scholarly journals Lithium ions induce prestalk-associated gene expression and inhibit prespore gene expression in Dictyostelium discoideum

1989 ◽  
Vol 93 (1) ◽  
pp. 205-210
Author(s):  
D.J. Peters ◽  
M.M. Van Lookeren Campagne ◽  
P.J. Van Haastert ◽  
W. Spek ◽  
P. Schaap
Keyword(s):  
Gene Expression ◽  
Cyclic Amp ◽  
Dictyostelium Discoideum ◽  
Cysteine Proteinase ◽  
Mrna Levels ◽  
Lithium Ions ◽  
Maximal Inhibition ◽  
Regulated Gene Expression

We investigated the effect of Li+ on two types of cyclic AMP-regulated gene expression and on basal and cyclic AMP-stimulated inositol 1,4,5-triphosphate (Ins(1,4,5)P3) levels. Li+ effectively inhibits cyclic AMP-induced prespore gene expression, half-maximal inhibition occurring at about 2 mM-LiCl. In contrast, Li+ (1–3 mM) promotes the cyclic AMP-induced increase of cysteine proteinase-2 mRNA levels, and induces the expression of this prestalk-associated gene in the absence of cyclic AMP stimuli. At concentrations exceeding 4–5 mM, LiCl inhibits cysteine proteinase-2 gene expression. LiCl reduces basal Ins(1,4,5)P3 levels and decreases the cyclic AMP-induced accumulation of Ins(1,4,5)P3; both effects occur half-maximally at 2–3 mM-LiCl. These results indicate that the induction of the cysteine proteinase-2 gene by Li+ is not due to elevated levels of Ins(1,4,5)P3. It is, however, possible that inhibition of prespore gene expression by Li+ is caused by Li+-induced reduction of basal and/or stimulated Ins(1,4,5)P3 levels.

Pharmacological characterization of cyclic AMP receptors mediating gene regulation in Dictyostelium discoideum

1986 ◽  
Vol 6 (7) ◽  
pp. 2402-2408
Author(s):  
B Haribabu ◽  
R P Dottin
Keyword(s):  
Gene Expression ◽  
Cyclic Amp ◽  
Cell Surface ◽  
Dictyostelium Discoideum ◽  
Cell Surface Receptor ◽  
Intracellular Camp ◽  
Response Curves ◽  
Pharmacological Characterization ◽  
Surface Receptor ◽  
Extracellular Molecules

Extracellular molecules regulate gene expression in eucaryotes. Exogenous cyclic AMP (cAMP) affects the expression of a large number of developmentally regulated genes in Dictyostelium discoideum. Here, we determine the specificity of the receptor(s) which mediates gene expression by using analogs of cAMP. The order of potency with which these analogs affect the expression of specific genes is consistent with the specificity of their binding to a cell surface receptor and is distinct from their affinity for intracellular cAMP-dependent protein kinase. Dose-response curves with cAMP and adenosine 3',5'-monophosphorothioate, a nonhydrolyzable analog, revealed that the requirement for high concentrations of exogenous cAMP for regulating gene expression is due to the rapid degradation of cAMP by phosphodiesterase. The addition of low concentrations of cAMP (100 nM) or analogs in pulses also regulates gene expression. Both the genes that are positively regulated by exogenous cAMP and the discoidin gene, which is negatively regulated, respond to cAMP analogs to the same degree. Genes expressed in prespore or prestalk cells are also similarly regulated. These data suggest that the effects are mediated through the same receptor. The specificity of this receptor is indistinguishable from that of the well-characterized cell surface cAMP receptor.

Regulation of the Discoidin I gamma gene in Dictyostelium discoideum: identification of individual promoter elements mediating induction of transcription and repression by cyclic AMP

1990 ◽  
Vol 10 (8) ◽  
pp. 4080-4088
Author(s):  
F Vauti ◽  
P Morandini ◽  
J Blusch ◽  
A Sachse ◽  
W Nellen
Keyword(s):  
Gene Expression ◽  
Cyclic Amp ◽  
Dictyostelium Discoideum ◽  
Base Pair ◽  
Regulation Of Gene Expression ◽  
Promoter Elements ◽  
Down Regulation ◽  
Heterologous Promoter ◽  
Sequence Element ◽  
Pair Sequence

We dissected the promoter of the developmentally induced and cyclic AMP-repressed discoidin I gamma gene and identified a sequence element essential for developmental induction. Transfer of the element to an inactive heterologous promoter demonstrated that this sequence is sufficient to confer expression in axenically growing cells and to induce gene activity in development after growth on bacteria. A 16-base-pair sequence within this element was shown to be sufficient for induction in the discoidin promoter context and was used to reactivate different truncated promoter constructs. This led to the localization of an element necessary for down regulation of gene expression by extracellular cyclic AMP.

Effect of protein synthesis inhibition on gene expression during early development of Dictyostelium discoideum

1988 ◽  
Vol 8 (1) ◽  
pp. 10-16
Author(s):  
C K Singleton ◽  
S S Manning ◽  
Y Feng
Keyword(s):  
Gene Expression ◽  
Protein Synthesis ◽  
Dictyostelium Discoideum ◽  
Cdna Libraries ◽  
Mrna Levels ◽  
Protein Synthesis Inhibition ◽  
Mutant Strains ◽  
V Genes ◽  
Steady State Levels ◽  
Development Proceeds

Several genes which are deactivated on the initiation of development of Dictyostelium discoideum were identified by differential screening of various cDNA libraries. These genes have in common a decrease in the steady-state levels of their corresponding mRNAs on the onset of development and as development proceeds. When development was carried out in the absence of protein synthesis by inhibition with cycloheximide, the decrease in mRNA levels for most genes (V genes) was normal or slightly accelerated. For about 5% of the genes (H genes), however, cycloheximide caused an apparent induction of expression, as revealed by a slight or dramatic increase in mRNA levels, instead of the normal decrease. This effect was due to inhibition of protein synthesis and not to cycloheximide per se. The induction was found to be due to an enhancement of the transcription rate; normal rates of transcription for the H genes were dependent on continued protein synthesis during vegetative growth and development. Thus, two general regulatory classes exist for deactivation of gene expression on initiation of development, one of which is dependent on and one of which is independent of protein synthesis. Analysis of expression of these genes in mutant strains which are aggregation deficient allowed the classes to be subdivided further. Taken together, these characterizations allow several distinct regulatory mechanisms to be identified that are involved in the deactivation of gene expression on the onset of development in D. discoideum.

Mechanisms of mammalian zinc-regulated gene expression

2008 ◽  
Vol 36 (6) ◽  
pp. 1262-1266 ◽  
Author(s):  
Kelly A. Jackson ◽  
Ruth A. Valentine ◽  
Lisa J. Coneyworth ◽  
John C. Mathers ◽  
Dianne Ford
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Transcriptional Repression ◽  
Mammalian Cells ◽  
Gene Promoter ◽  
Mrna Levels ◽  
Promoter Regions ◽  
Mrna Stabilization ◽  
Transcriptional Regulatory ◽  
Regulated Gene Expression

Mechanisms through which gene expression is regulated by zinc are central to cellular zinc homoeostasis. In this context, evidence for the involvement of zinc dyshomoeostasis in the aetiology of diseases, including Type 2 diabetes, Alzheimer's disease and cancer, highlights the importance of zinc-regulated gene expression. Mechanisms elucidated in bacteria and yeast provide examples of different possible modes of zinc-sensitive gene regulation, involving the zinc-regulated binding of transcriptional activators and repressors to gene promoter regions. A mammalian transcriptional regulatory mechanism that mediates zinc-induced transcriptional up-regulation, involving the transcription factor MTF1 (metal-response element-binding transcription factor 1), has been studied extensively. Gene responses in the opposite direction (reduced mRNA levels in response to increased zinc availability) have been observed in mammalian cells, but a specific transcriptional regulatory process responsible for such a response has yet to be identified. Examples of single zinc-sensitive transcription factors regulating gene expression in opposite directions are emerging. Although zinc-induced transcriptional repression by MTF1 is a possible explanation in some specific instances, such a mechanism cannot account for repression by zinc of all mammalian genes that show this mode of regulation, indicating the existence of as yet uncharacterized mechanisms of zinc-regulated transcription in mammalian cells. In addition, recent findings reveal a role for effects of zinc on mRNA stability in the regulation of specific zinc transporters. Our studies on the regulation of the human gene SLC30A5 (solute carrier 30A5), which codes for the zinc transporter ZnT5, have revealed that this gene provides a model system by which to study both zinc-induced transcriptional down-regulation and zinc-regulated mRNA stabilization.

scholarly journals Regulation of the Discoidin I gamma gene in Dictyostelium discoideum: identification of individual promoter elements mediating induction of transcription and repression by cyclic AMP.

1990 ◽  
Vol 10 (8) ◽  
pp. 4080-4088 ◽  
Author(s):  
F Vauti ◽  
P Morandini ◽  
J Blusch ◽  
A Sachse ◽  
W Nellen
Keyword(s):  
Gene Expression ◽  
Cyclic Amp ◽  
Dictyostelium Discoideum ◽  
Base Pair ◽  
Regulation Of Gene Expression ◽  
Promoter Elements ◽  
Down Regulation ◽  
Heterologous Promoter ◽  
Sequence Element ◽  
Pair Sequence

We dissected the promoter of the developmentally induced and cyclic AMP-repressed discoidin I gamma gene and identified a sequence element essential for developmental induction. Transfer of the element to an inactive heterologous promoter demonstrated that this sequence is sufficient to confer expression in axenically growing cells and to induce gene activity in development after growth on bacteria. A 16-base-pair sequence within this element was shown to be sufficient for induction in the discoidin promoter context and was used to reactivate different truncated promoter constructs. This led to the localization of an element necessary for down regulation of gene expression by extracellular cyclic AMP.

scholarly journals Regulation of cytochrome P450 aromatase gene expression in adult rat Leydig cells: comparison with estradiol production

2001 ◽  
Vol 168 (1) ◽  
pp. 95-105 ◽  
Author(s):  
C Genissel ◽  
J Levallet ◽  
S Carreau
Keyword(s):  
Gene Expression ◽  
Cytochrome P450 ◽  
Cyclic Amp ◽  
Leydig Cell ◽  
Half Life ◽  
Leydig Cells ◽  
Aromatase Activity ◽  
Mrna Levels ◽  
Low Concentrations ◽  
Cytochrome P450 Aromatase

Regulation of aromatase gene expression in purified rat Leydig cells has not yet been investigated. Therefore, using a highly specific quantitative RT-PCR method, we have measured the amount of cytochrome P450 aromatase (P450arom) mRNA and aromatase activity in mature rat Leydig cells submitted to various treatments during 24 h. Estradiol production was enhanced in a dose-related manner in the presence of testosterone, the maximum (28% increase) being obtained with 200 ng/ml. Related to the P450arom mRNA levels, a decrease was observed in the presence of low concentrations (50 and 100 ng/ml) of testosterone, then a 20% increase of the amount of transcripts was recorded for the higher concentrations (200-500 ng/ml). The same result was obtained in the presence of 5alpha-dihydrotestosterone (an androgen resistant to aromatase activity). The addition of ovine LH (oLH; 0.1-50 ng/ml) to the Leydig cell culture medium induced a dose-related augmentation of estradiol output up to 10 ng/ml oLH, although a decrease was observed with 50 ng/ml when compared with maximal values. mRNA levels slightly decreased in the presence of low concentrations (0.1-1 ng/ml) of oLH, an effect that was abolished by the addition of testosterone; mRNA levels were increased by oLH (5-10 ng/ml) 35 and 75% respectively in the absence and presence of testosterone (when compared with Leydig cells incubated without treatment). With 50 ng/ml oLH, a large augmentation (twofold) of the P450arom mRNA level either without or with testosterone was observed. Dibutyryl cyclic AMP (1 mM) mimicked the effect of oLH. The half-life of the P450arom mRNAs was twofold increased in the presence of testosterone and oLH when compared with the half-life in the absence of treatment (5.8+/-0.6 h). Taken together, our data have demonstrated that, in freshly isolated Leydig cells from mature rat testes, the regulation of aromatase expression and enzymatic activity is under LH (through cyclic AMP) and steroid control; moreover seminiferous tubule-secreted factor(s) are also involved. Therefore, rat Leydig cell aromatase is controlled at both transcriptional and post-transcriptional steps by endocrine and/or locally produced modulators.

scholarly journals SAS1 and SAS2, GTP-binding protein genes in Dictyostelium discoideum with sequence similarities to essential genes in Saccharomyces cerevisiae.

1990 ◽  
Vol 10 (5) ◽  
pp. 2367-2378 ◽  
Author(s):  
S A Saxe ◽  
A R Kimmel
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dictyostelium Discoideum ◽  
Intracellular Signaling ◽  
Repetitive Element ◽  
Expression Patterns ◽  
Mrna Levels ◽  
Developmentally Regulated ◽  
Membrane Function ◽  
Gtp Binding ◽  
Regulated Gene Expression

We have identified two novel, very closely related genes, SAS1 and SAS2, from Dictyostelium discoideum. These encode small, approximately 20-kilodaton proteins with amino acid sequences thought to be involved in interaction with guanine nucleotides. The protein sizes, spacings of GTP-binding domains, and carboxyl-terminal sequences suggest their relationship to the ubiquitous ras-type proteins. Their sequences, however, are sufficiently different to indicate that they are not true ras proteins. More extensive sequence identity (approximately 55%) is shared with the YPT1 and SEC4 proteins from Saccharomyces cerevisiae. These yeast proteins are essential for growth and are believed to be involved in intracellular signaling associated with membrane function. SAS1 and SAS2 exhibit distinct patterns of genomic organization and developmentally regulated gene expression. SAS1 contains introns and is associated with a developmentally regulated repetitive element. SAS2 is colinear with its mRNA and does not appear to be closely linked with this repetitive element. Both genes are expressed during growth and throughout development. SAS1 is maximally expressed during cytodifferentiation, when two sizes of SAS1 mRNA are detectable. SAS2 mRNA levels are maximal during culmination. On the basis of the expression patterns of the SAS genes and their relationship to the YPT1 and SEC4 genes, we discuss possible functions of the SAS proteins.

scholarly journals Effect of protein synthesis inhibition on gene expression during early development of Dictyostelium discoideum.

1988 ◽  
Vol 8 (1) ◽  
pp. 10-16 ◽  
Author(s):  
C K Singleton ◽  
S S Manning ◽  
Y Feng
Keyword(s):  
Gene Expression ◽  
Protein Synthesis ◽  
Dictyostelium Discoideum ◽  
Cdna Libraries ◽  
Mrna Levels ◽  
Protein Synthesis Inhibition ◽  
Mutant Strains ◽  
V Genes ◽  
Steady State Levels ◽  
Development Proceeds

Several genes which are deactivated on the initiation of development of Dictyostelium discoideum were identified by differential screening of various cDNA libraries. These genes have in common a decrease in the steady-state levels of their corresponding mRNAs on the onset of development and as development proceeds. When development was carried out in the absence of protein synthesis by inhibition with cycloheximide, the decrease in mRNA levels for most genes (V genes) was normal or slightly accelerated. For about 5% of the genes (H genes), however, cycloheximide caused an apparent induction of expression, as revealed by a slight or dramatic increase in mRNA levels, instead of the normal decrease. This effect was due to inhibition of protein synthesis and not to cycloheximide per se. The induction was found to be due to an enhancement of the transcription rate; normal rates of transcription for the H genes were dependent on continued protein synthesis during vegetative growth and development. Thus, two general regulatory classes exist for deactivation of gene expression on initiation of development, one of which is dependent on and one of which is independent of protein synthesis. Analysis of expression of these genes in mutant strains which are aggregation deficient allowed the classes to be subdivided further. Taken together, these characterizations allow several distinct regulatory mechanisms to be identified that are involved in the deactivation of gene expression on the onset of development in D. discoideum.

Two divergently transcribed genes of Dictyostelium discoideum are cyclic AMP-inducible and coregulated during development

1987 ◽  
Vol 7 (12) ◽  
pp. 4482-4489
Author(s):  
D M Driscoll ◽  
J G Williams
Keyword(s):  
Cyclic Amp ◽  
Nucleic Acids ◽  
Dictyostelium Discoideum ◽  
Dna Sequences ◽  
Intergenic Region ◽  
Cysteine Proteinase ◽  
Transcriptional Level ◽  
Dependent Manner ◽  
Developmentally Regulated ◽  
Reading Frame

The cysteine proteinase 1 (CP1) gene of Dictyostelium discoideum encodes a developmentally regulated sulfhydryl proteinase. We characterized the DNA sequences upstream of the CP1 gene and found a second developmentally regulated gene, which we term DG17. The translational open reading frame of the DG17 gene encoded a 458-amino-acid cysteine- and lysine-rich protein of unknown function. In several regions, the cysteine and lysine residues were arranged in a manner characteristic of the zinc-binding domains found in proteins which interact with nucleic acids. During normal development, the DG17 and CP1 genes are coordinately activated late in aggregation. The addition of exogenous cyclic AMP (cAMP) induced the premature expression of both mRNAs. By measuring the rate of specific mRNA synthesis in isolated nuclei, we showed that cAMP acted at the transcriptional level to activate both genes. The two genes were separated by 910 nucleotides and were divergently transcribed. The intergenic region was predominantly composed of A + T residues except for four short G-rich regions. These sequences coincided with the positions of four nuclease-hypersensitive sites, which appear during aggregation when the DG17 and CP1 genes are transcribed (J. Pavlovic, E. Banz, and R. W. Parish, Nucleic Acids Res. 14:8703-8722, 1986). Two of the G-rich regions formed the core of two almost identical 80-nucleotide repeats located 220 and 320 nucleotides upstream of the CP1 gene. Using the Dictyostelium transformation system, we showed that a restriction fragment containing the intergenic region was capable of directing bidirectional transcription in a cAMP-dependent manner.

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