title: Actomyosin contractility spatiotemporally regulates actin network dynamics in migrating cells.
abstract: Coupling interactions among mechanical and biochemical factors are important for the realization of various cellular processes that determine cell migration. Although F-actin network dynamics has been the focus of many studies, it is not yet clear how mechanical forces generated by actomyosin contractility spatiotemporally regulate this fundamental aspect of cell migration. In this study, using a combination of fluorescent speckle microscopy and particle imaging velocimetry techniques, we perturbed the actomyosin system and examined quantitatively the consequence of actomyosin contractility on F-actin network flow and deformation in the lamellipodia of actively migrating fish keratocytes. F-actin flow fields were characterized by retrograde flow at the front and anterograde flow at the back of the lamellipodia, and the two flows merged to form a convergence zone of reduced flow intensity. Interestingly, activating or inhibiting actomyosin contractility altered network flow intensity and convergence, suggesting that network dynamics is directly regulated by actomyosin contractility. Moreover, quantitative analysis of F-actin network deformation revealed that the deformation was significantly negative and predominant in the direction of cell migration. Furthermore, perturbation experiments revealed that the deformation was a function of actomyosin contractility. Based on these results, we suggest that the actin cytoskeletal structure is a mechanically self-regulating system, and we propose an elaborate pathway for the spatiotemporal self-regulation of the actin cytoskeletal structure during cell migration. In the proposed pathway, mechanical forces generated by actomyosin interactions are considered central to the realization of the various mechanochemical processes that determine cell motility.
authors: Department of Mechanical Engineering and Science, Kyoto University, Sakyo, Kyoto, Japan.
authors: Kennedy Omondi
authors: KO
authors: Okeyo
authors: Taiji
authors: T
authors: Adachi
authors: Junko
authors: J
authors: Sunaga
authors: Masaki
authors: M
authors: Hojo
mesh_terms: D000199:Actins / Q000502:physiology*; D000205:Actomyosin / Q000502:physiology*; D000818:Animals; D002465:Cell Movement / Q000502:physiology*; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000502:physiology*; D005399:Fishes; D015603:Keratinocytes / Q000502:physiology*; D020409:Molecular Motor Proteins / Q000502:physiology*; D013314:Stress, Mechanical
chemical_list: D000199:Actins; D020409:Molecular Motor Proteins; D000205:Actomyosin