Publications by authors named "Mary Kate Bonner"

7 Publications

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The Borealin dimerization domain interacts with Sgo1 to drive Aurora B-mediated spindle assembly.

Mol Biol Cell 2020 09 22;31(20):2207-2218. Epub 2020 Jul 22.

Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, NIH, Bethesda, MD 20892.

The chromosomal passenger complex (CPC), which includes the kinase Aurora B, is a master regulator of meiotic and mitotic processes that ensure the equal segregation of chromosomes. Sgo1 is thought to play a major role in the recruitment of the CPC to chromosomes, but the molecular mechanism and contribution of Sgo1-dependent CPC recruitment is currently unclear. Using egg extracts and biochemical reconstitution, we found that Sgo1 interacts directly with the dimerization domain of the CPC subunit Borealin. Borealin and the PP2A phosphatase complex can bind simultaneously to the coiled-coil domain of Sgo1, suggesting that Sgo1 can integrate Aurora B and PP2A activities to modulate Aurora B substrate phosphorylation. A Borealin mutant that specifically disrupts the Sgo1-Borealin interaction results in defects in CPC chromosomal recruitment and Aurora B-dependent spindle assembly, but not in spindle assembly checkpoint signaling at unattached kinetochores. These findings establish a direct molecular connection between Sgo1 and the CPC and have major implications for the different functions of Aurora B, which promote the proper interaction between spindle microtubules and chromosomes.
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http://dx.doi.org/10.1091/mbc.E20-05-0341DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7550704PMC
September 2020

Enrichment of Aurora B kinase at the inner kinetochore controls outer kinetochore assembly.

J Cell Biol 2019 10 16;218(10):3237-3257. Epub 2019 Sep 16.

Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD

Outer kinetochore assembly enables chromosome attachment to microtubules and spindle assembly checkpoint (SAC) signaling in mitosis. Aurora B kinase controls kinetochore assembly by phosphorylating the Mis12 complex (Mis12C) subunit Dsn1. Current models propose Dsn1 phosphorylation relieves autoinhibition, allowing Mis12C binding to inner kinetochore component CENP-C. Using egg extracts and biochemical reconstitution, we found that autoinhibition of the Mis12C by Dsn1 impedes its phosphorylation by Aurora B. Our data indicate that the INCENP central region increases Dsn1 phosphorylation by enriching Aurora B at inner kinetochores, close to CENP-C. Furthermore, centromere-bound CENP-C does not exchange in mitosis, and CENP-C binding to the Mis12C dramatically increases Dsn1 phosphorylation by Aurora B. We propose that the coincidence of Aurora B and CENP-C at inner kinetochores ensures the fidelity of kinetochore assembly. We also found that the central region is required for the SAC beyond its role in kinetochore assembly, suggesting that kinetochore enrichment of Aurora B promotes the phosphorylation of other kinetochore substrates.
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http://dx.doi.org/10.1083/jcb.201901004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6781445PMC
October 2019

Distinct Roles of the Chromosomal Passenger Complex in the Detection of and Response to Errors in Kinetochore-Microtubule Attachment.

Dev Cell 2017 09;42(6):640-654.e5

Laboratory of Biochemistry & Molecular Biology, National Cancer Institute, NIH, Bethesda, MD 20892, USA. Electronic address:

The chromosomal passenger complex (CPC) localizes to centromeres in early mitosis to activate its subunit Aurora B kinase. However, it is unclear whether centromeric CPC localization contributes to CPC functions beyond Aurora B activation. Here, we show that an activated CPC that cannot localize to centromeres supports functional assembly of the outer kinetochore but is unable to correct errors in kinetochore-microtubule attachment in Xenopus egg extracts. We find that CPC has two distinct roles at centromeres: one to selectively phosphorylate Ndc80 to regulate attachment and a second, conserved kinase-independent role in the proper composition of inner kinetochore proteins. Although a fully assembled inner kinetochore is not required for outer kinetochore assembly, we find it is essential to recruit tension indicators, such as BubR1 and 3F3/2, to erroneous attachments. We conclude centromeric CPC is necessary for tension-dependent removal of erroneous attachments and for the kinetochore composition required to detect tension loss.
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http://dx.doi.org/10.1016/j.devcel.2017.08.022DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6260983PMC
September 2017

Profiling of the mammalian mitotic spindle proteome reveals an ER protein, OSTD-1, as being necessary for cell division and ER morphology.

PLoS One 2013 10;8(10):e77051. Epub 2013 Oct 10.

Laboratory of Genetics and Medical Genetics, University of Wisconsin-Madison, Madison, Wisconsin, United States of America.

Cell division is important for many cellular processes including cell growth, reproduction, wound healing and stem cell renewal. Failures in cell division can often lead to tumors and birth defects. To identify factors necessary for this process, we implemented a comparative profiling strategy of the published mitotic spindle proteome from our laboratory. Of the candidate mammalian proteins, we determined that 77% had orthologs in Caenorhabditis elegans and 18% were associated with human disease. Of the C. elegans candidates (n=146), we determined that 34 genes functioned in embryonic development and 56% of these were predicted to be membrane trafficking proteins. A secondary, visual screen to detect distinct defects in cell division revealed 21 genes that were necessary for cytokinesis. One of these candidates, OSTD-1, an ER resident protein, was further characterized due to the aberrant cleavage furrow placement and failures in division. We determined that OSTD-1 plays a role in maintaining the dynamic morphology of the ER during the cell cycle. In addition, 65% of all ostd-1 RNAi-treated embryos failed to correctly position cleavage furrows, suggesting that proper ER morphology plays a necessary function during animal cell division.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0077051PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3794981PMC
June 2014

Mitotic spindle proteomics in Chinese hamster ovary cells.

PLoS One 2011 27;6(5):e20489. Epub 2011 May 27.

Department of Genetics, University of Wisconsin-Madison, Madison, Wisconsin, United States of America.

Mitosis is a fundamental process in the development of all organisms. The mitotic spindle guides the cell through mitosis as it mediates the segregation of chromosomes, the orientation of the cleavage furrow, and the progression of cell division. Birth defects and tissue-specific cancers often result from abnormalities in mitotic events. Here, we report a proteomic study of the mitotic spindle from Chinese Hamster Ovary (CHO) cells. Four different isolations of metaphase spindles were subjected to Multi-dimensional Protein Identification Technology (MudPIT) analysis and tandem mass spectrometry. We identified 1155 proteins and used Gene Ontology (GO) analysis to categorize proteins into cellular component groups. We then compared our data to the previously published CHO midbody proteome and identified proteins that are unique to the CHO spindle. Our data represent the first mitotic spindle proteome in CHO cells, which augments the list of mitotic spindle components from mammalian cells.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0020489PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3103581PMC
September 2011

Cell division screens and dynamin.

Biochem Soc Trans 2008 Jun;36(Pt 3):431-5

Department of Genetics, University of Wisconsin-Madison, 425-G Henry Mall, Madison, WI 53706, USA.

Cell division is the most fundamental process in the development of all living organisms. The generation of cell diversity throughout development, the multiplication of cells during wound repair and the maintenance of stem cells in several tissues and organs all rely on proper progress through cell division. Historically, biochemical studies of cell division proved to be difficult, since mitosis is a moving target. The rapid and dynamic nature of mitosis means necessary proteins often exist in multiple isoforms and some for only brief moments during a particular stage in the cell cycle. The advent of proteomics and the introduction of stage-specific inhibitors have enabled the field to identify numerous factors required at distinct steps in the cell cycle. One such factor identified in many of these screens was the highly conserved protein dynamin. Dynamin, long known for its role in endocytosis, is also necessary for co-ordinating actin assembly at membranes. Our knowledge of its precise cell cycle function and upstream/downstream targets, however, is unclear. Our review will describe current knowledge regarding the impacts of several cell division screens and the multiple roles that dynamin may play during mitosis.
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http://dx.doi.org/10.1042/BST0360431DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3660067PMC
June 2008
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