Biomedical subjects

Miyuki Ito

Publications and source records attributed to Miyuki Ito.

7 recordsLinked to original sources

PubMed2006

Comprehensive analysis of myeloid lineage conversion using mice expressing an inducible form of C/EBP alpha.

CCAAT/enhancer-binding protein (C/EBP) alpha is a critical regulator for early myeloid differentiation. Although C/EBPalpha has been shown to convert B cells into myeloid lineage, precise roles of C/EBPalpha in various hematopoietic progenitors and stem cells still remain obscure. To examine the consequence of C/EBPalpha activation in various progenitors and to address the underlying mechanism of lineage conversion in detail, we established transgenic mice expressing a conditional form of C/EBPalpha. Using these mice, we show that megakaryocyte/erythroid progenitors (MEPs) and common lymphoid progenitors (CLPs) could be redirected to functional macrophages in vitro by a short-term activation of C/EBPalpha, and the conversion occurred clonally through biphenotypic intermediate cells. Moreover, in vivo activation of C/EBPalpha in mice led to the increase of mature granulocytes and myeloid progenitors with a concomitant decrease of hematopoietic stem cells and nonmyeloid progenitors. Our study reveals that C/EBPalpha can activate the latent myeloid differentiation program of MEP and CLP and shows that its global activation affects multilineage homeostasis in vivo.

Animals↗

PubMed2005

Immune suppressor factor confers stromal cell line with enhanced supporting activity for hematopoietic stem cells.

Immune suppressor factor (ISF) is a subunit of the vacuolar ATPase proton pump. We earlier identified a short form of ISF (ShIF) as a stroma-derived factor that supports cytokine-independent growth of mutant Ba/F3 cells. Here, we report that ISF/ShIF supports self-renewal and expansion of primary hematopoietic stem cells (HSCs). Co-culture of murine bone marrow cells with a stromal cell line overexpressing ISF or ShIF (MS10/ISF or MS10/ShIF) not only enhanced their colony-forming activity and the numbers of long-term culture initiating cells, but also maintained the competitive repopulating activity of HSC. This stem cell supporting activity depended on the proton-transfer function of ISF/ShIF. Gene expression analysis of ISF/ShIF-transfected cell lines revealed down-regulation of secreted frizzled-related protein-1 and tissue inhibitor of metalloproteinase-3, and the restoration of their expressions in MS10/ISF cells partially reversed its enhanced LTC-IC supporting activity to a normal level. These results suggest that ISF/ShIF confers stromal cells with enhanced supporting activities for HSCs by modulating Wnt-activity and the extracellular matrix.

Animals↗

PubMed2004

E1AF/PEA3 reduces the invasiveness of SiHa cervical cancer cells by activating serine proteinase inhibitor squamous cell carcinoma antigen.

E1AF/PEA3, a member of the Ets family of transcription factors, is associated with the malignant characteristics of cancer cells. The initial aim of our study was to test whether the invasiveness of SiHa cervical cancer cells could be diminished by transfection with antisense E1AF. Using an in vitro invasion assay in which cells penetrate a layer of Matrigel, we found that this was not the case; indeed, the invasiveness of the transfectants was enhanced. To better understand the mechanism of this enhancement, we used the cDNA microarray technique to search for genes whose expression was altered in the antisense E1AF-transfected SiHa cells. Among several genes affected, we found that expression of squamous cell carcinoma antigen (SCCA), a member of the ovalbumin serine proteinase inhibitor family, was significantly reduced. Forced expression of E1AF enabled activation of SCCA expression, and Luciferase reporter assays revealed that E1AF activates the SCCA promoter. Introduction of antisense SCCA into SiHa cells inhibited production of SCCA protein and markedly increased the invasiveness of the cells. Taken together, these results suggest that E1AF suppresses the invasiveness of SiHa cervical cancer cells through transcriptional activation of the SCCA serine proteinase inhibitor gene.

Adenovirus E1A Proteins↗

PubMed2004

Expression of cell surface Lewis X and Y antigens and FUT4 mRNA is increased in Jurkat cells undergoing apoptosis.

Cell surface molecules undergo specific changes during apoptosis, including the expression of phosphatidylserine (PS) and some proteins and alterations in sugar chains. Among the various sugar chains on the cell surface, Lewis X (Le(X)) and Lewis Y (Le(Y)) antigens are key determinants for a variety of biological processes. We studied the changes in Le(X) and Le(Y) expression in Jurkat cells, a human T cell line, during apoptosis. Flow cytometry showed that Le(X) and Le(Y) antigen expression was enhanced on the cell surface during apoptosis induced by anti-Fas antibody. To clarify the mechanism of enhanced Le(X) and Le(Y) expression, we assessed the expression levels of fucosyltransferase (FUT1, 2, 3-5-6, 4, and 9) mRNAs that are predominantly expressed in Jurkat cells and which are considered to form Le(X) and Le(Y). The expression of FUT4 mRNA was up-regulated after exposing cells to anti-Fas antibody. Moreover, the increase in Le(X) and Le(Y) antigen levels was significantly suppressed by caspase 3 or 8 inhibitors. These results indicated that the induction of FUT (mainly FUT4), the gene expression of which is mediated by signals downstream of caspase 3, increases Le(X) and Le(Y) expression in apoptotic cells.

Antibodies↗

PubMed2004

Mechanical force analysis of peptide interactions using atomic force microscopy.

Some peptides have previously been reported to bind low molecular weight chemicals. One such peptide with the amino acid sequence His-Ala-Ser-Tyr-Ser was selectively screened from a phage library and bound to a cationic porphyrin, 5,10,15,20-tetrakis(N-methylpyridinium-4-yl)-21H,23H-porphine (TMpyP), with a binding constant of 10(5) M(-1) (J. Kawakami, T. Kitano, and N. Sugimoto, Chemical Communications, 1999, pp. 1765-1766). The proposed binding was due to pi-electron stacking from two aromatic amino acids of histidine and tyrosine. In this study, the weak interactions between TMpyP and the peptide were further investigated by force curve analysis using atomic force microscopy (AFM). The mechanical force required to unbind the peptide-porphyrin complex was measured by vertical movement of the AFM tip. Peptide self-assembled monolayers were formed on both a gold-coated mica substrate and a gold-coated AFM tip. The TMpyPs could bind between the two peptide layers when the peptide-immobilized AFM tip contacted the peptide-immobilized substrate in solution containing TMpyP. In the retracting process a force that ruptured the interaction between TMpyPs and peptides was observed. The unbinding force values correlated to the concentration of TMpyP. A detection limit of 100 ng/mL porphyrin was obtained for the force measurement, and was similar to surface plasmon resonance sensor detection limits. Furthermore, we calculated the product of the observed force and the length of the molecular elongation to determine the work required to unbind the complexes. The obtained values of unbinding work were in a reasonable range compared to the binding energy of porphyrin-peptide.

Biomechanical Phenomena↗

PubMed2004

[Effect of breast composition on patient exposure in mammography].

Software for the estimation of patient exposure from mammography has been developed. Because it adopts average glandular dose, the estimation of patient exposure must take advantage of D(gN) (average glandular dose per unit entrance skin exposure). D(gN) depends on X-ray quality, compressed breast thickness, and breast composition. The software that was previously reported required information about breast composition. However, the new software that estimates breast composition uses a phantom with known breast composition to estimate average glandular dose and entrance surface dose. The authors were able to calculate average glandular dose that takes account of breast composition using this software. In addition, in a comparison with the mammogram in terms of the classification of mammary gland substance, the software showed high precision in terms of agreement. This software has sufficient utility because only the mammographic conditions are entered, and patient exposure can be easily estimated. Moreover, the half-value layer, incident exposure in air, D(gN), and breast composition can be specifically calculated.

Breast↗

PubMed2002

Involvement of p27(KIP1) degradation by Skp2 in the regulation of proliferation in response to wounding of corneal epithelium.

PURPOSE: To examine the expression of the p27(KIP1)in the normal and epithelial-scraped cornea and whether degradation of p27(KIP1)by Skp2 is involved in the regulation of cell proliferation in response to wounding of the corneal epithelium. METHODS: C57Bl6, p27(KIP1-/-), Skp2(-/-), and Skp2(-/-)/p27(KIP1-/-) double-knockout mice were examined. Normal and epithelial-scraped corneas were analyzed by immunocytochemistry using anti-p27(KIP1) antibody. Cells in the S phase of DNA synthesis were analyzed by immunocytochemistry using anti-bromodeoxyuridine (BrdU) antibody. RESULTS: The p27(KIP1) was expressed in basal cells of the central and peripheral region of the cornea and limbus. This expression was not detected 24 hours after the epithelial scraping, when there were many cells in the S phase of DNA synthesis in the corneal epithelium. There were no obvious differences in the thickness and anti-BrdU staining in the corneal epithelium of p27(KIP1-/-) mice from that of control animals. Twenty-four hours after epithelial scraping in the Skp2(-/-) mice, the corneal epithelium was thinner than in wild-type mice and had many p27(KIP1)-positive cells and few BrdU-positive cells. In contrast, 24 hours after epithelial scraping in the Skp2(-/-)/p27(KIP1)(-/-) double-knockout mice, the corneal epithelium was as thick as in wild-type mice and had many BrdU-positive cells. CONCLUSIONS: These results suggest that degradation of p27(KIP1) by Skp2 is involved in the regulation of cell proliferation in response to wounding of the corneal epithelium.

Animals↗