转录因子GATA-1在造血系统中的作用(综述)

转录因子GATA-1为正常红细胞发育和分化成熟所必需。GATA-1的表达严格限制于造血细胞系,主要调控红系的增殖和分化,对巨核系、肥大细胞系及嗜酸性粒细胞系也起一定的作用。GATA-1参与自身启动子的正调节,而且GATA-1和PU.1可以通过交互作用抑制各自的功能;GATA-1与红系Kr櫣ppel样因子(EKLF)、FKLF-2、SCL、生长因子骨形态生成蛋白(BMP-4)及其他GATA转录因子之间存在相互调控作用。GATA-1可在急性非淋巴细胞性白血病等多种类型白血病中表达,它的表达还可影响急性髓性白血病的预后。GATA-1还与遗传性球形红细胞增多症、伴有严重贫血的多发性骨髓瘤的发病机制有关。     

Spleen colony-forming cell as common precursor for tissue mast cells and granulocytes

The haematopoietic stem cells which produce colonies in the spleen of irradiated mice (CFU-S) can differentiate into erythrocytes, granulocytes, megakaryocytes and B lymphocytes. Although mast cell precursors are known to be present in the bone marrow, spleen, fetal liver and peripheral blood of mice, the relationship between the mast cell precursor and CFU-S has remained unclear. We have now made use of mice of two mutant genotypes to determine whether or not the tissue mast cell is a progeny of CFU-S. Giant granules of beige (C57BL/6-bg/bg, Chediak-Higashi syndrome) mice can be used for identification of the origin of both tissue mast cells and granulocytes, and WBB6F1-W/Wv mice are useful recipients because they lack tissue mast cells owing to a defect in mast cell precursors. We injected the cells from a single spleen colony into each WBB6F1-W/Wv mouse and demonstrated directly that the tissue mast cell is a progeny of CFU-S.     

Stimulation of multipotential, erythroid and other murine haematopoietic progenitor cells by adherent cell lines in the absence of detectable multi-CSF (IL-3)

It is well established that murine multipotential and committed erythroid progenitor cells require the presence of a glycoprotein, termed multi-CSF (multi-colony-stimulating factor, IL-3) for clonal proliferation and differentiation in vitro. The initial proliferation of these cells can also be stimulated by two other glycoproteins, granulocyte-macrophage CSF (GM-CSF) and granulocyte CSF (G-CSF), although continued proliferation and differentiation requires the subsequent presence of multi-CSF. Here we report the stimulation of multipotential, erythroid and other haematopoietic progenitor cells by a number of adherent cell lines including a cloned bone marrow cell line (B.Ad). The positive cell lines, as feeder layers, exhibit colony-stimulating, erythropoietin-like and burst-promoting (BPA) activities. Optimal erythropoietic stimulation by the B.Ad line requires close cell-cell contact. The cell lines also support the in vitro clonal growth of multipotential colony-forming cells and progenitors of six other haematopoietic lineages. The biological activities observed seem not to be mediated by known multipotential or erythroid colony-stimulating factors (multi-CSF, IL-3, MCGF, HCGF, PSF, BPA).     

Increased gamma-globin expression in a nondeletion HPFH mediated by an erythroid-specific DNA-binding factor

In man, a shift from gamma- to beta-globin gene expression in erythroblasts underlies a switch from fetal to adult haemoglobin during development. In hereditary persistence of fetal haemoglobin (HPFH), inappropriately high gamma-globin expression in adult life is associated with deletions in the beta-globin cluster or with single-base changes upstream of the gamma-globin genes. To account for enhanced gamma-gene expression in HPFH of the non-deletion type, we tested the nuclear proteins of human erythroleukaemia cells that bind gamma-promoter sequences in vitro by correlating specific mutations in their binding sites with promoter activity. An erythroid-specific factor (GF-1) binds as a single molecule to the -195 to -170 region and contacts two TATCT(AGATA) motifs, but not the conserved octamer (ATGCAAAT) that separates them. We observe that a single change (at -175, T----C) found in HPFH leads to increased promoter activity only in erythroid cells. This effect is mediated by GF-1, the human counterpart of the chicken erythroid factor Eryf 1. The form of HPFH we studied here is an inherited disorder which can be ascribed to the action of a cell-specific DNA-binding factor on a mutant promoter.     

Long-term culture of murine erythropoietic progenitor cells in the absence of an adherent layer

Replication of multipotential stem cells in long-term murine bone marrow cell culture is known to depend on the development of an adherent stromal cell layer. In these conditions, restricted haematopoietic progenitor cells have also been generated for up to several months1-3. However, maturation is observed only in the granulocyte/macrophage and megakaryocyte lineages; erythropoiesis appears to be blocked at the earliest burst-forming unit (BFU-E) stage. Addition of exogenous erythropoietin (Epo) or anaemic mouse serum results in full erythropoietic maturation, but it is transient. We describe here a culture system in which production of erythropoietic progenitor cells can be maintained for over 6 months in the absence of an adherent stromal layer and in the absence of added Epo, but in the presence of pokeweed mitogen-stimulated spleen cell conditioned medium (PWSCM). The data indicate that restricted erythroid progenitor cells exist which are capable of extensive self-renewal.     

Developmental regulation of a cloned adult beta-globin gene in transgenic mice

At different stages of mammalian development, distinct embryonic, fetal and adult haemoglobins are synthesized in erythroid cells, a process termed haemoglobin switching. The cellular and molecular mechanisms controlling haemoglobin switching have been intensively studied, but remain poorly understood. To study the developmental regulation of globin gene expression, we have produced transgenic mice in which cloned globin genes are present in erythroid cells throughout development. Recently, we reported that adult mice in several transgenic lines carrying a hybrid mouse/human adult beta-globin gene, expressed the gene in a correct tissue-specific manner. This finding raised the question of whether an exogenous globin gene could also be subject to appropriate stage-specific regulation. We report here that the hybrid beta-globin gene, like the endogenous adult beta-globin genes, is inactive in yolk sac-derived embryonic erythroid cells and is expressed for the first time in fetal liver erythroid cells. Our results indicate that a stage-specific pattern of expression can be conferred by cis-acting regulatory elements closely linked to an adult beta-globin gene. They also suggest that the embryonic and adult beta-globin genes in the mouse are activated (or repressed) by distinct trans-acting regulatory factors present in embryonic, fetal and adult erythroid cells.     

Human cardiovascular progenitor cells develop from a KDR+ embryonic-stem-cell-derived population

The functional heart is comprised of distinct mesoderm-derived lineages including cardiomyocytes, endothelial cells and vascular smooth muscle cells. Studies in the mouse embryo and the mouse embryonic stem cell differentiation model have provided evidence indicating that these three lineages develop from a common Flk-1(+) (kinase insert domain protein receptor, also known as Kdr) cardiovascular progenitor that represents one of the earliest stages in mesoderm specification to the cardiovascular lineages. To determine whether a comparable progenitor is present during human cardiogenesis, we analysed the development of the cardiovascular lineages in human embryonic stem cell differentiation cultures. Here we show that after induction with combinations of activin A, bone morphogenetic protein 4 (BMP4), basic fibroblast growth factor (bFGF, also known as FGF2), vascular endothelial growth factor (VEGF, also known as VEGFA) and dickkopf homolog 1 (DKK1) in serum-free media, human embryonic-stem-cell-derived embryoid bodies generate a KDR(low)/C-KIT(CD117)(neg) population that displays cardiac, endothelial and vascular smooth muscle potential in vitro and, after transplantation, in vivo. When plated in monolayer cultures, these KDR(low)/C-KIT(neg) cells differentiate to generate populations consisting of greater than 50% contracting cardiomyocytes. Populations derived from the KDR(low)/C-KIT(neg) fraction give rise to colonies that contain all three lineages when plated in methylcellulose cultures. Results from limiting dilution studies and cell-mixing experiments support the interpretation that these colonies are clones, indicating that they develop from a cardiovascular colony-forming cell. Together, these findings identify a human cardiovascular progenitor that defines one of the earliest stages of human cardiac development.     

转录因子GATA—1基因在白血病中的表达

转录因子ＧＡＴＡ家族在造血细胞的正常发育中起着重要的作用。利用聚合酶链反应方法分析了１１６例各种白血病中红系统特异转录因子ＧＡＴＡ－１的表达情况。ＡＮＬＬ、ＣＭＬ、Ｃ－ＡＬＬ和ＣＬＬ中的表达率分别为４３．７５％、８８．２４％、１４．２９％和３３．３３％；３例Ｔ－ＡＬＬ均不表达该基因。     

Cloning of cDNA for the major DNA-binding protein of the erythroid lineage through expression in mammalian cells

Genes expressed in erythroid cells contain binding sites for a cell-specific factor believed to be an important regulator for this haematopoietic lineage. Using high-level transient expression in mammalian cells, we have identified complementary DNA encoding the murine protein. The factor, a new member of the zinc-finger family of DNA-binding proteins, is restricted to erythroid cells at the level of RNA expression and is closely homologous between mouse and man.     

Receptors for B-cell stimulatory factor-1 expressed on cells of haematopoietic lineage

B-cell stimulatory factor-1 (BSF-1) is a T-cell product of relative molecular mass 20,000 (Mr, 20K) initially described as a cofactor required for DNA synthesis by resting mouse B cells stimulated with low concentrations of anti-IgM antibodies. It acts on resting B cells to enhance the expression of class II major histocompatibility complex (MHC) molecules, to prepare these cells to respond more promptly to subsequent stimuli, such as anti-IgM antibodies, and causes the secretion of IgG1 and IgE by B cells stimulated with lipopolysaccharide (LPS). BSF-1 has been shown to stimulate T cell lines, resting T cells and some mast cell lines. Recently, the designation interleukin-4 (IL-4) has been suggested for BSF-1. We report here the existence of high-affinity cell-surface receptors specific for BSF-1 on both B and T lymphocytes, and on cells of several other haematopoietic lineages, including mast cell, macrophage and undifferentiated haematopoietic cell lines. Resting B and T lymphocytes express receptors, which increase in number upon activation of B cells with LPS or anti-IgM, and of T cells with concanavalin A. Cross-linking of 125I-labelled-BSF-1 to its receptors creates a complex of Mr approximately 80,000.