Publications by authors named "Wei-Shan Hsu"

8 Publications

  • Page 1 of 1

Cell cycle regulation of condensin Smc4.

Oncotarget 2019 Jan 8;10(3):263-276. Epub 2019 Jan 8.

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

The condensin complex is a conserved ATPase which promotes the compaction of chromatin during mitosis in eukaryotic cells. Condensin complexes have in addition been reported to contribute to interphase processes including sister chromatid cohesion. It is not understood how condensins specifically become competent to facilitate chromosome condensation in preparation for chromosome segregation in anaphase. Here we describe evidence that core condensin subunits are regulated at the level of protein stability in budding yeast. In particular, Smc2 and Smc4 abundance is cell cycle regulated, peaking at mitosis and falling to low levels in interphase. Smc4 degradation at the end of mitosis is dependent on the Anaphase Promoting Complex/Cyclosome and is mediated by the proteasome. Overproduction of Smc4 results in delayed decondensation, but has a limited ability to promote premature condensation in interphase. Unexpectedly, the Mad2 spindle checkpoint protein is required for mitotic Smc4 degradation. These studies have revealed the novel finding that condensin protein levels are cell cycle regulated and have identified the factors necessary for Smc4 proteolysis.
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http://dx.doi.org/10.18632/oncotarget.26467DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6349450PMC
January 2019

Silver-based wound dressings reduce bacterial burden and promote wound healing.

Int Wound J 2016 Aug 4;13(4):505-11. Epub 2015 Jun 4.

R&D Center, Bio-medical Carbon Technology Co., Ltd., Taichung, Taiwan.

Various types of wound dressings have been designed for different purposes and functions. Controlling bacterial burden in a wound during the early phase is important for successful wound repair. Once bacterial burden is under control, the active promotion of wound healing is another important factor for efficient wound healing. This study investigated the potential of three silver-containing dressings, namely KoCarbonAg(®) , Aquacel(®) Ag and Acticoat 7, in reducing bacterial survival and promoting wound healing. The ability of these dressings to block the entry of bacteria from external environment and retain intrinsic bacteria was studied in vitro. In addition, the study used a rat model to compare the healing efficiencies of the three dressings and investigate the quantity of collagen synthesis in vivo. In vitro results indicated that the silver-containing dressings prevented bacterial growth in wounds by blocking the entry of external bacteria and by retaining the bacteria in the dressing. In vivo study indicated that reduction in bacterial burden accelerated wound healing. Wounds treated by the silver-containing dressings showed better healing than those treated with gauze. Moreover, KoCarbonAg(®) further accelerated wound healing by promoting collagen synthesis and arrangement.
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http://dx.doi.org/10.1111/iwj.12467DOI Listing
August 2016

Evaluation of various silver-containing dressing on infected excision wound healing study.

J Mater Sci Mater Med 2014 May 22;25(5):1375-86. Epub 2014 Jan 22.

Department of Biological Science and Technology, China Medical University, Taichung, Taiwan,

Silver-containing dressings have been widely used for controlling wound infection. However, the relationship between different concentrations of silver in dressings and their antimicrobial activities and wound-healing efficacies remains unclear. In the present study, we (in cooperation with Bio-medical Carbon Technology) investigated various silver-containing activated carbon fibers to understand the effects of different silver concentrations on the efficacies of a silver containing dressing. Our results indicated that various silver-containing activated carbon fibers exhibited good antibacterial effects and biocompatibility in terms of cell viability and that silver concentration showed a minor influence on cell growth. The infected excision wound model indicated that compared to silver-containing activated carbon fiber and other commercial silver-containing dressings assisted wound healing by promoting granulation and collagen deposition. Meanwhile, the silver ion can only be restrained in epidermis by intact skin. During application on the wound area, a temporary increase of serum silver can be detected, but this elevated serum silver level decreased to a subtle level after the removal of silver-containing activated carbon fiber.
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http://dx.doi.org/10.1007/s10856-014-5152-1DOI Listing
May 2014

Direct monitoring of the strand passage reaction of DNA topoisomerase II triggers checkpoint activation.

PLoS Genet 2013 3;9(10):e1003832. Epub 2013 Oct 3.

Department of Genetics, Cell Biology & Development, University of Minnesota, Minneapolis, Minnesota, United States of America.

By necessity, the ancient activity of type II topoisomerases co-evolved with the double-helical structure of DNA, at least in organisms with circular genomes. In humans, the strand passage reaction of DNA topoisomerase II (Topo II) is the target of several major classes of cancer drugs which both poison Topo II and activate cell cycle checkpoint controls. It is important to know the cellular effects of molecules that target Topo II, but the mechanisms of checkpoint activation that respond to Topo II dysfunction are not well understood. Here, we provide evidence that a checkpoint mechanism monitors the strand passage reaction of Topo II. In contrast, cells do not become checkpoint arrested in the presence of the aberrant DNA topologies, such as hyper-catenation, that arise in the absence of Topo II activity. An overall reduction in Topo II activity (i.e. slow strand passage cycles) does not activate the checkpoint, but specific defects in the T-segment transit step of the strand passage reaction do induce a cell cycle delay. Furthermore, the cell cycle delay depends on the divergent and catalytically inert C-terminal region of Topo II, indicating that transmission of a checkpoint signal may occur via the C-terminus. Other, well characterized, mitotic checkpoints detect DNA lesions or monitor unattached kinetochores; these defects arise via failures in a variety of cell processes. In contrast, we have described the first example of a distinct category of checkpoint mechanism that monitors the catalytic cycle of a single specific enzyme in order to determine when chromosome segregation can proceed faithfully.
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http://dx.doi.org/10.1371/journal.pgen.1003832DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3789831PMC
March 2014

Determinants of Rad21 localization at the centrosome in human cells.

Cell Cycle 2010 May 15;9(9):1759-63. Epub 2010 May 15.

Department of Genetics, Cell Biology & Development, University of Minnesota Medical School, Minneapolis, MN, USA.

Cohesin proteins help maintain the physical associations between sister chromatids that arise in S-phase and are removed in anaphase. Recent studies found that cohesins also localize to the centrosomes, the organelles that organize the mitotic bipolar spindle. We find that the cohesin protein Rad21 localizes to centrosomes in a manner that is dependent upon known regulators of sister chromatid cohesion as well as regulators of centrosome function. These data suggest that Rad21 functions at the centrosome and that the regulators of Rad21 coordinate the centrosome and chromosomal functions of cohesin.
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http://dx.doi.org/10.4161/cc.9.9.11523DOI Listing
May 2010

Rad21 is required for centrosome integrity in human cells independently of its role in chromosome cohesion.

Cell Cycle 2010 May 15;9(9):1774-80. Epub 2010 May 15.

Department of Genetics, Cell Biology & Development, University of Minnesota Medical School, Minneapolis, MN, USA.

Classically, chromosomal functions in DNA repair and sister chromatid association have been assigned to the cohesin proteins. More recent studies have provided evidence that cohesins also localize to the centrosomes, which organize the bipolar spindle during mitosis. Depletion of cohesin proteins is associated with multi-polar mitosis in which spindle pole integrity is compromised. However, the spindle pole defects after cohesin depletion could be an indirect consequence of a chromosomal cohesion defect which might impact centrosome integrity via alterations to the spindle microtubule network. Here we show that the cohesin Rad21 is required for centrosome integrity independently of its role as a chromosomal cohesin. Thus, Rad21 may promote accurate chromosome transmission not only by virtue of its function as a chromosomal cohesin, but also because it is required for centrosome function.
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http://dx.doi.org/10.4161/cc.9.9.11524DOI Listing
May 2010

Drosophila decapping protein 1, dDcp1, is a component of the oskar mRNP complex and directs its posterior localization in the oocyte.

Dev Cell 2006 May;10(5):601-13

Institute of Molecular and Cellular Biology, College of Life Science, National Taiwan University, Number 1, Section 4, Roosevelt Road, Taipei, 10617, Taiwan.

In Drosophila, posterior deposition of oskar (osk) mRNA in oocytes is critical for both pole cell and abdomen formation. Exon junction complex components, translational regulation factors, and other proteins form an RNP complex that is essential for directing osk mRNA to the posterior of the oocyte. Until now, it has not been clear whether the mRNA degradation machinery is involved in regulating osk mRNA deposition. Here we show that Drosophila decapping protein 1, dDcp1, is a posterior group gene required for the transport of osk mRNA. In oocytes, dDcp1 is localized posteriorly in an osk mRNA position- and dosage-dependent manner. In nurse cells, dDcp1 colocalizes with dDcp2 and Me31B in discrete foci that may be related to processing bodies (P bodies), which are sites of active mRNA degradation. Thus, as well as being a general factor required for mRNA decay, dDcp1 is an essential component of the osk mRNP localization complex.
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http://dx.doi.org/10.1016/j.devcel.2006.02.021DOI Listing
May 2006

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