Publications (150) View all
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Article: Toll-like receptor 4 signalling attenuates experimental allergic conjunctivitis.
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ABSTRACT: Allergic conjunctivitis from an allergen-driven T helper type 2 (Th2) response is characterized by conjunctival eosinophilic infiltration. Association between signalling through Toll-like receptor 4 (TLR-4) and adaptive immune responses has been observed in allergic airway disease. We examined whether administration of bacterial lipopolysaccharide (LPS), a prototypic bacterial product that activates immune cells via TLR-4, could affect the development of allergic conjunctivitis and modify the immune response to ovalbumin (OVA) allergen in an experimental allergic conjunctivitis (EAC) model. Mice were challenged with two doses of OVA via conjunctival sac after systemic challenge with OVA in alum. Several indicators for allergy were evaluated in wild-type and TLR-4(-/-) mice with or without adding of different doses of LPS into OVA in alum. Mice challenged with OVA via conjunctival sac following systemic challenge with OVA in alum had severe allergic conjunctivitis. Of interest, LPS administration markedly suppressed immunoglobulin (Ig)E-mediated and eosinophil-dependent conjunctival inflammation. In addition, mice sensitized with OVA plus LPS had less interleukin (IL)-4, IL-5 and eotaxin secretion than mice sensitized with OVA only. The suppression of allergic response by LPS administration was due to Th1 shift. In contrast, the presence of LPS during sensitization with OVA had no effect on severity of allergic conjunctivitis and Th2 responses in TLR4-4(-/-) mice. Our findings demonstrate, for the first time, that LPS suppresses Th2 responses via the TLR-4-dependent pathway in the EAC model.Clinical & Experimental Immunology 03/2011; 164(2):275-81. · 3.36 Impact Factor -
Article: Q455V mutation in COL8A2 is associated with Fuchs' corneal dystrophy in Korean patients.
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ABSTRACT: To investigate the possibility of collagen type VIII alpha2 (COL8A2) as a potential susceptibility gene for Korean patients with Fuchs' corneal dystrophy (FECD), we performed mutation screening of the COL8A2 gene. A total of 25 FECD patients were screened, including 15 patients from six pedigrees with early onset FECD and an additional 10 unrelated patients, all of Korean ancestry. Seventy-three control individuals without corneal disease were selected from the general population. PCR-SSCP and direct sequencing were used to screen genetic variations in COL8A2. The pathogenic impact of these sequence variants was evaluated through the SIFT and PolyPhen algorithms. We have identified a novel heterozygous mutation, Q455V, in exon 2 of COL8A2. All patients of Korean pedigrees with FECD had the Q455V mutation, and two out of nine unrelated cases also had this mutation. But it was not present in unaffected individuals from these pedigrees or from control groups. Two heterozygous missense mutations, R155Q and T502M, were also observed, but, they showed no significant difference between FECD patients and controls. The allele frequencies of A35A and G495G, which were synonymous substitutions, were significantly associated with FECD. Both Q455V and T502M were predicted as deleterious mutations by computational methods using PolyPhen and SIFT. Our data constitute the first report of a heterozygous Q455V mutation of the COL8A2 gene in Korean patients with FECD. Q455V may be the causative defect in the development and progression of Korean FECD patients.Eye (London, England) 06/2008; 23(4):895-903. · 1.97 Impact Factor -
Article: Ligand release-independent transactivation of epidermal growth factor receptor by transforming growth factor-beta involves multiple signaling pathways.
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ABSTRACT: Many of the signaling responses induced by transforming growth factor-beta (TGF-beta) are mediated by Smad proteins, but there is evidence that it can also signal independently of Smads. Here, we provide evidence that multiple signal pathways induced by TGF-beta1-including Src family tyrosine kinases (SFKs), generation of reactive oxygen species (ROS), de novo protein synthesis and E-cadherin-dependent cell-cell interactions-transactivate the epidermal growth factor receptor (EGFR), which in turn regulates expression of c-Fos and c-Jun. Immunoprecipitation and immunofluorescence staining showed that EGFR was phosphorylated on tyrosine in response to TGF-beta1. EGFR transactivation required the activation of SFKs and the production of ROS via NADPH oxidase, but was not dependent on metalloproteases or the release of EGF-like ligands. In addition, the production of ROS was dependent on signaling by specific SFKs as well as de novo protein synthesis. Stable transfection of E-cadherin into MDA-MB-231 cells as well as E-cadherin-blocking assays revealed that E-cadherin-mediated cell-cell interactions were also essential for EGFR transactivation. Finally, EGFR transactivation was involved in the expression of c-Fos and c-Jun via the extracellular signal-regulated kinase signaling cascade. Taken together our data suggest that ligand release-independent transactivation of EGFR may diversify early TGF-beta signaling and represent a novel pathway leading to TGF-beta-mediated gene expression.Oncogene 02/2008; 27(5):614-28. · 6.37 Impact Factor -
Article: BIGH3 gene mutations and rapid detection in Korean patients with corneal dystrophy.
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ABSTRACT: Mutations in the BIGH3 gene on chromosome 5q31 cause four distinct autosomal dominant corneal dystrophies. We sought to determine whether the BIGH3 gene mutation was responsible for corneal dystrophy in Korean patients. Polymerase chain reaction single strand conformational polymorphism (PCR-SSCP) analysis was performed with the DNA from patients and healthy individuals. We sequenced the PCR products with the aberrant SSCP pattern to identify the mutation. Mutant-specific reverse primers were used to screen genomic DNA for the identified mutations. We identified mutations R124C in the CDL1 family and R124H in four families with a granular dystrophy. We identified our granular dystrophy to be Avellino corneal dystrophy (ACD). Eighteen of 20 patients with a granular dystrophy contained the same R124H mutation, indicating that mutation R124H was very common in Korean patients with ACD. During this study, we identified a new polymorphism (T1667C, F540F). This is the first report of mutations found in the BIGH3 gene in Korean families with corneal dystrophy. We report that the majority (90%) of ACD patients in Korea carry the R124H mutation. Mutant-specific reverse primers can be used to screen efficiently for CDL1 and ACD.Cornea 12/2001; 20(8):844-9. · 1.73 Impact Factor -
Article: Attenuation of Zn2+ neurotoxicity by aspirin: role of N-type Ca2+ channel and the carboxyl acid group.
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ABSTRACT: Synaptically released Zn2+ ions enter into neurons primarily through voltage-gated Ca2+ channels (VGCC) or N-methyl-d-aspartate (NMDA) receptors, which can mediate pathological neuronal death. We studied the possibility (and underlying mechanisms) that aspirin, known to prevent NMDA neurotoxicity, would also attenuate Zn2+ neurotoxicity. Administration of 3 to 10 mM aspirin, in cortical cell cultures, attenuated the evolution of neuronal death following exposure to 300 microM Zn2+ for 30 min. This neuroprotective effect of aspirin was attributable to the prevention of Zn2+ ion entry. Aspirin interfered with inward currents and an increase in [Ca2+]i through VGCC and selective binding of omega-conotoxin, sensitive to N-type Ca2+ channel. The omega-conotoxins GVIA or MVIIC, the selective inhibitors of N-type Ca2+ channels, attenuated Zn2+ neurotoxicity. Aspirin derivatives lacking the carboxyl acid group did not reduce Zn2+ neurotoxicity. The present findings suggest that aspirin prevents Zn2+-mediated neuronal death by interfering with VGCC, and its action specifically requires the carboxyl acid group.Neurobiology of Disease 11/2001; 8(5):774-83. · 5.40 Impact Factor
