Publications by authors named "Kristyn E Vanderwaal"

3 Publications

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bop5 Mutations reveal new roles for the IC138 phosphoprotein in the regulation of flagellar motility and asymmetric waveforms.

Mol Biol Cell 2011 Aug 22;22(16):2862-74. Epub 2011 Jun 22.

Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN 55455, USA.

I1 dynein, or dynein f, is a highly conserved inner arm isoform that plays a key role in the regulation of flagellar motility. To understand how the IC138 IC/LC subcomplex modulates I1 activity, we characterized the molecular lesions and motility phenotypes of several bop5 alleles. bop5-3, bop5-4, and bop5-5 are null alleles, whereas bop5-6 is an intron mutation that reduces IC138 expression. I1 dynein assembles into the axoneme, but the IC138 IC/LC subcomplex is missing. bop5 strains, like other I1 mutants, swim forward with reduced swimming velocities and display an impaired reversal response during photoshock. Unlike mutants lacking the entire I1 dynein, however, bop5 strains exhibit normal phototaxis. bop5 defects are rescued by transformation with the wild-type IC138 gene. Analysis of flagellar waveforms reveals that loss of the IC138 subcomplex reduces shear amplitude, sliding velocities, and the speed of bend propagation in vivo, consistent with the reduction in microtubule sliding velocities observed in vitro. The results indicate that the IC138 IC/LC subcomplex is necessary to generate an efficient waveform for optimal motility, but it is not essential for phototaxis. These findings have significant implications for the mechanisms by which IC/LC complexes regulate dynein motor activity independent of effects on cargo binding or complex stability.
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http://dx.doi.org/10.1091/mbc.E11-03-0270DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3154882PMC
August 2011

A mitotic topoisomerase II checkpoint in budding yeast is required for genome stability but acts independently of Pds1/securin.

Genes Dev 2006 May;20(9):1162-74

Department of Genetics, Cell Biology and Development, University of Minnesota Medical School, Minneapolis, Minnesota 55455, USA.

Topoisomerase II (Topo II) performs topological modifications on double-stranded DNA molecules that are essential for chromosome condensation, resolution, and segregation. In mammals, G2 and metaphase cell cycle delays induced by Topo II poisons have been proposed to be the result of checkpoint activation in response to the catenation state of DNA. However, the apparent lack of such controls in model organisms has excluded genetic proof that Topo II checkpoints exist and are separable from the conventional DNA damage checkpoint controls. But here, we define a Topo II-dependent G2/M checkpoint in a genetically amenable eukaryote, budding yeast, and demonstrate that this checkpoint enhances cell survival. Conversely, a lack of the checkpoint results in aneuploidy. Neither DNA damage-responsive pathways nor Pds1/securin are needed for this checkpoint. Unusually, spindle assembly checkpoint components are required for the Topo II checkpoint, but checkpoint activation is not the result of failed chromosome biorientation or a lack of spindle tension. Thus, compromised Topo II function activates a yeast checkpoint system that operates by a novel mechanism.
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http://dx.doi.org/10.1101/gad.1367206DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1472475PMC
May 2006

Arp2/3 is a negative regulator of growth cone translocation.

Neuron 2004 Jul;43(1):81-94

Biology Department, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.

Arp2/3 is an actin binding complex that is enriched in the peripheral lamellipodia of fibroblasts, where it forms a network of short, branched actin filaments, generating the protrusive force that extends lamellipodia and drives fibroblast motility. Although it has been assumed that Arp2/3 would play a similar role in growth cones, our studies indicate that Arp2/3 is enriched in the central, not the peripheral, region of growth cones and that the growth cone periphery contains few branched actin filaments. Arp2/3 inhibition in fibroblasts severely disrupts actin organization and membrane protrusion. In contrast, Arp2/3 inhibition in growth cones minimally affects actin organization and does not inhibit lamellipodia protrusion or de novo filopodia formation. Surprisingly, Arp2/3 inhibition significantly enhances axon elongation and causes defects in growth cone guidance. These results indicate that Arp2/3 is a negative regulator of growth cone translocation.
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http://dx.doi.org/10.1016/j.neuron.2004.05.015DOI Listing
July 2004