Mechanics and Motility of Epithelial Cells: From Single Cell Behavior to Collective Migration

Skamrahl, Mark

dc.contributor.advisor	Janshoff, Andreas Prof. Dr.
dc.contributor.author	Skamrahl, Mark
dc.date.accessioned	2023-01-13T15:26:19Z
dc.date.available	2023-01-20T00:50:09Z
dc.date.issued	2023-01-13
dc.identifier.uri	http://resolver.sub.uni-goettingen.de/purl?ediss-11858/14458
dc.identifier.uri	http://dx.doi.org/10.53846/goediss-9668
dc.format.extent	168 Seiten	de
dc.language.iso	eng	de
dc.rights	Attribution-NonCommercial 4.0 International	*
dc.rights.uri	http://creativecommons.org/licenses/by/4.0/
dc.rights.uri	http://creativecommons.org/licenses/by-nc/4.0/	*
dc.subject.ddc	571.4	de
dc.title	Mechanics and Motility of Epithelial Cells: From Single Cell Behavior to Collective Migration	de
dc.type	cumulativeThesis	de
dc.contributor.referee	Janshoff, Andreas Prof. Dr.
dc.date.examination	2022-07-05	de
dc.description.abstracteng	Mechanical behavior of cells plays a crucial role in a plethora of biological processes. Despite its importance, this aspect of life science has only more recently gained increasing interest. Yet, without mechanical force the most basic motion cannot be initiated at any length scale, ranging from single molecules to cells, organs, and the whole organism. Similar to human motion, cells employ mechanical force to move directedly, accomplishing diverse tasks. The interplay of motility and mechanics of single cells and force transmission between tightly connected neighbor cells shapes epithelial behavior, giving rise to collective phenomena. In this dissertation, three main aspects of epithelial cell mechanics and motility are discussed. In the first project (Chapter 3), a simultaneous combination of atomic force microscopy (AFM) and fluorescence recovery after photobleaching (FRAP) was established, calibrated and then applied to cells. Here, AFM was used to provide a mechanical stimulus to single cells. In a simultaneous manner, FRAP was applied as the main readout tool, quantifying the turnover of actin in cellular stress fibers. Systematic application of forces ranging from 100 pN to 10 nN revealed a mechanical adaptation which scaled in an exponential manner: With increasing force application, actin turnover was downregulated to yield longer filaments, which could potentially withstand the external stress better. This novel combination of classic biophysical methods and its first application may enable promising insights into diverse mechanoadaptive processes, such as cell migration. Chapter 4 discusses collective migration of epithelial cell layers. Wildtype (WT) cells and ones that lack tight junction (TJ) components (ZO1/2 double knockdown, dKD) were compared. dKD cell layers were found to be immobile and jammed. This was attributed to an extreme upregulation of actomyosin contractility upon dKD. However, not all cells were able to contract: In a tug-of-war mechanism, only some cells were able to contract, thereby pulling on their neighbors, which in turn were stretched laterally. The laterally contracted cells lacked directed motion and, thus, were particularly responsible for the jamming. In contrast, the larger, stretched cells remained more mobile. This mechanism was confirmed in co-cultures of WT and dKD cells, as the contractile dKD cells slowed down the whole layer. Overall, collective migration was abolished upon TJ disruption. Interestingly, single dKD cells remained motile, rendering the described mechanism a highly collective effect. This work demonstrates that TJs are vital for collective cell migration and tissue fluidity. Building on results from Chapter 4, the third research project in Chapter 5 focused on co-cultures of dKD and WT cells. In initial migration measurements of these co-cultures a distinct demixing into clusters was observed but its origin remained unknown. Therefore, new mixing experiments were streamlined to specifically address the governing mechanism of this clustering. Here, dKD and WT cells demixed significantly compared with WT/WT controls. To explain this behavior, the tug-of-war from the previous project was examined further, this time with all dKD cells able to contract, stretching out WT neighbors. The WT cells mainly responded by excess surface area dilatation. The tug-of-war resulted in tension increase at all junctions connected to dKD cells. In addition, the dKD cells exhibited weaker cell-cell adhesion. Finally, to assess the relative impact of differential adhesion and contractility on demixing, the latter was specifically decreased. This resulted in a slowing of the initial segregation but the final demixed state remained unchanged. Accordingly, differential contractility is needed for efficient early cell segregation but adhesion dominates on longer time scales. This well-controlled case of demixing provides novel insights into how physical forces govern cell sorting, which is crucial during development.	de
dc.contributor.coReferee	Köster, Sarah Prof. Dr.
dc.contributor.thirdReferee	Großhans, Jörg Prof. Dr.
dc.contributor.thirdReferee	Rizzoli, Silvio O. Prof. Dr.
dc.contributor.thirdReferee	Bastians, Holger Prof. Dr.
dc.contributor.thirdReferee	Betz, Prof. Dr. Timo
dc.subject.eng	biophysics	de
dc.subject.eng	cell mechanics	de
dc.subject.eng	tight junctions	de
dc.subject.eng	migration	de
dc.subject.eng	cell sorting	de
dc.subject.eng	tension	de
dc.subject.eng	contractility	de
dc.subject.eng	adhesion	de
dc.subject.eng	actin	de
dc.subject.eng	atomic force microscopy	de
dc.subject.eng	jamming	de
dc.subject.eng	collective behavior	de
dc.subject.eng	epithelial cells	de
dc.subject.eng	collective migration	de
dc.subject.eng	myosin	de
dc.subject.eng	fluorescence recovery after photobleaching	de
dc.subject.eng	mechanobiology	de
dc.identifier.urn	urn:nbn:de:gbv:7-ediss-14458-0
dc.affiliation.institute	Göttinger Graduiertenschule für Neurowissenschaften, Biophysik und molekulare Biowissenschaften (GGNB)	de
dc.subject.gokfull	Biologie (PPN619462639)	de
dc.description.embargoed	2023-01-20	de
dc.identifier.ppn	1831098490
dc.identifier.orcid	https://orcid.org/0000-0002-7871-800X	de
dc.notes.confirmationsent	Confirmation sent 2023-01-13T15:45:01	de

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GGNB - Göttinger Graduiertenzentrum für Neurowissenschaften, Biophysik und molekulare Biowissenschaften [1112]
GGNB - Göttingen Graduate Center for Neurosciences, Biophysics and Molecular Biosciences

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