Expression Of COUP-TF Research Articles

SAT-358 Corticosterone Treatment during Sepsis Results in a Primary Adrenal Defect in Male Survivors

Abnormalities of adrenal gland function have been described in survivors of prolonged critical illness, but whether an acute inflammatory illness such as sepsis causes lasting changes in adrenal function is unknown. Critically ill patients with sepsis are often treated with high doses of corticosteroids for their vasoactive properties, which may also affect adrenal function. To examine the effect of sepsis and corticosteroid treatment on adrenal function, we used a naturalistic mouse model of sepsis, cecal ligation and puncture (CLP). Male and female C57Bl/6 mice (N = 20 per group, 10 male/10 female) underwent CLP or sham surgery and were treated with daily injections of either corticosterone (13 mg/kg) or vehicle for five days. Mice were maintained on a 14:10 light-dark cycle with lights on at 6 AM. Three weeks after surgery, mice were sacrificed at baseline (between 9:00 and 12:00) or after stress (6-minute swim) and blood collected for hormone measurements. Adrenal weights, adrenal gland histology, and gene expression analysis were performed on a subset of mice. The results showed that female mice had higher adrenal weights and higher plasma corticosterone, but lower plasma ACTH, when compared to males. Corticosterone and CLP had sex-dependent effects on adrenal function. Specifically, corticosterone-treated male sepsis survivors had higher morning ACTH/corticosterone ratios than the other groups without any difference in stress ACTH/corticosterone, and this group had heavier adrenal weights. These findings were not explained by adrenal histology. Gene expression analysis of male adrenals showed that corticosterone treatment increased adrenal expression of Sonic Hedgehog, Disabled-2, and COUP-TF in the sham mice, but this effect was absent in sepsis survivors. We conclude that corticosterone treatment during sepsis causes a defect in adrenal function after recovery only in males. The increased ACTH/corticosterone ratio suggests a compensatory increase in pituitary activity, while the gene expression analysis shows an absence of the normal recovery process from corticosterone treatment in the sepsis survivors. These novel findings could have clinical implications for the maintenance of appropriate adrenal function after corticosteroid treatment during acute illness. This work was supported by grants from the NIMH, NIDDK, Office of Naval Research, Hope for Depression Research Foundation, and the Brain and Behavior Research Foundation.

The Transcription Factors COUP-TFI and COUP-TFII have Distinct Roles in Arealisation and GABAergic Interneuron Specification in the Early Human Fetal Telencephalon.

In human telencephalon at 8–12 postconceptional weeks, ribonucleic acid quantitative sequencing and immunohistochemistry revealed cortical chicken ovalbumin upstream promotor-transcription factor 1 (COUP-TFI) expression in a high ventro-posterior to low anterior gradient except for raised immunoreactivity in the anterior ventral pallium. Unlike in mouse, COUP-TFI and SP8 were extensively co-expressed in dorsal sensory neocortex and dorsal hippocampus whereas COUPTFI/COUPTFII co-expression defined ventral temporal cortex and ventral hippocampus. In the ganglionic eminences (GEs) COUP-TFI immunoreactivity demarcated the proliferative zones of caudal GE (CGE), dorsal medial GE (MGE), MGE/lateral GE (LGE) boundary, and ventral LGE whereas COUP-TFII was limited to ventral CGE and the MGE/LGE boundary. Co-labeling with gamma amino butyric acidergic interneuron markers revealed that COUP-TFI was expressed in subpopulations of either MGE-derived (SOX6+) or CGE-derived (calretinin+/SP8+) interneurons. COUP-TFII was mainly confined to CGE-derived interneurons. Twice as many GAD67+ cortical cells co-labeled for COUP-TFI than for COUP-TFII. A fifth of COUP-TFI cells also co-expressed COUP-TFII, and cells expressing either transcription factor followed posterior or anterio-lateral pathways into the cortex, therefore, a segregation of migration pathways according to COUP-TF expression as proposed in mouse was not observed. In cultures differentiated from isolated human cortical progenitors, many cells expressed either COUP-TF and 30% also co-expressed GABA, however no cells expressed NKX2.1. This suggests interneurons could be generated intracortically from progenitors expressing either COUP-TF.

Mechanistic study of angiogenesis induced by <i>shh</i>-transfected BMMSC transplantation after myocardial infarction

Objective: To investigate the changes and mechanism of angiogenesis in myocardium induced by transplantation of the sonic hedgehog (shh) gene transfected in bone marrow mesenchymal stem cells (BMMSC) after myocardial infarction. Methods: A rat model of acute myocardial infarction was made by coronary artery ligation. The rats were randomly divided into five groups of 40 rats each. These were further subdivided into groups of 10 rats. The peripheral regions of the infarcts were injected with either BMMSCSHH (transfection group), equivalent BMMSC (cell only group), BMMSC and pcDNA3.1-Shh DNA mixture (mixture group), pcDNA3.1-shh DNA alone (gene only group), or equal volumes of low-sugar DMEM medium (control group). One, two, four, and eight weeks after transplantation, specimens were harvested from the transplantation site to determine the expression of SHH signaling pathway downstream genes Ptc1, Gli-2, COUP-TF II, angiogenesis promoting factor VEGF, and Ang-1 using RT-PCR. Results: Seven days after transplantation, the expression of SHH signaling pathway downstream genes, Ptc1, Gli-2, and COUP-TF II was significantly more pronounced in the transfection group than in the control group, cell only group, gene only group, or mixture group (Ptc1: P P P P COUP-TF II: P P P P Gli-2: P P P P Vegf and Ang-1 was significantly more pronounced than in the control group, cell only group, or gene only group (Vegf: P P P Ang-1: P P P shh-gene-transfected BMMSCs to the peripheral regions of myocardial infarcts promoted angiogenesis by upregulating downstream gene expression.

Modulation of COUP-TF expression in a cnidarian by ectopic Wnt signalling and allorecognition.

BackgroundCOUP transcription factors are required for the regulation of gene expression underlying development, differentiation, and homeostasis. They have an evolutionarily conserved function, being a known marker for neurogenesis from cnidarians to vertebrates. A homologue of this gene was shown previously to be a neuronal and nematocyte differentiation marker in Hydra. However, COUP-TFs had not previously been studied in a colonial cnidarian.Methodology/Principal FindingsWe cloned a COUP-TF homologue from the colonial marine cnidarian Hydractinia echinata. Expression of the gene was analysed during normal development, allorecognition events and ectopic Wnt activation, using in situ hybridisation and quantitative PCR. During normal Hydractinia development, the gene was first expressed in post-gastrula stages. It was undetectable in larvae, and its mRNA was present again in putative differentiating neurons and nematocytes in post-metamorphic stages. Global activation of canonical Wnt signalling in adult animals resulted in the upregulation of COUP-TF. We also monitored a strong COUP-TF upregulation in stolons undergoing allogeneic interactions. COUP-TF mRNA was most concentrated in the tissues that contacted allogeneic, non-self tissues, and decreased in a gradient away from the contact area. Interestingly, the gene was transiently upregulated during initial contact of self stolons, but dissipated rapidly following self recognition, while in non-self contacts high expression levels were maintained.Conclusions/SignificanceWe conclude that COUP-TF is likely involved in neuronal/nematocyte differentiation in a variety of contexts. This has now been shown to include allorecognition, where COUP-TF is thought to have been co-opted to mediate allorejection by recruiting stinging cells that are the effectors of cytotoxic rejection of allogeneic tissue. Our findings that Wnt activation upregulates COUP-TF expression suggests that Wnts' role in neuronal differentiation could be mediated through COUP-TF.

The orphan nuclear receptors COUP-TFI and COUP-TFII regulate expression of the gonadotropin LHβ gene

Normal sexual development and reproductive function depend on precise temporal and quantitative expression of the pituitary gonadotropins, LH and FSH. LHβ-subunit gene expression is achieved by transcription factors acting at highly conserved and closely spaced cis-elements in the proximal 200 base pairs of the promoter. We now demonstrate that LHβ promoter activity is further regulated by the orphan nuclear receptors, chicken ovalbumin upstream promoter-transcription factors (COUP-TFI and COUP-TFII). These data establish that COUP-TFs are expressed in primary pituitary gonadotropes and two gonadotrope-derived cell lines. COUP-TFs bind to two promoter regions in the LHβ gene which overlap but are distinct from two previously defined cis-elements for another orphan nuclear receptor, steroidogenic factor-1 (SF-1). Transient transfection studies demonstrated that COUP-TFs stimulate LHβ gene promoter activity in the absence of SF-1, but blunt SF-1-mediated stimulation of gene expression in a reporter construct containing both SF-1 cis-elements (GSEs). Evaluation of constructs containing mutations or truncations in the GSEs revealed a complex pattern of activation and inhibition by COUP-TF on this promoter, suggesting multiple mechanisms by which this factor modulates LHβ gene expression. To our knowledge, these data are the first to demonstrate COUP-TF expression and function in pituitary gonadotropes.

Abstract B18: Expression of CTIP2/Bcl11b is linked to disease progression in head and neck cancer and is a critical mediator of epithelial cell migration and motility during wound healing processes

Abstract We have previously shown that transcriptional regulator Ctip2 controls epidermal homeostasis during skin morphogenesis and plays a crucial role in epidermal permeability barrier (EPB) formation (1,2). In a recent study we have shown that CTIP2 expression is upregulated in human head and neck tumors and in atopic dermatitis (3,4). It is known that “cancers are wounds that do not heal” and genes implicated in wound healing are known to influence cancer progression. Interestingly, Ctip2 expression was also induced in mouse skin following tape stripping (mild injury by abrasion) and in cutaneous full thickness wounds. We therefore investigated function of Ctip2 during cutaneous wound healing using both in vitro scratch assay and in vivo full thickness wound healing assay. In the present study we looked at the Ctip2 expression levels by immunohistochemical (IHC) and western blot on wild-type mice skin after inducing mild abrasion injury by tape stripping and in full thickness wounds by punch biopsy. We have also analyzed the effect of Ctip2 deletion in the epidermis of mice skin using Ctip2ep-/- mice in these two processes using histology, immunohistochemistry (IHC), and Western blotting. Our data on in vitro scratch migration assay demonstrated a delay in keratinocyte migration and wound closure in mutant keratinocytes. Similarly, healing of cutaneous wounds was significantly delayed by 2-3 days in Ctip2ep-/- mice (selectively lacking the gene for Ctip2 in epidermal keratinocytes) in comparison to wild-type control (Ctip2L2/L2) mice where wounds closed much faster. Histological analyses of skin wounds revealed that the distance between the two migratory tongues of epithelial cells was larger in the mutant mice [1.2 fold (p<0.001)] compared to the wild-type controls (Ctip2L2/L2) suggesting a possible role of Ctip2 in re-epithelialization process probably effecting the keratinocyte migration similar to what was seen in our in vitro data on scratch migration assay. Immunohistochemistry (IHC) and western blotting confirmed a persistant expression of PCNA and the delayed induction of both K16 and K6 (markers of activated keratinocytes) in the epidermal keratinocytes from the mutant wounds compared to control mice wounds suggesting a possible delay in the onset of restoration of differentiation in the newly formed epidermis of Ctip2ep-/- mutant mice. Altogether, we showed for the first time that keratinocytic Ctip2 modulated cutaneous wound healing by affecting the re- epithelialization and differentiation processes. Identification of genes regulated by Ctip2 during wound healing which are also involved in epithelial cancer progression is expected to improve diagnosis and treatment of human epithelial cancers.

P450Arom induction in isolated control endometrial cells by peritoneal fluid from women with endometriosis

To study the effect of peritoneal fluid from women with (PF-E) and without (PF-C) endometriosis on P(450)Arom expression in endometrial cells. Experimental study. University research unit. Forty women of reproductive age with (n = 22) or without (control; n = 18) endometriosis. Peritoneal fluid and eutopic endometrial samples were obtained during surgery from women with (n = 13 and 9, respectively) and without (n = 4 and 14, respectively) endometriosis. Expression study for P(450)Arom, steroid factor 1 (SF-1), chicken ovalbumin upstream transcription factor I (COUP-TFI), and COUP-TFII messenger RNA (reverse transcriptase-polymerase chain reacion) and/or protein (immunoblot) in isolated endometrial epithelial cells transfected or not with expression vector containing SF-1, COUP-TFI, or COUP-TFII complementary DNAs. Basal messenger RNA and/or protein expression of P(450)Arom and SF-1 were augmented in endometriosis, and that of COUP-TF was diminished. In control cells, (Bu)(2)cAMP and PF-E increased P(450)Arom and SF-1 expression (but not COUP-TF expression) in a dose-dependent way, an effect not observed with PF-C, adsorbed PF-E, or 10(-5) M indomethacin. Transfected cells confirmed these results. Any treatments modified the studied molecules in endometriosis cells. These data indicate that molecules contained in PF-E favor an estrogenic microenvironment, suggesting a role in the etiopathogenesis of endometriosis enabling the survival, maintenance, and growth of endometrial implants in the ectopic locations.

Nuclear Receptors and Co-Regulators in Adrenal Tumors

We have reported that excessive steroid hormone production in adrenal cortical tumors results from the disordered expression and activity of specific steroidogenic enzymes. Since no genetic mutations in these steroidogenic enzymes have as yet been identified, disordered expression at the transcription level may be crucial for excessive hormone production in adrenocortical tumors. Nuclear receptors SF-1 and COUP-TF/DAX-1 have been shown to activate and repress, respectively, the transcription of CYP17 gene in a mutually exclusive manner in Y-1 cells. Interestingly, the expression of COUP-TF and DAX-1 is significantly decreased in the cortisol-producing adenomas, in which CYP17 is overexpressed. Conversely, DAX-1 is highly expressed in deoxycorticosterone-producing adenomas, where CYP17 expression is almost absent. These expression profiles indicate the possibility that COUP-TF and DAX-1 play important roles in the transcriptional repression of CYP17 in adrenal tumors. To clarify the mechanisms of COUP-TF-mediated repression, we therefore screened for COUP-TF-interacting proteins using a yeast two-hybrid system from a cortisol-producing adenoma cDNA library. We then cloned a novel COUP-TF-interacting protein-1 (CIP-1), which interacts with COUP-TFI, COUP-TFII, and SF-1. Functionally, CIP-1 can act as a transcriptional co-repressor for COUP-TF repression activity. CIP-1 expression profiles parallel those of COUP-TFI in steroidogenic tissues, strongly suggesting that, together, COUP-TFI and CIP-1 play an important role in steroidogenesis.

Regulation of laminin and COUP-TF expression in extraembryonic endodermal cells.

Laminin expression and the subsequent deposition of a basement membrane by primitive endoderm cells is necessary for early mammalian development. We demonstrate that the transcription factors COUP-TF I and II are up-regulated in primitive endoderm cells faster than LAMB1 and LAMC1, and that either COUP-TF is sufficient to induce expression of these laminin genes.

Orphan receptor COUP-TF is required for induction of retinoic acid receptor beta, growth inhibition, and apoptosis by retinoic acid in cancer cells.

Retinoic acid receptor beta (RARbeta) plays a critical role in mediating the anticancer effects of retinoids. Expression of RARbeta is highly induced by retinoic acid (RA) through a RA response element (betaRARE) that is activated by heterodimers of RARs and retinoid X receptors (RXRs). However, RARbeta induction is often lost in cancer cells despite expression of RARs and RXRs. In this study, we provide evidence that orphan receptor COUP-TF is required for induction of RARbeta expression, growth inhibition, and apoptosis by RA in cancer cells. Expression of COUP-TF correlates with RARbeta induction in a variety of cancer cell lines. In addition, stable expression of COUP-TF in COUP-TF-negative cancer cells restores induction of RARbeta expression, growth inhibition, and apoptosis by RA, whereas inhibition of COUP-TF by expression of COUP-TF antisense RNA represses the RA effects. In a transient transfection assay, COUP-TF strongly induced transcriptional activity of the RARbeta promoter in a RA- and RARalpha-dependent manner. By mutation analysis, we demonstrate that the effect of COUP-TF requires its binding to a DR-8 element present in the RARbeta promoter. The binding of COUP-TF to the DR-8 element synergistically increases the RA-dependent RARalpha transactivation function by enhancing the interaction of RARalpha with its coactivator CREB binding protein. These results demonstrate that COUP-TF, by serving as an accessory protein for RARalpha to induce RARbeta expression, plays a critical role in regulating the anticancer activities of retinoids.

Restoring Retinoid Signals in Cancer Cells

STKE Retinoids have multiple biological effects, including inhibition of proliferation of certain cancer cells. The retinoids often act through heterodimers of two nuclear receptors, the retinoic acid receptors (RARs) and the retinoid X receptors (RXRs). In normal cells, the expression of RARb is enhanced through transcriptional activation in response to retinoids, but many cancer cell lines lose their ability to response even though the RAR and RXR proteins are still expressed. Lin et al. now show that such retinoid-insensitive cells may be missing another nuclear receptor, the orphan receptor COUP-TF. In cancer cell lines lacking COUP-TF, expression of COUP-TF restored retinoid-induced expression of RARb as well as the apoptotic and growth inhibitory effects of retinoic acid in these cells. COUP-TF appears to enhance the interaction of RAR with the transcriptional coactivator CBP through DNA binding. This mechanism of action of COUP-TF is distinct from its effects on other genes, where it has its own transactivation activity through recruitment of a different coactivator.— LBR Mol. Cell. Biol. 20 , 957 (2000).

Orphan Nuclear Receptor Promotes Retinoid Signals

Retinoids have multiple biological effects, including inhibition of proliferation of certain cancer cells. The retinoids often act through heterodimers of two nuclear receptors, retinoic acid receptors (RARs) and the retinoid X receptors (RXRs). Normally, the expression of RARβ is enhanced through transcriptional activation in response to retinoids. However, many cancer cell lines lose this response to retinoids, even though the RAR and RXR proteins are expressed. Lin et al. now show that such retinoid-insensitive cells may be missing another nuclear receptor, the orphan receptor called COUP-TF. In cancer cell lines lacking COUP-TF, retinoid-induced expression of RARβ could be restored by expression of COUP-TF. This also restored growth inhibitory and apoptotic effects of retinoic acid in these cells. COUP-TF appears to act by enhancing interaction of RARα with the transcriptional coactivator CBP, and this effect appeared to require DNA binding by COUP-TF. This mechanism of action of COUP-TF is distinct from its effects on other genes, where COUP-TF's DNA-binding activity is not required and where it has its own transactivation activity through recruitment of a different coactivator. Lin B, Chen G.-q., Xiao D., Kolluri S.K., Cao X., Su H., Zhang X.-k. (2000) Orphan receptor COUP-TF is required for induction of retinoic acid receptor beta, growth inhibition, and apoptosis by retinoic acid in cancer cells. Mol. Cell. Biol. 20 : 957-970. [Abstract] [Full Text]

Expression of Three Negative Regulators of CYP17 Gene Transcription in Adrenocortical Cells

The expression of negative regulators of CYP17 gene expression: DAX-1, COUP-TF and N-CoR was investigated in bovine adrenocortical cells in primary culture. The cells were incubated for 6 hours in a defined medium, containing ACTH (10 nM) or forskolin (25 μM). Total RNA was isolated, the concentration of CYP17 gene transcript was determined by hybridization analysis, and polyA RNA was reverse-transcribed to obtain cDNA. Fragments of CYP17, DAX-1, COUP-TF, N-CoR and β-actin cDNA were amplified by PCR and the amplified cDNAs were analyzed by agarose gel electrophoresis followed by densitometry.It was found that DAX-1 and COUP-TF mRNA levels were unaffected by treatment with ACTH or forskolin. On the contrary, both compounds enhanced the level of mRNA encoding N-CoR. Under the same conditions, ACTH or forskolin substantially stimulated CYP17 mRNA accumulation.Our results suggest that in the adrenocortical cells in culture, the expression of DAX1 and COUP-TF is constitutive, whereas N-CoR expression might be inducible.

Orphan Receptors Coup-TF and Dax-1 as Targets in Disordered CYP17 Expression in Adrenocortical Tumors

CYP17 gene transcription is activated by SF-1 binding to a cyclic AMP-responsive sequence within the promoter region of the gene, and its transcription is inhibited by COUP-TF binding to the sequence. Another orphan receptor, DAX-1, is shown to act as a suppressor of SF-1-mediated transcription. We examined the expression level of these orphan receptors in adrenocortical tumors and compared the results with CYP17 expression. CYP17 was highly expressed in cortisol-producing adenomas, whereas COUP-TF and DAX-1 expression levels were very low. In deoxycorticosterone-producing adenomas, on the other hand, CYP17 expression was extremely low, whereas DAX-1 was highly expressed and SF-1 expression was slightly decreased. In conclusion, the reciprocal expression of CYP17 and the transcriptional repressors COUP-TF and DAX-1 indicates that these orphan receptors have a pathophysiologic role in the excessive hormone production in cortisol- and deoxycorticosterone-producing adrenocortical tumors.

Modulation of retinoic acid sensitivity in lung cancer cells through dynamic balance of orphan receptors nur77 and COUP-TF and their heterodimerization.

The diverse function of retinoic acid (RA) is mediated by its nuclear receptors, the retinoic acid receptors (RARs) and retinoid X receptors (RXRs). However, the RA response is often lost in cancer cells that express the receptors. Previously, it was demonstrated that the RA response is regulated by the COUP-TF orphan receptors. Here, we present evidence that nur77, another orphan receptor whose expression is highly induced by phorbol esters and growth factors, is involved in modulation of the RA response. Expression of nur77 enhances ligand-independent transactivation of RA response elements (RAREs) and desensitizes their RA responsiveness. Conversely, expression of COUP-TF sensitizes RA responsiveness of RAREs by repressing their basal transactivation activity. Unlike the effect of COUP-TFs, the function of nur77 does not require direct binding of nur77 to the RAREs, but is through interaction between nur77 and COUP-TFs. The interaction occurs in solution and results in inhibition of COUP-TF RARE binding and transcriptional activity. Unlike other nuclear receptors, a large portion of the carboxy-terminal end of nur77 is not required for its interaction with COUP-TF. In human lung cancer cell lines, COUP-TF is highly expressed in RA-sensitive cell lines while nur77 expression is associated with RA resistance. Stable expression of COUP-TF in nur77-positive, RA-resistant lung cancer cells enhances the inducibility of RARbeta gene expression and growth inhibition by RA. These observations demonstrate that a dynamic equilibrium between orphan receptors nur77 and COUP-TF, through their heterodimerization that regulates COUP-TF RARE binding, is critical for RA responsiveness of human lung cancer cells.

Chicken ovalbumin upstream promoter-transcription factors and their regulation

COUP-TFs are orphan members of the steroid/thyroid hormone receptor superfamily. COUP-TF homologues have been cloned in several species, from Drosophila to man. The vertebrate COUP-TFs can be classified into four subgroups according to sequence homology in their ligand-binding domain. COUP-TFs bind to AGGTCA direct repeats or palindromes with various spacings. These include the response elements of several other members of the superfamily, the vitamin D receptor, the thyroid hormone receptor, the retinoic acid receptor, the retinoid X receptor, the peroxisome proliferation activated regulator, and the hepatocyte nuclear factor-4. COUP-TF response elements have been identified in the promoters of many genes and COUP-TFs have been shown to act as negative regulators both in vitro and in vivo. They can compete with the above mentioned receptors for binding to the common response elements. The ratio of COUP-TF and the other positive regulator determines the transcriptional state of a particular gene in any given moment. COUP-TFs are expressed in the developing central nervous system of mouse and zebra fish. In addition, they are also expressed in many organs during mouse organogenesis. The expression pattern and profile of COUP-TFs favor the hypothesis that they are involved in development and differentiation. The expression of COUP-TFs are also highly regulated. P19 embryonal carcinoma cells have been used as a model system to study COUP-TF regulation. COUP-TFs are up-regulated in retinoic acid (RA) treated P19 cells. Transient transfection assay showed that mouse COUP-TFII promoter directly responded to RA treatment, suggesting that COUP-TF expression is directly regulated by RA signaling pathway.

Localization of transcripts of the related nuclear orphan receptors COUP-TF I and ARP-1 in the adult mouse brain.

The chicken ovalbumin upstream promoter transcription factor, COUP-TF I, and the protein ARP-1 (COUP-TF II) are two highly homologous orphan receptors of the nuclear hormone receptor family. In this study we investigated their expression patterns in the adult nervous system of the mouse. In situ hybridizations were performed on brain sections with 35S-labeled cRNA probes derived from the 3'-non-coding regions of the mARP-1 and mCOUP-TF I mRNAs. Both COUP-TF I and ARP-1 were shown to be expressed in the adult brain and they displayed restricted and distinct expression patterns. COUP-TF I transcripts were predominantly found in the rostral and caudal parts of the adult mouse brain, whereas ARP-1 transcripts prevaled in the middle part of the brain. High expression of COUP-TF I was detected in the olfactory nucleus, in neocortex layers I/II and V/VL, in the dentate gyrus and in areas CA1/CA3/CA4 of the hippocampus, and in the granular layer of the cerebellum. Only low amounts of COUP-TF I mRNA were detected in the ventral, the laterodorsal and in the interanteromedial thalamic nuclei. Small amounts of COUP-TF I transcripts were also found in the epithelial layer of the ventricle and in arachnoid membranes. High expression of ARP-I was detected in the reticular, the ventral lateral and the gelatinosus thalamic nuclei. Other hot spots of ARP-1 mRNA expression were the amygdaloid nucleus and the arachnoid membranes. Lower amounts of ARP-1 transcripts were found in the anterior and lateral hypothalamic areas, in the suprachiasmatic nucleus, and in the choroid plexus.(ABSTRACT TRUNCATED AT 250 WORDS)

Identification of a regulatory function for an orphan receptor in muscle: COUP-TF II affects the expression of the myoD gene family during myogenesis.

COUP-TF II is an 'orphan steroid receptor' that binds a wide variety of AGGTCA repeats and represses thyroid hormone (T3) and retinoid dependent trans-activation; however, very little is known of its functional and/or developmental role during mammalian cell differentiation. T3 and retinoids have been demonstrated to promote terminal muscle differentiation via activation of the muscle specific myoD gene family (myoD, myogenin, myf-5 and MRF-4). The myoD gene family can direct the fate of mesodermal cell lineages, repress proliferation, activate differentiation and the contractile phenotype. Hence, we investigated the expression and functional role of COUP-TF II during muscle differentiation. Proliferating C2C12 myoblasts expressed COUP-TF II mRNA which was repressed when cells were induced to differentiate into post-mitotic multinucleated myotubes by serum withdrawal. Concomitant with the decrease of COUP-TF II mRNA was the appearance of muscle specific mRNAs (e.g. myogenin, alpha-actin). We show that Escherichia coli expressed full length and truncated COUP-TF II bound in a sequence specific manner to the T3 response elements (TREs) in the myoD and myogenin regulatory HLH genes [Olson (1992) Dev. Biol. 154, 261-272]; and the TRE in the skeletal alpha-actin contractile protein gene. COUP-TF II diminished the homodimeric binding of the thyroid hormone receptor and the heterodimeric binding of thyroid hormone and retinoid X receptor complexes to these TREs. Constitutive over-expression of COUP-TF II cDNA in mouse C2C12 myogenic cells suppressed the levels of myoD mRNA and blocked the induction of myogenin mRNA, whereas constitutive expression of anti-sense COUP-TF II cDNA significantly increased the steady state levels of myoD mRNA and hyper-induced myogenin mRNA. These studies demonstrate for the first time (i) that COUP-TF II, functions as a physiologically relevant antagonistic regulator of myogenesis via direct effects on the myoD gene family and (ii) direct evidence for the developmental role of COUP-TF II during mammalian cell differentiation.

An evolutionary conserved COUP-TF binding element in a neural-specific gene and COUP-TF expression patterns support a major role for COUP-TF in neural development

An evolutionary conserved COUP-TF binding element in a neural-specific gene and COUP-TF expression patterns support a major role for COUP-TF in neural development