scholarly journals Corepressive Action of CBP on Androgen Receptor Transactivation in Pericentric Heterochromatin in a Drosophila Experimental Model System

2008 ◽  
Vol 29 (4) ◽  
pp. 1017-1034 ◽  
Author(s):  
Yue Zhao ◽  
Ken-ichi Takeyama ◽  
Shun Sawatsubashi ◽  
Saya Ito ◽  
Eriko Suzuki ◽  
...  
Keyword(s):  
Androgen Receptor ◽  
Experimental Model ◽  
Mammalian Cells ◽  
Target Genes ◽  
Position Effect ◽  
Pericentric Heterochromatin ◽  
Model System ◽  
Position Effect Variegation ◽  
Creb Binding Protein ◽  
Experimental Model System

ABSTRACT Ligand-bound nuclear receptors (NR) activate transcription of the target genes. This activation is coupled with histone modifications and chromatin remodeling through the function of various coregulators. However, the nature of the dependence of a NR coregulator action on the presence of the chromatin environment at the target genes is unclear. To address this issue, we have developed a modified position effect variegation experimental model system that includes an androgen-dependent reporter transgene inserted into either a pericentric heterochromatin region or a euchromatic region of Drosophila chromosome. Human androgen receptor (AR) and its constitutively active truncation mutant (AR AF-1) were transcriptionally functional in both chromosomal regions. Predictably, the level of AR-induced transactivation was lower in the pericentric heterochromatin. In genetic screening for AR AF-1 coregulators, Drosophila CREB binding protein (dCBP) was found to corepress AR transactivation at the pericentric region whereas it led to coactivation in the euchromatic area. Mutations of Sir2 acetylation sites or deletion of the CBP acetyltransferase domain abrogated dCBP corepressive action for AR at heterochromatic areas in vivo. Such a CBP corepressor function for AR was observed in the transcriptionally silent promoter of an AR target gene in cultured mammalian cells. Thus, our findings suggest that the action of NR coregulators may depend on the state of chromatin at the target loci.

Wheat regenerants in the system of rapid assessment of the effect of 24-epibrassinolide

Biomics ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 394-397
Author(s):  
Seldimirova O.A. ◽  
M.V. Bezrukova ◽  
N.N. Кruglova ◽  
F.М. Shakirova
Keyword(s):  
Plant Growth ◽  
Experimental Model ◽  
Plant Growth Regulators ◽  
Growth Regulators ◽  
Drought Resistance ◽  
Rapid Assessment ◽  
Immature Embryo ◽  
Model System ◽  
Wheat Cultivars ◽  
Experimental Model System

The influence of 24-epibrassinolide on the efficiency of regenerants obtained from embryonic calli formation was studied in wheat cultivars contrast for drought resistance. The possibility of using the experimental model system «immature embryo – embryonic callus – regenerant» in the rapid assessment of the effect of antistress plant growth regulators is shown.

white+ Transgene Insertions Presenting a Dorsal/Ventral Pattern Define a Single Cluster of Homeobox Genes That Is Silenced by the Polycomb-group Proteins in Drosophila melanogaster

Genetics ◽  
1998 ◽  
Vol 149 (1) ◽  
pp. 257-275 ◽  
Author(s):  
Sophie Netter ◽  
Marie-Odile Fauvarque ◽  
Ruth Diez del Corral ◽  
Jean-Maurice Dura ◽  
Dario Coen
Keyword(s):  
Chromatin Structure ◽  
Target Genes ◽  
Position Effect ◽  
Phenotypic Expression ◽  
Positional Information ◽  
Genomic Region ◽  
Polycomb Group ◽  
Position Effect Variegation ◽  
Trithorax Group ◽  
Clear Cut

AbstractWe used the white gene as an enhancer trap and reporter of chromatin structure. We collected white+ transgene insertions presenting a peculiar pigmentation pattern in the eye: white expression is restricted to the dorsal half of the eye, with a clear-cut dorsal/ventral (D/V) border. This D/V pattern is stable and heritable, indicating that phenotypic expression of the white reporter reflects positional information in the developing eye. Localization of these transgenes led us to identify a unique genomic region encompassing 140 kb in 69D1–3 subject to this D/V effect. This region contains at least three closely related homeobox-containing genes that are constituents of the iroquois complex (IRO-C). IRO-C genes are coordinately regulated and implicated in similar developmental processes. Expression of these genes in the eye is regulated by the products of the Polycomb -group (Pc-G) and trithorax-group (trx-G) genes but is not modified by classical modifiers of position-effect variegation. Our results, together with the report of a Pc -G binding site in 69D, suggest that we have identified a novel cluster of target genes for the Pc-G and trx-G products. We thus propose that ventral silencing of the whole IRO-C in the eye occurs at the level of chromatin structure in a manner similar to that of the homeotic gene complexes, perhaps by local compaction of the region into a heterochromatin-like structure involving the Pc-G products.

The Additional sex combs gene of Drosophila encodes a chromatin protein that binds to shared and unique Polycomb group sites on polytene chromosomes

Development ◽  
1998 ◽  
Vol 125 (7) ◽  
pp. 1207-1216 ◽  
Author(s):  
D.A. Sinclair ◽  
T.A. Milne ◽  
J.W. Hodgson ◽  
J. Shellard ◽  
C.A. Salinas ◽  
...  
Keyword(s):  
Target Genes ◽  
Position Effect ◽  
Polytene Chromosomes ◽  
Polycomb Group ◽  
Position Effect Variegation ◽  
Sex Combs ◽  
Effect Variegation ◽  
The Central Nervous System ◽  
Additional Sex Combs ◽  
Site Recognition

The Additional sex combs (Asx) gene of Drosophila is a member of the Polycomb group of genes, which are required for maintenance of stable repression of homeotic and other loci. Asx is unusual among the Polycomb group because: (1) one Asx allele exhibits both anterior and posterior transformations; (2) Asx mutations enhance anterior transformations of trx mutations; (3) Asx mutations exhibit segmentation phenotypes in addition to homeotic phenotypes; (4) Asx is an Enhancer of position-effect variegation and (5) Asx displays tissue-specific derepression of target genes. Asx was cloned by transposon tagging and encodes a protein of 1668 amino acids containing an unusual cysteine cluster at the carboxy terminus. The protein is ubiquitously expressed during development. We show that Asx is required in the central nervous system to regulate Ultrabithorax. ASX binds to multiple sites on polytene chromosomes, 70% of which overlap those of Polycomb, polyhomeotic and Polycomblike, and 30% of which are unique. The differences in target site recognition may account for some of the differences in Asx phenotypes relative to other members of the Polycomb group.

scholarly journals An Experimental-Numerical Investigation on the Effects of Macroporous Scaffold Geometry on Cell Culture Parameters

2017 ◽  
Vol 40 (4) ◽  
pp. 185-195 ◽  
Author(s):  
Hadis Eghbali ◽  
Michele M. Nava ◽  
Gabriella Leonardi ◽  
Davod Mohebbi-Kalhori ◽  
Roberto Sebastiano ◽  
...  
Keyword(s):  
Mass Transport ◽  
Experimental Model ◽  
Model System ◽  
Seeding Density ◽  
Specific Cell ◽  
Waste Products ◽  
Human Osteosarcoma Cells ◽  
Culture Parameters ◽  
Static Conditions ◽  
Experimental Model System

Introduction Perfused bioreactors have been demonstrated to be effective in the delivery of nutrients and in the removal of waste products to and from the interior of cell-populated three-dimensional scaffolds. In this paper, a perfused bioreactor hosting a macroporous scaffold provided with a channel is used to investigate transport phenomena and culture parameters on cell growth. Methods MG63 human osteosarcoma cells were seeded on macroporous poly(ε-caprolactone) scaffolds provided with a channel. The scaffolds were cultured in a perfused bioreactor and in static conditions for 5 days. Cell viability and growth were assessed while the concentration of oxygen, glucose and lactate were measured. An in silico, multiphysics, numerical model was set up to study the fluid dynamics and the mass transport of the nutrients in the perfused bioreactor hosting different scaffold geometries. Results The experimental and numerical results indicated that the specific cell metabolic activity in scaffolds cultured under perfusion was 30% greater than scaffolds cultured under static conditions. In addition, the scaffold provided with a channel enabled the shear stress to be controlled, the initial seeding density to be retained, and adequate mass transport and waste removal. Conclusions We show that the macroporous scaffold provided with a channel cultured in a macroscale bioreactor can be a robust reference experimental model system to systematically investigate and assess crucial culture parameters. We also show that such an experimental model system can be employed as a simplified “representative unit” to improve the performance of both perfused culture systems and hollow, fiber-integrated scaffolds for large-scale tissue engineering.

scholarly journals A Motif within SET-Domain Proteins Binds Single-Stranded Nucleic Acids and Transcribed and Supercoiled DNAs and Can Interfere with Assembly of Nucleosomes

2005 ◽  
Vol 25 (5) ◽  
pp. 1891-1899 ◽  
Author(s):  
Wladyslaw A. Krajewski ◽  
Tatsuya Nakamura ◽  
Alexander Mazo ◽  
Eli Canaani
Keyword(s):  
Nucleic Acids ◽  
Target Genes ◽  
Binding Capacity ◽  
Position Effect ◽  
In Vitro Transcription ◽  
Position Effect Variegation ◽  
Nucleosome Assembly ◽  
Set Domain ◽  
Eukaryotic Chromatin

ABSTRACT The evolutionary conserved SET domain is present in many eukaryotic chromatin-associated proteins, including some members of the trithorax (TrxG) group and the polycomb (PcG) group of epigenetic transcriptional regulators and modifiers of position effect variegation. All SET domains examined exhibited histone lysine methyltransferase activity, implicating these proteins in the generation of epigenetic marks. However, the mode of the initial recruitment of SET proteins to target genes and the way that their association with the genes is maintained after replication are not known. We found that SET-containing proteins of the SET1 and SET2 families contain motifs in the pre-SET region or at the pre-SET-SET and SET-post-SET boundaries which very tightly bind single-stranded DNA (ssDNA) and RNA. These motifs also bind stretches of ssDNA generated by superhelical tension or during the in vitro transcription of duplex DNA. Importantly, such binding withstands nucleosome assembly, interfering with the formation of regular nucleosomal arrays. Two representatives of the SUV39 SET family, SU(VAR)3-9 and G9a, did not bind ssDNA. The trx Z11 homeotic point mutation, which is located within TRX SET and disrupts embryonic development, impairs the ssDNA binding capacity of the protein. We suggest that the motifs described here may be directly involved in the biological function(s) of SET-containing proteins. The binding of single-stranded nucleic acids might play a role in the initial recruitment of the proteins to target genes, in the maintenance of their association after DNA replication, or in sustaining DNA stretches in a single-stranded configuration to allow for continuous transcription.

Sign in / Sign up

Export Citation Format

Share Document