Biomedical subjects

So-Youn Woo

Publications and source records attributed to So-Youn Woo.

5 recordsLinked to original sources

PubMed2003

CD40-mediated transcriptional regulation of the IL-6 gene in B lymphocytes: involvement of NF-kappa B, AP-1, and C/EBP.

Engagement of CD40 by its ligand CD154 induces IL-6 production by B lymphocytes. We previously reported that this IL-6 production is dependent upon binding of the adapter protein TNF receptor-associated factor 6 to the cytoplasmic domain of CD40, while binding of TNF receptor-associated factors 2 and 3 is dispensable, as is the activation-induced nuclear translocation of NF-kappa B. The present study was designed to characterize CD40-mediated transcriptional control of the IL-6 gene in B cells. CD40 engagement on B lymphocytes activated the IL-6 promoter, and mutations in the putative binding sites for AP-1 and C/EBP transcription factors reduced this activation. Interestingly, a mutation in the putative NF-kappa B binding site completely abrogated the basal promoter activity, thus also rendering the promoter unresponsive to CD40 stimulation, suggesting that this site is required for binding of NF-kappa B constitutively present in the nucleus of mature B cells. The expression of dominant negative Fos or C/EBP alpha proteins, which prevent binding of AP-1 or C/EBP complexes to DNA, also reduced CD40-mediated IL-6 gene expression. Furthermore, CD40 stimulation led to phosphorylation of c-Jun on its activation domain, implicating CD40-mediated Jun kinase activation in the transcriptional regulation of IL-6 production.

Animals↗

PubMed2003

In vitro differentiation of natural killer T cells from human cord blood CD34+ cells.

Natural killer T (NKT) cells are involved in innate immune defence and also in the regulation of adaptive immune responses. However, the development of NKT cells in vitro has not been fully characterized and culture conditions have not been fully optimized. In the present study, we found that an NKT cell fraction developed during the in vitro culture of cord blood (CB) CD34+ cells, and this was subsequently characterized both phenotypically and morphologically. CD34+ cells purified from 10 human CB were cultured in the presence of several cytokines and analysed by flow cytometry, light microscopy and electron microscopy. The NKT cell fraction, defined phenotypically (CD3+CD16+CD56+CD94+) as expressing the invariant T-cell receptor Valpha24 and Vbeta11, appeared in the CD56hi fractions. Intracytoplasmic staining demonstrated that interferon-gamma and interleukin 4 (IL-4) were detected in the CD56hi fractions. IL-15 was essential and, in combination with either flt3-ligand (FL) or stem cell factor (SCF), was sufficient to induce the development of NKT cells. The phenotype of the NKT cell fraction was CD45RO+CD45RA- and CD4+CD8alpha+. Morphologically, they were very large, with either round or oval nuclei, moderately condensed chromatins, voluminous weakly basophilic cytoplasm and various cytoplasmic granules such as dense core granules, multivesicular bodies, and intermediate form granules. When CD34+ cells purified from bone marrow (BM) were compared with those from CB, the latter were consistently more efficient at generating CD56hi NKT cell fractions. In conclusion, IL-15 in combination with FL and/or SCF can induce the differentiation of NKT cells from human CB CD34+ cells.

Antigens, CD↗

PubMed2002

Decrease in apoptosis and increase in polyploidization of megakaryocytes by stem cell factor during ex vivo expansion of human cord blood CD34+ cells using thrombopoietin.

Thrombopoietin (TPO) is widely used for ex vivo expansion of hematopoietic stem cells. Previously, we have reported that TPO induces a characteristic pattern of apoptosis, and the TPO-induced apoptosis is closely associated with megakaryocyte (MK) differentiation. In the present study, several cytokines, flt3-ligand, stem cell factor (SCF), interleukin-3 (IL-3), IL-6, IL-11, leukemia inhibitory factor, G-CSF, and erythropoietin, which are known to affect megakaryocytopoiesis, have been evaluated to elucidate their effects on the TPO-induced apoptosis. Measurement of apoptosis by flow cytometry revealed that only SCF absolutely reduced the TPO-induced apoptosis in MK fractions, particularly in the late phase of ex vivo expansion. Platelet production was demonstrated by electron microscopy in a later phase when SCF was added. Simultaneous measurement of DNA contents with immunophenotyping demonstrated a significant increase in polyploidization in the CD41+ cell fraction when cultured with SCF. These results suggested that SCF not only inhibited premature senescence but also enhanced maturation of the differentiating cells of MK lineage during ex vivo expansion using TPO.

Antigens, CD34↗

PubMed2002

Gene expression profile of megakaryocytes from human cord blood CD34(+) cells ex vivo expanded by thrombopoietin.

Previously, we investigated the process of megakaryocytopoiesis during ex vivo expansion of human cord blood (CB) CD34(+) cells using thrombopoietin (TPO) and found that megakaryocytopoiesis was closely associated with apoptosis. To understand megakaryocytopoiesis at the molecular level, we performed a microserial analysis of gene expression (microSAGE) in megakaryocytes (MKs) and nonmegakaryocytes (non-MKs) derived from human CB CD34(+) cells by ex vivo expansion using TPO, and a total of 38909 tags, representing 8976 unique genes, were identified. In MKs, many of the known genes, including coagulation factor VII, P-selectin (CD62P), pim-1, azurocidin, defensin, and CD48 were highly expressed; meanwhile, those genes encoding some small G proteins of the Ras family (Rab 7 and Rab 11A) and glutathione S transferase family (1, 4, A2, omega, and pi) showed lower expression levels in MKs. These gene expression profiles will be useful to understand megakaryocytopoiesis at the molecular level, including apoptosis and related signal transduction pathways.

Antigens, CD34↗

PubMed2002

Functional maturation of myeloid cells during in vitro differentiation from human cord blood CD34+ cells.

CD34+ cells purified from human cord blood were expanded in the presence of several cytokines. The cultured cells were assayed for myeloid effector functions, including phagocytic activity, respiratory burst and microbicidal activity. The results showed that phagocytic activity was observed as early as day 6, irrespective of the type of cytokines used. By contrast, respiratory burst and microbicidal activity peaked on day 15 and were dependent on the type of cytokines used. In particular, granulocyte-colony stimulating factor and interleukin-6 markedly enhanced respiratory burst and microbicidal activity.

Antigens, CD34↗