Media type: E-Article Title: Movement of stress fibers away from focal adhesions identifies focal adhesions as sites of stress fiber assembly in stationary cells Contributor: Endlich, Nicole; Otey, Carol A.; Kriz, Wilhelm; Endlich, Karlhans Published: Wiley, 2007 Published in: Cell Motility, 64 (2007) 12, Seite 966-976 Language: English DOI: 10.1002/cm.20237 ISSN: 0886-1544 Origination: Footnote: Description: AbstractForce generated in contractile actin filament bundles (stress fibers—SFs) is transmitted to the extracellular matrix (ECM) via linker proteins and transmembrane integrins at focal adhesions (FAs). Though it has long been known that actin is rapidly exchanged in FAs, the connection between SFs and FAs has not been studied in detail. We introduced fiduciary marks on SFs by expressing GFP‐palladin or GFP‐α‐actinin‐1, which are both FA and dense body proteins, and by pattern bleaching of GFP‐actin. Following fiduciary marks on SFs over time by time‐lapse fluorescence microscopy, we detected assembly of SFs at FAs in stationary cells resulting in movement of SFs away from FAs with a velocity of 0.2–0.4 μm/min. Visualization of FAs in GFP‐palladin/DsRed‐paxillin double transfected cells showed that SF elongation was not accompanied by a change in FA length. SF elongation at FAs depended on actin polymerization and force as demonstrated by inhibitors of actin polymerization (cytochalasin D, jasplakinolide) and inhibitors of myosin‐dependent contraction (blebbistatin, Y‐27632), respectively. Our finding of SF assembly at FAs has important implications for SF formation, force transmission, and tension distribution within the actin cytoskeletal network of stationary cells. Cell Motil. Cytoskeleton 2007. © 2007 Wiley‐Liss, Inc.