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

Expression of the transcription factor GATA3 in the postnatal mouse central nervous system

GATA binding protein 3 (GATA3) is an important regulator of central nervous system (CNS) development, but its expression pattern in the postnatal CNS has not been studied. In the present study, we examined the distribution of GATA3 mRNA in the mouse CNS at different postnatal stages by in situ hybridization. During the first 2 weeks of postnatal development, numerous GATA3-expressing cells were found in the intergeniculate leaf, ventral lateral geniculate nucleus, pretectal nucleus, nucleus of the posterior commissure, superior colliculus, inferior colliculus, periaqueductal grey, substantia nigra and raphe nuclei. Few notable changes in the profile of GATA3 expression occurred over this time period. As postnatal development progressed, however, GATA3 expression weakened, and was maintained in only a few regions of the adult CNS. Throughout the brain, we found that GATA3-expressing cells were NeuN-positive, and no colocalization with glial fibrillary acidic protein (GFAP) was observed. In the substantia nigra, GATA3 was exclusively expressed in cells of the reticulate part and some of which were found to be GABAergic. This study presents a comprehensive overview of GATA3 expression in the CNS throughout postnatal life, and the dynamics that we observed provide insights for further investigations of the roles of GATA3 in postnatal development and the maintenance of the mature CNS.

The Wilms' tumor suppressor Wt1 activates transcription of the erythropoietin receptor in hematopoietic progenitor cells

The Wilms' tumor protein Wt1 is required for embryonic development and has been implicated in hematologic disorders. Since Wt1 deficiency may compromise the proliferation and differentiation of erythroid progenitor cells, we analyzed the possible role of the transcriptionally active Wt1 isoform, Wt1(-KTS), in regulating the expression of the erythropoietin receptor (EpoR). Wt1 and EpoR were coexpressed in CD117(+) hematopoietic progenitor cells and in several hematopoietic cell lines. CD117(+) cells of Wt1-deficient murine embryos (Wt1(-/-)) exhibited a significantly lower proliferation response to recombinant erythropoietin than CD117(+) cells of heterozygous (Wt1(+/-)) and wild-type littermates (Wt1(+/+)). EpoR expression was significantly diminished in hematopoietic progenitors (CD117(+)) that lacked Wt1, and the erythroid colony-forming capacity was reduced by more than 50% in fetal liver cells of Wt1-deficient embryonic mice. Wt1(-KTS) significantly increased endogenous EpoR transcripts in transfected cells. The proximal EpoR promoter of human and mouse was stimulated more than 10-fold by Wt1(-KTS) in transiently cotransfeced K562 erythroleukemia cells. A responsible cis-element, which is highly conserved in the EpoR promoter of human and mouse, was identified by mutation analysis, electrophoretic mobility shift assay, and chromatin immunoprecipitation assay. In conclusion, activation of the EpoR gene by Wt1 may represent an important mechanism in normal hematopoiesis.

GATA1-related leukaemias

GATA1 is a prototypical lineage-restricted transcription factor that is central to the correct differentiation, proliferation and apoptosis of erythroid and megakaryocytic cells. Mutations in GATA1 can generate a truncated protein, which contributes to the genesis of transient myeloproliferative disorder (TMD) and acute megakaryoblastic leukaemia (AMKL) in infants with Down syndrome. Similarly, Gata1 knockdown to 5% of its wild-type level causes high incidence of erythroid leukaemia in mice. The GATA1-related leukaemias in both human and mouse could provide important insights into the mechanism of multi-step leukaemogenesis. Efforts are afoot to produce mouse models that are reflective of TMD and AMKL.

Transcription factor GATA-3 regulates the transcriptional activity of dopamine beta-hydroxylase by interacting with Sp1 and AP4

GATA-3 is a zinc finger transcription factor that is expressed in T cell lineages as well as in the nervous system during development. In this study, we report that forced expression of GATA-3 resulted in an increased number of dopamine beta-hydroxylase (DBH)-expressing neurons in primary neural crest stem cell (NCSC) culture, suggesting that the DBH gene may be a downstream target gene of GATA-3. GATA-3 robustly transactivates the promoter function of the noradrenaline (NA)-synthesizing DBH gene, via two specific upstream promoter domains; one at -62 to -32 bp and the other at -891 to -853 bp. Surprisingly, none of these domains contain GATA-3 binding sites but encompass binding motifs for transcription factors Sp1 and AP4, respectively. Protein-protein interaction analyses both in vitro and in vivo and chromatin immunoprecipitation (ChIP) assays showed that GATA-3 effects its transcriptional regulatory function through physical interactions with these transcription factors.

GATA3 mRNA in ginbuna crucian carp (Carassius auratus langsdorfii): cDNA cloning, splice variants and expression analysis

GATA3, a transcriptional activator, plays a critical role in the development of T-cells and differentiation to T helper type 2 cells. To date, no information is available on the role of GATA3 in the teleost immune system. We identified full-length cDNA and alternatively spliced variants of ginbuna crucian carp GATA3 (gbGATA3). The gbGATA3 gene is transcribed into multiple splice variants lacking either one or both zinc finger domains, although the sequences of both domains are fully conserved between ginbuna and other vertebrates. We found that alternative splice site and stop codon in gbGATA3 intron 3, located between exons that separately encode the two zinc finger domains, are conserved among teleosts, suggesting that teleost GATA3 gene can be translated into multiple isoforms. RT-PCR analysis revealed that the gbGATA3 is strongly expressed in the brain, thymus and gill of unstimulated fish. Moreover, gbGATA3 expression was detected in surface-IgM-negative lymphocytes among kidney cells sorted by FACS. Real-time PCR demonstrated that expression levels of full-length gbGATA3 and the splice variants differed with tissue type, but full length was always the predominantly expressed form. These results suggest that gbGATA3, including its splice variants, is involved in teleost T-cell function.

Role of the GATA family of transcription factors in endocrine development, function, and disease

The WGATAR motif is a common nucleotide sequence found in the transcriptional regulatory regions of numerous genes. In vertebrates, these motifs are bound by one of six factors (GATA1 to GATA6) that constitute the GATA family of transcriptional regulatory proteins. Although originally considered for their roles in hematopoietic cells and the heart, GATA factors are now known to be expressed in a wide variety of tissues where they act as critical regulators of cell-specific gene expression. This includes multiple endocrine organs such as the pituitary, pancreas, adrenals, and especially the gonads. Insights into the functional roles played by GATA factors in adult organ systems have been hampered by the early embryonic lethality associated with the different Gata-null mice. This is now being overcome with the generation of tissue-specific knockout models and other knockdown strategies. These approaches, together with the increasing number of human GATA-related pathologies have greatly broadened the scope of GATA-dependent genes and, importantly, have shown that GATA action is not necessarily limited to early development. This has been particularly evident in endocrine organs where GATA factors appear to contribute to the transcription of multiple hormone-encoding genes. This review provides an overview of the GATA family of transcription factors as they relate to endocrine function and disease.

GATA factors induce mouse embryonic stem cell differentiation toward extraembryonic endoderm

The GATA family of transcription factors are implicated in early embryonic development. There are six factors in this family in vertebrates. GATA4 and GATA6 have been demonstrated to induce mouse embryonic stem (mES) cells differentiation toward extraembryonic endoderm (ExE). We investigated the effect of GATA3 on the differentiation of mES cells both in the ES cell and in the embryoid body (EB) states. The results demonstrate that GATA3 overexpression can initiate the ES cell differentiation program toward ExE. Furthermore, overexpression of GATA1 and GATA2 in ES cells and EBs resulted in similar effects. We believe this finding can augment our understanding of mouse ES cell differentiation.

Detailed molecular characterization of cord blood-derived endothelial progenitors

OBJECTIVE

Given their involvement in pathological and physiological angiogenesis, there has been growing interest in understanding and manipulating endothelial progenitor cells (EPC) for therapeutic purposes. However, detailed molecular analysis of EPC before and during endothelial differentiation is lacking and is the subject of the present study.

MATERIALS AND METHODS

We report a detailed microarray gene-expression profile of freshly isolated (day 0) human cord blood (CB)-derived EPC (CD133+KDR+ or CD34+KDR+), and at different time points during in vitro differentiation (early: day 13; late: day 27).

RESULTS

Data obtained reflect an EPC transcriptome enriched in genes related to stem/progenitor cells properties (chromatin remodeling, self-renewal, signaling, cytoskeleton organization and biogenesis, recruitment, and adhesion). Using a complementary DNA microarray enriched in intronic transcribed sequences, we observed, as well, that naturally transcribed intronic noncoding RNAs were specifically expressed at the EPC stage.

CONCLUSION

Taken together, we have defined the global gene-expression profile of CB-derived EPC during the process of endothelial differentiation, which can be used to identify genes involved in different vascular pathologies.

Expression of GATA-3 in epidermis and hair follicle: Relationship to p63

The epidermis is a multi-layered stratified epithelium continuously renewed by differentiating keratinocytes that develops by the action of p63, a member of the p53 family. The TP63 contains two promoters, resulting in the expression of different proteins, containing (TAp63) or not (DeltaNp63) an amino-terminal transactivation domain, which contribution in skin formation is not fully understood. We found that p63 binds and transactivate GATA-3 promoter, which in turn transactivate IKKalpha, two pivotal regulators of epithelial development. Indeed, GATA-3 is a regulator of cell lineage in skin and hair follicles formation. To further study the relationship between GATA-3 and p63 isoforms here we investigated their expression during keratinocyte differentiation, in human epidermis and hair follicle.

Calcineurin in reactive astrocytes plays a key role in the interplay between proinflammatory and anti-inflammatory signals

Maladaptive inflammation is a major suspect in progressive neurodegeneration, but the underlying mechanisms are difficult to envisage in part because reactive glial cells at lesion sites secrete both proinflammatory and anti-inflammatory mediators. We now report that astrocytes modulate neuronal resilience to inflammatory insults through the phosphatase calcineurin. In quiescent astrocytes, inflammatory mediators such as tumor necrosis factor-alpha (TNF-alpha) recruits calcineurin to stimulate a canonical inflammatory pathway involving the transcription factors nuclear factor kappaB (NFkappaB) and nuclear factor of activated T-cells (NFAT). However, in reactive astrocytes, local anti-inflammatory mediators such as insulin-like growth factor I also recruit calcineurin but, in this case, to inhibit NFkappaB/NFAT. Proof of concept experiments in vitro showed that expression of constitutively active calcineurin in astrocytes abrogated the inflammatory response after TNF-alpha or endotoxins and markedly enhanced neuronal survival. Furthermore, regulated expression of constitutively active calcineurin in astrocytes markedly reduced inflammatory injury in transgenic mice, in a calcineurin-dependent manner. These results suggest that calcineurin forms part of a molecular pathway whereby reactive astrocytes determine the outcome of the neuroinflammatory process by directing it toward either its resolution or its progression.

Cell lineage regulators in B and T cell development

This special issue highlights a pivotal set of regulatory molecules that have emerged as central controllers of cell-type identity in the immune system. Each in its own way has been considered as a kind of 'master' regulator of a particular cell fate choice, but the actual modes of action of these factors vary widely. The comparison among them sheds light on the different ways that an essential regulatory input can affect cellular identity.

Positive Cross-Regulatory Loop Ties GATA-3 to Estrogen Receptor α Expression in Breast Cancer

The transcription factor GATA-3 is required for normal mammary gland development, and its expression is highly correlated with estrogen receptor alpha (ER alpha) in human breast tumors. However, the functional role of GATA-3 in ER alpha-positive breast cancers is yet to be established. Here, we show that GATA-3 is required for estradiol stimulation of cell cycle progression in breast cancer cells. The role of GATA-3 in estradiol signaling requires the direct positive regulation of the expression of the ER alpha gene itself by GATA-3. GATA-3 binds to two cis-regulatory elements located within the ER alpha gene, and this is required for RNA polymerase II recruitment to ER alpha promoters. Reciprocally, ER alpha directly stimulates the transcription of the GATA-3 gene, indicating that these two factors are involved in a positive cross-regulatory loop. Moreover, GATA-3 and ER alpha regulate their own expression in breast cancer cells. Hence, this transcriptional coregulatory mechanism accounts for the robust coexpression of GATA-3 and ER alpha in human breast cancers. In addition, these results highlight the crucial role of GATA-3 for the response of ER alpha-positive breast cancers to estradiol. Moreover, they identify GATA-3 as a critical component of the master cell-type-specific transcriptional network including ER alpha and FoxA1 that dictates the phenotype of hormone-dependent breast cancer.

GATA3 controls the expression of CD5 and the T cell receptor during CD4 T cell lineage development

The transcription factor GATA3 is essential at multiple stages of T cell development, including the earliest double-negative stages, beta-selection and CD4 single-positive thymocytes. Here, we show that in CD2-GATA3 transgenic mice, with enforced GATA3 expression driven by the CD2 promoter, thymocytes have reduced levels of CD5, which is a negative regulator of TCR signaling participating in TCR repertoire fine-tuning. Reduction of CD5 expression was most prominent in CD4(+)CD8(+) double-positive (DP) cells and was associated with increased levels of the transcription factor E2A. Conversely, GATA3-deficient DP thymocytes showed consistently higher CD5 levels and defective TCR up-regulation during their development towards the CD4(lo)CD8(lo) subpopulation. CD2-GATA3 transgenic mice carrying the MHC class II-restricted TCR DO11.10 also manifested decreased CD5 levels. As in these TCR-transgenic mice reduced CD5 expression cannot result from an effect of GATA3 on repertoire selection, we conclude that enforced GATA3 interferes with the developmentally regulated increase of CD5 levels. Enforced GATA3 expression in DO11.10 transgenic mice was also accompanied by enhanced TCR expression during CD4 positive selection. Because GATA3 is induced by TCR signaling in DP thymocytes, our findings indicate that GATA3 establishes a positive feedback loop that increases TCR surface expression in developing CD4 lineage cells.

Role of erythropoietin in the brain

Multi-tissue erythropoietin receptor (EPO-R) expression provides for erythropoietin (EPO) activity beyond its known regulation of red blood cell production. This review highlights the role of EPO and EPO-R in brain development and neuroprotection. EPO-R brain expression includes neural progenitor cells (NPC), neurons, glial cells and endothelial cells. EPO is produced in brain in a hypoxia sensitive manner, stimulates NPC proliferation and differentiation, and neuron survival, and contributes to ischemic preconditioning. Mice lacking EPO or EPO-R exhibit increased neural cell apoptosis during development before embryonic death due to severe anemia. EPO administration provides neural protection in animal models of brain ischemia and trauma, reducing the extent of injury and damage. Intrinsic EPO production in brain and EPO stimulation of endothelial cells contribute to neuroprotection and these are of particular importance since only low levels of EPO appear to cross the blood-brain barrier when administered at high dose intravenously. The therapeutic potential of EPO for brain ischemia/trauma and neurodegenerative diseases has shown promise in early clinical trial and awaits further validation.

Constitutive activation of Flt3 and STAT5A enhances self-renewal and alters differentiation of hematopoietic stem cells

OBJECTIVE

To model human leukemogenesis by transduction of human hematopoietic stem cells (HSC) with genes associated with leukemia and expressed in leukemic stem cells.

METHODS

Constitutive activation of Flt3 (Flt3-ITD) has been reported in 25 to 30% of patients with acute myeloid leukemia (AML). Retroviral vectors expressing constitutively activated Flt3 and STAT5A were used to transduce human cord blood CD34(+) cells and HSC cell self-renewal and differentiation were evaluated.

RESULTS

We have demonstrated that retroviral transduction of Flt3 mutations into CD34(+) cells enhanced HSC self-renewal as measured in vitro in competitive stromal coculture and limiting-dilution week-2 cobblestone (CAFC) assays. Enhanced erythropoiesis and decreased myelopoiesis were noted together with strong activation of STAT5A. Consequently, transduction studies were undertaken with a constitutively active mutant of STAT5A (STAT5A[1( *)6]) and here also a marked, selective expansion of transduced CD34(+) cells was noted, with a massive increase in self-renewing CAFC detectable at both 2 and 5 weeks of stromal coculture. Differentiation was biased to erythropoiesis, including erythropoietin independence, with myeloid maturation inhibition. The observed phenotypic changes correlated with differential gene expression, with a number of genes differentially regulated by both the Flt3 and STAT5A mutants. These included upregulation of genes involved in erythropoiesis and downregulation of genes involved in myelopoiesis. The phenotype of week-2 self-renewing CAFC also characterized primary Flt3-ITD(+) AML bone marrow samples. Isolation of leukemic stem cells (LSC) with a CD34(+), CD38(-), HLA-DR(-) phenotype was undertaken with Flt3-ITD(+) AML samples resulting in co-purification of early CAFC. Gene expression of LSC relative to the bulk leukemic population revealed upregulation of homeobox genes (HOXA9, HOXA5) implicated in leukemogenesis, and hepatic leukemia factor (HLF) involved in stem cell proliferation.

CONCLUSION

Myeloid leukemogenesis is a multi-stage process that can involve constitutively activated receptors and downstream pathways involving STAT5, HOX genes, and HLF.

A Gata2 intronic enhancer confers its pan-endothelia-specific regulation

GATA-2, a transcription factor that has been shown to play important roles in multiple organ systems during embryogenesis, has been ascribed the property of regulating the expression of numerous endothelium-specific genes. However, the transcriptional regulatory hierarchy governing Gata2 activation in endothelial cells has not been fully explored. Here, we document GATA-2 endothelial expression during embryogenesis by following GFP expression in Gata2-GFP knock-in embryos. Using founder transgenic analyses, we identified a Gata2 endothelium enhancer in the fourth intron and found that Gata2 regulation by this enhancer is restricted to the endocardial, lymphatic and vascular endothelium. Whereas disruption of three ETS-binding motifs within the enhancer diminished its activity, the ablation of its single E box extinguished endothelial enhancer-directed expression in transgenic mice. Development of the endothelium is known to require SCL (TAL1), and an SCL-E12 (SCL-Tcfe2a) heterodimer can bind the crucial E box in the enhancer in vitro. Thus, GATA-2 is expressed early in lymphatic, cardiac and blood vascular endothelial cells, and the pan-endothelium-specific expression of Gata2 is controlled by a discrete intronic enhancer.

Dynamic regulation of Gata factor levels is more important than their identity

Three Gata transcription factors (Gata1, -2, and -3) are essential for hematopoiesis. These factors are thought to play distinct roles because they do not functionally replace each other. For instance, Gata2 messenger RNA (mRNA) expression is highly elevated in Gata1-null erythroid cells, yet this does not rescue the defect. Here, we test whether Gata2 and -3 transgenes rescue the erythroid defect of Gata1-null mice, if expressed in the appropriate spatiotemporal pattern. Gata1, -2, and -3 transgenes driven by beta-globin regulatory elements, directing expression to late stages of differentiation, fail to rescue erythropoiesis in Gata1-null mutants. In contrast, when controlled by Gata1 regulatory elements, directing expression to the early stages of differentiation, Gata1, -2, and -3 do rescue the Gata1-null phenotype. The dramatic increase of endogenous Gata2 mRNA in Gata1-null progenitors is not reflected in Gata2 protein levels, invoking translational regulation. Our data show that the dynamic spatiotemporal regulation of Gata factor levels is more important than their identity and provide a paradigm for developmental control mechanisms that are hard-wired in cis-regulatory elements.

Lipid defect underlies selective skin barrier impairment of an epidermal-specific deletion of Gata-3

Skin lies at the interface between the complex physiology of the body and the external environment. This essential epidermal barrier, composed of cornified proteins encased in lipids, prevents both water loss and entry of infectious or toxic substances. We uncover that the transcription factor GATA-3 is required to establish the epidermal barrier and survive in the ex utero environment. Analysis of Gata-3 mutant transcriptional profiles at three critical developmental stages identifies a specific defect in lipid biosynthesis and a delay in differentiation. Genomic analysis identifies highly conserved GATA-3 binding sites bound in vivo by GATA-3 in the first intron of the lipid acyltransferase gene AGPAT5. Skin from both Gata-3-/- and previously characterized barrier-deficient Kruppel-like factor 4-/- newborns up-regulate antimicrobial peptides, effectors of innate immunity. Comparison of these animal models illustrates how impairment of the skin barrier by two genetically distinct mechanisms leads to innate immune responses, as observed in the common human skin disorders psoriasis and atopic dermatitis.

GATA-3 maintains the differentiation of the luminal cell fate in the mammary gland

The GATA family of transcription factors plays fundamental roles in cell-fate specification. However, it is unclear if these genes are necessary for the maintenance of cellular differentiation after development. We identified GATA-3 as the most highly enriched transcription factor in the mammary epithelium of pubertal mice. GATA-3 was found in the luminal cells of mammary ducts and the body cells of terminal end buds (TEBs). Upon conditional deletion of GATA-3, mice exhibited severe defects in mammary development due to failure in TEB formation during puberty. After acute GATA-3 loss, adult mice exhibited undifferentiated luminal cell expansion with basement-membrane detachment, which led to caspase-mediated cell death in the long term. Further, FOXA1 was identified as a downstream target of GATA-3 in the mammary gland. This suggests that GATA-3 actively maintains luminal epithelial differentiation in the adult mammary gland, which raises important implications for the pathogenesis of breast cancer.

Gata-3 is an essential regulator of mammary-gland morphogenesis and luminal-cell differentiation

The transcription factor Gata-3 is a defining marker of the 'luminal' subtypes of breast cancer. To gain insight into the role of Gata-3 in breast epithelial development and oncogenesis, we have explored its normal function within the mammary gland by conditionally deleting Gata-3 at different stages of development. We report that Gata-3 has essential roles in the morphogenesis of the mammary gland in both the embryo and adult. Through the discovery of a novel marker (beta3-integrin) of luminal progenitor cells and their purification, we demonstrate that Gata-3 deficiency leads to an expansion of luminal progenitors and a concomitant block in differentiation. Remarkably, introduction of Gata-3 into a stem cell-enriched population induced maturation along the alveolar luminal lineage. These studies provide evidence for the existence of an epithelial hierarchy within the mammary gland and establish Gata-3 as a critical regulator of luminal differentiation.

Transcriptome and phenotypic analysis reveals Gata3-dependent signalling pathways in murine hair follicles

The transcription factor Gata3 is crucially involved in epidermis and hair follicle differentiation. Yet, little is known about how Gata3 co-ordinates stem cell lineage determination in skin, what pathways are involved and how Gata3 differentially regulates distinct cell populations within the hair follicle. Here, we describe a conditional Gata3-/- mouse (K14-Gata3-/-) in which Gata3 is specifically deleted in epidermis and hair follicles. K14-Gata3-/- mice show aberrant postnatal growth and development, delayed hair growth and maintenance, abnormal hair follicle organization and irregular pigmentation. After the first hair cycle, the germinative layer surrounding the dermal papilla was not restored; instead, proliferation was pronounced in basal epidermal cells. Transcriptome analysis of laser-dissected K14-Gata3-/- hair follicles revealed mitosis, epithelial differentiation and the Notch, Wnt and BMP signaling pathways to be significantly overrepresented. Elucidation of these pathways at the RNA and protein levels and physiologic endpoints suggests that Gata3 integrates diverse signaling networks to regulate the balance between hair follicle and epidermal cell fates.

Parathyroid Development and the Role of Tubulin Chaperone E

The development of the parathyroid glands involves complex embryonic processes of cell-specific differentiation and migration of the glands from their sites of origin in the pharynx and pharyngeal pouches to their final positions along the ventral midline of the pharyngeal and upper thoracic region. The recognition of several distinct genetic forms of isolated and syndromic hypoparathyroidism led us to review the recent findings on the molecular mechanisms of the development of the parathyroid glands. Although far from being understood, a special emphasis was given to the possible role of tubulin chaperone E (TBCE), which was implicated in the pathogenesis of the hypopathyroidism, retardation and dysmorphism (HRD) syndrome. The novel finding that TBCE plays a critical role in the formation of the parathyroid opens a novel domain of research, not anticipated previously, into the complex process of parathyroid development.

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.

GATA-3 regulates the transcriptional activity of tyrosine hydroxylase by interacting with CREB

The zinc finger transcription factor GATA-3 is a master regulator of type 2 T-helper cell development. Interestingly, in GATA-3-/- mice, noradrenaline (NA) deficiency is a proximal cause of embryonic lethality. However, neither the role of GATA-3 nor its target gene(s) in the nervous system were known. Here, we report that forced expression of GATA-3 resulted in an increased number of tyrosine hydroxylase (TH) expressing neurons in primary neural crest stem cell (NCSC) culture. We also found that GATA-3 transactivates the promoter function of TH via specific upstream sequences, a domain of the TH promoter residing at -61 to -39 bp. Surprisingly, this domain does not contain GATA-3 binding sites but possesses a binding motif, a cAMP response element (CRE), for the transcription factor, CREB. In addition, we found that site-directed mutation of this CRE almost completely abolished transactivation of the TH promoter by GATA-3. Furthermore, protein-protein interaction assays showed that GATA-3 is able to physically interact with CREB in vitro as well as in vivo. Based on these results, we propose that GATA-3 may regulate TH gene transcription via a novel and distinct protein-protein interaction, and directly contributes to NA phenotype specification.

Proliferin enhances microvilli formation and cell growth of neuroblastoma cells

Proliferins (also termed mitogen-regulated proteins; MRP/PLFs) belong to the prolactin gene family. Mrp/Plfs are involved in angiogenesis of the uterus and placenta and maximally expressed during midgestation and decline through the remainder of the gestation period in mouse placenta. The tissue expressions of Mrp/Plfs are mainly documented in placenta, hair follicles of skin and in wound healing. In this report, we demonstrate that Plf1, Plf1 minus exon3, Plf2 and Mrp3 but not Mrp4 are expressed in mouse whole brain by diagnostic RT-PCR and Western blotting. The expression levels of Mrp/Plf mRNAs in mouse brains were low during the neonatal period, but higher in embryonic and adult stages, indicating Mrp/Plfs expression profiles are different in mouse brain and placenta. Interestingly, endogenous Mrp/Plfs were detected using immunostaining both in mouse brain sections and the neuroblastoma cell line, Neuro-2a cells. The function of PLF1 was explored by expressing exogenous PLF1 in Neuro-2a cells. This resulted in increased microvilli. Neuro-2a cells with stable expression of PLF1 had increased proliferation compared with normal and stable expressing EGFP cells when cell reached saturation density. Together these data, strongly suggest that MRP/PLFs mediate microvilli formation and contribute to cell proliferation of neuroblastoma cells.

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.

The essential haematopoietic transcription factor Scl is also critical for neuronal development

Abstract The basic helix-loop-helix (bHLH) transcription factor Scl displays tissue-restricted expression and is critical for the establishment of the haematopoietic system; loss of Scl results in embryonic death due to absolute anaemia. Scl is also expressed in neurons of the mouse diencephalon, mesencephalon and metencephalon; however, its requirement in those sites remains to be determined. Here we report conditional deletion of Scl in neuronal precursor cells using the Cre/LoxP system. Neuronal-Scl deleted mice died prematurely, were growth retarded and exhibited an altered motor phenotype characterized by hyperactivity and circling. Moreover, ablation of Scl in the nervous system affected brain morphology with abnormal neuronal development in brain regions known to express Scl under normal circumstances; there was an almost complete absence of Scl-null neurons in the hindbrain and partial loss of Scl-null neurons in the thalamus and midbrain from early neurogenesis onwards. Our results demonstrate a crucial role for Scl in the development of Scl-expressing neurons, including gamma-aminobutyric acid (GABA)ergic interneurons. Our study represents one of the first demonstrations of functional overlap of a single bHLH protein that regulates neural and haematopoietic cell development. This finding underlines Scl's critical function in cell fate determination of mesodermal as well as neuroectodermal tissues.

The embryonic aorta-gonad-mesonephros region as a generator of haematopoietic stem cells

During mammalian embryonic development the definitive haematopoietic stem cells (HSCs) may arise either in the extra-embryonic mesoderm or in the aorta-gonad-mesonephros (AGM) region that forms in close proximity to the assembling urogenital system, generating the gonad, cortex of the adrenal gland and metanephros. Researchers have been attempting for a long time to define the region of importance for generating the definitive HSCs that colonize the fetal liver and bone marrow, the two major sites where haematopoiesis takes place in the adult. The fetal liver might gain HSCs from both of the primary haematopoietic sources, but the extra-embryonic HSCs seem not to be able to colonize adult bone marrow directly. It is known that the microenvironment around the HSCs is important for directing cell fates, but we do not yet have much idea about the cell-cell interactions, tissue interactions and molecules that regulate cell behaviour in the AGM. We will here discuss the contribution of the AGM to definitive haematopoiesis in mammals and review some of the cell-cell interactions and associated signalling systems involved in the development of AGM stem cells.

Specification of Drosophila aCC motoneuron identity by a genetic cascade involving even-skipped, grain and zfh1

During nervous system development, combinatorial codes of regulators act to specify different neuronal subclasses. However, within any given subclass, there exists a further refinement, apparent in Drosophila and C. elegans at single-cell resolution. The mechanisms that act to specify final and unique neuronal cell fates are still unclear. In the Drosophila embryo, one well-studied motoneuron subclass, the intersegmental motor nerve (ISN), consists of seven unique motoneurons. Specification of the ISN subclass is dependent upon both even-skipped (eve) and the zfh1 zinc-finger homeobox gene. We find that ISN motoneurons also express the GATA transcription factor Grain, and grn mutants display motor axon pathfinding defects. Although these three regulators are expressed by all ISN motoneurons, these genes act in an eve-->grn-->zfh1 genetic cascade unique to one of the ISN motoneurons, the aCC. Our results demonstrate that the specification of a unique neuron, within a given subclass, can be governed by a unique regulatory cascade of subclass determinants.

GATA-3 promotes Th2 responses through three different mechanisms: induction of Th2 cytokine production, selective growth of Th2 cells and inhibition of Th1 cell-specific factors

Naïve CD4 T cells can differentiate into at least two different types of T helpers, Th1 and Th2 cells. Th2 cells, capable of producing IL-4, IL-5 and IL-13, are involved in humoral immunity against extracellular pathogens and in the induction of asthma and other allergic diseases. In this review, we summarize recent reports regarding the transcription factors involved in Th2 differentiation and cell expansion, including Stat5, Gfi-1 and GATA-3. Stat5 activation is necessary and sufficient for IL-2-mediated function in Th2 differentiation. Enhanced Stat5 signaling induces Th2 differentiation independent of IL-4 signaling; although it does not up-regulate GATA-3 expression, it does require the presence of GATA-3 for its action. Gfi-1, induced by IL-4, promotes the expansion of GATA-3-expressing cells. Analysis of conditional Gata3 knockout mice confirmed the critical role of GATA-3 in Th2 cell differentiation (both IL-4 dependent and IL-4 independent) and in Th2 cell proliferation and also showed the importance of basal GATA-3 expression in inhibiting Th1 differentiation.

A novel mutation in the GATA3 gene in a family with HDR syndrome (Hypoparathyroidism, sensorineural Deafness and Renal anomaly syndrome)

We report here on a girl and her father with HDR syndrome (Hypoparathyroidism, sensorineural Deafness and Renal anomaly syndrome). The proband, an 11 year-old girl, complained of periodic tetany lasting for 6 years, and also used a hearing aid because of sensorineural hearing impairment. Furthermore, she had hemimegalencephaly, and had been taking an anti-epileptic agent to treat psychomotor seizures for 6 years. Endocrine assessment showed modest hypocalcemia, hyperphosphatemia and hypophosphaturia with lower normal parathyroid hormone concentration, and she had no renal abnormalities. Her father, who was 40 years old at the time of the investigation, had sensorineural hearing impairment, a lower than normal calcium level and normal renal function. Direct sequencing after PCR amplification of genomic DNA revealed a novel insertional mutation (405insC) in the GATA3 gene of both patients. This mutation was hypothesized to disrupt dual zinc fingers as well as one transactivating domain. The present findings lend additional support to the notion that the phenotype cannot be precisely estimated from the genotype in HDR syndrome.

Pax 2/8-regulated Gata 3 expression is necessary for morphogenesis and guidance of the nephric duct in the developing kidney

The mammalian pro- and mesonephros are transient embryonic kidneys essential for urogenital system development. The nephric (Wolffian) duct, which is a central constituent of both structures, elongates caudally along a stereotypical path to reach the hindlimb level where it induces metanephros (adult kidney) formation, while the remaining duct gives rise to the male genital tract (epidydimis, vas deferens). The transcription factors Pax2 and Pax8 are essential for the initiation of pro- and mesonephros development. In a cDNA microarray screen for genes specifically expressed in the pro/mesonephros and regulated by Pax proteins, we identified Gata3, a transcription factor gene associated with hypoparathyroidism, deafness and renal anomaly (HDR) syndrome. Gata3 is already expressed in the pronephric anlage, together with Pax2 and Pax8, suggesting that it may be a direct Pax2/8 target gene. Inactivation of Gata3 by insertion of an Ires-GFP reporter gene resulted in a massive increase in nephric duct cellularity, which was accompanied by enhanced cell proliferation and aberrant elongation of the nephric duct. Interestingly, however, the nephrogenic cord extended, with delayed kinetics, along the entire caudal path up to the level of the hindlimb bud, indicating that extension of the nephric duct and cord is controlled by different guidance cues. At the molecular level, the nephric duct of Gata3(-/-) embryos is characterized by the loss of Ret expression and signaling, which may contribute to the guidance defect of the nephric duct. Together, these results define Gata3 as a key regulator of nephric duct morphogenesis and guidance in the pro/mesonephric kidney.

Developmental control via GATA factor interplay at chromatin domains

Despite the extraordinary task of packaging mammalian DNA within the constraints of a cell nucleus, individual genes assemble into cell type-specific chromatin structures with high fidelity. This chromatin architecture is a crucial determinant of gene expression signatures that distinguish specific cell types. Whereas extensive progress has been made on defining biochemical and molecular mechanisms of chromatin modification and remodeling, many questions remain unanswered about how cell type-specific chromatin domains assemble and are regulated. This mini-review will discuss emerging studies on how interplay among members of the GATA family of transcription factors establishes and regulates chromatin domains. Dissecting mechanisms underlying the function of hematopoietic GATA factors has revealed fundamental insights into the control of blood cell development from hematopoietic stem cells and the etiology of pathological states in which hematopoiesis is perturbed.

Transcriptional control of fetal liver hematopoiesis: dominant negative effect of the overexpression of the LIM domain mutants of LMO2

OBJECTIVE

The LIM-finger protein LMO2 forms a transcription factor complex with other hematopoietic regulator proteins, such as TAL1 (SCL), LDB1, GATA1, 2, and 3, in the promoters of several erythroid genes. To elucidate the functional role of two LIM domains in LMO2, we introduced deletion or mutation in each of the LIM domains and analyzed their phenotypic effects on the hematopoietic system when overexpressed in vivo or in vitro.

MATERIALS AND METHODS

Protein interactions of LIM-modified LMO2 constructs with TAL1, LDB1, and GATAs were examined in an immunoprecipitation assay. In vivo hematopoiesis in transgenic mice with wild-type and LIM-modified Lmo2 was studied morphologically and by measuring the progenitor cells in fetal liver. Their effects on the erythroid differentiation of the dimethylsulfoxide (DMSO)-induced murine erythroleukemia (MEL) cells were evaluated.

RESULTS

Deletion of the LIM2 domain, but not of the LIM1 domain, abolished its binding of GATA proteins. Overexpression of wild-type LMO2 is known to have dominant negative inhibitory effects on erythropoietic development. Enforced expression of LMO2 constructs with mutant or absent LIM2 but with an intact LIM1 domain resulted in fetal death, small livers and hearts, and decreased hematopoiesis, as well as a hypoplastic thymus. DMSO-induced erythroid differentiation of the MEL cells was inhibited by the overexpressed LMO2 with mutant LIM2 but not by the LMO2 with modified LIM1.

CONCLUSION

Overexpression of the LMO2 with modified LIM2 inhibited hematopoiesis probably by interfering with the formation of the physiological complex or by replacing the functional LMO2 with mutants with reduced affinity to GATA proteins. In this experiment, no evident effect of the LMO2 with modified LIM1 could be observed.

GATA motifs regulate early hematopoietic lineage-specific expression of the Gata2 gene

Transcription factor GATA-2 is essential for definitive hematopoiesis, which developmentally emerges from the para-aortic splanchnopleura (P-Sp). The expression of a green fluorescent protein (GFP) reporter placed under the control of a 3.1-kbp Gata2 gene regulatory domain 5' to the distal first exon (IS) mirrored that of the endogenous Gata2 gene within the P-Sp and yolk sac (YS) blood islands of embryonic day (E) 9.5 murine embryos. The P-Sp- and YS-derived GFP(+) fraction of flow-sorted cells dissociated from E9.5 transgenic embryos contained far more CD34(+)/c-Kit(+) cells than the GFP(-) fraction did. When cultured in vitro, the P-Sp GFP(+) cells generated both immature hematopoietic and endothelial cell clusters. Detailed transgenic mouse reporter expression analyses demonstrate that five GATA motifs within the 3.1-kbp Gata2 early hematopoietic regulatory domain (G2-EHRD) were essential for GFP expression within the dorsal aortic wall, where hemangioblasts, the earliest precursors possessing both hematopoietic and vascular developmental potential, are thought to reside. These results thus show that the Gata2 gene IS promoter is regulated by a GATA factor(s) and selectively marks putative hematopoietic/endothelial precursor cells within the P-Sp.

GATA3 haploinsufficiency causes a rapid deterioration of distortion product otoacoustic emissions (DPOAEs) in mice

Human HDR (hypoparathyroidism, deafness and renal dysplasia)-syndrome is caused by haploinsufficiency of zinc-finger transcription factor GATA3. The hearing loss due to GATA3 haploinsufficiency has been shown to be peripheral in origin, but it is unclear to what extent potential aberrations in the outer hair cells (OHCs) contribute to this disorder. To further elucidate the pathophysiological mechanism underlying the hearing defect in HDR-syndrome, we investigated the OHCs in heterozygous Gata3-knockout mice at both the functional and morphological level. While the signal-to-noise ratios of distortion product otoacoustic emissions (DPOAE) in wild type mice did not change significantly during the first half-year of live, those in the heterozygous Gata3 mice decreased dramatically. In addition, both light microscopic and transmission electron microscopic analyses showed that the number of OHCs containing vacuoles was increased in the mutants. Together, these findings indicate that outer hair cell malfunctioning plays a major role in the hearing loss in HDR-syndrome.

GATA factors in Drosophila heart and blood cell development

GATA transcription factors comprise an evolutionarily conserved family of proteins that function in the specification and differentiation of various cell types during animal development. In this review, we examine current knowledge of the structure, expression, and function of the Pannier and Serpent GATA factors as they relate to cardiogenesis and hematopoiesis in the Drosophila system. We also assess the molecular and genetic characteristics of the Friend of GATA protein U-shaped, which serves as a regulator of Pannier and Serpent function in these two developmental processes.

KLF2 is essential for primitive erythropoiesis and regulates the human and murine embryonic beta-like globin genes in vivo

The Krüppel-like factors (KLFs) are a family of C2/H2 zinc finger DNA-binding proteins that are important in controlling developmental programs. Erythroid Krüppel-like factor (EKLF or KLF1) positively regulates the beta-globin gene in definitive erythroid cells. KLF2 (LKLF) is closely related to EKLF and is expressed in erythroid cells. KLF2-/- mice die between embryonic day 12.5 (E12.5) and E14.5, because of severe intraembryonic hemorrhaging. They also display growth retardation and anemia. We investigated the expression of the beta-like globin genes in KLF2 knockout mice. Our results show that KLF2-/- mice have a significant reduction of murine embryonic Ey- and beta h1-globin but not zeta-globin gene expression in the E10.5 yolk sac, compared with wild-type mice. The expression of the adult beta(maj)- and beta(min)-globin genes is unaffected in the fetal livers of E12.5 embryos. In mice carrying the entire human globin locus, KLF2 also regulates the expression of the human embryonic epsilon-globin gene but not the adult beta-globin gene, suggesting that this developmental-stage-specific role is evolutionarily conserved. KLF2 also plays a role in the maturation and/or stability of erythroid cells in the yolk sac. KLF2-/- embryos have a significantly increased number of primitive erythroid cells undergoing apoptotic cell death.

Spectroscopic and functional determination of the interaction of Pb2+ with GATA proteins

GATA proteins are transcription factors that bind GATA DNA elements through Cys4 structural zinc-binding domains and play critical regulatory roles in neurological and urogenital development and the development of cardiac disease. To evaluate GATA proteins as potential targets for lead, spectroscopically monitored metal-binding titrations were used to measure the affinity of Pb2+ for the C-terminal zinc-binding domain from chicken GATA-1 (CF) and the double-finger domain from human GATA-1 (DF). Using this method, Pb2+ coordinating to CF and DF was directly observed through the appearance of intense bands in the near-ultraviolet region of the spectrum (250-380 nm). Absorption data collected from these experiments were best fit to a 1:1 Pb2+ -CF model and a 2:1 Pb2+ -DF model. Competition experiments using Zn2+ were used to determine the absolute affinities of Pb2+ for these proteins. These studies reveal that Pb2+ forms tight complexes with cysteine residues in the zinc-binding sites in GATA proteins, beta1Pb = 6.4 (+/- 2.0) x 10(9) M(-1) for CF and beta2 = 6.3 (+/- 6.3) x 10(19) M(-2) for Pb(2+)2-DF, and within an order of magnitude of the affinity of Zn2+ for these proteins. Furthermore, Pb2+ was able to displace bound Zn2+ from CF and DF. Upon addition of Pb2+, GATA shows a decreased ability to bind to DNA and subsequently activate transcription. Therefore, the DNA binding and transcriptional activity of GATA proteins are most likely to be targeted by Pb2+ in cells and tissues that sequester Pb2+ in vivo, which include the brain and the heart.

The murine placenta contains hematopoietic stem cells within the vascular labyrinth region

In the midgestation murine embryo, several major vascular tissues contain hematopoietic stem cell (HSC) activity. These include the aorta-gonad-mesonephros region (AGM), yolk sac, and fetal liver. Recently, the placenta was demonstrated to harbor hematopoietic progenitors, but it was not examined for HSC activity. We demonstrate here that the placenta also harbors adult-repopulating HSCs. Placental HSCs begin to be detected at embryonic day (E) 11, and HSC numbers increase dramatically between E11 and E12, exceeding the numbers in the circulating embryonic blood. Furthermore, all placental HSC activity is restricted to the GFP+ fraction of cells in Ly-6A (Sca-1) GFP transgenic embryos. Cells coexpressing GFP and endothelial markers CD34 and CD31 are found in the embryonic vasculature of the placental labyrinth. Moreover, placental cell expression of other HSC markers and transcription factors suggests that HSC emergence may occur in the placenta, as has been proposed for other embryonic hematopoietic sites.

Genomic organization and sequence variation of the human integrin subunit alpha8 gene (ITGA8)

The integrin alpha8 is highly expressed during kidney and lung development. alpha8-deficient mice display abnormal renal development suggesting that alpha8 plays a critical role in organogenesis. Therefore, it would be of considerable interest to understand the genomic structure, localization and sequence variation of the alpha8 gene. Using FISH and genomic database analysis, we show that alpha8 gene maps to chromosome 10p13 and consists of >200 kbp organized into 30 exons. Examination of 47 individuals from two different ethnic groups (European and African descent) identified 286 varying sites. The diversity of alpha8 is comparable to that of other regions within the human genome. Eight of the varying sites were located in the coding regions: six resulted in nonsynonymous substitutions of which two lead to non-conservative changes in protein. None of the sites showed significant deviation from Hardy-Weinberg equilibrium. We mapped the coding region single nucleotide polymorphisms (SNPs) onto a model of the predicted alpha8 structure and found all the SNPs were located in the "calf" of the extracellular domain. In the European population, the linkage disequilibrium statistic D' showed three blocks of relatively non-recombinant regions in the alpha8 gene while the African population showed more evidence of recombination. The observed patterns of the linkage disequilibrium statistic R2 suggest that a large number of sites will need to be genotyped to ensure coverage of the entire gene for genetic association studies. Identification of the sequence variation will allow genetic association studies of alpha8 in kidney and lung disease.

A placenta-specific enhancer of the human syncytin gene

The cis- and trans-acting factors that are critical for placenta-specific expression of the human syncytin gene are unknown. We identified a 146-base pair (bp) region of the 5'-flanking region of the human syncytin gene from nt-294 to -148 that is essential for basal gene expression in human BeWo and JEG3 choriocarcinoma cell lines but not in hepatoblastoma and kidney cell lines. Ligation of the 146-bp fragment to a SV40 promoter or a human beta-globin minimal promoter markedly enhanced promoter activity in the placenta cells but not in the liver and kidney cells. DNase I footprint assays indicated that nuclear extracts from BeWo cells but not HepG2 cells protected four regions (FP1-FP4) of the 146-bp fragment. Site-directed mutagenesis of an SP1-binding site in FP3 and a GATA-binding site in FP4 significantly repressed promoter activity in the placenta cells. Overexpression of SP1 (Sp1 transcription factor) and GATA2 (GATA binding protein 2) and GATA3 induced syncytin promoter activity but had little or no effect on the activities of syncytin promoter fragments containing mutations in the SP1- and GATA-binding sites. GATA2 and -3 mRNA levels increased markedly during spontaneous in vitro differentiation of human cytotrophoblast cells when the cytotrophoblast cells fused to form a syncytium. These findings strongly suggest that the 146-bp region of the 5'-flanking region (nt-294/-148) of the human syncytin gene acts as a placenta-specific enhancer. Binding of SP1 and GATA family members to this enhancer is critical for cell-specific expression of the syncytin gene.

Gene expression analysis of Gata3-/- mice by using cDNA microarray technology

Transcription factor Gata3 is implicated in the formation of autosomal dominant hypoparathyroidism, sensorineural deafness, and renal anomaly (HDR) syndrome. We pursued to identify the potential Gata3 target genes by profiling the gene expression pattern in E9.5 Gata3-/- mouse embryos. Altogether four independent microarray hybridizations were carried out on NIA Mouse15K cDNA arrays. We discovered two hundred and sixty one genes that are downregulated in Gata3 mutant embryos at E9.5 (with a minimal 2.0-fold change). The majority of the differentially expressed genes belong to two functional groups--genes involved in transcription regulation and cellular signaling. One of the genes discovered to be downregulated in Gata3 mutant embryos was tumor suppressor gene Disabled 2. The validity of this finding was checked by using the whole mount in situ hybridization technology. This study revealed that the sites, where Dab2 is downregulated in the mutant embryos partly overlap with the Gata3 expression domains, including the mid-embryo region, branchial arches and facio-acoustic (VII-VIII) neural crest complex. This is the first time when tumor supressor gene Dab2 is shown to be implicated in the defective phenotype of Gata3 mutant mice.

Immune responses to Nippostrongylus brasiliensis and tuberculin protein in GATA-3-transgenic mice

GATA-3 appears to be key to the Th2 response. However, few in vivo experiments have examined the function of GATA-3 in Th1 and Th2 immune responses. We developed two lines of GATA-3-transgenic (Tg) mice harboring the SRalpha or lck promoters and examined the Th2 immune responses of mice infected with the intestinal nematode Nippostrongylus brasiliensis and the Th1 responses with purified derivative of tuberculin (PPD) immunization. Numbers of peripheral blood eosinophils in all GATA-3-Tg mice increased 10- to 20-fold after primary infection with N. brasiliensis and 25-100-fold after secondary infection. The number of eosinophils in infected GATA-3-Tg mice was significantly higher than that in infected control littermates. Total IgE levels after primary infection in GATA-3-Tg mice were 8-450-fold increased, which was significantly higher than those of control mice. Mesenteric lymph node cells of infected GATA-3-Tg mice upon stimulation with N. brasiliensis antigen secreted more IL-5 and IL-13 than those of control mice. However, production of IL-4 and IFN-gamma were comparable between GATA-3-Tg and controls. Mice immunized with PPD were intradermally challenged with PPD to induce delayed type hypersensitivity (DTH). The amount of footpad swelling caused by the DTH reaction in GATA-3-Tg mice was significantly smaller than that of control littermates. Inguinal lymph node cells from GATA-3-Tg mice stimulated with PPD in vitro secreted more IL-5, IL-10 and less IFN-gamma than those of control littermates. These results suggested that Th1 and Th2 driven conditions enhance IL-5 production in GATA-3-Tg mice through the direct binding of GATA-3 to the IL-5 promoter region. The influence of GATA-3 on IL-13, IFN-gamma and IL-10 production varied according to the stimulating conditions. However, IL-4 production was not significantly elevated in GATA-3-Tg mice, indicating that IL-4 and IL-5 production was differentially regulated in these mice.

The cell cycle associated protein, HTm4, is expressed in differentiating cellsof the hematopoietic and central nervous system in mice

HTm4 is a member of a newly defined family of human and murine proteins, the MS4 (membrane-spanning four) protein group, which has a distinctive four-transmembrane structure. MS4 protein functions include roles as cell surface signaling receptors and intracellular adapter proteins. We have previously demonstrated that HTm4 regulates the function of the KAP phosphatase, a key regulator of cell cycle progression. In humans, the expression of HTm4 is largely restricted to cells of the hematopoietic lineage, possibly reflecting a causal role for this molecule in differentiation/proliferation of hematopoietic lineage cells. In this study, we show that, like the human homologue, murine HTm4 is also predominantly a hematopoietic protein with distinctive expression patterns in developing murine embryos and in adult animals. In addition, we observed that murine HTm4 is highly expressed in the developing and adult murine nervous system, suggesting a previously unrecognized role in central and peripheral nervous system development.

Multiple, distant Gata2 enhancers specify temporally and tissue-specific patterning in the developing urogenital system

Transcription factor GATA-2 is expressed in a complex temporally and tissue-specific pattern within the developing embryo. Loss-of-function studies in the mouse showed that GATA-2 activity is first required during very early hematopoiesis. We subsequently showed that a 271-kbp yeast artificial chromosome (YAC) transgene could fully complement the loss of Gata2 hematopoietic function but that these YAC-rescued Gata2 null mutant mice die perinatally due to defective urogenital development. The rescuing YAC did not display appropriate urogenital expression of Gata2, implying the existence of a urogenital-specific enhancer(s) lying outside the boundaries of this transgene. Here we outline a coupled general strategy for regulatory sequence discovery, linking bioinformatics to functional genomics based on the bacterial artificial chromosome (BAC) libraries used to generate the mouse genome sequence. Exploiting this strategy, we screened >1 Mbp of genomic DNA surrounding Gata2 for urogenital enhancer activity. We found that the spatially and tissue-specific functions for Gata2 in the developing urogenital system are conferred by at least three separate regionally and temporally specific urogenital enhancer elements, two of which reside far 3' to the Gata2 structural gene. Including the additional enhancers that were discovered using this strategy (called BAC trap) extends the functional realm of the Gata2 locus to greater than 1 Mbp.