title: YAP Nuclear Localization in the Absence of Cell-Cell Contact Is Mediated by a Filamentous Actin-dependent, Myosin II- and Phospho-YAP-independent Pathway during Extracellular Matrix Mechanosensing.
abstract: Cell-cell contact inhibition and the mechanical environment of cells have both been shown to regulate YAP nuclear localization to modulate cell proliferation. Changes in cellular contractility by genetic, pharmacological, and matrix stiffness perturbations regulate YAP nuclear localization. However, because contractility and F-actin organization are interconnected cytoskeletal properties, it remains unclear which of these distinctly regulates YAP localization. Here we show that in the absence of cell-cell contact, actomyosin contractility suppresses YAP phosphorylation at Ser(112), however, neither loss of contractility nor increase in YAP phosphorylation is sufficient for its nuclear exclusion. We find that actin cytoskeletal integrity is essential for YAP nuclear localization, and can override phosphoregulation or contractility-mediated regulation of YAP nuclear localization. This actin-mediated regulation is conserved during mechanotransduction, as substrate compliance increased YAP phosphorylation and reduced cytoskeletal integrity leading to nuclear exclusion of both YAP and Ser(P)(112)-YAP. These data provide evidence for two actin-mediated pathways for YAP regulation; one in which actomyosin contractility regulates YAP phosphorylation, and a second that involves cytoskeletal integrity-mediated regulation of YAP nuclear localization independent of contractility. We suggest that in non-contact inhibited cells, this latter mechanism may be important in low stiffness regimes, such as may be encountered in physiological environments.
authors.affiliation: From the Cell Biology and Physiology Center, NHLBI, National Institutes of Health, Bethesda, Maryland 20892 and the Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
authors.forename: Arupratan
authors.initials: A
authors.lastname: Das
authors.affiliation: From the Cell Biology and Physiology Center, NHLBI, National Institutes of Health, Bethesda, Maryland 20892 and.
authors.forename: Robert S
authors.initials: RS
authors.lastname: Fischer
authors.affiliation: the Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
authors.forename: Duojia
authors.initials: D
authors.lastname: Pan
authors.affiliation: From the Cell Biology and Physiology Center, NHLBI, National Institutes of Health, Bethesda, Maryland 20892 and watermancm@nhlbi.nih.gov.
authors.forename: Clare M
authors.initials: CM
authors.lastname: Waterman
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism; D021581:Active Transport, Cell Nucleus; D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D000818:Animals; D002448:Cell Adhesion; D018797:Cell Cycle Proteins; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism*; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000502:physiology; D005109:Extracellular Matrix; D006801:Humans; D040542:Mechanotransduction, Cellular; D051379:Mice; D024462:Myosin Type II / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D000091102:YAP-Signaling Proteins
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D018797:Cell Cycle Proteins; D010750:Phosphoproteins; D000091102:YAP-Signaling Proteins; C486223:Yap1 protein, mouse; D024462:Myosin Type II
keywords: F-actin; Hippo pathway; YAP; cell adhesion; contact inhibition; contractility; cytoskeleton; mechanotransduction; myosin