Knock-in mutation of transcription factor GATA-3 into the GATA-1 locus: partial rescue of GATA-1 loss of function in erythroid cells

Transcription factors of the GATA-family are essential for proper development of diverse tissues or cell types. GATA-1 is required for differentiation of two hematopoietic lineages (red blood cells and megakaryocytes), whereas GATA-3 is essential for T-cell development. Functional studies suggest that many properties of the GATA-family of proteins are shared and largely interchangeable. To test whether the function of GATA-1 in erythroid differentiation can be replaced by another GATA-factor, we generated a knock-in mutation of the GATA-1 locus in which GATA-3 cDNA was introduced by gene targeting. Mutant embryos (designated G1G3ki), though embryonic lethal, exhibit partial rescue, characterized by increased survival of erythroid precursor cells and improved hemoglobin production. The basis for the incomplete extent of rescue is likely to be complex, but may be accounted for, in part, by insufficient accumulation of GATA-3 protein (compared with the normal level of GATA-1). Our findings suggest that GATA-3 protein is functional when expressed in an erythroid environment and is competent to act on at least a subset of erythroid-expressed target genes in vivo.

Characterization of cis-regulatory elements and nuclear factors conferring Th2-specific expression of the IL-5 gene: a role for a GATA-binding protein

Expression of the IL-5 gene is restricted to the Th2 subset of helper T cells. We have previously defined four cis-regulatory elements of the IL-5 promoter responding to PMA and cAMP in EL-4 cells. We now report that the 1.2-kb region of the IL-5 promoter directs expression of the IL-5 gene in a Th2 clone but not a Th1 clone, indicating that transcription from the IL-5 promoter is Th2 specific. For the functioning of the IL-5 promoter in a Th2 clone, IL-5C and IL-5CLE0 were critical. IL-5CLE0 interacted with both constitutive and inducible nuclear factors (designated NFIL-5CLE0), which existed in both Th1 and Th2 clones, whereas IL-5C interacted with a constitutive nuclear factor (designated NFIL-5C), which was found only in Th2 but not in Th1 clones. Th2 specificity of NFIL-5C was also confirmed using in vitro-differentiated Th1 and Th2 cells derived from TCR-transgenic mice. The sequence for NFIL-5C binding bears homology with GATA-binding sites. The NFIL-5C complex was supershifted by an anti-GATA-3 Ab and inhibited by an oligonucleotide containing GATA-binding sites. We showed preferential expression of GATA-3 in Th2 cells. Finally, we demonstrated that in vitro-translated GATA-3 bound to IL-5C and overexpression of GATA-3 augmented stimulation-dependent IL-5 promoter activity in EL-4 cells. Taken together, our results provide evidence that GATA-related factors may be involved in Th2-specific expression of the IL-5 gene.

Blood-borne seeding by hematopoietic and endothelial precursors from the allantois

Until now the allantois has not been considered as a hematopoietic organ. Here we report experimental evidence demonstrating the in situ emergence of both hematopoietic and endothelial precursors in the avian allantoic bud. When the prevascularized allantoic bud from a quail embryo was grafted in the coelom of a chicken host, hematopoietic and endothelial cells later were found in the bone marrow of the host. Because the graft was located at a distance from the limb bud, these cells could reach the bone marrow only by the circulatory pathway. This blood-borne seeding may be accomplished by distinct hematopoietic and endothelial precursors, or by hemangioblasts, the postulated common precursors of these two lineages; we consider the latter interpretation more likely. We also show by reverse transcription-PCR that the allantois region expresses very early the GATA genes involved in hematopoiesis and some beta-globin chain genes.

Analysis of interactions between huGATA-3 transcription factor and three GATA regulatory elements of HIV-1 long terminal repeat, by surface plasmon resonance

Relative affinities of transcriptional regulatory elements for their respective factor have been essentially studied by bandshift analysis. Here we report a real-time study of factor/DNA interactions using a surface plasmon resonance approach and further characterization of recovered proteins involved in this interaction. For this purpose, human GATA-3, either recombinant or in nuclear extracts, and three natural GATA elements of the HIV-1 long terminal repeat (sites 1, 2, and 3) were chosen, in which only site 2 is a noncanonical GATA site. Direct analysis of sensorgrams, with recombinant huGATA-3, allowed the comparison of association and dissociation profiles of the three DNA regions and their ranking according to their relative affinities. This result, confirmed by competitions with each GATA site, demonstrated the higher relative affinity (at least sevenfold) of site 3. Interactions between the canonical and unique GATA site 3 and nuclear extracts were also studied in real time and provided information on its association and dissociation rates for native huGATA-3. Finally, recovered protein was identified as genuine huGATA-3 by SDS-PAGE, Western blotting, and bandshift assays.

Transcription factor GATA-3 is differentially expressed in murine Th1 and Th2 cells and controls Th2-specific expression of the interleukin-5 gene

Interleukin-5 (IL-5), which is produced by CD4(+) T helper 2 (Th2) cells, but not by Th1 cells, plays a key role in the development of eosinophilia in asthma. Despite increasing evidence that the outcome of many diseases is determined by the ratio of the two subsets of CD4(+) T helper cells, Th1 and Th2, the molecular basis for Th1- and Th2-specific gene expression remains to be elucidated. We previously established a critical role for the transcription factor GATA-3 in IL-5 promoter activation in EL-4 cells, which express both Th1- and Th2-type cytokines. Our studies reported here demonstrate that GATA-3 is critical for expression of the IL-5 gene in bona fide Th2 cells. Whereas mutations in the GATA-3 site abolished antigen- or cAMP-stimulated IL-5 promoter activation in Th2 cells, ectopic expression of GATA-3 in Th1 cells or in a non-lymphoid, non-IL-5-producing cell line activated the IL-5 promoter. During the differentiation of naive CD4(+) T cells isolated from T cell receptor transgenic mice, GATA-3 gene expression was up-regulated in developing Th2 cells, but was down-regulated in Th1 cells, and antigen- or cAMP-activated Th2 cells (but not Th1 cells) expressed the GATA-3 protein. Thus, GATA-3 may play an important role in the balance between Th1 and Th2 subsets in immune responses. Inhibition of GATA-3 activity has therapeutic potential in the treatment of asthma and other hypereosinophilic diseases.

The proximal promoter region of the gene encoding human 17beta-hydroxysteroid dehydrogenase type 1 contains GATA, AP-2, and Sp1 response elements: analysis of promoter function in choriocarcinoma cells

The 5'-flanking region from -78 to +9 in the HSD17B1 gene serves as a promoter, and an HSD17B1 silencer element is located in position -113 to -78. In the present studies, we have characterized three regulatory elements in the proximal 5'-flanking regions of the gene, using electrophoretic mobility shift assays and reporter gene analysis. First, nuclear factors recognized by antibodies against Sp1 and Sp3 were found to bind the Sp1 motif in the region from -52 to -43. Mutation of the Sp1-binding site decreased the promoter activity to 30% in JEG-3 cells and to 60% in JAR cells, suggesting that binding to the Sp1 motif has a substantial role in the complete functioning of the HSD17B1 promoter. Second, the binding of AP-2 to its motif in the region from -62 to -53 led to reduced binding of Sp1 and Sp3, and furthermore, mutation of the AP-2 element increased promoter activity to 260% in JEG-3 cells. The data thus implied that AP-2 can repress the function of the HSD17B1 promoter by preventing binding to the Sp1 motif. Finally, GATA factors, GATA-3 in particular, were demonstrated to bind their cognate sequence in the HSD17B1 silencer region, and mutations introduced into the GATA-binding site increased transcriptional activity to the level seen in constructs not containing the silencer element. Thus, GATA-3 seems to prevent transcription in the constructs, and hence, the GATA motif also may operate as a negative control element for HSD17B1 transcription.

Temporal and spatial control of murine GATA-3 transcription by promoter-proximal regulatory elements

GATA-3 is expressed in a temporally dynamic manner and fulfills vital functions during vertebrate fetal development. Homozygous mGATA-3 mutant embryos die at midgestation, thus complicating the analysis of its contribution to the development of specific cell fates in the many tissues where it is expressed during embryogenesis. We show here that the elements controlling GATA-3 regulation can be precisely refined, using transgenic mice, to discrete cis-acting domains: within 6 kb surrounding the transcriptional initiation site, separate sequences were found to control the expression of mGATA-3 in early muscle masses, in a subset of PNS neurons, in the genital tubercle, and in the branchial arches. The branchial arch regulatory element is particularly robust and was refined to a discrete enhancer sequence lying between nt -2832 and -2462 from the transcription initiation site. The enhancer contains potential binding sites for many well-characterized transcription factors, suggesting that mGATA-3 transcriptional activity may be regulated by these proteins (or related family members) in the mesenchyme of the arches that contribute to formation of the jaw. These studies show that discrete regulatory elements required for the elaboration of complex developmental programs can be individually localized, suggesting that the developmentally transient expression of individual transcription factors collaboratively contributes to the temporal and spatial pattern of cellular differentiation leading to the formation of adult anatomy.

The transcription factor GATA-3 is necessary and sufficient for Th2 cytokine gene expression in CD4 T cells

CD4 T cells potentiate the inflammatory or humoral immune response through the action of Th1 and Th2 cells, respectively. The molecular basis of the differentiation of these cells from naive T cell precursors is, however, unclear. We found that GATA-3 was selectively expressed in Th2 cells. GATA-3 is expressed at a high level in naive, freshly activated T cells and Th2 lineage cells, but subsides to a minimal level in Th1 lineage cells as naive cells commit to their Th subset. Antisense GATA-3 inhibited the expression of all Th2 cytokine genes in the Th2 clone D10. GATA-3 directly activated an IL-4 promoter-luciferase reporter gene in M12 cells. In transgenic mice, elevated GATA-3 in CD4 T cells caused Th2 cytokine gene expression in developing Th1 cells. Thus, GATA-3 is necessary and sufficient for Th2 cytokine gene expression.

The N-terminal fingers of chicken GATA-2 and GATA-3 are independent sequence-specific DNA binding domains

The GATA family of vertebrate DNA binding regulatory proteins are expressed in diverse tissues and at different times of development. However, the DNA binding regions of these proteins possess considerable homology and recognize a rather similar range of DNA sequence motifs. DNA binding is mediated through two domains, each containing a zinc finger. Previous results have led to the conclusion that although in some cases the N-terminal finger can contribute to specificity and strength of binding, it does not bind independently, whereas the C-terminal finger is both necessary and sufficient for binding. Here we show that although this is true for the N-terminal finger of GATA-1, those of GATA-2 and GATA-3 are capable of strong independent binding with a preference for the motif GATC. Binding requires the presence of two basic regions located on either side of the N-terminal finger. The absence of one of these near the GATA-1 N-terminal finger probably accounts for its inability to bind. The combination of a single finger and two basic regions is a new variant of a motif that has been previously found in the binding domains of other finger proteins. Our results suggest that the DNA binding properties of the N-terminal finger may help distinguish GATA-2 and GATA-3 from GATA-1 and the other GATA family members in their selective regulatory roles in vivo.

Of the GATA-binding proteins, only GATA-4 selectively regulates the human IL-5 gene promoter in IL-5 producing cells which express multiple GATA-binding proteins

Interleukin-5 (IL-5) is produced by T lymphocytes and known to support B cell growth and eosinophilic differentiation of the progenitor cells. Using ATL-16T cells which express IL-5 mRNA, we have identified a region, within the human IL-5 gene promoter, that regulates IL-5 gene transcription. This cis-acting sequence contains the core binding motif, (A/T)GATA(A/G), for GATA-binding family proteins and thus suggests the involvement of these family members. In this report, we describe the cloning of human GATA-4 (hGATA-4) and show that hGATA-4 selectively interacts with the -70 GATA site within the IL-5 proximal promoter region. By promoter deletion and mutation analyses, we established this region as a positive regulatory element. Cotransfection experiments revealed that both hGATA-4 and PMA/A23187 stimulation are necessary for the IL-5 promoter activation. The requirement of another regulatory element called CLE0, which lies downstream of the -70 GATA site, was also demonstrated. ATL-16T cells express mRNA of three GATA-binding proteins, hGATA-2, hGATA-3 and hGATA-4, and each of them has a potential to bind to the consensus (A/T)GATA(G/ A) motif. However, using ATL-16T nuclear extract, we demonstrated that GATA-4 is the only GATA-binding protein that forms specific DNA-protein complex with the -70 GATA site. The electrophoretic mobility shift assay with extracts of COS cells expressing GATA-binding proteins showed that GATA-4 has the highest binding affinity to the -70 GATA site among the three GATA-binding proteins. When the transactivation ability was compared among the three, GATA-4 showed the highest activity. These results demonstrate the selective role of GATA-4 in the transcriptional regulation of the IL-5 gene in a circumstance where multiple members of the GATA-binding proteins are expressed.

Expression of GATA transcription factors in myelogenous and lymphoblastic leukemia cells

In the hematopoietic lineage, the transcription factors GATA-1 and GATA-2 show restricted and largely overlapping expression profiles, but GATA-2 is uniquely expressed in early hematopoietic progenitors. GATA-3 is found exclusively in T cells of hematopoietic lineage. To clarify whether these expression profiles are preserved or changed during the development of malignancies, we analyzed the expression of GATA factors in the blasts from leukemic children. A total of 18 myelogenous leukemia and 24 lymphoblastic leukemia (ALL) cases were investigated. In the majority of the former cases, GATA-2 mRNA expression and the expression of CD34 and c-kit antigens on leukemic cells were demonstrated. In contrast, GATA-2 mRNA and c-kit antigen could not be detected in CD34-positive cells from ALL patients. GATA-3 mRNA was expressed in all T-ALL cases, but not in any precursor B-ALL. These findings suggest that down-regulation of GATA-2 and expression of GATA-3 are important events for the commitment of cells to lymphoid and T cell lineage, respectively. The expression profiles of GATA factors in leukemic cells are generally consistent with those in their normal counterparts, and thus provide a useful tool to determine the lineage commitment of unclassified leukemia.

Regulation of aquaporin-2 gene transcription by GATA-3. off

To evaluate the functional role of GATA motifs in the 5'-flanking region of a kidney-specific AQP-2 water channel gene, we sought to isolate a GATA factor(s) expressed in collecting ducts and determined the role on the AQP-2 promoter. Two cDNAs encoding GATA factors were isolated from rat kidney, whose sequences were highly homologous with human GATA-2 and -3. Reverse-transcription PCR using dissected nephron segments revealed that rat GATA-3 but not GATA-2 was expressed in collecting ducts, thus indicating that GATA-3 could interact with GATA motifs in the AQP-2 promoter. Transactivation experiments utilizing the rat GATA-3 expression vector indicated that rat GATA-3 increased the AQP-2 promoter activity about fourfold. These results indicated that GATA motifs in the 5'-flanking region of the hAQP-2 gene were functional cis-elements and that GATA-3 in collecting ducts may be one of the important regulators of AQP-2 expression in vivo.

GATA-2 and GATA-3 regulate trophoblast-specific gene expression in vivo

We previously demonstrated that the zinc finger transcription factors GATA-2 and GATA-3 are expressed in trophoblast giant cells and that they regulate transcription from the mouse placental lactogen I gene promoter in a transfected trophoblast cell line. We present evidence here that both of these factors regulate transcription of the placental lactogen I gene, as well as the related proliferin gene, in trophoblast giant cells in vivo. Placentas lacking GATA-3 accumulate placental lactogen I and proliferin mRNAs to a level 50% below that reached in the wild-type placenta. Mutation of the GATA-2 gene had a similar effect on placental lactogen I expression, but led to a markedly greater reduction (5- to 6-fold) in proliferin gene expression. Placentas lacking GATA-2 secrete significantly less angiogenic activity than wild-type placentas as measured in an endothelial cell migration assay, consistent with a reduction in expression of the angiogenic hormone proliferin. Furthermore, within the same uterus the decidual tissue adjacent to mutant placentas displays markedly reduced neovascularization compared to the decidual tissue next to wild-type placentas. These results indicate that GATA-2 and GATA-3 are important in vivo regulators of trophoblast-specific gene expression and placental function, and reveal a difference in the effect of these two factors in regulating the synthesis of related placental hormones.

Negative regulation of the erythropoietin gene expression by the GATA transcription factors

We examined regulation of the human erythropoietin (Epo) gene through the GATA sequence in the Epo promoter and showed that Hep3B and HepG2 cells express human GATA-2 (hGATA-2) mRNA and protein. Nuclear extracts of QT6 cells transfected with hGATA-1, 2, or 3 transcription factors showed specific binding to the GATA element in the human Epo gene promoter by gel mobility shift assay. Transient transfection of Hep3B cells with hGATA-1, 2, or 3 showed that each of these transcription factors significantly decreased the level of expression of Epo mRNA as assessed by a competitive polymerase chain reaction. Transient transfection of Hep3B cells with hGATA-1, 2, and 3 and an Epo-reporter gene (growth hormone [GH]) construct showed significant inhibition of the Epo promoter. Antisense oligonucleotide for hGATA-2 transcription factor significantly increased the Epo protein in Hep3B cells under 1% O2 for 24 hours incubation. Furthermore, transient transfection of Hep3B cells with hGATA-1, 2, and 3 and an Epo-reporter gene (luciferase) construct also showed significant inhibition of the Epo promoter. However, transfection of the mutated GATA sequence of the Epo-luciferase gene with hGATA-1, 2, and 3 interfere with the inhibition of the Epo promoter. We conclude that the hGATA-1, 2, and 3 transcription factors specifically bind to the GATA element in the human Epo gene promoter and negatively regulate Epo gene expression.

Transcriptional activity of TAL1 in T cell acute lymphoblastic leukemia (T-ALL) requires RBTN1 or -2 and induces TALLA1, a highly specific tumor marker of T-ALL

TAL1, which is frequently activated in T cell acute lymphoblastic leukemia (T-ALL), encodes lineage-specific basic helix-loop-helix (bHLH) proteins that bind specifically to E-box DNA motif upon dimerization with ubiquitous basic helix-loop-helix proteins E47 or E12. RBTN1 and RBTN2, also frequently activated in T-ALL, encode proteins only with tandem cysteine-rich LIM domains. We found that aberrant expression of TAL1 detected in 11 out of 14 T-ALL cell lines was invariably accompanied by that of either RBTN1 or RBTN2. Forced expression of TAL1 together with RBTN1 or RBTN2, but not TAL1 alone, strongly induced artificial reporter genes in a TAL1/RBTN-negative T-ALL cell line, HPB-ALL. Such collaborative transcriptional activity of TAL1 and RBTN was not, however, observed in non-T cell lines, suggesting further involvement of some T cell-specific cofactors. In this context, we carried out preliminary evaluation of a potential role of the T cell-specific GATA-binding protein, GATA3, in the transcriptional activity of TAL1 and RBTN. We also showed that coexpression of TAL1 and RBTN1 in HPB-ALL strongly induced TALLA1, a highly specific T-ALL marker whose positivity correlated 100% with ectopic expression of TAL1 among various T-ALL cell lines. Collectively, ectopic TAL1 and RBTN1 or -2, together with some endogenous T cell-specific cofactors like GATA3, constitute a highly collaborative set of transcription factors whose aberrant activity in T cells may lead to leukemogenesis by modulating expression of downstream genes such as TALLA1.

[Genetic control of hematopoiesis]

Commitment and differentiation of hematopoietic stem cells are associated with the progressive restriction of cellular proliferation and the progressive expression of a subset of genes encoding the markers of mature cells. These two processes are genetically regulated and, in this paper, I review the expression and function of the GATA family of transcription factors as an example of this genetic regulation. GATA cis-acting elements are found in most of the regulatory regions of T-lymphoid, erythrocytic and megakaryocytic restricted genes. These GATA motifs are recognized by the members of a family of transcriptional regulators: the GATA family. Three members of this family, GATA-1, 2 and 3 are expressed in hematopoietic cells. They are necessary for the erythrocytic and megakaryocytic lineages (GATA-1), for the T-lymphoid lineage (GATA-3), and for the proliferation of uncommitted hematopoietic precursors (GATA-2). GATA-1 displays at least four functions: activation of the erythrocytic and megakaryocytic specific genes, regulation of the epsilon-->gamma globin switch and control of the cell cycle. These two last functions will be discussed to show the multiple facets of GATA-1 in the genetic regulation of hematopoiesis.

Transcription factor GATA-3 is required for development of the T-cell lineage

THE zinc-finger transcription factor GATA-3 is expressed in haematopoietic cells and in the developing kidney and nervous system. Within the haematopoietic lineages, expression of GATA-3 is restricted to thymocytes and T cells. Functionally important GATA-3 binding sites have been identified in multiple T-cell-specific genes. Mice containing homozygous null mutations of the GATA-3 gene die on embryonic day 12, precluding a detailed assessment of the role of GATA-3 in haematopoietic development. Here we have used murine embryonic stem (ES) cells containing homozygous mutations in the GATA-3 gene (GATA-3(-/-)) in conjunction with the RAG-2(-/-) (ref. 10) and C57BL/6 complementation systems to study the role of GATA-3 in mammalian haematopoiesis. Our results show that GATA-3(-/-) ES cells can contribute to the development of the mature erythroid, myelomonocytic and B-cell lineages, but fail to give rise to thymocytes or mature peripheral T cells. The differentiation of GATA-3(-/-) T cells is blocked at or before the earliest double-negative (CD4-/CD8-) stage of thymocyte development, such that the GATA-3(-/-) ES cells are unable to contribute measurably to the double-negative thymocyte population. These findings suggest that GATA-3 is an essential and specific regulator of early thymocyte development.

Involvement of transcription factors TCF-1 and GATA-3 in the initiation of the earliest step of T cell development in the thymus

Flow cytometric and immunocytochemical analyses of murine fetal thymus (FT) cells with antibodies to various surface markers and transcription factors reveal that the synthesis of TCF-1 and GATA-3 protein begins simultaneously in a fraction of the most immature population of FT cells, which have the phenotype of CD4-CD8-CD44+CD25-. No TCF-1-producing cells is found in the fetal liver (FL). In CD44+CD25- FT cells, the production of TCF-1 is immediately followed by intracellular expression of CD3 epsilon. It is also found that the T cell development from FL, but not FT, progenitors in the FT organ culture system is severely inhibited by the addition of antisense oligonucleotides for either TCF-1 or GATA-3. These results strongly suggest that TCF-1 and GATA-3 play essential roles in the initiation of the earliest steps of T cell development in the thymus.

Absence of T-cell- and B-cell-specific transcription factors TCF-1, GATA-3, and BSAP in Hodgkin's Reed-Sternberg cells

Based on the presence of T cell receptor-beta (TcR-beta) gene rearrangements in L428 and HDLM-1 cells, the expression of CD2 in HDLM-1 cells, and the presence of immunoglobulin heavy-chain (IgH) gene rearrangement in KM-H2 cells, some researchers have concluded that these long-term cell lines derived from patients with Hodgkin's disease are lymphoid in nature. The information obtained from these cell lines has also been used in arguments for a lymphoid origin of H-RS cells in tissue despite the frequent absence of lymphoid markers and Ig/TcR gene rearrangements in these cells. We questioned whether one can use the limited expression of lymphoid markers or the limited gene rearrangement to conclude that H-RS cells have a lymphoid origin, because these markers may be aberrant in tumor cells. In this study, we examined the expression of two T-cell-specific transcription factors (TCF-1 and GATA-3) and one B-cell-specific transcription factor (BSAP) in cultured H-RS cells by using a gel mobility shift assay. The sensitivity and specificity of this assay for determination of cell lineage have been established in a large number of cultured human and murine cell lines. All three types of H-RS cell lines were consistently negative for BSAP, TCF-1, and GATA-3. The absence of GATA-3 was confirmed in H-RS cells in tissues by an in situ hybridization technique. Virtually all B-cell lines, with the exception of some myeloma cell lines, are positive for BSAP, which is the transcription factor for promoters for several B-cell markers, including VpreB1, lambda 5, CD19, and CD20. All T-cell lines tested were positive for TCF-1 and GATA-3, which are the transcription factors for promoters for several T-cell-restricted markers, including CD2, CD3, TcR, and lck. The absence of BSAP, TCF-1, and GATA-3 clearly indicates an underlying difference between H-RS cells and lymphoid cells.

GATA transcription factors associate with a novel class of nuclear bodies in erythroblasts and megakaryocytes

The nuclear distribution of GATA transcription factors in murine haemopoietic cells was examined by indirect immunofluorescence. Specific bright foci of GATA-1 fluorescence were observed in erythroleukaemia cells and primary murine erythroblasts and megakaryocytes, in addition to diffuse nucleoplasmic localization. These foci, which were preferentially found adjacent to nucleoli or at the nuclear periphery, did not represent sites of active transcription or binding of GATA-1 to consensus sites in the beta-globin loci. Immunoelectron microscopy demonstrated the presence of intensely labelled structures likely to represent the GATA-1 foci seen by immunofluorescence. The GATA-1 nuclear bodies differed from previously described nuclear structures and there was no co-localization with nuclear antigens involved in RNA processing or other ubiquitous (Spl, c-Jun and TBP) or haemopoietic (NF-E2) transcription factors. Interestingly, GATA-2 and GATA-3 proteins also localized to the same nuclear bodies in cell lines co-expressing GATA-1 and -2 or GATA-1 and -3 gene products. This pattern of distribution is, thus far, unique to the GATA transcription factors and suggests a protein-protein interaction with other components of the nuclear bodies via the GATA zinc finger domain.

Activation of the interleukin-5 promoter by cAMP in murine EL-4 cells requires the GATA-3 and CLE0 elements

Interleukin-5 (IL-5) plays a central role in the growth and differentiation of eosinophils and contributes to several disease states including asthma. Accumulating evidence suggests a role for cAMP as an immunomodulator; agents that increase intracellular cAMP levels have been shown to inhibit production of cytokines predominantly produced by T helper (Th) 1 cells such as IL-2 and interferon gamma (IFN-gamma). In contrast, the production of IL-5, predominantly produced by Th2 cells, is actually enhanced by these agents. In this report, we have performed transient transfection experiments with IL-5 promoter-reporter gene constructs, DNase I footprinting assays, and electrophoretic mobility shift assays to investigate the key regulatory regions necessary for activation of the IL-5 promoter by dibutyryl cAMP and phorbol esters in the mouse thymoma line EL-4. Taken together, our data demonstrate the critical importance of two sequences within the IL-5 5'-flanking region for activation by these agents in EL-4 cells: one, a highly conserved 15-base pair element present in genes expressed by Th2 cells, called the conserved lymphokine element 0 (CLE0; located between -53 and -39 in the IL-5 promoter), and the other, two overlapping binding sites for the transcription factor GATA-3 (but not GATA-4) between -70 and -59. Taken together, our data suggest that activation via the unique sequence combination GATA/CLE0 results in selective expression of the IL-5 gene in response to elevated levels of intracellular cAMP.

Sequence of the 5' regulatory domain of the gene encoding the rat beta 2-adrenergic receptor

Restriction mapping and sequence analysis of the gene encoding the rat beta 2 adrenergic receptor (beta 2AR) revealed an error affecting most of the 5'-flanking domain, located between -192 and -2245 bp in the only published sequence of this gene [Buckland et al., Nucleic Acids Res. 18 (1990) 682]. The correct sequence lacks a TATA box, contains 67% G + C residues in the first 500 nucleotides upstream from the start codon, and contains putative glucocorticoid, thyroid hormone and cAMP-response elements.

Identification and cloning of the G3B cDNA encoding a 3' segment of a protein binding to GATA-3

The transcription factor GATA-3 contributes to the expression of several genes critical for T-cell function and development, including the T-cell receptor alpha and beta chains. We report here the isolation of a human cDNA clone which encodes a 3' segment of a novel protein with three zinc fingers. This protein, which we termed G3B, can interact with GATA-3 in vitro. Its mRNA is expressed in T and B cells. Thus, G3B may represent a potential regulator of GATA-3 function.

Targeted disruption of the GATA3 gene causes severe abnormalities in the nervous system and in fetal liver haematopoiesis

GATA-3 is one member of a growing family of related transcription factors which share a strongly conserved expression pattern in all vertebrate organisms. In order to elucidate GATA-3 function using a direct genetic approach, we have disrupted the murine gene by homologous recombination in embryonic stem cells. Mice heterozygous for the GATA3 mutation are fertile and appear in all respects to be normal, whereas homozygous mutant embryos die between days 11 and 12 postcoitum (p.c.) and display massive internal bleeding, marked growth retardation, severe deformities of the brain and spinal cord, and gross aberrations in fetal liver haematopoiesis.