Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.30.1 (S1 nuclease)
 3,660 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The rate of response to thyroid hormone on cardiac growth, heart rate, and the relative changes in messenger RNA (mRNA) coding for alpha- and beta-myosin heavy chain (MHC), slow sarcoplasmic reticulum calcium-adenosine triphosphatase, and thyroid hormone receptors in ventricular tissue of hypothyroid rats was investigated. Hypothyroid rats had significantly smaller hearts, with slower heart rates and expressed no alpha-MHC mRNA as analyzed by an S1 nuclease protection assay when compared to euthyroid animals that expressed 79% alpha-MHC. Twelve hours after treating hypothyroid rats with 20 micrograms of L-T4, detectable levels of alpha-MHC mRNA were present and the shift to alpha-MHC mRNA was complete by 72 h of treatment. Northern blot analysis showed that hypothyroidism resulted in a 60% decrease in the level of sarcoplasmic reticulum calcium-adenosine triphosphatase mRNA which increased after 12 h of T4 administration and was 2.5-fold (P less than 0.05) greater than euthyroid levels after 72 h. In contrast, thyroid hormone receptor mRNA levels measured in poly(A)+ RNA were elevated in hypothyroid rats and decreased to euthyroid levels within 24 h after thyroid hormone treatment. These changes in cardiac gene expression occurred simultaneously with changes in both cardiac size and heart rate. The current studies characterize the coordinated changes and the time course for gene expression that occur in the hypothyroid heart after acute T4 administration.
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PMID:Time course of the in vivo effects of thyroid hormone on cardiac gene expression. 131 35

The promoter region of the human (h) thyroid hormone receptor (TR) beta 1 gene was isolated from a human placenta genomic library. Primer extension and S1 nuclease mapping confirmed a single transcriptional start site. DNA sequence analysis of the 5' upstream region revealed the existence of a putative thyroid response element (TRE) which is highly homologous to TREs found in several thyroid hormone responsive genes. Binding of hTR protein to the promoter region of the hTR beta 1 gene was confirmed by gel mobility shift assay. A transient transfection study demonstrated that hTR activated the expression of a reporter gene containing the promoter sequence of the hTR beta 1 gene in a hormone dependent manner. The TRE in the hTR beta 1 gene promoter may be involved in the autoregulation of hTR beta 1 gene expression.
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PMID:Cloning and characterization of the human thyroid hormone receptor beta 1 gene promoter. 133 72

The NGFI-B cDNA was previously isolated by virtue of its induction by nerve growth factor (NGF) in PC12 cells. It encodes a 61-kilodalton protein that has two regions of extensive homology with members of the steroid/thyroid hormone receptor gene family. The rat NGFI-B gene is approximately 7.6 kilobases long and is interrupted by six introns. Although the exon-intron structure of the gene is similar to those of several other members of the steroid/thyroid hormone receptor gene family, there is a novel splice site within the DNA-binding domain which suggests that NGFI-B constitutes yet another evolutionary digression from a postulated common ancestral receptor gene. Primer extension and S1 nuclease protection assays were used to determine the transcription initiation site, which displayed the heterogeneity typical of genes that lack a TATA box. Sequence analysis of the 5' flanking region revealed several GC boxes but no identifiable TATA box. Four potential AP1 binding sites were identified at nucleotides -49, -78, -222, and -242. Neither the serum response element nor the CArG box element, two sequences found in other growth factor-inducible genes, was detected in this region of the growth factor-inducible NGFI-B gene. Nevertheless, results of nuclear runoff experiments demonstrated that the NGFI-B gene was transcriptionally activated by nerve growth factor in PC12 cells. In vivo, a rapid, dramatic increase in NGFI-B mRNA was observed in the cerebral cortex, midbrain, and cerebellum of animals that experienced a convulsant-induced seizure.
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PMID:The NGFI-B gene, a transcriptionally inducible member of the steroid receptor gene superfamily: genomic structure and expression in rat brain after seizure induction. 247 23

Autoregulation is a control mechanism common to several proteins of the steroid/thyroid hormone receptor superfamily. In this work, the effect of androgens and antiandrogens on the expression of the human androgen receptor (hAR) in prostate and breast cancer cell lines was studied. Northern blot analysis revealed a decrease in hAR steady state RNA levels in LNCaP cells by 3.3 nM of the synthetic androgen mibolerone. Maximal down-regulation of hAR RNA to 30% of control levels occurred 48 h after hormone addition. T47D breast cancer cells showed a similar effect with mibolerone, while hAR expression in normal skin fibroblasts did not respond to androgen treatment. As shown by nuclease S1 analysis, hAR transcripts initiate at three principal start sites, all of which are equally sensitive to androgen. Steroidal as well as nonsteroidal antiandrogens were capable of partially antagonizing androgen-mediated hAR RNA down-regulation in LNCaP and T47D cells, while not exerting a significant effect when administered alone. While hAR RNA stability was increased by hormone, nuclear run-on analysis revealed a 4-fold reduction of hAR gene transcription 96 h after androgen treatment. Although decreased hAR RNA levels did not coincide with a parallel decrease in AR protein levels, analysis of androgen-inducible reporter constructs demonstrated that prolonged androgen administration to cells results in a progressively impaired sensitivity of the intracellular androgen response mechanism. These results show that prolonged androgen exposure leads, besides its effect on hAR RNA levels, to functional inactivation of the AR. Thus, in vivo, posttranslational control of AR activity appears to be a novel mechanism of negative autoregulation of androgen effects on gene expression.
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PMID:Transcriptional and posttranscriptional regulation of human androgen receptor expression by androgen. 841 17

The c-erbA alpha gene encodes the alpha type thyroid hormone receptor. This gene is expressed in various types of cells, its expression being relatively high in the central nervous system. A genomic clone that contains the 5'-terminal portion of the human c-erbA alpha gene was isolated. The 615 base pair (bp) 5'-flanking sequence of the c-erbA alpha gene showed promoter activity when placed upstream of the bacterial chloramphenicol acetyltransferase gene and transfected into HeLa cells. Nine transcriptional initiation sites were detected within this sequence by S1 nuclease protection analysis. DNA sequence analysis showed that the promoter region contains ten putative binding sites for transcriptional factor Sp1 in the GC rich region (86%). Three putative cAMP responsive elements (CRE) and one putative TPA responsive element (TRE) were identified upstream of the GC rich region. The c-erbA alpha promoter sequence also contains a putative binding site for the Krox-20 transcriptional factor, which is thought to play a role in early development of the mouse central nervous system.
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PMID:Molecular cloning and characterization of the promoter region of the human c-erbA alpha gene. 846 21

nur77 is an immediate-early gene inducible by nerve growth factor or membrane depolarization in the rat pheochromocytoma cell line PC12 and by serum growth factors in fibroblasts. The nur77-encoded protein is a member of the steroid/thyroid hormone receptor superfamily and can act as a potent transcription activator. The induction of nur77 in PC12 cells is rapid and transient, with kinetics similar to those of the c-fos protooncogene. Induction does not require de novo protein synthesis. Whereas transcriptional activation of c-fos by nerve growth factor in PC12 cells requires a 20-base pair serum response element in its promoter, there is no such sequence in the nur77 promoter. To understand the mechanism for the activation of nur77, we have analyzed the inducibility of a series of transfected nur77 minigenes using an S1 nuclease protection assay. We identified the sequence 22-86 nucleotides upstream of the transcription start site as necessary and sufficient for nur77 induction by nerve growth factor and membrane depolarization in PC12 cells. Sequences farther upstream enhance the induction. Analysis of base substitution mutations allowed us to identify three sequence elements within this region that are essential for induction. These sequence elements include two copies of an AP1-like element and a GC-rich sequence. Unlike transcriptional activation of c-fos, the sequence requirements for the activation of nur77 by nerve growth factor and membrane depolarization cannot be readily separated. Taken together, our data suggest that activation of nur77 and c-fos by nerve growth factor occurs through different mechanisms in PC12 cells.
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PMID:Transcriptional activation of the inducible nuclear receptor gene nur77 by nerve growth factor and membrane depolarization in PC12 cells. 847 54

Human TR2 orphan receptor, isolated from the testis and prostate, is a member of the steroid/thyroid hormone receptor superfamily. With the screening of a human genomic library and the combination of primer walking and PCR sequencing, we found that the entire TR2 orphan receptor gene coding region and 5'-untranslated region feature 13 introns and 14 exons, and that the consensus splice sequences (GT-AG) are present in all intron-exon boundaries. Within the region that codes for the DNA binding domain, TR2 orphan receptor gene has a distinct intron-exon junction. Whereas all other known steroid receptors have one splice site that separates their first and second zinc fingers in the DNA binding domain, TR2 orphan receptor has a rare splice site located in the middle of its first zinc finger. The identification of specific junction sequences for potential alternative splicing sites helps to explain the existence of multiple forms of TR2 orphan receptor cDNA (TR2-5, 7, 9, 11). The S1 nuclease protection assay for TR2 message revealed that there are multiple transcription initiations, and that the major cap site surrounded by an initiator-like sequence is located at the 104th nucleotide upstream from the translation start codon. Sequence analysis of a 2.7-kb DNA fragment upstream of the TR2 orphan receptor translation start codon unveiled several potential cis-acting elements, such as AP-1, HNF-5, GATA1 binding sites, and GC boxes. Using fluorescence in situ hybridization combined with a high-resolution G-banding technique, we found that the TR2 orphan receptor gene was mapped to human chromosome 12 at band q22, whereas the structurally closely related TR4 orphan receptor gene was mapped to human chromosome 3 at band q24.3.
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PMID:The genomic structure and chromosomal location of the human TR2 orphan receptor, a member of the steroid receptor superfamily. 970 69