[MicroRNA Biogenesis in Cell Senescence Induced by Chronic Endoplasmic Reticulum Stress].

MicroRNAs are small noncoding RNAs that regulate gene expression; stabilize the cell phenotype; and play an important role in cell differentiation, development, and apoptosis. A canonical microRNA biogenesis pathway includes several posttranscriptional steps of processing and transport and ends with cytoplasmic cleavage of pre-miRNA by type III ribonuclease DICER to form a mature duplex, which is included in RISC. MicroRNA biogenesis and role in cell stress are still poorly understood. Using flow cytometry and high-throughput analysis of gene expression, we have shown that chronic endoplasmic reticulum (ER) stress, which is associated with improper protein folding in the ER, induce a cellular senescence phenotype in fibroblast-like FRSN cells. While acute ER stress can reduce miRNA biogenesis, chronic stress does not cause a significant drop in global microRNA expression and is accompanied by only a slight decrease in DICER1 mRNA expression. Heterogeneity with respect to lysosomal ß-galactosidase activity was found to increase in the cell population exposed to ER stress. We do not exclude induced cell heterogeneity regarding expression of components of the microRNA biogenesis pathway.

Comparative analysis of genes encoding key steroid core oxidation enzymes in fast-growing Mycobacterium spp. strains.

A comparative genome analysis of Mycobacterium spp. VKM Ac-1815D, 1816D and 1817D strains used for efficient production of key steroid intermediates (androst-4-ene-3,17-dione, AD, androsta-1,4-diene-3,17-dione, ADD, 9α-hydroxy androst-4-ene-3,17-dione, 9-OH-AD) from phytosterol has been carried out by deep sequencing. The assembled contig sequences were analyzed for the presence putative genes of steroid catabolism pathways. Since 3-ketosteroid-9α-hydroxylases (KSH) and 3-ketosteroid-Δ(1)-dehydrogenase (Δ(1) KSTD) play key role in steroid core oxidation, special attention was paid to the genes encoding these enzymes. At least three genes of Δ(1) KSTD (kstD), five genes of KSH subunit A (kshA), and one gene of KSH subunit B of 3-ketosteroid-9α-hydroxylases (kshB) have been found in Mycobacterium sp. VKM Ac-1817D. Strains of Mycobacterium spp. VKM Ac-1815D and 1816D were found to possess at least one kstD, one kshB and two kshA genes. The assembled genome sequence of Mycobacterium sp. VKM Ac-1817D differs from those of 1815D and 1816D strains, whereas these last two are nearly identical, differing by 13 single nucleotide substitutions (SNPs). One of these SNPs is located in the coding region of a kstD gene and corresponds to an amino acid substitution Lys (135) in 1816D for Ser (135) in 1815D. The findings may be useful for targeted genetic engineering of the biocatalysts for biotechnological application.

Fast detection of MYCN copy number alterations in brain neuronal tumors by real-time PCR.

Increased MYCN gene copy number is a characteristic property of neurogenic tumors. Fluorescence in situ hybridization (FISH) and array-based comparative genomic hybridization (array-CGH) are traditionally used to determine MYCN amplification for tumor stratification. A unique ability of real-time quantitative polymerase chain reaction (qPCR) to determine gene copy number, even within a small percent of observed tumor cells, and can be more appropriate. MYCN genomic copy number from 44 human brain tumors (22 medulloblastomas and 22 neurocytomas) was determined by means of FISH, array-CGH, and qPCR. By qPCR, with the original set of oligonucleotides, 17 out of 44 (38.6%) tumors were found to contain a 1.3- to 2.9-fold increase of MYCN defined as low-level gain. An absolute qPCR method was used to get high accuracy of results. Strong correlation was observed between the three methods: for medulloblastomas, r=1 (P<0.01) between FISH and array-CGH and r=0.92 (P<0.01) between qPCR and FISH/array-CGH. For neurocytomas, r=0.9 (P<0.01) between FISH and array-CGH and r=0.34/0.43 (P<0.01) between qPCR and FISH/array-CGH. Absolute qPCR assays possess high precision compared to other conventional methods and can be used for accurate and quickness detection of MYCN status (low-level gene gain and amplification).

Expression level of lipoprotein lipase and dystrophin genes predict survival in B-cell chronic lymphocytic leukemia.

Mutational status of immunoglobulin variable region genes (VH-genes) is known as the strongest predictor of long term prognosis in B-CLL. However, applications in the routine clinical practice are time consuming, and therefore some other predictions are required. In this study, we have compared prognostic values of real time PCR quantification of the expression levels of four genes previously shown to be differentially expressed in V(H)-unmutated and mutated B-CLL subtypes: ZAP-70, ZBTB20, DMD and LPL. The study included 134 B-CLL patients. Expression levels of LPL and DMD genes were significantly correlated to mutational status, while expression levels of of ZAP-70 gene correlated only in CD19+ selected cases (N = 40). No correlation was observed for ZBTB20 gene. Expression levels of LPL and DMD predicted overall survival in the entire cohort of patients. Prognostic values of LPL gene expression levels were significant even for CLL patients with stage A. Quantitative RT-PCR assays for measuring LPL gene expression are robust enough to be introduced into routine clinical practice.

[Characterization of the universal Russian reagent sets for real-time PCR and its application for molecular oncodiagnostic].

Universal Russian reagents for real time PCR were tested and compared with reference reagents provided by foreign companies. Testing was carried out on plasmids with cloning fragments (DNA-standards) of cDNA with chimeric (fusion) gene PML-RARalpha. Values of amplification efficiency of Russian and foreign reagents were measured on samples with serial dilutions (30-300000 copies) of cloned cDNA fragments of PML-RARalpha and internal control gene ABL. Amplification efficiencies of Russian and foreign reagents were found to be close one to another. Russian universal reagent kit RealityTM and ABI TaqMan Core Reagent Kit have amplification efficiencies 1.919 and 1.929, and correlation coefficients of copy numbers PML-RARalpha0.999 and 0.996, respectively. These values were determined by construction of a standard curve. To verify these results we studied also the samples of cDNA from blood and bone marrow of patients with acute promyelocytic leukemia. All samples posses translocation t(15;17), and appropriate chimeric gene PML-RARalpha. copy number in 1 microg of total RNA was in range 5.86 x 10(4)-8.315 x 10(5) before chemotherapy. No symptoms of minimal residual disease were found after 3.5 months since chemotherapy - fusion gene PML-RARalpha was not detected by real time PCR method. These results are in agreement with clinical data. Our investigations tend to show that application of RealityTM reagent set in real timePCR experiments gives correct results and may be used in molecular oncodiagnostics.