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Results for “POU Domain Factors”

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At least 307 records · Page 17Linked to original sources
PubMed1998

Development of neuroendocrine lineages requires the bHLH-PAS transcription factor SIM1.

The bHLH-PAS transcription factor SIM1 is expressed during the development of the hypothalamic-pituitary axis in three hypothalamic nuclei: the paraventricular nucleus (PVN), the anterior periventricular nucleus (aPV), and the supraoptic nucleus (SON). To investigate Sim1 function in the hypothalamus, we produced mice carrying a null allele of Sim1 by gene targeting. Homozygous mutant mice die shortly after birth. Histological analysis shows that the PVN and the SON of these mice are hypocellular. At least five distinct types of secretory neurons, identified by the expression of oxytocin, vasopressin, thyrotropin-releasing hormone, corticotropin-releasing hormone, and somatostatin, are absent in the mutant PVN, aPV, and SON. Moreover, we show that SIM1 controls the development of these secretory neurons at the final stages of their differentiation. A subset of these neuronal lineages in the PVN/SON are also missing in mice bearing a mutation in the POU transcription factor BRN2. We provide evidence that, during development of the Sim1 mutant hypothalamus, the prospective PVN/SON region fails to express Brn2. Our results strongly indicate that SIM1 functions upstream to maintain Brn2 expression, which in turn directs the terminal differentiation of specific neuroendocrine lineages within the PVN/SON.

Amino Acid Sequence↗
PubMed1999

A requirement for the POU transcription factor, Brn-2, in corticotropin-releasing hormone expression in a neuronal cell line.

The expression of the endogenous CRF gene was examined in the human neuroblastoma cell line, BE(2)-M17. In this cell line, treatment with retinoic acid induces CRF mRNA transcription. We examined the requirement for the POU transcription factor, Bm-2, for this response. We confirmed that Bm-2 is expressed in retinoic acid-induced BE(2)-M17 cells. Expression of antisense Bm-2 message aborted the retinoic acid-mediated induction of CRF transcription. However, overexpression of Bm-2 was not sufficient for CRF expression in the absence of retinoic acid. These experiments support the hypothesis that Bm-2 is an intermediary for retinoic acid-induced CRF expression.

Binding Sites↗
PubMed2006

Regulation of RNA-polymerase-II-dependent transcription by N-WASP and its nuclear-binding partners.

The presence of actin in the nucleus has been well established, and several studies have implicated nuclear actin in transcriptional regulation. Neuronal Wiskott-Aldrich syndrome protein (N-WASP) is a member of the WASP family of proteins; these proteins function in the cytoplasm as key regulators of cortical actin filament. Interestingly, N-WASP has also been observed in the nucleus. However, a potential nuclear function for N-WASP has not been established. Here, we report the identification of nuclear N-WASP within a large nuclear-protein complex containing PSF-NonO (polypyrimidine-tract-binding-protein-associated splicing factor-non-Pou-domain octamer-binding protein/p54(nrb)), nuclear actin and RNA polymerase II. The PSF-NonO complex is involved in the regulation of many cellular processes, such as transcription, RNA processing, DNA unwinding and repair. We demonstrate that the interaction of N-WASP with the PSF-NonO complex can couple N-WASP with RNA polymerase II to regulate transcription. We also provide evidence that the potential function of N-WASP in promoting polymerization of nuclear actins has an important role in this process. Based on these results, we propose a nuclear function for N-WASP in transcriptional regulation.

Actin Cytoskeleton↗
PubMed2004

Olfactory receptor neuron axon targeting: intrinsic transcriptional control and hierarchical interactions.

From insects to mammals, olfactory receptor neurons (ORNs) expressing a common olfactory receptor target their axons to specific glomeruli with high precision. Here we show in Drosophila that the POU transcription factor Acj6 controls the axon targeting specificity of a subset of ORN classes, as defined by the olfactory receptors that they express. Of these classes, some require Acj6 cell-autonomously, whereas others require Acj6 cell-nonautonomously. Mosaic analyses show that cooperative targeting occurs between axon terminals of the same ORN classes and that there are hierarchical interactions among different ORN classes. We propose that the precision of ORN axon targeting derives from both intrinsic transcriptional control and extensive axon-axon interactions.

Animals↗
PubMed1995

The brn-2 gene regulates the melanocytic phenotype and tumorigenic potential of human melanoma cells.

The Oct transcription factors N-Oct-3 and N-Oct-5 are differentially expressed in normal melanocytes, melanoma tumors and cell lines. We have cloned the human brn-2 gene and have shown that it encodes both the N-Oct-3 and N-Oct-5 octamer binding activities detected in melanoma cells. The brn-2 genomic locus has been mapped to chromosome 6q16 and although chromosomal aberrations are common in this region in melanoma, no deletion or rearrangement of the brn-2 gene in melanoma cell lines was observed. Sequencing of the entire gene showed that there are no intervening sequences within the open reading frame. Antisense RNA-mediated inhibition of brn-2 gene expression in melanoma cells was associated with a change in morphology and loss of melanocytic and neural crest markers, including the melanocyte transcription factor microphthalmia and the TYRP pigmentation genes. In addition, loss of brn-2 in these cells resulted in the complete loss of ability to form tumors in SCID and nu/nu mice. These results suggest roles for brn-2 in the determination of the melanocytic lineage and in the tumorigenic phenotype of melanoma.

Animals↗
PubMed1998

Polar amino acid-rich sequences bind to polyglutamine tracts.

Polyglutamine tracts are found in different proteins including transcription factors and cofactors as well as in triplet repeat disease gene products. To characterize the protein motif that binds to the polyglutamine tract, we screened a human embryonic brain cDNA library with the polyglutamine tract of Brn-2 as bait using the yeast two-hybrid method. All six isolated clones encoding polyglutamine tract binding proteins were rich in polar amino acids. Three of these clones could form polar helical structures. These observations suggest that polar amino acid-rich sequences are essential for binding to the polyglutamine tract.

Amino Acid Sequence↗
PubMed2000

Complex interactions between epidermal POU domain and activator protein 1 transcription factors regulate the expression of the profilaggrin gene in normal human epidermal keratinocytes.

The human profilaggrin gene is expressed in the granular layer during the late stages of the epidermal differentiation. The proximal promoter region of the gene confers high levels of keratinocyte-specific transcription via interactions with c-Jun/c-Fos heterodimers. Here we provide evidence for another level of complexity in the regulation of the profilaggrin promoter activity. The POU domain proteins Oct1, Skn1a/i, and Oct6, which are abundantly expressed in the epidermal cells, act to both stimulate and repress transcription in a general and a cell type-specific mode. While binding to specific recognition elements within the promoter region, they exert their effects by either stimulating or antagonizing the c-Jun-dependent activity of the promoter. The response of the promoter to forced expression of the POU domain proteins reflects the effect of these transcription factors on the endogenous profilaggrin mRNA synthesis and suggests that the latter requires a fine balance in the amounts and the activities of the individual activator protein 1 and POU domain proteins.

Base Sequence↗
PubMed2006

A global genomic transcriptional code associated with CNS-expressed genes.

Highly conserved non-coding DNA regions (HCNR) occur frequently in vertebrate genomes, but their functional roles remain unclear. Here, we provide evidence that a large portion of HCNRs are enriched for binding sites for Sox, POU and Homeodomain transcription factors, and such HCNRs can act as cis-regulatory regions active in neural stem cells. Strikingly, these HCNRs are linked to several hundreds of genes expressed in the developing CNS and they may exert locus-wide regulatory effects on multiple genes flanking their genomic location. Moreover, these data imply a unifying transcriptional logic for a large set of CNS-expressed genes in which Sox and POU proteins act as generic promoters of transcription while Homeodomain proteins control the spatial expression of genes through active repression.

Animals↗
PubMed1993

A CNS-specific POU transcription factor, Brn-2, is required for establishing mammalian neural cell lineages.

The pluripotent embryonal carcinoma cell line P19 can differentiate in vitro into neurons and astrocytes. By employing this neural cell differentiation system, we have studied the expression and function of a POU transcription factor implicated in mammalian neurogenesis. When P19 cells differentiated to the neural cells, one of the CNS-specific POU genes (Brn-2) was selectively induced. The induction of Brn-2 was specific to the neural cell lineages and took place at the early stage of differentiation. When the Brn-2 induction was blocked/delayed by antisense RNA, such cells were unable to differentiate to neurons and astrocytes. Instead they differentiated to nonneural cells, including smooth and skeletal muscle cells. Furthermore, with reduced levels of antisense RNA, differentiation to neural cells occurred. These results indicate that Brn-2 is essential for the neural cell differentiation of P19 cells and suggest that Brn-2 is one of the genes required for establishing neural cell lineages in mammals.

Animals↗
PubMed2002

Heterospecific transgenesis in Drosophila suggests that engrailed.a is regulated by POU proteins in the crustacean Sacculina carcini.

Almost all knowledge of the regulation of segmentation genes in arthropods comes from Drosophila. In order to study the regulation of the segment-polarity gene engrailed in a non-insect arthropod we focussed on putative regulatory regions of the engrailed.a (en.a) gene in the barnacle crustacean Sacculina carcini. In this animal, en.ais expressed in segmental stripes like the engrailed genes of other arthropods. As transgenesis in Sacculina is not possible at present, we have used Drosophila as a test tube. The Sacculina en.aintron is able to induce a specific expression of lacZin the Drosophila wing imaginal disc.This pattern is not an engrailed-like pattern, but does suggest that some Drosophila transcription factors interact with the Sacculina en.a intron. We show that two DrosophilaPOU proteins, Nubbin and VVL, and Engrailed itself bind to the Sacculina en.a intron in vitro and that they regulate this expression in vivo. The conservation of POU protein binding sites in metazoans suggests that Sacculina POU proteins could recognize the same sequences. Hence, we looked at the expression of nubbin and vvlhomologues in Sacculinalarvae. Indeed, their expression patterns are consistent with a putative regulatory function on en.a in segments and appendages. Remarkably, the vvl homologue is expressed in Sacculina in a striking striped pattern that is very different from the vvl pattern in Drosophila embryos, and is complementary to the Sacculina en.a pattern. These experiments suggest that the Sacculina engrailed.a gene is regulated by POU proteins.

Animals↗
PubMed2001

Constitutive expression of MHC class II genes in melanoma cell lines results from the transcription of class II transactivator abnormally initiated from its B cell-specific promoter.

In melanoma cell lines, two different patterns of MHC class II expression have been described, either an IFN gamma-inducible expression of HLA-DR and HLA-DP, with a faint or null expression of HLA-DQ, resembling that described for melanocytes, or a constitutive expression, i.e., IFN-gamma independent, of all three HLA-D isotypes. As this latter phenotype has been associated with a more rapid progression of melanoma tumors, we have analyzed in different melanoma cell lines the molecular mechanisms leading to this abnormal pattern of MHC class II expression. In agreement with the evidence of a coordinate transcription of the HLA-D genes in these cell lines, we have shown the constitutive expression of CIITA (class II transactivator) transcripts, CIITA being known as the master switch of MHC class II expression. Unexpectedly, these transcripts initiate from promoter III of the CIITA gene, a promoter that is mainly used constitutively in B lymphocytes. This expression was further shown to occur through factor(s) acting on the enhancer located upstream of CIITA promoter III, which was previously described in epithelioid cells as an IFN-gamma-response sequence. The hypothesis of a general abnormality of the IFN-gamma transduction pathway was dismissed. Constitutive transcription of CIITA from promoter III having been observed in unrelated melanoma cell lines, we propose the hypothesis that this phenomenon might not be a random event, but could be linked to the neoplasic state of the melanoma cells.

5' Untranslated Regions↗
PubMed1992

Human small cell lung cancer expresses the octamer DNA-binding and nervous system-specific transcription factor N-Oct 3 (brain-2).

Small cell lung cancer (SCLC) cells express several characteristics of neuronal cells, including synthesis of neuropeptides and expression of the respective receptors. Establishment and maintenance of the neuronal phenotype of SCLC may depend on expression of gene transcription factors inherent to the central nervous system. The present study shows the nervous system-specific transcription factor N-Oct 3 (brain-2) to be expressed in all 13 SCLC cell lines investigated. Furthermore, N-Oct 3 (brain-2) was also found in SCLC-derived skin metastasis. In contrast, in extracts and RNA of non-SCLC cell lines and non-SCLC tumor tissues, such as lung squamous, large cell, and adenocarcinoma, expression of N-Oct 3 (brain-2) was not detectable. These data support the concept that SCLC cells derive from the neuroectodermal cell lineage since expression of N-Oct 3 (brain-2) protein is highly abundant at the neural tube stage and in the adult restricted to the neuroectodermal cell lineage.

Carcinoma, Small Cell↗
PubMed2006

Exclusion of mutations in the PRNP, JPH3, TBP, ATN1, CREBBP, POU3F2 and FTL genes as a cause of disease in Portuguese patients with a Huntington-like phenotype.

Huntington disease (HD) is an autosomal dominant neurodegenerative disorder characterised by chorea, cognitive impairment, dementia and personality changes, caused by the expansion of a CAG repeat in the HD gene. Often, patients with a similar clinical presentation do not carry expansions of the CAG repeat in this gene [Huntington disease-like (HDL) patients]. We report the genetic analysis of 107 Portuguese patients with an HDL phenotype. The HDL genes PRNP and JPH3, encoding the prion protein and junctophilin-3, respectively, were screened for repeat expansions in these patients. Given the partial clinical overlap of SCA17, DRPLA and neuroferritinopathy with HD, their causative genes (TBP, ATN1, and FTL, respectively) were also analysed. Finally, repeat expansions in two candidate genes, CREBBP and POU3F2, which encode the nuclear transcriptional coactivator CREB-binding protein and the CNS-specific transcription factor N-Oct-3, respectively, were also studied. Expansions of the repetitive tracts of the PRNP, JPH3, TBP, ATN1, CREBBP and POU3F2 genes were excluded in all patients, as were sequence alterations in the FTL gene. Since none of the genes already included in the differential diagnosis of HD was responsible for the disease in our sample, the genetic heterogeneity of the HDL phenotype is still open for investigation.

Adolescent↗
PubMed1995

Activation of the herpes simplex virus immediate-early gene promoters by neuronally expressed POU family transcription factors.

Herpes simplex virus immediate-early (IE) promoters contain the TAATGARAT motif which acts as a target site for the cellular POU family transcription factors Oct-1 and Oct-2. Here we show that other members of the POU family that are expressed in sensory neurons can also affect IE promoter activity. In particular, two members of the Brn-3 family of POU proteins Brn-3a and Brn-3c can activate the IE-1 and IE-3 promoters when co-transfected into fibroblasts and neuronal cells whereas a third member Brn-3b represses IE promoter activity. In contrast, Brn-3 proteins cannot overcome the inhibitory effect of neuronal Oct-2 on IE promoter activity in co-transfections nor do they prevent transactivation of the IE promoters by the Oct-1-Vmw65 complex. The potential regulation of the IE promoters by several different neuronally expressed POU proteins during the initiation, maintenance and re-activation of latent infection in sensory neurons is discussed.

Animals↗
PubMed2006

Pdm and Castor specify late-born motor neuron identity in the NB7-1 lineage.

Embryonic development requires generating cell types at the right place (spatial patterning) and the right time (temporal patterning). Drosophila neuroblasts undergo stem cell-like divisions to generate an ordered sequence of neuronal progeny, making them an attractive system to study temporal patterning. Embryonic neuroblasts sequentially express Hunchback, Krüppel, Pdm1/Pdm2 (Pdm), and Castor (Cas) transcription factors. Hunchback and Krüppel specify early-born temporal identity, but the role of Pdm and Cas in specifying temporal identity has never been addressed. Here we show that Pdm and Cas regulate late-born motor neuron identity within the NB7-1 lineage: Pdm specifies fourth-born U4 motor neuron identity, while Pdm/Cas together specify fifth-born U5 motor neuron identity. We conclude that Pdm and Cas specify late-born neuronal identity; that Pdm and Cas act combinatorially to specify a temporal identity distinct from either protein alone, and that Cas repression of pdm expression regulates the generation of neuronal diversity.

Animals↗
PubMed2003

Crucial roles of Brn1 in distal tubule formation and function in mouse kidney.

This study identifies a role for the gene for the POU transcription factor Brn1 in distal tubule formation and function in the mammalian kidney. Normal development of Henle's loop (HL), the distal convoluted tubule and the macula densa was severely retarded in Brn1-deficient mice. In particular, elongation and differentiation of the developing HL was affected. In the adult kidney, Brn1 was detected only in the thick ascending limb (TAL) of HL. In addition, the expression of a number of TAL-specific genes was reduced in the Brn1+/- kidney, including Umod, Nkcc2/Slc12a1, Bsnd, Kcnj1 and Ptger3. These results suggest that Brn1 is essential for both the development and function of the nephron in the kidney.

Animals↗
PubMed1994

Promoter of the POU-M1/SGF-3 gene involved in the expression of Bombyx silk genes.

To characterize the transcription regulation of the POU-M1/SGF-3 gene, we have cloned a genomic DNA fragment encompassing the whole coding region and its flanking sequences. This gene does not contain any intron. The 5'-flanking region of the gene contains several interesting motifs, such as homeodomain-binding motifs, sequences resembling the transcriptional factor Sp1-binding site, and TGTTT motifs, but lacks some of the typical transcriptional regulatory sequences, such as TATA and CCAAT boxes. Transcriptional analysis of a series of deletion mutants of the gene in the nuclear extracts prepared from the middle silk gland of 2-day-old fifth instar larvae revealed the presence of multiple cis-regulatory elements located both upstream and downstream of the initiation site. One of these elements, the homeodomain-binding element, was identified to mediate negative regulation. By mobility shift assay using the POU-M1 specific antibodies, we found that this negative element interacts with the POU-M1/SGF-3. Transcription analysis in vitro using templates mutagenized in the PB region and one of the POU-M1 antibodies indicated that the PB region is an autoregulatory element responsible for SGF-3-dependent transcriptional repression.

Animals↗
PubMed1999

Altered cochlear fibrocytes in a mouse model of DFN3 nonsyndromic deafness.

DFN3, an X chromosome-linked nonsyndromic mixed deafness, is caused by mutations in the BRN-4 gene, which encodes a POU transcription factor. Brn-4-deficient mice were created and found to exhibit profound deafness. No gross morphological changes were observed in the conductive ossicles or cochlea, although there was a dramatic reduction in endocochlear potential. Electron microscopy revealed severe ultrastructural alterations in cochlear spiral ligament fibrocytes. The findings suggest that these fibrocytes, which are mesenchymal in origin and for which a role in potassium ion homeostasis has been postulated, may play a critical role in auditory function.

Animals↗