Metabolic Regulatory Mechanisms Research Articles

Imatinib reduces cholesterol uptake and matrix metalloproteinase activity in human THP-1 macrophages.

Imatinib mesylate (Glivec®, formerly STI-571) is a selective tyrosine kinase inhibitor used for the treatment of chronic myeloid leukemia and gastrointestinal stromal tumors. However, there are reports suggesting that imatinib could be atheroprotective by lowering plasma low-density lipoprotein (LDL). To investigate the potential inhibitory effect of imatinib on cholesterol uptake in human macrophages as well as its effect on matrix metalloproteinase (MMP) activity. Uptake of fluorescence-labeled LDL was analyzed using flow cytometry. Macrophages treated with imatinib showed a 23.5%, 27%, and 15% decrease in uptake of native LDL (p<0.05), acetylated LDL (p<0.01), and copper-modified oxidized LDL (p<0.01), respectively. Gel-based zymography showed that secretion and activity of MMP-2 and MMP-9 were inhibited by imatinib. Using GeneChip Whole Transcript Expression array analysis, no obvious gene candidates involved in the mechanisms of cholesterol metabolism or MMP regulation were found to be affected by imatinib. Instead, we found that imatinib up-regulated microRNA 155 (miR155) by 43.8% and down-regulated ADAM metallopeptidase domain 28 (ADAM28) by 41.4%. Both genes could potentially play an atheroprotective role and would be interesting targets in future studies. Our results indicate that imatinib causes post-translational inhibition with respect to cholesterol uptake and regulation of MMP-2 and MMP-9. More research is needed to further evaluate the role of imatinib in the regulation of other genes and processes.

Splenic monocytes traffic to the thyroid and produce a novel TSHβ splice variant during acute Listeria infection in mice (INC4P.334)

Abstract It has been known for over three decades that thyroid stimulating hormone (TSH) is produced by cells of the immune system; however, the functional role of that TSH has remained obscure. We recently identified a novel splice variant of the thyroid stimulating hormone β-subunit (TSHβv) that is primarily produced by cells of the immune system, in particular by myeloid cells in the bone marrow (BM) and spleen. During acute infection with virulent L. monocytogenes, TSHβv synthesis increased in CD14+, F4/80+ BM cells and spleen cells. In vitro culture of the mouse AM macrophage cell line with LPS or zymosan, or following stimulation with anti-CD14 or anti-TLR2 antibodies, resulted in increased synthesis of TSHβv. Three days post-infection with Listeria, there was an infiltration of CD14+, F4/80+ cells into the thyroid that was followed by an increase in intrathyroidal TSHβv gene expression on days 4 and 5 compared to non-infected mice. Following in vivo transfer of CFSE-labeled spleen cells from infected mice into normal non-infected mice, CFSE+ cells were present throughout the thyroid, demonstrating an active process of trafficking of TSHβv-producing spleen cell into the thyroid during an acute infection. These findings point to a novel mechanism of host metabolic regulation by the immune system during systemic bacterial infection, and they define a functional role for TSHβv in that process.

Investigation into the role of catabolite control protein A in the metabolic regulation of Streptococcus suis serotype 2 using gene expression profile analysis.

Catabolite control protein A (CcpA) serves a key function in the catabolism of Streptococcus suis serotype 2 (S. suis 2) by affecting the biological function and metabolic regulatory mechanisms of this bacterium. The aim of the present study was to identify variations in CcpA expression in S. suis 2 using gene expression profile analysis. Using sequencing and functional analysis, CcpA was demonstrated to play a regulatory role in the expression and regulation of virulence genes, carbon metabolism and immunoregulation in S. suis 2. Gene Ontology and Kyto Encyclopedia of Genes and Genomes analyses indicated that CcpA in S. suis 2 is involved in the regulation of multiple metabolic processes. Furthermore, combined analysis of the transcriptome and metabolite data suggested that metabolites varied due to the modulation of gene expression levels under the influence of CcpA regulation. In addition, metabolic network analysis indicated that CcpA impacted carbon metabolism to a certain extent. Therefore, the present study has provided a more comprehensive analysis of the role of CcpA in the metabolic regulation of S. suis 2, which may facilitate future investigation into this mechanism. Furthermore, the results of the present study provide a foundation for further research into the regulatory function of CcpA and associated metabolic pathways in S. suis 2.

Activation of the Liver X Receptor by Agonist TO901317 Improves Hepatic Insulin Resistance via Suppressing Reactive Oxygen Species and JNK Pathway.

Activation of Liver X receptors (LXRs), key transcriptional regulators of glucose metabolism, normalizes glycemia and improves insulin sensitivity in rodent models with insulin resistance. However, the molecular mechanism is unclear. This study is aimed to elucidate the mechanism of LXRs-mediated liver glucose metabolic regulation in vitro and in vivo. Db/db mice were used as an in vivo model of diabetes; palmitate (PA)-stimulated HepG2 cells were used as an in vitro cell model with impairment of insulin signaling. TO901317 (TO) was chosen as the LXRs agonist. We demonstrated that TO treatment for 14 days potently improved the hepatic glucose metabolism in db/db mice, including fasting blood glucose, fasting insulin level, and HOMA-IR. TO had no effect on the glucose metabolism in normal WT mice. TO-mediated activation of hepatic LXRs led to strong inhibition of ROS production accompanied by inactivation of JNK pathway and re-activation of Akt pathway. TO also suppressed the expression of gluconeogenic genes such as PEPCK and G-6-pase in db/db mice, but not in WT mice. In HepG2 cells, TO almost completely restored PA-induced Akt inactivation, and suppressed PA-stimulated ROS production and JNK activation. Interestingly, basal level of ROS was also inhibited by TO in HepG2 cells. TO significantly inhibited PA-stimulated expressions of gluconeogenic genes. Finally, we found that anti-oxidative genes, such as Nrf2, were up-regulated after LXRs activation by TO. These results strongly support the notion that activation of LXRs is critical in suppression of liver gluconeogenesis and improvement of insulin sensitivity in diabetic individuals. At molecular levels, the mode of action appears to be as fellows: under diabetic condition, ROS production is increased, JNK is activated, and Akt activity is inhibited; TO-mediated LXR activation potently inhibits ROS production, increases anti-oxidative gene expressions, suppresses JNK activation, and restores Akt activity. Our data provide new evidence to support LXRs as promising therapeutic targets for anti-diabetic drug development.

Recent functional insights into the role of (p)ppGpp in bacterial physiology.

The alarmones guanosine tetraphosphate and guanosine pentaphosphate (collectively referred to as (p)ppGpp) are involved in regulating growth and several different stress responses in bacteria. In recent years, substantial progress has been made in our understanding of the molecular mechanisms of (p)ppGpp metabolism and (p)ppGpp-mediated regulation. In this Review, we summarize these recent insights, with a focus on the molecular mechanisms governing the activity of the RelA/SpoT homologue (RSH) proteins, which are key players that regulate the cellular levels of (p)ppGpp. We also discuss the structural basis of transcriptional regulation by (p)ppGpp and the role of (p)ppGpp in GTP metabolism and in the emergence of bacterial persisters.

Interphase microbial community characteristics in the fermentation cellar of Chinese Luzhou-flavor liquor determined by PLFA and DGGE profiles

In view of the equilibrium of fermentation rate in the cellar mainly depends on interphase microflora, it is essential to exploit interphase microbial community characteristics to understand the metabolic regulation mechanism. The objective of this study was to investigate interphase microbial community structure in the fermentation cellar of Chinese Luzhou-flavor liquor via combining phospholipid fatty acids (PLFAs) and denaturing gradient gel electrophoresis (DGGE). The total microbial biomass analyzed by PLFA in the pit mud (PM: 25.52–103.38nmol/g) and Zaopei (ZP: 29.96–64.50nmol/g) was obviously higher than Huangshui (HS: 4.35–7.82nmol/g), and was strongly correlated with pit age, which was validated by DGGE results. Among the specific microbial groups, ‘gram-positive bacteria, anaerobe bacteria and fungi’ dominated in the PM, while ‘gram-positive bacteria, aerobe bacteria and fungi’ predominated in the ZP and HS, respectively. Principal component analysis (PCA) based ordination of the relative PLFA abundance data segregated PM, ZP and HS. Eubacterial PCR-DGGE illustrated that a total of 31 bands belonged to five families (Lactobacillaceae, Clostridiaceae, Porphyromonadaceae, Synergistaceae and Acetobacteraceae) were identified, and 41.52% eubacteria were affiliated with Lactobacillaceae in the ZP, while 44.67% and 40.41% eubacteria were affiliated with Clostridiaceae in the PM and HS, respectively. Archaeal PCR-DGGE analysis demonstrated that Methanosaeta, Methanocorpusculum, Methanobrevibacter, Methanobacterium and Methanoculleus were the majority of archaea. Particularly, Methanosaeta, as acetrophic methanogens, increased gradually in the PM and HS with pit age, and decreased in the ZP, and no family Methanobacteriaceae was detected in the 30-year-PM. Furthermore, fungal community was dominated by genus Pichia.

Current status and future perspectives of kinetic modeling for the cell metabolism with incorporation of the metabolic regulation mechanism

It becomes more and more important to develop appropriate models for the efficient design of the cell factory for microbial biofuels and biochemical productions, since the appropriate model can predict the effect of culture environment and/or the specific pathway genes knockout on the growth characteristics. Among various modeling approaches, kinetic modeling is promising in the sense of realizing the essential feature of metabolic regulation. A brief overview is given for the current status of the kinetic modeling of the cell metabolism from the point of view of metabolic regulation focusing on Escherichia coli (but not limited to E. coli). For the proper modeling, it is important to realize the systems behavior by integrating different levels of information to understand and unravel the underlying principles of the living organisms, namely, it is important to properly understand how the environmental stimuli are detected by the cell, how those are transduced, and how the cell metabolism is regulated, and to express these into the model. In particular, it is important to incorporate the enzymatic regulations of Pyk, Pfk, and Ppc by fructose-1,6-bisphosphate (FBP), phosphoenol pyruvate (PEP), and acetyl-coenzyme A (AcCoA) to realize the flux-sensing and homeostatic behavior. The proper modeling for phosphotransferase system (PTS) and the transcriptional regulation by cAMP-Crp and Cra is also important to simulate the main metabolism in relation to catabolite regulation. The coordinated regulation between catabolic and anabolic (nitrogen source-assimilation) metabolisms may be simulated by the behavior of keto acid such as α-ketoglutarate (αKG). The metabolism under micro-aerobic conditions may be made by incorporating the global regulators such as ArcA/B and Fnr. It is quite important to develop quantitative kinetic models, which incorporate enzyme level and gene level regulations from the biological science and metabolic engineering points of view.

Solanesol: a review of its resources, derivatives, bioactivities, medicinal applications, and biosynthesis

Solanesol, which mainly accumulates in solanaceous crops, including tobacco, tomato, potato, eggplant, and pepper plants, is a long-chain polyisoprenoid alcohol compound with nine isoprene units. Chemical synthesis of solanesol is difficult; therefore, solanesol is primarily extracted from solanaceous crops, particularly tobacco leaves. In plants, solanesol exists in both free and esterified forms, and its accumulation is influenced by genetic and environmental factors. Solanesol is widely used in the pharmaceutical industry as an intermediate for the synthesis of ubiquinone drugs, such as coenzyme Q10 and vitamin K2. Solanesol possesses antibacterial, antifungal, antiviral, anticancer, anti-inflammatory, and anti-ulcer activities, and solanesol derivatives also have anti-oxidant and antitumour activities, in addition to other bioactivities. Solanesol derivatives can also be used for the treatment of cardiovascular disease, osteoporosis, acquired immune deficiency syndrome, and wound healing. Solanesol biosynthesis occurs in plastids of higher plants via the 2-C-methyl-d-erythritol-4-phosphate (MEP) pathway. The key enzymes in solanesol biosynthesis, including 1-deoxy-d-xylulose-5-phosphate synthase, 1-deoxy-d-xylulose-5-phosphate-reductoisomerase, isopentenyl pyrophosphate isomerase, and solanesyl diphosphate synthase, are also important regulators of the MEP pathway, and their overexpression is favourable for downstream metabolic flow, further promoting the synthesis of downstream metabolites, such as solanesol. Future studies should determine the pharmacokinetic properties of solanesol and its derivatives and investigate the metabolic pathways and regulatory mechanisms mediating solanesol biosynthesis, metabolic and genetic engineering of solanesol, the synthetic biology of solanesol, and the physiological role of solanesol. In the present review, we systematically summarise current knowledge on solanesol resources, derivatives, bioactivities and medicinal applications, metabolic pathways, and key biosynthetic enzymes.

Differential metabolic responses of Beauveria bassiana cultured in pupae extracts, root exudates and its interactions with insect and plant

Beauveria bassiana is a kind of world-wide entomopathogenic fungus and can also colonize plant rhizosphere. Previous researches showed differential expression of genes when entomopathogenic fungi are cultured in insect or plant materials. However, so far there is no report on metabolic alterations of B. bassiana in the environments of insect or plant. The purpose of this paper is to address this problem. Herein, we first provide the metabolomic analysis of B. bassiana cultured in insect pupae extracts (derived from Euproctis pseudoconspersa and Bombyx mori, EPP and BMP), plant root exudates (derived from asparagus and carrot, ARE and CRE), distilled water and minimal media (MM), respectively. Principal components analysis (PCA) shows that mycelia cultured in pupae extracts and root exudates are evidently separated and individually separated from MM, which indicates that fungus accommodates to insect and plant environments by different metabolic regulation mechanisms. Subsequently, orthogonal projection on latent structure–discriminant analysis (OPLS-DA) identifies differential metabolites in fungus under three environments relative to MM. Hierarchical clustering analysis (HCA) is performed to cluster compounds based on biochemical relationships, showing that sphingolipids are increased in BMP but are decreased in EPP. This observation further implies that sphingolipid metabolism may be involved in the adaptation of fungus to different hosts. In the meantime, sphingolipids are significantly decreased in root exudates but they are not decreased in distilled water, suggesting that some components of the root exudates can suppress sphingolipid to down-regulate sphingolipid metabolism. Pathway analysis finds that fatty acid metabolism is maintained at high level but non-ribosomal peptides (NRP) synthesis is unaffected in mycelia cultured in pupae extracts. In contrast, fatty acid metabolism is not changed but NRP synthesis is high in mycelia cultured in root exudates and distilled water. This indicates that fungal fatty acid metabolism is enhanced when contacting insect, but when in the absence of insect hosts NRP synthesis is increased. Ornithine, arginine and GABA are decreased in mycelia cultured in pupae extracts and root exudates but remain unchanged in distilled water, which suggests that they may be associated with fungal cross-talk with insects and plants. Trehalose and mannitol are decreased while adenine is increased in three conditions, signifying carbon shortage in cells. Together, these results unveil that B. bassiana has differential metabolic responses in pupae extracts and root exudates, and metabolic similarity in root exudates and distilled water is possibly due to the lack of insect components.

Facts, Challenges, Difficulties and Hopes in Single-Cell Biology: Physiopathological Studies

Single-cell approaches are being increasingly used to unravel the many diverse mechanisms underlying biological processes that characterize each cell irrespective of the influx of other cells even within the same tissue. Consequently, the interference of metabolites and nervous stimuli emanating from the circulatory or nervous system in a higher organism like man is avoided. However, while the single-cell approach yields a wealth of data about single-cell metabolism and internal regulatory mechanisms, information about interactions and interrelations among similar or dissimilar cells may remain obscure. Starting from these considerations, here we summarize, without attempting to be exhaustive, some areas in which we think single-cell biological studies could be effective in translational medicine and in other areas of applied sciences. In this short review we describe the facts, challenges and perspectives related to these issues.

Plasma metabonomic analysis reveals the effects of salvianic acid on alleviating acute alcoholic liver damage

This study analysed acute alcohol-induced metabolic changes and explored the metabolic regulation mechanism of SA treatment by using 1H NMR-based metabonomics.

Metabolic Regulation and Coordination of the Metabolism in Bacteria in Response to a Variety of Growth Conditions.

Living organisms have sophisticated but well-organized regulation system. It is important to understand the metabolic regulation mechanisms in relation to growth environment for the efficient design of cell factories for biofuels and biochemicals production. Here, an overview is given for carbon catabolite regulation, nitrogen regulation, ion, sulfur, and phosphate regulations, stringent response under nutrient starvation as well as oxidative stress regulation, redox state regulation, acid-shock, heat- and cold-shock regulations, solvent stress regulation, osmoregulation, and biofilm formation, and quorum sensing focusing on Escherichia coli metabolism and others. The coordinated regulation mechanisms are of particular interest in getting insight into the principle which governs the cell metabolism. The metabolism is controlled by both enzyme-level regulation and transcriptional regulation via transcription factors such as cAMP-Crp, Cra, Csr, Fis, P(II)(GlnB), NtrBC, CysB, PhoR/B, SoxR/S, Fur, MarR, ArcA/B, Fnr, NarX/L, RpoS, and (p)ppGpp for stringent response, where the timescales for enzyme-level and gene-level regulations are different. Moreover, multiple regulations are coordinated by the intracellular metabolites, where fructose 1,6-bisphosphate (FBP), phosphoenolpyruvate (PEP), and acetyl-CoA (AcCoA) play important roles for enzyme-level regulation as well as transcriptional control, while α-ketoacids such as α-ketoglutaric acid (αKG), pyruvate (PYR), and oxaloacetate (OAA) play important roles for the coordinated regulation between carbon source uptake rate and other nutrient uptake rate such as nitrogen or sulfur uptake rate by modulation of cAMP via Cya.

MECHANISMS OF ACTION OF THE POWDER OF CURCUMA LONGA RHIZOME PLANT ON A CARBOHYDRATE METABOLISM AT ALLOXAN-INDUCED DIABETIC RATS

Aim. The effects of the powder of Curcuma longa plant rhizome as food additive on different processes of carbohydrate metabolism: glucose concentration in whole blood, concentration of hormones – insulin and C-peptide in plasma, content of glycogen in the liver, structural and functional organization of the islet apparatus of the pancreas in rats with alloxan-induced diabetes mellitus were studied. Material and methods. The study was conducted on Wistar adult male rats. All animals were divided into 4 groups: 1 and 2 – the controls, 3 and 4 – the rats with alloxan-induced model of diabetes mellitus. Animals of groups 1 and 3 were kept on standard chow, whereas the rats of groups 2 and 4 were feeded with additive of powder from Curcuma longa plant rhizome (2% by weight of feed). The concentration of glucose in blood and perfused solution was determined with picric acid method by intensity of colour reaction on spectrofotometer. Concentration of hormones (insulin, C-peptide) was defined by immunoenzyme method with standard sets on tablet spectrofotometer. The morphological structure of a pancreas was studied by a method of light microscopy. Content of glycogen in a liver was measured by means of Shick-reaction on the Mac-Manus method with measurement of colour intensity on spectrofotometer. Results. Intake of the turmeric rhizomes powder by rats with diabetes, as compared with the diabetic animals on a standard diet, resulted in the lower increase of the glucose concentration in blood, the decrease of glucose absorption in the gut, higher concentration of the insulin and C-peptide in plasma and significant increase of glycogen content in the liver. The microstructure of pancreatic tissue samples of experimental animals using turmeric intake, was characterized by the better preservation of the islet apparatus in comparison with a group of animals on a standard diet. Conclusion. The results indicate the positive effect of the Curcuma longa rhizomes on the homeostatic mechanisms of the carbohydrate metabolism regulation in the alloxan-induced diabetes mellitus rats.

Absence of glucagon and insulin action reveals a role for the GLP-1 receptor in endogenous glucose production.

The absence of insulin results in oscillating hyperglycemia and ketoacidosis in type 1 diabetes. Remarkably, mice genetically deficient in the glucagon receptor (Gcgr) are refractory to the pathophysiological symptoms of insulin deficiency, and therefore, studies interrogating this unique model may uncover metabolic regulatory mechanisms that are independent of insulin. A significant feature of Gcgr-null mice is the high circulating concentrations of GLP-1. Hence, the objective of this report was to investigate potential noninsulinotropic roles of GLP-1 in mice where GCGR signaling is inactivated. For these studies, pancreatic β-cells were chemically destroyed by streptozotocin (STZ) in Gcgr(-/-):Glp-1r(-/-) mice and in Glp-1r(-/-) animals that were subsequently treated with a high-affinity GCGR antagonist antibody that recapitulates the physiological state of Gcgr ablation. Loss of GLP-1 action substantially worsened nonfasting glucose concentrations and glucose tolerance in mice deficient in, and undergoing pharmacological inhibition of, the GCGR. Further, lack of the Glp-1r in STZ-treated Gcgr(-/-) mice elevated rates of endogenous glucose production, likely accounting for the differences in glucose homeostasis. These results support the emerging hypothesis that non-β-cell actions of GLP-1 analogs may improve metabolic control in patients with insulinopenic diabetes.

Abstract 3607: Modulation of neuroblastoma metabolism by an extracellular chaperone SPARC

Abstract Secreted Protein Acidic and Rich in Cysteine (SPARC) is an extracellular matrix protein with diverse biologic functions. We have shown that SPARC is a scavenger chaperone that regulates matrix degradation, remodeling, and repair. We have also demonstrated that SPARC blocks angiogenesis and inhibits the growth of several cancers, including neuroblastoma. In this study we examined how extracellular chaperone SPARC affects neuroblastoma tumor progression. The chaperone properties of SPARC were characterized with cell biology methods and Surface Plasmon Resonance. Neuroblastoma cell lines derived from the high-risk tumors were treated with SPARC. The effect of SPARC on cancer cell metabolism was characterized using the Seahorse analyzer with and without inhibitors of glycolysis and mitochondrial oxidation. Standard cell culture techniques were used to assess the effect of SPARC-induced metabolic changes on neuroblastoma cell proliferation and survival. We demonstrate that SPARC functions as a chaperone, shuttling extracellular ligands between cellular and extracellular tissue compartments. We characterize physical and biological properties of SPARC-mediated ligand transport, and further demonstrate that as a chaperone, SPARC can significantly affect tissue physiology, to the degree of altering cell metabolism. We show that in addition to inhibition of neuroblastoma progression in vivo, SPARC-induced changes in cellular metabolism severely impair neuroblastoma growth and survival in vitro. This novel mechanism of metabolism regulation by an extracellular chaperone SPARC may lead to additional insights into the therapy of neuroblastoma. Citation Format: Alexandre Chlenski, Marija Dobratic, Helen R. Salwen, Mark Applebaum, Susan L. Cohn. Modulation of neuroblastoma metabolism by an extracellular chaperone SPARC. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3607. doi:10.1158/1538-7445.AM2014-3607

Regulation mechanisms in mixed and pure culture microbial fermentation.

Mixed-culture fermentation is a key central process to enable next generation biofuels and biocommodity production due to economic and process advantages over application of pure cultures. However, a key limitation to the application of mixed-culture fermentation is predicting culture product response, related to metabolic regulation mechanisms. This is also a limitation in pure culture bacterial fermentation. This review evaluates recent literature in both pure and mixed culture studies with a focus on understanding how regulation and signaling mechanisms interact with metabolic routes and activity. In particular, we focus on how microorganisms balance electron sinking while maximizing catabolic energy generation. Analysis of these mechanisms and their effect on metabolism dynamics is absent in current models of mixed-culture fermentation. This limits process prediction and control, which in turn limits industrial application of mixed-culture fermentation. A key mechanism appears to be the role of internal electron mediating cofactors, and related regulatory signaling. This may determine direction of electrons towards either hydrogen or reduced organics as end-products and may form the basis for future mechanistic models.

Investigation of the role of i1- and i2-imidazoline receptors in the mechanіsm of the hypoglycemic action of n,n’-(ethane-1,2 dyyil)bis(quinoline- 2-carboxamide)

The results of the investigation of the hypoglycemic action mechanism of N,N’-(ethane-1,2-dyyil)bis (quinoline-2-carboxamide) are presented. The substance was administered intragastrically in the dose of 11.64 mg/kg on the model of alloxan-induced diabetes mellitus in rats. It should be noted that the test compound in terms of the theory of pharmacophore can be considered as a dimer BU 224, but it is not its dimer in terms of organic chemistry. The information about the influence of the test compound on carbohydrate metabolism is limited. There are data that this compound has antitumor properties іn vitro due to enhanced apoptosis and activation of caspase-3. Proceeding from the chemical structure, the 2-substituted quinoline fragment is present in the structure of the known antagonist of imidazoline receptors I 2 such as 2-(4,5-dihydroimidazol-2-yl)quinoline hydrochloride, so it can be assumed that N,N’-(ethane-1,2-dyyil)bis(quinoline-2-carboxamide) has the ability to interfere with the mechanisms of the carbohydrate metabolism regulation. These results indicate that N,N’-(ethane-1,2-dyyil)bis(quinolin-2-carboxamide) has an expressed hypoglycemic effect in alloxan-induced diabetes mellitus reducing the blood glucose level by 71.50%. It is an agonist of imidazoline receptors of both types, and it has been proven by blockade with selective antagonists such as efaroxan and 2-(4,5-dihydroimidazol-2-yl)quinoline hydrochloride. On the background of I 1 -imidazoline receptors blocker efaroxan the glycemia decrease was 45.66% (p<0.05), and on the background of I2-imidazoline receptors blocker 2-(4,5-dihydroimidazol-2-yl)quinoline hydrochloride it was 54.01% (p<0.05). Diabetes mellitus (DM) type 2 is a chronic disease caused by decrease in sensitivity of the human tissues to insulin [1, 14]. The frequency of diabetes on average ranges from 1.5% to 3%; it is constantly increasing in the developed countries up to 5-7%, in Ukraine the value is twice lower – about 2.9%. There are about 200 million of diabetics in the world; almost 90% of them suffer from type 2 diabetes [5, 15]. The urgency of DM problem is caused by a signifi cant prevalence of the disease, severity of complications, disability and early mortality. Microangiopathies and neuropathies are the basis of diabetic complications. The patients with diabetes have a significant risk of athero sclerosis and coronary heart disease. More than 40% of amputations of lower limbs are a consequence of the diabetic foot syndrome. Diabetes is also the most common cause of blindness in humans [12, 17]. All mentioned above stipulates the necessity of development and research of new effective drugs with the hypoglycemic effect allowing to prevent development of the severe course of DM. The mechanism of action of different antidiabetic drugs consists of a several links. There are data on the role of imidazoline receptors in implementation of the hypoglycemic effect, in particular for biguanides derivatives such as metformin [7]. Imidazoline receptors are the independent type of receptors represented by two subtypes: 11 and 12. Subtypes are distinguished according to the specific ligands that bind with them. Imidazoline receptors mediate the following effects: increase of glucose-dependent insulin release and transport of glucose into the cells and, as a result, decrease of hyperglycemia, improvement of the

Integrated metabolic flux and omics analysis of Synechocystis sp. PCC 6803 under mixotrophic and photoheterotrophic conditions.

Cyanobacteria have flexible metabolic capability that enables them to adapt to various environments. To investigate their underlying metabolic regulation mechanisms, we performed an integrated analysis of metabolic flux using transcriptomic and metabolomic data of a cyanobacterium Synechocystis sp. PCC 6803, under mixotrophic and photoheterotrophic conditions. The integrated analysis indicated drastic metabolic flux changes, with much smaller changes in gene expression levels and metabolite concentrations between the conditions, suggesting that the flux change was not caused mainly by the expression levels of the corresponding genes. Under photoheterotrophic conditions, created by the addition of the photosynthesis inhibitor atrazine in mixotrophic conditions, the result of metabolic flux analysis indicated the significant repression of carbon fixation and the activation of the oxidative pentose phosphate pathway (PPP). Moreover, we observed gluconeogenic activity of upstream of glycolysis, which enhanced the flux of the oxidative PPP to compensate for NADPH depletion due to the inhibition of the light reaction of photosynthesis. 'Omics' data suggested that these changes were probably caused by the repression of the gap1 gene, which functions as a control valve in the metabolic network. Since metabolic flux is the outcome of a complicated interplay of cellular components, integrating metabolic flux with other 'omics' layers can identify metabolic changes and narrow down these regulatory mechanisms more effectively.

Metabolic regulation of stem cell function

Stem cell function is regulated by intrinsic mechanisms, such as transcriptional and epigenetic regulators, as well as extrinsic mechanisms, such as short-range signals from the niche and long-range humoral signals. Interactions between these regulatory mechanisms and cellular metabolism are just beginning to be identified. In multiple systems, differentiation is accompanied by changes in glycolysis, oxidative phosphorylation and the levels of reactive oxygen species. Indeed, metabolic pathways regulate proliferation and differentiation by regulating energy production and the generation of substrates for biosynthetic pathways. Some metabolic pathways appear to function differently in stem cells as compared with restricted progenitors and differentiated cells. They also appear to influence stem cell function by regulating signal transduction, epigenetic marks and oxidative stress. Studies to date illustrate the importance of metabolism in the regulation of stem cell function and suggest complex cross-regulation likely exists between metabolism and other stem cell regulatory mechanisms.

Lipopolysaccharide-regulated production of bone sialoprotein and interleukin-8 in human periodontal ligament fibroblasts: the role of toll-like receptors 2 and 4 and the MAPK pathway.

Lipopolysaccharide (LPS) on the cell wall of periodontal pathogens is a major mediator of the inflammatory response and can enhance alveolar bone resorption in periodontitis. Bone sialoprotein is an early marker of osteoblast differentiation. The proinflammatory cytokine, interleukin-8 (IL-8), induces osteoclast differentiation, maturation and maintenance of bone resorption activity. However, the effects of LPS from periodontal pathogens on the expression of bone sialoprotein and IL-8 in human osteoblasts and the mechanism of periodontal bone metabolism regulation are rather unclear. The objectives of this study were to determine the effects of Porphyromonas gingivalis LPS on the production of bone sialoprotein and IL-8 in human periodontal ligament fibroblasts (hPDLFs), and to investigate whether toll-like receptor (TLR) 2, TLR4 and MAPKs pathways are involved in the regulation of production of bone sialoprotein and IL-8 by P.gingivalis LPS. The third-generation of hPDLFs were cultured with mineralization-inducing culture medium. After hPDLFs were treated with P.gingivalis LPS, bone sialoprotein and IL-8 mRNA expression were detected using Real time PCR. Then hPDLFs were transiently transfected with siTLR2 or siTLR4 (20nm) or inhibited by MAPK signaling pathways inhibitors, and then bone sialoprotein and IL-8 mRNA and protein expression were also detected using Real time PCR and western blotting. Treatments with 0.01 and 0.1mg/L of P.gingivalis LPS for 8h up-regulated bone sialoprotein mRNA expression, whereas 10 and 100mg/L of P.gingivalis LPS induced a significant decrease in the expression of bone sialoprotein mRNA. In contrast, IL8 mRNA levels were increased significantly by 10mg/L of P.gingivalis LPS. Interestingly, small interfering RNA (siRNA) knock down of the TLR2 and ERK1/2 inhibitor, PD98059, abolished the effects of P.gingivalis LPS on the bone sialoprotein mRNA level, whereas siRNA knock down of the TLR2 and p38 MAPK inhibitor, SB203580, blocked the effect of P.gingivalis LPS on IL-8 in hPDLFs. This study suggests that in hPDLFs, P.gingivalis LPS suppresses bone sialoprotein and enhances IL-8 gene and protein expression via TLR2 and ERK1/2 or the p38 MAPK signaling pathway, respectively.