Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.27.1 (RNase)
 16,360 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We report here the cDNA cloning and characterization of a rat basic helix-loop-helix (HLH) factor, designated HES-5. This factor has a distant sequence homology to Drosophila hairy and Enhancer-of-split proteins, both of which are required for normal neurogenesis. DNase I footprinting analyses show that HES-5 binds to the sequence CACNAG (called N box), a recognition sequence of Enhancer-of-split proteins. Although HES-5 does not bind to the sequence CANNTG (called E box) recognized by other HLH factors, it attenuates the binding of E47, an HLH activator, to E box by forming a hetero-oligomer. In cotransfection analyses using NIH 3T3 cells, HES-5 significantly represses transcription originating from the promoter containing the N box sequences. Furthermore, HES-5 also partially inhibits the E47-induced expression from the promoter containing E boxes. Northern blot, RNase protection, and in situ hybridization analyses demonstrate that the HES-5 mRNA is specifically expressed in the nervous system. Prominent expression is observed in the ventricular zones of the embryonal brain vesicles and the outer nuclear layer of the neural retina. These results suggest that the negative regulator HES-5 may play an important role in neural development.
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PMID:Molecular characterization of a rat negative regulator with a basic helix-loop-helix structure predominantly expressed in the developing nervous system. 140 Apr 97

Previous work has identified multiple human AMPD3 transcripts proposed to differ by mutually exclusive alternative splicing of three exons located at, or near, the 5' end of the gene. In this study, we perform a more comprehensive evaluation of human AMPD3 gene expression. Combined Northern blot and RNase protection analyses show that alternative mRNAs are widely expressed in human tissues and cells, but at variable relative abundances. Sequencing of human genomic clones, together with human-mouse somatic cell hybrid analysis, demonstrates that the entire gene is comprised of seventeen exons spanning approx. 60 kilobases on the short arm of chromosome 11 in the region p13-pter. Together, RT-PCR and additional RNase protection analyses establish that exons 1a, 1b, and 1c are 5' terminal sequences in alternative transcripts. Transient transfection experiments show fusion constructs containing proximal flanking and 5' untranslated sequence from each of these exons are able to direct expression of a reporter luciferase gene in mammalian cell lines. These combined results reveal that AMPD3 gene expression is subject to transcriptional control by three tandem promoters. Differential regulation of the exon 1b promoter in skeletal myocytes, as compared to retinal pigment epithelial cells, is proposed to be mediated by skeletal muscle-specific basic helix-loop-helix protein/E-box interactions. Finally, an internal splice acceptor site in exon 1c is shown to be used alternatively to retain the 3' portion of this exon in mature AMPD3 transcripts initiating upstream in exon 1b.
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PMID:Characterization of the human AMPD3 gene reveals that 5' exon useage is subject to transcriptional control by three tandem promoters and alternative splicing. 861 27

The environmental contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin induces the microsomal enzyme cytochrome P4501A1 by increasing the transcription rate of the CYP1A1 gene. Induction requires two basic helix-loop-helix proteins, the ligand-binding aromatic hydrocarbon receptor (AhR) and its heterodimerization partner, the AhR nuclear translocator (Arnt). The AhR/Arnt heterodimer induces transcription by binding to dioxin-responsive elements (DREs) within an enhancer upstream of the CYP1A1 gene. The basic regions of AhR and Arnt are crucial for DRE binding. We have mutated these regions in order to analyze the relationship between DRE binding (determined in vitro using an electrophoretic mobility shift assay) and induction of CYP1A1 transcription (determined in vivo by genetic complementation of AhR-defective and Arnt-defective mouse hepatoma cells, using an RNase protection assay to measure mRNA accumulation). Our findings reveal the amino acids in the basic regions of AhR/Arnt that are important for both DRE binding and induction of transcription. This information provides biological background for the interpretation of structural (e.g. crystallographic) studies of the interactions between AhR/Arnt and the DRE. Our findings also indicate that the in vitro behavior of the mutants does not consistently predict their functional activity in vivo. Thus, genetic complementation constitutes an important and stringent test for analyzing the effects of mutations on AhR/Arnt function.
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PMID:DNA binding by the heterodimeric Ah receptor. Relationship to dioxin-induced CYP1A1 transcription in vivo. 862 73

bHLH-EC2 is a recently characterized member of a growing family of basic helix-loop-helix transcription factors. This family includes bHLH factors such as twist, which appear to be primarily involved in early mesodermal differentiation, and bHLH factors such as TAL-1, which have been characterized through their association with chromosomal breakpoints associated with T-cell leukemias. To provide for studies aimed at understanding the genetic regulation of bHLH-EC2, we have characterized the organization of this gene and conducted preliminary studies of the transcriptional activity of the upstream promoter region. The mouse bHLH-EC2 gene was found to consist of two exons separated by a 5-kb intron, an organization pattern similar to the mouse twist gene. The transcription initiation site was identified by RNase protection assay and primer extension analysis. Linked promoter-reporter gene transfection experiments in cultured cells indicated that while the identified upstream sequence can function to promote transcription, it does not function in a cell-specific fashion. To investigate the possible association of bHLH-EC2 with hematological malignancy, the chromosomal location of this gene in the human was mapped by fluorescence in situ hybridization and assigned to chromosome band 20p13.
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PMID:Genomic organization and chromosomal localization of the gene TCF15 encoding the early mesodermal basic helix-loop-helix factor bHLH-EC2. 882 48

We have isolated cDNAs representing multiple members of murine groucho homologues, designated Grg for groucho-related genes. Among them, Grg3 appears to produce two transcripts. One of the Grg3 transcripts contains coding sequence for a complete Groucho protein homologue. The second transcript contains coding sequence for only the two amino-terminal domains of the Groucho protein, followed by a hydrophobic tail and a stop codon. We analyzed the expression of both transcripts in mouse embryos using RNase protection and in situ hybridization. Expression was detected during cell determination in the nervous system and in somitic mesoderm, overlapping Notch1 expression and adjacent to Mash1, MyoD and Myf5 expression. Thus, the expression pattern of Grg3 suggests a conserved role in the Notch signalling pathway to regulate expression of basic helix-loop-helix proteins and cell determination. Grg3 expression was also consistently detected in epithelial structures undergoing mesenchyme induction.
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PMID:Grg3, a murine Groucho-related gene, is expressed in the developing nervous system and in mesenchyme-induced epithelial structures. 898 17

The basic helix-loop-helix (bHLH) class of proteins are of major importance in controlling tissue-specific gene expression. The actions of the bHLH proteins are inhibited by a related class of proteins, inhibitors of differentiation (Id). We have studied the expression of one of these latter proteins, Id-1, in the normal and post-ischemic regenerating rat kidney by immunocytochemistry, Western blot and RNase protection assay (RPA) and correlated Id-1 regulation to the expression of vimentin and proliferating cellular nuclear antigen (PCNA). In the normal kidney strong immunostaining for Id-1 was found in the distal nephron, especially in the distal convoluted tubule in the cortex. In particular, the perinuclear region was intensely stained in the cells of the distal tubule. mRNA for Id-1I was detectable by RPA on total RNA extracted from the renal cortex of sham-operated animals. The Id-1 monomer was detected on Western blots of normal animals. Vimentin was expressed in the mesangial cells of the glomeruli and in cells in the interstitium while tubule cells were negative. The labeling intensity for PCNA was low in all cellular compartments in the normal kidney. In the regenerating kidneys at various time intervals, the expression of Id-1-like immunoreactivity was widespread in the regenerating dedifferentiated tubule cells while by the end of the study period, more highly differentiated tubule cells appeared to lose their staining. On Western blots the Id-1 monomer was undetectable and instead strong staining was seen in the high molecular range. Id-1 mRNA levels in the regenerating kidneys did not differ significantly when compared to sham. PCNA labeling was intense in the regenerating kidneys at all time periods studied, indicating the intense proliferative activity in the regenerating kidneys. Vimentin expression in the renal tubule cells was increased from day 3 and onward. The data are consistent with a hypothesis in which Id-1 regulates differentiation of renal tubule cells in the post-ischemic regenerating rat kidney.
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PMID:Expression of Id-1 mRNA and protein in the post-ischemic regenerating rat kidney. 963 41

Kidney-specific cadherin (Ksp-cadherin, cadherin 16) is a novel, kidney-specific member of the cadherin superfamily that is expressed exclusively in the basolateral membrane of renal tubular epithelial cells. To characterize the Ksp-cadherin gene promoter, a lambda bacteriophage clone containing 3.7 kb of the proximal 5' flanking region of the mouse Ksp-cadherin gene was isolated. The transcription initiation site was mapped by RNase protection assays and 5' rapid amplification of cDNA ends, and a 709-bp intron was identified within the 5' untranslated region. The proximal 5' flanking region was "TATA-less" but contained other consensus promoter elements including an initiator (Inr), GC boxes, and a CAAT box. Potential binding sites were identified for transcription factors that are involved in tissue-specific gene expression including activator protein-2 (AP-2), hepatocyte nuclear factor-3 (HNF-3), basic helix-loop-helix (bHLH) proteins, CCAAT/enhancer-binding protein (C/EBP), and GATA factors. Transfection of luciferase reporter plasmids containing 2.6 kb of the 5' flanking region markedly increased luciferase activity in renal epithelial cells (MDCK and mIMCD-3) but not in mesenchymal cells (NIH 3T3 and MMR1). Deletion analysis identified an 82-bp region from -31 to -113 that was essential for promoter activity in transfected renal epithelial cells. Electrophoretic mobility-shift assays showed that mIMCD-3 cells contain nuclear proteins that bind to this region of the promoter. Mutational analysis showed that sequences within the HNF-3 consensus site and CAAT box were involved in protein binding and promoter activity. We conclude that the proximal 5' flanking region of the mouse Ksp-cadherin gene contains an orientation-dependent promoter that is kidney epithelial cell specific. The region of the promoter from -113 to -31 is required for transcriptional activity and contains binding sites for nuclear proteins that are specifically expressed in renal epithelial cells.
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PMID:Ksp-cadherin gene promoter. I. Characterization and renal epithelial cell-specific activity. 1051 84

Transcription factors of the basic helix-loop-helix family such as Mash2 are essential for adequate differentiation of the trophoblast. Disruption of the Mash2 gene leads to early intrauterine death caused by placental insufficiency with an absent spongiotrophoblast and an underdeveloped chorion. The aim of the present study was to analyze the structure of the murine Mash2 gene, to screen a broad spectrum of organs for its expression, and to investigate placental Mash2 expression at different gestational ages. The RNase protection assay identified, in addition to the postulated Mash2 mRNA, two unexpected Mash2 transcripts that could be confirmed by a 5' rapid amplification of cDNA ends. However, all three transcripts were detectable exclusively in murine placenta and not in other organs, such as the ovary, uterus, skin, lung, femur, skeletal muscle, kidney, skull, adrenal gland, tongue, stomach, spleen, skin, testis, or pancreas. Sequence analysis disclosed an additional transcription start site upstream of exon 2. Placental Mash2 mRNA is measurable at all investigated stages of gestation. After its initial detection on Day 8.5 postcoitum (p.c.; set to 100%; 100.0% +/- 28.4%), the Mash2 mRNA concentration increases significantly and reaches a maximum of 812.0% +/- 69.7% on Day 12.5 p.c. The second half of gestation is marked by a more than 8-fold Mash2 decrease by Day 18.5 p.c. (77.0% +/- 28.4%). A 36.9% +/- 4.7% level of placental Mash2 mRNA is measurable at term.
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PMID:Structure and regulation of the murine Mash2 gene. 1249 93

Hairy-related transcription factor (HRT/Hey) genes encode a novel subfamily of basic helix-loop-helix (bHLH) transcription factors related to the Drosophila hairy and Enhancer-of-split (E(spl)) and the mammalian HES proteins that function as downstream mediators of Notch signaling. Using the yeast two-hybrid approach, a previously uncharacterized protein was identified in Xenopus that interacts with XHRT1 (originally referred to as bc8), one member of the HRT/Hey subclass. This protein is evolutionarily conserved in chordates. It binds to sequences adjacent to the bHLH domain of XHRT1 known as the Orange domain and has been named bc8 Orange interacting protein (BOIP). BOIP shows a rather uniform subcellular localization and is recruited to the nucleus upon binding to XHRT1. In Xenopus, XBOIP mRNA is detected by RNase protection analysis throughout embryogenesis. In the adult, the strongest expression is detected in testis. In the mouse, high levels of BOIP mRNA are also found in adult testis. No expression is detected in the embryo and in any of the other adult organs tested. In situ hybridization revealed that BOIP transcripts were detected almost exclusively in round spermatids and that this expression overlaps with that of Hey1 (HRT1), which is expressed throughout spermatogenesis. In view of the importance of the Orange domain for HRT/Hey function, the newly identified BOIP proteins may serve as regulators specifically of HRT1/Hey1 activity.
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PMID:Identification of BOIP, a novel cDNA highly expressed during spermatogenesis that encodes a protein interacting with the orange domain of the hairy-related transcription factor HRT1/Hey1 in Xenopus and mouse. 1464 48

Tissue-specific class B basic helix-loop-helix (bHLH) transcription factors, dimerising with ubiquitously produced class A bHLH proteins, play a major role in murine trophoblast development. Here, we investigated expression patterns of class A and B bHLH factors in the human placenta and different trophoblast culture systems. Semi-quantitative RT-PCR and RNase protection assay revealed expression of the tissue-restricted factors Hash-2, I-mfa and Stra13 in placentae of early and late pregnancy, in purified villous trophoblasts as well as in invasive trophoblasts isolated from first trimester villous explant cultures. Accordingly, RNA in situ hybridisation localised Hash-2, I-mfa and Stra13 to the trophoblast epithelium, cell columns and extravillous trophoblasts invading maternal decidua. Villous stromal cells in situ and cultivated placental fibroblasts also produced I-mfa and Stra13 but failed to express Hash-2. The widely expressed class A proteins, E12/E47 were absent from all placental cell types while ITF-2 was restricted to placental stromal cells of early and late gestation. In contrast, HEB was identified in all trophoblast cell types using RT-PCR, Western blotting and immunohistochemistry. The negative HLH-regulators Id-1 and Id-2 lacking the DNA-binding domain, were detected in villous stromal cells and different cytotrophoblast subtypes but were absent from the syncytium. The data suggest that a complex interplay of activators (Hash-2, HEB) and repressors (Stra13, I-mfa) could be involved in extravillous trophoblast differentiation whereas downregulation of Id proteins could play a role in syncytialisation.
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PMID:Tissue-specific and ubiquitous basic helix-loop-helix transcription factors in human placental trophoblasts. 1599 2


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