Force-Signaling Coupling at Single Focal Adhesions

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Castro, Nicolas S.
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Cell adhesion to extracellular matrices (ECM) is regulated by integrin receptors. After binding to ECM proteins, integrin clustering occurs to form focal adhesion (FA) complexes. These complexes contain proteins that link the cell cytoskeleton to the ECM, providing cell anchorage by mechanical transmission of adhesive forces that drive signaling, proliferation, and tissue morphogenesis. These complexes also act as signaling effectors that regulate cell division, migration, and differentiation. However, not much is known about the relationship between force generation and FA signaling, as there are many signaling proteins that interact within FAs. One of these proteins, focal adhesion kinase (FAK), is known to be a key player in the entirety of this signaling mechanism. As such, it has been postulated that FAK is also involved in force modulation at FAs. Therefore, in this thesis I analyze the relationship between FAK concentration (intensity of phosphor-FAK Y397 stained fluorescence) and force exerted at single adhesions measured with the use of microfabricated post-array-detectors (mPADs). With the information garnered from studies like these, we can build upon and continue to detail the model of cellular adhesion which we have very little information about. This research was conducted in a regenerative medicine setting, and as such, human mesenchymal stem cells (hMSCs) were used for this study. In a preliminary trial, this analysis revealed that FAK concentration is independent of forces exerted at focal adhesions after comparison between control and blebbistatin treated groups. However, in a secondary trial, a significant relationship was shown between total FAK concentration and force, as well as phosphor-FAK Y397 and force (P < 0.05). This secondary analysis suggests that FAK may be involved with force modulation.
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Undergraduate Thesis
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