Regulation of Plasmodium falciparum DNA polymerase alpha

Choi, Inpyo 한국생화학분자생물학회 1991 생화학분자생물학회 소식 Vol.11 No.3

Generating Natural Killer Cells from Hematopoietic Stem Cells for Cancer Immunotherapy

Inpyo CHOI 한국생물공학회 2017 한국생물공학회 학술대회 Vol.2017 No.4

VDUP1 signaling in immune and cancer cells

Choi, Inpyo 이화여자대학교 세포신호전달연구센터 2006 고사리 세포신호전달 심포지움 Vol. No.8

Vitamin D₃ up-regulated protein 1(VDUP1) is a stress-response gene which is up-regulated by 1,25(OH)₂D₃ in many cells. In tumor tissues, the expression of VDUP1 was reduced as compared to normal controls. Upon stimulation by growth-inhibitory signals such as TGF-β1 and 1,25(OH)₂D₃, its expression was rapidly up-regulated as the cell growth was retarded. The transfection of VDUP1 in tumor cells reduced cell growth. The VDUP1 expression was also increased when the cell-cycle progression was arrested. Transfection of VDUP1 induced cell-cycle arrest at the G0/G1 phase, indicating that VDUP1 possesses a tumor-suppressive activity. The in vivo roles of VDUP1 were investigated by producing mice lacking VDUP1(VDUP1^(-/-) mice). Here, we demonstrate that VDUP1^(-/-) mice showed severe lymphoid hyperplasia in the small intestine and increased tumor susceptibility to carcinogen. VDUP1^(-/-) mice had a profound reduction in the numbers of NK cells. In addition, these mice showed decreased NK activity and reduced CD122 expression. Meanwhile, we found that VDUP1^(-/-) fibroblast cells proliferated more compared to wild-type cells with reduced expression of p27^(kip1), a cyclin-dependent kinase inhibitor. Jab1 is known to interact with p27^(kip1) and to decrease the stability of p27^(kip1). VDUP1 interacted with jab1 and restored jab1-induced suppression of p27^(kip1) stability. In this process, VDUP1 blocked the jab1-mediated translocation of p27^(kip1) from the nucleus to the cytoplasm. In addition, VDUP1 inhibited jab1-mediated AP-1 activation and cell proliferation. Taken together, these results indicate that VDUP1 is a novel factor for the tumorigenesis and NK maturation in vivo.

Roles of ROS in TGF-β1 signaling

Choi, Inpyo 이화여자대학교 세포신호전달연구센터 2001 고사리 세포신호전달 심포지움 Vol. No.3

To investigate the possible roles of reactive oxygen species(ROS) in transforming growth factor-β1(TGF-β1) signal transduction, quiescent human lung fibroblast(HLF) cells were stimulated with TGF-β1. TGF-β1 stimulation resulted in rapid and transient burst of ROS with maximal increase at 5-10 min after treatment. This ROS increase was inhibited by antioxidants, glutathione(GSH) and N-acetylcysteine(NAC). TGF-β1 induced protein tyrosine phosphorylation at 10 min after treatment, which was abolished by NAC, indicating that ROS mediates TGF-β1-induced tyrosine phosphorylation. Direct addition of H₂O₂ resulted in tyrosine phosphorylation of the same size protein. TGF-β1 treatment stimulated IL-6 gene expression and protein synthesis. Antioxidants including NAC, GSH, and catalase abolished TGF-β1-induced IL-6 gene expression, and direct H₂O₂ treatment induced IL-6 expression in a dose-dependent manner. Furthermore, NAC released the suppressive effects of TGF-β1 on HLF cell proliferation. These results suggest that TGF-β1 induces transient increase of intracellular H₂O₂ production, which turns on protein tyrosine kinase activation regulating downstream events of IL-6 gene expression or cell growth. In addition, there are growing evidences that antioxidant genes are involved in cytokine signaling and immune response. As a result to identify the regulatory proteins of thioredoxin(TRX), a murine homologue for human vitamin D3 up-regulated protein 1(hVDUP1) was identified from a yeast two-hybrid screen. Co-transfection into 293 cells and precipitation assays confirmed that mouse VDUP1(mVDUP1) bound to TRX, but it failed to bind to a Cys-32. and Cys-35 mutant TRX, suggesting the redox-active site is critical for binding. in VDUP1 was ubiquitously expressed in various tissues and located in the cytoplasm. Biochemical analysis showed that in VDUP1 inhibited the insulin reducing activity of TRX. When cells were treated with various stress stimuli such as H₂O₂ and heat shock, in VDUP1 was significantly induced.

Regulation of Cytokine Gene Expression : Regulation of IL-6 Expression in Multiple Myeloma

Choi, Inpyo,Kang, Hyung Sik,Pyum, Kwnag Ho 中央醫學社 1996 中央醫學 Vol.61 No.3

Cytokines are procduced by a variety of immune cells and non-immune-cells, and involved in many immune reactions and immune diseases. They are main mediators of the communication of immune cells, cellular and humoral immune reponses. So far, 15 different interleukines, chemokines, IFN, and TNF families have been cloned and characterized, but sits many other functions are yet to be determined. In T cell development, there are two different types of cytokines are involved. IL-12- in duces the development Th1 cells, which secret IFNr. Meanwhile, IL-4 induces the development of Th2 cells, which secret IL-4, IL-5, IL-6, and IL-10. Each cytokines has its own- receptor with very specific affinity. Cytokine receptors can deliver the signals into the cells, using different signaling molecules. Protein tyrosine kinases such as jak kinases are associated wioth receptors and involved in eartly steps of signal transduction. Several stat proteins, then, deliver the signals in to the necleus to activate the transcription machinery. Multiple myeloma(MM) is a disorder of B cell proliferation characterized by monoclonal proliferation of malignant plasma cells(myeloma cells) and marked suppression of all normal immunoglobulin synthesis1). Clinical features of MM appear infections2-4) . They are mainly due to malignant transformation of a single clone of plasma cells. The majority of myeloma cells are mostly located in the bone marrow(BM), since stromal cells present a variety of adhesion molecules and trap myeloma cells there, strongly suggesting that microenvironments within BM, where these cells receive the signals leading to proliferation, and terminal differentiation, are important5-7)BM stromal cells stimulate proliferation and differentiation of myeloma cells through cell-tocell interaction, and by secretion of soluble mediators, Thus, these cells are a major source of several cytokines, and play the important roles in the regulation of hematopoiesis and B cell malignancy. IL-6, previously known as B cell differentiation factor8-9), B cell stimulatory factor-2, 26 KD protein10), interferon ?211) hepato-cyte stimulatory factor12-13)and plasmacytoma hybridoma growth factor14), is a multifuntional cytokine that is produced by a variety types of cells, and acts on many kinds of target cells in immune, hematopoietic and inflammatory systems. Also, it has been reported that IL-6 was involved in the funal differentiation of B cells into immunoglobulin secreting cells9)14) , the expression of myelomoncytic antigens, activation of T cells, induction of acute phase protein synthesis in the liver cells12,13)and proliferation of some tumor cells15). IL 6 expression could be induced by inflammation, viral infection, and other cytokines such as IL-1 and TNF-?. Deregulation of its expression is related to the pathogenesis of various diseases, such as autoimmune diseases9)16)17) chronic inflammation, glomerulonephritis18), and plasma cell

Roles of ROS in cytokine-mediated signaling and immune regulation

Choi, Inpyo 이화여자대학교 세포신호전달연구센터 1999 고사리 세포신호전달 심포지움 Vol. No.1

To investigate the possible roles of reactive oxygen species(ROS) in transforming growth factor-β1(TGF-β1) signal transduction, quiescent human lung fibroblast(HLF) cells were stimulated with TGF-β1. TGF-β1 stimulation resulted in a transient burst of ROS with maximal increase at 10 min after treatment. This ROS increase was inhibited by antioxidants, NAC and GSH. TGF-β1 induced protein tyrosine phosphorylation at 10 min after treatment, which was abolished by NAC, indicating that ROS mediates TGF-β1-induced tyrosine phosphorylation. Also, direct addition of H₂O₂ resulted in tyrosine phosphorylation of the same size protein. In addition, TGF-β1 treatment stimulated IL-6 gene expression and protein synthesis in HLF cells. Antioxidants including NAC, GSH, and catalase abolished TGF-β1-induced IL-6 gene expression, and direct H₂O₂ treatment induced IL-6 expression in a dose-dependent manner. Genistein, an inhibitor of tyrosine kinase, inhibited TGF-β1-induced IL-6 gene expression, while it had no effect on ROS production. Finally, NAC released the suppressive effects of TGF-β1 on HLF cell proliferation. In addition, there are growing evidences that ROS is involved in apoptosis. To understand the roles of ROS in Fas-mediated apoptosis of multiple myeloma(MM) cells, the effects of antioxidants were tested. Fas-mediated apoptosis was further increased in the presence of antioxidants. Previous our study demonstrated that okadaic acid(OKA), inhibits IL-6-mediated growth of myeloma cells via reducing IL-6 production. OKA treatment increased Fas-mediated apoptosis and reduced intracellular ROS level in myeloma cells. To clarify the direct roles of PP2A in apoptosis and ROS production, the stably transfected cell lines, sense- or antisense-PP2A transfectants, were established. Intracellular ROS level was significantly decreased in antisense-PP2A transfectant, but increased in sense-PP2A transfectant compared with vector control. Concomitantly, Fas-mediated apoptosis was remarkably induced in antisense-PP2A transfectant, indicating that the suppression of PP2A increases the susceptibility to Fas-mediated apoptosis. In addition, spontaneous IL-6 production, was reduced in antisense-PP2A transfectant, while hydrogen peroxide also increased IL-6 expression. Taken together, these results indicate that PP2A is an essential factor for survival and growth of myeloma cells via regulating ROS and IL-6 production.

NDRG2 is one of novel intrinsic factors for regulation of lL-10 production in human myeloid cell

최승철,김광동,김종태,오상석,윤선영,송은영,이희구,조영경,최인표,임종석,김재화 Sookmyung Women's University Research Institute of 2010 여성과 건강 Vol.6 No.1

Distinctive bone regeneration of calvarial defects using biphasic calcium phosphate supplemented ultraviolet-crosslinked collagen membrane

Hong, Inpyo,Khalid, Alharthi Waleed,Pae, Hyung-Chul,Cha, Jae-Kook,Lee, Jung-Seok,Paik, Jeong-Won,Jung, Ui-Won,Choi, Seong-Ho Korean Academy of Periodontology 2020 Journal of Periodontal & Implant Science Vol.50 No.1

Purpose: To overcome several drawbacks of chemically-crosslinked collagen membranes, modification processes such as ultraviolet (UV) crosslinking and the addition of biphasic calcium phosphate (BCP) to collagen membranes have been introduced. This study evaluated the efficacy and biocompatibility of BCP-supplemented UV-crosslinked collagen membrane for guided bone regeneration (GBR) in a rabbit calvarial model. Methods: Four circular bone defects (diameter, 8 mm) were created in the calvarium of 10 rabbits. Each defect was randomly allocated to one of the following groups: 1) the sham control group (spontaneous healing); 2) the M group (defect coverage with a BCP-supplemented UV-crosslinked collagen membrane and no graft material); 3) the BG (defects filled with BCP particles without membrane coverage); and 4) the BG+M group (defects filled with BCP particles and covered with a BCP-supplemented UV-crosslinked collagen membrane in a conventional GBR procedure). At 2 and 8 weeks, rabbits were sacrificed, and experimental defects were investigated histologically and by micro-computed tomography (micro-CT). Results: In both micro-CT and histometric analyses, the BG and BG+M groups at both 2 and 8 weeks showed significantly higher new bone formation than the control group. On micro-CT, the new bone volume of the BG+M group (48.39±5.47 ㎣) was larger than that of the BG group (38.71±2.24 ㎣, P=0.032) at 8 weeks. Histologically, greater new bone area was observed in the BG+M group than in the BG or M groups. BCP-supplemented UV-crosslinked collagen membrane did not cause an abnormal cellular reaction and was stable until 8 weeks. Conclusions: Enhanced new bone formation in GBR can be achieved by simultaneously using bone graft material and a BCP-supplemented UV-crosslinked collagen membrane, which showed high biocompatibility and resistance to degradation, making it a biocompatible alternative to chemically-crosslinked collagen membranes.

NDRG2 is one of novel intrinsic factors for regulation of lL-10 production in human myeloid cell

최승철,김광동,김종태,오상석,윤선영,송은영,이희구,조영경,최인표,임종석,김재화 Sookmyung Women's University Research Institute of 2010 여성과 건강 Vol.6 No.1

Thioredoxin-interacting protein, hematopoietic stem cells, and hematopoiesis

Jung, Haiyoung,Choi, Inpyo CURRENT SCIENCE 2014 CURRENT OPINION IN HEMATOLOGY Vol.21 No.4

PURPOSE OF REVIEW: Reactive oxygen species (ROS) can regulate diverse signaling pathways and functions in hematopoietic cells. Thioredoxin-interacting protein (TXNIP) plays an important role in mammalian cells by inhibiting thioredoxin (TRX) under oxidative stress conditions. TXNIP is expressed in hematopoietic stem cells (HSCs), and its expression decreases as HSCs differentiate into precursor cells. However, this reduction in expression does not sufficiently explain the function of TXNIP in hematopoietic cells under oxidative stress conditions. Here, we review how ROS can regulate hematopoiesis by focusing on the function of TXNIP in hematopoietic cells under oxidative stress conditions. RECENT FINDINGS: Studies of Txnip mice have demonstrated an antioxidant function of TXNIP in hematopoietic cells or immune cells. This antioxidant function differs from the conventional pro-oxidant activity of TXNIP observed in other cell types under oxidative stress. The data suggest a context-dependent function of TXNIP under oxidative stress conditions and, in particular, a differential function of TXNIP in hematopoietic cells via its direct interaction with other redox regulatory proteins. SUMMARY: The regulation of ROS is important in determining cellular fate decisions. TXNIP acts as a negative regulator of TRX via direct interaction, and it increases the levels of ROS under oxidative stress. However, TXNIP has an antioxidant function in hematopoietic cells or immune cells, as ROS levels are elevated and induce apoptosis in Txnip hematopoietic cells. These results suggest that the amount of TXNIP is inversely associated with ROS levels, and the loss of TXNIP can increase ROS levels in immune cells or hematopoietic cells.