Altered gene expression pattern in peripheral blood leukocytes from patients with arterial hypertension

The role of various inflammatory mechanisms and oxidative stress in the development of atherosclerosis and arterial hypertension (AH) has been increasingly acknowledged during recent years. Hypertension per se or factors that cause hypertension along with other complications lead to infiltration of activated leukocytes in the vascular wall, where these cells contribute to the development of vascular injury by releasing cytokines, oxygen radicals, and other toxic mediators. However, molecular mechanisms underlying leukocyte activation at transcriptional level in AH are still far from being clear. To solve this problem we employed cDNA microarray technology to reveal the differences in gene expression in peripheral blood leukocytes from patients with AH compared with healthy individuals. The microarray data were verified by a semi-quantitative RT-PCR method. We found 25 genes with differential expression in leukocytes from AH patients among which 21 genes were upregulated and 4 genes were downregulated. These genes are implicated in apoptosis (CASP2, CASP4, and CASP8, p53, UBID4, NAT1, and Fte-1), inflammatory response (CAGC, CXCR4, and CX3CR1), control of MAP kinase function (PYST1, PAC1, RAF1, and RAFB1), vesicular trafficking of molecules among cellular organelles (GDI-1 and GDI-2), cell redox homeostasis (GLRX), cellular stress (HSPA8 and HSP40), and other processes. Gene expression pattern of the majority of genes was similar in AH patients independent of the disease stage and used hypotensive therapy, but was clearly different from that of normotensive subjects.

Gene expression analysis to identify mRNA markers of cardiac myxoma

cDNA expression arrays were used to identify mRNA expression markers for cardiac myxoma. The RNA profile analysis suggests that cardiac myxoma should be considered as a stand-alone tissue rather than a pathological modification of particular normal tissue. The analysis reveals a set of genes which are highly and steadily expressed in cardiac myxomas and can serve as an mRNA expression markers of the tumour. Marker status of selected genes was confirmed by reverse transcriptase polymerase chain reaction analysis. Genes MIA (melanoma inhibitory activity) and PLA2G2A (phospholipase A2, group IIA) show the highest specificity as cardiac myxoma markers, since they have more than 10-fold higher RNA level in cardiac myxomas than in any one of 15 normal tissues tested. Among markers of myxoma at least three are participants of phospholipid metabolism: ANXA3, PLA2G2A, and phospholipid transfer protein. Tissue inhibitor of metalloproteinase 1 and secretory leucocyte protease inhibitor are inhibitors of proteases degrading extracellular matrix proteins and participating in cell proliferation regulation. MIA, SPP1, fibromodulin are modulators or participants of the interaction between extracellular matrix proteins and their cell surface receptors. SOX9 is a transcription factor required for chondrocyte differentiation. Calretenin (CALB2) is an intracellular calcium-binding protein with poorly understood function.

HMG CoA reductase and LDL receptor genes are regulated differently by 15-ketosterols in Hep G2 cells

The ability of two 15-ketosubstituted sterols, 5alpha-cholest-8(14)-en-3beta-ol-15-one and 3beta-(2-hydroxyethoxy)-5alpha-cholest-8(14)-en-15-one, to alter the mRNA levels of 3-hydroxy-3-methylglutaryl-CoA reductase, low density lipoprotein receptor, and oxysterol binding protein was studied and compared with the effects of 25-hydroxycholesterol in Hep G2 cells. All three oxysterols decreased the level of HMG CoA reductase mRNA at concentrations of 10-30 microM, although 25-hydroxycholesterol was effective at concentrations of 1-3 microM. 25-Hydroxycholesterol lowered the level of LDL receptor mRNA more efficiently after 8 hours than after 24 hours of incubation, whereas 15-ketosterols did not decrease the mRNA level of the LDL receptor. The transcriptions of HMG CoA reductase and LDL receptor genes are therefore independently regulated by 15-ketosterols in Hep G2 cells. In addition, the level of the oxysterol binding protein mRNA is not affected by oxysterols in Hep G2 cells.

Distribution of exogenous 25-hydroxycholesterol in Hep G2 cells between two different pools

Binding of [26,27-(3)H]25-hydroxycholesterol (25HC) to human hepatoma Hep G2 cells was saturated within 120 min. Two intracellular pools of 25HC were identified in a pulse-chase experiment: (i) an exchangeable pool which was in dynamic equilibrium with 25HC in the medium (t(1/2) of reversible exchange 15 min) and (ii) an unexchangeable pool which remained in cells during incubation in medium containing LPDS. 25HC from the exchangeable pool inhibits cholesterol biosynthesis, decreases the HMG CoA reductase mRNA level and stimulates cholesterol acylation. 25HC from the unexchangeable pool was partially bound to cytosolic proteins and apparently utilized for metabolic transformation. Incubation of Hep G2 cells with [26,27-(3)H]25HC in the presence of a 30-fold molar excess of 3beta-hydroxy-5alpha-cholest-8(14)-en-15-one was found to cause (i) 2-fold decrease in the binding of [26,27-(3)H]25HC to cytosolic proteins (sedimentation constant of radioactive complex was 4-5 S) and (ii) the 35% inhibition of 25HC transformation to polar metabolites.

[Analysis of gene expression pattern in peripheral blood leukocytes during experimental heat wave]

The conditions of Moscow 2010 summer heat wave were simulated in an accommodation module. Six healthy men aged from 22 to 46 years stayed in the module for 30 days. Measurements of gene expression in peripheral blood leukocytes before, during and 3 day after simulated heat wave were performed using qRT-PCR. We observed a shift in the expression level of certain genes after heat exposure for a long time, and rapid return to the initial level, when volunteers leaved the accommodation module. Eight genes were chosen to form the "heat expression signature". EGR2, EGR3 were upregulated in all six volunteers, EGR1, SIRT1, CYP51A1, MAPK9, BAG5, MNDA were upregulated in 5 volunteers.

Effect of 3-substituted Delta8(14)-15-ketosterols on cholesterol metabolism in hepatoma Hep G2 cells

The effects of 3-substituted Delta8(14)-15-ketosterols--3beta-(2-hydroxyethoxy)-, 3beta-(2-propenyloxy)-, 3beta-[2(R,S),2,3-oxidopropyloxy]-, 3beta-[2(R,S),2,3-dihydroxypropyloxy]-, 3beta-(2-oxoethoxy)-, 3beta-[2(R,S),2-acetoxy-3-acetamidopropyloxy]-, and 3beta-[2(R,S), 2-hydroxy-3-acetamidopropyloxy]-5alpha-cholest-8(14)-en-15-o nes--on cholesterol metabolism were studied in human hepatoma Hep G2 cells. 3beta-(2-Propenyloxy)-, 3beta-(2-oxoethoxy)-, and 3beta-[2(R,S),2, 3-oxidopropyloxy]-5alpha-cholest-8(14)-en-15-ones inhibited cholesterol biosynthesis without any effect on triglyceride biosynthesis, while 3beta-[2(R,S),2-acetoxy-3-acetamidopropyloxy]- and 3beta-[2(R,S), 2-hydroxy-3-acetamidopropyloxy]-5alpha-cholest-8(14)-en-15-o nes inhibited both cholesterol biosynthesis and triglyceride biosynthesis at concentrations exceeding 10 microM. 3beta-[2(R,S),2, 3-Dihydroxypropyloxy]-5alpha-cholest-8(14)-en-15-one, effectively inhibiting cholesterol biosynthesis, was found also to be toxic in Hep G2 cells at micromolar concentrations. 3beta-[2(R,S),2, 3-Oxidopropyloxy]-5alpha-cholest-8(14)-en-15-one effectively inhibited cholesterol acylation. All the tested compounds decreased the HMG-CoA reductase mRNA level at concentrations exceeding 10 microM; however, they did not affect the LDL receptor mRNA level. Among the compounds tested, only 3beta-hydroxy-5alpha-cholest-8(14)-en-15-one decreased the uptake and internalization of LDL-associated cholesteryl esters, being as effective as 25-hydroxycholesterol.

The study of nonspecific internalization of cholesteryl esters by the Hep G2 hepatoma cells

The cholesteryl oleate-POPC dispersions (1:3, mol/mol, mean particle size 110+/-20 nm) were taken up by the human hepatoma line Hep G2 cells via endocytosis. Internalization of the cholesteryl oleate-POPC dispersions by Hep G2 cells was dependent on the incubation time and dispersion concentration. At the cholesteryl oleate concentration 100 microM, its total uptake and internalization were found to be 1.5 nmol and 0.8 nmol per 1 mg of cell protein/24 h, respectively. Intracellular cleavage of the cholesteryl oleate incorporated in dispersions resulted in accumulation of free cholesterol capable of being released into the medium and metabolized to water-soluble polar products, presumably bile acids; oleic acid released is, apparently, involved in biosynthesis of triacylglycerides. The low-density lipoprotein receptor is not involved in internalization of lipid dispersions, and the presence of the cholesteryl oleate-POPC dispersions has no effect on the receptor-dependent internalization of cholesteryl esters of the low-density lipoproteins. The obtained data allow us to consider nonspecific internalization of cholesteryl esters by hepatocytes as a substantial part of the nonpolar lipid clearance.