Publications by authors named "Chang-Young Jang"

42 Publications

Wip1 controls the translocation of the chromosomal passenger complex to the central spindle for faithful mitotic exit.

Cell Mol Life Sci 2021 Mar 16;78(6):2821-2838. Epub 2020 Oct 16.

Drug Information Research Institute, College of Pharmacy, Sookmyung Women's University, Seoul, 04310, Republic of Korea.

Dramatic cellular reorganization in mitosis critically depends on the timely and temporal phosphorylation of a broad range of proteins, which is mediated by the activation of the mitotic kinases and repression of counteracting phosphatases. The mitosis-to-interphase transition, which is termed mitotic exit, involves the removal of mitotic phosphorylation by protein phosphatases. Although protein phosphatase 1 (PP1) and protein phosphatase 2A (PP2A) drive this reversal in animal cells, the phosphatase network associated with ordered bulk dephosphorylation in mitotic exit is not fully understood. Here, we describe a new mitotic phosphatase relay in which Wip1/PPM1D phosphatase activity is essential for chromosomal passenger complex (CPC) translocation to the anaphase central spindle after release from the chromosome via PP1-mediated dephosphorylation of histone H3T3. Depletion of endogenous Wip1 and overexpression of the phosphatase-dead mutant disturbed CPC translocation to the central spindle, leading to failure of cytokinesis. While Wip1 was degraded in early mitosis, its levels recovered in anaphase and the protein functioned as a Cdk1-counteracting phosphatase at the anaphase central spindle and midbody. Mechanistically, Wip1 dephosphorylated Thr-59 in inner centromere protein (INCENP), which, subsequently bound to MKLP2 and recruited other components to the central spindle. Furthermore, Wip1 overexpression is associated with the overall survival rate of patients with breast cancer, suggesting that Wip1 not only functions as a weak oncogene in the DNA damage network but also as a tumor suppressor in mitotic exit. Altogether, our findings reveal that sequential dephosphorylation of mitotic phosphatases provides spatiotemporal regulation of mitotic exit to prevent tumor initiation and progression.
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http://dx.doi.org/10.1007/s00018-020-03665-xDOI Listing
March 2021

PRMT6-mediated H3R2me2a guides Aurora B to chromosome arms for proper chromosome segregation.

Nat Commun 2020 01 30;11(1):612. Epub 2020 Jan 30.

Research Institute of Pharmaceutical Sciences, College of Pharmacy, Sookmyung Women's University, Seoul, 04310, Republic of Korea.

The kinase Aurora B forms the chromosomal passenger complex (CPC) together with Borealin, INCENP, and Survivin to mediate chromosome condensation, the correction of erroneous spindle-kinetochore attachments, and cytokinesis. Phosphorylation of histone H3 Thr3 by Haspin kinase and of histone H2A Thr120 by Bub1 concentrates the CPC at the centromere. However, how the CPC is recruited to chromosome arms upon mitotic entry is unknown. Here, we show that asymmetric dimethylation at Arg2 on histone H3 (H3R2me2a) by protein arginine methyltransferase 6 (PRMT6) recruits the CPC to chromosome arms and facilitates histone H3S10 phosphorylation by Aurora B for chromosome condensation. Furthermore, in vitro assays show that Aurora B preferentially binds to the H3 peptide containing H3R2me2a and phosphorylates H3S10. Our findings indicate that the long-awaited key histone mark for CPC recruitment onto mitotic chromosomes is H3R2me2a, which is indispensable for maintaining appropriate CPC levels in dynamic translocation throughout mitosis.
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http://dx.doi.org/10.1038/s41467-020-14511-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6992762PMC
January 2020

c-Cbl Acts as an E3 Ligase Against DDA3 for Spindle Dynamics and Centriole Duplication during Mitosis.

Mol Cells 2019 Dec;42(12):840-849

Drug Information Research Institute, College of Pharmacy, Sookmyung Women's University, Seoul 04310, Korea.

The spatiotemporal mitotic processes are controlled qualitatively by phosphorylation and qualitatively by ubiquitination. Although the SKP1-CUL1-F-box protein (SCF) complex and the anaphase-promoting complex/cyclosome (APC/C) mainly mediate ubiquitin-dependent proteolysis of mitotic regulators, the E3 ligase for a large portion of mitotic proteins has yet to be identified. Here, we report c-Cbl as an E3 ligase that degrades DDA3, a protein involved in spindle dynamics. Depletion of c-Cbl led to increased DDA3 protein levels, resulting in increased recruitment of Kif2a to the mitotic spindle, a concomitant reduction in spindle formation, and chromosome alignment defects. Furthermore, c-Cbl depletion induced centrosome over-duplication and centriole amplification. Therefore, we concluded that c-Cbl controls spindle dynamics and centriole duplication through its E3 ligase activity against DDA3.
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http://dx.doi.org/10.14348/molcells.2019.0142DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6939656PMC
December 2019

Bisphenol A disrupts mitotic progression via disturbing spindle attachment to kinetochore and centriole duplication in cancer cell lines.

Toxicol In Vitro 2019 Sep 11;59:115-125. Epub 2019 Apr 11.

Drug Information Research Institute, College of Pharmacy, Sookmyung Women's University, Seoul 04310, Republic of Korea. Electronic address:

Bisphenol A [BPA, 2,2-bis-(4-hydroxyphenyl)propane] is one of the most prevalent synthetic environmental estrogens; as an endocrine disruptor, it is associated with endocrine-related cancers including breast, ovarian, and prostate. However, the mechanisms by which BPA contributes to carcinogenesis are unclear. This study aims to clarify its toxic effects on mitotic cells and investigate the molecular mechanism. In vitro effects of BPA on mitotic progression were examined by performing experiments on HeLa cells. Proteins involved in mitotic processes were detected by Western blot, live cell imaging, and immunofluorescence staining. The results showed that BPA increased chromosomal instability by perturbing mitotic processes such as bipolar spindle formation and spindle microtubule attachment to the kinetochore. BPA prolonged mitotic progression by disturbing spindle attachment and concomitant activating spindle assembly checkpoint (SAC). Mechanistically, BPA interfered proper localization of HURP to the proximal ends of spindle microtubules, Kif2a to the minus ends of spindle microtubules, and TPX2 on the mitotic spindle. This mislocalization of microtubule associated proteins (MAPs) is postulated to lead to spindle attachment failure. Furthermore, BPA caused multipolar spindle by inducing centriole overduplication and premature disengagement. Although BPA acts as an estrogen receptor (ER) agonist, mitotic defects caused by BPA occurred in an ER-independent manner. Our findings indicate that BPA may stimulate carcinogenesis not only by acting as an endocrine disruptor but also by increasing chromosomal instability during mitosis.
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http://dx.doi.org/10.1016/j.tiv.2019.04.009DOI Listing
September 2019

Characterization of Soybean Germinated Embryo Extract as an Estrogen Receptor Subtype-Selective and Tissue-Specific Modulator.

J Med Food 2019 Feb 26;22(2):186-195. Epub 2018 Dec 26.

2 Department of Biological Sciences, Sookmyung Women's University, Seoul, Korea.

Phytoestrogens possess beneficial effects in the management of menopausal symptoms with few side effects. Soybeans are major natural sources of isoflavones, with high estrogen receptor (ER)-β selectivity. The objective of this study therefore was to develop a solvent-mediated extraction method for soybean germinated embryos (SGEs) and to investigate the biological activities of the extract. Ethanolic extraction yielded the SGE extract (SGEE), which had a unique composition of biologically active aglycones and soyasaponins. SGEE showed a proliferative effect in MCF7 cells and ERβ-selective transcriptional activities in human embryonic kidney cells. In addition, oral administration of SGEE to ovariectomized rats resulted in the induction of ERβ and estrogen-responsive genes in the uterus and a decrease in tail skin temperature and uterus weight. Our data suggest that germination and ethanolic extraction are effective measures for producing isoflavone-rich food supplements, which may be useful as alternative menopausal hormone therapy.
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http://dx.doi.org/10.1089/jmf.2018.4250DOI Listing
February 2019

Hepatic Metabolism of Sakuranetin and Its Modulating Effects on Cytochrome P450s and UDP-Glucuronosyltransferases.

Molecules 2018 Jun 26;23(7). Epub 2018 Jun 26.

Department of Biological Sciences and Research Institute of Women's Health, Sookmyung Women's University, Seoul 04310, Korea.

Sakuranetin (SKN), found in cherry trees and rice, is a flavanone with various pharmacological activities. It is biosynthesized from naringenin in rice or cherry trees, and the metabolism of SKN has been studied in non-human species. The present study aimed to investigate the metabolic pathways of SKN in human liver microsomes and identify the phase I and phase II metabolites, as well as evaluate the potential for drug⁻herb interactions through the modulation of drug metabolizing enzymes (DMEs). HPLC-DAD and HPLC-electrospray mass spectrometry were used to study the metabolic stability and identify the metabolites from human liver microsomes incubated with SKN. The potential of SKN to inhibit the DMEs was evaluated by monitoring the formation of a DME-specific product. The cytochrome P450 2B6 and 3A4-inductive effects were studied using promoter reporter assays in human hepatocarcinoma cells. The major pathways for SKN metabolism include B-ring hydroxylation, 5--demethylation, and conjugation with glutathione or glucuronic acid. The phase I metabolites were identified as naringenin and eriodictyol. SKN was found to be a UDP-glucuronosyltransferases (UGT) 1A9 inhibitor, whereas it induced transactivation of the human pregnane X receptor-mediated cytochrome P450 (CYP) 3A4 gene.
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http://dx.doi.org/10.3390/molecules23071542DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6100415PMC
June 2018

Modulating cellular balance of Rps3 mono-ubiquitination by both Hel2 E3 ligase and Ubp3 deubiquitinase regulates protein quality control.

Exp Mol Med 2017 11 17;49(11):e390. Epub 2017 Nov 17.

Laboratory of Biochemistry, Division of Life Sciences, Korea University, Seoul, Republic of Korea.

When a ribosome complex is stalled during the translation elongation process in eukaryotes, the mono-ubiquitination of Rps3 has recently been shown to be critical to ribosome quality control. We have discovered that the regulatory role of Rps3 mono-ubiquitination is controlled by a deubiquitinase. We also showed that an autophagic signal appears to be coupled to the mono-ubiquitination of Rps3p through the entrance of Ubp3p into the autophagosome in yeasts. The mono-ubiquitination of the Rps3 protein is tightly modulated by reciprocal action between the Hel2p E3 ligase and the Ubp3p deubiquitinase in yeasts and the reciprocal action between the RNF123 E3 ligase and the USP10 deubiquitinase in mammalian cells. We also found that the Ubp3p/USP10 deubiquitinases critically modulate Hel2p/RNF123-mediated Rps3p mono-ubiquitination. In addition, we found that Hel2p/RNF123 and Ubp3p/USP10 appeared to be differently localized in the ribosome complex after ultraviolet irradiation. Together, our results support a model in which coordinated ubiquitination and deubiquitination activities can finely balance the level of regulatory Rps3p mono-ubiquitination in ribosome-associated quality control and autophagy processes.
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http://dx.doi.org/10.1038/emm.2017.128DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5704183PMC
November 2017

The tobacco carcinogen NNK disturbs mitotic chromosome alignment by interrupting p53 targeting to the centrosome.

Toxicol Lett 2017 Nov 28;281:110-118. Epub 2017 Sep 28.

Research Center for Cell Fate Control, College of Pharmacy, Sookmyung Women's University, Seoul 04310, Republic of Korea. Electronic address:

The tobacco-specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is the most potent risk factor among tobacco-related carcinogens in lung cancer progression and outcomes. Although genetic mutations and chromosome instability have been detected in NNK-induced lung tumors, the oncogenic mechanisms of NNK are not fully understood. Here, we show that NNK increases chromosomal instability by disrupting spindle microtubule (MT) attachment to the kinetochore (KT) and spindle dynamics. Mechanistically, NNK blocks the targeting of p53 to the centrosome during mitosis, leading to chromosome alignment defects in metaphase. Therefore, lung cancer cells with wild-type p53, such as A594 and H226B, are more resistant to the NNK treatment than p53-mutant lung cancer cells, such as A1299 and H226Br. Although NNK does not affect the levels or transcriptional activity of p53, the reduction of the p53 level at the centrosome exacerbates the NNK-induced chromosome alignment defect in A549 and H226B cells. Therefore, p53 protects against NNK-induced chromosome instability by modulating the function of centrosome-localized p53 and not by modulating transcriptional activity. We conclude that NNK may increase the risk of lung cancer progression and poorer outcomes in patients with p53 mutations by perturbing proper mitotic progression and chromosome integrity.
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http://dx.doi.org/10.1016/j.toxlet.2017.09.019DOI Listing
November 2017

TC Mps1 12, a novel Mps1 inhibitor, suppresses the growth of hepatocellular carcinoma cells via the accumulation of chromosomal instability.

Br J Pharmacol 2017 06 22;174(12):1810-1825. Epub 2017 Apr 22.

Department of Biomedical Science, Graduate School, Kyung Hee University, Seoul, Republic of Korea.

Background And Purpose: Chromosomal instability is not only a hallmark of cancer but also an attractive therapeutic target. A diverse set of mitotic kinases maintains chromosomal stability. One of these is monopolar spindle 1 (Mps1, also known as TTK), which is essential for chromosome alignment and for the spindle assembly checkpoint (SAC). Pharmacological inhibition of Mps1 has been suggested as a cancer therapeutic; however, despite the existence of a novel Mps1 inhibitor, TC Mps1 12, no such studies have been performed.

Experimental Approach: The effects of TC Mps1 12 on cell viability, chromosome alignment, centrosome number, mitotic duration, apoptosis and SAC were determined in hepatocellular carcinoma (HCC) cells. In addition, the association of Mps1 expression with the overall survival of HCC patients was analysed.

Key Results: Treatment of human HCC cells with TC Mps1 12 led to chromosome misalignment and missegregation, and disorganization of centrosomes. Even in the presence of these errors, TC Mps1 12-treated cells overrode the SAC, resulting in a shortened mitotic duration and mitotic slippage. This mitotic catastrophe triggered apoptosis and, finally, inhibited the growth of HCC cells. In addition, the expression of the Mps1-encoding TTK gene was associated with poor overall survival of HCC patients.

Conclusion And Implications: TC Mps1 12 results in the accumulation of chromosomal instabilities and mitotic catastrophe in HCC cells. Overall, these data demonstrate that the inhibition of Mps1 kinase using TC Mps1 12 is a promising therapeutic approach for liver cancer.
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http://dx.doi.org/10.1111/bph.13782DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5446587PMC
June 2017

Characterization of Phase I and Phase II Hepatic Metabolism and Reactive Intermediates of Larrea nitida Cav. and Its Lignan Compounds.

Phytother Res 2017 Jan 7;31(1):140-151. Epub 2016 Nov 7.

Department of Biological Sciences, College of Science, Sookmyung Women's University, 100, Chungparo 47-gil, Seoul, 140-742, Korea.

Larrea nitida Cav. (LNC), which belongs to the family Zygophyllaceae, is widely indigenous and used in South America to treat various pathological conditions. It contains the antioxidant and antiinflammatory but toxic nordihydroguaiaretic acid (NDGA) as well as O-methylated metabolite of NDGA (MNDGA) as bioactive compounds. The hepatic metabolism-based toxicological potential of extracts of LNC (LNE), NDGA, and MNDGA has not previously been reported. The present study aimed to characterize the phase I and phase II hepatic metabolism and reactive intermediates of LNE, NDGA, and MNDGA and their effects on the major drug-metabolizing enzymes in vitro and ex vivo. A methanol extract of LNC collected from Chile as well as NDGA and MNDGA isolated from LNE were subjected to metabolic stability assays in liver microsomes in the presence of the cofactors reduced nicotinamide dinucleotide phosphate (NADPH) and/or uridine 5'-diphosphoglucuronic acid (UDPGA). Cytochrome P450 (CYP) inhibition assays were performed using CYP isozyme-specific model substrates to examine the inhibitory activities of LNE, NDGA, and MNDGA, which were expressed as % inhibition and IC values. Ex vivo CYP induction potential was investigated in the liver microsomes prepared from the rats intraperitoneally administered with LNE. Glutathione (GSH) adduct formation was monitored by LC-MS analysis of the microsomal incubation samples with either NDGA or MNDGA and an excess of GSH to determine the formation of electrophilic reactive intermediates. Both NDGA and MNDGA were stable to NADPH-dependent phase I metabolism, but labile to glucuronide conjugation. LNE, NDGA, and MNDGA showed significant inhibitory effects on CYP1A2, 2C9, 2D6, and/or 3A4, with IC values in the micromolar range. LNE was found to be a CYP1A2 inducer in ex vivo rat experiments, and mono- and di-GSH adducts of both NDGA and MNDGA were identified by LC-MS analysis. Our study suggests that hepatic clearance is the major elimination route for the lignans NDGA and MNDGA present in LNE. These lignans may possess the ability to modify biomacromolecules via producing reactive intermediates. In addition, LNE, NDGA, and MNDGA are found to be inhibitors for various CYP isozymes such as CYP2C9 and 3A4. Thus, the consumption of LNC as an herbal preparation or NDGA may cause metabolism-driven herb-drug interactions. Copyright © 2016 John Wiley & Sons, Ltd.
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http://dx.doi.org/10.1002/ptr.5742DOI Listing
January 2017

Phosphorylation of Astrin Regulates Its Kinetochore Function.

J Biol Chem 2016 08 20;291(34):17579-92. Epub 2016 Jun 20.

Research Center for Cell Fate Control, College of Pharmacy, Sookmyung Women's University, Seoul 04310, Republic of Korea

The error-free segregation of chromosomes, which requires the precisely timed search and capture of chromosomes by spindles during early mitotic and meiotic cell division, is responsible for genomic stability and is achieved by the spindle assembly checkpoint in the metaphase-anaphase transition. Mitotic kinases orchestrate M phase events, such as the reorganization of cell architecture and kinetochore (KT) composition with the exquisite phosphorylation of mitotic regulators, to ensure timely and temporal progression. However, the molecular mechanisms underlying the changes of KT composition for stable spindle attachment during mitosis are poorly understood. Here, we show that the sequential action of the kinase Cdk1 and the phosphatase Cdc14A control spindle attachment to KTs. During prophase, the mitotic spindle protein Spag5/Astrin is transported into centrosomes by Kinastrin and phosphorylated at Ser-135 and Ser-249 by Cdk1, which, in prometaphase, is loaded onto the spindle and targeted to KTs. We also demonstrate that Cdc14A dephosphorylates Astrin, and therefore the overexpression of Cdc14A sequesters Astrin in the centrosome and results in aberrant chromosome alignment. Mechanistically, Plk1 acts as an upstream kinase for Astrin phosphorylation by Cdk1 and targeting phospho-Astrin to KTs, leading to the recruitment of outer KT components, such as Cenp-E, and the stable attachment of spindles to KTs. These comprehensive findings reveal a regulatory circuit for protein targeting to KTs that controls the KT composition change of stable spindle attachment and chromosome integrity.
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http://dx.doi.org/10.1074/jbc.M115.712745DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5016155PMC
August 2016

DDA3 and Mdp3 modulate Kif2a recruitment onto the mitotic spindle to control minus-end spindle dynamics.

J Cell Sci 2016 07 9;129(14):2719-25. Epub 2016 Jun 9.

Research Center for Cell Fate Control, College of Pharmacy, Sookmyung Women's University, Seoul 140-742, Republic of Korea

Active turnover of spindle microtubules (MTs) for the formation of a bi-orientated spindle, chromosome congression and proper chromosome segregation is regulated by MT depolymerases such as the kinesin-13 family and the plus-end-tracking proteins (+TIPs). However, the control mechanisms underlying the spindle MT dynamics that are responsible for poleward flux at the minus end of MTs are poorly understood. Here, we show that Mdp3 (also known as MAP7D3) forms a complex with DDA3 (also known as PSRC1) and controls spindle dynamics at the minus end of MTs by inhibiting DDA3-mediated Kif2a recruitment to the spindle. Aberrant Kif2a activity at the minus end of spindle MTs in Mdp3-depleted cells decreased spindle stability and resulted in unaligned chromosomes in metaphase, lagging chromosomes in anaphase, and chromosome bridges in telophase and cytokinesis. Although they play opposing roles in minus-end MT dynamics, acting as an MT destabilizer and an MT stabilizer, respectively, DDA3 and Mdp3 did not affect the localization of each other. Thus, the DDA3 complex orchestrates MT dynamics at the MT minus end by fine-tuning the recruitment of Kif2a to regulate minus-end MT dynamics and poleward MT flux at the mitotic spindle.
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http://dx.doi.org/10.1242/jcs.180109DOI Listing
July 2016

Hyaluronan-conjugated liposomes encapsulating gemcitabine for breast cancer stem cells.

Int J Nanomedicine 2016 5;11:1413-25. Epub 2016 Apr 5.

Research Center for Cell Fate Control (RCCFC) and College of Pharmacy, Sookmyung Women's University, Seoul, Korea.

Investigation of potential therapeutics for targeting breast cancer stem cells (BCSCs) is important because these cells are regarded as culprit of breast cancer relapse. Accomplishing this kind of strategy requires a specific drug-delivery system using the distinct features of liposomes. Studies on targeted liposomal delivery systems have indicated the conjugation of hyaluronan (HA), a primary ligand for CD44 surface markers, as an appropriate method for targeting BCSCs. For this study, enriched BCSCs were obtained by culturing MCF-7 breast cancer cells in nonadherent conditions. The enriched BCSCs were challenged with HA-conjugated liposomes encapsulating gemcitabine (2, 2-difluoro-2-deoxycytidine, GEM). In vitro study showed that the HA-conjugated liposomes significantly enhanced the cytotoxicity, anti-migration, and anti-colony formation abilities of GEM through targeting of CD44 expressed on BCSCs. In pharmacokinetic study, area under the drug concentration vs time curve (AUC) of the immunoliposomal GEM was 3.5 times higher than that of free GEM, indicating that the HA-conjugated liposomes enhanced the stability of GEM in the bloodstream and therefore prolonged its half-life time. The antitumor effect of the immunoliposomal GEM was 3.3 times higher than that of free GEM in a xenograft mouse model, probably reflecting the unique targeting of the CD44 receptor by HA and the increased cytotoxicity and stability through the liposomal formulation. Furthermore, marginal change in body weight demonstrated that the use of liposomes considerably reduced the systemic toxicity of GEM on normal healthy cells. Taken together, this study demonstrates that HA-conjugated liposomes encapsulating GEM show promise for the therapy of breast cancer in vitro and in a xenograft model by targeting the BCSCs.
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http://dx.doi.org/10.2147/IJN.S95850DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4827594PMC
October 2016

Evaluation of the Biological Activity of Opuntia ficus indica as a Tissue- and Estrogen Receptor Subtype-Selective Modulator.

Phytother Res 2016 Jun 14;30(6):971-80. Epub 2016 Mar 14.

Department of Medical and Pharmaceutical Science, College of Science, Sookmyung Women's University, 100, Chungparo 47-gil, Seoul, 140-742, Republic of Korea.

Phytoestrogens are selective estrogen receptor modulators (SERMs) with potential for use in hormone replacement therapy (HRT) to relieve peri/postmenopausal symptoms. This study was aimed at elucidating the molecular mechanisms underlying the SERM properties of the extract of Korean-grown Opuntia ficus-indica (KOFI). The KOFI extract induced estrogen response element (ERE)-driven transcription in breast and endometrial cancer cell lines and the expression of endogenous estrogen-responsive genes in breast cancer cells. The flavonoid content of different KOFI preparations affected ERE-luciferase activities, implying that the flavonoid composition likely mediated the estrogenic activities in cells. Oral administration of KOFI decreased the weight gain and levels of both serum glucose and triglyceride in ovariectomized (OVX) rats. Finally, KOFI had an inhibitory effect on the 17β-estradiol-induced proliferation of the endometrial epithelium in OVX rats. Our data demonstrate that KOFI exhibited SERM activity with no uterotrophic side effects. Therefore, KOFI alone or in combination with other botanical supplements, vitamins, or minerals may be an effective and safe alternative active ingredient to HRTs, for the management of postmenopausal symptoms. Copyright © 2016 John Wiley & Sons, Ltd.
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http://dx.doi.org/10.1002/ptr.5602DOI Listing
June 2016

IK-guided PP2A suppresses Aurora B activity in the interphase of tumor cells.

Cell Mol Life Sci 2016 09 23;73(17):3375-86. Epub 2016 Feb 23.

Division of Biological Sciences, Department of Life Systems, Research Center for Women's Disease, Sookmyung Women's University, Seoul, 140-742, Republic of Korea.

Aurora B activation is triggered at the mitotic entry and required for proper microtubule-kinetochore attachment at mitotic phase. Therefore, Aurora B should be in inactive form in interphase to prevent aberrant cell cycle progression. However, it is unclear how the inactivation of Aurora B is sustained during interphase. In this study, we find that IK depletion-induced mitotic arrest leads to G2 arrest by Aurora B inhibition, indicating that IK depletion enhances Aurora B activation before mitotic entry. IK binds to Aurora B, and colocalizes on the nuclear foci during interphase. Our data further show that IK inhibits Aurora B activation through recruiting PP2A into IK and Aurora B complex. It is thus believed that IK, as a scaffold protein, guides PP2A into Aurora B to suppress its activity in interphase until mitotic entry.
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http://dx.doi.org/10.1007/s00018-016-2162-9DOI Listing
September 2016

ANKRD53 interacts with DDA3 and regulates chromosome integrity during mitosis.

Biochem Biophys Res Commun 2016 Feb 25;470(3):484-491. Epub 2016 Jan 25.

Research Center for Cell Fate Control, College of Pharmacy, Sookmyung Women's University, Seoul 140-742, Republic of Korea. Electronic address:

Spindle dynamics drives chromosome movement and mitotic progression during mitosis. Microtubule (MT)-associated proteins (MAPs) regulate MT stabilization/destabilization and MT polymerization/depolymerization for congression of sister chromatids at the mitotic equator and subsequent segregation toward the spindle poles. Here, we identified ANKRD53 as a novel DDA3-interacting protein through proteomic analysis. Based on expression profiles, ANKRD53 is phosphorylated by mitotic kinases during mitosis. In ANKRD53-depleted HeLa cells, the progression of mitosis was delayed and the number of unaligned chromosomes increased substantially. In addition, spindle MT polymerization decreased and the spindle assembly checkpoint (SAC) was concomitantly activated by the decreased spindle dynamics in ANKRD53-depleted cells. Although ANKRD53 is recruited to the mitotic spindle by DDA3, it counteracts the activity of DDA3 for spindle MT polymerization. Furthermore, ANKRD53 depletion increased the number of bi-nuclei and polylobed nuclei. Thus, ANKRD53 is recruited to the mitotic spindle by DDA3 and acts as a regulator of spindle dynamics and cytokinesis.
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http://dx.doi.org/10.1016/j.bbrc.2016.01.144DOI Listing
February 2016

Ska1 cooperates with DDA3 for spindle dynamics and spindle attachment to kinetochore.

Biochem Biophys Res Commun 2016 Feb 19;470(3):586-592. Epub 2016 Jan 19.

Research Center for Cell Fate Control, College of Pharmacy, Sookmyung Women's University, Seoul 140-742, Republic of Korea. Electronic address:

Spindle microtubules (MTs) capture kinetochores (KTs) on the centromere sequence of sister chromatids to align at the mitotic equator and segregate toward spindle poles during mitosis. For efficient chromosome capture, KTs initially attach to the lateral surface of a MT, providing a considerably larger contact surface than the MT tip. A sequential change of KT composition upon spindle attachment enables a conversion from lateral to stable end-on attachment. However, the molecular link between spindle dynamics and KT composition is not fully understood. Here, we report that Ska1 and DDA3 act as molecular linkers in the interplay between KTs and spindle dynamics. After recruitment of Kif2a onto the mitotic spindle by DDA3, Ska1 targets Kif2a to the minus-end of spindle MTs and facilitates spindle dynamics. Furthermore, DDA3 targets Ska1 to KTs to stabilize end-on attachment. Thus, our findings identified a definite regulatory mechanism of the search and capture process for stable spindle attachment through cross-talk between spindle dynamics and KT composition mediated by DDA3 and Ska1.
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http://dx.doi.org/10.1016/j.bbrc.2016.01.101DOI Listing
February 2016

DDA3 targets Cep290 into the centrosome to regulate spindle positioning.

Biochem Biophys Res Commun 2015 Jul 17-24;463(1-2):88-94. Epub 2015 May 18.

Research Center for Cell Fate Control, College of Pharmacy, Sookmyung Women's University, Seoul 140-742, Republic of Korea. Electronic address:

The centrosome is an important cellular organelle which nucleates microtubules (MTs) to form the cytoskeleton during interphase and the mitotic spindle during mitosis. The Cep290 is one of the centrosomal proteins and functions in cilia formation. Even-though it is in the centrosome, the function of Cep290 in mitosis had not yet been evaluated. In this study, we report a novel function of Cep290 that is involved in spindle positioning. Cep290 was identified as an interacting partner of DDA3, and we confirmed that Cep290 specifically localizes in the mitotic centrosome. Depletion of Cep290 caused a reduction of the astral spindle, leading to misorientation of the mitotic spindle. MT polymerization also decreased in Cep290-depleted cells, suggesting that Cep290 is involved in spindle nucleation. Furthermore, DDA3 stabilizes and transports Cep290 to the centrosome. Therefore, we concluded that DDA3 controls astral spindle formation and spindle positioning by targeting Cep290 to the centrosome.
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http://dx.doi.org/10.1016/j.bbrc.2015.05.028DOI Listing
August 2015

Sirt1 Regulates Microtubule Dynamics Through Negative Regulation of Plk1 in Mitosis.

J Cell Biochem 2015 Sep;116(9):1888-97

College of Natural Sciences, Department of Life Sciences, Sogang University, Seoul, 121-742, Republic of Korea.

Although loss of Sirt1 leads to chromosome aneuploidy, which accounts for higher tumor susceptibility, the molecular mechanisms remain unclear. Herein, we demonstrate that Sirt1 directly regulates Plk1, of which activity is critical for mitotic progression and spindle dynamics. Depletion or inhibition of Sirt1 significantly perturbs the formation of the mitotic spindle, leading to defective chromosome segregation. Elevated depolymerization of the mitotic spindle following loss of Sirt1 was associated with the deregulation of Plk1 activity. Thus, we conclude that Sirt1 may contribute to a mitotic regulator that controls spindle dynamics through Plk1 activity, resulting in fine-tuning of Plk1 dependent microtubule dynamics.
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http://dx.doi.org/10.1002/jcb.25144DOI Listing
September 2015

ERα regulates chromosome alignment and spindle dynamics during mitosis.

Biochem Biophys Res Commun 2015 Jan 19;456(4):919-25. Epub 2014 Dec 19.

Research Center for Cell Fate Control, College of Pharmacy, Sookmyung Women's University, Seoul 140-742, Republic of Korea. Electronic address:

Estrogen receptors are activated by the hormone estrogen and they control cell growth by altering gene expression as a transcription factor. So far two estrogen receptors have been found: ERα and ERβ. Estrogen receptors are also implicated in the development and progression of breast cancer. Here, we found that ERα localized on the spindle and spindle poles at the metaphase during mitosis. Depletion of ERα generated unaligned chromosomes in metaphase cells and lagging chromosomes in anaphase cells in a transcription-independent manner. Furthermore, the levels of β-tubulin and γ-tubulin were reduced in ERα-depleted cells. Consistent with this, polymerization of microtubules in ERα-depleted cells and turnover rate of α/β-tubulin were decreased than in control cells. We suggest that ERα regulates chromosome alignment and spindle dynamics by stabilizing microtubules during mitosis.
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http://dx.doi.org/10.1016/j.bbrc.2014.12.062DOI Listing
January 2015

Sirt3 controls chromosome alignment by regulating spindle dynamics during mitosis.

Biochem Biophys Res Commun 2014 Feb 1;444(4):662-9. Epub 2014 Feb 1.

Research Center for Cell Fate Control, College of Pharmacy, Sookmyung Women's University, Seoul 140-742, Republic of Korea. Electronic address:

Sirt3, one of mammalian sirtuins is a prominent mitochondrial deacetylase that controls mitochondrial oxidative pathways and the rate of reactive oxygen species. Sirt3 also regulates energy metabolism by deacetylating enzymes involved in the metabolic pathway related with lifespan. We report here a novel function of Sirt3 which was found to be involved in mitosis. Depletion of the Sirt3 protein generated unaligned chromosomes in metaphase which caused mitotic arrest by activating spindle assembly checkpoint (SAC). Furthermore, the shape and the amount of the spindles in Sirt3 depleted cells were abnormal. Microtubule (MT) polymerization also increased in Sirt3 depleted cells, suggesting that Sirt3 is involved in spindle dynamics. However, the level of acetylated tubulin was not increased significantly in Sirt3 depleted cells. The findings collectively suggest that Sirt3 is not a tubulin deacetylase but regulates the attachment of spindle MTs to the kinetochore and the subsequent chromosome alignment by increasing spindle dynamics.
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http://dx.doi.org/10.1016/j.bbrc.2014.01.124DOI Listing
February 2014

Tussilagone suppresses colon cancer cell proliferation by promoting the degradation of β-catenin.

Biochem Biophys Res Commun 2014 Jan 22;443(1):132-7. Epub 2013 Nov 22.

College of Pharmacy and Research Center for Cell Fate Control, Sookmyung Women's University, 52 Hyochangwon-Gil, Yongsan-Gu, Seoul 140-742, Republic of Korea. Electronic address:

Abnormal activation of the Wnt/β-catenin signaling pathway frequently induces colon cancer progression. In the present study, we identified tussilagone (TSL), a compound isolated from the flower buds of Tussilago farfara, as an inhibitor on β-catenin dependent Wnt pathway. TSL suppressed β-catenin/T-cell factor transcriptional activity and down-regulated β-catenin level both in cytoplasm and nuclei of HEK293 reporter cells when they were stimulated by Wnt3a or activated by an inhibitor of glycogen synthase kinase-3β. Since the mRNA level was not changed by TSL, proteasomal degradation might be responsible for the decreased level of β-catenin. In SW480 and HCT116 colon cancer cell lines, TSL suppressed the β-catenin activity and also decreased the expression of cyclin D1 and c-myc, representative target genes of the Wnt/β-catenin signaling pathway, and consequently inhibited the proliferation of colon cancer cells. Taken together, TSL might be a potential chemotherapeutic agent for the prevention and treatment of human colon cancer.
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http://dx.doi.org/10.1016/j.bbrc.2013.11.062DOI Listing
January 2014

Cancerous inhibitor of protein phosphatase 2A (CIP2A) protein is involved in centrosome separation through the regulation of NIMA (never in mitosis gene A)-related kinase 2 (NEK2) protein activity.

J Biol Chem 2014 Jan 8;289(1):28-40. Epub 2013 Nov 8.

From the Research Center for Women's Disease, Department of Life Systems and.

Cancerous inhibitor of protein phosphatase 2A (CIP2A) is overexpressed in most human cancers and has been described as being involved in the progression of several human malignancies via the inhibition of protein phosphatase 2A (PP2A) activity toward c-Myc. However, with the exception of this role, the cellular function of CIP2A remains poorly understood. On the basis of yeast two-hybrid and coimmunoprecipitation assays, we demonstrate here that NIMA (never in mitosis gene A)-related kinase 2 (NEK2) is a binding partner for CIP2A. CIP2A exhibited dynamic changes in distribution, including the cytoplasm and centrosome, depending on the cell cycle stage. When CIP2A was depleted, centrosome separation and the mitotic spindle dynamics were impaired, resulting in the activation of spindle assembly checkpoint signaling and, ultimately, extension of the cell division time. Our data imply that CIP2A strongly interacts with NEK2 during G2/M phase, thereby enhancing NEK2 kinase activity to facilitate centrosome separation in a PP1- and PP2A-independent manner. In conclusion, CIP2A is involved in cell cycle progression through centrosome separation and mitotic spindle dynamics.
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http://dx.doi.org/10.1074/jbc.M113.507954DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3879551PMC
January 2014

Ribosomal protein S3 localizes on the mitotic spindle and functions as a microtubule associated protein in mitosis.

Biochem Biophys Res Commun 2012 Dec 3;429(1-2):57-62. Epub 2012 Nov 3.

Laboratory of Biochemistry, School of Life Sciences and Biotechnology, Korea University, Seoul 136-701, Republic of Korea.

The human ribosomal protein S3 (rpS3) has multi-functions such as translation, DNA repair and apoptosis. These multiple functions are regulated by post-translational modifications including phosphorylation, methylation and sumoylation. We report here a novel function of rpS3 that is involved in mitosis. When we examined localization of ribosomal proteins in mitosis, we found that rpS3 specifically localizes on the mitotic spindle. Depletion of the rpS3 proteins caused mitotic arrest during the metaphase. Furthermore, the shape of the spindle and chromosome movement in the rpS3 depleted cell was abnormal. Microtubule (MT) polymerization also decreased in rpS3 depleted cells, suggesting that rpS3 is involved in spindle dynamics. Therefore, we concluded that rpS3 acts as a microtubule associated protein (MAP) and regulates spindle dynamics during mitosis.
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http://dx.doi.org/10.1016/j.bbrc.2012.10.093DOI Listing
December 2012

5-Lipoxygenase mediates RANKL-induced osteoclast formation via the cysteinyl leukotriene receptor 1.

J Immunol 2012 Dec 29;189(11):5284-92. Epub 2012 Oct 29.

College of Pharmacy, Sookmyung Women's University, Seoul 140-742, Republic of Korea.

5-Lipoxygenase (5-LO) catalyzes the formation of two major groups of leukotrienes, leukotriene B4 and cysteinyl leukotrienes (CysLTs), and it has been implicated as a promising drug target to treat various inflammatory diseases. However, its role in osteoclastogenesis has not been investigated. In this study, we used mouse bone marrow-derived macrophages (BMMs) to show that 5-LO inhibitor suppresses RANKL-induced osteoclast formation. Inhibition of 5-LO was associated with impaired activation of multiple signaling events downstream of RANK, including ERK and p38 phosphorylation, and IκB degradation, followed by a decrease in NFATc1 expression. Ectopic overexpression of a constitutively active form of NFATc1 partly rescued the antiosteoclastogenic effect of 5-LO inhibitor. The knockdown of 5-LO in BMMs also resulted in a significant reduction in RANKL-induced osteoclast formation, accompanied by decreased expression of NFATc1. Similar effects were shown with CysLT receptor (CysLTR)1/2 antagonist and small RNA for CysLTR1 in BMMs, indicating the involvement of CysLT and CysLTR1 in 5-LO-mediated osteoclastogenesis. Finally, 5-LO inhibitor suppressed LPS-induced osteoclast formation and bone loss in the in vivo mouse experiments, suggesting a potential therapeutic strategy for treating diseases involving bone destruction. Taken together, the results of this study demonstrate that 5-LO is a key mediator of RANKL-induced osteoclast formation and possibly a novel therapeutic target for bone-resorption diseases.
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http://dx.doi.org/10.4049/jimmunol.1003738DOI Listing
December 2012

Phenylbutyric acid induces the cellular senescence through an Akt/p21(WAF1) signaling pathway.

Biochem Biophys Res Commun 2012 Jun 23;422(2):213-8. Epub 2012 Apr 23.

Laboratory of Biochemistry, School of Life Sciences and Biotechnology, and BioInstitute, Korea University, Seoul 136-701, Republic of Korea.

It has been well known that three sentinel proteins - PERK, ATF6 and IRE1 - initiate the unfolded protein response (UPR) in the presence of misfolded or unfolded proteins in the ER. Recent studies have demonstrated that upregulation of UPR in cancer cells is required to survive and proliferate. Here, we showed that long exposure to 4-phenylbutyric acid (PBA), a chemical chaperone that can reduce retention of unfolded and misfolded proteins in ER, induced cellular senescence in cancer cells such as MCF7 and HT1080. In addition, we found that treatment with PBA activates Akt, which results in p21(WAF1) induction. Interestingly, the depletion of PERK but not ATF6 and IRE1 also induces cellular senescence, which was rescued by additional depletion of Akt. This suggests that Akt pathway is downstream of PERK in PBA induced cellular senescence. Taken together, these results show that PBA induces cellular senescence via activation of the Akt/p21(WAF1) pathway by PERK inhibition.
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http://dx.doi.org/10.1016/j.bbrc.2012.04.086DOI Listing
June 2012

Ribosomal protein S3 interacts with TRADD to induce apoptosis through caspase dependent JNK activation.

Biochem Biophys Res Commun 2012 May 9;421(3):474-8. Epub 2012 Apr 9.

Laboratory of Biochemistry, School of Life Sciences and Biotechnology, and BioInstitute, Korea University, Seoul 136-701, Republic of Korea.

It has been reported that ribosomal protein S3 (rpS3) functions as a ribosomal protein, a DNA repair endonuclease, a proapoptotic protein, and an essential subunit of the native NF-κB complex. However, it is unknown how rpS3 induces apoptosis in response to extracellular stresses. We report here that rpS3 sensitizes genotoxic stress-induced apoptosis by activating JNK through a caspase dependent manner. This apoptotic effect was shown to result from the physical interaction between rpS3 and TRADD, as assessed by coimmunoprecipitation. Moreover, GFP-rpS3 colocalized with TRADD around the plasma membrane and in the cytoplasm during apoptosis. Thus, rpS3 appears to be recruited to the death-inducing signaling complex (DISC) to induce apoptosis by interacting TRADD in response to extracellular stresses. Based on the findings of this study, we concluded that rpS3 is recruited to the DISC and plays a critical role in both genotoxic stress and cytokine induced apoptosis.
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http://dx.doi.org/10.1016/j.bbrc.2012.04.020DOI Listing
May 2012

Ribosomal protein S3 is stabilized by sumoylation.

Biochem Biophys Res Commun 2011 Oct 24;414(3):523-7. Epub 2011 Sep 24.

Laboratory of Biochemistry, School of Life Sciences and Biotechnology, and BioInstitute, Korea University, Seoul 136-701, Republic of Korea.

Human ribosomal protein S3 (rpS3) acts as a DNA repair endonuclease. The multiple functions of this protein are regulated by post-translational modifications including phosphorylation and methylation. Using a yeast-two hybrid screen, we identified small ubiquitin-related modifier-1 (SUMO-1) as a new interacting partner of rpS3. rpS3 interacted with SUMO-1 via the N- and C-terminal regions. We also observed sumoylation of rpS3 in Escherichia coli and mammalian cell systems. Furthermore, we discovered that one of three lysine residues, Lys18, Lys214, or Lys230, was sumoylated in rpS3. Interestingly, sumoylated rpS3 was resistant to proteolytic activity, indicating that SUMO-1 increased the stability of the rpS3 protein. We concluded that rpS3 is covalently modified by SUMO-1 and this post-translational modification regulates rpS3 function by increasing rpS3 protein stability.
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http://dx.doi.org/10.1016/j.bbrc.2011.09.099DOI Listing
October 2011

Mitotic kinases regulate MT-polymerizing/MT-bundling activity of DDA3.

Biochem Biophys Res Commun 2011 Apr 5;408(1):174-9. Epub 2011 Apr 5.

Department of Biological Sciences, Stanford University, Stanford, CA 94305-5020, USA.

Mitotic kinases orchestrate cell cycle processes by phosphorylation of cell cycle regulators. DDA3, a spindle-associated phosphor-protein, is a substrate of mitotic kinases that control chromosome movement and spindle microtubule (MT) dynamics. Through a mass spectrometry analysis, we identified phosphorylation sites on the endogenous mitotic DDA3, which include Ser22, Ser65, Ser70, and Ser223. Phosphorylation of these residues converts interphase form of DDA3 to mitotic form by changing its biochemical activity, as unphosphorylated DDA3 processed both the MT polymerizing and bundling activities, whereas phosphor-mimic mutants lost both activities, only retaining the MT-binding activity. We found that mitotic kinases, such as Cdk1, Aurora A, and Plk1, phosphorylate DDA3 in vitro. Whereas Cdk1 and Aurora A negatively regulate MT-polymerizing and MT-bundling activities, Plk1 does not affect these activities. Interestingly, the phosphorylation of DDA3 by Aurora A and Plk1 inhibits the phosphorylation by other kinases, indicating that sequential phosphorylation is important for the regulation of DDA3 function. We conclude that kinases control the function of DDA3 in the cell cycle by regulating its MT-polymerizing/bundling activities through sequential phosphorylation.
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http://dx.doi.org/10.1016/j.bbrc.2011.04.004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7055931PMC
April 2011

DDA3 associates with MCAK and controls chromosome congression.

Biochem Biophys Res Commun 2011 Apr 21;407(3):610-4. Epub 2011 Mar 21.

School of Pharmacy, Sookmyung Women's University, Seoul 140-742, Republic of Korea.

DDA3 regulates spindle microtubule (MT) dynamics and chromosome movement in mitosis through its interaction with and subsequent recruitment of Kif2a, a minus end-MT depolymerase. Depletion of DDA3 causes a hyper-stabilization of spindle MT, a loss of inter-kinetochore tension, and a defect in chromosome congression, leading to unaligned chromosomes at metaphase. We report here that DDA3 is also localized at kinetochores and interacts with MCAK. Furthermore, CENP-E, a plus end-motor protein, accumulates at kinetochores in unaligned chromosomes in mitotic cells depleted of DDA3. On the other hand, the localization of chromosomal passenger complex (CPC) and the kinase activity of Aurora B are normal in DDA3-depleted cells. We conclude that MCAK and CENP-E are involved in DDA3-mediated chromosome congression.
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http://dx.doi.org/10.1016/j.bbrc.2011.03.081DOI Listing
April 2011