94
views
0
recommends
+1 Recommend
0 collections
    0
    shares
      • Record: found
      • Abstract: found
      • Article: not found

      Dissociation of Cohesin from Chromosome Arms and Loss of Arm Cohesion during Early Mitosis Depends on Phosphorylation of SA2

      research-article

      Read this article at

      ScienceOpenPublisherPMC
      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          Cohesin is a protein complex that is required to hold sister chromatids together. Cleavage of the Scc1 subunit of cohesin by the protease separase releases the complex from chromosomes and thereby enables the separation of sister chromatids in anaphase. In vertebrate cells, the bulk of cohesin dissociates from chromosome arms already during prophase and prometaphase without cleavage of Scc1. Polo-like kinase 1 (Plk1) and Aurora-B are required for this dissociation process, and Plk1 can phosphorylate the cohesin subunits Scc1 and SA2 in vitro, consistent with the possibility that cohesin phosphorylation by Plk1 triggers the dissociation of cohesin from chromosome arms. However, this hypothesis has not been tested yet, and in budding yeast it has been found that phosphorylation of Scc1 by the Polo-like kinase Cdc5 enhances the cleavability of cohesin, but does not lead to separase-independent dissociation of cohesin from chromosomes. To address the functional significance of cohesin phosphorylation in human cells, we have searched for phosphorylation sites on all four subunits of cohesin by mass spectrometry. We have identified numerous mitosis-specific sites on Scc1 and SA2, mutated them, and expressed nonphosphorylatable forms of both proteins stably at physiological levels in human cells. The analysis of these cells lines, in conjunction with biochemical experiments in vitro, indicate that Scc1 phosphorylation is dispensable for cohesin dissociation from chromosomes in early mitosis but enhances the cleavability of Scc1 by separase. In contrast, our data reveal that phosphorylation of SA2 is essential for cohesin dissociation during prophase and prometaphase, but is not required for cohesin cleavage by separase. The similarity of the phenotype obtained after expression of nonphosphorylatable SA2 in human cells to that seen after the depletion of Plk1 suggests that SA2 is the critical target of Plk1 in the cohesin dissociation pathway.

          Abstract

          Cohesin holds newly replicated chromosomes together until a cell is ready to divide. These authors show how phosphorylation regulates cohesin function

          Related collections

          Most cited references50

          • Record: found
          • Abstract: found
          • Article: not found

          Cohesins: chromosomal proteins that prevent premature separation of sister chromatids.

          Cohesion between sister chromatids opposes the splitting force exerted by microtubules, and loss of this cohesion is responsible for the subsequent separation of sister chromatids during anaphase. We describe three chromosmal proteins that prevent premature separation of sister chromatids in yeast. Two, Smc1p and Smc3p, are members of the SMC family, which are putative ATPases with coiled-coil domains. A third protein, which we call Scc1p, binds to chromosomes during S phase, dissociates from them at the metaphase-to-anaphase transition, and is degraded by the anaphase promoting complex. Association of Scc1p with chromatin depends on Smc1p. Proteins homologous to Scc1p exist in a variety of eukaryotic organisms including humans. A common cohesion apparatus might be used by all eukaryotic cells during both mitosis and meiosis.
            Bookmark
            • Record: found
            • Abstract: not found
            • Article: not found

            Polo-like kinases and the orchestration of cell division.

              Bookmark
              • Record: found
              • Abstract: found
              • Article: not found

              The small molecule Hesperadin reveals a role for Aurora B in correcting kinetochore–microtubule attachment and in maintaining the spindle assembly checkpoint

              The proper segregation of sister chromatids in mitosis depends on bipolar attachment of all chromosomes to the mitotic spindle. We have identified the small molecule Hesperadin as an inhibitor of chromosome alignment and segregation. Our data imply that Hesperadin causes this phenotype by inhibiting the function of the mitotic kinase Aurora B. Mammalian cells treated with Hesperadin enter anaphase in the presence of numerous monooriented chromosomes, many of which may have both sister kinetochores attached to one spindle pole (syntelic attachment). Hesperadin also causes cells arrested by taxol or monastrol to enter anaphase within <1 h, whereas cells in nocodazole stay arrested for 3–5 h. Together, our data suggest that Aurora B is required to generate unattached kinetochores on monooriented chromosomes, which in turn could promote bipolar attachment as well as maintain checkpoint signaling.
                Bookmark

                Author and article information

                Contributors
                Role: Academic Editor
                Journal
                PLoS Biol
                pbio
                PLoS Biology
                Public Library of Science (San Francisco, USA )
                1544-9173
                1545-7885
                March 2005
                1 March 2005
                : 3
                : 3
                : e69
                Affiliations
                [1] 1Research Institute of Molecular Pathology ViennaAustria
                Stowers Institute for Medical Research United States of America
                Article
                10.1371/journal.pbio.0030069
                1054881
                15737063
                76b4be16-97fe-4d45-baf5-67f00b5dc348
                Copyright: © 2005 Hauf et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited
                History
                : 7 September 2004
                : 14 December 2004
                Categories
                Research Article
                Cell Biology
                Molecular Biology/Structural Biology
                Biochemistry
                Homo (Human)

                Life sciences
                Life sciences

                Comments

                Comment on this article