Jin Koo Kim

Protective antitumor activity through dendritic cell immunization is mediated by NK cell as well as CTL activation

Dendritic cells (DCs) are potent professional antigen-presenting cells (APC) capable of inducing the primary T cell response to antigen. Although tumor cells express target antigens, they are incapable of stimulating a tumor-specific immune response due to a defect in the costimulatory signal that is required for optimal activation of T cells. In this work, we describe a new approach using tumor-DC coculture to improve the antigen presenting capacity of tumor cells, which does not require a source of tumor-associated antigen. Immunization of a weakly immunogenic and progressive tumor cocultured with bone marrow-derived DCs generated an effective tumor vaccine. Immunization with the cocultured DCs was able to induce complete protective immunity against tumor challenges and was effective for the induction of tumor-specific CTL (cytotoxic T lymphocyte) activity. Furthermore, high NK cell activity was observed in mice in which tumors were rejected. In addition, immunization with tumor-pulsed DCs induced delayed tumor growth, but not tumor eradication in tumor-bearing mice. Our results demonstrate that coculture of DCs with tumors generated antitumor immunity due to the NK cell activation as well as tumor-specific T cell. This approach would be useful for designing tumor vaccines using DCs when the information about tumor antigens is limited.

DIFFERENTIAL EXPRESSION OF FERRITIN HEAVY CHAIN IN THP-1 CELLS INFECTED WITH MYCOBACTERIUM BOVIS BCG

To identify the host genes induced or suppressed by infection of mycobacteria, the reverse transcriptase polymerase chain reaction (RT‐PCR) and the differential display reverse transcriptase polymerase chain reaction (DD RT‐PCR) methods were used. In this study, cDNAs complement to mRNA extracted from human peripheral monocyte derived naive THP‐1 cells, THP‐1 cells infected with live Mycobacterium bovis BCG, THP‐1 cells treated with heat‐killed BCG, and THP‐1 cells incubated with IgG‐coated glass‐beads were compared on the sequencing gel. One (TG2‐1) of the clones selected by DD RT‐PCR is 446 bp long and is identical to human ferritin heavy (H) chain gene. Northern blot analysis confirmed that ferritin H chain gene has been markedly over‐expressed in monocytic THP‐1 cells incubated with live and dead M. bovis BCG. Differential display techniques of host genes whose expression levels were varied by infection of mycobacteria could provide information about the response of macrophages to mycobacterial infection.

Korea Barcode of Life Database System (KBOL)

A major concern regarding the collection and storage of biodiversity information is the inefficiency of conventional taxonomic approaches in dealing with a large number of species. This inefficiency has increased the demand for automated, rapid, and reliable molecular identification systems and large-scale biological databases. DNA-based taxonomic approaches are now arguably a necessity in biodiversity studies. In particular, DNA barcoding using short DNA sequences provides an effective molecular tool for species identification. We constructed a large-scale database system that holds a collection of 5531 barcode sequences from 2429 Korean species. The Korea Barcode of Life database (KBOL, http://koreabarcode.org) is a web-based database system that is used for compiling a high volume of DNA barcode data and identifying unknown biological specimens. With the KBOL system, users can not only link DNA barcodes and biological information but can also undertake conservation activities, including environmental management, monitoring, and detecting significant organisms.

COMPLETE SEQUENCE OF THE UPP GENE ENCODING URACIL PHOSPHORIBOSYLTRANSFERASE FROM MYCOBACTERIUM BOVIS BCG

The nucleotide sequence of a 799 bp fragment of Mycobacterium bovis BCG containing the putative upp genc that encodes a uracil phosphoribosyltransferase (UPRTase [EC 2.4.2.9]) has been determined. The upp gene of BCG has an open reading frame (ORF) of 621 bp (207 amino acids) starting with GTG (position 112) and ending with TGA (position 733), and its molecular mass was calculated to be 21,864 Da. Comparative analyses of the deduced amino acid sequence of BCG UPRTasc with the UPRTase of six bacterial genera revealed that 24% (50/211) of the residues are perfectly conserved and 32% (67/211) of the residues arc well conserved.

CLONING AND SEQUENCING OF THE SECY GENE HOMOLOG FROM MYCOBACTERIUM BOVIS BCG

The complete nucleotide sequence of a 1,513 bp fragment of Mycobacterium bovis BCG containing the secY gene homolog and partial adk gene that encodes an adenylate kinase has been determined. The secY gene of BCG has an open reading frame of 441 amino acids with homology to the SecY protein family. Comparative analyses of the deduced amino acid sequence of additional partial ORF revealed strong similarity to the known adenylate kinases.

Molecular cloning of the leub genes from Mycobacterium bovis BCG and Mycobacterium tuberculosis

A gene responsible for the biosynthesis of leucine has been cloned by the complementation of the Escherichia coli leuB6 auxotroph mutant after transformation with the Mycobacterium bovis BCG genomic DNA library, which was constructed by ligating the partially digested BCG DNA with Sau3AI into the pUC 19 digested with BamHI. Sequencing of the leuB gene of BCG revealed an ORF (open reading frame) of 1,011 bp encoding isopropytmalate dehydrogenase with a calculated molecular weight of 42 kDa. The leuB gene of Mycobacterium tuberculosis isolated from Korean tuberculosis patient is shown to be identical to that of BCG except one bp.