Publications by authors named "Sung-Gyoo Park"

68 Publications

Integrated Quantitative Phosphoproteomics and Cell-based Functional Screening Reveals Specific Pathological Cardiac Hypertrophy-related Phosphorylation Sites.

Mol Cells 2021 Jul;44(7):500-516

School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Korea.

Cardiac hypertrophic signaling cascades resulting in heart failure diseases are mediated by protein phosphorylation. Recent developments in mass spectrometry-based phosphoproteomics have led to the identification of thousands of differentially phosphorylated proteins and their phosphorylation sites. However, functional studies of these differentially phosphorylated proteins have not been conducted in a large-scale or high-throughput manner due to a lack of methods capable of revealing the functional relevance of each phosphorylation site. In this study, an integrated approach combining quantitative phosphoproteomics and cell-based functional screening using phosphorylation competition peptides was developed. A pathological cardiac hypertrophy model, junctate-1 transgenic mice and control mice, were analyzed using label-free quantitative phosphoproteomics to identify differentially phosphorylated proteins and sites. A cell-based functional assay system measuring hypertrophic cell growth of neonatal rat ventricle cardiomyocytes (NRVMs) following phenylephrine treatment was applied, and changes in phosphorylation of individual differentially phosphorylated sites were induced by incorporation of phosphorylation competition peptides conjugated with cell-penetrating peptides. Cell-based functional screening against 18 selected phosphorylation sites identified three phosphorylation sites (Ser-98, Ser-179 of Ldb3, and Ser-1146 of palladin) displaying near-complete inhibition of cardiac hypertrophic growth of NRVMs. Changes in phosphorylation levels of Ser-98 and Ser-179 in Ldb3 were further confirmed in NRVMs and other pathological/physiological hypertrophy models, including transverse aortic constriction and swimming models, using site-specific phospho-antibodies. Our integrated approach can be used to identify functionally important phosphorylation sites among differentially phosphorylated sites, and unlike conventional approaches, it is easily applicable for large-scale and/or high-throughput analyses.
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http://dx.doi.org/10.14348/molcells.2021.4002DOI Listing
July 2021

Discovery of Novel Pyrimidine-Based Capsid Assembly Modulators as Potent Anti-HBV Agents.

J Med Chem 2021 05 22;64(9):5500-5518. Epub 2021 Apr 22.

School of Life Science, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Republic of Korea.

Core assembly modulators of viral capsid proteins have been developed as an effective treatment of chronic hepatitis B virus (HBV) infection. In this study, we synthesized novel potent pyrimidine derivatives as core assembly modulators, and their antiviral effects were evaluated in in vitro and in vivo biological experiments. One of the synthesized derivatives, compound (R = MeSO, R = 1-piperidin-4-amine, R = 3-Cl-4-F-aniline) displayed potent inhibitory effects in the in vitro assays (52% inhibition in the protein-based assay at 100 nM and an IC value of 181 nM in the serum HBV DNA quantification assay). Moreover, treatment with compound for 5 weeks significantly decreased serum levels of HBV DNA levels (3.35 log reduction) in a human liver-chimeric uPA/SCID mouse model, and these effects were significantly increased when was combined with tenofovir, a nucleotide analogue inhibitor of reverse transcriptase used for the treatment of HBV infection.
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http://dx.doi.org/10.1021/acs.jmedchem.0c01938DOI Listing
May 2021

ZIP8 exacerbates collagen-induced arthritis by increasing pathogenic T cell responses.

Exp Mol Med 2021 Apr 1;53(4):560-571. Epub 2021 Apr 1.

School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju, 61005, Republic of Korea.

Zinc is a trace element that is essential for immune responses. Therefore, changes in cellular zinc levels in specific immune cells may influence inflammatory autoimmune diseases, such as rheumatoid arthritis (RA). However, the regulation of zinc mobilization in immune cells and its role in the pathogenesis of RA are not fully understood. Thus, we investigated the roles of zinc transporters in RA pathogenesis. We demonstrated that ZIP8 was specifically upregulated in CD4 T cells that infiltrated the inflamed joint and that ZIP8 deficiency in CD4 T cells abrogated collagen-induced arthritis. ZIP8 deficiency dramatically affected zinc influx in effector T cells and profoundly reduced T cell receptor (TCR)-mediated signaling, including NF-κB and MAPK signaling, which are pathways that are involved in T helper (Th) 17 cell differentiation. Taken together, our findings suggest that ZIP8 depletion in CD4 T cells attenuates TCR signaling due to insufficient cellular zinc, thereby reducing the function of effector CD4 T cells, including Th17 cells. Our results also suggest that targeting ZIP8 may be a useful strategy to inhibit RA development and pathogenesis.
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http://dx.doi.org/10.1038/s12276-021-00591-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8102558PMC
April 2021

PDK1 Is Required for Maintenance of CD4 Foxp3 Regulatory T Cell Function.

J Immunol 2021 Apr 31;206(8):1776-1783. Epub 2021 Mar 31.

Department of Microbiology and Immunology, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, NY 10032;

Regulatory T (Treg) cells have an essential role in maintaining immune homeostasis, in part by suppressing effector T cell functions. Phosphoinositide-dependent kinase 1 (PDK1) is a pleiotropic kinase that acts as a key effector downstream of PI3K in many cell types. In T cells, PDK1 has been shown to be critical for activation of NF-κB and AKT signaling upon TCR ligation and is therefore essential for effector T cell activation, proliferation, and cytokine production. Using Treg cell-specific conditional deletion, we now demonstrate that PDK1 is also essential for Treg cell suppressive activity in vivo. Ablation of specifically in Treg cells led to systemic, lethal, -like inflammation in mice. Genome-wide analysis confirmed that PDK1 is essential for the regulation of key Treg cell signature gene expression and, further, suggested that PDK1 acts primarily to control Treg cell gene expression through regulation of the canonical NF-κB pathway. Consistent with these results, the like phenotype of mice lacking PDK1 in Treg cells was rescued by enforced activation of NF-κB downstream of PDK1. Therefore, PDK1-mediated activation of the NF-κB signaling pathway is essential for regulation of Treg cell signature gene expression and suppressor function.
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http://dx.doi.org/10.4049/jimmunol.2000051DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8026672PMC
April 2021

The Functional Roles and Applications of Immunoglobulins in Neurodegenerative Disease.

Int J Mol Sci 2020 Jul 26;21(15). Epub 2020 Jul 26.

School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Korea.

Natural autoantibodies, immunoglobulins (Igs) that target self-proteins, are common in the plasma of healthy individuals; some of the autoantibodies play pathogenic roles in systemic or tissue-specific autoimmune diseases, such as rheumatoid arthritis and systemic lupus erythematosus. Recently, the field of autoantibody-associated diseases has expanded to encompass neurodegenerative diseases such as Alzheimer's disease (AD) and Parkinson's disease (PD), with related studies examining the functions of Igs in the central nervous system (CNS). Recent evidence suggests that Igs have various effects in the CNS; these effects are associated with the prevention of neurodegeneration, as well as induction. Here, we summarize the functional roles of Igs with respect to neurodegenerative disease (AD and PD), focusing on the target antigens and effector cell types. In addition, we review the current knowledge about the roles of these antibodies as diagnostic markers and immunotherapies.
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http://dx.doi.org/10.3390/ijms21155295DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7432158PMC
July 2020

Recent insights of T cell receptor-mediated signaling pathways for T cell activation and development.

Exp Mol Med 2020 05 21;52(5):750-761. Epub 2020 May 21.

School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju, 61005, Korea.

T cell activation requires extracellular stimulatory signals that are mainly mediated by T cell receptor (TCR) complexes. The TCR recognizes antigens on major histocompatibility complex molecules with the cooperation of CD4 or CD8 coreceptors. After recognition, TCR-induced signaling cascades that propagate signals via various molecules and second messengers are induced. Consequently, many features of T cell-mediated immune responses are determined by these intracellular signaling cascades. Furthermore, differences in the magnitude of TCR signaling direct T cells toward distinct effector linages. Therefore, stringent regulation of T cell activation is crucial for T cell homeostasis and proper immune responses. Dysregulation of TCR signaling can result in anergy or autoimmunity. In this review, we summarize current knowledge on the pathways that govern how the TCR complex transmits signals into cells and the roles of effector molecules that are involved in these pathways.
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http://dx.doi.org/10.1038/s12276-020-0435-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7272404PMC
May 2020

Comparison of Two Analytical Platforms in Cerebrospinal Fluid Biomarkers for the Classification of Alzheimer's Disease Spectrum with Amyloid PET Imaging.

J Alzheimers Dis 2020 ;75(3):949-958

Department of Biomedical Science, Chosun University, Gwangju, Republic of Korea.

Background: Cerebrospinal fluid (CSF) amyloid-β1-42 (Aβ1-42), total tau protein (t-Tau), and phosphorylated Tau (p-Tau) are ATN biomarkers for Alzheimer's disease (AD) and reflect pathogenic changes in the brain. CSF biomarkers of AD are considered for inclusion in the diagnostic criteria for research and clinical purposes to reduce the uncertainty of clinical diagnosis and to distinguish among AD stages.

Objective: This study aims to compare two commercially available analytical platforms with respect to accuracy and the potential for early diagnosis of AD.

Methods: A total of 211 CSF samples from healthy control (HC) and AD subjects were analyzed using two analytical platforms, INNOTEST ELISA and INNOBIA AlzBio3 xMAP kits. The accuracy of diagnosis and AUC values distinguishing study groups were compared between the two analytical platforms.

Results: The absolute values for Aβ1-42, t-Tau, and p-Tau181 levels differed between the two platforms. The Aβ1-42 levels decreased, while t-Tau and p-Tau levels increased according to the AD stages. The AUC of Aβ1-42 and t-Tau, which distinguish the early stages of AD (preclinical and prodromal AD), were similar between the two platforms, whereas there were significant differences in p-Tau AUC values. CSF p-Tau using the INNOBIA was highly accurate for distinguishing both preclinical AD (AUC = 0.826, cut-off score≥38.89) and prodromal AD (AUC = 0.862, cut-off score≥41.88) from HC.

Conclusion: The accuracy of CSF p-Tau levels in the preclinical and prodromal AD is higher for the INNOBIA than the INNOTEST, and the early stage AD can be accurately distinguished from HC.
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http://dx.doi.org/10.3233/JAD-191331DOI Listing
May 2021

Development of a mass spectrometric screening assay for hepatitis B virus entry inhibitors.

J Pharm Biomed Anal 2020 Jan 3;178:112959. Epub 2019 Nov 3.

Department of Chemistry, School of Physics and Chemistry, Gwangju Institute of Science and Technology, Gwangju, 61005, South Korea; School of Earth Sciences and Environmental Engineering, Gwangju Institute of Science and Technology, Gwangju, 61005, South Korea. Electronic address:

Sodium taurocholate cotransporting polypeptide (NTCP) involved in bile acid transport in the liver is an entry receptor of hepatitis B virus (HBV). In the present study, we introduce a mass spectrometric screening assay for targeting HBV entry inhibitors that can reduce NTCP transporter activity by employing taurocholic acid (TCA) labeled with stable isotope (2,2,4,4-d-TCA, d-TCA) and NTCP-overexpressing human liver cancer cell lines such as HepG2 and Huh-7. The accuracy and reliability of the proposed mass spectrometric NTCP activity assay have been validated with known HBV inhibitors including cyclosporine A (CsA) and pre-S1 peptide (PreS/2-48 or myrcludex B analog) that suppress the entry of HBV into hepatocytes by targeting NTCP. For the inhibitor screening assay, NTCP-overexpressing HepG2 or Huh-7 cells are treated with either a combination of TCA and an inhibitor (CsA or PreS/2-48) or d-TCA alone to serve as a reference. The activity of an HBV inhibitor is determined by relative quantification between TCA and d-TCA in a 1:1 mixture of inhibitor-treated cells and untreated control cells using liquid chromatography-mass spectrometry. With our new approach, the half maximal inhibitory concentration (IC) values for CsA and PreS/2-48 have been determined at micromolar and nanomolar concentrations, respectively, which is consistent with the previous results obtained with other conventional HBV entry inhibitor assay methods. Our assay method does not require HBV infection or radioactive H-TCA and provides a facile way to identify viral entry inhibitors via measuring bile acid transport activity of NTCP.
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http://dx.doi.org/10.1016/j.jpba.2019.112959DOI Listing
January 2020

A Case of Familial Spondyloenchondrodysplasia with Immune Dysregulation Masquerading as Moyamoya Syndrome.

J Clin Neurol 2019 Jul;15(3):407-409

Department of Pediatrics, Pediatric Clinical Neuroscience Center, Seoul National University Children's Hospital, Seoul National University College of Medicine, Seoul, Korea.

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http://dx.doi.org/10.3988/jcn.2019.15.3.407DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6620444PMC
July 2019

SERPINA3 is a key modulator of HNRNP-K transcriptional activity against oxidative stress in HCC.

Redox Biol 2019 06 12;24:101217. Epub 2019 May 12.

Department of Biological Sciences, College of Natural Sciences, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul, 08826, Republic of Korea. Electronic address:

Most studies about serpin peptidase inhibitor, clade A member 3 (SERPINA3) has been limited to its inhibitory functions and mechanisms. Herein, we report a novel role of SERPINA3 in transcriptional regulation of HCC progression-related genes. Among 19 selected genes through HCC cell isolation system based on telomere length, microarray analyses, and cell-based studies, SERPINA3 was the strongest determinant of increases in telomere length, HCC cell proliferation, survival, migration, and invasion. We also found that SERPINA3 strongly interacted with heterogeneous nuclear ribonucleoprotein K (HNRNP-K) under HO exposure, and the oxidation-elicited SERPINA3-HNRNP-K complex enhanced the promoter activities and transcript levels of a telomere-relating gene (POT1) and HCC-promoting genes (UHRF1 and HIST2H2BE). Intriguingly, the inhibition of SERPINA3 oxidation rendered the transcriptional activity of the SERPINA3-HNRNP-K complex suppressed. Moreover, the co-immunoprecipitated HNRNP-K with SERPINA3 quantitatively correlated with not only the level of SERPINA3 oxidation but also the level of POT1, UHRF1, and HIST2H2BE transcripts and telomere length in HCC tissues. Therefore, the upregulated transcriptional activity of HNRNP-K mediated by SERPINA3 promotes HCC cell survival and proliferation and could be an indicator of poor prognosis for HCC patients.
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http://dx.doi.org/10.1016/j.redox.2019.101217DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6529774PMC
June 2019

Ciclopirox inhibits Hepatitis B Virus secretion by blocking capsid assembly.

Nat Commun 2019 05 16;10(1):2184. Epub 2019 May 16.

School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju, 61005, Republic of Korea.

Chronic hepatitis B virus (HBV) infection can cause cirrhosis and hepatocellular carcinoma and is therefore a serious public health problem. Infected patients are currently treated with nucleoside/nucleotide analogs and interferon α, but this approach is not curative. Here, we screen 978 FDA-approved compounds for their ability to inhibit HBV replication in HBV-expressing HepG2.2.15 cells. We find that ciclopirox, a synthetic antifungal agent, strongly inhibits HBV replication in cells and in mice by blocking HBV capsid assembly. The crystal structure of the HBV core protein and ciclopirox complex reveals a unique binding mode at dimer-dimer interfaces. Ciclopirox synergizes with nucleoside/nucleotide analogs to prevent HBV replication in cells and in a humanized liver mouse model. Therefore, orally-administered ciclopirox may provide a novel opportunity to combat chronic HBV infection by blocking HBV capsid assembly.
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http://dx.doi.org/10.1038/s41467-019-10200-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6522524PMC
May 2019

Cerebrospinal Fluid Biomarkers for the Diagnosis of Prodromal Alzheimer's Disease in Amnestic Mild Cognitive Impairment.

Dement Geriatr Cogn Dis Extra 2019 Jan-Apr;9(1):100-113. Epub 2019 Mar 12.

Department of Biomedical Science, Chosun University, Gwangju, Republic of Korea.

Background/aims: Disease-modifying therapy for Alzheimer's disease (AD) has led to a need for biomarkers to identify prodromal AD and very early stage of AD dementia. We aimed to identify the cutoff values of cerebrospinal fluid (CSF) biomarkers for detecting prodromal AD.

Methods: We assessed 56 patients with amnestic mild cognitive impairment (aMCI) who underwent lumbar puncture. Additionally, 87 healthy elderly individuals and 34 patients with AD dementia served as controls. Positron emission tomography was performed using florbetaben as a probe. We analyzed the concentration of Aβ, total tau protein (t-Tau), and tau protein phosphorylated at threonine 181 (p-Tau) in CSF with INNOTEST enzyme-linked immunosorbent assay.

Results: For the detection of prodromal AD in patients with aMCI, the cutoff values of CSF Aβ, t-Tau, and p-Tau were 749.5 pg/mL, 225.6 pg/mL, and 43.5 pg/mL, respectively. To discriminate prodromal AD in patients with aMCI, the t-Tau/Aβ and -p-Tau/Aβ ratios defined cutoff values at 0.298 and 0.059, respectively.

Conclusions: CSF biomarkers are very useful tools for the differential diagnosis of prodromal AD in aMCI patients. The concentration of CSF biomarkers is well correlated with the stages of the AD spectrum.
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http://dx.doi.org/10.1159/000496920DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6465729PMC
March 2019

Phosphorylation of p53 Serine 15 Is a Predictor of Survival for Patients with Hepatocellular Carcinoma.

Can J Gastroenterol Hepatol 2019 7;2019:9015453. Epub 2019 Feb 7.

School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 61005, Republic of Korea.

Background: Hepatocellular carcinoma (HCC) is one of the most common malignant cancers with a poor prognosis. Several commonly investigated immunohistochemical markers in resected HCC have potential prognostic value, but the prognostic utility of p53 expression in HCC has remained elusive.

Aim: To evaluate the prognostic value of p53 and p53 phosphorylation at serine 15 (p53 Ser15-P) in patients with HCC.

Methods: Surgically resected tumors from 199 HCC patients were analyzed for p21, p53, p53 Ser15-P, and proliferating cell nuclear antigen (PCNA) expression using immunohistochemistry.

Results: Stratifying by the expression of p53 Ser15-P ( = 0.016), but not by p53 ( = 0.301), revealed significantly different survival outcomes in patients with HCC. Moreover, our analysis demonstrated that patients who were PCNA-positive and p53 Ser15-P-negative had significantly worse survival outcomes ( = 0.001) than patients who were PCNA-positive and p53 Ser15-P-positive.

Conclusions: P53 Ser15-P is associated with poor outcomes in patients with HCC, and this prognostic marker is useful for predicting the survival of patients with PCNA-positive HCC.
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http://dx.doi.org/10.1155/2019/9015453DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6383407PMC
August 2019

High-throughput epitope profiling of antibodies in the plasma of Alzheimer's disease patients using random peptide microarrays.

Sci Rep 2019 03 14;9(1):4587. Epub 2019 Mar 14.

School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju, Republic of Korea.

The symptoms of Alzheimer's disease (AD), a major cause of dementia in older adults, are linked directly with neuronal cell death, which is thought to be due to aberrant neuronal inflammation. Autoantibodies formed during neuronal inflammation show excellent stability in blood; therefore, they may be convenient blood-based diagnostic markers of AD. Here, we performed microarray analysis of 29,240 unbiased random peptides to be used for comprehensive screening of AD-specific IgG and IgM antibodies in the blood. The results showed that (1) sequence-specific and isotype-specific antibodies are regulated differentially in AD, and combinations of these antibodies showing high area under the receiver operating characteristic curve values (0.862-0.961) can be used to classify AD, (2) AD-specific IgG antibodies arise from IgM antibody-secreting cells that existed before disease onset and (3) target protein profiling of the antibodies identified some AD-related proteins, some of which are involved in AD-related signalling pathways. Therefore, we propose that these epitopes may facilitate the development of biomarkers for AD diagnosis and form the basis for a mechanistic study related to AD progression.
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http://dx.doi.org/10.1038/s41598-019-40976-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6418098PMC
March 2019

Mouse models for hepatitis B virus research.

Lab Anim Res 2018 Sep 27;34(3):85-91. Epub 2018 Sep 27.

School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju, Korea.

Hepatitis B virus (HBV) infection remains a major global health problem; indeed, there are 250 million carriers worldwide. The host range of HBV is narrow; therefore, few primates are susceptible to HBV infection. However, ethical constraints, high cost, and large size limit the use of primates as suitable animal models. Thus, testing of therapies that target HBV has been hampered by the lack of an appropriate research model. To address this, mouse model systems of HBV are being developed and several are used for studying HBV . In this review, we summarize the currently available mouse models, including HBV transgenic mice, hydrodynamic injection-mediated HBV replicon delivery systems, adeno-associated virus-mediated HBV replicon delivery systems, and human liver chimeric mouse models. These developed (or being developed) mouse model systems are promising and should be useful tools for studying HBV.
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http://dx.doi.org/10.5625/lar.2018.34.3.85DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6170223PMC
September 2018

Murine γδ T Cells Render B Cells Refractory to Commitment of IgA Isotype Switching.

Immune Netw 2018 Aug 13;18(4):e25. Epub 2018 Aug 13.

Department of Molecular Bioscience, College of Biomedical Science and Institute of Bioscience and Biotechnology, Kangwon National University, Chuncheon 24341, Korea.

γδ T cells are abundant in the gut mucosa and play an important role in adaptive immunity as well as innate immunity. Although γδ T cells are supposed to be associated with the enhancement of Ab production, the status of γδ T cells, particularly in the synthesis of IgA isotype, remains unclear. We compared Ig expression in T cell receptor delta chain deficient (TCRδ) mice with wild-type mice. The amount of IgA in fecal pellets was substantially elevated in TCRδ mice. This was paralleled by an increase in surface IgA expression and total IgA production by Peyer's patches (PPs) and mesenteric lymph node (MLN) cells. Likewise, the TCRδ mice produced much higher levels of serum IgA isotype. Here, surface IgA expression and number of IgA secreting cells were also elevated in the culture of spleen and bone marrow (BM) B cells. Germ-line α transcript, an indicator of IgA class switch recombination, higher in PP and MLN B cells from TCRδ mice, while it was not seen in inactivated B cells. Nevertheless, the frequency of IgA B cells was much higher in the spleen from TCRδ mice. These results suggest that γδ T cells control the early phase of B cells, in order to prevent unnecessary IgA isotype switching. Furthermore, this regulatory role of γδ T cells had lasting effects on the long-lived IgA-producing plasma cells in the BM.
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http://dx.doi.org/10.4110/in.2018.18.e25DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6117511PMC
August 2018

BATF regulates collagen-induced arthritis by regulating T helper cell differentiation.

Arthritis Res Ther 2018 08 2;20(1):161. Epub 2018 Aug 2.

School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju, 61005, Republic of Korea.

Background: We recently demonstrated that BATF, a member of the activator protein-1 (AP-1) family, regulates osteoarthritic cartilage destruction. Here, we explored the roles and regulatory mechanisms of BATF in collagen-induced arthritis (CIA) in mice.

Methods: CIA and K/BxN serum transfer were used to generate inflammatory arthritis models in wild-type (WT) and Batf mice. RA manifestations were determined by examining CIA incidence, clinical score, synovitis, synovial hyperplasia, angiogenesis in inflamed synovium, pannus formation, bone erosion, and cartilage destruction. Immune features in RA were analyzed by examining immune cell populations and cytokine production.

Results: BATF was upregulated in the synovial tissues of joints in which inflammatory arthritis had been caused by CIA or K/BxN serum transfer. The increases in CIA incidence, clinical score, and autoantibody production in CIA-induced WT mice were completely abrogated in the corresponding Batf DBA/1 J mice. Genetic ablation of Batf also inhibited CIA-induced synovitis, synovial hyperplasia, angiogenesis in synovial tissues, pannus formation, bone erosion, and cartilage destruction. Batf knockout inhibited the differentiation of T helper (Th)17 cells and the conversion of CD4Foxp3 cells to CD4IL-17 cells. However, BATF did not modulate the functions of fibroblast-like synoviocytes (FLS), including the expressions of chemokines, matrix-degrading enzymes, vascular endothelial growth factor, and receptor activator of NF-κB ligand (RANKL).

Conclusion: Our findings indicate that BATF crucially mediates CIA by regulating Th cell differentiation without directly affecting the functions of FLS.
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http://dx.doi.org/10.1186/s13075-018-1658-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6090970PMC
August 2018

Immunomodulatory Function of Myeloid-Derived Suppressor Cells during B Cell-Mediated Immune Responses.

Int J Mol Sci 2018 May 15;19(5). Epub 2018 May 15.

School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 61005, Korea.

Myeloid-derived suppressor cells (MDSCs) play roles in immune regulation during neoplastic and non-neoplastic inflammatory responses. This immune regulatory function is directed mainly toward T cells. However, MDSCs also regulate other cell populations, including B cells, during inflammatory responses. Indeed, B cells are essential for antibody-mediated immune responses. MDSCs regulate B cell immune responses directly via expression of effector molecules and indirectly by controlling other immune regulatory cells. B cell-mediated immune responses are a major component of the overall immune response; thus, MDSCs play a prominent role in their regulation. Here, we review the current knowledge about MDSC-mediated regulation of B cell responses.
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http://dx.doi.org/10.3390/ijms19051468DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5983618PMC
May 2018

Oxidatively Modified Protein-Disulfide Isomerase-Associated 3 Promotes Dyskerin Pseudouridine Synthase 1-Mediated Malignancy and Survival of Hepatocellular Carcinoma Cells.

Hepatology 2018 11 23;68(5):1851-1864. Epub 2018 Jul 23.

Department of Biological Sciences, College of Natural Sciences, Seoul National University, Gwanak-gu, Republic of Korea.

Dyskerin pseudouridine synthase 1 (DKC1) is a conserved gene encoding the RNA-binding protein dyskerin, which is an essential component of the telomerase holoenzyme. DKC1 up-regulation is frequently observed in many different human cancers including hepatocellular carcinoma (HCC); however, its regulatory mechanisms remain unclear. Thus, we investigated the regulatory mechanism of DKC1 in HCC progression. We found that protein-disulfide isomerase-associated 3 (PDIA3) interacted with the DKC1 regulatory DNA in HCC cells but not in HCC cells with elevated reactive oxygen species (ROS) levels, using liquid chromatographic-tandem mass spectrometric analysis after isolating the DKC1 regulatory region binding proteins. PDIA3 repressed DKC1 expression in HCC cells by recognizing the G-quadruplex DNA at the DKC1 location. However, oxidative modification of PDIA3 induced by ROS redistributed this protein into the cytosolic regions, which stimulated DKC1 expression. We also identified Met338 in PDIA3 as the oxidatively modified residue and validated the effect of oxidative modification using an ectopic expression system, a clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated 9 knock-in system, and a xenograft mouse model. We observed that oxidatively modified PDIA3 promoted DKC1-mediated malignancy and survival of HCC cells in vitro and in vivo. HCC tissues showed a positive association with ROS, cytoplasmic PDIA3, and nuclear DKC1 levels. HCC patients with high PDIA3 protein and DKC1 mRNA levels also displayed reduced recurrence-free survival rates. Cumulatively, the results showed that cytoplasmic PDIA3 activity could be essential in raising DKC1 expression in HCC progression and predicting poor prognoses in HCC patients. Conclusion: Our study indicates that the elevated ROS levels in HCC modulate cytoplasmic PDIA3 levels, resulting in HCC cell survival through DKC1 up-regulation.
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http://dx.doi.org/10.1002/hep.30039DOI Listing
November 2018

Characterization of Multiple Cytokine Combinations and TGF-β on Differentiation and Functions of Myeloid-Derived Suppressor Cells.

Int J Mol Sci 2018 Mar 15;19(3). Epub 2018 Mar 15.

School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Korea.

Myeloid-derived suppressor cells (MDSCs) regulate T cell immunity, and this population is a new therapeutic target for immune regulation. A previous study showed that transforming growth factor-β (TGF-β) is involved in controlling MDSC differentiation and immunoregulatory function in vivo. However, the direct effect of TGF-β on MDSCs with various cytokines has not previously been tested. Thus, we examined the effect of various cytokine combinations with TGF-β on MDSCs derived from bone marrow cells. The data show that different cytokine combinations affect the differentiation and immunosuppressive functions of MDSCs in different ways. In the presence of TGF-β, interleukin-6 (IL-6) was the most potent enhancer of MDSC function, whereas granulocyte colony-stimulating factors (G-CSF) was the most potent in the absence of TGF-β. In addition, IL-4 maintained MDSCs in an immature state with an increased expression of arginase 1 (Arg1). However, regardless of the cytokine combinations, TGF-β increased expansion of the monocytic MDSC (Mo-MDSC) population, expression of immunosuppressive molecules by MDSCs, and the ability of MDSCs to suppress CD4⁺ T cell proliferation. Thus, although different cytokine combinations affected the MDSCs in different ways, TGF-β directly affects monocytic-MDSCs (Mo-MDSCs) expansion and MDSCs functions.
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http://dx.doi.org/10.3390/ijms19030869DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5877730PMC
March 2018

PKCθ-Mediated PDK1 Phosphorylation Enhances T Cell Activation by Increasing PDK1 Stability.

Mol Cells 2017 Jan 26;40(1):37-44. Epub 2017 Jan 26.

School of Life Sciences and Cell Logistics Research Center, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Korea.

PDK1 is essential for T cell receptor (TCR)-mediated activation of NF-κB, and PDK1-induced phosphorylation of PKCθ is important for TCR-induced NF-κB activation. However, inverse regulation of PDK1 by PKCθ during T cell activation has not been investigated. In this study, we found that PKCθ is involved in human PDK1 phosphorylation and that its kinase activity is crucial for human PDK1 phosphorylation. Mass spectrometry analysis of wild-type PKCθ or of kinase-inactive form of PKCθ revealed that PKCθ induced phosphorylation of human PDK1 at Ser-64. This PKCθ-induced PDK1 phosphorylation positively regulated T cell activation and TCR-induced NF-κB activation. Moreover, phosphorylation of human PDK1 at Ser-64 increased the stability of human PDK1 protein. These results suggest that Ser-64 is an important phosphorylation site that is part of a positive feedback loop for human PDK1-PKCθ-mediated T cell activation.
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http://dx.doi.org/10.14348/molcells.2017.2236DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5303887PMC
January 2017

Myeloid-Derived Suppressor Cells Are Controlled by Regulatory T Cells via TGF-β during Murine Colitis.

Cell Rep 2016 12;17(12):3219-3232

School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 61005, Republic of Korea; Department of Biomedical Science and Engineering, Gwangju Institute of Science and Technology, Gwangju 61005, Republic of Korea. Electronic address:

Myeloid-derived suppressor cells (MDSCs) are well known regulators of regulatory T cells (Treg cells); however, the direct regulation of MDSCs by Treg cells has not been well characterized. We find that colitis caused by functional deficiency of Treg cells leads to altered expansion and reduced function of MDSCs. During differentiation of MDSCs in vitro from bone marrow cells, Treg cells enhanced MDSC function and controlled their differentiation through a mechanism involving transforming growth factor-β (TGF-β). TGF-β-deficient Treg cells were not able to regulate MDSC function in an experimentally induced model of colitis. Finally, we evaluated the therapeutic effect of TGF-β-mediated in-vitro-differentiated MDSCs on colitis. Adoptive transfer of MDSCs that differentiated with TGF-β led to better colitis prevention than the transfer of MDSCs that differentiated without TGF-β. Our results demonstrate an interaction between Treg cells and MDSCs that contributes to the regulation of MDSC proliferation and the acquisition of immunosuppressive functions.
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http://dx.doi.org/10.1016/j.celrep.2016.11.062DOI Listing
December 2016

Discovery and structure-activity relationship studies of quinolinone derivatives as potent IL-2 suppressive agents.

Bioorg Med Chem 2016 11 29;24(21):5357-5367. Epub 2016 Aug 29.

School of Life Sciences, Gwangju Institute of Science and Technology (GIST), Gwangju 500-712, Republic of Korea; Department of BioMedical Science and Engineering (BMSE), Gwangju Institute of Science and Technology, Gwangju 500-712, Republic of Korea. Electronic address:

The quinolinone skeleton has been utilized to develop various mechanism-based immune modulators. However, the effects of quinolinone derivatives on the release of T cell-associated interleukin-2 (IL-2) have not been established. In this study, a series of novel quinolinone derivatives was synthesized, and their immunosuppressive activity was evaluated by measuring suppression of IL-2 release from activated Jurkat T cells. Optimizing the three side chains around the quinolinone skeleton revealed the most active compound: 11l. This compound exhibits potent inhibitory activity toward IL-2 release in both 12-o-tetradecanoylphorbol-13-acetate (PMA)/A23187 (ionomycin) (IC=80±10nM) and anti-CD3/CD28-stimulated Jurkat T cells (83% inhibition at 10μM) without cytotoxic effects. Further investigation into the underlying mechanism of 11l indicated the suppression of NF-κB and nuclear factor of activated T cells (NFAT) promoter activities in Jurkat T cells.
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http://dx.doi.org/10.1016/j.bmc.2016.08.051DOI Listing
November 2016

Cereblon negatively regulates TLR4 signaling through the attenuation of ubiquitination of TRAF6.

Cell Death Dis 2016 07 28;7(7):e2313. Epub 2016 Jul 28.

Department of Molecular Cell Biology, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, 300, Cheoncheon-dong, Jangan-Gu, Suwon 440-746, Gyeonggi-Do, Republic of Korea.

Cereblon (CRBN) is a substrate receptor protein for the CRL4A E3 ubiquitin ligase complex. In this study, we report on a new regulatory role of CRBN in TLR4 signaling. CRBN overexpression leads to suppression of NF-κB activation and production of pro-inflammatory cytokines including IL-6 and IL-1β in response to TLR4 stimulation. Biochemical studies revealed interactions between CRBN and TAK1, and TRAF6 proteins. The interaction between CRBN and TAK1 did not affect the association of the TAB1 and TAB2 proteins, which have pivotal roles in the activation of TAK1, whereas the CRBN-TRAF6 interaction critically affected ubiquitination of TRAF6 and TAB2. Binding mapping results revealed that CRBN interacts with the Zinc finger domain of TRAF6, which contains the ubiquitination site of TRAF6, leading to attenuation of ubiquitination of TRAF6 and TAB2. Functional studies revealed that CRBN-knockdown THP-1 cells show enhanced NF-κB activation and p65- or p50-DNA binding activities, leading to up-regulation of NF-κB-dependent gene expression and increased pro-inflammatory cytokine levels in response to TLR4 stimulation. Furthermore, Crbn(-/-) mice exhibit decreased survival in response to LPS challenge, accompanied with marked enhancement of pro-inflammatory cytokines, such as TNF-α and IL-6. Taken together, our data demonstrate that CRBN negatively regulates TLR4 signaling via attenuation of TRAF6 and TAB2 ubiquitination.
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http://dx.doi.org/10.1038/cddis.2016.226DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4973362PMC
July 2016

Epigenetic regulation of Kcna3-encoding Kv1.3 potassium channel by cereblon contributes to regulation of CD4+ T-cell activation.

Proc Natl Acad Sci U S A 2016 08 20;113(31):8771-6. Epub 2016 Jul 20.

School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 61005, Republic of Korea; Cell Logistics Research Center, Gwangju Institute of Science and Technology, Gwangju 61005, Republic of Korea

The role of cereblon (CRBN) in T cells is not well understood. We generated mice with a deletion in Crbn and found cereblon to be an important antagonist of T-cell activation. In mice lacking CRBN, CD4(+) T cells show increased activation and IL-2 production on T-cell receptor stimulation, ultimately resulting in increased potassium flux and calcium-mediated signaling. CRBN restricts T-cell activation via epigenetic modification of Kcna3, which encodes the Kv1.3 potassium channel required for robust calcium influx in T cells. CRBN binds directly to conserved DNA elements adjacent to Kcna3 via a previously uncharacterized DNA-binding motif. Consequently, in the absence of CRBN, the expression of Kv1.3 is derepressed, resulting in increased Kv1.3 expression, potassium flux, and CD4(+) T-cell hyperactivation. In addition, experimental autoimmune encephalomyelitis in T-cell-specific Crbn-deficient mice was exacerbated by increased T-cell activation via Kv1.3. Thus, CRBN limits CD4(+) T-cell activation via epigenetic regulation of Kv1.3 expression.
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http://dx.doi.org/10.1073/pnas.1502166113DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4978309PMC
August 2016

PDK1 Is a Regulator of Epidermal Differentiation that Activates and Organizes Asymmetric Cell Division.

Cell Rep 2016 05 12;15(8):1615-23. Epub 2016 May 12.

Department of Microbiology & Immunology, Columbia University, College of Physicians & Surgeons, New York, NY 10032, USA. Electronic address:

Asymmetric cell division (ACD) in a perpendicular orientation promotes cell differentiation and organizes the stratified epithelium. However, the upstream cues regulating ACD have not been identified. Here, we report that phosphoinositide-dependent kinase 1 (PDK1) plays a critical role in establishing ACD in the epithelium. Production of phosphatidyl inositol triphosphate (PIP3) is localized to the apical side of basal cells. Asymmetric recruitment of atypical protein kinase C (aPKC) and partitioning defective (PAR) 3 is impaired in PDK1 conditional knockout (CKO) epidermis. PDK1(CKO) keratinocytes do not undergo calcium-induced activation of aPKC or IGF1-induced activation of AKT and fail to differentiate. PDK1(CKO) epidermis shows decreased expression of Notch, a downstream effector of ACD, and restoration of Notch rescues defective expression of differentiation-induced Notch targets in vitro. We therefore propose that PDK1 signaling regulates the basal-to-suprabasal switch in developing epidermis by acting as both an activator and organizer of ACD and the Notch-dependent differentiation program.
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http://dx.doi.org/10.1016/j.celrep.2016.04.051DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4909264PMC
May 2016

Secretion of IL-1β from imatinib-resistant chronic myeloid leukemia cells contributes to BCR-ABL mutation-independent imatinib resistance.

FEBS Lett 2016 Feb 25;590(3):358-68. Epub 2016 Jan 25.

School of Life Sciences, Gwangju Institute of Science and Technology, Korea.

Some cases of chronic myelogenous leukemia are resistant to tyrosine kinase inhibitors (TKIs) independently of mutation in BCR-ABL, but the detailed mechanism underlying this resistance has not yet been elucidated. In this study, we generated a TKI-resistant CML cell line, K562R, that lacks a mutation in BCR-ABL. Interleukin-1β (IL-1β) was more highly expressed in K562R than in the parental cell line K562S, and higher levels of IL-1β contributed to the imatinib resistance of K562R. In addition, IL-1β secreted from K562R cells affected stromal cell production of CXCL11, which in turn promoted migration of K562R cells into the stroma. Thus, elevated IL-1β production from TKI-resistant K562R cells may contribute to TKI resistance by increasing cell viability and promoting cell migration.
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http://dx.doi.org/10.1002/1873-3468.12057DOI Listing
February 2016

Salmonella typhimurium Suppresses Tumor Growth via the Pro-Inflammatory Cytokine Interleukin-1β.

Theranostics 2015 6;5(12):1328-42. Epub 2015 Oct 6.

1. Laboratory of In Vivo Molecular Imaging, Department of Nuclear Medicine, Chonnam National University Medical School and Hwasun Hospital, Gwangju, Republic of Korea ; 2. Department of Microbiology, Chonnam National University Medical School, Gwangju, Republic of Korea.

Although strains of attenuated Salmonella typhimurium and wild-type Escherichia coli show similar tumor-targeting capacities, only S. typhimurium significantly suppresses tumor growth in mice. The aim of the present study was to examine bacteria-mediated immune responses by conducting comparative analyses of the cytokine profiles and immune cell populations within tumor tissues colonized by E. coli or attenuated Salmonellae. CT26 tumor-bearing mice were treated with two different bacterial strains: S. typhimurium defective in ppGpp synthesis (ΔppGpp Salmonellae) or wild-type E. coli MG1655. Cytokine profiles and immune cell populations in tumor tissue colonized by these two bacterial strains were examined at two time points based on the pattern of tumor growth after ΔppGpp Salmonellae treatment: 1) when tumor growth was suppressed ('suppression stage') and 2) when they began to re-grow ('re-growing stage'). The levels of IL-1β and TNF-α were markedly increased in tumors colonized by ΔppGpp Salmonellae. This increase was associated with tumor regression; the levels of both IL-1β and TNF-α returned to normal level when the tumors started to re-grow. To identify the immune cells primarily responsible for Salmonellae-mediated tumor suppression, we examined the major cell types that produce IL-1β and TNF-α. We found that macrophages and dendritic cells were the main producers of TNF-α and IL-1β. Inhibiting IL-1β production in Salmonellae-treated mice restored tumor growth, whereas tumor growth was suppressed for longer by local administration of recombinant IL-1β or TNF-α in conjunction with Salmonella therapy. These findings suggested that IL-1β and TNF-α play important roles in Salmonella-mediated cancer therapy. A better understanding of host immune responses in Salmonella therapy may increase the success of a given drug, particularly when various strategies are combined with bacteriotherapy.
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http://dx.doi.org/10.7150/thno.11432DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4615736PMC
August 2016

Abatacept alleviates severe autoimmune symptoms in a patient carrying a de novo variant in CTLA-4.

J Allergy Clin Immunol 2016 Jan 21;137(1):327-330. Epub 2015 Oct 21.

Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, Korea; Department of Pediatrics, Seoul National University Hospital, Seoul, Korea. Electronic address:

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http://dx.doi.org/10.1016/j.jaci.2015.08.036DOI Listing
January 2016
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