title: Non-monotonic cellular responses to heterogeneity in talin protein expression-level.
abstract: Talin is a key cell-matrix adhesion component with a central role in regulating adhesion complex maturation, and thereby various cellular properties including adhesion and migration. However, knockdown studies have produced inconsistent findings regarding the functional influence of talin in these processes. Such discrepancies may reflect non-monotonic responses to talin expression-level variation that are not detectable via canonical "binary" comparisons of aggregated control versus knockdown cell populations. Here, we deployed an "analogue" approach to map talin influence across a continuous expression-level spectrum, which we extended with sub-maximal RNAi-mediated talin depletion. Applying correlative imaging to link live cell and fixed immunofluorescence data on a single cell basis, we related per cell talin levels to per cell measures quantitatively defining an array of cellular properties. This revealed both linear and non-linear correspondences between talin expression and cellular properties, including non-monotonic influences over cell shape, adhesion complex-F-actin association and adhesion localization. Furthermore, we demonstrate talin level-dependent changes in networks of correlations among adhesion/migration properties, particularly in relation to cell migration speed. Importantly, these correlation networks were strongly affected by talin expression heterogeneity within the natural range, implying that this endogenous variation has a broad, quantitatively detectable influence. Overall, we present an accessible analogue method that reveals complex dependencies on talin expression-level, thereby establishing a framework for considering non-linear and non-monotonic effects of protein expression-level heterogeneity in cellular systems.
authors.affiliation: Center for Innovative Medicine, Department of Biosciences and Nutrition, Karolinska Institutet, Novum, Hälsov. 7-9, G-building floor 6, S-141 83 Huddinge, Sweden. staffan.stromblad@ki.se john.lock@ki.se.
authors.forename: Alexa
authors.initials: A
authors.lastname: Kiss
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Gong
authors.forename: Jacob M
authors.initials: JM
authors.lastname: Kowalewski
authors.forename: Hamdah
authors.initials: H
authors.lastname: Shafqat-Abbasi
authors.forename: Staffan
authors.initials: S
authors.lastname: Strömblad
authors.forename: John G
authors.initials: JG
authors.lastname: Lock
mesh_terms: D001696:Biomechanical Phenomena; D002448:Cell Adhesion / Q000502:physiology; D002460:Cell Line; D002465:Cell Movement / Q000502:physiology; D015870:Gene Expression; D055785:Gene Knockdown Techniques; D006801:Humans; D018613:Microscopy, Confocal; D008954:Models, Biological; D017711:Nonlinear Dynamics; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D059010:Single-Cell Analysis; D049490:Systems Biology; D016608:Talin / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*
chemical_list: D034741:RNA, Small Interfering; C518832:TLN1 protein, human; D016608:Talin