Peculiarities of the molecular composition of heterochromatin associated with pronucleoli in mouse embryos

The nucleus of pre-implantation mammalian embryos is characterized by peculiar structural organization. At the initial stages of cleavage, the nucleus of the embryo contains the so-called nucleolus precursor bodies (NPBs) or pronucleoli rather than functionally active nucleoli. The NPBs are fibrillar electron-dense structures inactive in RNA synthesis. The vast majority of NPBs are surrounded by a ring-shaped zone of transcriptionally inactive heterochromatin. Intriguingly, these zones contain not only tri-methylated histone Н3K9me3 as an epigenetic mark of repressed chromatin but also acetylated histone H4K5ac, a well-known marker of active chromatin. Immunocytochemical data suggest that the molecular composition of this ‘ring heterochromatin’ in mouse embryos changes during the realization of embryonic genome activation events, as well as during artificial suppression of transcription. In zygotes, some factors of mRNA biogenesis including splicing factor SC35 (SRSF2) and basal transcription factor TFIID are detectable in the ring chromatin. At later stages of development, other nuclear proteins such as Y14, a core component of the exon-exon junction complex (EJC), as well as the proteins involved in chromatin remodeling (ATRX, Daxx) are also detectable in this area. A typical component of the ‘ring heterochromatin’ is actin. Anti-actin immunocytochemical labeling is most expressed at the two-cell cleavage stage after activation of the embryonic genome. Indicatively, the molecular composition of the ‘ring heterochromatin’ associated with different NPBs may differ significantly even in the same nucleus. This seems to reflect the functional heterogeneity of morphologically similar NPBs according to their competence to the process of nucleologenesis. Here, we discuss briefly some peculiarities of the molecular composition and possible functions of the NPB-associated heterochromatin in mouse early embryos

A look at new therapeutic opportunities in patients with non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease worldwide, and is considered to be the liver manifestation of metabolic syndrome. Currently, there is no etiotropic treatment of NAFLD, so an active research for new methods of treatment is underway. In the meantime, drugs are used to treat comorbid conditions, such as dyslipidemia, arterial hypertension, obesity, type 2 diabetes, which are present in varying degrees in patients. This review considers medications that are used in patients with NAFLD and related concomitant features, and also describes new strategies for regressing changes in liver tissue in NAFLD. In our opinion, one of the promising groups of drugs are agonists of the farnesoid X receptor (FXR). FXR belongs to the group of nuclear receptors, which are ligand-activated transcription factors that regulate the genes involved in metabolism. FXR agonists can claim to be a new promising drug for the treatment of NAFLD and related diseases influencing carbohydrate metabolism, fat metabolism, bile acid metabolism, as well as inflammatory processes in the liver to ensure metabolic homeostasis

EXPRESSION OF TLR2, TLR3, TLR4 AND PROINFLAMMATORY TNF AND IL-6 CYTOKINES IN LIVER BIOPSIES OF NONALCOHOLIC FATTY LIVER DISEASE PATIENTS

Non-alcoholic fatty liver disease (NAFLD) is a group of conditions closely associated with obesity that are among the most common and socially significant liver diseases in the modern Western world. The emergence and progression of NAFLD from simple steatosis to non-alcoholic steatohepatitis with the subsequent development of fibrosis are the leading factors in the pathogenesis of a significant proportion of the most severe liver pathologies, such as cirrhosis and hepatocellular carcinoma, as well as extrahepatic metabolic complications of NAFLD, such as insulin resistance and type 2 diabetes mellitus. The inflammatory component is one of the most important factors in the pathogenesis of NAFLD, particularly in the context of the progression of simple steatosis to non-alcoholic steatohepatitis. At the same time, the role of the most important mediators of the inflammatory response, innate immunity receptors and the Toll-like receptors in particular, in the pathogenesis of NAFLD has been poorly studied. In the present work, we first used the bioinformatics analysis of the publicly available gene expression databases to demonstrate that only TLR1, TLR2, TLR3 and TLR4 were significantly expressed in the healthy human liver. We then used the reverse transcription PCR to measure the mRNA expression levels of TLR2, TLR3, and TLR4, as well as those of the important pro-inflammatory mediators tumor necrosis factor (TNF) and interleukin-6 (IL-6), in the liver biopsy specimens obtained from 20 patients with NAFLD (simple steatosis, n = 10; non-alcoholic steatohepatitis, n = 10), as well as from 4 obese patients with clinical suspicion for NAFLD but no histological signs of NAFLD in their liver biopsies. We found a significant increase in the expression of TLR2, TLR3 and TLR4 mRNA in liver biopsy samples obtained from patients with non-alcoholic steatohepatitis as compared to those obtained from controls without histological signs of NAFLD. We were also able to demonstrate the association between the hepatic levels of TLR2, TLR3 and TLR4 mRNAs with the histological degree of liver damage as evidenced by the degree of steatosis and balloon dystrophy of hepatocytes, as well as with the plasma levels of uric acid, the important endogenous stimulator of innate immunity. Our data indicate the possible involvement of innate immunity, particularly the Toll-like receptors, in the pathogenesis of NAFLD

mRNA accumulation in the Cajal bodies of the diplotene larch microsporocyte

In microsporocytes of the European larch, we demonstrated the presence of several mRNAs in spherical nuclear bodies. In the nuclei of microsporocytes, we observed up to 12 bodies, ranging from 0.5 to 6 μm in diameter, during the prophase of the first meiotic division. Our previous studies revealed the presence of polyadenylated RNA (poly(A) RNA) in these bodies, but did not confirm the presence of nascent transcripts or splicing factors of the SR family. The lack of these molecules precludes the bodies from being the sites of synthesis and early maturation of primary transcripts (Kołowerzo et al., Protoplasma 236:13–19, 2009). However, the bodies serve as sites for the accumulation of splicing machinery, including the Sm proteins and small nuclear RNAs. Characteristic ultrastructures and the molecular composition of the nuclear bodies, which contain poly(A) RNA, are indicative of Cajal bodies (CBs). Here, we demonstrated the presence of several housekeeping gene transcripts—α-tubulin, pectin methylesterase, peroxidase and catalase, ATPase, and inositol-3-phosphate synthase—in CBs. Additionally, we observed transcripts of the RNA polymerase II subunits RPB2 and RPB10 RNA pol II and the core spliceosome proteins mRNA SmD1, SmD2, and SmE. The co-localization of nascent transcripts and mRNAs indicates that mRNA accumulation/storage, particularly in CBs, occurs in the nucleus of microsporocytes

Nuclear Distribution of RNA Polymerase II and mRNA Processing Machinery in Early Mammalian Embryos

Spatial distribution of components of nuclear metabolism provides a significant impact on regulation of the processes of gene expression. While distribution of the key nuclear antigens and their association with the defined nuclear domains were thoroughly traced in mammalian somatic cells, similar data for the preimplantation embryos are scanty and fragmental. However, the period of cleavage is characterized by the most drastic and dynamic nuclear reorganizations accompanying zygotic gene activation. In this minireview, we try to summarize the results of studies concerning distribution of major factors involved in RNA polymerase II-dependent transcription, pre-mRNA splicing mRNA export that have been carried out on early embryos of mammals

Composition of organic matter from black shales drilled in the Cape Verde Basin in DSDP Hole 41-367

Results of geochemical studies of organic matter in black shales from the Cape Verde Basin are reported. Based on these results, in combination with data of petrographic analysis, conclusions are made about sapropelic nature of their organic matter and low degree of its coalification. It corresponds to the proto-catagenetic substage of sedimentary rocks. Black shales of the Cape Verde Basin are classified as potential oil source strata