[Activation of JAK/STAT signaling pathway in S2 Drosophila melanogaster cell culture].

JAK/STAT signaling pathway plays a critical role in different ontogenesis processes of higher eukaryotes. Fruit fly drosophila is a handy model system used to study this pathway since major components of the pathway are represented by unique factors. This article describes the usage of Drosophila melanogaster S2 cells in studies of the pathway's target genes activation. We showed that S2 cells contain plenty of STAT protein which migrates into nucleus under cells treatment with pervanadate. Then we demonstrated that under pervanadate action STAT protein along with other transcription factors is recruited onto regulatory sequences of target genes and activates their transcription.

[SAYP interacts with DHR3 nuclear receptor and participates in ecdysone-dependent transcription regulation].

The role of metazoan coactivator SAYP in nuclear receptor-driven gene activation in the ecdysone cascade of Drosophila is considered. SAYP interacts with DHR3 nuclear receptor and activates the corresponding genes by recruiting the BTFly (Brahma and TFIID) coactivator supercomplex. The knockdown of SAYP leads to a decrease in the level of DHR3-activated transcription. DHR3 and SAYP interact during development and have multiple common targets across the genome.

[Novel conservative domain of SAYP coactivator mediates TFIID and Brahma transcriptional complexes interaction].

In the S2 cell system of Drosophila melanogaster a key protein domain mediating the interaction of TFIID and Brahma transcriptional complexes into the BTFly supercomplex has been shown to be an evolutionary conserved SAY domain of the SAYP. TFIID and Brahma coactivators participated in the reporter gene activation induced by the SAY domain in cellular nuclei. The TFIID and Brahma components directly interacting with the SAY domain were identified.

[SAYP--a novel regulator of metazoan development].

SAYP is a dual-function transcriptional coactivator of RNA polymerase II. It is a metazoan-specific factor involved in different signaling pathways that control normal development. In Drosophila, SAYP is present in the organism from the early stages of development and participates in cell cycle synchronization at the blastoderm stage. SAYP is abundant in many embryonic cells and in imaginal discs of larvae and is crucial for oogenesis in adults. At the molecular level, SAYP serves as a basis for assembling the BTFly nuclear supercomplex consising of the Brahma and TFIID coactivators. We suppose that BTFly and other similar nuclear supercomplexes play an important role in ontogenesis.

[Conservative E(y)2/Sus1 protein is the member of SAGA complex and new nuclear pore-associated complex in Drosophila].

The SGA/TFTC complex plays an important role in the regulation of transcription. We have examined the significance of the gene positioning in the nucleus for its transcription and subsequent export of nascent mRNA. It was demonstrated that E(y)2 protein was a subunit of the SAGA/TFTC histone acetyl transferase complex in Drosophila and that E(y)2 concentrated at the nuclear periphery. An interaction between E(y)2 and the nuclear pore complex (NPC) was demonstrated, as well as that SAGA/TFTC also contacted the NPC at nuclear periphery. In addition, it was shown that E(y)2 formed complex with the Xmas-2 protein (X-linked male sterile 2) both in normal conditions and after heat shock. Importantly, the E(y)2 and Xmas-2 knockdown decreased the contact between the heat-shock protein 70 (hsp70) gene loci and the nuclear envelope before and after activation, and interfered with the transcription. Thus, E(y)2 and Xmas-2 together with SAGA/TFTC functioned in the anchoring of a subset of transcription sites to the NPCs to achieve efficient transcription and mRNA export.

[Study of the Drosophila melanogaster trf2 gene and its protein product].

The Drosophila melanogaster TRF2 protein regulates transcription of several genes. The trf2 gene structure was studied. The gene proved to code for two protein isoforms, a known 75-kDa isoform and a newly identified 175-kDa isoform. The new isoform combines the known isoform sequence with an extended N end containing a coiled-coil motif. The long TRF2 isoform was found to act as a component of a multiprotein complex, including ISWI ATPase as well.

[Nuclear receptors: structure and mechanisms of action].

Nuclear receptors are a superfamily of conserved transcription factors with a unique domain structure. Nuclear receptors play an important role in the regulation of ontogeny, sexual maturation, and cell differentiation, as well as in various metabolic processes. Owing to the specifics of hormonal signaling, Drosophila melanogaster provides a promising model subject for studying the function and regulation of nuclear receptors. The review considers modem data on the molecular structure of nuclear receptors and the mechanisms of their interactions with ligands and transcription cofactors. The known functions of nuclear receptors in regulating embryo development and metamorphosis in D. melanogaster are described in detail.

[Transcriptional coactivator SAYP can suppress transcription in heterochromatin].

The new transcriptional coactivator SAYP binds at many sites to transcriptionally active chromatin of polytene chromosomes, colocalizes with RNA polymerase II, and coactivates transcription. On the other hand, SAYP is present in heterochromatic regions of chromosome IV and in the chromocenter and suppresses transcription of transgenes located in heterochromatin. The conserved SAY domain of SAYP is involved in transcription activation, while its PHD domains are responsible for gene silencing in heterochromatin. Thus, SAYP plays a dual role in regulating transcription in euchromatic and heterochromatic regions.