scholarly journals Butyrate-induced changes in nuclease sensitivity of chromatin cannot be correlated with transcriptional activation.

1987 ◽  
Vol 7 (11) ◽  
pp. 3863-3870 ◽  
Author(s):  
B W Birren ◽  
S J Taplitz ◽  
H R Herschman
Keyword(s):  
Transcriptional Activation ◽  
Hepatoma Cell ◽  
Dnase I ◽  
Micrococcal Nuclease ◽  
Hepatoma Cell Line ◽  
Butyrate Treatment ◽  
Dnase I Sensitivity ◽  
Induced Changes ◽  
I Gene ◽  
Nuclease Sensitivity

We examined in the H4IIE rat hepatoma cell line the relationship between butyrate-induced changes in the nuclease sensitivity of chromatin and changes in transcriptional activity of specific genes. The butyrate-inducible metallothionein I (MT-I) gene underwent a dramatic increase in DNase I sensitivity after 3 h of butyrate treatment. However, genes not transcribed in H4IIE cells underwent the same changes in DNase I sensitivity. Thus, butyrate-induced increases in DNase I sensitivity are not sufficient for the transcriptional activation of a gene. Butyrate treatment has also been reported to alter the sensitivity of sequences to micrococcal nuclease (MNase) in a manner reflecting their tissue-specific expression. Butyrate exposure caused increased digestion of the MT-I gene by MNase. However, butyrate-induced MNase sensitivity also occurred for genes which are neither transcribed in untreated cells nor butyrate inducible. Moreover, cadmium, a potent transcriptional activator of the MT-I gene, does not alter the sensitivity of the MT-I gene to MNase. Thus, the butyrate-induced alterations in MNase sensitivity are neither sufficient for, necessary for, nor indicative of transcriptional activation.

Butyrate-induced changes in nuclease sensitivity of chromatin cannot be correlated with transcriptional activation

1987 ◽  
Vol 7 (11) ◽  
pp. 3863-3870
Author(s):  
B W Birren ◽  
S J Taplitz ◽  
H R Herschman
Keyword(s):  
Transcriptional Activation ◽  
Hepatoma Cell ◽  
Dnase I ◽  
Micrococcal Nuclease ◽  
Hepatoma Cell Line ◽  
Butyrate Treatment ◽  
Dnase I Sensitivity ◽  
Induced Changes ◽  
I Gene ◽  
Nuclease Sensitivity

We examined in the H4IIE rat hepatoma cell line the relationship between butyrate-induced changes in the nuclease sensitivity of chromatin and changes in transcriptional activity of specific genes. The butyrate-inducible metallothionein I (MT-I) gene underwent a dramatic increase in DNase I sensitivity after 3 h of butyrate treatment. However, genes not transcribed in H4IIE cells underwent the same changes in DNase I sensitivity. Thus, butyrate-induced increases in DNase I sensitivity are not sufficient for the transcriptional activation of a gene. Butyrate treatment has also been reported to alter the sensitivity of sequences to micrococcal nuclease (MNase) in a manner reflecting their tissue-specific expression. Butyrate exposure caused increased digestion of the MT-I gene by MNase. However, butyrate-induced MNase sensitivity also occurred for genes which are neither transcribed in untreated cells nor butyrate inducible. Moreover, cadmium, a potent transcriptional activator of the MT-I gene, does not alter the sensitivity of the MT-I gene to MNase. Thus, the butyrate-induced alterations in MNase sensitivity are neither sufficient for, necessary for, nor indicative of transcriptional activation.

scholarly journals Alternative inducers of the rat metallothionein I gene cause distinct changes in chromatin structure in the 5' region of the gene.

1986 ◽  
Vol 6 (7) ◽  
pp. 2576-2581 ◽  
Author(s):  
S J Taplitz ◽  
K L Calame ◽  
H R Herschman
Keyword(s):  
Chromatin Structure ◽  
Hepatoma Cell ◽  
Regulatory Elements ◽  
Dnase I ◽  
Hepatoma Cell Line ◽  
Hypersensitive Site ◽  
Level Control ◽  
Dnase I Hypersensitive Site ◽  
Rat Hepatoma Cell Line ◽  
I Gene

We examined the chromatin structure of the rat metallothionein I gene, both in uninduced cells and in cells induced by heavy metals or dexamethasone, using hypersensitivity to DNase I as an assay. The metallothionein I gene of the H4IIE rat hepatoma cell line, expressed at basal level, has a single DNase I-hypersensitive site. This site maps between putative hormone and basal level control sequences. Induction of the gene by cadmium or zinc resulted in the appearance of a new hypersensitive site near the start site of transcription, in a region near the metal-regulatory elements. In contrast, induction of the metallothionein I gene by dexamethasone did not alter the basal pattern of hypersensitivity. Thus, different mechanisms of induction of metallothionein transcription lead to distinct alterations in the chromatin containing the 5' sequences regulating the expression of this gene.

Alternative inducers of the rat metallothionein I gene cause distinct changes in chromatin structure in the 5' region of the gene

1986 ◽  
Vol 6 (7) ◽  
pp. 2576-2581
Author(s):  
S J Taplitz ◽  
K L Calame ◽  
H R Herschman
Keyword(s):  
Chromatin Structure ◽  
Hepatoma Cell ◽  
Regulatory Elements ◽  
Dnase I ◽  
Hepatoma Cell Line ◽  
Hypersensitive Site ◽  
Level Control ◽  
Dnase I Hypersensitive Site ◽  
Rat Hepatoma Cell Line ◽  
I Gene

We examined the chromatin structure of the rat metallothionein I gene, both in uninduced cells and in cells induced by heavy metals or dexamethasone, using hypersensitivity to DNase I as an assay. The metallothionein I gene of the H4IIE rat hepatoma cell line, expressed at basal level, has a single DNase I-hypersensitive site. This site maps between putative hormone and basal level control sequences. Induction of the gene by cadmium or zinc resulted in the appearance of a new hypersensitive site near the start site of transcription, in a region near the metal-regulatory elements. In contrast, induction of the metallothionein I gene by dexamethasone did not alter the basal pattern of hypersensitivity. Thus, different mechanisms of induction of metallothionein transcription lead to distinct alterations in the chromatin containing the 5' sequences regulating the expression of this gene.

scholarly journals Acetylation of a Specific Promoter Nucleosome Accompanies Activation of the ɛ-Globin Gene by β-Globin Locus Control Region HS2

2001 ◽  
Vol 21 (4) ◽  
pp. 1155-1163 ◽  
Author(s):  
Chang-Yun Gui ◽  
Ann Dean
Keyword(s):  
Control Region ◽  
Dna Sequences ◽  
Transcriptional Activation ◽  
Trichostatin A ◽  
Globin Gene ◽  
Chromatin Modification ◽  
Locus Control Region ◽  
Micrococcal Nuclease ◽  
Nuclease Sensitivity

ABSTRACT On stably replicating episomes, transcriptional activation of the ɛ-globin promoter by the β-globin locus control region HS2 enhancer is correlated with an increase in nuclease sensitivity which is limited to the TATA-proximal nucleosome (N1). To elucidate what underlies this increase in nuclease sensitivity and the link between chromatin modification and gene expression, we examined the nucleoprotein composition and histone acetylation status of transcriptionally active and inactive promoters. Micrococcal nuclease digestion of active promoters in nuclei released few nucleosome-like nucleoprotein complexes containing N1 sequences in comparison to results with inactive promoters. We also observed that N1 DNA fragments from active promoters are of a subnucleosomal length. Nevertheless, chromatin immunoprecipitation experiments indicate that histones H3 and H4 are present on N1 sequences from active promoters, with H3 being dramatically hyperacetylated compared with that from inactive promoters and vector sequences. Strikingly, H3 in the adjacent upstream nucleosome (N2) does not appear to be differentially acetylated in active and inactive promoters, indicating that the nucleosome modification of the promoter that accompanies transactivation by HS2 is highly directed and specific. However, global acetylation of histones in vivo by trichostatin A did not activate transcription in the absence of HS2, suggesting that HS2 contributes additional activities necessary for transactivation. N1 sequences from active promoters also contain reduced levels of linker histone H1. The detection of a protected subnucleosomal sized N1 DNA fragment and the recovery of N1 DNA sequences in immunoprecipitations using anti-acetylated H3 and H4 antibodies argue that N1 is present, but in an altered conformation, in the active promoters.

scholarly journals The extracellular matrix coordinately modulates liver transcription factors and hepatocyte morphology.

1991 ◽  
Vol 11 (9) ◽  
pp. 4405-4414 ◽  
Author(s):  
C M DiPersio ◽  
D A Jackson ◽  
K S Zaret
Keyword(s):  
Extracellular Matrix ◽  
Transcription Factors ◽  
Cell Line ◽  
Cell Morphology ◽  
Transcriptional Activation ◽  
Hepatoma Cell ◽  
Collagen Gel ◽  
Hepatoma Cell Line ◽  
Transcriptional Enhancer ◽  
Mrna Accumulation

The extracellular matrix (ECM) promotes tissue morphogenesis, cell migration, and the differentiation of a variety of cell types. However, the mechanisms by which ECM causes differentiated gene expression have been unknown. In this report, we show that culturing the hepatocyte-derived cell line H2.35 on an ECM gel changes cell morphology and selectively stimulates the transcription of a subset of liver-specific genes, including serum albumin. Transcriptional activation by ECM also occurs with transfected plasmids bearing the transcriptional enhancer of the albumin gene. ECM substrates of different composition activated the albumin enhancer only when the ECM promoted a cuboidal, differentiated cell morphology. Enhancer activation by the ECM was mediated by two liver transcription factors, HNF3 alpha and eH-TF, which appear to be regulated differently by matrix. Specifically, we found that a collagen gel substratum caused a selective increase in the factor HNF3 alpha at the levels of mRNA accumulation and DNA-binding activity in nuclear extracts, both in H2.35 cells and in the hepatoma cell line HepG2. We conclude that the ECM can stimulate cell differentiation by selectively activating transcriptional regulatory factors and that such regulation occurs coordinately with ECM-promoted changes in cell shape.

scholarly journals Transcriptional Activation of Chac1 and Other Atf4-Target Genes Induced by Extracellular l-Serine Depletion is negated with Glycine Consumption in Hepa1-6 Hepatocarcinoma Cells

Nutrients ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 3018
Author(s):  
Momoko Hamano ◽  
Shozo Tomonaga ◽  
Yusuke Osaki ◽  
Hiroaki Oda ◽  
Hisanori Kato ◽  
...  
Keyword(s):  
Transcriptional Activation ◽  
Target Genes ◽  
De Novo ◽  
Hepatoma Cell ◽  
Cell Types ◽  
Hepatoma Cell Line ◽  
Rapid Reduction ◽  
Altered Expression ◽  
Hepatocarcinoma Cells ◽  
Expression Program

Mouse embryonic fibroblasts lacking D-3-phosphoglycerate dehydrogenase (Phgdh), which catalyzes the first step of de novo synthesis of l-serine, are particularly sensitive to depletion of extracellular L-serine. In these cells, depletion of l-serine leads to a rapid reduction of intracellular L-serine, cell growth arrest, and altered expression of a wide variety of genes. However, it remains unclear whether reduced availability of extracellular l-serine elicits such responses in other cell types expressing Phgdh. Here, we show in the mouse hepatoma cell line Hepa1-6 that extracellular l-serine depletion transiently induced transcriptional activation of Atf4-target genes, including cation transport regulator-like protein 1 (Chac1). Expression levels of these genes returned to normal 24 h after l-serine depletion, and were suppressed by the addition of l-serine or glycine in the medium. Extracellular l-serine depletion caused a reduction of extracellular and intracellular glycine levels but maintained intracellular l-serine levels in the cells. Further, Phgdh and serine hydroxymethyltransferase 2 (Shmt2) were upregulated after l-serine depletion. These results led us to conclude that the Atf4-mediated gene expression program is activated by extracellular l-serine depletion in Hepa1-6 cells expressing Phgdh, but is antagonized by the subsequent upregulation of l-serine synthesis, mainly from autonomous glycine consumption.

scholarly journals Tracking chromatin states using controlled DNase I treatment and real-time PCR

2007 ◽  
Vol 12 (4) ◽  
Author(s):  
Rui Martins ◽  
Adrian Platts ◽  
Stephen Krawetz
Keyword(s):  
Sensitivity Analysis ◽  
Real Time ◽  
Real Time Pcr ◽  
Rapid Analysis ◽  
Dnase I ◽  
Genomic Changes ◽  
Novel Approach ◽  
Dnase I Sensitivity ◽  
Multiple Samples ◽  
Nuclease Sensitivity

AbstractA novel approach to DNase I-sensitivity analysis was applied to examining genes of the spermatogenic pathway, reflective of the substantial morphological and genomic changes that occur during this program of differentiation. A new real-time PCR-based strategy that considers the nuances of response to nuclease treatment was used to assess the nuclease susceptibility through differentiation. Data analysis was automated with the K-Lab PCR algorithm, facilitating the rapid analysis of multiple samples while eliminating the subjectivity usually associated with Ct analyses. The utility of this assay and analytical paradigm as applied to nuclease-sensitivity mapping is presented.

THE REGULATION OF FIBRINOGEN PRODUCTION INVOLVES AT LEAST ONE OTHER HEPATOCYTE GENE

1987 ◽  
Author(s):  
P M Fowlkes ◽  
P K Lund ◽  
M Blake ◽  
J Snouwaert
Keyword(s):  
Gene Product ◽  
Transcriptional Activation ◽  
Hepatoma Cell ◽  
Fold Increase ◽  
Published Data ◽  
Hepatoma Cell Line ◽  
Mrna Levels ◽  
Additional Increase ◽  
Acute Phase Reactants ◽  
Hypophysectomized Rats

It is currently thought that glucocorticosteriods have a direct effect on the transcription of the alpha, beta and gamma fibrinogen genes. However, our studies indicate that while corticosteriods play a role in fibrinogen production, this role is not due to transcriptional activation via glucocorticosteriod receptors. In initial experiments, we compared the levels of fibrinogen mRNA in hepatocytes isolated from hypophysectomized rats to those from control animals. The levels of mRNA in hypophysectomized rats, which produce little ACTH or corticosteriods, were significantly higher than the levels in control animals. Albumin mRNA levels were unaffected by hypophysectomy. These results are in opposition to those which we had anticipated. Based on previously published data, we had thought that physiologic deprivation of corticosteriods would lead to decreased levels of fibrinogen. We propose that these results are related to the negative feedback that corticosteroids have on Hepatocyte Stimulating Factor (HSF) production through a tightly controlled feedback circuit. To investigate the role of corticosteriods in fibrinogen gene regulation, we have conducted experiments with primary hepatocytes in culture and rat FAZA cells (continuous hepatoma cell line). There is a 4 to 5 fold increase in fibrinogen production when these cells are treated with HSF but no change when these cells are treated with dexamethasone alone. However, there is a marked additional increase in the production of fibrinogen with the combination of dexamethasone and HSF. Data gathered through kinetic analysis of this synergistic interaction suggest that the maximum response to HSF requires another gene product whose production is responsive to dexamethasone. Detailed analysis of the rate of transcription of thegamma fibrinogen gene, its processing and mRNA turnover suggests a specific role for this gene product in regulating fibrinogen synthesis. Characterization of this gene product will lead to greater understanding of the regulation of the Acute Phase Reactants.

Sign in / Sign up

Export Citation Format

Share Document