Showing papers on "Regulation of gene expression published in 1980"
TL;DR: There is now reason to believe, from recent studies, that DNA methylation is a key element in the hierarchy of control mechanisms that govern vertebrate gene function and differentiation.
Abstract: In most higher organisms, DNA is modified after synthesis by the enzymatic conversion of many cytosine residues to 5-methylcytosine. For several years, control of gene activity by DNA methylation has been recognized as a logically attractive possibility, but experimental support has proved elusive. However, there is now reason to believe, from recent studies, that DNA methylation is a key element in the hierarchy of control mechanisms that govern vertebrate gene function and differentiation.
1,907 citations
TL;DR: There appears to exist a striking inverse correlation between the levels of methylation of specific DNA segments and the extent to which these segments are expressed as mRNA, which may provide a clue to understanding the regulation of gene expression in transformed cells and perhaps in eukaryotic cells in general.
Abstract: The adenovirus type 12 (Ad12) DNA sequences integrated into the DNA of four lines of Ad12-transformed hamster cells are extensively methylated. Methylation in mammalian cell DNA is believed to occur predominantly at 5'-C-G-3' sequences. The majority, although not all, of the 5'-C-C-G-G-3' sequences present in integrated Ad12 DNA are methylated. Ad12 DNA isolated from purified virions, on the other hand, is not methylated to any significant extent. The segments of the integrated viral DNA comprising early genes, which are expressed as mRNA in two lines of Ad2-transformed hamster cells, are undermethylated in comparison to late viral segments, which are not expressed and are extensively methylated. In contrast, in two lines of Ad12-induced rat brain tumor cells, some of the late viral genes have been shown to be expressed as mRNA. The segment of the integrated Ad12 DNA that comprises these late genes, the EcoRI B fragment, is undermethylated in comparison to the extensive methylation of the same fragment in Ad12-transformed hamster cells. Thus, there appears to exist a striking inverse correlation between the levels of methylation of specific DNA segments and the extent to which these segments are expressed as mRNA. The functional significance of this correlation remains to be determined. It may provide a clue to understanding the regulation of gene expression in transformed cells and perhaps in eukaryotic cells in general.
270 citations
TL;DR: The Ontogeny of Globin Gene Expression and Molecular Cloning and Repetitive Sequence Elements Within GlobinGene Clusters are reviewed.
Abstract: INTRODUCTION 146 The Ontogeny of Globin Gene Expression 146 Globin Gene Mapping and Molecular Cloning 147 THE HUMAN ,8-LIKE GLOBIN GENES .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. . . . . .. . .. . . . . 148 ,8-Like Globin Gene Fine Structure 148 ,8-Like Globin Gene Linkage . . . .... 151 Repetitive Sequence Elements Within Globin Gene Clusters 153 ,8-Globin Variants .... 153 DNA Sequence Polymorphisms Within the ,8-Like Globin Gene Cluster ..... 154
268 citations
TL;DR: It is shown that replication of the template per se is required for expression of late regions L2--L5 and that the accumulation of early gene products does not suffice and the promoter-proximal late gene block L1 appears to be subject to processing control.
217 citations
TL;DR: By functional tests of in vitro mutated histone DNA in the Xenopus oocyte, it is discovered that the segment E of the A+T-rich spacer DNA lying at a considerable distance upstream of the conservative T-A-T-A of the H2A gene transcription is a strong modulator element of H2a gene transcription.
Abstract: The control region of a sea urchin H2A histone gene may be functionally dissected into at least three DNA segments, which we have termed modulator, selector, and initiator elements. While the initiator and in particular the selector containing the T-A-T-A-A-A-T-A sequence are specificity elements that dictate the generation of faithful 5' ends to H2A mRNA, the modulators control the rate at which these specificity elements operate [Grosschedl, R. & Birnstiel, M. L. (1980) Proc. Natl. Acad. Sci. USA 77, 1432-1436]. By functional tests of in vitro mutated histone DNA in the Xenopus oocyte we have now discovered that the segment E of the A+T-rich spacer DNA lying at a considerable distance upstream of the conservative T-A-T-A-A-A-T-A sequence is a strong modulator element of H2A gene transcription. Deletion of this element creates a 15- to 20-fold H2A-specific down mutation. Segment E by itself cannot elicit initiation of transcription except in coordination with the prelude sequence of the H2A gene. The nucleotide sequence of the relevant spacer element showing modulator activity has been determined and found to contain a pattern of T and A runs as well as a series of inverted repeats. Additional pre-H2A spacer mutants, including a spacer inversion mutant, have been constructed in vitro, that, when injected into the oocyte nucleus, modulate the expression of the H2A gene by an overall factor as large as 100. Other factors controlling promoter activity are discussed.
205 citations
TL;DR: Antiviral activity, whose physico-chemical, immunological and biological characteristics closely corresponded to those of authentic human fibroblast Interferon, was synthesized and processed to a size compatible with mature but unglycosylated authentic product.
Abstract: The human fibroblast interferon gene was inserted in a thermoinducible expression plasmid under control of the phage lambda PL promoter. The primary translation products predicted on the basis of the plasmid constructions were hybrid proteins starting with beta-lactamase or phage MS2 polymerase information followed by the total preinterferon. On induction, antiviral activity, whose physico-chemical, immunological and biological characteristics closely corresponded to those of authentic human fibroblast interferon, was synthesized. Processing to a size compatible with mature but unglycosylated authentic product was observed.
192 citations
TL;DR: A general model for the origin and progression of malignancy is proposed, which states that malignancies originates by changing specific pathways of gene expresion required for growth from inducible to constitutive in cells that can still be induced to differentiate normally by the physiological inducer of differentiation.
Abstract: Chemical carcinogens and tumor promoters have pleiotropic effects. Tumor initiators can produce a variety of mutations and tumor promotres can regulate a variety of physiological molecles that control growth and differentiation. The appropriate mutation and the regulation of the appropriate molecules to induce cell growth can initiate and promote the sequence of changes required for transformation of normal cells into malignant cells. After this sequence of changes, some tumors can still be induced to revert with a high frequency from a malignant phenotype to a nonmalignant phenotype. Results obtained from analysis of regulation of growth and differentiation in normal and leukemic myeloid cells, the phenotypic reversion of malignancy by induction of normal differentiation in myeloid leukemia, and the blocks in differentiation-defective leukemic cell mutants have been used to propose a general model for the origin and progression of malignancy. The model states that malignancy originates by changing specific pathways of gene expresion required for growth from inducible to constitutive in cells that can still be induced to differentiate normally by the physiological inducer of differentiation. The malignant cells, unlike the normal cells, then no longer require the physiological inducer for growth. This changes the requirements for growth and uncouples growth from differentiation. Constitutive expression of other specific pathways can uncouple other controls, which then causes blocks in differentiation and the further progression of malignancy. The existence of specific constitutive pathways of gene expression that uncouple controls in malignant cells can also exlain the expresion of fetal proteins, hormones, and some other specialized products of normal development in various types of tumors.
169 citations
TL;DR: The apo VLDLII and vitellogenin genes appear to be the only genes capable of high rates of expression in the liver that exhibit such an exceptional response to the hormone.
Abstract: Livers of egg-laying species contain abundant mRNAs encoded by both estrogen-responsive and constitutively expressed genes. We have recently constructed cDNA clones from three members of the abundant mRNA class of hen liver. One of these mRNA species was identified as serum albumin mRNA, and another as vitellogenin mRNA. In this study we have identified the third member of the group as apo VLDLII mRNA. Hybridization analyses using cloned cDNA probes indicate that expression of the apo VLDLII gene in rooster liver, like that of the vitellogenin gene, is completely dependent upon the administration of estrogen. The apo VLDLII and vitellogenin genes appear to be the only genes capable of high rates of expression in the liver that exhibit such an exceptional response to the hormone. Administration of estrogen resulted in the appearance of both mRNA species within 30 min, followed by a rapid accumulation to several thousand copies per cell. Removal of the hormone caused a marked destabilization of both vitellogenin mRNA and apo VLDLII mRNA. In contrast, the absolute levels of serum albumin mRNA were unaffected by the hormone. Comparative studies on the structure and organization of these three genes may reveal elements involved in determining their rates of expression in the presence and absence of estrogen.
164 citations
TL;DR: The degree of CpG methylation in the rabbit beta-like globin gene cluster is correlated with gene activity, but the effect is confined to relatively small regions of DNA.
Abstract: The relationship between DNA methylation and differential expression of rabbit beta-like globin genes was studied by using restriction enzymes that cleave the sequence C-C-G-G but are differentially inhibited by the presence of 5-methylcytosine. The methylation frequency of 13 C-C-G-G sites that flank a set of four closely linked rabbit beta-like globin genes was determined. This analysis revealed that certain sites surrounding embryonic and adult globin genes are relatively undermethylated in DNA from embryonic and adult erythroid tissues, respectively. This pattern is most pronounced for three sites that are undermethylated in erythroid cells but are totally methylated in nonerythroid cells. We conclude that the degree of CpG methylation in the rabbit beta-like globin gene cluster is correlated with gene activity, but the effect is confined to relatively small regions of DNA.
141 citations
TL;DR: Guarente et al. as mentioned in this paper applied the method of Guarente and Ptashne to construct plasmids that direct expression in Escherichia coli of the human fibroblast interferon (F-IF) gene.
Abstract: We applied the method of Guarente et al. [Guarente, L., Lauer, G., Roberts, T.M. & Ptashne, M. (1980) Cell 20, 543-553] to construct plasmids that direct expression in Escherichia coli of the human fibroblast interferon (F-IF) gene. Two plasmids were recovered. One directs efficient synthesis of a protein whose primary sequence is that of pre-F-IF and the other, that of mature F-IF. Extracts of bacteria synthesizing mature F-IF display antiviral activity characteristic of human F-IF. This activity is lower than that expected from the differential rate of synthesis of the protein. We have detected no such activity in extracts of bacteria synthesizing pre-F-IF.
138 citations
TL;DR: A mixture of two recombinant plasmids was microinjected into mouse thymidine kinase-negative fibroblasts and these cells were shown to produce functionally active herpes simplex type I thymine kinase enzyme, replicate the human beta globin gene, and produce humanbeta globin mRNA sequences at low levels.
Abstract: A mixture of two recombinant plasmids was microinjected into mouse thymidine kinase-negative fibroblasts (L cells). One plasmid contained the thymidine kinase gene of herpes simplex virus type I and the other contained the human beta globin gene. Seven fibroblast colonies arising from injected cells incubated in hypoxanthine/aminopterin/thymidine medium were analyzed. These microinjected cells were shown to: (i) produce functionally active herpes simplex type I thymidine kinase enzyme, (ii) replicate the human beta globin gene, and (iii) produce human beta globin mRNA sequences at low levels. Thus, the genetic defect (lack of thymidine kinase activity) was corrected by the microinjected thymidine kinase gene, and a coinjected human beta globin gene was replicated and weakly expressed.
TL;DR: It is concluded that the guanine nucleotide regulatory protein is necessary for fluoride activation of adenylate cyclase and that the nature of the Guanineucleotide bound at the regulatory site influences fluoride stimulation.
TL;DR: The results suggest that the modification of either histones or other unidentified regulatory proteins by acetylation may play a role in the mechanism of estrogen-mediated gene induction.
TL;DR: This chapter defines and discusses the mapping of adenovirus 2 nuclear transcription, which allows a relationship to be established between DNA structure, mRNA location, and definition of transcription units responsible for mRNA production.
Abstract: Publisher Summary This chapter defines and discusses the mapping of adenovirus 2 nuclear transcription. The immediate products of genes in mammalian cells are not used directly as mRNA but undergo extensive posttranscriptional modifications. At the level of transcription, the control of gene expression in mammalian cells may involve the posttranscriptional modifications. Therefore, any step concerned with processing of a nuclear precursor molecule can potentially be involved in the regulation of gene expression. Adenovirus-infected HeLa cells provide an ideal system for studying the formation of primary RNA transcripts. Adenovirus is an excellent model system for the study of the formation of primary transcripts because of the availability of highly refined physical maps of the adenovirus 2 genome that have been obtained using restriction endonucleases. This then allows a relationship to be established between DNA structure, mRNA location, and definition of transcription units responsible for mRNA production.
TL;DR: The structural genes for Escherichia coli ribosomal protein (r-protein) genes L1, S4, and S11 were inserted into a plasmid vector containing the lac operator and promoter such that the synthesis was controlled by lac regulatory elements to support the hypothesis that certain r-proteins have the capacity to selectively inhibit synthesis of r- Proteins whose genes are in the same operon as their own.
Abstract: The structural genes for Escherichia coli ribosomal protein (r-protein) genes L1, S4, and S11 were inserted into a plasmid vector containing the lac operator and promoter such that the synthesis of L1, S4, and S11 was controlled by lac regulatory elements. Synthesis of L1, S4, and S11 was stimulated by addition of an inducer of the lac operon (isopropyl thiogalactoside) to exponentially growing cells. Elevated synthesis of L1 caused a specific decrease in L11 synthesis, whereas overproduction of S4 resulted in lowered synthesis of S13 and L17. Stimulation of L1 or S4 synthesis also inhibited cell growth. Overproduction of S11 did not affect synthesis of other r-proteins or alter growth. These results confirm previous in vitro studies [Yates, J. L., Arfsten, A. E. & Nomura, M. (1980) Proc. Natl. Acad. Sci. USA 77, 1837-1841] and support the hypothesis that certain r-proteins have the capacity to selectively inhibit synthesis of r-proteins whose genes are in the same operon as their own.
TL;DR: Deletion mutants of this plasmid are made, from which the major cap sites of SV40 early mRNAs have been removed along with some of the sequences upstream, and the deleted sequences appear to be dispensable for early gene expression.
Abstract: A recombinant plasmid was constructed by insertion of the early genes of simian virus 40 (SV40) into pBR322. When it was introduced into eukaryotic cells, the SV40 early genes were expressed. We have made deletion mutants of this plasmid, from which the major cap sites of SV40 early mRNAs have been removed along with some of the sequences upstream. The deleted sequences appear to be dispensable for early gene expression, but this does not necessarily imply that they serve no function in the initiation of transcription on wild-type SV40.
TL;DR: For the several birA mutants examined, there appeared to be no direct correlation between effects on minimum biotin requirement and alterations in repressibility, suggesting a possible dual function for the gene.
Abstract: The technique developed by Casadaban (M. J. Casadaban, J. Mol. Biol. 104: 541-555, 1976) has been employed to construct Escherichia coli K-12 derivatives in which the genes determining lactose utilization are fused to the regulatory region of the biotin operon. Fusions of the lac genes to either arm of this divergently transcribed operon have been isolated. When the operon is derepressed, expression of the lac genes is sufficient to permit growth on lactose minimal medium. Repressing conditions prevent growth on lactose. This property of bio-lac fusion strains, as well as the ease of determining the level of operon expression by assaying beta-galactosidase, was used for the isolation and characterization of mutants defective in repression. Preliminary analyses of several newly isolated regulatory mutants are presented. For the several birA mutants examined, there appeared to be no direct correlation between effects on minimum biotin requirement and alterations in repressibility, suggesting a possible dual function for the gene. Parallel attempts to obtain fusions of lac to bioH were unsuccessful, indicating lack of direct biotin control at the bioH locus.
TL;DR: In this paper, it was shown that plasmid-encoded polypeptide (E3) induction is regulated post-transcriptionally in the sense that it can occur when RNA synthesis is blocked and that induction is accompanied by an increase in the functional half-life of E3 mRNA but not of the remaining four known pE194 polyPEptides.
Abstract: Induction of the synthesis of a plasmid-encoded polypeptide (E3) by erythromycin is known to be required for the inducible expression of resistance to the macrolide-lincosamide-streptogramin B group of antibiotics in Bacillus subtilis strains carrying the plasmid pE194. This resistance is mediated by a specific N6-dimethylation of adenine in the 23S rRNA of the large ribosomal subunit. We show in this report that E3 induction is regulated posttranscriptionally in the sense that it can occur when RNA synthesis is blocked and that induction is accompanied by an increase in the functional half-life of E3 mRNA but not of the mRNA species that code for the remaining four known pE194 polypeptides. The induction of E3 is subject to feedback regulation and involves the ribosome. Modification of the erythromycin binding site on the ribosome by methylation or by mutation interferes with induction.
TL;DR: In this paper, the authors defined a discrete site, tR1, in the y region of λ at which transcription termination occurs in vivo and compared with the previously described in vitro termination reaction.
TL;DR: New aspects of interactions between various combinations of Sxl and da alleles are explored in order to understand better the complex da phenotype, and a new class of subliminal Sxlf alleles is described.
Abstract: Sex-lethal (Sxl) is a vital, X-chromosome gene involved in Drosophila sex determination. The most striking aspect of the phenotype of daughterless (da), an autosomal maternal-effect mutation, may be explained by effects on the functioning of the Sxl gene in the zygote. In this paper, new aspects of interactions between various combinations of Sxl and da alleles are explored in order to understand better the complex da phenotype. The study focuses on the relationship between maternal and zygotic da+ gene functions, and on the relationship between aspects of the da phenotype that are sex-specific and aspects that are not. The SxlM#1 allele, which counteracts the female-specific maternal effect of da, is shown to have no effect on two other aspects of the da phenotype (one maternal, one primarily zygotic) that are not sex-specific. The female-lethal da maternal effect is shown to kill daughters even when the progeny are entirely wild-type with respect to da. Recessive mutant alleles of the two genes can interact synergistically when both are heterozygous with their wild-type alleles, disrupting the development of most of the daughters. Surprisingly, even a deficiency of the da+ locus can produce a dominant, temperature-sensitive, female-lethal maternal effect. A new class of subliminal Sxlf alleles is described. These spontaneous mutations can confuse analysis of both da and Sxl if their presence is not appreciated. Finally, conditions are described that facilitate the study of the Enhancer of daughterless mutation.
TL;DR: The results provide strong direct evidence for rapid evolution of new patterns of gene regulation in this group of organisms and the adaptive significance of these pattern differences is unknown.
Abstract: The tissue and stage specificity of expression of five enzymes was examined by electrophoretic analysis of relative enzyme levels in extracts of 13 larval and adult tissues in 27 species of Hawaiian picture-wingedDrosophila. The developmentally regulated patterns of enzyme expression thus characterized were compared to a modal standard phenotype. About 30% of the pattern features analyzed differed significantly from the standard in one or more species. Many of these regulatory differences are essentially qualitative, with tissue specific differences in enzyme activity in excess of 100 fold for some species pairs. The adaptive significance of these pattern differences is unknown, but the results provide strong direct evidence for rapid evolution of new patterns of gene regulation in this group of organisms.
TL;DR: One of the suspected regulators of glutamine synthetase [L-glutamate:ammonia ligase (ADP-forming), EC 6.3.1.2] in enteric bacteria is glutamine Synthetase itself, which is isolated from Escherichia coli strains carrying fusions of the beta-galactosidase structural gene to the promoter of the glutaminesynthetase gene.
Abstract: One of the suspected regulators of glutamine synthetase [L-glutamate:ammonia ligase (ADP-forming), EC 6.3.1.2] in enteric bacteria is glutamine synthetase itself. We isolated Escherichia coli strains carrying fusions of the beta-galactosidase structural gene to the promoter of the glutamine synthetase gene, with the aid of the Casadaban Mud1 (ApR, lac, cts62) phage. Some aspects of regulation were retained in haploid fusion strains despite the absence of glutamine synthetase, whereas other aspects required glutamine synthetase catalytic or regulatory activity or both. The direction of transcription of the glutamine synthetase gene was also determined.
TL;DR: Analysis of protein changes using two-dimensional polyacrylamide gel electrophoresis concluded that differentiation consists of multiple, parallel, separately programmed pathways of gene expression.
TL;DR: A stem cell is constructed which contains a set of genes (SV40), the expression of which is regulated differently in stem and differentiated cells, which could be used to determine the mechanism of suppression of expression of these genes in stem cells.
Abstract: Thymidine kinase-deficient (TK-; ATP:thymidine 5'-phosphotransferase, EC 2.7.1.21)F9 teratocarcinoma stem cells have been transformed with a recombinant plasmid genome consisting of the pBR322 genome linked to a herpes simplex virus type 1 thymidine kinase gene (HSV-1 tk) and a simian virus 40 (SV40) genome. A clonal line of stem cells was obtained that contains only one copy of plasmid DNA, which is integrated into murine chromosomal DNA through a site on the pBRR322 genome. The HSV-1 tk gene, which is adjacent to the SV40 genome, is expressed in stem cells, whereas SV40 gene expression is not detectable. If differentiation of these stem cells is induced, the differentiated cells express SV40 early gene products. Thus, we have constructed a stem cell which contains a set of genes (SV40), the expression of which is regulated differently in stem and differentiated cells. This cell line could be used to determine the mechanism of suppression of expression of these genes in stem cells.
TL;DR: It would appear that the expression of qualitatively new sequences at the polysomal level is controlled transcriptionally and not post-transcriptionally, and support for this conclusion was furnished by experiments where chromatin from EC and Mb cells was partially digested with DNase I.
TL;DR: Cyclic AMP, via a specific receptor protein, plays an important role in the regulation of gene expression in bacteria and might behave as a general modulator of gene dosage, through modulation of transcription termination efficiency.
TL;DR: The structure of the chick alpha-actin gene differs, therefore, from the structures of actin genes from yeast and Drosophila, both of which contain a single, relatively long, intervening sequence.
Abstract: Recombinant DNA clones containing chick alpha-actin mRNA sequence have been isolated and used as probes to analyze the structure and developmental expression of the chick alpha-actin gene. The full length, 2000 nucleotide alpha-actin mRNA is detected in poly(A) RNA at early and late stages of in vivo leg muscle development. As expected, the alpha-actin mRNA is present at very low levels at early myogenic stages but is a high abundance species in terminally differentiated muscle. However, most of the alpha-actin mRNA from fused leg muscle is shorter than 2000 nucleotides, and occurs in relatively discrete size classes. An alpha-actin-like mRNA can be detected in poly(A) RNA from early embryonic brain, indicating that transcription of the alpha-actin gene may not be strictly muscle-specific at all stages of development. We have identified at least 3, very short (< 100 base pairs) intervening sequences in the alpha-actin gene which was isolated from a chick genomic library. The structure of the chick alpha-actin gene differs, therefore, from the structures of actin genes from yeast and Drosophila, both of which contain a single, relatively long, intervening sequence.
TL;DR: The proposed plasmid instability arose as a direct consequence of the metabolic effects of an overproduction of the enzymes coded for by the tyrosine operon, and the results suggest a role for IS1 elements in the regulation of gene expression.
Abstract: The transformation of tyrR strains of Escherichia coli with multicopy plasmids which carry the tyrosine operon gave rise to modified plasmids with either insertions or deletions. The effect of each of these insertions or deletions was to decrease the level of expression of this operon. It is proposed that plasmid instability arose as a direct consequence of the metabolic effects of an overproduction of the enzymes coded for by the tyrosine operon. The results have significant implications for the cloning of genes that are repressed by the product of a regulatory gene. Since the predominant plasmid modification observed was the insertion of an IS1 element near the regulatory region of the tyrosine operon, the results also suggest a role for IS1 elements in the regulation of gene expression.
TL;DR: The transient, premature accumulation of the mRNA occurs in concert with the onset of amplification of its specific gene, a finding suggestive of a functional coupling between the two events.
Abstract: In the cytoplasm of follicular cells of female fruitflies, a messenger RNA for one of the chorion proteins accumulates prematurely (i.e, before in vivo synthesis of the protein) but is not associated with polysomes. Subsequently, this mRNA is rapidly degraded and, thus, is not stored for later use. At a later stage in choriogenesis, the same mRNA reappears, accumulates, associates with polysomes, and is translated into a chorion protein. The transient, premature accumulation of the mRNA occurs in concert with the onset of amplification of its specific gene, a finding suggestive of a functional coupling between the two events.
TL;DR: Wholesale alterations in the degradation rates of total and at least specific messages do not appear to play a role in the regulation of gene expression during Dictyostelium development.