells (dKD) representing highly contractile cells. The data indicates that confluent dKD monolayers exhibit decreased average velocity compared to less contractile WT cells concomitant with increased substrate adhesion, reduced traction forces, a more compact shape, diminished cell-cell interactions, and reduced cell-substrate distance fluctuations. Depletion of basal actin and myosin further supports the notion that short-range cell-substrate interactions, particularly fluctuations driven by basal actomyosin, significantly influence the migration speed of the monolayer on a larger length scale.

biophysics↗

bioRxiv2022

Cellular segregation in co-cultures driven by differential adhesion and contractility on distinct time scales

Cellular sorting and pattern formation are crucial for many biological processes such as development, tissue regeneration, and cancer progression. Prominent physical driving forces for cellular sorting are differential adhesion and contractility. Here, we studied the segregation of epithelial co-cultures containing highly contractile, ZO1/2-depleted MDCKII cells (dKD) and their wildtype (WT) counterparts using multiple quantitative, high-throughput methods to monitor their dynamical and mechanical properties. We observe a time-dependent segregation process, governed mainly by differential contractility on short (< 5 h) and differential adhesion on long (> 5 h) time scales, respectively. The overly contractile dKD cells exert strong lateral forces on their WT neighbors, thereby apically depleting their surface area. This is reflected in a six-fold difference in excess surface area between both cell types. The lateral forces lead to a four-to sixfold increase in tension at all junctions that are in contact with the contractile cells including the interface between heterotypic cell-cell contacts. Concomitantly, the tight junction-depleted, contractile cells exhibit weaker cell-cell adhesion and lower traction force. Drug-induced contractility reduction and partial calcium depletion delay the initial segregation but cease to change the final demixed state, rendering differential adhesion the dominant segregation force at longer time scales. This well-controlled model system shows how cell sorting is accomplished through a complex interplay between differential adhesion and contractility and can be explained largely by generic physical driving forces. Significance StatementFundamental biological processes, such as tissue morphogenesis during development, rely on the correct sorting of cells. Cellular sorting is governed by basic physical properties such as the adhesion between cells and their individual contractility. Here, we study the impact of these parameters in co-cultures consisting of epithelial wildtype cells and overly contractile, less adhesive tight junction-depleted ones. We find time-dependent segregation into clusters: differential contractility drives fast segregation on short-time scales, while differential adhesion dominates the final segregated state over longer times.

biophysics↗

bioRxiv2021

Tight junction ZO proteins maintain tissue fluidity, ensuring efficient collective cell migration

Tight junctions are essential components of epithelial tissues connecting neighboring cells to provide protective barriers. Albeit their general function to seal compartments is well understood, their role in collective cell migration is largely unexplored. Here, the importance of the tight junction proteins ZO1 and ZO2 for epithelial migration is investigated employing video microscopy in conjunction with velocimetry, segmentation, cell tracking, and atomic force microscopy/spectroscopy. The results indicate that ZO proteins are necessary for fast and coherent migration. In particular, ZO1 and 2 loss (dKD) induces actomyosin remodeling away from the central cortex towards the periphery of individual cells, resulting in altered viscoelastic properties. A tug-of-war emerges between two subpopulations of cells with distinct morphological and mechanical properties: 1) smaller and highly contractile cells with an outward-bulged apical membrane, and 2) larger, flattened cells, which, due to tensile stress, display a higher proliferation rate. In response, the cell density increases, leading to crowding-induced jamming and more small cells over time. Co-cultures comprising wildtype and dKD cells display phase separation based on differences in contractility rather than differential adhesion. This study shows that ZO proteins are necessary for efficient collective cell migration by maintaining tissue fluidity and controlling proliferation.

biophysics↗