Human TEF-5 is preferentially expressed in placenta and binds to multiple functional elements of the human chorionic somatomammotropin-B gene enhancer

Platr4 is an early embryonic lncRNA that exerts its function downstream on cardiogenic mesodermal lineage commitment

The mammalian genome encodes thousands of long non-coding RNAs (lncRNAs), many of which are developmentally regulated and differentially expressed across tissues, suggesting their potential roles in cellular differentiation. Despite this expression pattern, little is known about how lncRNAs influence lineage commitment at the molecular level. Here, we demonstrate that perturbation of an embryonic stem cell/early embryonic lncRNA, pluripotency-associated transcript 4 (Platr4), directly influences the specification of cardiac-mesoderm-lineage differentiation. We show that Platr4 acts as a molecular scaffold or chaperone interacting with the Hippo-signaling pathway molecules Yap and Tead4 to regulate the expression of a downstream target gene, Ctgf, which is crucial to the cardiac-lineage program. Importantly, Platr4 knockout mice exhibit myocardial atrophy and valve mucinous degeneration, which are both associated with reduced cardiac output and sudden heart failure. Together, our findings provide evidence that Platr4 is required in cardiac-lineage specification and adult heart function in mice.

Regulatory genomic circuitry of human disease loci by integrative epigenomics

Annotating the molecular basis of human disease remains an unsolved challenge, as 93% of disease loci are non-coding and gene-regulatory annotations are highly incomplete^1-3. Here we present EpiMap, a compendium comprising 10,000 epigenomic maps across 800 samples, which we used to define chromatin states, high-resolution enhancers, enhancer modules, upstream regulators and downstream target genes. We used this resource to annotate 30,000 genetic loci that were associated with 540 traits⁴, predicting trait-relevant tissues, putative causal nucleotide variants in enriched tissue enhancers and candidate tissue-specific target genes for each. We partitioned multifactorial traits into tissue-specific contributing factors with distinct functional enrichments and disease comorbidity patterns, and revealed both single-factor monotropic and multifactor pleiotropic loci. Top-scoring loci frequently had multiple predicted driver variants, converging through multiple enhancers with a common target gene, multiple genes in common tissues, or multiple genes and multiple tissues, indicating extensive pleiotropy. Our results demonstrate the importance of dense, rich, high-resolution epigenomic annotations for the investigation of complex traits.

Human placental 3β-hydroxysteroid dehydrogenase/steroid Δ5,4-isomerase 1: Identity, regulation and environmental inhibitors

Human placental 3β-hydroxysteroid dehydrogenase/steroid Δ5, 4-isomerase 1 (HSD3B1), a high-affinity type I enzyme, uses pregnenolone to make progesterone, which is critical for maintenance of pregnancy. HSD3B1 is located in the mitochondrion and the smooth endoplasmic reticulum of placental cells and is encoded by HSD3B1 gene. HSD3B1 contains GATA and TEF-5 regulatory elements. Many endocrine disruptors, including phthalates, methoxychlor and its metabolite, organotins, and gossypol directly inhibit placental HSD3B1 thus blocking progesterone production. In this review, we discuss the placental HSD3B1, its gene regulation, biochemistry, subcellular location, and inhibitors from the environment.

Chromosomal architecture and placental expression of the human growth hormone gene family are targeted by pre-pregnancy maternal obesity

The human (h) placental lactogenic hormone chorionic somatomammotropin (CS) is highly produced during pregnancy and acts as a metabolic adaptor in response to maternal insulin resistance. Maternal obesity can exacerbate this "resistance", and a >75% decrease in CS RNA levels was observed in term placentas from obese vs. lean women. The genes coding for hCS ( hCS-A and hCS-B) and placental growth hormone ( hGH-V) as well as the hCS-L pseudogene and pituitary growth hormone (GH) gene ( hGH-N) are located at a single locus on chromosome 17. Three remote hypersensitive sites (HS III-V) located >28 kb upstream of hGH-N as well as local hCS gene promoter and enhancer regions are implicated in hCS gene expression. A placenta-specific chromosomal architecture, including interaction between HS III-V and hCS but not hGH gene promoters, was detected in placentas from lean women (BMI <25 kg/m²) by using the chromosome conformation capture assay. This architecture was disrupted by pre-pregnancy maternal obesity (BMI >35 kg/m²), resulting in a predominant interaction between HS III and the hGH-N promoter, which was also observed in nonplacental tissues. This was accompanied by a decrease in hCS levels, which was consistent with reduced RNA polymerase II and CCAAT/enhancer-binding protein-β association with individual hCS promoter and enhancer sequences, respectively. Thus, pre-pregnancy maternal obesity disrupts the placental hGH/CS gene locus chromosomal architecture. However, based on data from obese women who develop GDM, insulin treatment partially recapitulates the chromosomal architecture seen in lean women and positively affects hCS production, presumably facilitating prolactin receptor-related signaling by hCS.

Regulation of the Hippo Pathway Transcription Factor TEAD

The TEAD transcription factor family is best known for transcriptional output of the Hippo signaling pathway and has been implicated in processes such as development, cell growth and proliferation, tissue homeostasis, and regeneration. Our understanding of the functional importance of TEADs has increased dramatically since its initial discovery three decades ago. The majority of our knowledge of TEADs is in the context of Hippo signaling as nuclear DNA-binding proteins passively activated by Yes-associated protein (YAP) and transcriptional activator with PDZ-binding domain (TAZ), transcription coactivators downstream of the Hippo pathway. However, recent studies suggest that TEAD itself is actively regulated. Here, we highlight evidence demonstrating Hippo-independent regulation of TEADs and the potential impacts these studies may have on new cancer therapeutics.

Long-range looping of a locus control region drives tissue-specific chromatin packing within a multigene cluster

The relationships of higher order chromatin organization to mammalian gene expression remain incompletely defined. The human Growth Hormone (hGH) multigene cluster contains five gene paralogs. These genes are selectively activated in either the pituitary or the placenta by distinct components of a remote locus control region (LCR). Prior studies have revealed that appropriate activation of the placental genes is dependent not only on the actions of the LCR, but also on the multigene composition of the cluster itself. Here, we demonstrate that the hGH LCR 'loops' over a distance of 28 kb in primary placental nuclei to make specific contacts with the promoters of the two GH genes in the cluster. This long-range interaction sequesters the GH genes from the three hCS genes which co-assemble into a tightly packed 'hCS chromatin hub'. Elimination of the long-range looping, via specific deletion of the placental LCR components, triggers a dramatic disruption of the hCS chromatin hub. These data reveal a higher-order structural pathway by which long-range looping from an LCR impacts on local chromatin architecture that is linked to tissue-specific gene regulation within a multigene cluster.

Characterization of the transcriptional activation domains of human TEF3-1 (transcription enhancer factor 3 isoform 1)

TEF3-1 (transcription enhancer factor 3 isoform 1) is a human transcriptional factor, which has a N-terminal TEA/ATTS domain supposedly for DNA binding and C-terminal PRD and STY domains for transcriptional activation. Taking advantage of the efficient reporter design of yeast two-hybrid system, we characterized the TEF3-1 domains in activating gene expression. Previously study usually mentioned that the C-terminal domain of TEF3-1 has the transcriptional activity, however, our data shows that the peptides TEF3-11-66 and TEF3-1197-434 functioned as two independent activation domains, suggesting that N-terminal domain of TEF3-1 also has transcriptional activation capacity. Additionally, more deletions of amino acids 197-434 showed that only the peptides TEF3-1197-265 contained the minimum sequences for the C-terminal transcriptional activation domain. The protein structure is predicted to contain a helix-turn-helix structure in TEF3-11-66 and four β sheets in TEF3-1197-265. Finally, after the truncated fragments of TEF3-1 were expressed in HUVEC cells, the whole TEF3-1 and the two activation domains could increase F-actin stress fiber, cell proliferation, migration and targeted gene expression. Further analysis and characterization of the activation domains in TEF3-1 may broaden our understanding of the gene involved in angiogenesis and other pathological processes.

Tissue specific CTCF occupancy and boundary function at the human growth hormone locus

The robust and tissue-specific activation of the human growth hormone (hGH) gene cluster in the pituitary and placenta constitutes an informative model for analysis of gene regulation. The five-gene hGH cluster is regulated by two partially overlapping sets of DNase I hypersensitive sites (HSs) that constitute the pituitary (HSI, II, III and V) and placental (HSIII, IV, and V) locus control regions (LCRs). The single placenta-specific LCR component, HSIV, is located at −30 kb to the cluster. Here we generate a series of hGH/BAC transgenes specifically modified to identify structural features of the hGH locus required for its appropriate placental expression. We find that placental specificity is dependent on the overall multigene configuration of the cluster whereas the distance between the cluster and its LCR impacts the level of placental expression. We further observe that a major function of the placental hGH LCR is to insulate the transgene locus from site-of-integration effects. This insulation activity is linked to placenta-specific occupancy of the chromatin architectural protein, CTCF, at HSIV. These data reveal a remarkable combination of structural configurations and regulatory determinants that must work in concert to insure robust and tightly controlled expression from a complex multigene locus.

CCAAT-enhancer-binding protein β (C/EBPβ) and downstream human placental growth hormone genes are targets for dysregulation in pregnancies complicated by maternal obesity

Human chorionic somatomammotropin (CS) and placental growth hormone variant (GH-V) act as metabolic adaptors in response to maternal insulin resistance, which occurs in "normal" pregnancy. Maternal obesity can exacerbate this "resistance," suggesting that CS, GH-V, or transcription factors that regulate their production might be targets. The human CS genes, hCS-A and hCS-B, flank the GH-V gene. A significant decrease in pre-term placental CS/GH-V RNA levels was observed in transgenic mice containing the CS/GH-V genes in a model of high fat diet (HFD)-induced maternal obesity. Similarly, a decrease in CS/GH-V RNA levels was detected in term placentas from obese (body mass index (BMI) ≥ 35 kg/m(2)) versus lean (BMI 20-25 kg/m(2)) women. A specific decrease in transcription factor CCAAT-enhancer-binding protein β (C/EBPβ) RNA levels was also seen with obesity; C/EBPβ is required for mouse placenta development and is expressed, like CS and GH-V, in syncytiotrophoblasts. Binding of C/EBPβ to the CS gene downstream enhancer regions, which by virtue of their position distally flank the GH-V gene, was reduced in placenta chromatin from mice on a HFD and in obese women; a corresponding decrease in RNA polymerase II associated with CS/GH-V promoters was also observed. Detection of decreased endogenous CS/GH-V RNA levels in human placental tumor cells treated with C/EBPβ siRNA is consistent with a direct effect. These data provide evidence for CS/GH-V dysregulation in acute HFD-induced obesity in mouse pregnancy and chronic obesity in human pregnancy and implicate C/EBPβ, a factor associated with CS regulation and placental development.

Early onset pre-eclampsia is associated with altered DNA methylation of cortisol-signalling and steroidogenic genes in the placenta

Placental cortisol is inactivated in normotensive pregnancies, but is frequently present in pre-eclampsia associated placentae. Since glucocorticoids are strongly associated with the programming of long-term health, we assessed DNA methylation of genes involved in cortisol signalling and bioavailability, and hormonal signalling in the placenta of normotensive and hypertensive pregnancies. Candidate genes/CpG sites were selected through analysis of Illumina Infinium HumanMethylation450 BeadChip array data on control (n = 19) and early onset pre-eclampsia (EOPET; n = 19) placental samples. DNA methylation was further quantified by bisulfite pyrosequencing in a larger cohort of control (n = 111) cases, in addition to EOPET (n = 19), late onset pre-eclampsia (LOPET; n = 18) and normotensive intrauterine growth restriction (nIUGR; n = 13) cases. DNA methylation (percentage points) was increased at CpG sites within genes encoding the glucocorticoid receptor (NR3C1 exon 1D promoter; +8.46%; P<0.01) and corticotropin releasing hormone (CRH) binding protein (CRHBP intron 3; +9.14%; P<0.05), and decreased within CRH (5' UTR; -4.30%; P = 0.11) in EOPET-associated placentae, but not in LOPET nor nIUGR cases, compared to controls. Differential DNA methylation was not observed among groups at the 11β-hydroxysteroid dehydrogenase type 2 (HSD11B2) gene promoter. Significant hypomethylation was observed in pre-eclampsia but not nIUGR placentae for steroidogenic genes, including CYP11A1 (exon1; EOPET; -9.66%; P<0.00001, and LOPET; -5.77%; P<0.001), 3β-hydroxy-delta-5-steroid dehydrogenase type 1 (HSD3B1 exon 2; EOPET; -12.49%; P<0.00001, and LOPET; -6.88%; P<0.001), TEA domain family member 3 (TEAD3 intron 1; EOPET; -12.56%; P<0.00001) and CYP19 (placental-specific exon 1.1 promoter; EOPET; -10.62%, P<0.0001). These data represent dysregulation of the placental epigenome in pre-eclampsia related to genes involved in maintaining the hormonal environment during pregnancy and highlights particular susceptibility in the early onset syndrome.

Genetic and environmental factors influencing the Placental Growth Factor (PGF) variation in two populations

Placental Growth Factor (PGF) is a key molecule in angiogenesis. Several studies have revealed an important role of PGF primarily in pathological conditions (e.g.: ischaemia, tumour formation, cardiovascular diseases and inflammatory processes) suggesting its use as a potential therapeutic agent. However, to date, no information is available regarding the genetics of PGF variability. Furthermore, even though the effect of environmental factors (e.g.: cigarette smoking) on angiogenesis has been explored, no data on the influence of these factors on PGF levels have been reported so far. Here we have first investigated PGF variability in two cohorts focusing on non-genetic risk factors: a study sample from two isolated villages in the Cilento region, South Italy (N=871) and a replication sample from the general Danish population (N=1,812). A significant difference in PGF mean levels was found between the two cohorts. However, in both samples, we observed a strong correlation of PGF levels with ageing and sex, men displaying PGF levels significantly higher than women. Interestingly, smoking was also found to influence the trait in the two populations, although differently. We have then focused on genetic risk factors. The association between five single nucleotide polymorphisms (SNPs) located in the PGF gene and the plasma levels of the protein was investigated. Two polymorphisms (rs11850328 and rs2268614) were associated with the PGF plasma levels in the Cilento sample and these associations were strongly replicated in the Danish sample. These results, for the first time, support the hypothesis of the presence of genetic and environmental factors influencing PGF plasma variability.

Identification of functional CCAAT/enhancer-binding protein and Ets protein binding sites in the human chorionic somatomammotropin enhancer sequences

The human chorionic somatomammotropin (CS) A and B genes (listed as CSH1 and CSH2 in the HUGO database) are highly expressed in placenta. A 241 bp potent enhancer, nucleotides (nts) 1-241, located at the 3' end of the CS-B gene (CS-Benh) stimulates promoter activity specifically in placental trophoblast cells in vitro. Strong activity is exerted by a 23 bp element within the CS-Benh (nts 117-139), shown to interact with transcription enhancer factor (TEF) members of the transcription enhancer activator (TEA) DNA-binding domain-containing family. An identical TEF element is present in the homologous (97.5%) CS-Aenh; however, a few nucleotide differences suppress its activity. Previously, we identified regulatory sequences distinct from the TEF element within an 80 bp modulatory domain (nts 1-80) in the CS-Benh. Using structural and functional assays we now show that CCAAT/enhancer-binding protein (C/EBP) binding sites exist in the 80 bp modulatory domains of both enhancers, and an Elk-1 binding site exists in the modulatory domain of the CS-Aenh. C/EBPα or C/EBPβ strongly repressed CSp.CAT activity but stimulated CSp.CAT.CS-Benh activity. In contrast, the equivalent CS-A enhancer sequences were unable to relieve promoter repression. Elk-1 overexpression also resulted in differential effects on the CS-Aenh versus CS-Benh. Finally, we provide evidence for the association of C/EBPβ with the CS-A and CS-B genes in human placental chromatin, including differential involvement of C/EBPβ with the CS-Aenh versus the CS-Benh, and therefore consistent with the notion that these are regions of regulatory significance in vivo. We conclude that members of the C/EBP and Ets families can differentially modulate CS-Benh and CS-Aenh activity.

Reexamining the DNA target selectivity of Scalloped

Selector proteins are transcription factors that coordinate the formation and identity of organs and appendages. The proper formation of these tissues requires the selector proteins to regulate the expression of a large set of genes. Many selector proteins are involved in regulating multiple developmental processes, yet it is not completely clear how they are able to activate different sets of genes in a tissue-specific manner. An association with cofactors is thought to be one method by which enhancer selectivity is achieved. During wing development the selector protein Scalloped (SD) interacts with the cofactor Vestigial (VG). This interaction leads to the activation of a specific set of downstream wing genes. Herein, data are presented indicating that the switch in binding selectivity is likely achieved by VG altering the general affinity that the SD protein has for DNA. The decreased affinity for DNA is compensated for by the fact that the VG protein forms a complex containing two SD proteins. These two properties ensure that the SD–VG complex is able to bind only to enhancers that have two consecutive binding sites. Furthermore, data are presented that indicate that the function of the two terminal domains of the VG protein is not restricted to activating transcription and promoting the recruitment of two SD proteins.

TEAD1 inhibits prolactin gene expression in cultured human uterine decidual cells

Forced overexpression of TEAD1 in human uterine fibroblast (HUF) and human endometrial stromal cells markedly inhibited prolactin promoter activity in both cell types in a dose-dependent manner, with maximal inhibition of greater than 90%. Conversely, the knockdown of TEAD1 expression in HUF cells with a TEAD1 siRNA resulted in a 75-80% increase in prolactin mRNA levels (p<0.01) compared to control cells exposed to a scrambled nonsense RNA. Mutagenesis of the putative TEAD site inhibited basal promoter activity by about 80%. However, mutagenesis of the TEAD site did not prevent TEAD1-induced inhibition of promoter activity; and the transcription activity of a minimal promoter fragment lacking a putative TEAD binding site was repressed by overexpression of TEAD1. Taken together, these findings suggest that the TEAD binding site on the prolactin promoter is important for the maintenance of basal prolactin promoter activity and that overexpression of TEAD1 has a dominant-negative effect on prolactin promoter activity, probably by interacting directly with other transcription factors.

Transcriptional regulation of phosphatidylcholine biosynthesis

Phosphatidylcholine biosynthesis in animal cells is primarily regulated by the rapid translocation of CTP:phosphocholine cytidylyltransferase alpha between a soluble form that is inactive and a membrane-associated form that is activated. Until less than 10 years ago there was no information on the transcriptional regulation of phosphatidylcholine biosynthesis. Research has identified the transcription factors Sp1, Rb, TEF4, Ets-1 and E2F as enhancing the expression of the cytidylyltransferase and Net as a factor that represses cytidylyltransferase expression. Key transcription factors involved in cholesterol or fatty acid metabolism (SREBPs, LXRs, PPARs) do not have a major role in transcriptional regulation of the cytidylyltransferase. Rather than being linked to cholesterol or energy metabolism, regulation of the cytidylyltransferase is linked to the cell cycle, cell growth and differentiation. Transcriptional regulation of phospholipid biosynthesis is more elegantly understood in yeast and involves responses to inositol, choline and zinc in the culture medium.

Effect of Kidney-replenishing herb on the indoleamine 2,3-dioxygenase of human syncytiotrophoblasts cultured in vitro and the balance of helper T-cell cytokines

BACKGROUND

There is complicated pathogeny involved in spontaneous abortion. At present, the focus of study is on the interface between mother and fetus, the trophoblasts. Indoleamine 2,3-dioxygenase (IDO) is the first and regulatory enzyme in the major route of l-tryptophan catabolism, which induces immunosuppression of T lymphocytes. In the present study we investigated the effect of Kidney-replenishing herb on the expression and activity of IDO in human syncytiotrophoblasts cultured in vitro and the balance of helper T cell (Th) cytokines.

METHODS

Syncytiotrophoblasts were cultured in vitro for 24, 48 or 72 h, with either control serum or serum made from Kidney-replenishing herb, without or with different concentrations of the IDO inhibitor 1-methyltryptophan (1-MT). Reverse transcription-polymerase chain reaction was applied to analyze the IDO mRNA transcription of syncytiotrophoblasts and Western blotting was applied to determine the expression of IDO protein in syncytiotrophoblasts. The concentration of interleukin-10 and interferon-gamma in co-culture medium of syncytiotrophoblasts and decidual T lymphocytes was determined by enzyme-linked immunosorbent assay. High-performance liquid chromatography was used to determine the concentration of kynurenine (Kyn) and tryptophan (Tyr) in the co-culture medium, and the ratio of Kyn/Try was used to assess IDO activity.

RESULTS

IDO mRNA and protein were detected in human syncytiotrophoblasts cultured in vitro. The IDO inhibitor 1-MT caused the balance of Th cytokines to depart from type 2; when IDO activity was inhibited, Kidney-replenishing herb improved the expression of IDO mRNA and protein, promoted IDO activity and caused the balance of Th cytokines depart from type 1.

CONCLUSION

Kidney-replenishing herb improves the expression of IDO mRNA and protein, promotes IDO activity to an appropriate value, resumes the balance of Th cytokines and regulates maternofetal tolerance.

Vestigial-like-2b (VITO-1b) and Tead-3a (Tef-5a) expression in zebrafish skeletal muscle, brain and notochord

The vestigial gene has been shown to control skeletal muscle formation in Drosophila and the related Vestigial-like 2 (Vgl-2) protein plays a similar role in mice. Vgl-family proteins are thought to regulate tissue-specific gene expression by binding to members of the broadly expressed Scalloped/Tef/TEAD transcription factor family. Zebrafish have at least four Vgl genes, including two Vgl-2s, and at least three TEAD genes, including two Tead3s. We describe the cloning and expression of one member from each family in the zebrafish. A novel gene, vgl-2b, with closest homology to mouse and human vgl-2, is expressed transiently in nascent notochord and in muscle fibres as they undergo terminal differentiation during somitogenesis. Muscle cells also express a TEAD-3 homologue, a possible partner of Vgl-2b, during myoblast differentiation and early fibre assembly. Tead-3a is also expressed in rhombomeres, eye and epiphysis regions.

Epigenetic activation of the human growth hormone gene cluster during placental cytotrophoblast differentiation

The hGH cluster contains a single human pituitary growth hormone gene (hGH-N) and four placenta-specific paralogs. Activation of the cluster in both tissues depends on 5' remote regulatory elements. The pituitary-specific locus control elements DNase I-hypersensitive site I (HSI) and HSII, located 14.5 kb 5' of the cluster (position -14.5), establish a continuous domain of histone acetylation that extends to and activates hGH-N in the pituitary gland. In contrast, histone modifications in placental chromatin are restricted to the more 5'-remote HSV-HSIII region (kb -28 to -32) and to the placentally expressed genes in the cluster, with minimal modification between these two regions. These data predict distinct modes of hGH cluster gene activation in the pituitary and placenta. Here we used cell culture models to track structural changes at the hGH locus through placental-gene activation. The data revealed that this process was initiated in primary cytotrophoblasts by histone H3K4 di- and trimethylation and H4 acetylation restricted to HSV and to the individual placental-gene repeat (PGR) units within the cluster. Later stages of transcriptional induction were accompanied by enhancement and extension of these modifications and by robust H3 acetylation at HSV, at HSIII, and throughout the placental-gene regions. These data suggested that elements restricted to HSIII-HSV regions and each individual PGR might be sufficient for activation of the hCS genes. This model was tested by comparing hCS transgene expression in the placentas of mouse embryos carrying a full hGH cluster to that in placentas in which the HSIII-HSV region was directly linked to the individual hCS-A PGR unit. The findings indicate that the HSIII-HSV region and the PGR units, although targeted for initial chromatin structural modifications, are insufficient to activate gene expression and that this process is dependent on additional, as-yet-unidentified chromatin determinants.

Insights into transcription enhancer factor 1 (TEF-1) activity from the solution structure of the TEA domain

Transcription enhancer factor 1 is essential for cardiac, skeletal, and smooth muscle development and uses its N-terminal TEA domain (TEAD) to bind M-CAT elements. Here, we present the first structure of TEAD and show that it is a three-helix bundle with a homeodomain fold. Structural data reveal how TEAD binds DNA. Using structure-function correlations, we find that the L1 loop is essential for cooperative loading of TEAD molecules on to tandemly duplicated M-CAT sites. Furthermore, using a microarray chip-based assay, we establish that known binding sites of the full-length protein are only a subset of DNA elements recognized by TEAD. Our results provide a model for understanding the regulation of genome-wide gene expression during development by TEA/ATTS family of transcription factors.

The Transcription Factor PLA-1/SKN-1A is Expressed in Human Placenta and Regulates the Placental Lactogen-3 Gene Expression

Here we report the selective expression of two POU transcription factor genes, PLA-1 and OCT-1, in human placenta and choriocarcinoma cell lines JAR, JEG-3 and BeWo. Pla-1 protein binds to a POU-consensus DNA sequence in the human placental lactogen-3 (PL-3) promoter and it is capable of trans-activating its transcription up to 18-fold. Other tissue-specific or ubiquitous POU transcription factors such as Pit-1/GHF-1 or Oct-1 showed none or low levels of trans-activation of the PL-3 promoter. In addition, we identified an unique and highly charged region in the N-terminal portion of Pla-1 protein required for full trans-activation of the PL-3 promoter.

Transcription enhancer factor-5 and a GATA-like protein determine placental-specific expression of the Type I human 3beta-hydroxysteroid dehydrogenase gene, HSD3B1

The enzyme 3beta-hydroxysteroid dehydrogenase/isomerase (3betaHSD) is required for the biosynthesis of all active steroid hormones. It exists as multiple isoforms in humans and rodents, each a product of a distinct gene. Two isoforms, 3betaHSD I and II, are expressed in a tissue-specific manner in humans. 3betaHSD I is the only isoform expressed in the placenta, where it is required for the biosynthesis of progesterone and thus essential for the maintenance of pregnancy. We recently identified two transcription factors, activating protein-2gamma (AP-2gamma) and the homeodomain protein, distaless-3 (Dlx-3), that are expressed in both human and mouse trophoblast cells that were shown to be required for trophoblast-specific expression of the orthologous murine 3betaHSD, 3betaHSD VI. Although we identified specific binding sites for AP-2gamma and Dlx-3 in the distal promoter of the human 3betaHSD I gene, HSD3B1, it was found that these transcription factors were not involved in determining placental-specific expression of human 3betaHSD I. Instead, a 53-bp placental-specific enhancer element located between -2570 and -2518 of the HSD3B1 promoter was identified. Within this 53-bp element, two potential placental transcription factor binding sites were found. EMSAs with a 20-bp oligonucleotide containing these two potential placental-specific binding sites identified one of the binding sites specific for the transcription enhancer factor (TEF)-5, which is highly expressed in human placenta and in placental choriocarcinoma-derived JEG-3 cells and the other overlapping binding site, specific for a GATA-like protein. Site-specific mutations in either the TEF-5 binding site or in the GATA binding site, each resulted in complete loss of enhancer activity. The data indicate that TEF-5 and the GATA-like protein act in a coordinate manner to determine the placental-specific expression of the human 3betaHSD I enzyme and therefore are critical for placental progesterone production required for the maintenance of pregnancy.

VITO-1 is an essential cofactor of TEF1-dependent muscle-specific gene regulation

The expression of several muscle-specific genes is partially or completely regulated by MCAT elements, which bind members of the TEF family of transcription factors. TEF1 itself is unable to activate reporter plasmids bearing TEF1-binding sites, suggesting that additional bridging or co-activating factors are necessary to allow interaction of TEF1 with the transcriptional machinery. In addition, none of the known TEF genes are exclusively expressed in the cardiac or skeletal muscle lineage to account for the muscle-specific expression of MCAT-dependent genes. Here we describe that VITO-1, a new SID (scalloped interaction domain)-containing protein, binds to TEF1 in vitro and strongly stimulates transcription of a MCAT reporter plasmid together with TEF-1. Since VITO-1 is predominantly expressed in the skeletal muscle lineage, it might serve as an essential transcriptional intermediary factor to promote muscle-specific expression via MCAT cis-regulatory elements. Although VITO-1 alone is not sufficient to initiate myogenic conversion of 10T1/2 fibroblastic cells, it enhanced MyoD-mediated myogenic conversion. In addition, interference with VITO-1 expression by siRNA attenuated differentiation of C2C12 muscle cells and MyoD-dependent myogenesis in 10T1/2 cells. We conclude that VITO-1 is a crucial new cofactor of the muscle regulatory programme.

Identification of E-box factor TFE3 as a functional partner for the E2F3 transcription factor

Various studies have demonstrated a role for E2F proteins in the control of transcription of genes involved in DNA replication, cell cycle progression, and cell fate determination. Although it is clear that the functions of the E2F proteins overlap, there is also evidence for specific roles for individual E2F proteins in the control of apoptosis and cell proliferation. Investigating protein interactions that might provide a mechanistic basis for the specificity of E2F function, we identified the E-box binding factor TFE3 as an E2F3-specific partner. We also show that this interaction is dependent on the marked box domain of E2F3. We provide evidence for a role for TFE3 in the synergistic activation of the p68 subunit gene of DNA polymerase alpha together with E2F3, again dependent on the E2F3 marked box domain. Chromatin immunoprecipitation assays showed that TFE3 and E2F3 were bound to the p68 promoter in vivo and that the interaction of either E2F3 or TFE3 with the promoter was facilitated by the presence of both proteins. In contrast, neither E2F1 nor E2F2 interacted with the p68 promoter under these conditions. We propose that the physical interaction of TFE3 and E2F3 facilitates transcriptional activation of the p68 gene and provides strong evidence for the specificity of E2F function.

Regulatory transcription factors controlling function and differentiation of human trophoblast--a review

In transgenic mice, homozygous mutations of trophoblast-specific transcription factors such as Hand1, Mash-2, I-mfa or GCM1 revealed their key regulatory roles in induction, maintenance or differentiation of distinct placental trophoblast subpopulations in vivo. Descriptive studies have shown that several of these factors are also expressed in the human placenta, suggesting that the molecular mechanisms governing trophoblast differentiation could be similar in mice and men. While an increasing number of putative developmental regulators are being identified in the human placenta, little information is available regarding whether the particular factors play an essential role in trophoblast differentiation processes such as formation of anchoring villi, placental bed invasion or syncytialization. However, expression of abundant trophoblast-specific products such as hormones can be regarded as a hallmark of differentiation, suggesting that the factors controlling their transcription could also be involved in the developmental processes of the placenta. Indeed, studies in different model systems revealed that the human homologues of murine trophoblast-specific transcriptional regulators interact with the promoter regions of typical placental genes such as aromatase P450 (CYP19), chorionic gonadotrophin (CG) or placental lactogen (PL). Additionally, the unique combination of more broadly distributed transcription factors of the Sp or Ap-2 protein family in a particular trophoblast cell type is required to govern mRNA expression in a differentiation-dependent manner. Here, we will summarize our present knowledge on these individual transcription factors that are involved in human trophoblast function and differentiation.

Inhibition of the TEF/TEAD transcription factor activity by nuclear calcium and distinct kinase pathways

Transcription enhancer factor (TEF/TEAD) is a family of four transcription factors that share a common TEA-DNA binding domain and are involved in similar cellular functions, such as cell differentiation and proliferation. All adult tissues express at least one of the four TEAD genes, so this family of transcription factors may be of widespread importance, yet little is known about their regulation. Here we examine the factors that regulate TEAD activity in CHO cells. RT-PCR indicated the presence of TEAD-1, TEAD-3, and both isoforms of TEAD-4, but not TEAD-2. Quantitative measurements showed that TEAD-4 is most abundant, followed by TEAD-3, then TEAD-1. We examined the relative effects of nuclear and cytosolic Ca(2+) on TEAD activity, since TEAD proteins are localized to the nucleus and since free Ca(2+) within the nucleus selectively regulates transcription in some systems. Chelation of nuclear but not cytosolic Ca(2+) increased TEAD activity two times above control. Inhibition of mitogen-activated protein kinase (MAPK) also increased TEAD activity, while cAMP decreased TEAD activity, and protein kinase C had no effect. Together, these results show that nuclear Ca(2+), MAPK, and cAMP each negatively regulate the activity of the TEAD transcription factor.

The human transcription factor activation protein-2 gamma (AP-2gamma): gene structure, promoter, and expression in mammary carcinoma cell lines

Human activation protein-2 gamma (hAP-2gamma) is a key developmental transcription factor. It has been implicated in mammary carcinogenesis through its regulation of HER-2/neu proto-oncogene and estrogen receptor gene The hAP-2gamma gene is located on human chromosome 20q13.2. We cloned this gene, deduced its genomic structure, and mapped and analyzed its promoter. The hAP-2gamma gene contains seven exons. Primer extension analysis and 5'-rapid amplification of complementary DNA ends studies show that there is a single transcription start site 232 nt upstream of the translational start codon. The promoter lacks canonical binding sites for basal transcription factors such as TATA and CCAAT boxes, but contains a cluster of CpG islands and may rely on an initiator element for transcription. Deletion analyses of the promoter and chloramphenicol acetyl transferase reporter gene assays indicate that the sequence between -746 and -575 is important for its expression in mammary carcinoma cell lines. The hAP-2gamma gene is marginally activated in these cells suggesting that increased transcription partly contributes to its abundance. Architecture of the gene and promoter strikingly resembles that of hAP-2alpha, which is located on a different chromosome, suggesting a cognate origin. hAP-2alpha and hAP-2gamma have some common and some distinct roles in cells, and are likely the remarkable results of gene duplication, translocation and functional divergence through evolution.

TEF-1 transcription factors regulate activity of the mouse mammary tumor virus LTR

The mouse mammary tumor virus long terminal repeat (LTR) is a potent transcriptional enhancer. We identified several putative binding sites for the TEF-1 family of transcription factors (TEF-1, RTEF-1, DTEF-1, and ETF) in the proximal negative regulatory element of the LTR. Gel mobility shift assays revealed strong TEF-1 factor binding to one site using nuclear extracts from CV-1 cells and from the human breast cancer cell line MCF-7. Mutation of this site increased basal activity of the LTR. In transient transfection assays, TEF-1 squelched the basal LTR activity and completely abrogated the response to the glucocorticoid dexamethasone. RTEF-1 and DTEF-1 had little effect on the basal activity, whereas ETF activated the LTR. These TEF-1 factors also interfered with the response to dexamethasone. Taken together, our results reveal an important new role for TEF-1 factors in regulating MMTV LTR activity and suggest that TEF-1 factors might participate in mammary tumorigenesis.

Mouse DTEF-1 (ETFR-1, TEF-5) is a transcriptional activator in alpha 1-adrenergic agonist-stimulated cardiac myocytes

alpha(1)-Adrenergic signaling in cardiac myocytes activates the skeletal muscle alpha-actin gene through an MCAT cis-element, the binding site of the transcriptional enhancer factor-1 (TEF-1) family of transcription factors. TEF-1 accounts for more than 85% of the MCAT binding activity in neonatal rat cardiac myocytes. Other TEF-1 family members account for the rest. Although TEF-1 itself has little effect on the alpha(1)-adrenergic activation of skeletal muscle alpha-actin, the related factor RTEF-1 augments the response and is a target of alpha(1)-adrenergic signaling. Here, we examined another TEF-1 family member expressed in cardiac muscle, DTEF-1, and observed that it also augmented the alpha(1)-adrenergic response of skeletal muscle alpha-actin. A DTEF-1 peptide-specific antibody revealed that endogenous DTEF-1 accounts for up to 5% of the MCAT binding activity in neonatal rat cardiac myocytes. A TEF-1/DTEF-1 chimera suggests that alpha(1)-adrenergic signaling modulates DTEF-1 function. Orthophosphate labeling and immunoprecipitation of an epitope-tagged DTEF-1 showed that DTEF-1 is phosphorylated in vivo. alpha(1)-Adrenergic stimulation increased while phosphatase treatment lowered the MCAT binding by DTEF-1 and the endogenous non-TEF-1 MCAT-binding factor. In contrast, alpha(1)-adrenergic stimulation did not alter, and phosphatase treatment increased, MCAT binding of TEF-1 and RTEF-1. Taken together, these results suggest that DTEF-1 is a target for alpha(1)-adrenergic activation of the skeletal muscle alpha-actin gene in neonatal rat cardiac myocytes.

Cryptic MCAT enhancer regulation in fibroblasts and smooth muscle cells. Suppression of TEF-1 mediated activation by the single-stranded DNA-binding proteins, Pur alpha, Pur beta, and MSY1

An asymmetric polypurine-polypyrimidine cis-element located in the 5' region of the mouse vascular smooth muscle alpha-actin gene serves as a binding site for multiple proteins with specific affinity for either single- or double-stranded DNA. Here, we test the hypothesis that single-stranded DNA-binding proteins are responsible for preventing a cryptic MCAT enhancer centered within this element from cooperating with a nearby serum response factor-interacting CArG motif to trans-activate the minimal promoter in fibroblasts and smooth muscle cells. DNA binding studies revealed that the core MCAT sequence mediates binding of transcription enhancer factor-1 to the double-stranded polypurine-polypyrimidine element while flanking nucleotides account for interaction of Pur alpha and Pur beta with the purine-rich strand and MSY1 with the complementary pyrimidine-rich strand. Mutations that selectively impaired high affinity single-stranded DNA binding by fibroblast or smooth muscle cell-derived Pur alpha, Pur beta, and MSY1 in vitro, released the cryptic MCAT enhancer from repression in transfected cells. Additional experiments indicated that Pur alpha, Pur beta, and MSY1 also interact specifically, albeit weakly, with double-stranded DNA and with transcription enhancer factor-1. These results are consistent with two plausible models of cryptic MCAT enhancer regulation by Pur alpha, Pur beta, and MSY1 involving either competitive single-stranded DNA binding or masking of MCAT-bound transcription enhancer factor-1.

Identification and characterization of cell-specific enhancer elements for the mouse ETF/Tead2 gene

We have identified and characterized by transient transfection assays the cell-specific 117-bp enhancer sequence in the first intron of the mouse ETF (Embryonic TEA domain-containing factor)/Tead2 gene required for transcriptional activation in ETF/Tead2 gene-expressing cells, such as P19 cells. The 117-bp enhancer contains one GC-rich sequence (5'-GGGGCGGGG-3'), termed the GC box, and two tandemly repeated GA-rich sequences (5'-GGGGGAGGGG-3'), termed the proximal and distal GA elements. Further analyses, including transfection studies and electrophoretic mobility shift assays using a series of deletion and mutation constructs, indicated that Sp1, a putative activator, may be required to predominate over its competition with another unknown putative repressor, termed the GA element-binding factor, for binding to both the GC box, which overlapped with the proximal GA element, and the distal GA element in the 117-bp sequence in order to achieve a full enhancer activity. We also discuss a possible mechanism underlying the cell-specific enhancer activity of the 117-bp sequence.

The transcription factor onecut-2 controls the microphthalmia-associated transcription factor gene

Microphthalmia-associated transcription factor (MITF) is essential for melanocyte differentiation. MITF mutations are associated with some cases of Waardenburg syndrome (WS) type 2. WS is a dominantly inherited disease characterized by auditory-pigmentary defects that result from the absence of melanocytes. The lack of mutation in MITF coding sequences in some WS2 patients suggests that unidentified factors controlling MITF expression might be involved. We show here that the cut-homeodomain transcription factor Onecut-2 (OC-2) is expressed in melanocytes and binds to the MITF gene promoter. Overexpression of OC-2 in transfected cells stimulates MITF promoter activity. Mutations that prevent OC-2 binding decrease MITF promoter activity by 75%. Based on these results, we searched in 56 WS2 patients for mutations in the OC2 gene or in OC-2 binding sites in the MITF promoter, but none was found. These results show that OC-2 stimulates MITF expression and that OC2 is a candidate gene, but not a common cause, of WS.

Novel cell lines promote the discovery of genes involved in early heart development

Clonal cell lines representing early cardiomyocytes would provide valuable reagents for the dissection of the genetic program of early cardiogenesis. Here we describe the establishment and characterization of cell lines from the hearts of transgenic mice and embryos with SV40 large T antigen expressed in the heart-forming region. Ultrastructure analysis by transmission electron microscopy showed the primitive, precontractile nature of the resulting cells, with the absence of myofilaments, Z lines, and intercalated disks. Immunohistochemistry, RT-PCR, Northern blots, and oligonucleotide microarrays were used to determine the expression levels of thousands of genes in the 1H and ECL-2 cell lines. The resulting gene-expression profiles showed the transcription of early cardiomyocyte genes such as Nkx2.5, GATA4, Tbx5, dHAND, cardiac troponin C, and SM22-alpha. Furthermore, many genes not previously implicated in early cardiac development were expressed. Two of these genes, Hic-5, a possible negative regulator of muscle differentiation, and the transcription enhancing factor TEF-5 were selected and shown by in situ hybridizations to be expressed in the early developing heart. The results show that the 1H and ECL-2 cell lines can be used to discover novel genes expressed in the early cardiomyocyte.

DNA binding of TEA/ATTS domain factors is regulated by protein kinase C phosphorylation in human choriocarcinoma cells

Transcription enhancer factor 1 (TEF-1) controls the expression of a diverse set of genes. Previous studies implicated protein kinase C (PKC)-mediated signal transduction in modulating TEF function. We demonstrate that in human choriocarcinoma BeWo cells, the PKC activator 12-O-tetradecanoyl phorbol 13-acetate and PKC inhibitor bisindolylmaleimide reciprocally down- and up-regulate, respectively, TEF-mediated GGAATG core enhancer activity. In vitro TEF-1 phosphorylation with several PKC isozymes and phosphoamino acid analysis confirmed that TEF-1 is a potential PKC substrate. TEF-1.DNA complexes formed by BeWo nuclear extracts are supershifted by phosphoserine- and phosphothreonine- but not phosphotyrosine-specific antibodies, indicating that TEF-1 is phosphorylated in vivo at serine and threonine residues. The TEF-1 phosphorylation domain was localized to the third alpha-helix of the DNA binding domain and adjacent hinge region by phosphopeptide analysis. TEF-1 phosphorylation significantly reduced its DNA binding activity both in vitro and in vivo, providing a possible mechanism for the inhibitory action of PKC. Finally, BeWo cells contained abundant levels of gamma and delta PKC isoforms, and their overexpression resulted in even greater inhibition of GGAATG core enhancer activity after 12-O-tetradecanoyl phorbol 13-acetate treatment. These data strongly suggest that PKC-mediated phosphorylation is a key factor controlling TEF function.

Inhibition of touch cell fate by egl-44 and egl-46 in C. elegans

In wild-type Caenorhabditis elegans, six cells develop as receptors for gentle touch. In egl-44 and egl-46 mutants, two other neurons, the FLP cells, express touch receptor-like features. egl-44 and egl-46 also affect the differentiation of other neurons including the HSN neurons, two cells needed for egg laying. egl-44 encodes a member of the transcription enhancer factor family. The product of the egl-46 gene, two Drosophila proteins, and two proteins in human and mice define a new family of zinc finger proteins. Both egl-44 and egl-46 are expressed in FLP and HSN neurons (and other cells); expression of egl-46 is dependent on egl-44 in the FLP cells but not in the HSN cells. Wild-type touch cells express egl-46 but not egl-44. Moreover, ectopic expression of egl-44 in the touch cells prevents touch cell differentiation in an egl-46-dependent manner. The sequences of these genes and their nuclear location as seen with GFP fusions indicate that they repress transcription of touch cell characteristics in the FLP cells.

Multiprotein complex formation at the beta myosin heavy chain distal muscle CAT element correlates with slow muscle expression but not mechanical overload responsiveness

To examine the role of the beta-myosin heavy chain (betaMyHC) distal muscle CAT (MCAT) element in muscle fiber type-specific expression and mechanical overload (MOV) responsiveness, we conducted transgenic and in vitro experiments. In adult transgenic mice, mutation of the distal MCAT element led to significant reductions in chloramphenicol acetyltransferase (CAT) specific activity measured in control soleus and plantaris muscles when compared with wild type transgene beta293WT but did not abolish MOV-induced CAT specific activity. Electrophoretic mobility shift assay revealed the formation of a specific low migrating nuclear protein complex (LMC) at the betaMyHC MCAT element that was highly enriched only when using either MOV plantaris or control soleus nuclear extract. Scanning mutagenesis of the betaMyHC distal MCAT element revealed that only the nucleotides comprising the core MCAT element were essential for LMC formation. The proteins within the LMC when using either MOV plantaris or control soleus nuclear extracts were antigenically related to nominal transcription enhancer factor 1 (NTEF-1), poly(ADP-ribose) polymerase (PARP), and Max. Only in vitro translated TEF-1 protein bound to the distal MCAT element, suggesting that this multiprotein complex is tethered to the DNA via TEF-1. Protein-protein interaction assays revealed interactions between nominal TEF-1, PARP, and Max. Our studies show that for transgene beta293 the distal MCAT element is not required for MOV responsiveness but suggest that a multiprotein complex likely comprised of nominal TEF-1, PARP, and Max forms at this element to contribute to basal slow fiber expression.

Functional interaction between the p160 coactivator proteins and the transcriptional enhancer factor family of transcription factors

SRC1, initially identified as a nuclear receptor coactivator, was found to interact with a member of the transcriptional enhancer factor (TEF) family of transcription factors, TEF-4. The interaction, which occurs in both intact cells and in a cell-free system, is mediated by the highly conserved basic helix-loop-helix/Per-Arnt-Sim (bHLH-PAS) domain present in the N-terminal region of SRC1. Moreover, all three members of the p160 family of nuclear receptor coactivators, SRC1, TIF2, and RAC3, are able to potentiate transcription from a TEF response element in transient transfection experiments, and this activation requires the presence of the bHLH-PAS domain. These results suggest that the p160 proteins could be bona fide coactivators of the TEF family of transcription factors.

Cooperative binding of TEF-1 to repeated GGAATG-related consensus elements with restricted spatial separation and orientation

The human transcriptional enhancer factor (TEF) family includes TEF-1, TEF-3, TEF-4, and TEF-5. The TEFs share a highly conserved 68-amino acid TEA/ATTS DNA-binding domain, which binds to SV40 GT-IIC (GGAATG), SphI (AGTATG), SphII (AGCATG), and muscle-specific M-CAT (GGTATG) enhansons. We determined the optimal DNA-binding consensus sequence for TEF-1. Using a purified GST-TEF-1 fusion protein and a random pool of synthetic oligonucleotides, 31 independent clones were obtained after six rounds of binding site selection. DNA sequences analysis revealed that 16 clones contained direct repeats with a 3-bp spacer (DR3), and 15 clones contained a single binding site. The predominate consensus half-site was GGAATG (67%), and the other elements were of the form G(A)GA(T/C)ATG. The TEF-1 bound to the DR3 as a dimer in a cooperative manner. Cooperative binding was dependent on the spacing and orientation of the half-sites and was inhibited by deoxycholate treatment, providing evidence that protein-protein interactions were involved. The data suggest that TEF dimerization is important for its ability to modulate gene transcription.

Identification of the functional domain in the transcription factor RTEF-1 that mediates alpha 1-adrenergic signaling in hypertrophied cardiac myocytes

Cardiac myocytes respond to alpha(1)-adrenergic receptor stimulation by a progressive hypertrophy accompanied by the activation of many fetal genes, including skeletal muscle alpha-actin. The skeletal muscle alpha-actin gene is activated by signaling through an MCAT element, the binding site of the transcription enhancer factor-1 (TEF-1) family of transcription factors. Previously, we showed that overexpression of the TEF-1-related factor (RTEF-1) increased the alpha(1)-adrenergic response of the skeletal muscle alpha-actin promoter, whereas TEF-1 overexpression did not. Here, we identified the functional domains and specific sequences in RTEF-1 that mediate the alpha(1)-adrenergic response. Chimeric TEF-1 and RTEF-1 expression constructs localized the region responsible for the alpha(1)-adrenergic response to the carboxyl-terminal domain of RTEF-1. Site-directed mutagenesis was used to inactivate eight serine residues of RTEF-1, not present in TEF-1, that are putative targets of alpha(1)-adrenergic-dependent kinases. Mutation of a single serine residue, Ser-322, reduced the alpha(1)-adrenergic activation of RTEF-1 by 70% without affecting protein stability, suggesting that phosphorylation at this serine residue accounts for most of the alpha(1)-adrenergic response. Thus, these results demonstrate that RTEF-1 is a direct target of alpha(1)-adrenergic signaling in hypertrophied cardiac myocytes.

Construction of a high-resolution 2.5-Mb transcript map of the human 6p21.2-6p21.3 region immediately centromeric of the major histocompatibility complex

We have constructed a 2.5-Mb physical and transcription map that spans the human 6p21.2-6p21.3 region and includes the centromeric end of the MHC, using a combination of techniques. In total 88 transcription units including exons, cDNAs, and cDNA contigs were characterized and 60 were confidently positioned on the physical map. These include a number of genes encoding nuclear and splicing factors (Ndr kinase, HSU09564, HSRP20); cell cycle, DNA packaging, and apoptosis related [p21, HMGI(Y), BAK]; immune response (CSBP, SAPK4); transcription activators and zinc finger-containing genes (TEF-5, ZNF76); embryogenesis related (Csa-19); cell signaling (DIPP); structural (HSET), and other genes (TULP1, HSPRARD, DEF-6, EO6811, cyclophilin), as well as a number of RP genes and pseudogenes (RPS10, RPS12-like, RPL12-like, RPL35-like). Furthermore, several novel genes (a Br140-like, a G2S-like, a FBN2-like, a ZNF-like, and B1/KIAA0229) have been identified, as well as cDNAs and cDNA contigs. The detailed map of the gene content of this chromosomal segment provides a number of candidate genes, which may be involved in several biological processes that have been associated with this region, such as spermatogenesis, development, embryogenesis, and neoplasia. The data provide useful tools for synteny studies between mice and humans, for genome structure analysis, gene density comparisons, and studies of nucleotide composition, of different isochores and Giemsa light and Giemsa dark bands.

Novel human TEF-1 isoforms exhibit altered DNA binding and functional properties

The transcriptional enhancer factor-1 (TEF-1) is a member of the TEA/ATTS domain family. TEF-1 binds to GT-IIC (GGAATG), SphI (AGTATG), SphII (AGCATG), and M-CAT (GGTATG) response elements and is involved in the transactivation of a variety of genes, including the SV40 large T antigen, mammalian muscle-specific genes, and human chorionic somatomammotropin genes. Also, TEF-1 acts as a transcriptional repressor in placental cells, possibly through interaction with the TATA binding protein (TBP), preventing TBP binding to the TATA box. Here we describe the cloning, tissue-specific expression pattern, and functional characterization of two novel TEF-1 isoforms, TEF-1beta and TEF-1gamma. These isoforms most likely arise from alternative splicing of mRNA transcribed from a single gene and involve substitutions and/or insertions in a region immediately following the DNA binding domain. TEF-1beta appears to be widely distributed like the prototypic TEF-1, designated TEF-1alpha, whereas TEF-1gamma exhibits a narrower tissue-specific expression pattern that includes pancreas, kidney, and skeletal and heart muscle. The relatively limited sequence alterations among these isoforms cause significant changes in their DNA binding and transcriptional activities. TEF-1beta and TEF-1gamma bind to GT-IIC sequences with higher affinity and repress hCS promoter more efficiently than TEF-1alpha. These results suggest that each TEF-1 isoform may play unique regulatory roles in various tissues.

A GCM motif protein is involved in placenta-specific expression of human aromatase gene

A new cis-element, trophoblast-specific element 2 (TSE2) is located in the placenta-specific enhancer of the human aromatase gene that dictates its tissue-specific expression. In the minimum enhancer region, an element similar to the trophoblast-specific element (TSE), originally described for the human chorionic gonadotropin alpha-subunit gene, also exists (Yamada, K., Harada, N., Honda, S., and Takagi, Y. (1995) J. Biol. Chem. 270, 25064-25069). The co-presence of TSE and TSE2 is required to direct trophoblast-specific expression driven by a heterologous thymidine kinase promoter. A 2562-base pair cDNA clone encoding a 436-amino acid protein that binds to TSE2 was isolated from a human placental cDNA library using a yeast one-hybrid system with the TSE2 as a reporter sequence. The protein was revealed to be identical to hGCMa, a mammalian homologue of the Drosophila GCM (glia cells missing) protein. Expression of hGCMa is restricted to the placenta. The protein also binds to PLE1 in the leptin promoter among other cis-elements reported to confer placenta-specific expression, suggesting that hGCMa is a placenta-specific transcription regulator, possibly involved in the expression of multiple placenta-specific genes.

Amplifications of DNA primase 1 (PRIM1) in human osteosarcoma

We studied the involvement of PRIM1 in osteosarcoma by differential display, Northern and Southern hybridization, as well as fluorescence in situ hybridization (FISH) on interphase nuclei. In total, 22 pediatric oncology specimens were tested. PRIM1 was found to be amplified in 41% of the samples. PRIM1 is coamplified with the core 12q13 amplicon genes CDK4, SAS, and OS9, and was physically mapped very close to them. PRIM1 is therefore a new candidate for the role of a major target gene of 12q13 amplifications in human cancers. Genes Chromosomes Cancer 26:62-69, 1999.

Human placental TEF-5 transactivates the human chorionic somatomammotropin gene enhancer

Human chorionic somatomammotropin (hCS) gene expression in the placenta is controlled by an enhancer (CSEn) containing SV40-related GT-IIC and SphI/SphII enhansons. These enhancers are controlled by members of the transcription enhancer factor-1 (TEF-1) family. Recently TEF-5, whose mRNA is abundant in placenta, was shown to bind cooperatively to a unique, tandemly repeated element in CSEn2, suggesting that TEF-5 regulates CSEn activity. However, expression of TEF-5 using a cDNA lacking the 5'-untranslated region and containing a modified translation initiation site was not accompanied by CSEn activation. Using nested, degenerate PCR primers corresponding to conserved TEF domains, several novel TEF-1-related cDNAs have been cloned from a human placental cDNA library. The open reading frame of one 3033-bp clone was identical to TEF-5 and contained 300- and 1423-bp 5'- and 3'-untranslated regions, respectively. The in vitro generated approximately 53-kDa TEF-5 polypeptide binds specifically to GT-IIC and SphI/SphII oligonucleotides. Overexpression of TEF-5 in BeWo cells using the intact 3033-bp cDNA transactivates the hCS and SV40 enhancers and artificial enhancers comprised of tandemly repeated GT-IIC enhansons, but not OCT enhansons. The data demonstrate that TEF-5 is a transactivator that is likely involved in the transactivation of CSEn enhancer function. Further, the data suggest that elements within the untranslated regions, initiation site, or both control TEF-5 expression in ways that influence its transactivation function.

Identification of a placental-specific enhancer in the rat placental lactogen II gene that contains binding sites for members of the Ets and AP-1 (activator protein 1) families of transcription factors

We previously identified a 3-kb proximal 5'-flanking region of the rat placental lactogen (rPLII) gene that is important for reporter gene transcription in the rat trophoblast cell line, Rcho, and targets expression to the placentas of transgenic mice. In our current studies we have used further deletion analysis and transfection studies in Rcho and GC cells to map more precisely the locations of regulatory elements involved in this placental expression. We show that sequences between - 1435 and -765 are necessary for minimal expression in Rcho cells and that there are negative regulatory elements between -3031 to -2838 and -1729 to -1435. Most importantly, we have identified a fragment between -1793 to -1729 that is essential for expression levels characteristic of the complete 3-kb 5'-region. When linked to the herpes simplex thymidine kinase minimal promoter, this fragment acts as an enhancing element in Rcho but not GC cells. Deoxyribonuclease I (DNAse I) protection and electrophoretic mobility shift assays with nuclear extracts and in vitro translated proteins identify binding sites for members of the activator protein-1 (AP-1) and Ets families of transcription factors. Site-directed mutagenesis of the individual AP-1- and Ets-binding sites leads to a partial loss of the enhancing activity; a double AP-1/Ets mutation leads to a complete loss of activity, demonstrating the functional importance of these sites. By these criteria, putative GATA-binding sites located within the enhancing fragment are not active. These new data suggest an important role for this enhancing fragment in rPLII placental giant cell expression and are the first to implicate a member of the Ets family in the regulation of this gene family.

OC-2, a novel mammalian member of the ONECUT class of homeodomain transcription factors whose function in liver partially overlaps with that of hepatocyte nuclear factor-6

Transcription factors of the ONECUT class, whose prototype is hepatocyte nuclear factor (HNF)-6, are characterized by the presence of a single cut domain and by a peculiar homeodomain (Lannoy, V. J., Bürglin, T. R., Rousseau, G. G., and Lemaigre, F. P. (1998) J. Biol. Chem. 273, 13552-13562). We report here the identification and characterization of human OC-2, the second mammalian member of this class. The OC-2 gene is located on human chromosome 18. The distribution of OC-2 mRNA in humans is tissue-restricted, the strongest expression being detected in the liver and skin. The amino acid sequence of OC-2 contains several regions of high similarity to HNF-6. The recognition properties of OC-2 for binding sites present in regulatory regions of liver-expressed genes differ from, but overlap with, those of HNF-6. Like HNF-6, OC-2 stimulates transcription of the hnf-3beta gene in transient transfection experiments, suggesting that OC-2 participates in the network of transcription factors required for liver differentiation and metabolism.

Functional map of a placenta-specific enhancer of the human leukemia inhibitory factor receptor gene

We recently reported a placenta-specific enhancer in the human leukemia inhibitory factor receptor (LIFR) gene and now show detailed characterization of the 226-base pair enhancer (-4625/-4400 nucleotides). Four of twenty-two mutants in linker analysis showed reduced promoter activities to 45, 30, 10, and 10%, respectively. Specific binding of region A (-4617/-4602) with nuclear extract was competed by a known Oct-1 oligo and supershifted by Oct-1 antibody. Specific binding of region B (-4549/-4535) was competed by a GATA oligo, but could not be supershifted by four GATA antibodies. Nevertheless, mutagenesis showed that critical bases in region B were identical to the GATA core motif, indicating that region B may bind to a novel GATA family transcription factor. The other two adjacent regions designated as region C (-4464/-4445) showed no known consensus binding sites, and their specific placental JEG-3 nuclear extract binding was not evident in nonplacental nuclear extracts and was not competed by a trophoblast specific element (TSE), indicating that region C is a novel placenta-specific element (PSE, CATTTCCTGAACTAGTTTTT). Footprinting localized the binding boundary of PSE-binding protein (PSEB), and three Gs were found to be important for specific PSE binding. UV cross-linking showed that PSEB had a molecular mass of approximately 160 kDa, substituting the PSE with two previously reported placenta elements TSE or chorionic somatomammotropin enhancer factor 1 (CSEF-1) motifs resulted in markedly different promoter activities, indicating that PSEB is indeed different from TSE binding protein or CSEF-1. These results are the first demonstration that a novel PSE is the major element for placenta-specific enhancer activity in human LIFR gene.

Transcription factor RTEF-1 mediates alpha1-adrenergic reactivation of the fetal gene program in cardiac myocytes

Alpha1-adrenergic receptor stimulation induces cardiac myocytes to hypertrophy and reactivates many fetal genes, including beta-myosin heavy chain (betaMyHC) and skeletal alpha-actin (SKA), by signaling through myocyte-specific CAT (M-CAT) cis elements, binding sites of the transcriptional enhancer factor-1 (TEF-1) family of transcription factors. To examine functional differences between TEF-1 and related to TEF-1 (RTEF-1) in alpha1-adrenergic reactivation of the fetal program, expression constructs were cotransfected with betaMyHC and SKA promoter/reporter constructs in neonatal rat cardiac myocytes. TEF-I overexpression tended to transactivate a minimal betaMyHC promoter but significantly interfered with a minimal SKA promoter. In contrast, RTEF-1 transactivated both the minimal betaMyHC and SKA promoters. TEF-1 and RTEF-I also affected the alpha1-adrenergic response of the betaMyHC and SKA promoters differently. TEF-1 had no effect. In contrast, RTEF-1 potentiated the alpha1-adrenergic responses of the SKA promoter and of a -3.3-kb betaMyHC promoter. To determine why the promoters responded differently to TEF-1 and RTEF-1, promoters with mutated M-CAT elements were tested in the same way. The betaMyHC promoter required an intact M-CAT element to respond to TEF-1 and RTEF-1, whereas the SKA promoter M-CAT was required for the TEF-1 response but not for the RTEF-1 response, suggesting that SKA promoter-specific cofactors may be involved. By competition gel shift assay, the M-CAT of the minimal betaMyHC promoter had a lower affinity than that of the SKA promoter, which partly explains the different responses of these promoters to TEF-1. These results highlight functional differences between TEF-1 and RTEF-1 and suggest a novel function of RTEF-1 in mediating the alpha1-adrenergic response in hypertrophic cardiac myocytes.

Differential expression of the TEF family of transcription factors in the murine placenta and during differentiation of primary human trophoblasts in vitro

We describe the molecular cloning of murine (m) Transcriptional Enhancer Factor (TEF)-5 belonging to the TEF family of transcription factors. We show that mTEF-5 is specifically expressed in trophoblast giant cells and other extra-embryonic structures at early stages of development. At later stages, mTEF-5 is specifically expressed in the labyrinthine region of the placenta and in several embryonic tissues. We further show that the other mTEFs are differentially expressed in extraembryonic structures and in the mature placenta. Interestingly, human (h)TEF-5 is specifically expressed in the differentiated syncytiotrophoblast of the human term placenta and its expression is upregulated during the differentiation of cytotrophoblasts to syncytiotrophoblast in vitro, whereas that of hTEF-1 is down-regulated. Together with previous results describing hTEF-binding sites in the human placental lactogen-B gene enhancer, these novel observations support a role for hTEF-5 in the regulation of this gene. We further propose that the hTEF factors may play a more general role in placental gene regulation and development.