scholarly journals Evidence That Runt Acts as a Counter-Repressor of Groucho During Drosophila melanogaster Primary Sex Determination

2020 ◽  
Vol 10 (7) ◽  
pp. 2487-2496
Author(s):  
Sharvani Mahadeveraju ◽  
Young-Ho Jung ◽  
James W. Erickson
Keyword(s):  
Drosophila Melanogaster ◽  
Sex Determination ◽  
Transcriptional Repression ◽  
Biological Effects ◽  
Regulatory Gene ◽  
Animal Cells ◽  
Interaction Domain ◽  
Link Type ◽  
High Level ◽  
Runx Proteins

Runx proteins are bifunctional transcription factors that both repress and activate transcription in animal cells. Typically, Runx proteins work in concert with other transcriptional regulators, including co-activators and co-repressors to mediate their biological effects. In Drosophila melanogaster the archetypal Runx protein, Runt, functions in numerous processes including segmentation, neurogenesis and sex determination. During primary sex determination Runt acts as one of four X-linked signal element (XSE) proteins that direct female-specific activation of the establishment promoter (Pe) of the master regulatory gene Sex-lethal (Sxl). Successful activation of SxlPe requires that the XSE proteins overcome the repressive effects of maternally deposited Groucho (Gro), a potent co-repressor of the Gro/TLE family. Runx proteins, including Runt, contain a C-terminal peptide, VWRPY, known to bind to Gro/TLE proteins to mediate transcriptional repression. We show that Runt’s VWRPY co-repressor-interaction domain is needed for Runt to activate SxlPe. Deletion of the Gro-interaction domain eliminates Runt-ability to activate SxlPe, whereas replacement with a higher affinity, VWRPW, sequence promotes Runt-mediated transcription. This suggests that Runt may activate SxlPe by antagonizing Gro function, a conclusion consistent with earlier findings that Runt is needed for Sxl expression only in embryonic regions with high Gro activity. Surprisingly we found that Runt is not required for the initial activation of SxlPe. Instead, Runt is needed to keep SxlPe active during the subsequent period of high-level Sxl transcription suggesting that Runt helps amplify the difference between female and male XSE signals by counter-repressing Gro in female, but not in male, embryos.

scholarly journals Evidence that Runt Acts as a Counter-Repressor of Groucho during Drosophila melanogaster Primary Sex Determination

2019 ◽  
Author(s):  
Sharvani Mahadeveraju ◽  
James W. Erickson
Keyword(s):  
Drosophila Melanogaster ◽  
Sex Determination ◽  
Transcriptional Repression ◽  
Biological Effects ◽  
Regulatory Gene ◽  
Animal Cells ◽  
Interaction Domain ◽  
The Difference ◽  
High Level ◽  
Runx Proteins

AbstractRunx proteins are bifunctional transcription factors that both repress and activate transcription in animal cells. Typically Runx proteins work in concert with other transcriptional regulators, including co-activators and co-repressors to mediate their biological effects. In Drosophila melanogaster the archetypal Runx protein, Runt, functions in numerous processes including segmentation, neurogenesis and sex determination. During primary sex determination Runt acts as one of four X-linked signal element (XSE) proteins that direct female-specific activation of the establishmen promoter (Pe) of the master regulatory gene Sex-lethal (Sxl). Successful activation of SxlPe requires that the XSE proteins overcome the repressive effects of maternally deposited Groucho (Gro), a potent co-repressor of the Gro/TLE family. Runx proteins, including Runt, contain a C-terminal peptide, VWRPY, known to bind to Gro/TLE proteins to mediate transcriptional repression. We show that Runt’s VWRPY co-repressor-interaction domain is needed for Runt to activate SxlPe. Deletion of the Gro-interaction domain eliminates Runt-ability to activate SxlPe, whereas replacement with a higher affinity, VWRPW, sequence promotes Runt-mediated transcription. This suggest that Runt activates SxlPe by antagonizing Gro function, a conclusion consist with earlier findings that Runt is needed for Sxl expression only in embryonic regions with high Gro activity. Surprisingly we found that Runt is not required for the initial activation activation of SxlPe. Instead, Runt is needed to keep SxlPe active during the subsequent period of high-level Sxl transcription suggesting that Runt helps amplfy the difference between female and male XSE signals by counterrepressing Gro in female, but not in male, embryos.

A Theoretical Model for the Regulation of Sex-lethal, a Gene That Controls Sex Determination and Dosage Compensation in Drosophila melanogaster

Genetics ◽  
2003 ◽  
Vol 165 (3) ◽  
pp. 1355-1384
Author(s):  
Matthieu Louis ◽  
Liisa Holm ◽  
Lucas Sánchez ◽  
Marcelle Kaufman
Keyword(s):  
Drosophila Melanogaster ◽  
Theoretical Model ◽  
Sex Determination ◽  
Numerical Simulations ◽  
Cell Fate ◽  
Regulatory Gene ◽  
Experimental Studies ◽  
Formal Basis ◽  
Sex Lethal ◽  
Specific Regulation

Abstract Cell fate commitment relies upon making a choice between different developmental pathways and subsequently remembering that choice. Experimental studies have thoroughly investigated this central theme in biology for sex determination. In the somatic cells of Drosophila melanogaster, Sex-lethal (Sxl) is the master regulatory gene that specifies sexual identity. We have developed a theoretical model for the initial sex-specific regulation of Sxl expression. The model is based on the well-documented molecular details of the system and uses a stochastic formulation of transcription. Numerical simulations allow quantitative assessment of the role of different regulatory mechanisms in achieving a robust switch. We establish on a formal basis that the autoregulatory loop involved in the alternative splicing of Sxl primary transcripts generates an all-or-none bistable behavior and constitutes an efficient stabilization and memorization device. The model indicates that production of a small amount of early Sxl proteins leaves the autoregulatory loop in its off state. Numerical simulations of mutant genotypes enable us to reproduce and explain the phenotypic effects of perturbations induced in the dosage of genes whose products participate in the early Sxl promoter activation.

scholarly journals Rapid transcriptional regulation by phytochrome of the genes for phytochrome and chlorophyll a/b-binding protein in Avena sativa.

1988 ◽  
Vol 8 (11) ◽  
pp. 4840-4850 ◽  
Author(s):  
J L Lissemore ◽  
P H Quail
Keyword(s):  
Signal Transduction ◽  
Chlorophyll A ◽  
Transcriptional Repression ◽  
Binding Protein ◽  
Regulatory Gene ◽  
Active Form ◽  
Signal Transduction Pathway ◽  
Direct Control ◽  
High Level ◽  
Concurrent Analysis

We have examined phytochrome-regulated transcription of phytochrome (phy) and chlorophyll a/b binding protein (cab) genes in dark-grown Avena seedlings by using run-on transcription in isolated nuclei. Kinetic analysis of phy transcription following pulse-light treatments to produce various amounts of Pfr, the active form of phytochrome, leads to these conclusions. (i) Transcription decreases rapidly (discernible within 5 min) after Pfr formation, reaching an essentially undetectable level by 1 h. (ii) The response is very sensitive; less than 1% Pfr is sufficient to produce maximum feedback repression over the first 30 min. (iii) The duration of transcriptional repression is proportional to the Pfr concentration; derepression begins once the concentration falls below some saturation level because of degradation of Pfr. Concurrent analysis of cab transcription leads to these conclusions. (i) After Pfr formation, transcription increases approximately 10-fold by 3 h, but this response is not detectable until after a 30-min lag. (ii) Detectable induction of cab requires a greater than 30-fold-higher Pfr level than is needed to repress phy expression. (iii) Transcription returns to the preirradiation level considerably sooner than does phy transcription (less than 12 h versus greater than 24 h respectively), indicating that a high level of Pfr is needed to sustain the increased transcription of cab. Taken together, these results suggest that differences in the phytochrome signal transduction pathway are responsible for the distinct patterns of regulation of these genes. Full repression of phy occurs even when protein synthesis is inhibited greater than 90% by cycloheximide and chloramphenicol. In conjunction with the rapidity of the response to Pfr, this result provides evidence that feedback repression of phy gene transcription does not require expression of an intervening regulatory gene(s). Thus, phy is the first gene for which there is evidence for direct control of transcription by the phytochrome signal transduction chain.

Rapid transcriptional regulation by phytochrome of the genes for phytochrome and chlorophyll a/b-binding protein in Avena sativa

1988 ◽  
Vol 8 (11) ◽  
pp. 4840-4850
Author(s):  
J L Lissemore ◽  
P H Quail
Keyword(s):  
Signal Transduction ◽  
Chlorophyll A ◽  
Transcriptional Repression ◽  
Binding Protein ◽  
Regulatory Gene ◽  
Active Form ◽  
Signal Transduction Pathway ◽  
Direct Control ◽  
High Level ◽  
Concurrent Analysis

We have examined phytochrome-regulated transcription of phytochrome (phy) and chlorophyll a/b binding protein (cab) genes in dark-grown Avena seedlings by using run-on transcription in isolated nuclei. Kinetic analysis of phy transcription following pulse-light treatments to produce various amounts of Pfr, the active form of phytochrome, leads to these conclusions. (i) Transcription decreases rapidly (discernible within 5 min) after Pfr formation, reaching an essentially undetectable level by 1 h. (ii) The response is very sensitive; less than 1% Pfr is sufficient to produce maximum feedback repression over the first 30 min. (iii) The duration of transcriptional repression is proportional to the Pfr concentration; derepression begins once the concentration falls below some saturation level because of degradation of Pfr. Concurrent analysis of cab transcription leads to these conclusions. (i) After Pfr formation, transcription increases approximately 10-fold by 3 h, but this response is not detectable until after a 30-min lag. (ii) Detectable induction of cab requires a greater than 30-fold-higher Pfr level than is needed to repress phy expression. (iii) Transcription returns to the preirradiation level considerably sooner than does phy transcription (less than 12 h versus greater than 24 h respectively), indicating that a high level of Pfr is needed to sustain the increased transcription of cab. Taken together, these results suggest that differences in the phytochrome signal transduction pathway are responsible for the distinct patterns of regulation of these genes. Full repression of phy occurs even when protein synthesis is inhibited greater than 90% by cycloheximide and chloramphenicol. In conjunction with the rapidity of the response to Pfr, this result provides evidence that feedback repression of phy gene transcription does not require expression of an intervening regulatory gene(s). Thus, phy is the first gene for which there is evidence for direct control of transcription by the phytochrome signal transduction chain.

scholarly journals Pits and CtBP Control Tissue Growth in Drosophila melanogaster with the Hippo Pathway Transcription Repressor Tgi

Genetics ◽  
2020 ◽  
Vol 215 (1) ◽  
pp. 117-128
Author(s):  
Joseph H. A. Vissers ◽  
Lucas G. Dent ◽  
Colin M. House ◽  
Shu Kondo ◽  
Kieran F. Harvey
Keyword(s):  
Drosophila Melanogaster ◽  
Cell Fate ◽  
Transcriptional Repression ◽  
Target Genes ◽  
Affinity Purification ◽  
Hippo Pathway ◽  
Tissue Growth ◽  
Organ Size ◽  
Link Type ◽  
The Hippo Pathway

The Hippo pathway is an evolutionarily conserved signaling network that regulates organ size, cell fate, and tumorigenesis. In the context of organ size control, the pathway incorporates a large variety of cellular cues, such as cell polarity and adhesion, into an integrated transcriptional response. The central Hippo signaling effector is the transcriptional coactivator Yorkie, which controls gene expression in partnership with different transcription factors, most notably Scalloped. When it is not activated by Yorkie, Scalloped can act as a repressor of transcription, at least in part due to its interaction with the corepressor protein Tgi. The mechanism by which Tgi represses transcription is incompletely understood, and therefore we sought to identify proteins that potentially operate together with Tgi. Using an affinity purification and mass-spectrometry approach we identified Pits and CtBP as Tgi-interacting proteins, both of which have been linked to transcriptional repression. Both Pits and CtBP were required for Tgi to suppress the growth of the Drosophila melanogaster eye and CtBP loss suppressed the undergrowth of yorkie mutant eye tissue. Furthermore, as reported previously for Tgi, overexpression of Pits repressed transcription of Hippo pathway target genes. These findings suggest that Tgi might operate together with Pits and CtBP to repress transcription of genes that normally promote tissue growth. The human orthologs of Tgi, CtBP, and Pits (VGLL4, CTBP2, and IRF2BP2) have previously been shown to physically and functionally interact to control transcription, implying that the mechanism by which these proteins control transcriptional repression is conserved throughout evolution.

scholarly journals Heterochromatic Stellate Gene Cluster in Drosophila melanogaster: Structure and Molecular Evolution

Genetics ◽  
1997 ◽  
Vol 146 (1) ◽  
pp. 253-262 ◽  
Author(s):  
Alexei V Tulin ◽  
Galina L Kogan ◽  
Dominik Filipp ◽  
Maria D Balakireva ◽  
Vladimir A Gvozdev
Keyword(s):  
Drosophila Melanogaster ◽  
Molecular Evolution ◽  
Protein Kinase Ck2 ◽  
Unknown Origin ◽  
Open Reading Frames ◽  
Β Subunit ◽  
Retrotransposon Insertion ◽  
High Level ◽  
Kinase Ck2 ◽  
Reading Frames

The 30-kb cluster comprising close to 20 copies of tandemly repeated Stellate genes was localized in the distal heterochromatin of the X chromosome. Of 10 sequenced genes, nine contain undamaged open reading frames with extensive similarity to protein kinase CK2 β-subunit; one gene is interrupted by an insertion. The heterochromatic array of Stellate repeats is divided into three regions by a 4.5-kb DNA segment of unknown origin and a retrotransposon insertion: the A region (∼14 Stellate genes), the adjacent B region (approximately three Stellate genes), and the C region (about four Stellate genes). The sequencing of Stellate copies located along the discontinuous cluster revealed a complex pattern of diversification. The lowest level of divergence was detected in nearby Stellate repeats. The marginal copies of the A region, truncated or interrupted by an insertion, escaped homogenization and demonstrated high levels of divergence. Comparison of copies in the B and C regions, which are separated by a retrotransposon insertion, revealed a high level of diversification. These observations suggest that homogenization takes place in the Stellate cluster, but that inserted sequences may impede this process.

scholarly journals A GENETICALLY DISTINCT FORM OF CYCLIC AMP PHOSPHODIESTERASE ASSOCIATED WITH CHROMOMERE 3D4 IN DROSOPHILA MELANOGASTER

Genetics ◽  
1979 ◽  
Vol 91 (3) ◽  
pp. 521-535
Author(s):  
John A Kiger ◽  
Eric Golanty
Keyword(s):  
Drosophila Melanogaster ◽  
Cyclic Amp ◽  
Structural Gene ◽  
Regulatory Gene ◽  
Heat Stability ◽  
Normal Female ◽  
Dependent Manner ◽  
Cyclic Amp Phosphodiesterase ◽  
Heat Stable ◽  
Camp Levels

ABSTRACT Two cyclic AMP phosphodiesterase enzymes (E.C.3.1.4.17) are present in homogenates of adult Drosophila melanogaster. The two enzymes differ from one another in heat stability, affinity for Mg++, Ca++ activation and molecular weight. They do not differ markedly in their affinities for cyclic AMP, and both exhibit anomalous Michaelis-Menten kinetics. The more heatlabile enzyme is controlled in a dosage-dependent manner by chromomere 3D4 of the X chromosome and is absent in flies that are deficient for chromomere 3D4. Chromomere 3D4 is also necessary for the maintenance of normal cAMP levels, for male fertility, and for normal female fertility and oogenesis. The structural gene(s) for the more heat-stable enzyme is located outside of chromomeres 3C12-3D4. Whether 3D4 contains a structural gene, or a regulatory gene necessary for the presence of the labile enzyme, remains to be determined.

scholarly journals In Vivo and In Vitro Assays Evaluating the Biological Activity of Taurine, Glucose and Energetic Beverages

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2198
Author(s):  
Marcos Mateo-Fernández ◽  
Fernando Valenzuela-Gómez ◽  
Rafael Font ◽  
Mercedes Del Río-Celestino ◽  
Tania Merinas-Amo ◽  
...  
Keyword(s):  
Dna Damage ◽  
Drosophila Melanogaster ◽  
Biological Activity ◽  
Biological Effects ◽  
Methylation Status ◽  
Repetitive Sequences ◽  
Energy Drinks ◽  
Red Bull

Taurine is one of the main ingredients used in energy drinks which are highly consumed in adolescents for their sugary taste and stimulating effect. With energy drinks becoming a worldwide phenomenon, the biological effects of these beverages must be evaluated in order to fully comprehend the potential impact of these products on the health due to the fact nutrition is closely related to science since the population consumes food to prevent certain diseases. Therefore, the aim of this study was to evaluate the biological effects of taurine, glucose, classic Red Bull® and sugar-free Red Bull® in order to check the food safety and the nutraceutical potential of these compounds, characterising different endpoints: (i) Toxicology, antitoxicology, genotoxicology and life expectancy assays were performed in the Drosophila melanogaster model organism; (ii) The in vitro chemopreventive activity of testing compounds was determined by assessing their cytotoxicity, the proapoptotic DNA-damage capability to induce internucleosomal fragmentation, the strand breaks activity and the modulator role on the methylation status of genomic repetitive sequences of HL-60 promyelocytic cells. Whereas none tested compounds showed toxic or genotoxic effect, all tested compounds exerted antitoxic and antigenotoxic activity in Drosophila. Glucose, classic Red Bull® and sugar-free Red Bull® were cytotoxic in HL-60 cell line. Classic Red Bull® induced DNA internucleosomal fragmentation although none of them exhibited DNA damage on human leukaemia cells. In conclusion, the tested compounds are safe on Drosophila melanogaster and classic Red Bull® could overall possess nutraceutical potential in the in vivo and in vitro model used in this study. Besides, taurine could holistically be one of the bioactive compounds responsible for the biological activity of classic Red Bull®.

scholarly journals Extended Reproductive Roles of the fruitless Gene in Drosophila melanogaster Revealed by Behavioral Analysis of New fru Mutants

Genetics ◽  
1997 ◽  
Vol 147 (3) ◽  
pp. 1107-1130 ◽  
Author(s):  
Adriana Villella ◽  
Donald A Gailey ◽  
Barbra Berwald ◽  
Saiyou Ohshima ◽  
Phillip T Barnes ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Sex Determination ◽  
Molecular Genetics ◽  
Behavioral Analysis ◽  
Behavioral Phenotypes ◽  
New Mutations

The fruitless mutants fru3 and fru4 were assessed for sex-specific reproductive-behavioral phenotypes and compared to the previously reported fru mutants. Among the several behavioral anomalies exhibited by males expressing these relatively new mutations, some are unique. fru3 and fru4 males are less stimulated to court females than and fru1 and fru2. No courtship pulse song is generated by either fru3 or fru4 males, even though they perform brief wing extensions. fru3 and fru4 males display significantly less chaining behavior than do fru1 males. The hierarchy of courtship responses by fru males directed toward females vs. males, when presented with both sexes simultaneously, is that fru1 males perform vigorous and indiscriminant courtship directed at either sex; fru4 males are similarly indiscriminant, but courtship levels were lower than fru1; fru2 males prefer females; fru3 males show a courtship bias toward males. fru3 and fru4 males essentially lack the Muscle of Lawrence (MOL). On several reproductive criteria, there was no difference between fru-variant females and fru  +. The increases in phenotypic severity measured for the new mutants are discussed in the context of the emerging molecular genetics of fru and with regard to the gene's position within the sex-determination pathway.

The Calorimetric-respirometric Ratio: Its Potential as a Cytotoxicity Test

1994 ◽  
Vol 22 (5) ◽  
pp. 364-376
Author(s):  
Richard B. Kemp ◽  
Catherine Stephansen ◽  
Sajid Mohamed ◽  
R.W. John Meredith
Keyword(s):  
Heat Flux ◽  
Salt Solution ◽  
Krebs Cycle ◽  
Cytotoxicity Test ◽  
Antimycin A ◽  
Rich Medium ◽  
Animal Cells ◽  
Normal Input ◽  
High Level ◽  
L929 Mouse

The ratio between heat flux and oxygen flux, the calorimetric ratio, is an enthalpy budget device used to identify anaerobic pathways in the presence of respiration. Ratios that are more exothermic (i.e. more negative) than the average for catabolic substrates (-450kJ mol O2 ± 5%; Thornton's rule), are usual for cells established in culture, including suspension-adapted LS-L929 mouse fibroblasts. A common reason for this is a high level of glycolysis, to produce lactate, simultaneously with aerobic pathways. To test the idea that the calorimetric-respirometric (CR) ratio is a revealing cytotoxic endpoint, LS cells grown in serum-rich medium were insulted with known metabolic poisons. Malonate, 2,4-dinitrophenol (2,4-DNP) and a mixture of antimycin A and rotenone increased the CR ratio to degrees largely explained by greater lactate flux, the CR700 values being 22μM malonate, 56μM 2,4-DNP and, for the mixture, 2μM antimycin A and 5μM rotenone. Higher concentrations of 2,4-DNP gave an “exothermic gap” for which there was no explained pathway. Iodoacetate decreased the CR ratio while inhibiting glycolysis, a result which can be explained by the hypothesis that substrates available in the serum were degraded by mitochondrial pathways and thereby substituted for the normal input from the Krebs cycle, which had been arrested by pyruvate starvation. In a balanced salt solution containing only 5.5mM glucose, the metabolic rate slowed and the CR ratio was more exothermic (CR700 = 6μM), giving a “gap” for which there was no explanation. Ten MEIC chemicals gave CR700 endpoints which closely corresponded to the order of toxicity for a battery of tests using animal cells. The CR method thus provides a good basis for investigating the mechanisms by which chemicals have toxic effects on cells.

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