Byung Cheol Lee
Korea University
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Featured researches published by Byung Cheol Lee.
Microbes and Infection | 2008
Byung Cheol Lee; Sang-Ho Choi; Tae Sung Kim
During Vibrio vulnificus infection, V. vulnificus reaches the intestine and then invades the bloodstream by crossing the intestinal mucosal barrier of the host, which results in systemic septicemia. Previously, we reported that the RtxA toxin secreted through the RtxE transporter contributes to the cytotoxicity of V. vulnificus against intestinal epithelial cells. Here, we used gene mutants of rtxE and rtxA to determine the role that V. vulnificus RtxA toxin plays in the apoptotic death of human intestinal epithelial cells. The levels of DNA fragmentation were lower in human epithelial cells infected with an rtxE mutant of V. vulnificus than in those that were infected with the wild type. In addition, the rtxE mutant was found to induce lower levels of TUNEL positive cells and cell cycle arrest at the subG(1) than the wild type V. vulnificus. Furthermore, the decreased levels of DNA fragmentation, TUNEL positive cells and subG(1) arrest by the rtxE gene mutation were restored by the complementation of an rtxE gene into the rtxE mutant V. vulnificus. Finally, the rtxA mutant induced significantly lower levels of apoptotic cell death than the wild type. The levels of the PARP, cytochrome c, caspase-3, and mitochondrial membrane depolarization were lower in human epithelial cells infected with the rtxE and rtxA mutants, compared with the wild type and rtxE gene-complemented strains of V. vulnificus. Taken together, these results indicate that V. vulnificus RtxA toxin induces the apoptotic death through a mitochondria-dependent pathway in human intestinal epithelial cells exposed to V. vulnificus.
Infection and Immunity | 2008
Byung Cheol Lee; Jeong Hyun Lee; Myung Won Kim; Byoung Sik Kim; Man Hwan Oh; Kun-Soo Kim; Tae Sung Kim; Sang-Ho Choi
ABSTRACT Numerous secreted virulence factors have been proposed to account for the fulminating and destructive nature of Vibrio vulnificus infections. A mutant of V. vulnificus that exhibited less cytotoxicity to INT-407 human intestinal epithelial cells was screened from a library of mutants constructed by random transposon mutagenesis. A transposon-tagging method was used to identify and clone an open reading frame encoding an RTX toxin secretion ATP binding protein, RtxE, from V. vulnificus. The deduced amino acid sequence of RtxE from V. vulnificus was 91% identical to that reported from Vibrio cholerae. Functions of the rtxE gene in virulence were assessed by constructing an isogenic mutant whose rtxE gene was inactivated by allelic exchanges and by evaluating the differences between its virulence phenotype and that of the wild type in vitro and in mice. The disruption of rtxE blocked secretion of RtxA to the cell exterior and resulted in a significant reduction in cytotoxic activity against epithelial cells in vitro. Also, the intraperitoneal 50% lethal dose of the rtxE mutant was 104 to 105 times higher than that of the parental wild type, indicating that RtxE is essential for the virulence of V. vulnificus. Furthermore, the present study demonstrated that the rtxBDE genes are transcribed as one transcriptional unit under the control of a single promoter, PrtxBDE. The activity of V. vulnificus PrtxBDE is induced by exposure to INT-407 cells, and the induction requires direct contact of the bacteria with the host cells.
Infection and Immunity | 2006
Na Young Park; Jeong Hyun Lee; Myung Won Kim; Hee Gon Jeong; Byung Cheol Lee; Tae Sung Kim; Sang-Ho Choi
ABSTRACT A wbpP gene encoding a putative UDP-N-acetyl-d-glucosamine C4 epimerase was identified and cloned from Vibrio vulnificus. The functions of the wbpP gene, assessed by the construction of an isogenic mutant and by evaluating its phenotype changes, demonstrated that WbpP is essential in both the pathogenesis and the capsular polysaccharide biosynthesis of V. vulnificus.
International Journal of Molecular Medicine | 2011
Byung Cheol Lee; Myun Soo Kim; Sang-Ho Choi; Tae Sung Kim
Bacterial virulence factors and secreted extracellular proteins from damaged host cells following infection have been recognized as key mediators in the pathophysiological alterations observed in septic shock, and have also been shown to have a synergistic influence on bacterial pathogenicity. We hypothesized that during infections, virulence factors as well as host-shed proteins may synergistically influence aspects of the pathogenicity of V. vulnificus, such as primary septic shock and overproduction of proinflammatory cytokines. However, virulence factors and host-derived proteins have yet to be clearly evaluated during V. vulnificus infection. In this study, we analyzed and compared the proteins in conditioned supernatants generated from co-cultures of host cells and either wild-type or rtxE mutant V. vulnificus using LC-QTOF-MS/MS analysis. In a previous study, we determined that the culture supernatants of the rtxE mutant V. vulnificus-infected INT-407 cells induced significantly lower levels of IL-8 production from human intestinal epithelial cells than did the culture supernatants of wild-type V. vulnificus-infected INT-407 cells. LC-QTOF-MS/MS analysis results demonstrated that levels of proteins such as HSP90 α/β, 14-3-3 γ, PRX II, hnRNP K, β-actin, α-tubulin and V. vulnificus flagellin were significantly lower in the culture supernatants of rtxE mutant V. vulnificus-infected INT-407 cells than in the culture supernatants of wild-type V. vulnificus-infected INT-407 cells. These results demonstrate that V. vulnificus RTX toxins acting via rtxE, a transporter of virulence factors, play a very important role in the pathogenesis of V. vulnificus, as well as in its initial role in inducing pathogenic mediators from host cells.
Journal of Microbiology | 2007
Jeong Hyun Lee; Myung Won Kim; Byoung Sik Kim; Seung Min Kim; Byung Cheol Lee; Tae Sung Kim; Sang-Ho Choi
Journal of Microbiology and Biotechnology | 2007
Jeong Hyun Lee; Jee Eun Rhee; Uryung Park; Hyun Mok Ju; Byung Cheol Lee; Tae Sung Kim; Hye Sook Jeong; Sang-Ho Choi
International Journal of Molecular Medicine | 2009
Byung Cheol Lee; Myun Soo Kim; Sang-Ho Choi; Kwang Yoon Kim; Tae Sung Kim
Biomolecules & Therapeutics | 2008
Huayue Li; Byung Cheol Lee; Tae Sung Kim; Kyung Sook Bae; Jongki Hong; Sang-Ho Choi; Baoquan Bao; Jee Hyung Jung
International Journal of Molecular Medicine | 2010
Byung Cheol Lee; Myun Soo Kim; Sang-Ho Choi; Tae Sung Kim
International Journal of Molecular Medicine | 2010
Byung Cheol Lee; Myun Soo Kim; Daeho Cho; Sang-Ho Choi; Tae Sung Kim
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Korea Research Institute of Bioscience and Biotechnology
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