Transcriptional quiescence in primordial germ cells.

In most animal species, newly formed primordial germ cells (PGCs) acquire the special characteristics that distinguish them from the surrounding somatic cells. Proper fate specification of the PGCs is coupled with transcriptional quiescence, whether they are segregated by determinative or inductive mechanisms. Inappropriate differentiation of PGCs into somatic cells is thought to be prevented due to repression of RNA polymerase (Pol) II-dependent transcription.

The role of SAGA coactivator complex in snRNA transcription.

The general snRNA gene transcription apparatus has been extensively studied. However, the role of coactivators in this process is far from being clearly understood. Here, we have demonstrated that the Drosophila SAGA complex interacts with the PBP complex, the key component of the snRNA gene transcription apparatus, and is present at the promoter regions of the snRNA genes transcribed by both the RNA polymerase II and RNA polymerase III (U6 snRNA).

5-hydroxymethylcytosine in DNA repair: A new player or a red herring?

Active DNA demethylation performed by ten-eleven translocation (TET) enzymes produces 5-hydroxymethylcytosines, 5-formylcytosines, and 5-carboxylcytosines. Recent observations suggest that 5-hydroxymethylcytosine is a stable epigenetic mark rather than merely an intermediate of DNA demethylation. However, the clear functional role of this new epigenetic player is elusive.

Unraveling the mechanisms of chromatin fibril packaging.

Recent data indicate that eukaryotic chromosomes are organized into Topologically Associating Domains (TADs); however, the mechanisms underlying TAD formation remain obscure. Based on the results of Hi-C analysis performed on 4 Drosophila melanogaster cell lines, we have proposed that specific properties of nucleosomes in active and repressed chromatin play a key role in the formation of TADs. Our computer simulations showed that the ability of "inactive" nucleosomes to stick to each other and the lack of such ability in "active" nucleosomes is sufficient for spatial segregation of these types of chromatin, which is revealed in the Hi-C analysis as TAD/inter-TAD partitioning.

Topologically-associating domains: gene warehouses adapted to serve transcriptional regulation.

Structural-functional domains have long been hypothesized to occur in eukaryotic chromosomes, but their existence still remains controversial. Here, we discuss the current state of studies of 3D genome folding and the relation of this folding to the functional organization of the genome.

Early S-phase cell hypersensitivity to heat stress.

Heat stress is one of the best-studied exogenous stress factors; however little is known about its delayed effects. Recently, we have shown that heat stress induces cellular senescence-like G2 arrest exclusively in early S-phase cells. The mechanism of this arrest includes the generation of heat stress-induced single-stranded DNA breaks, the collision of replication forks with these breaks and the formation of difficult-to-repair double-stranded DNA breaks.

A new role for PGRP-S (Tag7) in immune defense: lymphocyte migration is induced by a chemoattractant complex of Tag7 with Mts1.

PGRP-S (Tag7) is an innate immunity protein involved in the antimicrobial defense systems, both in insects and in mammals. We have previously shown that Tag7 specifically interacts with several proteins, including Hsp70 and the calcium binding protein S100A4 (Mts1), providing a number of novel cellular functions. Here we show that Tag7-Mts1 complex causes chemotactic migration of lymphocytes, with NK cells being a preferred target.

Identification of structural DNA variations in human cell cultures after long-term passage.

Random amplified polymorphic DNA (RAPD) analysis was adapted for genomic identification of cell cultures and evaluation of DNA stability in cells of different origin at different culture passages. DNA stability was observed in cultures after no more than 5 passages. Adipose-derived stromal cells demonstrated increased DNA instability.