GATA Family Of Transcription Factors Research Articles

GATA3 inhibits proliferation and induces expression of both early and late differentiation markers in keratinocytes of the human epidermis

GATA3 belongs to the GATA transcription factor family and is a crucial regulator of lymphocyte differentiation. More recently, GATA3 was shown to be involved in skin cell lineage determination, in morphogenesis and maintenance of hair follicle keratinocytes as well as in epidermal barrier formation in mouse. In human, the potential role of GATA3 in the regulation of interfollicular epidermal homeostasis was still poorly explored. We thus investigated whether GATA3 could play a role in the regulation of proliferation and/or differentiation processes in human primary keratinocytes. We silenced the expression of GATA3 by small interfering RNA in either proliferating or differentiated human primary keratinocytes and analyzed the effect on cell proliferation and differentiation. We showed that GATA3 inhibition increased cell number, BrdU incorporation and expression of the proliferation markers PCNA and Ki67, demonstrating that GATA3 can inhibit keratinocyte proliferation. Moreover, GATA3 seems to be able to induce keratinocyte differentiation since its silencing leads to a decrease of both early and late differentiation markers such as Keratins 1 and 10, Involucrin and Loricrin. Our results demonstrate that GATA3 transcription factor inhibits proliferation and induces differentiation of primary keratinocytes, which suggest that it may regulate human interfollicular epidermal renewal.

Concurrent Loss Of Ezh2 and Tet2 Cooperates In The Pathogenesis Of Myelodysplastic Disorders,

Inactivating somatic mutations in polycomb-group (PcG) genes such as EZH2 and ASXL1occur frequently in patients with myelodysplastic syndromes (MDS), myeloproliferative neoplasm (MPN) and MDS/MPN overlap disorders. While these mutations suggest a tumor suppressor function of polycomb repressive complex 2 (PRC2)-related genes in these diseases, both the impact of each PcG mutation and its interplay with coinciding mutations remain largely unknown. To understand the contribution of inactivating PcG mutations to the development of myeloid malignancies, genomic DNA from 119 patients with MDS and related neoplasms were analyzed for mutations in EZH2, ASXL1 and TET2 by high-throughput sequencing. Inactivating mutations in EZH2 and ASXL1 were detected in 8.4 and 16.8 % of patients, respectively. Moreover, 3.4 % of patients had deletion of EZH2 (located at 7q36) associated with -7 and 7q- chromosomal abnormalities. Notably, 57.1 % of these EZH2 mutations coexisted with TET2 mutations. Conversely, 34.8 % of patients with TET2 mutations had coexisting EZH2mutations. In order to understand the impact of inactivating EZH2 mutations and concurrent EZH2 and TET2 mutations on hematopoiesis, we crossed Cre-ERT;Ezh2fl/fl mice and Tet2 gene trap mice (Tet2KD/KD). Due to the early time of death in Tet2KD/KD mice and a necessity to exclude the influence of the loss of Tet2 and Ezh2 in BM niche cells, we transplanted E14.5 fetal liver cells from Cre-ERT control (WT), Cre-ERT;Tet2KD/KD, Cre-ERT;Ezh2fl/fl and Cre-ERT;Tet2KD/KDEzh2fl/fl CD45.2 mice into lethally irradiated CD45.1 recipient mice and deleted Ezh2 by intraperitoneal injection of tamoxifen at 4 weeks post-transplantation. During a long observation period, we found that Ezh2Δ/Δ mice developed MDS/MPN and half of the mice died by 10 months post-transplantation. They showed myeloproliferative features characterized by extramedullary hematopoiesis in the spleen as evident from splenomegaly with a marked increase in LSK cells. They were anemic and showed increased apoptosis in Ter119highCD71high erythroblasts in the BM, suggesting ineffective erythropoiesis, a feature compatible with myelodysplastic disorders. Ezh2Δ/Δ mice also showed dysplasia of myeloid cells, including a pseudo Pelger-Huët anomaly. To our surprise, concurrent deletion of Tet2 and Ezh2 significantly shortened the latency of disease development of not only MDS/MPN but also MDS, and all of the compound mice died of pneumonia by 10 months. Tet2KD/KDEzh2Δ/Δ MDS/MPN mice showed myeloproliferative features, including monocytosis and/or splenomegaly with extramedullary hematopoiesis. In contrast, Tet2KD/KDEzh2Δ/Δ MDS mice did not show obvious myeloproliferative features, but showed a trend of pancytopenia. The proportion of Annexin V+ cells in CD71highTer119high erythroblasts was significantly higher in both MDS/MPN and MDS mice compared to their WT counterparts, implicating enhanced apoptosis as a cause of anemia. Furthermore, myeloid dysplasia was more pronounced in these mice compared to Ezh2Δ/Δmice. Gene set enrichment analysis with microarray data showed that the Myc module was significantly enriched in Ezh2Δ/Δ LSK cells and became highly enriched in Tet2KD/KDEzh2Δ/Δ LSK cells during the development of MDS/MPN and MDS in Tet2KD/KDEzh2Δ/Δ mice. As expected, all of the PRC2 gene sets (Ezh2 targets and Ezh1 targets) showed a trend of positive enrichment in Ezh2Δ/Δ and Tet2KD/KDEzh2Δ/Δ LSK cells. Notably, however, Ezh1 targets became negatively enriched in Tet2KD/KDEzh2Δ/Δ LSK cells during the development of myelodysplastic disorders. ChIP-seq and microarray analysis data showed that upon deletion of Ezh2, a series of potential PcG related target oncogenes, such as Hmga2 and Pbx3, became derepressed in LSK cells. On the other hand, key developmental regulator genes, such as genes encoding homeobox, paired-box, T-box, forkhead and Gata family transcription factors and zinc finger DNA-binding proteins, were kept transcriptionally repressed by the compensatory action of Ezh1. Our findings provide the first evidence of the tumor suppressor function of EZH2 and demonstrate the cooperative effect of concurrent gene mutations in the pathogenesis of myelodysplastic disorders. These two models represent novel, genetically accurate models of myelodysplastic disorders amenable to epigenomic as well as preclinical therapeutic studies. Disclosures: No relevant conflicts of interest to declare.

Prognostic value of the trichorhinophalangeal syndrome-1 (TRPS-1), a GATA family transcription factor, in early-stage breast cancer

BackgroundTRPS-1 is a new GATA transcription factor that is differentially expressed in breast cancer (BC) where it been found recently to regulate epithelial-to-mesenchymal transition (EMT). Patients and methodsWe carried out a quantitative immunohistochemistry (qIHC) analysis of TRPS-1 expression in 341 primary-stage I–III BC samples in relation to patient clinical characteristics as well as its prognostic value, especially in an estrogen receptor-positive (ER+) subgroup. ResultsHigher TRPS-1 expression was significantly associated with a number of clinical and pathological characteristics as well as with improved overall survival (OS) and disease-free survival (DFS). Among stage I/II ER+ BC patients who received endocrine therapy alone, those with high TRPS-1 expression had significantly longer OS and DFS. There was also a strong association between TRPS-1 levels and the EMT marker E-cadherin in the ER+ invasive ductal carcinoma cases. Analysis of gene expression data on a panel of BC lines found that TRPS-1 expression was low or absent in BC lines having enriched mesenchymal features. ConclusionsOur data indicated that TRPS-1 is an independent prognostic marker in early-stage BC and a new EMT marker that can distinguish patients with ER+ BC who will respond longer to adjuvant endocrine therapy.

GATA augments GNRH-mediated increases in Adcyap1 gene expression in pituitary gonadotrope cells

Pituitary adenylate cyclase-activating polypeptide 1 (PACAP or ADCYAP1) regulates gonadotropin biosynthesis and secretion, both alone and in conjunction with GNRH. Initially identified as a hypothalamic-releasing factor, ADCYAP1 subsequently has been identified in pituitary gonadotropes, suggesting it may act as an autocrine-paracrine factor in this tissue. GNRH has been shown to increase pituitary Adcyap1 gene expression through the interaction of CREB and jun/fos with CRE/AP1 cis-elements in the proximal promoter. In these studies, we were interested in identifying additional transcription factors and cognate cis-elements which regulate Adcyap1 gene promoter activity and chose to focus on the GATA family of transcription factors known to be critical for both pituitary cell differentiation and gonadotropin subunit expression. By transient transfection and electrophoretic mobility shift assay analysis, we demonstrate that GATA2 and GATA4 stimulate Adcyap1 promoter activity via a GATA cis-element located at position -191 in the rat Adcyap1 gene promoter. Furthermore, we show that addition of GATA2 or GATA4 significantly augments GNRH-mediated stimulation of Adcyap1 gene promoter activity in the gonadotrope LβT2 cell line. Conversely, blunting GATA expression with specific siRNA inhibits the ability of GNRH to stimulate ADCYAP1 mRNA levels in these cells. These data demonstrate a complex interaction between GNRH and GATA on ADCYAP1 expression, providing important new insights into the regulation of gonadotrope function.

GATA transcription factors: New key regulators in pancreas organogenesis.

GATA transcription factors: New key regulators in pancreas organogenesis.

Functionally distinct Gata3/Chd4 complexes coordinately establish Th2 cell identity. (P1340)

Abstract Gata3 is a GATA family transcription factor that controls differentiation of naïve CD4 T cells into T helper (Th) 2 cells. However, it is unknown how Gata3 simultaneously activates Th2-specific genes while repressing those of other Th lineages. Here we show that Chd4 (chromodomain helicase DNA-binding protein 4) forms a complex with Gata3 in Th2 cells that both activates Th2 cytokine transcription and represses the Th1 cytokine IFNγ. We define a Gata3/Chd4/p300 transcriptional activation complex at the Th2 cytokine loci and a Gata3/Chd4-NuRD repression complex at the Tbx21 locus in Th2 cells. We also demonstrated a physiological role for Chd4 in Th2-dependent inflammation in an in vivo model of asthmatic inflammation. Thus, Gata3/Chd4 forms functionally distinct complexes, which mediate both positive and negative gene regulation to facilitate Th2 cell differentiation.

Functionally distinct Gata3/Chd4 complexes coordinately establish T helper 2 (Th2) cell identity

GATA binding protein 3 (Gata3) is a GATA family transcription factor that controls differentiation of naïve CD4 T cells into T helper 2 (Th2) cells. However, it is unknown how Gata3 simultaneously activates Th2-specific genes while repressing those of other Th lineages. Here we show that chromodomain helicase DNA-binding protein 4 (Chd4) forms a complex with Gata3 in Th2 cells that both activates Th2 cytokine transcription and represses the Th1 cytokine IFN-γ. We define a Gata3/Chd4/p300 transcriptional activation complex at the Th2 cytokine loci and a Gata3/Chd4-nucleosome remodeling histone deacetylase repression complex at the Tbx21 locus in Th2 cells. We also demonstrate a physiological role for Chd4 in Th2-dependent inflammation in an in vivo model of asthmatic inflammation. Thus, Gata3/Chd4 forms functionally distinct complexes, which mediate both positive and negative gene regulation to facilitate Th2 cell differentiation.

Roles of trichorhinophalangeal syndrome-1 gene in normal breast development and breast cancer

GATA transcription factor family members have been found to involve in the growth and differentiation of mammary gland. Among them GATA-3 is regarded as the most critical regulator involving the tumorigenesis of breast cancer (BC). Recently, trichorhinophalangeal syndrome-1 gene (TRPS-1), a new GATA family member, has been identified to be highly prevalent in breast cancer. Compared with ER-negative breast cancer, the expression of TRPS-1 is higher in ER-positive breast cancer and was significantly correlates with estrogen receptor, progesterone receptor, and GATA-3, indicating it may serve as a ductal epithelial cell-specific regulator in the differentiation of breast ductal epithelial cells. Studies have shown that miR221/222 is able to downregulate the expression of an epithelial cell marker E-cadherin by targeting TRPS-1, resulting in mammary epithelial cells transition to mesenchymal cell (EMT). In addition, it has been well accepted that, and the Science and Technology Bureau of Jiaxing (2012AY1071-2)TRPS-1 plays a role in the differentiation of several other cell types including kidney nephric mesenchymal cells, columnar chondrocytes, and osteoclasts, indicating that TRPS-1 involves in mesenchymal-to-epithelial cell transition (MET). In this article, we summarize the roles of GATA transcription factor TRPS-1 in ductal epithelial cells and the roles of its gene and protein expressions in predicting the prognosis of breast cancer.

Mesenchymal stem cells alleviate TNBS-induced colitis by modulating inflammatory and autoimmune responses

To investigate the potential therapeutic effects of mesenchymal stem cells (MSCs) in inflammatory bowel disease (IBD), we transplanted MSCs into an experimental model of IBD. A rectal enema of trinitrobenzene sulfonic acid (TNBS) (100 mg/kg body weight) was administered to female BALB/c mice. Bone marrow mesenchymal stem cells (BMSCs) were derived from male green fluorescent protein (GFP) transgenic mice and were transplanted intravenously into the experimental animals after disease onset. Clinical activity scores and histological changes were evaluated. GFP and Sex determining region Y gene (SRY) expression were used for cell tracking. Ki67 positive cells and Lgr5-expressing cells were determined to measure proliferative activity. Inflammatory response was determined by measuring the levels of different inflammatory mediators in the colon and serum. The inflammatory cytokines included tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), interleukin-2 (IL-2), IL-6, IL-17, IL-4, IL-10, and transforming growth factor (TGF-β). Master regulators of Th1 cells (T-box expressed in T cells, T-bet), Th17 cells (retinoid related orphan receptor gamma(t), RORγt), Th2 cells (GATA family of transcription factors 3, GATA3) and regulatory T cells (forkhead box P3, Foxp3) were also determined. Systemic infusion of GFP-BMSCs ameliorated the clinical and histopathologic severity of colitis, including body weight loss, diarrhea and inflammation, and increased survival (P < 0.05). The cell tracking study showed that MSCs homed to the injured colon. MSCs promoted proliferation of intestinal epithelial cells and differentiation of intestinal stem cells (P < 0.01). This therapeutic effect was mainly mediated by down-regulation of both Th1-Th17-driven autoimmune and inflammatory responses (IL-2, TNF-α, IFN-γ, T-bet; IL-6, IL-17, RORγt), and by up-regulation of Th2 activities (IL-4, IL-10, GATA-3) (P < 0.05). MSCs also induced activated CD4(+)CD25(+)Foxp3(+) regulatory T cells (TGF-β, IL-10, Foxp3) with a suppressive capacity on Th1-Th17 effecter responses and promoted Th2 differentiation in vivo (P < 0.05). MSCs are key regulators of immune and inflammatory responses and may be an attractive candidate for cell-based therapy of IBD.

Reduced TOR signaling sustains hyphal development inCandida albicansby lowering Hog1 basal activity

Candida albicans is able to undergo reversible morphological changes between yeast and hyphal forms in response to environmental cues. This morphological plasticity is essential for its pathogenesis. Hyphal development requires two temporally linked changes in promoter chromatin, which is sequentially regulated by temporarily clearing the transcription inhibitor Nrg1 upon activation of cAMP/protein kinase A and promoter recruitment of the histone deacetylase Hda1 under reduced target of rapamycin (Tor1) signaling. The GATA family transcription factor Brg1 recruits Hda1 to promoters for sustained hyphal development, and BRG1 expression is a readout of reduced Tor1 signaling. How Tor1 regulates BRG1 expression is not clear. Using a forward genetic screen for mutants that can sustain hyphal elongation in rich media, we found hog1, ssk2, and pbs2 mutants of the HOG mitogen-activated protein kinase pathway to express BRG1 irrespective of rapamycin. Furthermore, rapamycin lowers the basal activity of Hog1 through the functions of the two Hog1 tyrosine phosphatases Ptp2 and Ptp3. Active Hog1 represses the expression of BRG1 via the transcriptional repressor Sko1 as Sko1 disassociates from the promoter of BRG1 in the hog1 mutant or in rapamycin. Our data suggest that reduced Tor1 signaling lowers Hog1 basal activity via Hog1 phosphatases to activate BRG1 expression for hyphal elongation.

BRG1 and NRG1 form a novel feedback circuit regulating Candida albicans hypha formation and virulence

In the opportunistic fungal pathogen Candida albicans both cellular morphology and the capacity to cause disease are regulated by the transcriptional repressor Nrg1p. One of the genes repressed by Nrg1p is BRG1, which encodes a putative GATA family transcription factor. Deletion of both copies of this gene prevents hypha formation. We discovered that BRG1 overexpression is sufficient to overcome Nrg1p-mediated repression and drive the morphogenetic shift from yeast to hyphae even in the absence of environmental stimuli. We further observed that expression of BRG1 influences the stability of the NRG1 transcript, thus controlling filamentation through a feedback loop. Analysis of this phenomenon revealed that BRG1 expression is required for the induction of an antisense NRG1 transcript. This is the first demonstration of a role for mRNA stability in regulating the key C. albicans virulence trait: the ability to form hyphae.

Characterization of PIR1, a GATA family transcription factor involved in iron responses in the white-rot fungus Phanerochaete chrysosporium

Iron, although toxic in excess, is an essential element for biological systems. Therefore, its homeostasis is of critical importance and tight mechanisms participate in its acquisition by microbial organisms. Lately, the relevance of this metal for biomass conversion by wood-degrading fungi has been gaining increasing attention. Iron plays a critical role as cofactor of key enzymes such as lignin and manganese peroxidases in lignin-degrading white-rot fungi, while Fe(II) also serves a pivotal role in Fenton reactions that are central in cellulose depolymerization by brown-rotters. It has been hypothesized that multicopper oxidases with ferroxidase activity might participate in controlling the bioavailability of iron in the hyphal proximity, fine-tuning Fenton chemistry and balancing lignin versus cellulose degradation. In order to further explore the dynamics of iron regulation in the well known white-rot fungus Phanerochaete chrysosporium, we analyzed the mRNA levels of the multicopper oxidases genes (mcos) in response to iron supplementation, confirming down-regulation of their expression in response to this metal. To gain a better understanding on the transcriptional mechanisms mediating this effect, we searched for a gene encoding a GATA-type transcription factor with homology to URBS1, the major transcriptional regulator of iron homeostasis in Ustilago maydis. Due to the limitation of experimental tools in P. chrysosporium, the alleged Phanerochaete iron regulator (PIR1) was studied by complementation of a Neurospora SRE/URBS1-deficient strain, where phenotypic and molecular characteristics of this transcriptional regulator could be easily assessed. In addition, using a genome-wide in silico strategy, we searched for putative cis-acting iron-responsive elements in P. chrysosporium. Some of the identified genes showed reduced transcript levels after 30min in the presence of the metal, consistent with an SRE/URBS1-mediated mechanism, and suggesting a broad effect of iron on the regulation of several cellular processes.

A GATA Transcription Factor Recruits Hda1 in Response to Reduced Tor1 Signaling to Establish a Hyphal Chromatin State in Candida albicans

Candida albicans is an important opportunistic fungal pathogen of immunocompromised individuals. One critical virulence attribute is its morphogenetic plasticity. Hyphal development requires two temporally linked changes in promoter chromatin, which is sequentially regulated by temporarily clearing the transcription inhibitor Nrg1 upon activation of the cAMP/PKA pathway and promoter recruitment of the histone deacetylase Hda1 under reduced Tor1 signaling. Molecular mechanisms for the temporal connection and the link to Tor1 signaling are not clear. Here, through a forward genetic screen, we report the identification of the GATA family transcription factor Brg1 as the factor that recruits Hda1 to promoters of hypha-specific genes during hyphal elongation. BRG1 expression requires both the removal of Nrg1 and a sub-growth inhibitory level of rapamycin; therefore, it is a sensitive readout of Tor1 signaling. Interestingly, promoters of hypha-specific genes are not accessible to Brg1 in yeast cells. Furthermore, ectopic expression of Brg1 cannot induce hyphae, but can sustain hyphal development. Nucleosome mapping of a hypha-specific promoter shows that Nrg1 binding sites are in nucleosome free regions in yeast cells, whereas Brg1 binding sites are occupied by nucleosomes. Nucleosome disassembly during hyphal initiation exposes the binding sites for both regulators. During hyphal elongation, Brg1-mediated Hda1 recruitment causes nucleosome repositioning and occlusion of Nrg1 binding sites. We suggest that nucleosome repositioning is the underlying mechanism for the yeast-hyphal transition. The hypha-specific regulator Ume6 is a key downstream target of Brg1 and functions after Brg1 as a built-in positive feedback regulator of the hyphal transcriptional program to sustain hyphal development. With the levels of Nrg1 and Brg1 dynamically and sensitively controlled by the two major cellular growth pathways, temporal changes in nucleosome positioning during the yeast-to-hypha transition provide a mechanism for signal integration and cell fate specification. This mechanism is likely used broadly in development.

Cognitive-Behavioral Stress Management Reverses Anxiety-Related Leukocyte Transcriptional Dynamics

Chronic threat and anxiety are associated with pro-inflammatory transcriptional profiles in circulating leukocytes, but the causal direction of that relationship has not been established. This study tested whether a cognitive-behavioral stress management (CBSM) intervention targeting negative affect and cognition might counteract anxiety-related transcriptional alterations in people confronting a major medical threat. One hundred ninety-nine women undergoing primary treatment of stage 0-III breast cancer were randomized to a 10-week CBSM protocol or an active control condition. Seventy-nine provided peripheral blood leukocyte samples for genome-wide transcriptional profiling and bioinformatic analyses at baseline, 6-month, and 12-month follow-ups. Baseline negative affect was associated with >50% differential expression of 201 leukocyte transcripts, including upregulated expression of pro-inflammatory and metastasis-related genes. CBSM altered leukocyte expression of 91 genes by >50% at follow-up (group × time interaction), including downregulation of pro-inflammatory and metastasis-related genes and upregulation of type I interferon response genes. Promoter-based bioinformatic analyses implicated decreased activity of NF-κB/Rel and GATA family transcription factors and increased activity of interferon response factors and the glucocorticoid receptor as potential mediators of CBSM-induced transcriptional alterations. In early-stage breast cancer patients, a 10-week CBSM intervention can reverse anxiety-related upregulation of pro-inflammatory gene expression in circulating leukocytes. These findings clarify the molecular signaling pathways by which behavioral interventions can influence physical health and alter peripheral inflammatory processes that may reciprocally affect brain affective and cognitive processes.

Inherited Thrombocytopenia Due toGATA-1Mutations

The GATA family of transcription factors, including the founding member, GATA-1, have an important role in gene regulation. GATA-1 is integral to successful hematopoiesis. A wide variety of mutations in GATA-1 affect its function, as well as its interaction with its cofactors (especially Friend of GATA) and the genes upon which GATA-1 acts. Here we review the known mutations, focusing on the specific alterations within the amino acid sequence, the resulting effect on hematopoietic development, and the clinical manifestations that result. Attention is also paid to the relationship between Trisomy 21, also known as Down syndrome, and the phenomenon of a truncated GATA-1, named GATA-1s. The evidence for specific interaction between GATA-1 and chromosome 21, which may explain the correlation between these two mutations, is briefly reviewed.

GATA5 interacts with GATA4 and GATA6 in outflow tract development

Members of the GATA family of transcription factors are critical regulators of heart development and mutations in 2 of them, GATA4 and GATA6 are associated with outflow tract and septal defects in human. The heart expresses 3 GATA factors, GATA4, 5 and 6 in a partially overlapping pattern. Here, we report that compound Gata4/ Gata5 and Gata5/ Gata6 mutants die embryonically or perinatally due to severe congenital heart defects. Almost all Gata4 +/− Gata5 +/− mutant embryos have double outlet right ventricles (DORV), large ventricular septal defects (VSD) as well as hypertrophied mitral and tricuspid valves. Only 25% of double compound Gata4/ Gata5 heterozygotes survive to adulthood and these mice have aortic stenosis. Compound loss of a Gata5 and a Gata6 allele also leads to DORVs associated with subaortic VSDs. Expression of several transcription factors important for endocardial and myocardial cell differentiation, such as Tbx20, Mef2c, Hey1 and Hand2, was reduced in compound heterozygote embryos. These findings suggest the existence of important genetic interactions between Gata5 and the 2 other cardiac GATA factors in endocardial cushion formation and outflow tract morphogenesis. The data identify GATA5 as a potential genetic modifier of congenital heart disease and provide insight for elucidating the genetic basis of an important class of human birth defects.

Cap2-HAP Complex Is a Critical Transcriptional Regulator That Has Dual but Contrasting Roles in Regulation of Iron Homeostasis in Candida albicans

Iron homeostasis is highly regulated in organisms across evolutionary time scale as iron is essential for various cellular processes. In a computational screen, we identified the Yap/bZIP domain family in Candida clade genomes. Cap2/Hap43 is essential for C. albicans growth under iron-deprivation conditions and for virulence in mouse. Cap2 has an amino-terminal bipartite domain comprising a fungal-specific Hap4-like domain and a bZIP domain. Our mutational analyses showed that both the bZIP and Hap4-like domains perform critical and independent functions for growth under iron-deprivation conditions. Transcriptome analysis conducted under iron-deprivation conditions identified about 16% of the C. albicans ORFs that were differentially regulated in a Cap2-dependent manner. Microarray data also suggested that Cap2 is required to mobilize iron through multiple mechanisms; chiefly by activation of genes in three iron uptake pathways and repression of iron utilizing and iron storage genes. The expression of HAP2, HAP32, and HAP5, core components of the HAP regulatory complex was induced in a Cap2-dependent manner indicating a feed-forward loop. In a feed-back loop, Cap2 repressed the expression of Sfu1, a negative regulator of iron uptake genes. Cap2 was coimmunoprecipitated with Hap5 from cell extracts prepared from iron-deprivation conditions indicating an in vivo association. ChIP assays demonstrated Hap32-dependent recruitment of Hap5 to the promoters of FRP1 (Cap2-induced) and ACO1 (Cap2-repressed). Together our data indicates that the Cap2-HAP complex functions both as a positive and a negative regulator to maintain iron homeostasis in C. albicans.

GATA transcription factors regulate LHβ gene expression

The GATA family of transcription factors are critical determinants of cell differentiation as well as regulation of adult gene expression throughout the reproductive axis. Within the anterior pituitary gland, GATA factors have been shown to increase glycoprotein α-subunit gene promoter activity; however, nothing has been known about the impact of these factors on expression of the gonadotropin β-subunits. In this study, we demonstrate expression of both GATA2 and GATA4 in primary mouse gonadotropes and the gonadotrope cell line, LβT2. Based on the transient transfection in fibroblast cells, GATA factors increase LH β-subunit gene (LHβ) promoter activity alone and in synergy with the orphan nuclear receptors steroidogenic factor-1 (SF-1) and liver receptor homologue-1 (LRH-1). The GATA response was localized to a DNA regulatory region at position -101 in the rat LHβ gene promoter which overlaps with a previously described cis-element for pituitary homeobox-1 (Pitx1) and is flanked by two SF-1/LRH-1 regulatory sites. As determined by gel shift, GATA and Pitx1 can compete for binding to this element. Furthermore, mutation analysis revealed a requirement for both the GATA/Pitx1 and the SF-1/LRH-1 cis-elements in order to achieve synergy. These studies identify a novel role for GATA transcription factors in the pituitary and reveal additional molecular mechanisms by which precise modulation of LHβ gene expression can be achieved.

Highlights in DD

“Highlights” calls attention to exciting advances in developmental biology that have recently been reported in Developmental Dynamics. Development is a broad field encompassing many important areas. To reflect this fact, the section spotlights significant discoveries that occur across the entire spectrum of developmental events and problems: from new experimental approaches, to novel interpretations of results, to noteworthy findings utilizing different developmental organisms. Stem cells on demand (Facultative Stem Cells in Liver and Pancreas: Fact and Fancy by Kilangsungla Yanger and Ben Z. Stanger, Dev Dyn 240:521–529) Video on demand enables the viewer to watch what he wants (feel-good movies), when he wants (while sick in bed). Similarly facultative stem cells (FSCs)—differentiated cells that become multipotent—enable an organ to generate what it needs (stem cells) when it needs them (following injury). In a famous example, salamander limb loss triggers mature mesenchymal cells to de-differentiate and then re-differentiate into the myriad cell types needed to reconstitute a new limb. In this provocative review, Yanger and Stanger discuss the controversy surrounding FSC-based regeneration in mammals. Presented in detail are two putative FSC populations, oval cells that appear following hepatotoxin-based injury of the liver, and ductal cells in the regenerating pancreas. The authors discuss what is known about the existence, origins, and potential of these cell populations, and do not shy away from pointing out potential flaws in published results. What becomes clear is thatsettling the controversy is paramount. Defining what allows a differentiated cell to become a stem cell “on demand” could profoundly impact regeneration research and our understanding of the multipotent state. GATA get it right (Different Requirements for GATA Factors in Cardiogenesis Are Mediated by Non-Canonical Wnt Signaling by Boni A. Afouda and Stefan Hoppler, Dev Dyn 240:649–662) Most people hate to be mistaken for their sibling. After all, everyone deserves to be recognized as an individual. The same is true for the GATA family of transcription factors, collectively known for their roles in endoderm and cardiac development. To distinguish functions of GATA 4, 5, and 6 in cardiac development—a task that has proven to be difficult in vivo—Afouda and Hoppler employ animal cap explants that have been induced to undergo cardiogenesis. Expression of early and late cardiogenic markers were used to assess effects of morpholino depletion and ectopic induction of GATA 4-6 in such cultured explants. The combined results point to overlapping roles for GATA4 and 6 in early cardiogenesis and cardiomyocyte differentiation, and for GATA5 in differentiation. Their differential roles are further supported by the finding that ectopic expression of Wnt 11b, or the downstream non-canonical Wnt component Disheveled, rescues GATA4 and 6, but not GATA5 morphants. These results suggest that GATA4 and 6 uniquely function through the non-canonical Wnt11b pathway. Parsing the specific roles of GATAs, and their pathways may help to devise effective stem cell therapies. It is only when an individual's unique abilities are understood that they can be used to their full potential. Live action BMP signaling (Dynamic Analysis of BMP-Responsive Smad Activity in Live Zebrafish Embryos by Derek W. Laux, Jennifer A. Febbo, and Beth L. Roman, Dev Dyn 240:682–694; Dynamic Smad-Mediated BMP Signaling Revealed Through Transgenic Zebrafish by Ross F. Collery and Brian A. Link, Dev Dyn 240:712–722) Those investigating sites of bone morphogenetic protein (BMP) activity, an important regulator of development and disease, have traditionally been relegated to piecing together static images of fixed, stained tissues. Knowing that live action beats stop motion, two groups have generated fluorescent transgenic reporter lines that display live BMP signaling in the optically clear zebrafish. Their reporters are based on conserved BMP-responsive elements (BRE) from the mouse inhibitor of differentiation-1 (Id1) promoter, that are responsive to the BMP effectors, Smad 1/5/8. The reporters effectively replicate many well-known sites of Smad 1/5/8 activity, respond to genetic and chemical manipulations of the BMP pathway, and potentially reveal previously uncharacterized sites of BMP action. However, they also have some limitations; the authors discuss why the reporters fail to detect some known sites of BMP activity. Regardless, the dynamic reporter lines will undoubtedly prove useful in screening for small molecules that affect BMP signaling and identifying genetic modulators of the pathway.

A Major Role for Capsule-Independent Phagocytosis-Inhibitory Mechanisms in Mammalian Infection by Cryptococcus neoformans

The antiphagocytic polysaccharide capsule of the human fungal pathogen Cryptococcus neoformans is a major virulence attribute. However, previous studies of the pleiotropic virulence determinant Gat201, a GATA family transcription factor, suggested that capsule-independent antiphagocytic mechanisms exist. We have determined that Gat201 controls the mRNA levels of ∼1100 genes (16% of the genome) and binds the upstream regions of ∼130 genes. Seven Gat201-bound genes encode for putative and known transcription factors--including two previously implicated in virulence--suggesting an extensive regulatory network. Systematic analysis pinpointed two critical Gat201-bound genes, GAT204 (a transcription factor) and BLP1, which account for much of the capsule-independent antiphagocytic function of Gat201. A strong correlation was observed between the quantitative effects of single and double mutants on phagocytosis in vitro and on host colonization in vivo. This genetic dissection provides evidence that capsule-independent antiphagocytic mechanisms are pivotal for successful mammalian infection by C. neoformans.