bluuebunny/crossref_metadata_2025_split huggingface dataset:
Riluzole activates TRPC5 channels independently of PLC activity
Authors: Richter Julia M , Schaefer Michael , Hill Kerstin 
Published: October 2013

Background and PurposeThe transient receptor potential channel C5 (TRPC5) is a Ca2+‐permeable cation channel, which is predominantly expressed in the brain. TRPC5 is activated in a PLC‐dependent manner by, as yet, unidentified endogenous messengers. Recently, modulators of TRPC5, like Ca2+, pH and phospholipids, have been identified. However, the role of TRPC5 in vivo is only poorly understood. Novel specific modulators of TRPC5 might help to elucidate its function.Experimental ApproachNovel modulators of TRPC5 were identified in a compound screening of approved drugs and natural compounds. The potency and selectivity of TRPC5‐activating compounds were determined by fluorometric calcium imaging. The biophysical properties of channel activation by these compounds were analysed using electrophysiological measurements.Key ResultsRiluzole was identified as a novel activator of TRPC5 (EC50 9.2 ± 0.5 μM) and its mechanism of action was shown to be independent of G protein signalling and PLC activity. Riluzole‐induced TRPC5 currents were potentiated by La3+ and, utilizing TRPC5 mutants that lack La3+ binding sites, it was confirmed that riluzole and La3+ activate TRPC5 by different mechanisms. Recordings of excised inside‐out patches revealed a relatively direct effect of riluzole on TRPC5.Conclusions and ImplicationsRiluzole can activate TRPC5 heterologously expressed in HEK293 cells as well as those endogenously expressed in the U‐87 glioblastoma cell line. Riluzole does not activate any other member of the TRPC family and could, therefore, despite its action on other ion channels, be a useful pharmacological tool for identifying TRPC5‐specific currents in immortalized cell lines or in acutely isolated primary cells.
Hypoxia modulates the activity of a series of clinically approved tyrosine kinase inhibitors
Authors: Ahmadi M , Ahmadihosseini Z , Allison S J , Begum S , Rockley K , Sadiq M , Chintamaneni S , Lokwani R , Hughes N , Phillips R M 
Published: October 2013

Background and PurposeHypoxia in tumours is known to cause resistance to conventional chemotherapeutic drugs. In contrast, little is known about the effects of hypoxia on targeted anti‐cancer drugs. This study evaluated the effect of hypoxia on a series of clinically approved tyrosine kinase inhibitors (TKIs).Experimental ApproachThe effect of hypoxia (0.1% oxygen) on the activity of conventional cytotoxic drugs (5‐fluorouracil, doxorubicin and vinblastine), the hypoxia‐activated prodrug tirapazamine and 9 TKIs was determined in a panel of cell lines. Where hypoxia had a marked effect on chemosensitivity, Western blot analysis was conducted to determine the effect of hypoxia on target expression and the effect of TKIs on cell signalling response under aerobic and hypoxic conditions.Key ResultsThree patterns of chemosensitivity were observed: resistance under hypoxia, equitoxic activity against hypoxic and aerobic cells, and preferential cytotoxicity to hypoxic cells. Significant hypoxia selectivity (independent of HIF1) was observed in the case of dasatinib and this correlated with the ability of dasatinib to inhibit phosphorylation of Src at tyrosine 530. Sorafenib was significantly less effective under hypoxic conditions but resistance did not correlate with hypoxia‐induced changes in Raf/MEK/ERK signalling.Conclusions and ImplicationsHypoxia influences the activity of TKIs but in contrast to conventional cytotoxic drugs, preferential activity against hypoxic cells can occur. The search for hypoxia‐targeted therapies has been long and fruitless and this study suggests that some clinically approved TKIs could preferentially target the hypoxic fraction of some tumour types.
Andrographolide exerts anti‐hepatitis C virus activity by up‐regulating haeme oxygenase‐1 via the p38 MAPK/Nrf2 pathway in human hepatoma cells
Authors: Lee Jin‐Ching , Tseng Chin‐Kai , Young Kung‐Chia , Sun Hung‐Yu , Wang Shainn‐Wei , Chen Wei‐Chun , Lin Chun‐Kuang , Wu Yu‐Hsuan 
Published: October 2013

Background and PurposeThis study aimed to evaluate the anti‐hepatitis C virus (HCV) activity of andrographolide, a diterpenoid lactone extracted from Andrographis paniculata, and to identify the signalling pathway involved in its antiviral action.Experimental ApproachUsing HCV replicon and HCVcc infectious systems, we identified anti‐HCV activity of andrographolide by measuring protein and RNA levels. A reporter activity assay was used to determine transcriptional regulation of anti‐HCV agents. A specific inhibitor and short hairpin RNAs were used to investigate the mechanism responsible for the effect of andrographolide on HCV replication.Key ResultsIn HCV replicon and HCVcc infectious systems, andrographolide time‐ and dose‐dependently suppressed HCV replication. When combined with IFN‐α, an inhibitor targeting HCV NS3/4A protease (telaprevir), or NS5B polymerase (PSI‐7977), andrographolide exhibited a significant synergistic effect. Andrographolide up‐regulated the expression of haeme oxygenase‐1 (HO‐1), leading to increased amounts of its metabolite biliverdin, which was found to suppress HCV replication by promoting the antiviral IFN responses and inhibiting NS3/4A protease activity. Significantly, these antiviral effects were attenuated by an HO‐1‐specific inhibitor or HO‐1 gene knockdown, indicating that HO‐1 contributed to the anti‐HCV activity of andrographolide. Andrographolide activated p38 MAPK phosphorylation, which stimulated nuclear factor erythroid 2‐related factor 2 (Nrf2)–mediated HO‐1 expression, and this was found to be associated with its anti‐HCV activity.Conclusions and ImplicationsOur results demonstrate that andrographolide has the potential to control HCV replication and suggest that targeting the Nrf2–HO‐1 signalling pathway might be a promising strategy for drug development.
Involvement of midkine in neuroblastoma tumourigenesis
Authors: Kishida S , Kadomatsu K 
Published: October 2013

Midkine is highly expressed in various cancers, including neuroblastoma, one of the most malignant paediatric solid tumours known. Also, it has been shown to be useful as a tumour marker, a prognosis factor and a target of molecular therapy. Several molecular tools (e.g. siRNA, antibodies and RNA aptamer) have been used to establish a midkine‐targeted therapy. The involvement of midkine in tumourigenesis has been demonstrated in vivo in a mouse neuroblastoma model, where targeting it with an RNA aptamer was shown to be an effective treatment for xenografted tumours. Chemoresistance is one of the notable phenotypes regulated by midkine in various cancer cell types. In pancreatic tumours and glioma cells, midkine is expressed in chemoresistant cells and is involved in the survival of these cells in the presence of anticancer drugs. In contrast to these tumours, midkine was found to be expressed in every neuroblastoma cell line tested and the knockdown of midkine alone was sufficient to suppress their growth. These results indicate that neuroblastoma cells are highly dependent on midkine and that a midkine‐targeted therapy could exert a significant effect in these cells. However, to achieve a midkine‐targeted therapy for high‐risk neuroblastoma patients, the further refinement of the RNA aptamer or antibody as tools and the elucidation of midkine signalling are immediate issues that need to be resolved. Regarding the latter, although it has been shown that Notch2 functions as a receptor in neuroblastoma cells, it is likely that other receptors (e.g. anaplastic lymphoma kinase) are also involved in midkine signalling.Linked ArticlesThis article is part of a themed section on Midkine. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2014.171.issue‐4
PDGF and TGF‐β promote tenascin‐C expression in subepithelial myofibroblasts and contribute to intestinal mucosal protection in mice
Authors: Islam M S , Kusakabe M , Horiguchi K , Iino S , Nakamura T , Iwanaga K , Hashimoto H , Matsumoto S , Murata T , Hori M , Ozaki H 
Published: October 2013

Background and PurposeTenascin‐C (TnC) is a multi‐domain extracellular matrix glycoprotein that is expressed at a high level during embryogenesis but is almost absent during normal postnatal life. This multi‐domain complex molecule is reported to associate with both pro‐inflammatory and anti‐inflammatory signalling cascades. In this study, we examined how TnC modulated intestinal inflammation.Experimental ApproachTnC pathophysiology was evaluated in cultures of rat intestinal subepithelial myofibroblasts (ISEMF) and intestinal epithelial cells. Wild‐type and TnC(−/−) mice were treated with dextran sodium sulfate (DSS) to induce colitis.Key ResultsDSS‐induced colitis in mice markedly increased TnC in the damaged mucosal areas and up‐regulated mRNA for TnC, pro‐inflammatory cytokines and growth factors (PDGF‐B and TGF‐β1). In addition, 2,4,6‐trinitrobenzene sulfonic acid‐induced colitis and SAMP1/Yit mice, a model of spontaneous Crohn's disease, also exhibited increased mucosal TnC in colon and ilea respectively. PDGF receptor‐α (PDGFRα) positive ISEMF were the primary TnC‐producing cells in colon tissues. Accordingly, ISEMF collected from the rat colon constitutively expressed both TnC and PDGFRα. PDGF‐BB and TGF‐β1 up‐regulated both TnC mRNA and protein levels in ISEMF. Knock‐down of TnC gene increased susceptibility to DSS‐induced colitis, compared with TnC(+/+) littermates. TnC(−/−) mice showed marked abrasion of intestinal mucosal barrier and increased inflammatory scores. Moreover, TnC accelerated both trans‐well migration and wound healing in epithelial cells.Conclusions and ImplicationsThe pharmacological profiles of PDGF‐BB and TGF‐β in colitis tissues and ISEMF suggest that increased TnC production during inflammation contributed to epithelial cell migration, remodelling and protection of intestinal barriers.
Novel analogues of chlormethiazole are neuroprotective in four cellular models of neurodegeneration by a mechanism with variable dependence on GABAA receptor potentiation
Authors: VandeVrede Lawren , Tavassoli Ehsan , Luo Jia , Qin Zhihui , Yue Lan , Pepperberg David R , Thatcher Gregory R 
Published: October 2013

Background and PurposeChlormethiazole (CMZ), a clinical sedative/anxiolytic agent, did not reach clinical efficacy in stroke trials despite neuroprotection demonstrated in numerous animal models. Using CMZ as a lead compound, neuroprotective methiazole (MZ) analogues were developed, and neuroprotection and GABAA receptor dependence were studied.Experimental ApproachEight MZs were selected from a novel library, of which two were studied in detail. Neuroprotection, glutamate release, intracellular calcium and response to GABA blockade by picrotoxin were measured in rat primary cortical cultures using four cellular models of neurodegeneration. GABA potentiation was assayed in oocytes expressing the α1β2γ2 GABAA receptor.Key ResultsNeuroprotection against a range of insults was retained even with substantial chemical modification. Dependence on GABAA receptor activity was variable: at the extremes, neuroprotection by GN‐28 was universally sensitive to picrotoxin, while GN‐38 was largely insensitive. In parallel, effects on extracellular glutamate and intracellular calcium were associated with GABAA dependence. Consistent with these findings, GN‐28 potentiated α1β2γ2 GABAA function, whereas GN‐38 had a weak inhibitory effect. Neuroprotection against moderate dose oligomeric Aβ1–42 was also tolerant to structural changes.Conclusions and ImplicationsThe results support the concept that CMZ does not contain a single pharmacophore, rather that broad‐spectrum neuroprotection results from a GABAA‐dependent mechanism represented by GN‐28, combined with a mechanism represented in GN‐38 that shows the least dependence on GABAA receptors. These findings allow further refinement of the neuroprotective pharmacophore and investigation into secondary mechanisms that will assist in identifying MZ‐based compounds of use in treating neurodegeneration.
The structural role of receptor tyrosine sulfation in chemokine recognition
Authors: Ludeman Justin P , Stone Martin J 
Published: October 2013

Tyrosine sulfation is a post‐translational modification of secreted and transmembrane proteins, including many GPCRs such as chemokine receptors. Most chemokine receptors contain several potentially sulfated tyrosine residues in their extracellular N‐terminal regions, the initial binding site for chemokine ligands. Sulfation of these receptors increases chemokine binding affinity and potency. Although receptor sulfation is heterogeneous, insights into the molecular basis of sulfotyrosine (sTyr) recognition have been obtained using purified, homogeneous sulfopeptides corresponding to the N‐termini of chemokine receptors. Receptor sTyr residues bind to a shallow cleft defined by the N‐loop and β3‐strand elements of cognate chemokines. Tyrosine sulfation enhances the affinity of receptor peptides for cognate chemokines in a manner dependent on the position of sulfation. Moreover, tyrosine sulfation can alter the selectivity of receptor peptides among several cognate chemokines for the same receptor. Finally, binding to receptor sulfopeptides can modulate the oligomerization state of chemokines, thereby influencing the ability of a chemokine to activate its receptor. These results increase the motivation to investigate the structural basis by which tyrosine sulfation modulates chemokine receptor activity and the biological consequences of this functional modulation.Linked ArticlesThis article is part of a themed section on Molecular Pharmacology of GPCRs. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2014.171.issue‐5
Melatonin MT1 and MT2 receptors display different molecular pharmacologies only in the G‐protein coupled state
Authors: Legros Céline , Devavry Séverine , Caignard Sarah , Tessier Clémence , Delagrange Philippe , Ouvry Christine , Boutin Jean A , Nosjean Olivier 
Published: October 2013

Background and PurposeMelatonin receptors have been extensively characterized regarding their affinity and pharmacology, mostly using 2‐[125I]‐melatonin as a radioligand. Although [3H]‐melatonin has the advantage of corresponding to the endogenous ligand of the receptor, its binding has not been well described.Experimental ApproachWe characterized [3H]‐melatonin binding to the hMT1 and hMT2 receptors expressed in a range of cell lines and obtained new insights into the molecular pharmacology of melatonin receptors.Key ResultsThe binding of [3H]‐melatonin to the hMT1 and hMT2 receptors displayed two sites on the saturation curves. These two binding sites were observed on cell membranes expressing recombinant receptors from various species as well as on whole cells. Furthermore, our GTPγS/NaCl results suggest that these sites on the saturation curves correspond to the G‐protein coupled and uncoupled states of the receptors, whose pharmacology was extensively characterized.Conclusions and ImplicationshMT1 and hMT2 receptors spontaneously exist in two states when expressed in cell lines; these states can be probed by [3H]‐melatonin binding. Overall, our results suggest that physiological regulation of the melatonin receptors may result from complex and subtle mechanisms, a small difference in affinity between the active and inactive states of the receptor, and spontaneous coupling to G‐proteins.
The protein Ocular albinism 1 is the orphan GPCR GPR143 and mediates depressor and bradycardic responses to DOPA in the nucleus tractus solitarii
Authors: Hiroshima Y , Miyamoto H , Nakamura F , Masukawa D , Yamamoto T , Muraoka H , Kamiya M , Yamashita N , Suzuki T , Matsuzaki S , Endo I , Goshima Y 
Published: October 2013

Background and PurposeL‐DOPA is generally considered to alleviate the symptoms of Parkinson's disease by its conversion to dopamine. We have proposed that DOPA is itself a neurotransmitter in the CNS. However, specific receptors for DOPA have not been identified. Recently, the gene product of ocular albinism 1 (OA1) was found to exhibit DOPA‐binding activity. Here, we have investigated whether OA1 is a functional receptor of DOPA in the nucleus tractus solitarii (NTS).Experimental ApproachWe examined immunohistochemical expression of OA1 in the NTS, and the effects of DOPA microinjected into the depressor sites of NTS on blood pressure and heart rate in anaesthetized rats, with or without prior knock‐down of OA1 in the NTS, using shRNA against OA1.Key ResultsUsing a specific OA1 antibody, OA1‐positive cells and nerve fibres were found in the depressor sites of the NTS. OA1 expression in the NTS was markedly suppressed by microinjection into the NTS of adenovirus vectors carrying the relevant shRNA sequences against OA1. In animals treated with OA1 shRNA, depressor and bradycardic responses to DOPA, but not those to glutamate, microinjected into the NTS were blocked. Bilateral injections into the NTS of DOPA cyclohexyl ester, a competitive antagonist against OA1, suppressed phenylephrine‐induced bradycardic responses without affecting blood pressure responses.Conclusion and ImplicationsOA1 acted as a functional receptor for DOPA in the NTS, mediating depressor and bradycardic responses. Our results add to the evidence for a central neurotransmitter role for DOPA, without conversion to dopamine.
Plasma miR‐21 is a novel diagnostic biomarker for biliary tract cancer
Authors: Kishimoto Tomoya , Eguchi Hidetoshi , Nagano Hiroaki , Kobayashi Shogo , Akita Hirofumi , Hama Naoki , Wada Hiroshi , Kawamoto Koichi , Tomokuni Akira , Tomimaru Yoshito , Umeshita Koji , Doki Yuichiro , Mori Masaki 
Published: October 2013

Biliary tract cancer (BTC) has a generally poor prognosis. Furthermore, it is difficult to distinguish BTC from benign biliary disease (BBD) with commonly used modalities. Therefore, a novel biomarker to facilitate cancer detection is highly desirable. Recent studies have reported the use of circulating microRNAs (miRNAs) as biomarkers for cancers. The purpose of this study was to evaluate whether circulating miRNA‐21 (miR‐21) could be used as a biomarker for BTC. Plasma samples were obtained from 94 BTC patients, 50 healthy volunteers (HVs), and 23 BBD patients. miR‐21 levels in the samples were measured by qRT‐PCR. Plasma miR‐21 levels in patients with BTC were significantly higher than in HVs or in patients with BBD (P < 0.0001 for both). Receiver–operator curve (ROC) curve analysis in differentiating BTC patients from HVs indicated that area under the curve (AUC), optimal sensitivity and specificity was 0.93, 85.1% and 100%, respectively, and those in differentiating BTC patients from BBD patients was 0.83, 72.3%, 91.3%, respectively. Validation of these results indicated that the negative predictive value, positive predictive value, sensitivity, specificity, and accuracy in differentiating BTC patients from HVs was 76.6%, 98.6%, 84.0%, 98.0%, and 88.9%, respectively, and those in differentiating BTC patients from BBD patients was 42.2%, 93.0%, 71.2%, 82.6%, and 72.6%, respectively. These sets of values were improved by combining miR‐21 and CA19‐9 measurements. Plasma miR‐21 is a novel diagnostic biomarker for BTC, and may be useful in distinguishing between BTC and BBD patients.
1‐Thia‐4,7‐diaza‐spiro[4.4]nonane‐3,6‐dione: A Structural Motif for 5‐hydroxytryptamine 6 Receptor Antagonism
Authors: Hostetler Greg , Dunn Derek , McKenna Beth A. , Kopec Karla , Chatterjee Sankar 
Published: October 2013

A series of potent 5‐hydroxytryptamine 6 (5‐HT6) receptor antagonists based on 1‐thia‐4,7‐diaza‐spiro[4.4]nonane‐3,6‐dione motif has been disclosed. Enantiomers of potent racemate compound 8a (Ki = 26 nm) displayed difference in activity (Ki of 15 nm versus 855 nm) signaling the influence of the stereochemistry of the chiral center on potency. In addition, the potent enantiomer displayed significant selectivity in biological activities over several related family members.
Synthesis and Evaluation of Novel Oleanolic Acid Derivatives as Potential Antidiabetic Agents
Authors: Zhang Liying , Jia Xiaojian , Dong Jizhe , Chen Dongyin , Liu Jun , Zhang Luyong , Wen Xiaoan 
Published: October 2013

Antidiabetic agents simultaneously inhibiting hepatic glucose production and stimulating hepatic glucose consumption could apply a better control over hyperglycemia. A series of oleanolic acid derivatives with bulky substituents at C‐3 position were designed and synthesized in order to search for this kind of agents. All of the compounds were evaluated biologically in vitro using glycogen phosphorylase and HepG2 cells. The results indicated that several derivatives exhibited moderate‐to‐good inhibitory activities against glycogen phosphorylase. Compound 8g showed the best inhibition with an IC50 value of 5.4 μm. Moreover, most of the derivatives were found to increase the glucose consumption in HepG2 cells in a dose‐dependent manner. The possible binding mode of compound 8g with glycogen phosphorylase was also explored by docking study. 8g was found to have hydrogen bonding interactions with Arg193, Arg310, and Arg60 of the allosteric site.
A comparison of Child Health Programmes recommended for preschool children in selected high‐income countries
Authors: Wood Rachael , Blair Mitch 
Published: October 2013

AbstractBackgroundThe UK Child Health Programme (CHP) aims to ensure that children attain their development and health potential. It comprises a series of proactive child health reviews incorporating growth and development surveillance and health promotion; routine immunizations; and certain screening tests, and is offered to all children. The evidence underpinning different elements of the CHP varies from robust to sparse, and consequently there is uncertainty about optimal programme design. This study aimed to compare the CHP currently recommended in the UK with that recommended in selected other high‐income countries in order to inform ongoing CHP policy development.MethodsThe CHP recommended for preschool children in the UK was compared with that in Australia; Canada; the USA; and Sweden using a combination of literature review, focused website searches, and consultation with experts in the countries studied. Delivery, content, and uptake of child health reviews, immunizations, and screening were considered.ResultsAll the countries studied recommend CHP services including child health reviews, immunizations, and screening to their preschool populations. Despite this superficial uniformity, considerable variation exists between countries in the detail of CHP delivery and content. The UK programme is relatively narrow in scope, offering the fewest child health reviews, a relatively restricted immunization programme (although some expansion is planned), and limited newborn bloodspot screening. Internationally comparable data on the uptake/coverage of CHP services are patchy: the available information suggests substantial variation between and within countries in the uptake of child health reviews.ConclusionsIn the absence of uncontested evidence on the ‘ideal’ CHP for preschool children, demonstrating variation between countries in recommended programmes provides valuable contextual information for policy makers. Further work looking at relationships between CHP services and children's outcomes would add further value.