CELL BIOLOGY: Stress Made Manifest

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Science  12 May 2006:
Vol. 312, Issue 5775, pp. 815d-817d
DOI: 10.1126/science.312.5775.815d

When cells attach to a surface, stress fibers (contractile actomyosin bundles) play a key role in adhesion itself and in the subsequent movements and morphology of these cells. Hotulainen and Lappalainen examined how stress fibers assemble in cultured human cells and document two pathways of formation. At the base of the cell, dorsal stress fiber assembly was driven by formin-stimulated actin assembly at focal adhesions, which are established adherent patches. In contrast, near the leading edge of the cell, unanchored ventral arcs of actin formed by means of the end-to-end assembly of bundles of the molecular motor myosin and with concomitant actin bundle assembly promoted by the Arp2/3 complex. Both dorsal stress fibers and ventral arcs were able to convert into ventral stress fibers, which are anchored to focal adhesions at the front and back of the cell. Both dorsal stress fibers and transverse arcs continually undergo assembly and disassembly; and within stress fibers, actin cross-linking remained dynamic, allowing for extensive remodeling during cell movement. — SMH

J. Cell Biol. 173, 10.1083/jcb.200511093 (2006).

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