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Functional Characteristics of C-terminal Lysine to Cysteine Mutant Form of CTLA-4Ig
Kim, Bongi,Shin, Jun-Seop,Park, Chung-Gyu The Korean Association of Immunobiologists 2013 Immune Network Vol.13 No.1
CTLA-4Ig is regarded as an inhibitory agent of the T cell proliferation via blocking the costimulatory signal which is essential for full T cell activation. To improve applicability, we developed the CTLA-4Ig-CTKC in which the c-terminal lysine had been replaced by cysteine through single amino acid change. The single amino acid mutation of c-terminus of CTLA-4Ig was performed by PCR and was checked by in vitro transcription and translation. DNA construct of mutant form was transfected to Chinese hamster ovary (CHO) cells by electroporation. The purified proteins were confirmed by Western blot and B7-1 binding assay for their binding ability. The suppressive capacity of CTLA-4Ig-CTKC was evaluated by the mixed lymphocyte reaction (MLR) and in the allogeneic pancreatic islet transplantation model. CTLA-4Ig-CTKC maintained binding ability to B7-1 molecule and effectively inhibits T cell proliferation in MLR. In the murine allogeneic pancreatic islet transplantation, short-term treatment of CTLA-4Ig-CTKC prolonged the graft survival over 100 days. CTLA-4Ig-CTKC effectively inhibits immune response both in MLR and in allogeneic islet transplantation model, indicating that single amino acid mutation does not affect the inhibitory function of CTLA-4Ig. CTLA-4Ig-CTKC can be used in vehicle-mediated drug delivery system such as liposome conjugation.
Park, Min-Jung,Shin, Jun-Seop,Kim, Yong-Hee,Hong, So-Hee,Yang, Seung-Ha,Shin, Jin-Young,Kim, Su-Young,Kim, Bongi,Kim, Jung-Sik,Park, Chung-Gyu Humana Press 2011 Stem cell reviews and reports Vol.7 No.2
<P>Mesenchymal stem cells (MSCs) are multipotent, non-hematopoietic stem cells that exhibit the capacity to inhibit the proliferation of a variety of immune cells. However, the underlying mechanisms of the immunosuppressive effects of MSCs are still obscure. Therefore, we attempted to identify the mechanisms underlying immunosuppression toward the activated T lymphocytes by MSCs in a murine model. In particular, we aimed to find possible factors derived from MSCs that drive this phenomenon. We found that T lymphocytes incubated with conditioned media of MSCs (MSC CM) entered into apoptosis and were subjected to cell cycle arrest during the course of activation, and these phenomena were accompanied by the reduction of IL-2 production. Specifically, matrix metalloproteinases (MMPs) derived from MSCs caused cleavage of IL-2 receptor α (CD25) from the surface of activated T cells, and as a consequence, IL-2 signaling in response to engagement of the IL-2 receptor (IL-2R) was downregulated. The inhibition of MMP activity in the MSC CM by GM6001 abrogated CD25 cleavage and restored IL-2 production from the activated splenocytes. However, the blockade of MMP activity could not fully restore the proliferative response and apoptosis of T cells altered by MSC CM. In conclusion, MSC-derived MMPs have a significant role in the suppression of IL-2 production through induction of CD25 cleavage and have a partial role in the suppression of T cell proliferation.</P>
Structure of the Human Gene Encoding the MAp19 and MASP-2 Proteins
Park, Dongkyu,Kim, Bongy,Baek, Kwanghee,Yoon, Jaeseung 한국유전학회 2002 Genes & Genomics Vol.24 No.3
We have characterized the complete structure of the human gene encoding the MAp19 and MASP-2 proteins which are involved in one of the important innate immune defense mechanisms of the hosts. The mRNA species encoding MASP-2 and MAp19 are encoded by the alternative splicing and polyadenylation from a single structural gene. The gene consists of 12 exons. The four exons are common to both MAp19 and MASP-2 transcripts, one exon is specific for MAp19 transcript, and seven exons are specific for MASP-2 transcript. The transcription start point was determined by 5'-RACE analysis.
Soluble mediators from mesenchymal stem cells suppress T cell proliferation by inducing IL-10
Seung-Ha Yang,Min-Jung Park,Il-Hee Yoon,Su-Young Kim,So-Hee Hong,Jin-Young Shin,Hye-Young Nam,김용희,Bongi Kim,박정규 생화학분자생물학회 2009 Experimental and molecular medicine Vol.41 No.5
Mesenchymal stem cells (MSCs) can inhibit T cell proliferation; however, the underlying mechanisms are not clear. In this study, we investigated the mechanisms of the immunoregulatory activity of MSCs on T cells. Irradiated MSCs co-cultured with either naïve or pre-activated T cells in a mixed lymphocyte reaction (MLR) significantly suppressed T cell proliferation in a dose-dependent manner, irrespective of allogeneic disparity between responders and MSCs. Transwell assays revealed that the suppressive effect was primarily mediated by soluble factors that induced apoptosis. Splenocytes stimulated with alloantigen in the presence of the MSC culture supernatant (CS) produced a significant amount of IL-10, which was attributed to an increase in the number of IL-10 secreting cells, confirmed by an ELISPOT assay. The blockade of IL-10 and IL-10 receptor interaction by anti-IL-10 or anti-IL-10-receptor antibodies abrogated the suppressive capacity of MSC CS, indicating that IL-10 plays a major role in the suppression of T cell proliferation. The addition of 1-methyl-DL-tryptophan (1-MT), an indoleamine 2,3-dioxygenase (IDO) inhibitor, also restored the proliferative capacity of T cells. In conclusion, we demonstrated that soluble mediators from culture supernatant of MSCs could suppress the proliferation of both naïve and pre-activated T cells in which IL-10 and IDO play important roles.