Yun Hui Choi

• phD
• Yonsei University

Despite intensive clinical and scientific efforts, the mortality rate of sepsis remains high due to the lack of precise biomarkers for patient stratification and therapeutic guidance. Secreted human tryptophanyl-tRNA synthetase 1 (WARS1), an endogenous ligand for Toll-like receptor (TLR) 2 and TLR4 against infection, activates the genes that signif...

While cytoplasmic tryptophanyl-tRNA synthetase (WARS1) ligates tryptophan (Trp) to its cognate tRNAs for protein synthesis, it also plays a role as an innate immune activator in extracellular space. However, its secretion mechanism remains elusive. Here, we report that in response to stimuli, WARS1 can be secreted via two distinct pathways: via Trp...

Helicobacter pylori colonizes human gastric mucosa. Its infection is associated with gastric diseases including gastric cancer. CagA is one of the most important toxins produced by H. pylori. It is related to gastric cancer which can be injected into host cells via a type IV secretion system (T4SS). CagL is a structural component of T4SS apparatus,...

Tryptophanyl-tRNA synthetase 1 (WARS1) is an endogenous ligand of mammalian Toll-like receptors (TLR) 2 and TLR4. Microarray data, using mRNA from WARS1-treated human peripheral blood mononuclear cells (PBMCs), had indicated WARS1 to mainly activate innate inflammatory responses. However, exact molecular mechanism remains to be understood. The trig...

Backgrounds and Objective Increased neutrophil infiltration and osteoclast formation are key characteristics of periodontitis. The effect of these neutrophils on osteoclast formation in periodontitis remains unclear. Therefore, we investigated the effects of neutrophils on osteoclast formation in a neutrophil‐deficient mouse model of periodontitis....

Infection with CagA+ Helicobacter pylori strains is linked to an increased risk for gastric diseases, including gastric cancer. Recent evidence indicates that dynamic expansion and contraction of cagA copy number may serve as a novel mechanism to enhance disease development. Herein, comparative genomic analysis divided hpEurope into two groups: hpE...

Background: Periodontitis is an infectious disease that manifests as alveolar bone loss surrounding the roots of teeth. Diabetes aggravates periodontitis-induced alveolar bone loss via suppression of bone formation. Intermittent parathyroid hormone (PTH) administration displays an anabolic effect on bone. In this study, we investigated the effect...

Helicobacter pylori is associated with hypergastrinemia, which has been linked to the development of gastric diseases. Although the molecular mechanism is not fully understood, H. pylori is known to modulate the Erk pathway for induction of gastrin expression. Herein we found that an epidermal growth factor (EGF) receptor kinase inhibitor significa...

Specific primers utilized for qRT-PCR.

Field emission scanning electron microscopy analysis of the T4SS apparatus of H. pylori co-cultured with AGS cells. AGS cells were co-cultured at a MOI of 100 for 4 h with wild-type H. pylori strains G27 or K74, as well as their isogenic mutant derivatives, ΔcagA and ΔcagL, to analyze the presence of T4SS by high resolution field emission scanning...

Sequences of siRNAs used in this study.

H. pylori infection increases gastrin expression in gastric epithelial cells. Gastrin mRNA expression was measured by qRT-PCR using RNA isolated at the indicated times after AGS cells were infected with H. pylori G27 WT. *P < 0.05 compared to 0 h.

Effect of H. pylori infection on EGFR-mediated MAPK activation. (A) Erk activation was measured by Western blot at the indicated time points after AGS cells were infected with H. pylori G27 WT for the indicated durations, with or without pretreatment of AG1478 (1 μM) for 30 min. (B) AGS cells were infected with G27 WT, G27ΔcagA, and G27ΔPAI for 5 h...

siRNA Knockdown of HB-EGF does not alter induction of IL-8 secretion. AGS cells were treated with NT siRNA (100 pM), or HB-EGF siRNA (50 and 100 pM). At 48 h after siRNA treatment, cells were infected with H. pylori strain G27 at an MOI of 100 for 5 h. Bar graphs indicate mean IL-8 secretion and error bars indicate standard deviation. **P < 0.01.

siRNA Knockdown of HB-EGF does not alter cell elongation. AGS cells were treated with NT siRNA (100 pM), or HB-EGF siRNA (50 and 100 pM). At 48 h after siRNA treatment, cells were infected with H. pylori strain G27 at an MOI of 100 for 5 h. Cells were fixed with 4% paraformaldehyde and images were taken under ×200 magnification.

Type 1 diabetes with periodontitis shows elevated TNF-α expression. Tumor necrosis factor (TNF)-α stimulates the expression of receptor activator of nuclear factor-κB ligand (RANKL) and sclerostin. The objective of this study was to determine the effect of TNF-α expression of osteocytic RANKL and sclerostin in type 1 diabetes rats with periodontiti...

Experimental scheme for IFX treatment, body weight, and glucose levels during the experimental period. Experimental scheme (A). Body weight (B) and fasting glucose levels (C) for experimental groups. There are 6, 6, 8, and 8 rats in C, P, DP, and DP+IFX groups, respectively, at each time point.* P < 0.05 compared to C group. # P < 0.05. (TIF)

List of primer sequences used in this study. (DOCX)

Infection with Helicobacter pylori is a major risk factor for development of gastric disease, including gastric cancer. Patients infected with H.?pylori strains that express CagA are at even greater risk of gastric carcinoma. Given the importance of CagA, this report describes a new molecular mechanism by which the cagA copy number dynamically expa...

The array of outer membrane proteins (OMPs) found in Helicobacter pylori provides a crucial component for persistent colonization within the gastric niche. Not only does H. pylori harbor a wide number of OMPs, but these OMPs often vary across strains; this likely contributes to immune evasion, adaptation during long term colonization, and potential...

Areca nut (AN) chewing is a habit in many countries in Central, Southern, and Southeast Asia. It is strongly associated with the occurrence of oral, pharyngeal, and esophageal cancer as well as systemic inflammation. However, the association between AN intake and the development of gastric lesions has not yet been identified. The aim of this study...

Background & aims: Wogonin is a flavonoid extracted from the root of Scutellaria baicalensis Gerogi. We evaluated the therapeutic effects of wogonin using db/db mice. Methods: Mice received wogonin or vehicle by oral gavage for 2 weeks. Blood glucose, insulin, and cholesterol levels were measured, and liver morphology was observed with histopath...

Helicobacter pylori is an important factor of chronic gastritis, digestive ulcer, and stomach cancer. CagL, a virulence factor of H. pylori, is well-known as a pilus protein which acts as adhesion to host cell and a component of Type 4 secretion system. In this study, we evaluated the protective response of recombinant CagL protein (rCagL) using Mo...

Author Summary Herpesvirus persists in its host by entering a latent state, periodically reactivating to produce infectious viral particles. Some of the herpesviruses have also been known to be related to cancers. Herpesvirus saimiri (HVS), an oncogenic monkey herpesvirus, persists in the T lymphocytes of its natural host, the squirrel monkey, with...

Secondary structure prediction of the N-terminal region of Tip from Herpevirus saimiri strains and Tio from Herpesvirus ateles, performed using PSIPRED (http://bioinf.cs.ucl.ac.uk/psipred/psiform.html). The predicted amphipathic helix (red box) and the transmembrane domain (blue box) are indicated. (0.14 MB PDF)

Quantitative analysis of binding between peptides and lipids. Numerical densitometric values obtained from Figure 5B were plotted as percentages of the maximum binding of peptides to each lipids (the highest value, for peptide binding to 100 pmol of lipids, was arbitrarily assigned “100% binding”). To estimate the saturated binding, 3-parameter sig...

Quantification of colocalization of Tip wt211-256, Tip amp1211-256, and Tip CD71TM211-256 with early endosomes or late endosome/lysosomes. Jurkat T cells expressing the GFP-fusion proteins were analyzed for colocalization with EEA1 or LAMP2 as described in Fig. 4A (A). In addition, HeLa cells expressing the GFP-fusion proteins were also analyzed fo...

TM domain amino acids contributing to lipid raft association, identified by alanine scan mutagenesis. (A) Sequences of wild type Tip, and its mutants carrying alanine scan mutations in their TM domain. (B) 293T cells transiently expressing wild type Tip or its mutants were lysed and processed for lipid raft fractionation. Proteins from each fractio...

Schematic representation of GFP fusion proteins of wild type or mutant Tip. In GFP-Tip amp2, which is not shown here, the positively-charged amino acids of the amphipathic helix are point-mutated into alanine (Figure 2A). (0.05 MB PDF)

Lipid raft association of flag-tagged Tip or its deletion mutant. 293T cells were transfected with plasmids encoding Tip or its deletion mutants as flag-tagged proteins, and processed for lipid raft fractionation. Proteins from each fraction of the sucrose gradient were subjected to immunoblotting with an anti-flag antibody to detect Tip or its mut...

Quantification of colocalization of Tip wt and Tip amp1 with early endosomes, late endosome/lysosomes, or CD3ζ. Jurkat T cells electroporated with plasmids encoding Tip or Tip amp1 were analyzed for Tip, Tip amp1, EEA1, LAMP2, CD3ζ colocalization as described in Fig. 3B. Pearson coefficient (R) values were obtained from 10 to 20 cells as described...

Size changes of liposomes following addition of amphipathic peptides. For the quantitative analysis of liposome tubulation, a laser light scattering assay was used, in which the morphological changes are estimated indirectly by measuring the size changes of liposomes. The liposomal size distribution was significantly altered by the addition of the...

The effect of mutations in amphipathic helix or transmembrane domain of Tip on the membrane association. The efficiency of membrane association of Tip and its mutants were measured by comparing the ratio of the proteins in whole cell lysate (WCL) and membrane-enriched fraction (MF). GFP fusion proteins in the 2% of WCL or 10% of MF were detected by...

Serotonin receptor subtype 6 (5-HT(6)) is a neurotransmitter receptor, which is involved in various brain functions such as memory and mood. It mediates signaling via the interaction with a stimulatory G-protein. Especially, the third intracellular loop (iL3) of 5-HT(6) and the alpha subunit of stimulatory G protein (G alpha(s)) are responsible for...

Serotonin receptor subtype 6 (5-HT6) is a neurotransmitter receptor, which is involved in various brain functions such as memory and mood. It mediates signaling via the interaction with a stimulatory G-protein. Especially, the third intracellular loop (iL3) of 5-HT6 and the alpha subunit of stimulatory G protein (G alpha(s)) are responsible for the...

The serotonin type 6 (5-HT(6)) receptor is a G-protein coupled receptor (GPCR) coupled to a stimulatory G-protein (G(S)). To identify the structural basis for the interaction of the 5-HT(6) receptor with the G(S) protein, we have dissected the interaction between GST-fusion proteins containing the second intracellular loop (iL2), the third intracel...