Том 10, № 4 (2016)

Although progress has been made in understanding the causes and consequences of genetic and epigenetic changes in glioma malignant transformation, many details remain obscure and need further investigation. It is known that glioma malignant transformation is accompanied by gradual loss of LGI1 gene expression. However, genetic defects underlying LGI1 inactivation are not recognized. In this work, we analyzed LGI1 gene expression in primary cultures of malignant gliomas and compared these data with posttranslational modifications of H3 histone, an epigenetic indicator of transcriptional activity. We showed the presence of an epigenetic marker of gene repression H3K9me3 near LGL1 transcription initiation site in most malignant gliomas (five out of six). No expression of LGI1 gene was registered in these gliomas. LGI1 expression was documented only in one glioma, and this tumor did not exhibit an association of LGI1 gene with H3K9me3 modification. Thus, we demonstrated for the first time a correlation between an LGI1 gene expression and epigenetic indicator H3K9met3 in malignant gliomas. An Н3К4ас marker of actively transcribed chromatin near LGI1 transcription initiation site was not found. These data suggest the inactivation of LGI1 gene through an epigenetic mechanism: a modified “histone code.”

Impaired metabolism of α-synuclein (SNCA) and its aggregation are key molecular events underlying Parkinson’s disease (PD). Emerging data show that there is a connection between PD and the gene locus containing the SNCA gene. Meta-analyses have demonstrated a highly significant PD connection with single nucleotide polymorphisms (SNPs) rs356165 (A/G) and rs356219 (A/G) in the SNCA gene. We conducted SNP genotyping in 260 PD patients (n = 260) and 262 healthy people (n = 262) from northwestern regions of Russia. Linkage disequilibrium was registered between rs356219 and rs356165 alleles (D' = 0.926). It was confirmed that G alleles (rs356165 and rs356219) are associated with increased risk of PD development. For the first time, we have evaluated the relationship between rs356165 and rs356219 and levels of SNCA mRNA and α-synuclein protein in CD45⁺ peripheral blood cells in drug-naïve PD patients (n = 43) and controls (n = 39). Both the level of mRNA SNCA gene and that of α-synuclein protein were increased in carriers of rs356219 and rs356165 compared to carriers with AA genotype in control group (in the group of healthy people) (p = 0.046 and p = 0.039, respectively). Linkage disequilibrium was shown between associated marker alleles. Our data suggest that rs356165 and rs356219 allele variants may affect the PD development by up-regulation of SNCA expression.

UV irradiation is a major natural and artificial stress factor that may cause severe skin injury. UV irradiation induces DNA damage, which, eventually, may lead to cell death, senescence or oncogenic mutations and tumor growth. Wip1 is a phosphatase involved in the regulation of DNA damage response and oncogenic stress. Here, we studied response to UV-B irradiation in wild-type and Wip1-depleted murine cells of epidermal and mesenchymal lineages. We found that both cell types, skin keratinocytes and fibroblasts, responded to UV-B in a similar manner with increased cytotoxicity in Wip1–/–cells. The number of nuclear foci of histone γH2A-X, a DNA damage marker and aWip1 target protein, was higher in Wip1–/–cells before and after UV-B. We observed a twofold increase in cell number with active caspase-3 in Wip1-deficient keratinocytes. Thus, Wip1 deficiency sensitizes cells to UV-B irradiation by promoting cell death, possibly by caspase-3 dependent apoptosis.

The course of infection upon virus entry into the cell depends not only on the biological characteristics of the cells and of the virus itself, but also on the intensity of the cell infection by the virus, i.e., on the multiplicity of infection. The purpose of our work was to perform a comparative study of the responses of two human cell lines, the lung carcinoma cell line A-549 and the endothelium cell line ECV-304, to the infection with the influenza virus A at different multiplicities of infection. At the first passage, both cell lines responded by enhancement of proliferation and apoptosis induction only to the low doses of influenza virus (ID 1–10). In A-49 cells, the stimulatory effect of the low virus doses was observed 1–2 days earlier than in ECV-304 cells. Enhanced proliferation was observed in both cell lines from the second to the fourth passages, when cells were infected with higher virus doses (ID 100 and 1000). In addition, the response of the A-549 cells to low doses of the H3N2 strain of the influenza virus A depended on the virus propagation conditions—namely, no enhancement of cell proliferation was observed in response to the infection with the virus propagating in chicken embryonated eggs, in contrast to infection with the virus that propagated in cell culture. Immunocytochemistry of A-549 cells has demonstrated that, on the third day after infection, there could be observed a change (in the dose-dependent manner) in the intracellular localization of p53 and cyclin A, proteins involved in the cell cycle progression. At the low virus dose, cyclin A was predominantly detected in the nuclei (63%), while at the high virus dose it was p53 (54%), which was predominantly detected in this cellular compartment, this observation confirming that stimulation of cell proliferation in the case of very low multiplicity of infection and cell division arrest takes place in the case of high multiplicity of influenza virus infection. The study of the influenza virus A reproduction in A-549 and ECV-304 cells using a whole number of virology techniques showed low sensitivity of these cells to the influenza virus, which manifested in the gradual decrease in the viral RNA expression and the impairment of mature viral particles assembly during several passages. Therefore, the decrease in the multiplicity of infection is associated in the A-549 and ECV-304 cells with impairment of production of mature virus particles or certain virus protein synthesis, which is accompanied by cell proliferation enhancement and apoptosis induction. As a result of the comparative study of the two cell lines (A-549 and ECV-304) upon infection with different doses of influenza virus A, we have revealed common principles and specific features indicating the effects of the biological properties of the viruses and cells, as well as of the multiplicity of infection on the course of virus infection.

The effect of local anesthetics on the permeability of phospholipid liposomes of different composition for calcein has been investigated. The local anesthetics tested included amides (lidocaine, prilocaine, mepivacaine, and bupivacaine) and esters (benzocaine, procaine, and tetracaine). The permeability of large monolamellar liposomes was assessed by monitoring the fluorescence of calcein leaking from the phospholipid vesicles. All tested amide anesthetics exerted negligible effects on the permeability of dioleylphosphocholine (DOPC) liposomes for the fluorescent marker. The most efficient in this group was did bupivacaine. Amides had a more pronounced effect on membranes in which 20 mol % of DOPC was replaced by tetraoleoylcardiolipin (TOCL). Benzocaine and procaine at concentration up to 100 mM did not affect the permeability of DOPC liposomes. Membrane permeability of DOPC liposomes was not affected by the addition of tetracaine to the final concentration of 2 mM, while the increase of anesthetic concentration up to 50 mM was accompanied by an increase in the intensity of fluorescence of calcein released from the vesicles, and addition of the anesthetic to the concentration of 100 mM caused by complete release of the marker incorporated by the liposomes. The threshold concentration of tetracaine initiating calcein leakage from vesicles that contained 20 mol % TOCL was 7 mM, and the concentration corresponding to 100% calcein leakage was 20 mM. Confocal fluorescence microscopy of giant monolamellar liposomes formed from an equimolar mixture of DOPC and tetramiristoylcardiolipin demonstrated the destruction of solid ordered domains at the presence of anesthetics, and its destructive capacity increasing in the following order: procaine ≈ mepivacaine < bupivacaine ≪ tetracaine. Variability of the depth of anesthetic incorporation into the membrane may account for the dissimilar effects of local anesthetics on liposomes.