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Results: 1 to 10 of 112

Publication Record


Discovery and characterization of N-(1,3-dialkyl-1H-indazol-6-yl)-1H-pyrazolo[4,3-b]pyridin-3-amine scaffold as mGlu positive allosteric modulators that mitigate CYP1A2 induction liability.
Engers DW, Bollinger SR, Engers JL, Panarese JD, Breiner MM, Gregro A, Blobaum AL, Bronson JJ, Wu YJ, Macor JE, Rodriguez AL, Zamorano R, Conn PJ, Lindsley CW, Niswender CM, Hopkins CR
(2018) Bioorg Med Chem Lett 28: 2641-2646
MeSH Terms: Allosteric Regulation, Animals, Antiparkinson Agents, Cytochrome P-450 CYP1A2, Cytochrome P-450 CYP1A2 Inducers, Drug Discovery, Enzyme Induction, Humans, Pyrazoles, Pyridines, Rats, Receptors, Metabotropic Glutamate, Structure-Activity Relationship
Show Abstract · Added March 3, 2020
Previous reports from our laboratory disclosed the structure and activity of a novel 1H-pyrazolo[4,3-b]pyridine-3-amine scaffold (VU8506) which showed excellent potency, selectivity and in vivo efficacy in preclinical rodent models of Parkinson's disease. Unfortunately, this compound suffered from significant CYP1A2 induction as measured through upstream AhR activation (125-fold) and thus was precluded from further advancement in chronic studies. Herein, we report a new scaffold developed recently which was systematically studied in order to mitigate the CYP1A2 liabilities presented in the earlier scaffolds. We have identified a novel structure that maintains the potency and selectivity of other mGlu PAMs, leading to 9i (hmGlu EC = 43 nM; AhR activation = 2.3-fold).
Copyright © 2018 Elsevier Ltd. All rights reserved.
0 Communities
1 Members
0 Resources
MeSH Terms
Induction of human cytochrome P450 3A enzymes in cultured placental cells by thalidomide and relevance to bioactivation and toxicity.
Murayama N, Kazuki Y, Satoh D, Arata K, Harada T, Shibata N, Guengerich FP, Yamazaki H
(2017) J Toxicol Sci 42: 343-348
MeSH Terms: Cells, Cultured, Cytochrome P-450 CYP3A, Enzyme Induction, Female, Humans, Liver, Oxidation-Reduction, Placenta, Pregnancy, Pregnane X Receptor, RNA, Messenger, Receptors, Steroid, Rifampin, Thalidomide
Show Abstract · Added March 14, 2018
Evidence has been presented for auto-induced human cytochrome P450 3A enzyme involvement in the teratogenicity and clinical outcome of thalidomide due to oxidation to 5-hydroxythalidomide and subsequent metabolic activation in livers. In this study, more relevant human placenta preparations and placental BeWo cells showed low but detectable P450 3A4/5 mRNA expression and drug oxidation activities. Human placental microsomal fractions from three subjects showed detectable midazolam 1´- and 4-hydroxylation and thalidomide 5-hydroxylation activities. Human placental BeWo cells, cultured in the recommended media, also indicated detectable midazolam 1´- and 4-hydroxylation and thalidomide 5-hydroxylation activities. To reduce any masking effects by endogenous hormones used in the recommended media, induction of P450 3A4/5 mRNA and oxidation activities were measured in placental BeWo cells cultured with a modified medium containing 5% charcoal-stripped fetal bovine serum. Thalidomide significantly induced P450 3A4/5, 2B6, and pregnane X receptor (PXR) mRNA levels 2 to 3-fold, but rifampicin only enhanced P450 3A5 and PXR mRNA under the modified media conditions. Under these modified conditions, thalidomide also significantly induced midazolam 1´-hydroxylation and thalidomide 5-hydroxylaion activities 3-fold but not bupropion hydroxylation activity. Taken together, activation of thalidomide to 5-hydroxythalidomide with autoinduction of P450 3A enzymes in human placentas, as well as livers, is suggested in vivo.
0 Communities
1 Members
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14 MeSH Terms
Increased Helicobacter pylori-associated gastric cancer risk in the Andean region of Colombia is mediated by spermine oxidase.
Chaturvedi R, de Sablet T, Asim M, Piazuelo MB, Barry DP, Verriere TG, Sierra JC, Hardbower DM, Delgado AG, Schneider BG, Israel DA, Romero-Gallo J, Nagy TA, Morgan DR, Murray-Stewart T, Bravo LE, Peek RM, Fox JG, Woster PM, Casero RA, Correa P, Wilson KT
(2015) Oncogene 34: 3429-40
MeSH Terms: Adenocarcinoma, Adult, Animals, Cells, Cultured, Colombia, DNA Damage, Enzyme Induction, Gerbillinae, Helicobacter Infections, Helicobacter pylori, Humans, Hydrogen Peroxide, Male, Middle Aged, Oxidative Stress, Oxidoreductases Acting on CH-NH Group Donors, Risk Factors, Stomach Neoplasms
Show Abstract · Added January 20, 2015
Helicobacter pylori infection causes gastric cancer, the third leading cause of cancer death worldwide. More than half of the world's population is infected, making universal eradication impractical. Clinical trials suggest that antibiotic treatment only reduces gastric cancer risk in patients with non-atrophic gastritis (NAG), and is ineffective once preneoplastic lesions of multifocal atrophic gastritis (MAG) and intestinal metaplasia (IM) have occurred. Therefore, additional strategies for risk stratification and chemoprevention of gastric cancer are needed. We have implicated polyamines, generated by the rate-limiting enzyme ornithine decarboxylase (ODC), in gastric carcinogenesis. During H. pylori infection, the enzyme spermine oxidase (SMOX) is induced, which generates hydrogen peroxide from the catabolism of the polyamine spermine. Herein, we assessed the role of SMOX in the increased gastric cancer risk in Colombia associated with the Andean mountain region when compared with the low-risk region on the Pacific coast. When cocultured with gastric epithelial cells, clinical strains of H. pylori from the high-risk region induced more SMOX expression and oxidative DNA damage, and less apoptosis than low-risk strains. These findings were not attributable to differences in the cytotoxin-associated gene A oncoprotein. Gastric tissues from subjects from the high-risk region exhibited greater levels of SMOX and oxidative DNA damage by immunohistochemistry and flow cytometry, and this occurred in NAG, MAG and IM. In Mongolian gerbils, a prototype colonizing strain from the high-risk region induced more SMOX, DNA damage, dysplasia and adenocarcinoma than a colonizing strain from the low-risk region. Treatment of gerbils with either α-difluoromethylornithine, an inhibitor of ODC, or MDL 72527 (N(1),N(4)-Di(buta-2,3-dien-1-yl)butane-1,4-diamine dihydrochloride), an inhibitor of SMOX, reduced gastric dysplasia and carcinoma, as well as apoptosis-resistant cells with DNA damage. These data indicate that aberrant activation of polyamine-driven oxidative stress is a marker of gastric cancer risk and a target for chemoprevention.
0 Communities
6 Members
0 Resources
18 MeSH Terms
Activation of MAPK and FoxO by manganese (Mn) in rat neonatal primary astrocyte cultures.
Exil V, Ping L, Yu Y, Chakraborty S, Caito SW, Wells KS, Karki P, Lee E, Aschner M
(2014) PLoS One 9: e94753
MeSH Terms: Active Transport, Cell Nucleus, Animals, Animals, Newborn, Astrocytes, Cell Nucleus, Cells, Cultured, Enzyme Activation, Enzyme Induction, Forkhead Box Protein O3, Forkhead Transcription Factors, Manganese, Mitogen-Activated Protein Kinases, Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha, Phosphorylation, Proto-Oncogene Proteins c-akt, Pyrrolidonecarboxylic Acid, Rats, Rats, Sprague-Dawley, Reactive Oxygen Species, Signal Transduction, Superoxide Dismutase, Thiazolidines, Time Factors, Transcription Factors
Show Abstract · Added April 11, 2016
Environmental exposure to manganese (Mn) leads to a neurodegenerative disease that has shared clinical characteristics with Parkinson's disease (PD). Mn-induced neurotoxicity is time- and dose-dependent, due in part to oxidative stress. We ascertained the molecular targets involved in Mn-induced neurodegeneration using astrocyte culture as: (1) Astrocytes are vital for information processing within the brain, (2) their redox potential is essential in mitigating reactive oxygen species (ROS) levels, and (3) they are targeted early in the course of Mn toxicity. We first tested protein levels of Mn superoxide dismutase -2 (SOD-2) and glutathione peroxidase (GPx-1) as surrogates of astrocytic oxidative stress response. We assessed levels of the forkhead winged-helix transcription factor O (FoxO) in response to Mn exposure. FoxO is highly regulated by the insulin-signaling pathway. FoxO mediates cellular responses to toxic stress and modulates adaptive responses. We hypothesized that FoxO is fundamental in mediating oxidative stress response upon Mn treatment, and may be a biomarker of Mn-induced neurodegeneration. Our results indicate that 100 or 500 µM of MnCl2 led to increased levels of FoxO (dephosphorylated and phosphorylated) compared with control cells (P<0.01). p-FoxO disappeared from the cytosol upon Mn exposure. Pre-treatment of cultured cells with (R)-(-)-2-oxothiazolidine-4-carboxylic acid (OTC), a cysteine analog rescued the cytosolic FoxO. At these concentrations, MAPK phosphorylation, in particular p38 and ERK, and PPAR gamma coactivator-1 (PGC-1) levels were increased, while AKT phosphorylation remained unchanged. FoxO phosphorylation level was markedly reduced with the use of SB203580 (a p38 MAPK inhibitor) and PD98059 (an ERK inhibitor). We conclude that FoxO phosphorylation after Mn exposure occurs in parallel with, and independent of the insulin-signaling pathway. FoxO levels and its translocation into the nucleus are part of early events compensating for Mn-induced neurotoxicity and may serve as valuable targets for neuroprotection in the setting of Mn-induced neurodegeneration.
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1 Members
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24 MeSH Terms
Type 2 diabetes and congenital hyperinsulinism cause DNA double-strand breaks and p53 activity in β cells.
Tornovsky-Babeay S, Dadon D, Ziv O, Tzipilevich E, Kadosh T, Schyr-Ben Haroush R, Hija A, Stolovich-Rain M, Furth-Lavi J, Granot Z, Porat S, Philipson LH, Herold KC, Bhatti TR, Stanley C, Ashcroft FM, In't Veld P, Saada A, Magnuson MA, Glaser B, Dor Y
(2014) Cell Metab 19: 109-21
MeSH Terms: Animals, Biomarkers, Calcineurin, Cell Death, Cell Proliferation, Congenital Hyperinsulinism, DNA Breaks, Double-Stranded, Diabetes Mellitus, Type 2, Disease Models, Animal, Enzyme Activation, Enzyme Induction, Fasting, Glucagon-Like Peptide 1, Glucokinase, Glucose, Humans, Insulin-Secreting Cells, Membrane Potentials, Mice, Transgenes, Tumor Suppressor Protein p53
Show Abstract · Added February 11, 2014
β cell failure in type 2 diabetes (T2D) is associated with hyperglycemia, but the mechanisms are not fully understood. Congenital hyperinsulinism caused by glucokinase mutations (GCK-CHI) is associated with β cell replication and apoptosis. Here, we show that genetic activation of β cell glucokinase, initially triggering replication, causes apoptosis associated with DNA double-strand breaks and activation of the tumor suppressor p53. ATP-sensitive potassium channels (KATP channels) and calcineurin mediate this toxic effect. Toxicity of long-term glucokinase overactivity was confirmed by finding late-onset diabetes in older members of a GCK-CHI family. Glucagon-like peptide-1 (GLP-1) mimetic treatment or p53 deletion rescues β cells from glucokinase-induced death, but only GLP-1 analog rescues β cell function. DNA damage and p53 activity in T2D suggest shared mechanisms of β cell failure in hyperglycemia and CHI. Our results reveal membrane depolarization via KATP channels, calcineurin signaling, DNA breaks, and p53 as determinants of β cell glucotoxicity and suggest pharmacological approaches to enhance β cell survival in diabetes.
Copyright © 2014 Elsevier Inc. All rights reserved.
2 Communities
1 Members
1 Resources
21 MeSH Terms
Alkaline phosphatases contribute to uterine receptivity, implantation, decidualization, and defense against bacterial endotoxin in hamsters.
Lei W, Nguyen H, Brown N, Ni H, Kiffer-Moreira T, Reese J, Millán JL, Paria BC
(2013) Reproduction 146: 419-32
MeSH Terms: Alkaline Phosphatase, Animals, Cricetinae, Decidua, Embryo Implantation, Endometrium, Enzyme Induction, Escherichia coli Infections, Estrous Cycle, Female, Immunity, Innate, Isoenzymes, Lipopolysaccharides, Mesocricetus, Ovariectomy, Phosphorylation, Placentation, Pregnancy, RNA, Messenger, Uterus
Show Abstract · Added April 9, 2015
Alkaline phosphatase (AP) activity has been demonstrated in the uterus of several species, but its importance in the uterus, in general and during pregnancy, is yet to be revealed. In this study, we focused on identifying AP isozyme types and their hormonal regulation, cell type, and event-specific expression and possible functions in the hamster uterus during the cycle and early pregnancy. Our RT-PCR and in situ hybridization studies demonstrated that among the known Akp2, Akp3, Akp5, and Akp6 murine AP isozyme genes, hamster uteri express only Akp2 and Akp6; both genes are co-expressed in luminal epithelial cells. Studies in cyclic and ovariectomized hamsters established that while progesterone (P₄) is the major uterine Akp2 inducer, both P₄ and estrogen are strong Akp6 regulators. Studies in preimplantation uteri showed induction of both genes and the activity of their encoded isozymes in luminal epithelial cells during uterine receptivity. However, at the beginning of implantation, Akp2 showed reduced expression in luminal epithelial cells surrounding the implanted embryo. By contrast, expression of Akp6 and its isozyme was maintained in luminal epithelial cells adjacent to, but not away from, the implanted embryo. Following implantation, stromal transformation to decidua was associated with induced expressions of only Akp2 and its isozyme. We next demonstrated that uterine APs dephosphorylate and detoxify endotoxin lipopolysaccharide at their sites of production and activity. Taken together, our findings suggest that uterine APs contribute to uterine receptivity, implantation, and decidualization in addition to their role in protection of the uterus and pregnancy against bacterial infection.
0 Communities
1 Members
0 Resources
20 MeSH Terms
Increased dietary sodium induces COX2 expression by activating NFκB in renal medullary interstitial cells.
He W, Zhang M, Zhao M, Davis LS, Blackwell TS, Yull F, Breyer MD, Hao CM
(2014) Pflugers Arch 466: 357-367
MeSH Terms: Animals, Benzamides, Cyclooxygenase 2, Enzyme Induction, Kidney Medulla, Male, Mice, Mice, Inbred C57BL, NF-kappa B, Sodium, Sodium Chloride, Dietary
Show Abstract · Added March 7, 2014
High salt diet induces renal medullary cyclooxygenase 2 (COX2) expression. Selective blockade of renal medullary COX2 activity in rats causes salt-sensitive hypertension, suggesting a role for renal medullary COX2 in maintaining systemic sodium balance. The present study characterized the cellular location of COX2 induction in the kidney of mice following high salt diet and examined the role of NFκB in mediating this COX2 induction in response to increased dietary salt. High salt diet (8 % NaCl) for 3 days markedly increased renal medullary COX2 expression in C57Bl/6 J mice. Co-immunofluorescence using a COX2 antibody and antibodies against aquaporin-2, ClC-K, aquaporin-1, and CD31 showed that high salt diet-induced COX2 was selectively expressed in renal medullary interstitial cells. By using NFκB reporter transgenic mice, we observed a sevenfold increase of luciferase activity in the renal medulla of the NFκB-luciferase reporter mice following high salt diet, and a robust induction of enhanced green fluorescent protein (EGFP) expression mainly in renal medullary interstitial cells of the NFκB-EGFP reporter mice following high salt diet. Treating high salt diet-fed C57Bl/6 J mice with selective IκB kinase inhibitor IMD-0354 (8 mg/kg bw) substantially suppressed COX2 induction in renal medulla, and also significantly reduced urinary prostaglandin E2 (PGE2). These data therefore suggest that renal medullary interstitial cell NFκB plays an important role in mediating renal medullary COX2 expression and promoting renal PGE2 synthesis in response to increased dietary sodium.
1 Communities
2 Members
0 Resources
11 MeSH Terms
β-Cell-specific protein kinase A activation enhances the efficiency of glucose control by increasing acute-phase insulin secretion.
Kaihara KA, Dickson LM, Jacobson DA, Tamarina N, Roe MW, Philipson LH, Wicksteed B
(2013) Diabetes 62: 1527-36
MeSH Terms: Animals, Crosses, Genetic, Cyclic AMP, Cyclic AMP-Dependent Protein Kinases, Enzyme Induction, Exenatide, Glucose Clamp Technique, Hyperglycemia, Hypoglycemic Agents, Insulin, Insulin Secretion, Insulin-Secreting Cells, Kinetics, Mice, Mutant Proteins, Patch-Clamp Techniques, Peptides, Phosphorylation, Protein Processing, Post-Translational, Protein Subunits, Second Messenger Systems, Up-Regulation, Venoms
Show Abstract · Added February 12, 2015
Acute insulin secretion determines the efficiency of glucose clearance. Moreover, impaired acute insulin release is characteristic of reduced glucose control in the prediabetic state. Incretin hormones, which increase β-cell cAMP, restore acute-phase insulin secretion and improve glucose control. To determine the physiological role of the cAMP-dependent protein kinase (PKA), a mouse model was developed to increase PKA activity specifically in the pancreatic β-cells. In response to sustained hyperglycemia, PKA activity potentiated both acute and sustained insulin release. In contrast, a glucose bolus enhanced acute-phase insulin secretion alone. Acute-phase insulin secretion was increased 3.5-fold, reducing circulating glucose to 58% of levels in controls. Exendin-4 increased acute-phase insulin release to a similar degree as PKA activation. However, incretins did not augment the effects of PKA on acute-phase insulin secretion, consistent with incretins acting primarily via PKA to potentiate acute-phase insulin secretion. Intracellular calcium signaling was unaffected by PKA activation, suggesting that the effects of PKA on acute-phase insulin secretion are mediated by the phosphorylation of proteins involved in β-cell exocytosis. Thus, β-cell PKA activity transduces the cAMP signal to dramatically increase acute-phase insulin secretion, thereby enhancing the efficiency of insulin to control circulating glucose.
0 Communities
1 Members
0 Resources
23 MeSH Terms
Brain-selective overexpression of angiotensin-converting enzyme 2 attenuates sympathetic nerve activity and enhances baroreflex function in chronic heart failure.
Xiao L, Gao L, Lazartigues E, Zucker IH
(2011) Hypertension 58: 1057-65
MeSH Terms: Angiotensin I, Angiotensin II, Angiotensin-Converting Enzyme 2, Animals, Baroreflex, Enzyme Induction, Heart Failure, Humans, Male, Medulla Oblongata, Mice, Mice, Knockout, Myocardial Ischemia, Nerve Tissue Proteins, Nitric Oxide, Norepinephrine, Organ Specificity, Peptide Fragments, Peptidyl-Dipeptidase A, Proto-Oncogene Proteins, Receptors, Angiotensin, Receptors, G-Protein-Coupled, Recombinant Fusion Proteins, Reflex, Abnormal, Sympathetic Nervous System
Show Abstract · Added August 5, 2014
Angiotensin-converting enzyme 2 (ACE2) has been suggested to be involved in the central regulation of autonomic function. During chronic heart failure (CHF), elevated central angiotensin II signaling contributes to the sustained increase of sympathetic outflow. This is accompanied by a downregulation of ACE2 in the brain. We hypothesized that central overexpression of ACE2 decreases sympathetic outflow and enhances baroreflex function in CHF. Transgenic mice overexpressing human ACE2 selectively in the brain (SYN-hACE2 [SA]) and wild-type littermates (WT) were used. CHF was induced by permanent coronary artery ligation. Four weeks after coronary artery ligation, both WT and SA mice exhibited a significant decrease in left ventricular ejection fraction (<40%). A slight decrease in mean arterial pressure was found only in SA mice. Compared with WT mice with CHF, brain-selective ACE2 overexpression attenuated left ventricular end-diastolic pressure; decreased urinary norepinephrine excretion; baseline renal sympathetic nerve activity (WT CHF: 71.6±7.6% max versus SA CHF: 49.3±6.1% max); and enhanced baroreflex sensitivity (maximum slope: WT sham: 1.61±0.16%/mm Hg versus SA CHF: 1.51±0.17%/mm Hg). Chronic subcutaneous blockade of mas receptor increased renal sympathetic nerve activity in SA mice with CHF (A779: 67.3±5.8% versus vehicle: 46.4±3.6% of max). An upregulation in angiotensin II type 1 receptor expression was detected in medullary nuclei in WT CHF mice, which was significantly attenuated in SA mice with CHF. These data suggest that central ACE2 overexpression exerts a potential protective effect in CHF through attenuating sympathetic outflow. The mechanism for this effect involves angiotensin (1-7) mas signaling, as well as a decrease in angiotensin II type 1 receptor signaling in the medulla.
0 Communities
1 Members
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25 MeSH Terms
Immune evasion by Helicobacter pylori is mediated by induction of macrophage arginase II.
Lewis ND, Asim M, Barry DP, de Sablet T, Singh K, Piazuelo MB, Gobert AP, Chaturvedi R, Wilson KT
(2011) J Immunol 186: 3632-41
MeSH Terms: Animals, Arginase, Disease Models, Animal, Enzyme Induction, Helicobacter Infections, Helicobacter pylori, Immune Evasion, Intestinal Mucosa, Macrophages, Male, Mice, Mice, Inbred C57BL, Mice, Knockout, Nitric Oxide Synthase Type II
Show Abstract · Added March 5, 2014
Helicobacter pylori infection persists for the life of the host due to the failure of the immune response to eradicate the bacterium. Determining how H. pylori escapes the immune response in its gastric niche is clinically important. We have demonstrated in vitro that macrophage NO production can kill H. pylori, but induction of macrophage arginase II (Arg2) inhibits inducible NO synthase (iNOS) translation, causes apoptosis, and restricts bacterial killing. Using a chronic H. pylori infection model, we determined whether Arg2 impairs host defense in vivo. In C57BL/6 mice, expression of Arg2, but not arginase I, was abundant and localized to gastric macrophages. Arg2(-/-) mice had increased histologic gastritis and decreased bacterial colonization compared with wild-type (WT) mice. Increased gastritis scores correlated with decreased colonization in individual Arg2(-/-) mice but not in WT mice. When mice infected with H. pylori were compared, Arg2(-/-) mice had more gastric macrophages, more of these cells were iNOS(+), and these cells expressed higher levels of iNOS protein, as determined by flow cytometry and immunofluorescence microscopy. There was enhanced nitrotyrosine staining in infected Arg2(-/-) versus WT mice, indicating increased NO generation. Infected Arg2(-/-) mice exhibited decreased macrophage apoptosis, as well as enhanced IFN-γ, IL-17a, and IL-12p40 expression, and reduced IL-10 levels consistent with a more vigorous Th1/Th17 response. These studies demonstrate that Arg2 contributes to the immune evasion of H. pylori by limiting macrophage iNOS protein expression and NO production, mediating macrophage apoptosis, and restraining proinflammatory cytokine responses.
0 Communities
3 Members
0 Resources
14 MeSH Terms