• Journal of Life Science
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• v.26 no.3
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• pp.282-288
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• 2016

Protein-protein interactions regulate the subcellular localization and function of receptors, enzymes, and cytoskeletal proteins. Proteins containing the postsynaptic density-95/disks large/zonula occludens-1 (PDZ) domain have potential to act as scaffolding proteins and play a pivotal role in various processes, such as synaptic plasticity, neural guidance, and development, as well as in the pathophysiology of many diseases. Multi-PDZ domain protein 1 (MUPP1), which has 13 PDZ domains, has a scaffolding function in the clustering of surface receptors, organization of signaling complexes, and coordination of cytoskeletal dynamics. However, the cellular function of MUPP1 has not been fully elucidated. In the present study, a yeast two-hybrid system was used to identify proteins that interacted with the N-terminal PDZ domain of MUPP1. The results revealed an interaction between MUPP1 and Wdpcp (formerly known as Fritz). Wdpcp was identified as a planar cell polarity (PCP) effector, which is known to have a role in collective cell migration and cilia formation. Wdpcp bound to the PDZ1 domain but not to other PDZ domains of MUPP1. The C-terminal end of Wdpcp was essential for the interaction with MUPP1 in the yeast two-hybrid assay. This interaction was further confirmed in a glutathione S-transferase (GST) pull-down assay. When coexpressed in HEK-293T cells, Wdpcp was coimmunoprecipitated with MUPP1. In addition, MUPP1 colocalized with Wdpcp at the same subcellular region in cells. Collectively, these results suggest that the MUPP1-Wdpcp interaction could modulate actin cytoskeleton dynamics and polarized cell migration.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.8
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• pp.3213-3222
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• 2015

Background: Cancer metastasis depends on cell motility which is driven by cycles of actin polymerization and depolymerization. Reactive oxygen species (ROS) and metabolic oxidative stress have long been associated with cancer. ROS play a vital role in regulating actin dynamics that are sensitive to oxidative modification. The current work aimed at studying the effects of sub-lethal metabolic oxidative stress on actin cytoskeleton, focal adhesion and cell migration. Materials and Methods: T47D human breast cancer cells were treated with 2-deoxy-D-glucose (2DG), L-buthionine sulfoximine (BSO), or doxorubicin (DOX), individually or in combination, and changes in intracellular total glutathione and malondialdehyde (MDA) levels were measured. The expression of three major antioxidant enzymes was studied by immunoblotting, and cells were stained with fluorescent-phalloidin to evaluate changes in F-actin organization. In addition, cell adhesion and degradation ability were measured. Cell migration was studied using wound healing and transwell migration assays. Results: Our results show that treating T47D human breast cancer cells with drug combinations (2DG/BSO, 2DG/DOX, or BSO/DOX) decreased intracellular total glutathione and increased oxidized glutathione, lipid peroxidation, and cytotoxicity. In addition, the drug combinations caused a reduction in cell area and mitotic index, prophase arrest and a decreased ability to form invadopodia. The formation of F-actin aggregates was increased in treated T47D cells. Moreover, combination therapy reduced cell adhesion and the rate of cell migration. Conclusions: Our results suggest that exposure of T47D breast cancer cells to combination therapy reduces cell migration via effects on metabolic oxidative stress.

• Journal of Periodontal and Implant Science
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• v.44 no.6
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• pp.266-273
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• 2014

Purpose: We previously reported that human serum significantly reduces the invasion of various oral bacterial species into gingival epithelial cells in vitro. The aims of the present study were to characterize the serum component(s) responsible for the inhibition of bacterial invasion of epithelial cells and to examine their effect on periodontitis induced in mice. Methods: Immortalized human gingival epithelial (HOK-16B) cells were infected with various 5- (and 6-) carboxy-fluorescein diacetate succinimidyl ester-labeled oral bacteria, including Fusobacterium nucleatum, Provetella intermedia, Porphyromonas gingivalis, and Treponiema denticola, in the absence or presence of three major serum components (human serum albumin [HSA], pooled human IgG [phIgG] and ${\alpha}1$-antitrypsin). Bacterial adhesion and invasion were determined by flow cytometry. The levels of intracellular reactive oxygen species (ROS) and activation of small GTPases were examined. Experimental periodontitis was induced by oral inoculation of P. gingivalis and T. denticola in Balb/c mice. Results: HSA and phIgG, but not ${\alpha}1$-antitrypsin, efficiently inhibited the invasion of various oral bacterial species into HOK-16B cells. HSA but not phIgG decreased the adhesion of F. nucleatum onto host cells and the levels of intracellular ROS in HOK-16B cells. N-acetyl-cysteine (NAC), a ROS scavenger, decreased both the levels of intracellular ROS and invasion of F. nucleatum into HOK-16B cells, confirming the role of ROS in bacterial invasion. Infection with F. nucleatum activated Rac1, a regulator of actin cytoskeleton dynamics. Not only HSA and NAC but also phIgG decreased the F. nucleatum-induced activation of Rac1. Furthermore, both HSA plus phIgG and NAC significantly reduced the alveolar bone loss in the experimental periodontitis induced by P. gingivalis and T. denticola in mice. Conclusions: NAC and the serum components HSA and phIgG, which inhibit bacterial invasion of oral epithelial cells in vitro, can successfully prevent experimental periodontitis.