Hyo-Joon Kim
Hanyang University
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Publication
Featured researches published by Hyo-Joon Kim.
Oncogene | 2007
Dong-Hyung Cho; Hyo-Jong Lee; Hyo-Joon Kim; Sunghee Hong; Jong-Ok Pyo; Chunghee Cho; Yong-Keun Jung
Apaf-1-interacting protein (APIP) was previously isolated as an inhibitor of mitochondrial cell death interacting with Apaf-1. Here, we report a hypoxia-selective antiapoptotic activity of APIP that induces the activation of AKT and extracellular signal-regulated kinase (ERK)1/2. Stable expression of APIP in C2C12 (C2C12/APIP) cells suppressed cell death induced by hypoxia and etoposide. Unlike etoposide, however, APIP induces the sustained activation of AKT and ERK1/2 and the phosphorylation of caspase-9 during hypoxia. Inhibition of AKT and ERK1/2 activation by the treatments with phosphatidylinositol 3′-kinase and mitogen-activated protein kinase kinase (MEK)1/2 inhibitors sensitized C2C12/APIP cells to hypoxic cell death and abolished the hypoxia-induced phosphorylation of caspase-9. Further, overexpression of phosphorylation-mimic caspase-9 mutants (caspase-9-T125E and caspase-9-S196D), but not phosphorylation-defective caspase-9 mutants (caspase-9-T125A and caspase-9-S196A), effectively suppressed hypoxia-induced death of C2C12 cells. These results elucidate a novel Apaf-1-independent antiapoptotic activity of APIP during hypoxic cell death, inducing the sustained activation of AKT and ERK1/2 and leading to caspase-9 phosphorylation.
Journal of Biological Chemistry | 2008
Jong-Ok Pyo; Jihoon Nah; Hyojin Kim; Jae Woong Chang; Young-Wha Song; Dong-Kwon Yang; Dong-Gyu Jo; Hyung-Ryong Kim; Han-Jung Chae; Soo-Wan Chae; Seung-Yong Hwang; Seung Jun Kim; Hyo-Joon Kim; Chunghee Cho; Chang-Gyu Oh; Woo Jin Park; Yong-Keun Jung
The ischemic death of cardiomyocytes is associated in heart disease and heart failure. However, the molecular mechanism underlying ischemic cell death is not well defined. To examine the function of apoptosis repressor with a caspase recruitment domain (ARC) in the ischemic/hypoxic damage of cardiomyocytes, we generated cardio-specific ARC transgenic mice using a mouse α-myosin heavy chain promoter. Compared with the control, the hearts of ARC transgenic mice showed a 3-fold overexpression of ARC. Langendoff preparation showed that the hearts isolated from ARC transgenic mice exhibited improved recovery of contractile performance during reperfusion. The cardiomyocytes cultured from neonatal ARC transgenic mice were significantly resistant to hypoxic cell death. Furthermore, the ARC C-terminal calcium-binding domain was as potent to protect cardiomyocytes from hypoxic cell death as ARC. Genome-wide RNA expression profiling uncovered a list of genes whose expression was changed (>2-fold) in ARC transgenic mice. Among them, expressional regulation of developmentally regulated RNA-binding protein 1 (Drbp1) or the dimethylglycine dehydrogenase precursor (pMe2GlyDH) affected hypoxic death of cardiomyocytes. These results suggest that ARC may protect cardiomyocytes from hypoxic cell death by regulating its downstream, Drbp1 and pMe2GlyDH, shedding new insights into the protection of heart from hypoxic damages.
Oncogene | 2008
Young Jun Jeon; In-Ki Kim; Sunghee Hong; Nan H; Hyo-Joon Kim; Hyo-Jong Lee; Masuda Es; Meyuhas O; Byung-Ha Oh; Yong-Keun Jung
TRAIL (tumor necrosis factor-related apoptosis-inducing ligand) is a potent inducer of apoptosis in tumor cells and holds a promise as a therapeutic agent against cancer. To elucidate the death signaling evoked by TRAIL, we performed a functional genetic screening and rescued TRAIL-resistant Jurkat clones harboring ribosomal protein S6 (rpS6) cDNA in anti-sense frame. Reduction of rpS6 expression in Jurkat and HeLa cells attenuated apoptosis induced by TRAIL, but not those by other cell death signals, including tumor necrosis factor-α and cycloheximide, etoposide, doxorubicin, tunicamycin and staurosporine. Death receptor (DR) 4, but not DR5, was downregulated in rpS6 knockdown cells. Conversely, the sensitivity to TRAIL was increased by the ectopic expression of wild-type rpS6 and further by phospho-defective rpS6 mutant (S6-SS235,6AA), but not by phospho-mimic rpS6 mutant (S6-SS235,6DD). Also, unphosphorylatable rpS6 knock-in mouse embryo fibroblasts (rpS6P−/− MEFs) were more sensitive to TRAIL than control MEFs. In addition, SKHep-1 tumor cells, which express less phospho-rpS6 and are more sensitive to TRAIL than other tumor cells, became effectively desensitized to TRAIL after rpS6 knockdown. These results suggest that rpS6, especially in its unphosphorylated form, is a selective mediator of TRAIL-induced apoptosis.
Oncogene | 2015
Hyo-Joon Kim; Sun Hee Kim; Eun Ji Yu; Woo-Young Seo; Ju Hyun Kim
Deleted in Breast Cancer 1 (DBC1), a negative regulator of deacetylase SIRT1, has been shown to act as an estrogen receptor α (ER) coactivator that has a key role in ER transcription complex assembly and estrogen-dependent breast cancer cell proliferation. However, little is known about its physiological role and mechanism of action in ER-negative breast cancer cells. Here we report that DBC1 functions as a coactivator for the oncogenic ETS transcription factor PEA3 to promote ER-negative breast cancer progression. DBC1 is required for the expression of PEA3 target genes and for recruitment of PEA3 and RNA polymerase II to PEA3 target promoters. We also demonstrated that acetylation of PEA3 stimulates its DNA binding and association with DBC1 by disrupting the intramolecular interaction of PEA3. The molecular mechanism underlying DBC1 function in PEA3-mediated transcription involves inhibition of SIRT1 interaction with PEA3 and of SIRT1-mediated deacetylation of PEA3. Moreover, DBC1 depletion inhibited the tumorigenic properties of ER-negative breast cancer cells in vitro and in vivo. Importantly, increased DBC1 expression correlated with shorter relapse-free survival of ER-negative breast cancer patients. Our results firmly established DBC1 as a critical coactivator of PEA3 and as a key player in PEA3-mediated breast cancer progression.
Optics Letters | 2012
Hyo-Joon Kim; Ohung Kwon; Sang Bae Lee; Young-Guen Han
Transmission characteristics of polarization-dependent refractometer based on a surface long-period grating (SLPG) inscribed in a D-shaped photonic crystal fiber (PCF) are investigated. The birefringence of SLPG produces the separation of transmission spectra for TE and TM polarization modes. We also measure the sensitivities of PCF-based SLPG to temperature and external refractive index change depending on the input polarization states. The SLPG-based sensor exhibits different temperature and ambient index sensitivities corresponding to TE and TM polarization modes. Therefore, the SLPG inscribed in D-shaped PCFs can effectively discriminate temperature and ambient index sensitivities.
Oncogene | 2016
Eun Ji Yu; Sun Hee Kim; Hyo-Joon Kim; Kyu Heo; Ou Cy; Michael R. Stallcup; Ju Hyun Kim
Aberrant activation of Wnt/β-catenin pathway contributes to colorectal cancer (CRC) progression. However, little is known about regulatory mechanisms of the β-catenin activity in cancer progression. Here we investigated the role of DBC1, which was recently reported as a negative regulator of SIRT1 and a transcriptional coactivator, in the regulation of Wnt/β-catenin signaling. We identified the genome-wide targets of DBC1 and found that loss of DBC1 inhibits the expression of β-catenin target genes including PROX1, a transcription factor linked to CRC progression. Mechanistically, DBC1 stabilizes LEF1–β-catenin interaction by inhibiting SIRT1-mediated β-catenin deacetylation, thereby enhancing LEF1–β-catenin complex formation and long-range chromatin looping at the PROX1 locus. Furthermore, DBC1 is also required for the transcriptional activity of PROX1, suggesting that DBC1 has a dual function in regulating β-catenin–PROX1 signaling axis: as a coactivator for both β-catenin and PROX1. Importantly, loss of DBC1 inhibited growth and tumorigenic potential of colon cancer cells, and DBC1 expression correlated with shorter relapse-free survival in patients with advanced CRC. Our results firmly establish DBC1 as a critical positive regulator of β-catenin–PROX1 signaling axis and a key factor in β-catenin–PROX1-mediated CRC progression.
Environmental Toxicology and Pharmacology | 2005
Jung-Ran Kim; Hyo-Joon Kim; Oh-Seung Kwon
An organophosphate pesticide terbufos (S-t-butylthiomethyl-O,O-diethyl phosphorodithioate; TBF) has been extensively used as an insecticide. A sexual dimorphism in TBF toxicity was not reported and remains unclear. The objective of the work was to investigate the influence of TBF on sexual dimorphism after oral administration of TBF to rats by using acetylcholinesterase (AChE) and neuropathy target esterase (NTE) as endpoints. TBF was orally administered to Sprague-Dawley rats, where female rats were received 0, 0.1, 0.4 and 0.8mg/kg TBF for 2 days and male rats 0, 0.1, 0.5 and 1.0mg/kg TBF for 3 days for dose-dependent study. Age-matched female and male rats also received equally 0.5mg/kg TBF for 2 days and sacrificed 0, 6, 12, 24 and 72h after the last dose for time-dependent study. In the dose-dependent study, mortality was 25% in 1.0mg/kg TBF group of male and 50% in 0.4 and 0.8mg/kg TBF groups of female rats, resulting in about two-fold higher in female than male. AChE was significantly decreased only in the frontal and entorhinal cortexes of female rats receiving 0.4 or 0.8mg/kg TBF. In the time-dependent study, the maximal inhibition in the brain regions or plasma was two- or three-fold higher in female, which occurred 6 or 12h after the last dose. However, effects of TBF on alteration of NTE activity were minor, compared to AChE, indicating that AChE is more sensitive marker than NTE in TBF toxicity. These results also indicate that female was more vulnerable to AChE inhibition than male rats after exposure to TBF.
Journal of Biochemistry and Molecular Biology | 1999
Yong-Seek Park; Myung-Hoon Cha; Whan-Mi Yong; Hyo-Joon Kim; Il-Yup Chung; Young-Seek Lee
Tuberculosis and Respiratory Diseases | 2006
Seung-Heon Lee; Hyo-Joon Kim; Young-Kil Park; Gill-Han Bai
Journal of Biochemistry and Molecular Biology | 1999
Hyo-Joon Kim; Yang-Min Lee; Joonsung Hwang; Hoshik Won; Bok-Hwan Kim