Increased M2 Isoform of Pyruvate Kinase in Fibroblasts Contributes to the Growth, Aggressiveness, and Osteoclastogenesis of Odontogenic Keratocysts.

To investigate the role of glycolysis and the M2 isoform of pyruvate kinase (PKM2) in odontogenic keratocysts (OKCs), the glycolytic flux of primary odontogenic keratocyst fibroblasts (OKC-Fs) and normal oral mucosa fibroblasts (OM-Fs) was determined by glucose uptake, lactate production, and cell proliferation assays. Wound healing assay and Matrigel-coated chamber system were used to investigate the effects of PKM2 on migration and invasion capacities of OKC-Fs. Co-culture of OKC-Fs with osteoclast precursors (RAW264.7 cells) was used to clarify the role of glycolysis in the osteoclastogenic effects of OKC-Fs. In addition, hypoxia-inducible factor 1α and some key enzymes related to glycolysis, including PKM2, 6-phosphofructo-2-kinase/fructose-2, 6-biphosphatase 3, hexokinase 2, and lactate dehydrogenase A, were detected to assess the activation of glycolysis in OKC stroma by immunohistochemistry. Results showed that the glucose uptake and lactate production were significantly higher in OKC-Fs than OM-Fs. PKM2 was elevated in OKC-Fs compared with that in OM-Fs. PKM2 significantly regulated glycolysis, proliferation, migration, invasion, and osteoclastogenic effects of OKC-Fs. Additionally hypoxia-inducible factor 1α, 6-phosphofructo-2-kinase/fructose-2, 6-biphosphatase 3, hexokinase 2, and lactate dehydrogenase A were markedly overexpressed in OKC stroma, and correlated with PKM2. Moreover, the expression of PKM2 was regulated by oxygen concentration in vitro. In sum, PKM2-mediated glycolysis regulated the growth, aggressiveness, and osteoclastogenesis of OKC.

Discovery, validation, and diagnostic ability of multiple protein-based biomarkers in saliva and gingival crevicular fluid to distinguish between health and periodontal diseases.

AIM: To discover and validate differential protein biomarker expression in saliva and gingival crevicular fluid (GCF) to discriminate objectively between periodontal health and plaque-induced periodontal disease states. MATERIALS AND METHODS: One-hundred and ninety participants were recruited from two centres (Birmingham and Newcastle upon Tyne, UK) comprising healthy, gingivitis, periodontitis, and edentulous donors. Samples from the Birmingham cohort were analysed by quantitative mass spectrometry proteomics for biomarker discovery. Shortlisted candidate proteins were then verified by enzyme-linked immunosorbent assay in both cohorts. Leave-one-out cross validation logistic regression analysis was used to identify the best performing biomarker panels. RESULTS: Ninety-five proteins were identified in both GCF and saliva samples, and 15 candidate proteins were selected based upon differences discovered between the donor groups. The best performing panels to distinguish between: health or gingivitis and periodontitis contained matrix metalloproteinase-9 (MMP9), S100A8, alpha-1-acid glycoprotein (A1AGP), pyruvate kinase, and age (area under the curve [AUC] 0.970); health and gingivitis contained MMP9, S100A8, A1AGP, and pyruvate kinase, but not age (AUC 0.768); and mild to moderate and advanced periodontitis contained MMP9, S100A8, A1AGP, pyruvate kinase, and age (AUC 0.789). CONCLUSIONS: Biomarker panels containing four proteins with and without age as a further parameter can distinguish between periodontal health and disease states.

Effect of free and nano-encapsulated curcumin on treatment and energetic metabolism of gerbils infected by Listeria monocytogenes.

Bacterial infections require special care since the indiscriminate use of antibiotics to treat them has been linked to the emergence of resistant strains. In this sense, phytoterapeutic alternatives such as curcumin and its nanocapsules have emerged as a promising supplement in optimizing availability of bioactives and reducing the development of antimicrobial resistance. Thus, the aim of this study was to verify the effects of pure and nanoencapsulated curcumin in the treatment of experimental listeriosis in gerbils regarding many aspects including antibacterial effect, antioxidant mechanisms involved and the energetic metabolism. Four groups were used containing 6 animals each: T0 (control), T1 (infected), T2 (infected and treated with free curcumin - dose of 30 mg/kg/day) and T3 (infected and treated with nanocapsules containing curcumin - a dose of 3 mg/kg/day). Treated animals received curcumin for 6 consecutive days starting 24 h after Listeria monocytogenes infection. All animals were euthanized on the 12th day after L. monocytogenes infection. Quantitative polymerase chain reaction (qPCR) identified L. monocytogenes DNA in the spleens of all animals of the T1 group, as well as T2 (2 out of 6) and T3 (5 out of 6). The weight of the spleens confirmed the infection, since it was larger in the T1 group, differing statistically from T0, and similarly to T2 and T3. Hepatic histopathological examination showed mild infiltration of neutrophils and macrophages, except for the T3 group (only 1/6). In the liver, the pyruvate kinase activity was higher in T1 and T2 compared to T0 and T3. The adenylate kinase activity did not differ between groups. The Na+/K+ATPase activity was lower in T1 group compared to T0 and T3. Lipoperoxidation was lower in the T3 group compared to groups T0, T1 and T2. The antioxidant capacity against peroxyl radicals was higher in T1, T2 and T3 groups compared to T0. In conclusion, free curcumin showed potent antibacterial effects; however, the nanoencapsulated form was able to minimize the effects caused by L. monocytogenes regarding tissue injury, changes on enzymes of the energetic metabolism, in addition to an antioxidant effect against lipoperoxidation.

Bienzymatic Sequential Reaction on Microgel Particles and Their Cofactor Dependent Applications.

We report, the preparation and characterization of bioconjugates, wherein enzymes pyruvate kinase (Pk) and l-lactic dehydrogenase (Ldh) were covalently bound to poly(N-isopropylacrylamide)-poly(ethylenimine) (PNIPAm-PEI) microgel support using glutaraldehyde (GA) as the cross-linker. The effects of different arrangements of enzymes on the microgels were investigated for the enzymatic behavior and to obtain maximum Pk-Ldh sequential reaction. The dual enzyme bioconjugates prepared by simultaneous addition of both the enzymes immobilized on the same microgel particles (PL), and PiLi, that is, dual enzyme bioconjugate obtained by combining single-enzyme bioconjugates (immobilized pyruvate kinase (Pi) and immobilized lactate dehydrogenase (Li)), were used to study the effect of the assembly of dual enzymes systems on the microgels. The kinetic parameters (Km, kcat), reaction parameters (temperature, pH), stability (thermal and storage), and cofactor dependent applications were studied for the dual enzymes conjugates. The kinetic results indicated an improved turn over number (kcat) for PL, while the kcat and catalytic efficiency was significantly decreased in case of PiLi. For cofactor dependent application, in which the ability of ADP monitoring and ATP synthesis by the conjugates were studied, the activity of PL was found to be nearly 2-fold better than that of PiLi. These results indicated that the influence of spacing between the enzymes is an important factor in optimization of multienzyme immobilization on the support.

Glycometabolic reprogramming associated with the initiation of human dental pulp stem cell differentiation.

Glycometabolism, particularly mitochondrial oxidative phosphorylation (OXPHOS) and glycolysis, plays a central role in cell life activities. Glycometabolism can be reprogrammed to maintain the stemness or to induce the differentiation of stem cells, thereby regulating tissue repair and regeneration. However, research on the glycometabolism of human dental pulp stem cells (hDPSCs) remains scarce. Here, we investigated the relationship between glycometabolic reprogramming and initiation of hDPSC differentiation. We found the differentiation of hDPSCs commenced on day 3 when cells were cultured in mineralized medium. When cell differentiation commenced, mitochondria became elongated with well-developed cristae, and the oxygen consumption rate of mitochondria was enhanced, manifested as an increase in basal respiration, mitochondrial ATP production, and maximal respiration. Interestingly, glycolytic enzyme activities, glycolysis capacity, and glycolysis reserve were also upregulated at this time to match the powerful bioenergetic demands. More importantly, hDPSCs derived from different donors or cultured in various oxygen environments showed similar glycometabolic changes when they began to differentiate. Thus, glycometabolic reprogramming accompanies initiation of hDPSC differentiation and could potentially play a role in the regulation of dental pulp repair.

[THE BIOCHEMICAL AND PATHOPHYSIOLOGICAL MARKERS OF CHEMICAL EFFECT ON ORGANISM, THEIR INFORMATIVENESS AND DIAGNOSTIC SIGNIFICANCE].

The sampling of study included 185 examined workers. Out of them 90 work at "Opitnii zavod Neftekhim" (67 females and 23 males) and 95--at "Kaustik" (64 females and 31 males) from various workshops of the given enterprises. To determine biochemical indicators samples of blood, saliva and urine were collected. The study was carried out in concordance with ethic principles of the Helsinki world medical association declaration, 2008 ed. with receiving written consent of patient to participate in study.

Pyruvate kinase M2 activators promote tetramer formation and suppress tumorigenesis.

Cancer cells engage in a metabolic program to enhance biosynthesis and support cell proliferation. The regulatory properties of pyruvate kinase M2 (PKM2) influence altered glucose metabolism in cancer. The interaction of PKM2 with phosphotyrosine-containing proteins inhibits enzyme activity and increases the availability of glycolytic metabolites to support cell proliferation. This suggests that high pyruvate kinase activity may suppress tumor growth. We show that expression of PKM1, the pyruvate kinase isoform with high constitutive activity, or exposure to published small-molecule PKM2 activators inhibits the growth of xenograft tumors. Structural studies reveal that small-molecule activators bind PKM2 at the subunit interaction interface, a site that is distinct from that of the endogenous activator fructose-1,6-bisphosphate (FBP). However, unlike FBP, binding of activators to PKM2 promotes a constitutively active enzyme state that is resistant to inhibition by tyrosine-phosphorylated proteins. These data support the notion that small-molecule activation of PKM2 can interfere with anabolic metabolism.

Redirecting carbon flux through exogenous pyruvate kinase to achieve high ethanol yields in Clostridium thermocellum.

In Clostridium thermocellum, a thermophilic anaerobic bacterium able to rapidly ferment cellulose to ethanol, pyruvate kinase (EC 2.7.1.40) is absent based on both the genome sequence and enzymatic assays. Instead, a new pathway converting phosphoenolpyruvate to pyruvate via a three-step pathway involving phosphoenolpyruvate carboxykinase, NADH-linked malate dehydrogenase, and NADP-dependent malic enzyme has been found. We examined the impact of targeted modification of enzymes associated with this pathway, termed the "malate shunt", including expression of the pyruvate kinase gene from Thermoanaerobacterium saccharolyticum, mutation of the phosphoenolpyruvate carboxykinase and deletion of malic enzyme gene. Strain YD01 with exogenous pyruvate kinase, in which phosphoenolpyruvate carboxykinase expression was diminished by modifying the start codon from ATG to GTG, exhibited 3.25-fold higher ethanol yield than the wild-type strain. A second strain, YD02 with exogenous pyruvate kinase, in which the gene for malic enzyme and part of malate dehydrogenase were deleted, had over 3-fold higher ethanol yield than the wild-type strain.

Unraveling the metabolism of Mycobacterium caprae using comparative genomics.

In our laboratory, Mycobacterium caprae has poor growth in standard medium (SM) 7H9-OADC supplemented with pyruvate and Tween-80. Our objectives were to identify mutations affecting M. caprae metabolism and use this information to design a culture medium to improve its growth. We selected 77 M. caprae genomes and sequenced M. caprae NLA000201913 used in our experiments. Mutations present in >95% of the strains compared to Mycobacterium tuberculosis H37Rv were analyzed in silico for their deleterious effects on proteins of metabolic pathways. Apart from the known defect in the pyruvate kinase, M. caprae has important lesions in enzymes of the TCA cycle, methylmalonyl cycle, B12 metabolism, and electron-transport chain. We provide evidence of enzymatic redundancy elimination and epistatic mutations, and possible production of toxic metabolites hindering M. caprae growth in vitro. A newly designed SM supplemented with l-glutamate allowed faster growth and increased final microbial mass of M. caprae. However, possible accumulation of metabolic waste-products and/or nutritional limitations halted M. caprae growth prior to a M. tuberculosis-like stationary phase. Our findings suggest that M. caprae relies on GABA and/or glyoxylate shunts for in vitro growth in routine media. The newly developed medium will improve experiments with this bacterium by allowing faster growth in vitro.

Expressions of GLUT-1, PK-M2 and HIF-1α and Mutation Status of BRAF in Odontogenic Keratocysts.

OBJECTIVE: To investigate the expressions and clinicopathological features of glucose transporter 1 (GLUT-1), pyruvate kinase M2 (PK-M2) and hypoxia-inducible factor 1α (HIF-1α) in odontogenic keratocysts (OKCs), and to investigate the mutation status of v-raf murine sarcoma viral oncogene homolog B1 (BRAF). METHODS: Following a retrospective review of the clinicopathological data of 28 OKC cases, the expressions of GLUT-1, PK-M2 and HIF-1α in these tissue samples were detected through immunohistochemistry. The BRAF mutation statuses of all cases were examined using polymerase chain reaction amplification and direct sequencing. RESULTS: The expression levels of HIF-1α varied in 96.4% of OKC tissues, and there were higher positive rates of PKM2 (100%) and GLUT-1 (100%) in these tissues. None of the 28 OKC samples carried the BRAF mutation. CONCLUSION: The positive expressions of GLUT-1, PK-M2 and HIF-1α indicate that patients with OKCs undergo anaerobic glycolysis to a certain extent, but these processes appear to be irrelevant to clinicopathological features and to the BRAF mutation.