Biomedical subjects

Takashi Kuroha

Publications and source records attributed to Takashi Kuroha.

6 recordsLinked to original sources

PubMed2006

Characterization of GATA-1(+) hemangioblastic cells in the mouse embryo.

Hemangioblasts are thought to be one of the sources of hematopoietic progenitors, yet little is known about their localization and fate in the mouse embryo. We show here that a subset of cells co-expressing the hematopoietic marker GATA-1 and the endothelial marker VE-cadherin localize on the yolk sac blood islands at embryonic day 7.5. Clonal analysis demonstrated that GATA-1(+) cells isolated from E7.0-7.5 embryos include a common precursor for hematopoietic and endothelial cells. Moreover, this precursor possesses primitive and definitive hematopoietic bipotential. By using a transgenic complementation rescue approach, GATA-1(+) cell-derived progenitors were selectively restored in Runx1-deficient mice. In the rescued mice, definitive erythropoiesis was recovered but the rescued progenitors did not display multilineage hematopoiesis or intra-aortic hematopoietic clusters. These results provide evidence of the presence of GATA-1(+) hemangioblastic cells in the extra-embryonic region and also their functional contribution to hematopoiesis in the embryo.

Animals↗

PubMed2006

Dosage-dependent rescue of definitive nephrogenesis by a distant Gata3 enhancer.

Human GATA3 haploinsufficiency leads to HDR (hypoparathyroidism, deafness and renal dysplasia) syndrome, demonstrating that the development of a specific subset of organs in which this transcription factor is expressed is exquisitely sensitive to gene dosage. We previously showed that murine GATA-3 is essential for definitive kidney development, and that a large YAC transgene faithfully recapitulated GATA-3 expression in the urogenital system. Here we describe the localization and activity of a kidney enhancer (KE) located 113 kbp 5' to the Gata3 structural gene. When the KE was employed to direct renal system-specific GATA-3 transcription, the extent of cell autonomous kidney rescue in Gata3-deficient mice correlated with graded allelic expression of transgenic GATA-3. These data demonstrate that a single distant, tissue-specific enhancer can direct GATA-3 gene expression to confer all embryonic patterning information that is required for successful execution of metanephrogenesis, and that the dosage of GATA-3 required has a threshold between 50% and 70% of diploid activity.

Animals↗

PubMed2006

Gata3 participates in a complex transcriptional feedback network to regulate sympathoadrenal differentiation.

Gata3 mutant mice expire of noradrenergic deficiency by embryonic day (E) 11 and can be rescued pharmacologically or, as shown here, by restoring Gata3 function specifically in sympathoadrenal (SA) lineages using the human DBH promoter to direct Gata3 transgenic expression. In Gata3-null embryos, there was significant impairment of SA differentiation and increased apoptosis in adrenal chromaffin cells and sympathetic neurons. Additionally, mRNA analyses of purified chromaffin cells from Gata3 mutants show that levels of Mash1, Hand2 and Phox2b (postulated upstream regulators of Gata3) as well as terminally differentiated SA lineage products (tyrosine hydroxylase, Th, and dopamine beta-hydroxylase, Dbh) are markedly altered. However, SA lineage-specific restoration of Gata3 function in the Gata3 mutant background rescues the expression phenotypes of the downstream, as well as the putative upstream genes. These data not only underscore the hypothesis that Gata3 is essential for the differentiation and survival of SA cells, but also suggest that their differentiation is controlled by mutually reinforcing feedback transcriptional interactions between Gata3, Mash1, Hand2 and Phox2b in the SA lineage.

Adrenal Medulla↗

PubMed2004

Leukemogenesis caused by incapacitated GATA-1 function.

GATA-1 is essential for the development of erythroid and megakaryocytic lineages. We found that GATA-1 gene knockdown female (GATA-1.05/X) mice frequently develop a hematopoietic disorder resembling myelodysplastic syndrome that is characterized by the accumulation of progenitors expressing low levels of GATA-1. In this study, we demonstrate that GATA-1.05/X mice suffer from two distinct types of acute leukemia, an early-onset c-Kit-positive nonlymphoid leukemia and a late-onset B-lymphocytic leukemia. Since GATA-1 is an X chromosome gene, two types of hematopoietic cells reside within heterozygous GATA-1 knockdown mice, bearing either an active wild-type GATA-1 allele or an active mutant GATA-1.05 allele. In the hematopoietic progenitors with the latter allele, low-level GATA-1 expression is sufficient to support survival and proliferation but not differentiation, leading to the accumulation of progenitors that are easily targeted by oncogenic stimuli. Since such leukemia has not been observed in GATA-1-null/X mutant mice, we conclude that the residual GATA-1 activity in the knockdown mice contributes to the development of the malignancy. This de novo model recapitulates the acute crisis found in preleukemic conditions in humans.

Animals↗

PubMed2003

Therapeutic role of pericardiocentesis for acute necrotizing eosinophilic myocarditis with cardiac tamponade.

We describe a patient with acute necrotizing eosinophilic myocarditis who recovered rapidly after pericardial drainage and without corticosteroid therapy. The 25-year- old man was referred to our hospital with suspected acute myocardial infarction on the basis of severe epigastralgia, abnormal Q waves and ST elevation on electrocardiography, and an increase in cardiac enzymes. Echocardiography disclosed pericardial effusion that compressed the right ventricle, left ventricular dysfunction in conjunction with posterolateral hypokinesis, and a thickened ventricular wall but no mural thrombus. The eosinophil count in the peripheral blood was slightly increased. Coronary angiography showed normal arteries and thus prompted an endomyocardial biopsy. The patient was transferred to the intensive care unit with a clinical diagnosis of myocarditis associated with cardiac tamponade. Emergency pericardiocentesis relieved symptoms immediately. The cells in the pericardial effusion were mainly eosinophils; interleukin 5 and interleukin 13 levels were predominantly elevated, and the effusion was drained for 5 days. The biopsy specimen revealed necrotizing eosinophilic myocarditis. Left ventricular function recovered within a week without corticosteroid therapy. No relapse was observed as of 8 months after diagnosis.

Adult↗

PubMed2002

Effect of growth factors on ex vivo bone marrow cell expansion using three-dimensional matrix support.

To develop a culture system for bone marrow (BM) cell expansion, we examined the effect of growth factors (GFs) on the proliferation and differentiation of BM cells cultured in three-dimensional (3D) scaffolds of porous polyvinyl formal (PVF) resin. Murine BM cells were cultured for 2 weeks in the PVF resin or in culture dishes as a control, in the presence or absence of 4 GFs (erythropoietin, stem cell factor, interleukin [IL]-3, and IL-6). These GFs remarkably stimulated cell proliferation both in PVF and dish cultures. In addition, the PVF cultures showed enhanced cell proliferation in comparison with the corresponding dish cultures. Moreover, PVF cultures with GFs revealed the highest number of colony-forming units and the highest percentage of hematopoietic progenitor cells (HPCs) among all the cultures examined. Therefore, this 3D PVF culture system with GFs is considered as a potential alternative method for the ex vivo expansion of HPCs.

Animals↗