siRNA-induced silencing of hypoxia-inducible factor 3α (HIF3α) increases endurance capacity in rats.

Molecular mechanisms of adaptation to exercise despite a large number of studies remain unclear. One of the crucial factors in this process is hypoxia inducible factor (HIF) that regulates transcription of many target genes encoding proteins that are implicated in molecular adaptation to hypoxia. Experiments were conducted on 24 adult male Fisher rats. Real-time PCR analysis was performed for quantitative evaluation of Hif3α, Igf1, Glut-4 and Pdk-1 in m. gastrocnemius, m. soleus, in lung and heart tissues. Mitochondrial respiratory function and electron microscopy were performed. Knockdown of Hif3α using siRNA increases time of swimming to exhaustion by 1.5 times. Level of mitochondrial NAD- and FAD-dependent oxidative pathways is decreased, however efficiency of phosphorylation is increased after Hif3α siRNA treatment. Expression of HIF target genes in muscles was not changed significantly, except for increasing of Pdk-1 expression in m. soleus by 2.1 times. More prominent changes were estimated in lung and heart: Igf1 gene expression was increased by 32.5 and 37.5 times correspondingly. Glut4 gene expression in lungs was increased from undetected level till 0.3 rel. units and by 84.2 times in heart. Level of Pdk1 gene expression was increased by 249.2 in lungs and by 35.1 times in hearts, correspondingly. Some destructive changes in muscle tissue were detected in animals with siRNA-inducing silencing of Hif3α.

Silencing of TERT decreases levels of miR-1, miR-21, miR-29a and miR-208a in cardiomyocytes.

To test the hypothesis that telomerase reverse transcriptase (TERT) as an RNA-dependent RNA polymerase could be involved in the amplification of microRNA (miRNA), we have determined the levels of immature and mature miRNA in cultured neonatal rat cardiomyocytes, during the silencing of TERT by siRNA. The silencing of the TERT gene led to the reduction of both telomerase activity and the TERT mRNA expression when compared with scrambled RNA. TERT gene silencing resulted in the decrement of three studied mature miRNAs levels: miRNA-21, miRNA-29a and miRNA-208a when compared with scrambled RNA; but miRNA-1, it was not changed significantly. At the same time, levels of immature miRNA-1 and miRNA-208a were not changed, although the levels of immature miRNA-29a and pri-miRNA-1 were decreased. The data obtained allow us to permit that TERT is a genome-independent source of mature miRNA, and the changes in telomerase activity can significantly influence the level of miRNA in cardiomyocytes.

The involvement of peroxisome proliferator-activated receptor gamma (PPARγ) in anti-inflammatory activity of N-stearoylethanolamine.

Background: N-stearoylethanolamine (NSE) is a bioactive lipid amine with a wide range of biological activities. Anti-inflammatory properties of NSE were previously confirmed on multiple animal models. However, the molecular mechanisms of anti-inflammatory action of NSE remain unclear. In the current study, we examined the involvement of nuclear receptor peroxisome proliferator-activated receptor gamma (PPARγ) in the NF-kB -dependent pathway of anti-inflammatory action of NSE using different methodological approaches. Methods: Molecular modeling calculated the possibility of NSE binding PPAR. Ex vivo experiment, using selective agonist of PPARα/γ - LY-171883 and antagonist of PPARγ - GW9662, examined the role of PPARα/γ in the NSE's effect on nuclear NF-kB translocation in LPS-activated rat peritoneal macrophages. Finally, the NSE's action on mRNA level of PPARγ-dependent genes was studied in the liver of insulin-resistant rats. Results: The results of molecular docking showed that NSE could bind to PPARγ and compete for the binding site with antagonist GW9662 and agonist LY-171883. These data was supported by in vitro study where pre-treatment with NSE prevented further LPS-induced NF-kB translocation into the nuclei of rat peritoneal macrophages. NSE treatment before GW9662 and LPS addition normalized the level of NF-kB translocation and IL-1ß content. This finding confirmed a competitive binding of NSE with GW9662 for the ligand-binding domain of PPARγ. Additional in vivo study showed that NSE administration changed the mRNA expression of several PPARγ target genes, including SLC27A1 encoding fatty acid transport protein-1 and IL1RN - interleukin-1 receptor antagonist in insulin resistant rats. Conclusion: NSE suppressed nuclear translocation of NF-κB in LPS-stimulated peritoneal macrophages via PPARγ and changed hepatic mRNA expression of PPARγ target genes (SLC27A1, IL1RN) in insulin resistant rats.

The protective effect of Hif3a RNA interference and HIF-prolyl hydroxylase inhibition on cardiomyocytes under anoxia-reoxygenation.

The aim of this study was to investigate the molecular mechanisms underlying the protective effects of hypoxia-inducible factor (HIF) signaling pathway activation in cardiomyocytes under anoxia-reoxygenation (A/R) injury. In this study, rat neonatal cardiomyocytes were pretreated with anti-Hif3A/Hif-3α siRNA or HIF-prolyl hydroxylase inhibitor prior to A/R injury. Our results showed that both HIF3A silencing and HIF-prolyl hydroxylase inhibition effectively increased the cell viability during A/R, led to changes in mRNA expression of HIF1-target genes, and reduced the loss of mitochondrial membrane potential (Δψm). Furthermore, application of anti-Hif3a siRNA led to an increase in mRNA expression of Epo, Igf1, Slc2a1/Glut-1, and Slc2a4/Glut-4. Similar results were observed with HIF-prolyl hydroxylase inhibition, which additionally upregulated the mRNA expression of Epor, Tert, and Pdk1. Hif3a RNA-interference and application of HIF-prolyl hydroxylase inhibitor during A/R modelling led to an increase of Δψm on 11.5 and 11.9 mV respectively, compared to the control groups. Thus, Hif3a RNA interference and HIF-prolyl hydroxylase inhibition protect cardiomyocytes against A/R injury via the HIF signaling pathway.

[EFFECT OF CURCUMIN ON MITOCHONDRIAL FUNCTION OF CARDIOMYOCYTES WITH DOXORUBICIN-INDUCED OXIDATIVE STRESS].

We studied the effect of curcumin on the cardiomyocytes viability, processes of oxidative phosphorylation in the mitochondria of cardiomyocytes, their pro- and antioxidant balance in doxorubicin-induced oxidative stress. It has been revealed that administration of doxorubicin to rats led to a significant increase in the secondary products of lipid peroxidation (TBARS) in mitochondria by 21 and H(2)0(2) by 76%, reduction of the enzymatic activity of mitochondrial Mn-SOD by 14% and intensified catalase activity by 80% compared with the control. After combined use of doxorubicin and curcumin the content of TBARS and H(2)0(2) increased by 14 and 26%, respectively, the enzymatic activity of catalase decreased by 28%, and mitochondrial Mn-SOD activity intensified by 9%. During the incubation with doxorubicin, the number of live cells decreased by 30.4% and the number of necrotic cells increased by 30.4% relative to control. Coadministration of doxorubicin and curcumin led to augmented cell viability by 8%, while the number of necrotic cells reduced by 8% compared with the use of doxorubicin only. In assessing the parameters of mitochondrial respiration in rats that received injections of doxorubicin active breathing index (V(3)) fell by 43.8%, the oxidation rate of the contingency of phosphorylation (V(3)/V(4)(ATp)) decreased by 47% and phosphorylation efficiency index (ADP/O) also declined by 31.7% respectively compared with the control. The combined use of doxorubicin and curcumin improved the indicators of mitochondrial respiration compared to using only doxorubicin: V(3) raised by 25%, V(3)/V(4)(ATP)by 18% and ADP/O by 12% respectively.

DOXORUBICIN-INDUSED DISTURBANCES OF CARDIOMYOCYTE CONTRACTILE ACTIVITY.

The aim of our study was to find out the mechanisms of cardiomyocyte contractile activity disturbances under the influence of anthracycline antibiotics and curcumin correction capabilities, to clarify the role of the mitochondrial membrane potential changes in cardiomyocyte contractile activity. It was investigated disturbances of contractile activity of the rat neonatal cardiomyocytes under the influence of anthracycline antibiotics (doxorubicin), and the possibility of correcting these violations using antioxidant curcumin. In addition, there was researched the role of mitochondrial membrane potential changes in reducing contractile activity of the cardiomyocytes. We established that doxorubicin causes significant changes in all reduction parameters compared to control: increased frequency of spontaneous contractions, violation of rhythm, lower amplitude and the shortening %, increase in the maximum speed of contraction and relaxation without changes in duration of these processes. Compatible incubation with doxorubicin and curcumin caused a consid- erable decrease of the incidence of spontaneous emission (3 times), restored their rhythm, increasing the amplitude of 2 times and the shortening % (8,15 ± 0,37), rising the maximum speed reduction to 1,8 times and the relaxation speed of 16 %, with no significant change in duration of these processes compared to monoincubation with doxorubicin. In the fluorescence study of neonatal cardiomyocytes mitochondrial potential was detected a significant reduction in mitochondria color brightness under the influence of doxorubicin - in 1,7 times compared to control. A compatible incubation of cells with curcumin and doxorubicin resulted in an elevation of mitochondria fluorescence (2,2 times compared to using of doxorubicin only).

[DOXORUBICIN-INDUCED ALTERATIONS IN PRO-AND ANTIOXIDANT BALANCE AND THEIR CORRECTION BY CURCUMIN IN THE NEONATAL RAT CARDIOMYOCYTES CULTURE].

It was studied the effect of doxorubicin on the HIF system and the pro-antioxidant balance of neonatal cardiomyocytes as well as the possibility of the oxidative stress correcting using curcumin. It has been revealed that the expression of mRNA HIF-1α using doxorubicin at a dose of 0.5 µM was 2.9 ± 0.8 cu, so it decreased by 20% compared to control--3.6 ± 0.7 cu (P < 0.05). The level of expression of the HIF target gene PDK-1 also significantly decreased (4 times). During the incubation with doxorubicin, the number of live cells decreased by 50.4% relative to control. And after using doxorubicin and curcumin together, the percentage of dead cells decreased by 7,7 compared to doxorubicin only. Doxorubicin intoxication led to a significant increase in the secondary products of lipid peroxidation (TBARS) in cardiomyocytes by 3.6 times and hydrogen peroxide by 64%. Prolonged incubation with doxorubicin reduced the enzymatic activity of Mn-SOD by 32%, while catalase activity increased by 72% compared to control. Adding of curcumin to the cardiomyocyte cell culture contributed to increasing of the Mn-SOD activity by 14%, catalase--by 23%. The level of TBARS increased by 1,4 times compared with the control, and the level of H2O2 increased by 20%. The joint use of doxorubicin and curcumin resulted in a significant reduction of free radical oxidation unlike effect of doxorubicin per se. Specifically, there was lessening of TBARS and H2O2 (at 56.7 and 18.4% respectively), while decreasing of the catalase hyperactivation (19%) and rising of the Mn-SOD activity (35%).

Genetic predisposition to essential hypertension in children: analysis of 17 single nucleotide polymorphisms.

Study of 17 single nucleotide polymorphisms has been performed to determine the factors of genetic predisposition to essential hypertension. Polymerase chain reaction (PCR) with subsequent analysis of restriction fragment length, allele specific PCR or real-time PCR was used for genotyping of 17 single nucleotide polymorphisms in 14 genes in 145 children with essential hypertension and 144 healthy persons with following complex multivariate statistical analysis. Two single nucleotide polymorphisms--MMP9 (C(-1562) --> T) and NOS3 (Glu298 --> Asp)--rs3918242 and rs1799983--were shown to represent the main independent effects with the highest predictive potential (77.1% as indicated by binary logistic regression and 74.6% testing accuracy shown by Multifactorial Dimensionality Reduction). MMP9 (C(-1562 --> T) and NOS3 (Glu298 --> Asp) potentially may be used to create predictive algorithm for determination of predisposition to arterial hypertension in children.

HIF-3α mRNA expression changes in different tissues and their role in adaptation to intermittent hypoxia and physical exercise.

The role of HIF-3α in response to intermittent hypoxia and physical exercise was investigated in Fisher rats using reverse transcription, real-time PCR and RNA interference. Under acute hypoxia (12% O(2), 2h), the level of HIF-1α, HIF-2α, and HIF-1ß mRNA did not significantly change in the heart, lung, kidney and muscle tissues, but HIF-3α mRNA expression was strongly elevated in all tissues investigated. Five weeks of intermittent hypoxic training (IHT) led to an increase of HIF-3α mRNA in all studied tissues, but under the influence of acute hypoxia after IHT, the expression of HIF-3α mRNA did not increase in all tissues excluding skeletal muscle. Thus, IHT reduced the effect of acute hypoxia on HIF-3α mRNA expression in the heart, lung, and kidney. The expression of HIF-3α in skeletal muscle at endurance (swimming) training (ET) in combination with IHT was 6.2 times lower compared to the group with ET but without IHT and 3.3 times lower (P<0.05) compared to untrained control. After swimming training with IHT, rats demonstrated the highest level of physical endurance. RNA interference of HIF-3α significantly decreased the level of HIF-3α mRNA in both muscles investigated: by 2.6 times in m. soleus (P<0.03) and by 2.1 times in m. gastrocnemius (P<0.05) and elevated the physical endurance of rats by 50% (P<0.05) compared to control. Thus, the HIF-3α subunit is an essential member of hypoxic response. It plays a negative role in the adaptation to hypoxia, because the inhibition of HIF-3α expression leads to an increase in physical endurance.