Activation of Su(Hw)-Controlled Genes Is Associated with Increase in GAF Binding.

The interaction of the GAF protein with the promoters of neuron-specific genes during activation and repression of transcription was studied. We showed that, while the Su(Hw) protein remains stably associated with the promoters of these genes at different transcriptional state, the GAF protein level is significantly higher when transcription is activated.

The bxdPRE/TRE element terminates passing through transcription.

The regulation of PRE/TRE activity is required for appropriate tissue and stage-specific gene expression. However, the molecular principles of PRE/TRE activity control remain unknown. Here we show that PRE/TRE element from Ubx regulatory region efficiently terminates passing through transcription.

[Control of the gene activity by polycomb and trithorax group proteins in Drosophila].

Combinatorial expression of the genes in multicellular organisms leads to the development of different cell types. The important epigenetic regulators of higher eukaryotes are the Polycomb group (PcG) and Trithorax group (TrxG) proteins. These factors control the transcription of a large number of genes involved in various cellular processes. Dysregulation of PcG and TrxG systems leads to developmental abnormalities and cancer. This review focuses on the main characteristics and properties of the Drosophila PRE elements. Furthermore, we summarize the information on the protein components of the PcG and TrxG groups and their functional activities and discuss the main aspects of competition between the proteins of these classes as well as their possible mechanisms of action.

Role of Transcriptional Read-Through in PRE Activity in Drosophila melanogaster.

Maintenance of the individual patterns of gene expression in different cell types is required for the differentiation and development of multicellular organisms. Expression of many genes is controlled by Polycomb (PcG) and Trithorax (TrxG) group proteins that act through association with chromatin. PcG/TrxG are assembled on the DNA sequences termed PREs (Polycomb Response Elements), the activity of which can be modulated and switched from repression to activation. In this study, we analyzed the influence of transcriptional read-through on PRE activity switch mediated by the yeast activator GAL4. We show that a transcription terminator inserted between the promoter and PRE doesn't prevent switching of PRE activity from repression to activation. We demonstrate that, independently of PRE orientation, high levels of transcription fail to dislodge PcG/TrxG proteins from PRE in the absence of a terminator. Thus, transcription is not the main factor required for PRE activity switch.

SV40 transcription terminators stabilize the activity of regulatory elements in Drosophila melanogaster.

To ensure stable operation of transgenic systems and maintain reporter gene expression at a certain level, it is necessary to search for the conditions that protect the activity of regulatory elements. In this study, we have shown that the SV40 transcription terminators flanking the transgene protect enhancers and silencers of Drosophila and ensure their efficient functioning.

[The Role of Su(Hw) Protein in Transcription Regulation in Drosophila melanogaster].

Insulators are regulatory DNA elements that modulate the effect of enhancers and silencers on gene transcription. However, the role of the insulator complex proteins in the expression of specific genes remains scarcely studied. In the present study, we examined the role of the Su(Hw)-dependent insulator complex in transcription of the rap, CG32810, and RpS15Aa genes. It was demonstrated that the interaction of Su(Hw) and Mod(mdg4)-67.2 insulator proteins with the terminator regions of the selected genes was dependent on the Su(Hw) factor. At the same time, the CP190 protein also interacts with the promoter and terminator regions in the absence of Su(Hw). In addition, the Su(Hw) protein does not affect the level of transcription and silencing efficiency of the gene models. A possible explanation for these results is the existence of another transcription factor, a protein that is able to recruit CP190 and functionally compensate for the lack of the Su(Hw) protein.

[Interactions of 1A2 insulator with promoter of hsp 70 gene in Drosophila melanogaster].

Insulators are regulatory DNA elements that participate in the modulation of the interactions between enhancers and promoters. Depending on the situation, insulators can either stabilize or destroy the contacts between enhancers and promoters. A possible explanation for the activity of insulators is their ability to directly interact with gene promoters. In the present study, it was demonstrated that, in model systems, a 1A2 insulator could interact with the core sequence of an hsp70 promoter. In this case, the insulator protein CP190 is found on the hsp70 promoter, which depends on the presence of an insulator in the transgene. The data obtained are consistent with the model, which implies that direct contacts between insulators and promoters make a considerable contribution to the modulation of the interactions between insulators and promoters.