Shizuka Masaki

Mahidol University, Bangkok, Bangkok, Thailand

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Publications (3)5.27 Total impact

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    ABSTRACT: MicroRNAs (miRNAs) are negative regulators of gene expression that play an important role in hematopoiesis. Thalassemia, a defective globin synthesis leading to precipitate of excess unbound globins in red blood cell precursors, results in defective erythroid precursors and ineffective erythropoiesis. Expression pattern of miR-451, an erythroid-specific miRNA, was analyzed during differentiation of erythroid progenitors derived from normal and thalassemic peripheral blood CD34-positive cells, after 14 days of culture. A biphasic expression with transient up-regulation of miRNA-451 on day 3 of cultures was observed during thalassemic erythroid differentiation. In contrast, the expression pattern of the miR-451 in erythroid cells obtained from the other extravascular hemolytic anemia, i.e., hereditary spherocytosis patients showed no transient up-regulation of miR-451 on day 3 of cultures. Our results suggest that early erythroid progenitors in beta-thalassemia have a dysregulated miRNA-451 expression program, and analysis of microRNA is a relevant approach to determine abnormalities of erythropoiesis.
    Annals of Hematology 05/2010; 89(10):953-8. · 2.87 Impact Factor
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    ABSTRACT: microRNAs (miRNAs) are non-coding RNAs, and are negatively regulating the gene functions through translational repression or digesting mRNAs by targeting 3'-UTR in messenger RNAs (mRNAs). To clarify roles of miRNAs in normal and pathological erythropoiesis, we analyzed the expression of miR-451, miR-155, miR-221 in normal human erythroid colony forming cells (ECFCs) and circulating red blood cells using quantitative real-time polymerase chain reaction. Remarkable down-regulation of miR-155 (about 200-fold) and up-regulation of miR-451 (270-fold) were observed during 12 days of ECFC cultures. miR-221 was down-regulated moderately (20-fold). Since mature erythroid cells expressed miR-451 at high levels, we analyzed the content of miR-451 in fractionated peripheral blood cells obtained from normal subjects (n= 3), and found that the expression level of miR-451 in red blood cells was about 10(4)-fold more than in granulocytes and mononuclear cells. Analysis of packed red cells from normal subjects (n=3) and patients with hematological disorders (n=16), showed that there was no significant difference of the expression levels of miR-451 between normal and patients. In conclusion, expression profiles of miR-155 and miR-451 are stage-specific during normal erythropoiesis in which miR-155 is down-regulated and miR-451 is up-regulated. A high expression of miR-451 is specific to red blood cells among circulating blood cells. These observations suggest that an analysis of microRNAs is a new relevant approach to understand underlying mechanisms of hematological disorders.
    Rinsho byori. The Japanese journal of clinical pathology 01/2009; 56(12):1086-92.
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    ABSTRACT: To clarify the roles of microRNAs (miRNAs) in erythropoiesis, the expression of miR-155, miR-221, miR-223, and miR-451 were analyzed during the differentiation of purified normal human erythroid progenitors in a liquid culture system. Cells increased almost 500-fold in a number, and differentiated to benzidine-positive mature erythroblasts. Analyses of miRNA expression using the quantitative real-time polymerase chain reaction showed that the expression level of miR-155 decreased about 200-fold, and that the expression of miR-451 increased about 270-fold during 12 days of cultures. A moderate down-regulation of miR-221 and miR-223 was observed. MiR-451 was expressed in red blood cells about 10(4)-fold more than in granulocytes, obtained from normal human peripheral blood. These observations suggest that miR-155 and miR-451 are key molecules for normal erythroid differentiation, and that quantitative assays of the two miRNAs may be a relevant method for analyzing pathological erythropoiesis.
    Biochemical and Biophysical Research Communications 01/2008; 364(3):509-14. · 2.41 Impact Factor

Publication Stats

75 Citations
5.27 Total Impact Points


  • 2010
    • Mahidol University
      • Institute of Molecular Biosciences
      Bangkok, Bangkok, Thailand
  • 2008–2010
    • Kyushu University
      • Faculty of Medical Sciences
      Hukuoka, Fukuoka, Japan