Forgot your password?
New user?
New Window Opens on the Secret Life of Microbes: Scientists Develop First Microbial Profiles of Ecosystems
CAS announces the release of SciFinder Scholar for Mac OS X
Press Releases
Press Releases
| Check out our New Publishers' Select for Free Articles |
Biochemical Pharmacology (v.84, #7)
TRPM4 channels in the cardiovascular system: Physiology, pathophysiology, and pharmacology by Hugues Abriel; Ninda Syam; Valentin Sottas; Mohamed Yassine Amarouch; Jean-Sébastien Rougier (pp. 873-881).
The transient receptor potential channel (TRP) family comprises at least 28 genes in the human genome. These channels are widely expressed in many different tissues, including those of the cardiovascular system. The transient receptor potential channel melastatin 4 (TRPM4) is a Ca2+-activated non-specific cationic channel, which is impermeable to Ca2+. TRPM4 is expressed in many cells of the cardiovascular system, such as cardiac cells of the conduction pathway and arterial and venous smooth muscle cells. This review article summarizes the recently described roles of TRPM4 in normal physiology and in various disease states. Genetic variants in the human gene TRPM4 have been linked to several cardiac conduction disorders. TRPM4 has also been proposed to play a crucial role in secondary hemorrhage following spinal cord injuries. Spontaneously hypertensive rats with cardiac hypertrophy were shown to over-express the cardiac TRPM4 channel. Recent studies suggest that TRPM4 plays an important role in cardiovascular physiology and disease, even if most of the molecular and cellular mechanisms have yet to be elucidated. We conclude this review article with a brief overview of the compounds that have been shown to either inhibit or activate TRPM4 under experimental conditions. Based on recent findings, the TRPM4 channel can be proposed as a future target for the pharmacological treatment of cardiovascular disorders, such as hypertension and cardiac arrhythmias.
Keywords: Abbreviations; ATP; adenosine triphosphate; AVB; atrio-ventricular conduction block; CRAC; Ca; 2+; -release-activated Ca; 2+; channel; ICCD; isolated cardiac conduction disease; Orai1; Ca; 2+; release-activated Ca; 2+; channel protein 1; PFHB1; progressive familial heart block type 1; PIP2; phospatidylinositol 4 5-biphosphate; PKC; protein kinase C; PLC; phospholipase C; RBBB; right bundle branch blockTRPM4; Cardiovascular system; Physiology; Channelopathies; Pharmacology
Medication discovery for addiction: Translating the dopamine D3 receptor hypothesis by Amy Hauck Newman; Brandi L. Blaylock; Michael A. Nader; Jack Bergman; David R. Sibley; Phil Skolnick (pp. 882-890).
The dopamine D3 receptor (D3R) has been investigated as a potential target for medication development to treat substance use disorders (SUDs) with a particular focus on cocaine and methamphetamine. Currently, there are no approved medications to treat cocaine and methamphetamine addiction and thus developing pharmacotherapeutics to complement existing behavioral strategies is a fundamental goal. Novel compounds with high affinity and D3R selectivity have been evaluated in numerous animal models of drug abuse and favorable outcomes in nonhuman primate models of self-administration and relapse have provided compelling evidence to advance these agents into the clinic. One approach is to repurpose drugs that share the D3R mechanism and already have clinical utility, and to this end buspirone has been identified as a viable candidate for clinical trials. A second, but substantially more resource intensive and risky approach involves the development of compounds that exclusively target D3R, such as GSK598809 and PG 619. Clinical investigation of these drugs or other novel D3R-selective agents will provide a better understanding of the role D3R plays in addiction and whether or not antagonists or partial agonists that are D3R selective are effective in achieving abstinence in this patient population.
Keywords: Abbreviations; SUD; substance use disorder; CNS; central nervous system; D2R; dopamine D2 receptor; D3R; dopamine D3 receptor; D4R; dopamine D4 receptor; 11; C-PHNO; [; 11; C]-(+)-propyl-3,4,4a,5,6,10b-hexahydro-2H-naphtho[1,2-b]-[1,4]-oxazine-9-ol; ADME; absorption distribution metabolism excretion; AUC; area under the curve; ATDP; Addiction Treatment Discovery Program; CTN; Clinical Trials Network; PET; positron emission tomographyCocaine; Methamphetamine; Buspirone; Psychostimulant abuse; Medication development
Mycoepoxydiene, a fungal polyketide inhibits MCF-7 cells through simultaneously targeting p53 and NF-κB pathways by Jifeng Wang; Baobing Zhao; Yuting Yi; Wei Zhang; Xuan Wu; Lianru Zhang; Yuemao Shen (pp. 891-899).
Mycoepoxydiene (MED) is a cytotoxic polyketide that is isolated from the marine fungal strain Diaporthe sp. HLY-1, which is associated with mangroves; however, the mechanism of action of MED remains unknown. Here, we report the molecular mechanisms of apoptosis activation and growth inhibition induced by MED in MCF-7 cells. The present results show that MED induces DNA damage through the production of reactive oxygen species (ROS), which resulted in the phosphorylation of H2AX and the activation of the Ataxia telangiectasia mutated kinase (ATM) and p53 signaling pathways. In addition, MED increases the accumulation of IκBα and enhances the association between IKKγ and Hsp27 via the activation of Hsp27, which eventually resulted in the inhibition of TNF-α-induced NF-κB transactivation. Therefore, we conclude that MED inhibits MCF-7 cells by simultaneously activating p53 to induce apoptosis and suppressing NF-κB to disrupt cell proliferation. Because small molecules having both of these effects are rare, further exploration of MED as an antitumor lead compound is needed.
Keywords: Mycoepoxydiene; Polyketide; ROS; p53; NF-κB
Allosteric inhibition of the DNA-dependent ATPase activity of Escherichia coli DNA gyrase by a representative of a novel class of inhibitors by Adam B. Shapiro; Beth Andrews (pp. 900-904).
A novel class of bacterial DNA gyrase inhibitors has been shown previously to form a ternary complex with DNA and gyrase in a site distinct from the fluoroquinolone and ATP binding sites and does not cause double-strand-cleaved complex stabilization like fluoroquinolones. We show that, unlike fluoroquinolones, a representative compound inhibits DNA-dependent ATP hydrolysis by Escherichia coli gyrase and also blocks cleaved complex stabilization by ciprofloxacin. Conversely, ciprofloxacin blocks ATPase inhibition by the novel compound. We conclude that the compound acts allosterically to inhibit ATP binding or hydrolysis and interferes with the gyrase catalytic cycle at a different point than ciprofloxacin.
Keywords: Topoisomerase; Gyrase; ATPase; Inhibitor; Fluoroquinolone; Ciprofloxacin
A novel fibrinogenase from Agkistrodon acutus venom protects against DIC via direct degradation of thrombosis and activation of protein C by Jie-zhen Qi; Xi Lin; Jia-shu Chen; Zhen-hua Huang; Peng-xin Qiu; Guang-mei Yan (pp. 905-913).
The incidence of disseminated intravascular coagulation (DIC), which leads to multiple organ dysfunction and high mortality, has remained constant in recent years. At present, treatments of DIC have focused on preventing cytokine induction, inhibiting coagulation processes and promoting fibrinolysis. Recent clinical trials have supported the use of antithrombin and activated protein C supplementation in DIC. To better understand the mechanism of treatment on DIC, we here report a novel fibrinogenase from Agkistrodon acutus (FIIa) that effectively protected against LPS-induced DIC in a rabbit model, and detected the tissue factors expression in HUVE cells after using FIIa. In vivo, administration of FIIa reduced hepatic and renal damage, increased the concentration of fibrinogen, the activities of protein C, the platelet count, APTT, PT, FDP, the level of AT-III and t-PA, decreased the level of PAI-1, and increased survival rate in LPS-induced DIC rabbits. In vitro experiments, we further confirmed that FIIa up-regulated the expression of t-PA and u-PA, down-regulated the expression of PAI-1, and directly activated protein C. Our findings suggest that FIIa could effectively protect against DIC via direct degradation of microthrombi and activation of protein C as well as provide a novel strategy to develop a single proteinase molecule for targeting the main pathological processes of this disease.
Keywords: Abbreviations; APC; activated protein C; APTT; activated partial thromboplastin time; AT-III; antithrombin III; DIC; disseminated intravascular coagulation; EGF; endothelial growth factor; FDP; fibrin(-ogen) degradation products; FIIa; fibrinogenase II from; Agkistrodon acutus; HUVECs; human umbilical vein endothelial cells; LPS; Lipopolysaccharide; PAI-1; plasminogen activator inhibitor-1; PT; plasma prothrombin time; t-PA; tissue-type plasminogen activators; TNF-α; tumor necrosis factor-α; u-PA; urokinase-like plasminogen activators; VEGF; vascular endothelial growth factorDIC; Fibrinogenase; Lipopolysaccharide; Microthrombi; Protein C
Suppression of NF-κB signaling by andrographolide with a novel mechanism in human platelets: Regulatory roles of the p38 MAPK-hydroxyl radical-ERK2 cascade by Wan J. Lu; Kuan H. Lin; Ming J. Hsu; Duen S. Chou; George Hsiao; Joen R. Sheu (pp. 914-924).
Andrographolide, a novel nuclear factor-κB (NF-κB) inhibitor, is isolated from leaves of Andrographis paniculata. Platelet activation is relevant to a variety of coronary heart diseases. Our recent studies revealed that andrographolide possesses potent antiplatelet activity by activating the endothelial nitric oxide synthase (eNOS)-NO-cyclic GMP pathway. Although platelets are anucleated cells, they also express the transcription factor, NF-κB, that may exert non-genomic functions in platelet activation. Therefore, we further investigated the inhibitory roles of andrographolide in NF-κB-mediated events in platelets. In this study, NF-κB signaling events, including IKKβ phosphorylation, IκBα degradation, and p65 phosphorylation, were time-dependently activated by collagen in human platelets, and these signaling events were attenuated by andrographolide (35 and 75μM). ODQ and KT5823, respective inhibitors of guanylate cyclase and cyclic GMP-dependent kinase (PKG), strongly reversed andrographolide-mediated inhibition of platelet aggregation, relative [Ca2+]i mobilization, and IKKβ, and p65 phosphorylation. In addition, SB203580 (an inhibitor of p38 MAPK), but not PD98059 (an inhibitor of ERKs), markedly abolished IKKβ and p65 phosphorylation. SB203580, NAC (a free-radical scavenger), and BAY11-7082 (an inhibitor of NF-κB) all diminished ERK2 phosphorylation, whereas PD98059, BAY11-7082, and NAC had no effects on p38 MAPK phosphorylation. Furthermore, SB203580, but not BAY11-7082 or PD98059, reduced collagen-induced hydroxyl radical (HO) formation. KT5823 also markedly reversed andrographolide-mediated inhibition of p38 MAPK and ERK2 phosphorylation, and hydroxyl radical formation in platelets. In conclusion, this study demonstrated that andrographolide may involve an increase in cyclic GMP/PKG, followed by inhibition of the p38 MAPK/HO-NF-κB-ERK2 cascade in activated platelets. Therefore, andrographolide may have a high therapeutic potential to treat thromboembolic disorders and may also be considered for treating various inflammatory diseases.
Keywords: Abbreviations; BSA; bovine serum albumin; cPLA; 2; cytosolic phospholipase A; 2; eNOS; endothelial nitric oxide synthase; ESR; electron spin resonance; HO; hydroxyl radical; IKK; IκB kinase; iNOS; inducible nitric oxide synthase; LPS; lipopolysaccharide; NF-κB; nuclear factor-kappa B; PKA; cyclic AMP-dependent kinase; PKG; cyclic GMP-dependent kinase; PP2A; protein phosphatase 2A; PRP; platelet-rich plasma; PGE; 1; prostaglandin E; 1; PPAR; peroxisome proliferator-activated receptor; ROS; reactive oxygen species; TxA; 2; thromboxane A; 2; TNF; tumor necrosis factorAndrographolide; ERK2; Hydroxyl radical; NF-κB; Platelet; p38 MAPK
Ursodeoxycholic acid stimulates the formation of the bile canalicular network by Yuki Ikebuchi; Hidetoshi Shimizu; Kousei Ito; Takashi Yoshikado; Yoshihide Yamanashi; Tappei Takada; Hiroshi Suzuki (pp. 925-935).
Ursodeoxycholic acid (UDCA) is a hepatoprotective bile acid used in the treatment of chronic liver diseases. Although several pharmacological effects, including choleresis and inhibition of apoptosis, have been proposed, the impact of UDCA on hepatic structure is not well understood. Here, the influence of UDCA on bile canalicular (BC) morphology was evaluated in vitro in immortalized rat hepatocytes (McA-RH 7777 cells) and primary rat hepatocytes. Cells cultured for 3 days in the presence of UDCA, the BC lumen was enlarged and the bile canaliculi were surrounded by multiple cells (≥5) with a continuous canal-like structure, reminiscent of the in vivo BC network. The effects were dependent on p38MAPK and conventional PKC in McA-RH cells, and partially dependent on p38MAPK, MAPK/ERK kinase, and conventional PKC in primary rat hepatocytes. These findings were then studied in vivo in a rat model of dimethylnitrosamine-induced hepatic injury, in which the BC network is significantly disrupted. In accordance with the in vitro observations, administration of UDCA (40mg/kg/day) to the injured rats for 18 days improved the BC network compared with the vehicle control. Serum hepatic markers were not altered by UDCA treatment, suggesting that the morphological effects were due to the direct actions of UDCA on network formation. Our data provide new evidence of the pharmacological potential of UDCA in accelerating or regenerating BC network formation in vitro, in hepatic cell culture models, and in vivo in a rat model of hepatic injury, and provide a basis for understanding its hepatoprotective effects.
Keywords: Ursodeoxycholic acid; Bile canalicular; Biliary excretion; Bile acid
The molecular basis for high affinity of a universal ligand for human bombesin receptor (BnR) family members by Hirotsugu Uehara; Simon J. Hocart; Nieves González; Samuel A. Mantey; Tomoo Nakagawa; Tatsuro Katsuno; David H. Coy; Robert T. Jensen (pp. 936-948).
There is increased interest in the Bn-receptor family because they are frequently over/ectopically expressed by tumors and thus useful as targets for imaging or receptor-targeted-cytotoxicity. The synthetic Bn-analog, [d-Tyr6, β-Ala11, Phe13, Nle14]Bn(6–14) [Univ.Lig] has the unique property of having high affinity for all three human BNRs (GRPR, NMBR, BRS-3), and thus could be especially useful for this approach. However, the molecular basis of this property is unclear and is the subject of this study. To accomplish this, site-directed mutagenesis was used after identifying potentially important amino acids using sequence homology analysis of all BnRs with high affinity for Univ.Lig compared to the Cholecystokinin-receptor (CCKAR), which has low affinity. Using various criteria 74 amino acids were identified and 101 mutations made in GRPR by changing each to those of CCKAR or to alanine. 22 GRPR mutations showed a significant decrease in affinity for Univ.Lig (>2-fold) with 2 in EC2[D97N, G112V], 1 in UTM6[Y284A], 2 in EC4[R287N, H300S] showing >10-fold decrease in Univ.Lig affinity. Additional mutations were made to explore the molecular basis for these changes. Our results show that high affinity for Univ.Lig by human Bn-receptors requires positively charged amino acids in extracellular (EC)-domain 4 and to a lesser extent EC2 and EC3 suggesting charge-charge interactions may be particularly important for determining the general high affinity of this ligand. Furthermore, transmembrane amino acids particularly in UTM6 are important contributing both charge-charge interactions as well as interaction with a tyrosine residue in close proximity suggesting possible receptor–peptide cation–π or H-bonding interactions are also important for determining its high affinity.
Keywords: Abbreviations; β-Ala; β-alanine replacement; BB; 1; neuromedin B receptor; BB; 2; gastrin-releasing peptide receptor; BB; 4; bombesin receptor subtype 4 (amphibian); Bn; bombesin; BRS-3; bombesin receptor subtype 3; BnR; member of bombesin receptor family; BSA; bovine serum albumin fraction V; CCK; A; R; cholecystokinin receptor type A; CNS; central nervous system; DMEM; Dulbecco's minimum essential medium; DTT; dithiothreitol; EC; extracellular; FBS; fetal bovine serum; GI; gastrointestinal; GRP; gastrin-releasing peptide; GPCR; G-protein coupled receptor; GRPR; gastrin-releasing peptide receptor; IC; 50; peptide concentration causing half-maximal inhibition of radiolabeled ligand binding, a measure of receptor affinity; Nle; norleucine; NMB; neuromedin B; NMBR; neuromedin B receptor; PBS; phosphate-buffered saline; TM; transmembrane region; Univ.Lig; universal ligand for Bn receptors ([; d; -Tyr; 6; , β-Ala; 11; , Phe; 13; , Nle; 14; ]Bn(6–14)); UTM; upper transmembrane regionsGastrin-releasing peptide; Neuromedin B; Bombesin; BRS-3; Receptor-mutagenesis
Isoniazid as a substrate and inhibitor of myeloperoxidase: Identification of amine adducts and the influence of superoxide dismutase on their formation by Louisa V. Forbes; Paul G. Furtmüller; Irada Khalilova; Rufus Turner; Christian Obinger; Anthony J. Kettle (pp. 949-960).
Anti-tuberculosis prodrug isoniazid is an inhibitor of the antimicrobial enzyme myeloperoxidase (MPO). MPO oxidizes isoniazid to products that could compromise delivery of the prodrug to the mycobacterium ( Mtb).Neutrophils ingest Mycobacteria tuberculosis ( Mtb) in the lungs of infected individuals. During phagocytosis they use myeloperoxidase (MPO) to catalyze production of hypochlorous acid (HOCl), their most potent antimicrobial agent. Isoniazid (INH), the foremost antibiotic in the treatment of tuberculosis, is oxidized by MPO. It rapidly reduced compound I of MPO [ k=(1.22±0.05)×106M−1s−1] but reacted less favorably with compound II [(9.8±0.6)×102M−1s−1]. Oxidation of INH by MPO and hydrogen peroxide was unaffected by chloride, the physiological substrate for compound I, and the enzyme was partially converted to compound III. This indicates that INH is oxidized outside the classical peroxidation cycle. In combination with superoxide dismutase (SOD), MPO oxidized INH without exogenous hydrogen peroxide. SOD must favor reduction of oxygen by the INH radical to give superoxide and ultimately hydrogen peroxide. In both oxidation systems, an adduct with methionine was formed and it was a major product with MPO and SOD. We show that it is a conjugate of an acyldiimide with amines. INH substantially inhibited HOCl production by MPO and neutrophils below pharmacological concentrations. The reversible inhibition is explained by diversion of MPO to its ferrous and compound III forms during oxidation of INH. MPO, along with SOD released by Mtb, will oxidize INH at sites of infection and their interactions are likely to limit the efficacy of the drug, promote adverse drug reactions via formation of protein adducts, and impair a major bacterial killing mechanism of neutrophils.
Keywords: Isoniazid; Myeloperoxidase; Neutrophils; Superoxide dismutase; Oxidation
The protective effect of Alpha lipoic acid on Schwann cells exposed to constant or intermittent high glucose by Lian-Qing Sun; Ying-Ying Chen; Xuan Wang; Xiao-Jin Li; Bing Xue; Ling Qu; Ting-Ting Zhang; Yi-Ming Mu; Ju-Ming Lu (pp. 961-973).
Diabetic peripheral neuropathy (DPN) is one of the most common and costly microvascular complications of diabetes, and no effective therapy exists. Previous studies have demonstrated that oxidative stress may be the unifying factor for the damaging effect of hyperglycemia. The aim of this study was to examine the impact of treatment with Alpha lipoic acid (ALA) on the intermittent high glucose (IHG) or high glucose (HG)-induced oxidative stress-induced mitochondrial pathway activation and Schwann cells (SCs) apoptosis in vitro. Our results suggested that IHG and HG induced SCs apoptosis in both caspase-dependent and caspase-independent pathways related to oxidative stress. More importantly, the cytotoxic effect of IHG was significantly more potent than that of HG. Treatment with ALA inhibited the IHG and HG-induced oxidative stress and apoptosis in SCs. Furthermore, treatment with ALA down-regulated the Bax expression and the release of cytochrome c and AIF translocation, but up-regulated the Bcl-2 expression in SCs. Treatment with ALA attenuated the activation of caspase-3 and caspase-9 and minimized the cleavage of PARP in SCs. These findings suggest that variability in glycemic control could be more deleterious than a constant HG and ALA antagonized the IHG-induced oxidative stress, activation of mitochondrial pathway and apoptosis in SCs.
Keywords: Abbreviations; AIF; apoptosis inducing factor; ALA; Alpha lipoic acid; Apaf-1; apoptotic protease-activating factor-1; cyto c; cytochrome c; DPN; diabetic peripheral neuropathy; 8-OHdG; 8-hydroxy-2-deoxy Guanosine; HG; high glucose; IHG; intermitient high glucose; SDS-PAGE; sodium dodecyl sulfate–polyacrylamide gel electrophoresis; ROS; reactive oxygen species; SCs; Schwann cells; TUNEL; Terminal deoxynucleotidyl transferase-mediated dUTP nick end-labelingHyperglycemia; Peripheral neuropathy; Oxidative stress; Antioxidant
Globular adiponectin inhibits ethanol-induced apoptosis in HepG2 cells through heme oxygenase-1 induction by Saroj Nepal; Mi Jin Kim; Amit Subedi; Eung-Seok Lee; Chul Soon Yong; Jung-Ae Kim; WonKu Kang; Mi-Kyung Kwak; Dharamvir Singh Arya; Pil-Hoon Park (pp. 974-983).
Hepatocellular apoptosis is an essential pathological feature of alcoholic liver disease. Adiponectin, an adipokine predominantly secreted from adipose tissue, has been shown to play beneficial roles in alcoholic liver disease against various inflammatory and pro-apoptotic molecules. However, the effects of adiponectin on ethanol-induced apoptosis in liver cells are largely unknown. Herein, we investigated the role of globular adiponectin (gAcrp) in the prevention of ethanol-induced apoptosis and further tried to decipher the potential mechanisms involved. In the present study, we demonstrated that gAcrp significantly inhibits both ethanol-induced increase in Fas ligand expression and activation of caspase-3 in human hepatoma cell lines (HepG2 cells), suggesting that gAcrp plays a protective role against ethanol-induced apoptosis in liver cells. This protective effect of gAcrp was mediated through adiponectin receptor R1 (adipoR1). Further, globular adiponectin treatment caused induction of heme oxygenase-1 (HO-1) through, at least in part, nuclear factor (erythroid-derived 2)-like 2, (Nrf2) signaling. Treatment with SnPP, a pharmacological inhibitor of HO-1, and knockdown of HO-1 with small interfering RNA (siRNA) restored caspase-3 activity suppressed by gAcrp, indicating a critical role of HO-1 in mediating the protective role of gAcrp in ethanol-induced apoptosis in liver cells. In addition, carbon monoxide, a byproduct obtained from the catabolism of free heme was found to contribute to the anti-apoptotic effect of adiponectin. In conclusion, these data demonstrated that globular adiponectin prevents ethanol-induced apoptosis in HepG2 cells via HO-1 induction and revealed a novel biological response of globular adiponectin in the protection of liver injury from alcohol consumption.
Keywords: Adiponectin; Apoptosis; Ethanol; Heme oxygenase-1; Nrf2