Shin'ya Ohmori

Publications (3)13.51 Total impact

• Article: The regulation of GATA factor expression is distinct between erythroid and mast cell lineages.

  Shin'ya Ohmori, Jun Takai, Yasushi Ishijima, Mikiko Suzuki, Takashi Moriguchi, Sjaak Philipsen, Masayuki Yamamoto, Kinuko Ohneda
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  ABSTRACT: The zinc finger transcription factors GATA1 and GATA2 participate in mast cell development. Although the expression of these factors is regulated in a cell-lineage-specific and differentiation-stage-specific manner, their regulation during mast cell development has not been clarified. Here, we show that the GATA2 mRNA level was significantly increased, while GATA1 levels were maintained at low levels during the differentiation of mast cells derived from mouse bone marrow (BMMCs). Unlike in erythroid cells, either forced expression or siRNA-mediated knock-down of GATA1 rarely affected GATA2 expression and vice versa in mast cells, indicating the absence of cross-regulation between Gata1 and Gata2 genes. Chromatin immunoprecipitation assays revealed that both GATA factors bound to most of the conserved GATA sites of Gata1 and Gata2 loci in BMMCs. However, the GATA1 hematopoietic enhancer (G1HE) of Gata1 gene, which is essential for GATA1 expression in erythroid and megakaryocytic lineages, was bound only weakly by both GATA factors in BMMCs. Furthermore, transgenic mouse reporter assays revealed that the G1HE is not essential for reporter expression in BMMCs and peritoneal mast cells. Collectively, these results demonstrate that the expression of GATA factors in mast cell is regulated in a quite distinct manner from that in erythroid cells.
  Molecular and cellular biology 09/2012; · 6.06 Impact Factor
• Article: GATA transcription factors are involved in IgE-dependent mast cell degranulation by enhancing the expression of phospholipase C-γ1.

  Yasushi Ishijima, Shin'ya Ohmori, Ayano Uenishi, Kinuko Ohneda
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  ABSTRACT: Mast cell degranulation is a dynamic, highly organized process involving numerous signaling molecules and enzymes. Although the molecular mechanisms underlying antigen-mediated mast cell degranulation have been studied intensively, little is known about the transcriptional control of this process. Here, we show that the hematopoietic transcription factors GATA1 and GATA2 are involved in mast cell degranulation through the control of phospholipase C-γ1 (PLC-γ1) expression. Knockdown of GATA1 and/or GATA2 by specific siRNA significantly reduced antigen-induced degranulation and Ca(2+) mobilization in the rat basophilic leukemia cell line RBL-2H3. RT-PCR analyses showed that PLC-γ1 expression was significantly decreased by this GATA factor repression. Other GATA factor targets, such as the previously reported α and β subunits of the high-affinity IgE receptor (FcεRI), were unaffected. Chromatin immunoprecipitation and luciferase reporter assays demonstrated that GATA factors directly activate PLC-γ1 gene transcription through a conserved GATA-binding motif that resides in the 5'-upstream sequence. Furthermore, we show evidence that the PLC-γ1 expression is regulated by GATA2 in mast cells derived from mouse bone marrow. These data indicate that PLC-γ1 is a target gene of GATA factors in mast cells and provide evidence that GATA1 and GATA2 control antigen-mediated mast cell degranulation by regulating the expression of PLC-γ1.
  Genes to Cells 03/2012; 17(4):285-301. · 2.68 Impact Factor
• Article: Characterization of a functional ZBP-89 binding site that mediates Gata1 gene expression during hematopoietic development.

  Kinuko Ohneda, Shin'ya Ohmori, Yasushi Ishijima, Mayu Nakano, Masayuki Yamamoto
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  ABSTRACT: GATA-1 is a lineage-restricted transcription factor that plays essential roles in hematopoietic development. The Gata1 gene hematopoietic enhancer allowed Gata1 reporter expression in erythroid cells and megakaryocytes of transgenic mice. The Gata1 hematopoietic enhancer activity is strictly dependent on a GATA site located in the 5' region of the enhancer. However, the importance of the GC-rich region adjacent to the 3'-end of this GATA site has been also suggested. In this study, we show that this GC-rich region contains five contiguous deoxyguanosine residues (G(5) string) that are bound by multiple nuclear proteins. Interestingly, deletion of one deoxyguanosine residue from the G(5) string (G(4) mutant) specifically eliminates binding to ZBP-89, a Krüppel-like transcription factor, but not to Sp3 and other binding factors. We demonstrate that GATA-1 and ZBP-89 occupy chromatin regions of the Gata1 enhancer and physically associate in vitro through zinc finger domains. Gel mobility shift assays and DNA affinity precipitation assays suggest that binding of ZBP-89 to this region is reduced in the absence of GATA-1 binding to the G1HE. Luciferase reporter assays demonstrate that ZBP-89 activates the Gata1 enhancer depending on the G(5) string sequence. Finally, transgenic mouse studies reveal that the G(4) mutation significantly reduced the reporter activity of the Gata1 hematopoietic regulatory domain encompassing an 8.5-kbp region of the Gata1 gene. These data provide compelling evidence that the G(5) string is necessary for Gata1 gene expression in vivo and ZBP-89 is the functional trans-acting factor for this cis-acting region.
  Journal of Biological Chemistry 10/2009; 284(44):30187-99. · 4.77 Impact Factor