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1

Overexpression of the Mitochondrial T3 Receptor Induces Skeletal Muscle Atrophy during Aging  

Microsoft Academic Search

In previous studies, we characterized a new hormonal pathway involving a mitochondrial T3 receptor (p43) acting as a mitochondrial transcription factor. In in vitro and in vivo studies, we have shown that p43 increases mitochondrial transcription and mitochondrial biogenesis. In addition, p43 overexpression in skeletal muscle stimulates mitochondrial respiration and induces a shift in metabolic and contractile features of muscle

François Casas; Laurence Pessemesse; Stéphanie Grandemange; Pascal Seyer; Olivier Baris; Naïg Gueguen; Christelle Ramonatxo; Florence Perrin; Gilles Fouret; Laurence Lepourry; Gérard Cabello; Chantal Wrutniak-Cabello; Jose A. L. Calbet

2009-01-01

2

Myocardial ??adrenergic receptor characteristics in T3?induced ascites and in broiler lines differing in ascites susceptibility  

Microsoft Academic Search

The present study was designed to investigate the myocardial ??adrenergic receptor characteristics in T3?induced ascites in two genetic lines of broilers, in order to look for possible involvement of myocardial ??adrenergic receptors in the development of broiler ascites syndrome. Myocardial membrane fractions were prepared from 6 and 8 week old chickens fed a 1.5 parts\\/10 T3 supplemented diet from day

M. Hassanzadeh Ladmakhi; N. Buys; A. Vanderpooten; E. Decuypere

1997-01-01

3

Myocardial beta-adrenergic receptor characteristics in T(3)-induced ascites and in broiler lines differing in ascites susceptibility.  

PubMed

The present study was designed to investigate the myocardial beta-adrenergic receptor characteristics in T3-induced ascites in two genetic lines of broilers, in order to look for possible involvement of myocardial beta-adrenergic receptors in the development of broiler ascites syndrome. Myocardial membrane fractions were prepared from 6 and 8 week old chickens fed a 1.5 parts/10(6) T(3) supplemented diet from day 1 in order to increase ascites incidence. Also, a similar assay was performed on myocardial cells of ascites sensitive and ascites resistant chickens at 5 weeks of age. The binding capacity and binding affinity of the myocardial beta-adrenergic receptor of the two genetic lines of birds did not differ significantly, but the tendency of beta-adrenergic receptor binding capacity and affinity constants in ascites-sensitive birds was slightly higher compared to ascites-resistant birds. In commercial broilers, although dietary T(3) significantly increased ascites mortality and the RV/TV ratio compared to control, it did not affect significantly beta-adrenergic receptor characteristics. PMID:18483908

Ladmakhi, M H; Buys, N; Vanderpooten, A; Decuypere, E

1997-01-01

4

Altered subcellular distribution of estrogen receptor alpha is implicated in estradiol-induced dual regulation of insulin signaling in 3T3-L1 adipocytes.  

PubMed

We investigated the mechanisms by which estrogen alters insulin signaling in 3T3-L1 adipocytes. Treatment with 17beta-estradiol (E2) did not affect insulin-induced tyrosine phosphorylation of insulin receptor. E2 enhanced insulin-induced tyrosine phosphorylation of insulin receptor substrate-1 (IRS-1), IRS-1/p85 association, phosphorylation of Akt, and 2-deoxyglucose uptake at 10(-8) m, but inhibited these effects at 10(-5) m. A concentration of 10(-5) m E2 enhanced insulin-induced phosphorylation of IRS-1 at Ser(307), which was abolished by treatment with a c-Jun NH(2)-terminal kinase inhibitor. In addition, the effect of E2 was abrogated by pretreatment with a specific estrogen receptor antagonist, ICI182,780. Membrane-impermeable E2, E2-BSA, did not affect the insulin-induced phosphorylation of Akt at 10(-8) m, but inhibited it at 10(-5) m. Furthermore, E2 decreased the amount of estrogen receptor alpha at the plasma membrane at 10(-8) m, but increased it at 10(-5) m. In contrast, the subcellular distribution of estrogen receptor beta was not altered by the treatment. These results indicate that E2 affects the metabolic action of insulin in a concentration-specific manner, that high concentrations of E2 inhibit insulin signaling by modulating phosphorylation of IRS-1 at Ser(307) via a c-Jun NH(2)-terminal kinase-dependent pathway, and that the subcellular redistribution of estrogen receptor alpha in response to E2 may explain the dual effect of E2. PMID:16269459

Nagira, Kiyofumi; Sasaoka, Toshiyasu; Wada, Tsutomu; Fukui, Kazuhito; Ikubo, Mariko; Hori, Satoko; Tsuneki, Hiroshi; Saito, Shigeru; Kobayashi, Masashi

2006-02-01

5

Original article Ontogeny of the liver nuclear T3-receptor  

E-print Network

Original article Ontogeny of the liver nuclear T3-receptor during the last days of incubation be the consequence of a down-regulation by T3 itself. chick embryo / T3-receptor I ontogeny Résumé ― Ontogénie

Paris-Sud XI, Université de

6

Aldosterone inhibits insulin-induced glucose uptake by degradation of insulin receptor substrate (IRS) 1 and IRS2 via a reactive oxygen species-mediated pathway in 3T3-L1 adipocytes.  

PubMed

Serum aldosterone level is clinically known to correlate with body weight and insulin resistance. Because the underlying molecular mechanism is largely unknown, we examined the effect of aldosterone on insulin-induced metabolic signaling leading to glucose uptake in 3T3-L1 adipocytes. Aldosterone reduced the amounts of insulin receptor substrate (IRS) 1 and IRS2 in a time- and dose-dependent manner. As a result, insulin-induced phosphorylation of Akt-1 and -2, and subsequent uptake of 2-deoxyglucose were decreased. Degradation of IRSs was effectively prevented by a glucocorticoid receptor antagonist and antioxidant N-acetylcysteine, but not by a mineralocorticoid receptor antagonist. Because aldosterone induced phosphorylation of IRS1 at Ser(307), responsible kinases were investigated, and we revealed that rapamycin and BMS345541, but neither SP600125 nor calphostin C, conferred for degradation of IRSs. Although lactacystin prevented the degradation of IRSs, glucose uptake was not preserved. Importantly, sucrose-gradient-sediment intracellular fraction analysis revealed that lactacystin did not effectively restore the reduction of IRS1 in the low-density microsome fraction, important for the transduction of insulin's metabolic signaling. These results indicate that aldosterone deteriorates metabolic action of insulin by facilitating the degradation of IRS1 and IRS2 via glucocorticoid receptor-mediated production of reactive oxygen species, and activation of IkappaB Kinase beta and target of rapamycin complex 1. Thus, aldosterone appears to be a novel key factor in the development of insulin resistance in visceral obesity. PMID:19095745

Wada, Tsutomu; Ohshima, Satoshi; Fujisawa, Eriko; Koya, Daisuke; Tsuneki, Hiroshi; Sasaoka, Toshiyasu

2009-04-01

7

Depletion of the p43 Mitochondrial T3 Receptor Increases Sertoli Cell Proliferation in Mice  

PubMed Central

Among T3 receptors, TR?1 is ubiquitous and its deletion or a specific expression of a dominant-negative TR?1 isoform in Sertoli cell leads to an increase in testis weight and sperm production. The identification of a 43-kDa truncated form of the nuclear receptor TR?1 (p43) in the mitochondrial matrix led us to test the hypothesis that this mitochondrial transcription factor could regulate Sertoli cell proliferation. Here we report that p43 depletion in mice increases testis weight and sperm reserve. In addition, we found that p43 deletion increases Sertoli cell proliferation in postnatal testis at 3 days of development. Electron microscopy studies evidence an alteration of mitochondrial morphology observed specifically in Sertoli cells of p43?/? mice. Moreover, gene expression studies indicate that the lack of p43 in testis induced an alteration of the mitochondrial-nuclear cross-talk. In particular, the up-regulation of Cdk4 and c-myc pathway in p43?/? probably explain the extended proliferation recorded in Sertoli cells of these mice. Our finding suggests that T3 limits post-natal Sertoli cell proliferation mainly through its mitochondrial T3 receptor p43. PMID:24040148

Fumel, Betty; Roy, Stéphanie; Fouchécourt, Sophie; Livera, Gabriel; Parent, Anne-Simone; Casas, François; Guillou, Florian

2013-01-01

8

Phosphatidylcholine induces apoptosis of 3T3-L1 adipocytes  

PubMed Central

Background Phosphatidylcholine (PPC) formulation is used for lipolytic injection, even though its mechanism of action is not well understood. Methods The viability of 3T3-L1 pre-adipocytes and differentiated 3T3-L1 cells was measured after treatment of PPC alone, its vehicle sodium deoxycholate (SD), and a PPC formulation. Western blot analysis was performed to examine PPC-induced signaling pathways. Results PPC, SD, and PPC formulation significantly decreased 3T3-L1 cell viability in a concentration-dependent manner. PPC alone was not cytotoxic to CCD-25Sk human fibroblasts at concentrations <1 mg/ml, whereas SD and PPC formulation were cytotoxic. Western blot analysis demonstrated that PPC alone led to the phosphorylation of the stress signaling proteins, such as p38 mitogen-activated protein kinase and c-Jun N-terminal kinase, and activated caspase-9, -8, -3 as well as cleavage of poly(ADP-ribose) polymerase. However, SD did not activate the apoptotic pathways. Instead, SD and PPC formulation induced cell membrane lysis, which may lead to necrosis of cells. Conclusions PPC results in apoptosis of 3T3-L1 cells. PMID:22145579

2011-01-01

9

Low-intensity pulsed ultrasound-induced ATP increases bone formation via the P2X7 receptor in osteoblast-like MC3T3-E1 cells.  

PubMed

Low-intensity pulsed ultrasound (LIPUS) is used for bone healing in orthopedics and dentistry. It has been shown that LIPUS induces the secretion of extracellular adenosine triphosphate (ATP), a key mediator of osteoblast response to mechanical stimuli. However, the detailed mechanism of LIPUS-induced osteogenesis has been elusive. In this study, we investigated the role of the P2X7 receptor in LIPUS-induced osteogenesis. LIPUS induced the release of extracellular ATP, differentiation of osteoblasts and osteogenesis via the P2X7 receptor, without affecting the activity of alkaline phosphatase (ALPase). These results suggest that LIPUS-induced extracellular ATP promotes bone formation via the osteoblast P2X7 receptor independently of ALPase. PMID:25542352

Manaka, Soichiro; Tanabe, Natsuko; Kariya, Taro; Naito, Masako; Takayama, Tadahiro; Nagao, Mayu; Liu, Di; Ito, Koichi; Maeno, Masao; Suzuki, Naoto; Miyazaki, Masashi

2015-01-30

10

Thyroid hormone (T3) inhibits ciprofibrate-induced transcription of genes encoding beta-oxidation enzymes: cross talk between peroxisome proliferator and T3 signaling pathways.  

PubMed Central

Peroxisome proliferators cause rapid and coordinated transcriptional activation of genes encoding peroxisomal beta-oxidation system enzymes by activating peroxisome proliferator-activated receptor (PPAR) isoform(s). Since the thyroid hormone (T3; 3,3',5-triiodothyronine) receptor (TR), another member of the nuclear hormone receptor superfamily, regulates a subset of fatty acid metabolism genes shared with PPAR, we examined the possibility of interplay between peroxisome proliferator and T3 signaling pathways. T3 inhibited ciprofibrate-induced luciferase activity as well as the endogenous peroxisomal beta-oxidation enzymes in transgenic mice carrying a 3.2-kb 5'-flanking region of the rat peroxisomal enoyl-CoA hydratase/3-hydroxyacyl-CoA dehydrogenase gene fused to the coding region of luciferase. Transfection assays in hepatoma H4-II-E-C3 and CV-1 cells indicated that this inhibition is mediated by TR in a ligand-dependent fashion. Gel shift assays revealed that modulation of PPAR action by TR occurs through titration of limiting amounts of retinoid X receptor (RXR) required for PPAR activation. Increasing amounts of RXR partially reversed the inhibition in a reciprocal manner; PPAR also inhibited TR activation. Results with heterodimerization-deficient TR and PPAR mutants further confirmed that interaction between PPAR and TR signaling systems is indirect. These results suggest that a convergence of the peroxisome proliferator and T3 signaling pathways occurs through their common interaction with the heterodimeric partner RXR. Images Fig. 1 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 PMID:8524810

Chu, R; Madison, L D; Lin, Y; Kopp, P; Rao, M S; Jameson, J L; Reddy, J K

1995-01-01

11

Interaction of human beta 1 thyroid hormone receptor and its mutants with DNA and retinoid X receptor beta. T3 response element-dependent dominant negative potency.  

PubMed Central

Mutations in the human beta thyroid hormone receptor (h-TR beta) gene are associated with the syndrome of generalized resistance to thyroid hormone. We investigated the interaction of three h-TR beta 1 mutants representing different types of functional impairment (kindreds ED, OK, and PV) with different response elements for 3,3',5-triiodothyronine (T3) and with retinoid X receptor beta (RXR beta). The mutant receptors showed an increased tendency to form homodimers on a palindromic T3-response element (TREpal), a direct repeat (DR + 4), and an inverted palindrome (TRElap). On TRElap, wild type TR binding was decreased by T3, while the mutant receptors showed a variably decreased degree of dissociation from TRElap in response to T3. The extent of dissociation was proportional to their T3 binding affinities. RXR beta induced the formation of h-TR beta 1:RXR beta heterodimers equally well for mutants and the wild type h-TR beta 1 on these T3 response elements. However, the T3-dependent increase in heterodimerization with RXR beta was absent or reduced for the mutant TRs. Transient transfection studies indicated that the dominant negative potency was several-fold more pronounced on the TRElap as compared to TREpal or DR + 4. In CV-1 and HeLa cells, transfection of RXR beta could not reverse the dominant negative action. These results demonstrate that the binding of mutant h-TRs to DNA, as well as their dominant negative potency, are TRE dependent. In addition, competition for DNA binding, rather than for limiting amounts of RXR beta, is likely to mediate the dominant negative action. Images PMID:8408652

Meier, C A; Parkison, C; Chen, A; Ashizawa, K; Meier-Heusler, S C; Muchmore, P; Cheng, S Y; Weintraub, B D

1993-01-01

12

T3-induced liver AMP-activated protein kinase signaling: Redox dependency and upregulation of downstream targets  

PubMed Central

AIM: To investigate the redox dependency and promotion of downstream targets in thyroid hormone (T3)-induced AMP-activated protein kinase (AMPK) signaling as cellular energy sensor to limit metabolic stresses in the liver. METHODS: Fed male Sprague-Dawley rats were given a single ip dose of 0.1 mg T3/kg or T3 vehicle (NaOH 0.1 N; controls) and studied at 8 or 24 h after treatment. Separate groups of animals received 500 mg N-acetylcysteine (NAC)/kg or saline ip 30 min prior T3. Measurements included plasma and liver 8-isoprostane and serum ?-hydroxybutyrate levels (ELISA), hepatic levels of mRNAs (qPCR), proteins (Western blot), and phosphorylated AMPK (ELISA). RESULTS: T3 upregulates AMPK signaling, including the upstream kinases Ca2+-calmodulin-dependent protein kinase kinase-? and transforming growth factor-?-activated kinase-1, with T3-induced reactive oxygen species having a causal role due to its suppression by pretreatment with the antioxidant NAC. Accordingly, AMPK targets acetyl-CoA carboxylase and cyclic AMP response element binding protein are phosphorylated, with the concomitant carnitine palmitoyltransferase-1? (CPT-1?) activation and higher expression of peroxisome proliferator-activated receptor-? co-activator-1? and that of the fatty acid oxidation (FAO)-related enzymes CPT-1?, acyl-CoA oxidase 1, and acyl-CoA thioesterase 2. Under these conditions, T3 induced a significant increase in the serum levels of ?-hydroxybutyrate, a surrogate marker for hepatic FAO. CONCLUSION: T3 administration activates liver AMPK signaling in a redox-dependent manner, leading to FAO enhancement as evidenced by the consequent ketogenic response, which may constitute a key molecular mechanism regulating energy dynamics to support T3 preconditioning against ischemia-reperfusion injury. PMID:25516653

Videla, Luis A; Fernández, Virginia; Cornejo, Pamela; Vargas, Romina; Morales, Paula; Ceballo, Juan; Fischer, Alvaro; Escudero, Nicolás; Escobar, Oscar

2014-01-01

13

The T3R? gene encoding a thyroid hormone receptor is essential for post-natal development and thyroid hormone production  

Microsoft Academic Search

The diverse functions of thyroid hormones are thought to be mediated by two nuclear receptors, T3R?1 and T3R?, encoded by the genes T3R? and T3R? respectively. The T3R? gene also produces a non-ligand-binding protein T3R?2. The in vivo functions of these receptors are still unclear. We describe here the homozygous inactivation of the T3R? gene which abrogates the production of

A. Fraichard; O. Chassande; M. Plateroti; J. P. Roux; J. Trouillas; C. Dehay; C. Legrand; K. Gauthier; M. Kedinger; L. Malaval; B. Rousset; J. Samarut

1997-01-01

14

Structure-activity relations in binding of perfluoroalkyl compounds to human thyroid hormone T3 receptor.  

PubMed

Perfluoroalkyl compounds (PFCs) have been shown to disrupt thyroid functions through thyroid hormone receptor (TR)-mediated pathways, but direct binding of PFCs with TR has not been demonstrated. We investigated the binding interactions of 16 structurally diverse PFCs with human TR, their activities on TR in cells, and the activity of perfluorooctane sulfonate (PFOS) in vivo. In fluorescence competitive binding assays, most of the 16 PFCs were found to bind to TR with relative binding potency in the range of 0.0003-0.05 compared with triiodothyronine (T3). A structure-binding relationship for PFCs was observed, where fluorinated alkyl chain length longer than ten, and an acid end group were optimal for TR binding. In thyroid hormone (TH)-responsive cell proliferation assays, PFOS, perfluorohexadecanoic acid, and perfluorooctadecanoic acid exhibited agonistic activity by promoting cell growth. Furthermore, similar to T3, PFOS exposure promoted expression of three TH upregulated genes and inhibited three TH downregulated genes in amphibians. Molecular docking analysis revealed that most of the tested PFCs efficiently fit into the T3-binding pocket in TR and formed a hydrogen bond with arginine 228 in a manner similar to T3. The combined in vitro, in vivo, and computational data strongly suggest that some PFCs disrupt the normal activity of TR pathways by directly binding to TR. PMID:24819616

Ren, Xiao-Min; Zhang, Yin-Feng; Guo, Liang-Hong; Qin, Zhan-Fen; Lv, Qi-Yan; Zhang, Lian-Ying

2015-02-01

15

Receptors for NPY and PACAP differ in expression and activity during adipogenesis in the murine 3T3-L1 fibroblast cell line  

PubMed Central

Background and purpose: Neuropeptides are involved in the regulation of food intake in the central nervous system, but they might also act on peripheral fat tissue via neuropeptide receptors. Experimental approach: We investigated the receptor expression and activity of pituitary adenylate cyclase-activating polypeptide (PACAP) and of neuropeptide Y at the mRNA and protein levels in the 3T3-L1 fibroblast line during differentiation into adipocytes. Intracellular calcium concentration was measured by calcium imaging. Key results: The PACAP receptors PAC1 and VPAC2 as well as the neuropeptide Y1 receptor were expressed at the mRNA level in fibroblasts, pre-adipocytes and adipocytes. The mRNA profile of the PAC1 receptor isoforms showed the HOP sequence, whereas the HIP-isoform was present in subconfluent 3T3-L1 fibroblasts only. At the protein level, the mature 3T3-L1 adipocytes produced the PAC1 and Y1 receptors; only the PAC1 receptor showed carbohydrate residues. Both neuropeptides induced an increase of intracellular calcium in mature adipocytes, which was absent in the precursor cells. These changes in calcium were mediated by Y1 and PAC1 receptors as demonstrated by the effects of specific receptor agonists and antagonists. Conclusions and implications: As the PAC1-HOP receptor variant seems to be responsible for PACAP-mediated calcium influx in many cell types, the HOP sequence might also mediate the increase in intracellular calcium in adipocytes. Because a high intracellular calcium level is associated with lipogenesis, peptidergic innervation of adipose tissue might be involved in stress-induced obesity. British Journal of Pharmacology (2009) 157, 620–632; doi:10.1111/j.1476-5381.2009.00164.x; published online 27 April 2009 PMID:19422400

Gericke, Martin T; Kosacka, Joanna; Koch, Daniela; Nowicki, Marcin; Schröder, Thomas; Ricken, Albert M; Nieber, Karen; Spanel-Borowski, Katharina

2009-01-01

16

Curcumin induces apoptosis in immortalized NIH 3T3 and malignant cancer cell lines  

Microsoft Academic Search

Curcumin, which is a widely used dietary pigment and spice, has been demonstrated to be an effective inhibitor of tumor promotion in mouse skin carcinogenesis. We report that curcumin induces cell shrinkage, chromatin condensation, and DNA fragmentation, characteristics of apoptosis, in immortalized mouse embryo fibroblast NIH 3T3 erb B2 oncogene?transformed NIH 3T3, mouse sarcoma S180, human colon cancer cell HT?29,

Ming?Chung Jiang

1996-01-01

17

Zinc deficiency induces oxidative stress and AP1 activation in 3T3 cells  

Microsoft Academic Search

It has been postulated that one mechanism underlying zinc deficiency–induced tissue alterations is excessive cellular oxidative damage. In the present study we investigated if zinc deficiency can induce oxidative stress in 3T3 cells and trigger select intracellular responses that have been associated to oxidative stress. Cells were exposed to control media or to chelated media containing 0.5, 5, or 50

Patricia I Oteiza; Michael S Clegg; M. Paola Zago; Carl L Keen

2000-01-01

18

Type-2 cannabinoid receptor regulates proliferation, apoptosis, differentiation, and OPG/RANKL ratio of MC3T3-E1 cells exposed to Titanium particles.  

PubMed

The type-2 cannabinoid receptor (CB2) is expressed in osteoblasts and plays a role in bone metabolism through regulation on bone mass and bone turnover, but the functional importance of CB2 in osteoblasts under Titanium (Ti) stimulation is incompletely understood. This study aimed to investigate the CB2 expression in osteoblasts under Ti stimulation and the effects of CB2 activation on proliferation, apoptosis, differentiation, mineralization, OPG, and RANKL expression of MC3T3-E1 cells exposed to Ti particles. MC3T3-E1 cells were incubated in the presence of Ti particles with or without CB2-specific agonist HU-308 and antagonist SR144528. Ti particles treatment obviously induced the CB2 expression in MC3T3-E1 cells, and reduced the cell survival in a dose- and time-dependent manner (p < 0.05). Addition of HU-308 could dose-dependently alleviate the Ti-induced decrease of cell survival (p < 0.05). The flow cytometry assay showed that comparing with the control group, the apoptosis rate and caspase-3 activity in the Ti group were significantly elevated (p < 0.05), which could be alleviated by HU-308. Moreover, HU-308 effectively attenuated the decrease of cell mineralization capability, alkaline phosphates (ALP) and osteocalcin activity, and increase of OPG/RANKL ratio induced by Ti particles treatment (p < 0.05). These effects were partially counteracted by combined treatment of CB2 antagonist SR144528 (p < 0.05). In conclusion, CB2 activation has a favorable inhibitory effect on Ti-induced reactions in MC3T3-E1 cell through modulating proliferation, apoptosis, differentiation, and RANKL expression. These findings suggest that activation of CB2 might be an effective therapeutic strategy to promote bone formation and reduce bone dissolution. PMID:25292314

Qiu, Shang; Zhao, Fengchao; Tang, Xianye; Pei, Fang; Dong, Hongyan; Zhu, Liang; Guo, Kaijin

2015-01-01

19

Prednisolone induces the Wnt signalling pathway in 3T3-L1 adipocytes  

PubMed Central

Synthetic glucocorticoids are potent anti-inflammatory drugs but show dose-dependent metabolic side effects such as the development of insulin resistance and obesity. The precise mechanisms involved in these glucocorticoid-induced side effects, and especially the participation of adipose tissue in this are not completely understood. We used a combination of transcriptomics, antibody arrays and bioinformatics approaches to characterize prednisolone-induced alterations in gene expression and adipokine secretion, which could underlie metabolic dysfunction in 3T3-L1 adipocytes. Several pathways, including cytokine signalling, Akt signalling, and Wnt signalling were found to be regulated at multiple levels, showing that these processes are targeted by prednisolone. These results suggest that mechanisms by which prednisolone induce insulin resistance include dysregulation of wnt signalling and immune response processes. These pathways may provide interesting targets for the development of improved glucocorticoids. PMID:23506355

Fleuren, Wilco W. M.; Linssen, Margot M. L.; Toonen, Erik J. M.; van der Zon, Gerard C. M.; Guigas, Bruno; de Vlieg, Jacob; Dokter, Wim H. A.; Ouwens, D. Margriet

2013-01-01

20

Mechanisms for proteinase-activated receptor 1-triggered prostaglandin E2 generation in mouse osteoblastic MC3T3-E1 cells.  

PubMed

Abstract We analyzed signaling mechanisms for prostaglandin E2 (PGE2) production following activation of proteinase-activated receptor-1 (PAR1), a thrombin receptor, in preosteoblastic MC3T3-E1 cells. PAR1 stimulation caused PGE2 release, an effect suppressed by inhibitors of COX-1, COX-2, iPLA2, cPLA2, MAP kinases (MAPKs), Src, EGF receptor (EGFR) tyrosine kinase (EGFR-TK) and matrix metalloproteinase (MMP), but not by an intracellular Ca2+ chelator or inhibitors of PI3 kinase, protein kinase C (PKC) and NF-?B. PAR1 activation induced phosphorylation of MAPKs and upregulation of COX-2. The phosphorylation of p38 MAPK was suppressed by inhibitors of Src and EGFR-TK. The COX-2 upregulation was dependent on ERK, p38, EGFR-TK, Src, and COX-2 itself. PAR1 activation also induced MEK-dependent phosphorylation of cAMP response element binding protein (CREB). All inhibitors of EP1, EP2, EP3 and EP4 receptors suppressed the PAR1-triggered PGE2 release. Exogenously applied PGE2 facilitated PAR1-triggered COX-2 upregulation, but it alone had no effect. Together, the PAR1-mediated PGE2 production in MC3T3-E1 cells appears to involve iPLA2 and cPLA2 for arachidonic acid release, and the MEK/ERK/CREB and Src/MMP/EGFR/p38 pathways for COX-2 upregulation, which is facilitated by endogenous PGE2 formed by COX-2. These signaling mechanisms might underlie the role of the thrombin/PAR1/PGE2 system in the early stage of the bone healing. PMID:25205726

Maeda, Yuma; Sekiguchi, Fumiko; Yamanaka, Rumi; Sugimoto, Ryo; Yamasoba, Daichi; Tomita, Shiori; Nishikawa, Hiroyuki; Kawabata, Atsufumi

2015-02-01

21

Characterization of the high-affinity receptors on Swiss 3T3 cells which mediate the binding, internalization and degradation of the mitogenic peptide bombesin.  

PubMed Central

Bombesin and bombesin-related peptides such as gastrin-releasing peptide (GRP) stimulate DNA synthesis and proliferation of Swiss 3T3 cells in culture. We have used 125I-labelled [Tyr4]bombesin and 125I-labelled GRP to characterize and identify the receptors for these peptides on Swiss 3T3 cells. The binding of 125I-[Tyr4]bombesin, which retained full biological activity, was maximal between 20 and 30 min incubation at 37 degrees C, after which continued incubation led to a decline in cell-associated radioactivity. This decline was markedly slowed by the presence of lysosomal enzyme inhibitors. Specificity of the binding site was indicated by the competitive inhibition of binding by bombesin-related peptides, but not by unrelated peptides and growth factors. Scatchard analysis of binding data indicated a single class of high-affinity receptors. The calculated value for the dissociation constant (Kd) was 2.1 nM and each cell possesses approx. 240,000 receptors. Because [Tyr4]bombesin has no free amino group, 125I-GRP was used in chemical cross-linking studies. When disuccinimidyl suberate was used to covalently couple 125I-GRP to the cells, two major radiolabelled complexes were detected with molecular masses of approx. 80,000-85,000 and 140,000. The binding of 125I-[Tyr4]bombesin to the cells was pH-dependent with maximal binding at pH 6.5-7.5 and effectively no specific binding at pH values below 4.5. At 37 degrees C, cell-associated 125I-[Tyr4]bombesin quickly became resistant to removal by acidic buffers, suggesting its rapid transfer to an intracellular compartment. However, pre-incubation with unlabelled [Tyr4]bombesin did not induce down-regulation of bombesin receptors as measured by the subsequent binding of 125I-[Tyr4]bombesin. In contrast with the Swiss 3T3 cells, specific binding of 125I-[Tyr4]bombesin was not detectable in two cell lines which are biologically unresponsive to bombesin-related peptides. Images Fig. 5. Fig. 6. PMID:2844145

Brown, K D; Laurie, M S; Littlewood, C J; Blakeley, D M; Corps, A N

1988-01-01

22

Mouse osteoblastic cell line (MC3T3-E1) expresses extracellular calcium (Ca2+o)-sensing receptor and its agonists stimulate chemotaxis and proliferation of MC3T3-E1 cells  

NASA Technical Reports Server (NTRS)

The calcium-sensing receptor (CaR) is a G protein-coupled receptor that plays key roles in extracellular calcium ion (Ca2+o) homeostasis in parathyroid gland and kidney. Osteoblasts appear at sites of osteoclastic bone resorption during bone remodeling in the "reversal" phase following osteoclastic resorption and preceding bone formation. Bone resorption produces substantial local increases in Ca2+o that could provide a signal for osteoblasts in the vicinity, leading us to determine whether such osteoblasts express the CaR. In this study, we used the mouse osteoblastic, clonal cell line MC3T3-E1. Both immunocytochemistry and Western blot analysis, using an antiserum specific for the CaR, detected CaR protein in MC3T3-E1 cells. We also identified CaR transcripts in MC3T3-E1 cells by Northern analysis using a CaR-specific riboprobe and by reverse transcription-polymerase chain reaction with CaR-specific primers, followed by nucleotide sequencing of the amplified products. Exposure of MC3T3-E1 cells to high Ca2+o (up to 4.8 mM) or the polycationic CaR agonists, neomycin and gadolinium (Gd3+), stimulated both chemotaxis and DNA synthesis in MC3T3-E1 cells. Therefore, taken together, our data strongly suggest that the osteoblastic cell line MC3T3-E1 possesses both CaR protein and mRNA very similar, if not identical, to those in parathyroid and kidney. Furthermore, the CaR in these osteoblasts could play a key role in regulating bone turnover by stimulating the proliferation and migration of such cells to sites of bone resorption as a result of local release of Ca2+o.

Yamaguchi, T.; Chattopadhyay, N.; Kifor, O.; Butters, R. R. Jr; Sugimoto, T.; Brown, E. M.; O'Malley, B. W. (Principal Investigator)

1998-01-01

23

Calcium-sensing receptor-mediated activation of phospholipase C-?1 is downstream of phospholipase C-? and protein kinase C in MC3T3-E1 osteoblasts  

Microsoft Academic Search

Elevated extracellular calcium (Cae) stimulates both chemotaxis and mitogenesis of MC3T3-E1 osteoblasts via a calcium-sensing receptor (CasR). Cae-mediated chemotaxis of these bone-forming cells is dependent on phospholipase C (PLC) and blocked by the Gi-protein inhibitor pertussis toxin. In this study, we examine the signaling mechanisms by which the CasR stimulates PLC activity in MC3T3-E1 osteoblasts. We found that elevated Cae

S. L Godwin; S. P Soltoff

2002-01-01

24

Enhancement of ajoene-induced apoptosis by conjugated linoleic acid in 3T3-L1 adipocytes  

Microsoft Academic Search

Ajoene has been shown to induce apoptosis in 3T3-L1 adipocytes. In this report the effects on apoptosis of combinations of\\u000a ajoene and trans-10, cis-12 conjugated linoleic acid (t10,c12CLA) in 3T3-L1 adipocytes were investigated. Although t10,c12CLA alone had no effect, ajoene\\u000a plus t10,c12CLA reduced cell viability more than ajoene alone at 24 h (59.1 vs. 85.9% of control, respectively; ppp<0.01). Immunoblotting analysis

Jeong-Yeh Yang; Mary Anne Della-Fera; Dorothy B. Hausman; Clifton A. Baile

2007-01-01

25

Functional Proteomic Analysis of Long-term Growth Factor Stimulation and Receptor Tyrosine Kinase Coactivation in Swiss 3T3 Fibroblasts*  

PubMed Central

In Swiss 3T3 fibroblasts, long-term stimulation with PDGF, but not insulin-like growth factor 1 (IGF-1) or EGF, results in the establishment of an elongated migratory phenotype, characterized by the formation of retractile dendritic protrusions and absence of actin stress fibers and focal adhesion complexes. To identify receptor tyrosine kinase-specific reorganization of the Swiss 3T3 proteome during phenotypic differentiation, we compared changes in the pattern of protein synthesis and phosphorylation during long-term exposure to PDGF, IGF-1, EGF, and their combinations using 2DE-based proteomics after 35S- and 33P-metabolic labeling. One hundred and five differentially regulated proteins were identified by mass spectrometry and some of these extensively validated. PDGF stimulation produced the highest overall rate of protein synthesis at any given time and induced the most sustained phospho-signaling. Simultaneous activation with two or three of the growth factors revealed both synergistic and antagonistic effects on protein synthesis and expression levels with PDGF showing dominance over both IGF-1 and EGF in generating distinct proteome compositions. Using signaling pathway inhibitors, PI3K was identified as an early site for signal diversification, with sustained activity of the PI3K/AKT pathway critical for regulating late protein synthesis and phosphorylation of target proteins and required for maintaining the PDGF-dependent motile phenotype. Several proteins were identified with novel PI3K/Akt-dependent synthesis and phosphorylations including eEF2, PRS7, RACK-1, acidic calponin, NAP1L1, Hsp73, and fascin. The data also reveal induction/suppression of key F-actin and actomyosin regulators and chaperonins that enable PDGFR to direct the assembly of a motile cytoskeleton, despite simultaneous antagonistic signaling activities. Together, the study demonstrates that long-term exposure to different growth factors results in receptor tyrosine kinase-specific regulation of relatively small subproteomes, and implies that the strength and longevity of receptor tyrosine kinase-specific signals are critical in defining the composition and functional activity of the resulting proteome. PMID:22956732

Nagano, Kohji; Akpan, Akunna; Warnasuriya, Gayathri; Corless, Steven; Totty, Nick; Yang, Alice; Stein, Robert; Zvelebil, Marketa; Stensballe, Allan; Burlingame, Al; Waterfield, Michael; Cramer, Rainer; Timms, John F.; Naaby-Hansen, Søren

2012-01-01

26

Conjugated linoleic acid suppresses triglyceride accumulation and induces apoptosis in 3T3-L1 preadipocytes  

Microsoft Academic Search

Four sets of experiments were conducted to examine the influence of conjugated linoleic acid (CLA) isomers during proliferation\\u000a and differentiation of cultures of 3T3-L1 preadipocytes using physiological culturing conditions. Cultures treated with either\\u000a albumin [bovine serum albumin (BSA) vehicle] or linoleic acid (LA) served as controls. For the proliferation study (Expt.\\u000a 1), cells were cultured in media containing a crude

M. Evans; C. Geigerman; J. Cook; L. Curtis; B. Kuebler; M. McIntosh

2000-01-01

27

Molecular Mechanisms of Apoptosis Induced by Ajoene in 3T3-L1 Adipocytes  

Microsoft Academic Search

Objective: Determine the biochemical pathways involved in induction of apoptosis by ajoene, an organosulfur compound from garlic.Research Methods and Procedures: Mature 3T3-L1 adipocytes were incubated with ajoene at concentrations up to 200 ?M. Viability and apoptosis were quantified using an MTS-based cell viability assay and an enzyme-linked immunosorbent assay for single-stranded DNA (ssDNA), respectively. Intracellular reactive oxygen species (ROS) production

Jeong-Yeh Yang; Mary Anne Della-Fera; Cass Nelson-Dooley; Clifton A. Baile

2006-01-01

28

Microconstituent-Induced Pitting Corrosion in Aluminum Alloy 2024-T3  

Microsoft Academic Search

Free corrosion immersion experiments were conducted on a commercial airframe material, Al 2024-T3 (UNS A92024), in 0.5 M sodium chloride (NaCl) solution to investigate the role of microconstituents in pitting corrosion. The alloy was found to contain numerous constituent particles (> 300,000 per cm [> 2 million per in.]), and pitting corrosion essentially was attributable to these particles. Two types

G. S. Chen; M. S. Gao; R. P. Wei

1996-01-01

29

Insulin receptor substrate-1 prevents autophagy-dependent cell death caused by oxidative stress in mouse NIH/3T3 cells  

PubMed Central

Background Insulin receptor substrate (IRS)-1 is associated with tumorigenesis; its levels are elevated in several human cancers. IRS-1 protein binds to several oncogene proteins. Oxidative stress and reactive oxygen species (ROS) are involved in the initiation and progression of cancers. Cancer cells produce greater levels of ROS than normal cells do because of increased metabolic stresses. However, excessive production of ROS kills cancer cells. Autophagy usually serves as a survival mechanism in response to stress conditions, but excessive induction of autophagy results in cell death. In addition to inducing necrosis and apoptosis, ROS induces autophagic cell death. ROS inactivates IRS-1 mediated signaling and reduces intracellular IRS-1 concentrations. Thus, there is a complex relationship between IRS-1, ROS, autophagy, and cancer. It is not fully understood how cancer cells grow rapidly and survive in the presence of high ROS levels. Methods and results In this study, we established mouse NIH/3T3 cells that overexpressed IRS-1, so mimicking cancers with increased IRS-1 expression levels; we found that the IRS-1 overexpressing cells grow more rapidly than control cells do. Treatment of cells with glucose oxidase (GO) provided a continuous source of ROS; low dosages of GO promoted cell growth, while high doses induced cell death. Evidence for GO induced autophagy includes increased levels of isoform B-II microtubule-associated protein 1 light chain 3 (LC3), aggregation of green fluorescence protein-tagged LC3, and increased numbers of autophagic vacuoles in cells. Overexpression of IRS-1 resulted in inhibition of basal autophagy, and reduced oxidative stress-induced autophagy and cell death. ROS decreased the mammalian target of rapamycin (mTOR)/p70 ribosomal protein S6 kinase signaling, while overexpression of IRS-1 attenuated this inhibition. Knockdown of autophagy-related gene 5 inhibited basal autophagy and diminished oxidative stress-induced autophagy and cell death. Conclusion Our results suggest that overexpression of IRS-1 promotes cells growth, inhibits basal autophagy, reduces oxidative stress-induced autophagy, and diminishes oxidative stress-mediated autophagy-dependent cell death. ROS-mediated autophagy may occur via inhibition of IRS-1/phosphatidylinositol 3-kinase/mTOR signaling. Our data afford a plausible explanation for IRS-1 involvement in tumor initiation and progression. PMID:22788551

2012-01-01

30

Paprika Pigments Attenuate Obesity-Induced Inflammation in 3T3-L1 Adipocytes  

PubMed Central

Obesity is related to various diseases, such as diabetes, hyperlipidemia, and hypertension. Adipocytokine, which is released from adipocyte cells, affects insulin resistance and blood lipid level disorders. Further, adipocytokine is related to chronic inflammation in obesity condition adipocyte cells. Paprika pigments (PPs) contain large amounts of capsanthin and capsorubin. These carotenoids affect the liver and improve lipid disorders of the blood. However, how these carotenoids affect adipocyte cells remains unknown. Present study examined the effects of PP on adipocytokine secretion, which is related to improvement of metabolic syndrome. In addition, suppressive effects of PP on chronic inflammation in adipocyte cells were analyzed using 3T3-L1 adipocyte cells and macrophage cell coculture experiments. PP promoted 3T3-L1 adipocyte cells differentiation upregulated adiponectin mRNA expression and secretion. Further, coculture of adipocyte and macrophage cells treated with PP showed suppressed interleukin-6 (IL-6), tumor necrosis factor-? (TNF-?), monocyte chemotactic protein-1 (MCP-1), and resistin mRNA expression, similarly to treatment with troglitazone, which is a PPAR? ligand medicine. Conclusion. These results suggest that PP ameliorates chronic inflammation in adipocytes caused by obesity. PP adjusts adipocytokine secretion and might, therefore, affect antimetabolic syndrome diseases. PMID:24049664

Maeda, Hayato; Saito, Shuuichi; Nakamura, Nozomi; Maoka, Takashi

2013-01-01

31

Oxidative changes and apoptosis induced by 1800-MHz electromagnetic radiation in NIH/3T3 cells.  

PubMed

Abstract To investigate the potential adverse effects of mobile phone radiation, we studied reactive oxygen species (ROS), DNA damage and apoptosis in mouse embryonic fibroblasts (NIH/3T3) after intermittent exposure (5?min on/10?min off, for various durations from 0.5 to 8?h) to an 1800-MHz GSM-talk mode electromagnetic radiation (EMR) at an average specific absorption rate of 2?W/kg. A 2',7'-dichlorofluorescin diacetate fluorescence probe was used to detect intracellular ROS levels, immunofluorescence was used to detect ?H2AX foci as a marker for DNA damage, and flow cytometry was used to measure apoptosis. Our results showed a significant increase in intracellular ROS levels after EMR exposure and it reached the highest level at an exposure time of 1?h (p?T3 cells. PMID:24665905

Hou, Qingxia; Wang, Minglian; Wu, Shuicai; Ma, Xuemei; An, Guangzhou; Liu, Huan; Xie, Fei

2014-03-25

32

Dissociation of tumour-promoter-induced effects on prostaglandin release, polyamine synthesis and cell proliferation of 3T3 cells.  

PubMed Central

The phorbol ester 12-O-tetradecanoylphorbol 13-acetate induces tumour promotion, inflammation, cell proliferation and prostaglandin release. Recent reports suggest that the prostaglandins released by 12-O-tetradecanoylphorbol 13-acetate (TPA) initiate a cascade of events leading to polyamine synthesis and cell proliferation. In experiments designed to test this contention, it was found that addition of TPA (1 microM to 1 nM) to confluent mouse 3T3 fibroblasts successively caused the release of prostaglandins E2 and I2, induction of the enzyme ornithine decarboxylase (EC 4.1.1.17), stimulation of [3H]thymidine incorporation into DNA, and cell proliferation. Pretreatment of the cells with the anti-inflammatory steroid dexamethasone (1 microM) or the non-steroidal anti-inflammatory drug indomethacin (1 microM) inhibited TPA-induced prostaglandin release. However, dexamethasone enhanced the other effects of TPA, whereas indomethacin was ineffective. Addition of prostaglandin E2 to the cultures did not induce ornithine decarboxylase activity and cell proliferation. Pretreatment of the cells with 1,3-diaminopropane (1 mM) or alpha-methylornithine (5 mM), inhibitors of polyamine synthesis, decreased TPA-induced ornithine decarboxylase activity without affecting DNA synthesis. TPA stimulated [3H]thymidine incorporation into DNA, even when the ornithine decarboxylase activity was completely blocked. These data suggest that the proliferative effect of TPA on 3T3 cells is independent of prostaglandin release and polyamine synthesis. PMID:7306036

Lanz, R; Brune, K

1981-01-01

33

A possible role of oxidative stress in the vanadium-induced cytotoxicity in the MC3T3E1 osteoblast and UMR106 osteosarcoma cell lines  

Microsoft Academic Search

The cytotoxicity and free radical production induced by vanadium compounds were investigated in an osteoblast (MC3T3E1) and an osteosarcoma (UMR106) cell lines in culture. Vanadate induced cell toxicity, reactive oxygen species (ROS) formation and thiobarbituric acid reactive substances (TBARS) increased in a concentration-dependent manner (0.1–10 mM) after 4 h. The concentration–response curve of vanadate-induced cytotoxicity and oxidative stress in MC3T3E1

Ana Mar??a Cortizo; Liliana Bruzzone; Silvina Molinuevo; Susana Beatriz Etcheverry

2000-01-01

34

Six new chalcones from Angelica keiskei inducing adiponectin production in 3T3-L1 adipocytes.  

PubMed

Angelica keiskei (Ashitaba in Japanese), a traditional herb in Japan, contains abundant prenylated chalcones. It has been reported that the chalcones from A. keiskei showed such bioactivities as anti-bacterial, anti-cancer and anti-diabetic effects. Xanthoangelol, 4-hydroxyderricin and six new chalcones were isolated in this study from an ethanol extract of A. keiskei by octadecyl silyl (ODS) and silica gel chromatography, and identified by 1D- and 2D-nuclear magnetic resonance (NMR) and high-resolution mass spectrometric analyses. The chalcones from A. keiskei markedly increased the expression of the adiponectin gene and the production of adiponectin in 3T3-L1 adipocytes. These results suggest that the chalcones from A. keiskei might be useful for preventing the metabolic syndrome. PMID:22738967

Ohnogi, Hiromu; Kudo, Yoko; Tahara, Kenichi; Sugiyama, Katsumi; Enoki, Tatsuji; Hayami, Shoko; Sagawa, Hiroaki; Tanimura, Yuko; Aoi, Wataru; Naito, Yuji; Kato, Ikunoshin; Yoshikawa, Toshikazu

2012-01-01

35

?-Mangostin Induces Apoptosis and Suppresses Differentiation of 3T3-L1 Cells via Inhibiting Fatty Acid Synthase  

PubMed Central

?-Mangostin, isolated from the hulls of Garcinia mangostana L., was found to have in vitro cytotoxicity against 3T3-L1 cells as well as inhibiting fatty acid synthase (FAS, EC 2.3.1.85). Our studies showed that the cytotoxicity of ?-mangostin with IC50 value of 20 µM was incomplicated in apoptotic events including increase of cell membrane permeability, nuclear chromatin condensation and mitochondrial membrane potential (??m) loss. This cytotoxicity was accompanied by the reduction of FAS activity in cells and could be rescued by 50 µM or 100 µM exogenous palmitic acids, which suggested that the apoptosis of 3T3-L1 preadipocytes induced by ?-mangostin was via inhibition of FAS. Futhermore, ?-mangostin could suppress intracellular lipid accumulation in the differentiating adipocytes and stimulated lipolysis in mature adipocytes, which was also related to its inhibition of FAS. In addition, 3T3-L1 preadipocytes were more susceptible to the cytotoxic effect of ?-mangostin than mature adipocytes. Further studies showed that ?-mangostin inhibited FAS probably by stronger action on the ketoacyl synthase domain and weaker action on the acetyl/malonyl transferase domain. These findings suggested that ?-mangostin might be useful for preventing or treating obesity. PMID:22428036

Quan, Xiaofang; Wang, Yi; Ma, Xiaofeng; Liang, Yan; Tian, Weixi; Ma, Qingyun; Jiang, Hezhong; Zhao, Youxing

2012-01-01

36

Characterization of the respiration of 3T3 cells by laser-induced fluorescence during a cyclic heating process  

NASA Astrophysics Data System (ADS)

The use of lasers in the near infrared spectral range for laser-induced tumor therapy (LITT) demands a new understanding of the thermal responses to repetitive heat stress. The analysis of laser-induced fluorescence during vital monitoring offers an excellent opportunity to solve many of the related issues in this field. The laser-induced fluorescence of the cellular coenzyme NADH was investigated for its time and intensity behavior under heat stress conditions. Heat was applied to vital 3T3 cells (from 22°C to 50°C) according to a typical therapeutical time regime. A sharp increase in temperature resulted in non-linear time behavior when the concentration of this vital coenzyme changed. There are indications that biological systems have a delayed reaction on a cellular level. These results are therefore important for further dosimetric investigations.

Beuthan, J.; Dressler, C.; Zabarylo, U.; Minet, O.

2010-04-01

37

Metformin prevents LYRM1-induced insulin resistance in 3T3-L1 adipocytes via a mitochondrial-dependent mechanism.  

PubMed

We previously proposed that LYR motif containing 1 (LYRM1)-induced mitochondrial reactive oxygen species (ROS) production contributes to obesity-related insulin resistance. Metformin inhibits ROS production and promotes mitochondrial biogenesis in specific tissues. We assessed the effects of metformin on insulin resistance in LYRM1-over-expressing 3T3-L1 adipocytes. Metformin enhanced basal and insulin-stimulated glucose uptake and GLUT4 translocation, reduced IRS-1 and Akt phosphorylation and ROS levels, and affected the expression of regulators of mitochondrial biogenesis in LYRM1-over-expressing adipocytes. Metformin may ameliorate LYRM1-induced insulin resistance and mitochondrial dysfunction in part via a direct antioxidant effect and in part by activating the adenosine monophosphate-activated protein kinase (AMPK)-PGC1/NRFs pathway. PMID:24903160

Qin, Zhen-Ying; Zhang, Min; Dai, Yong-Mei; Wang, Yu-Mei; Zhu, Guan-Zhong; Zhao, Ya-Ping; Ji, Chen-Bo; Qiu, Jie; Cao, Xin-Guo; Guo, Xi-Rong

2014-12-01

38

PPAR? agonist fenofibrate attenuates TNF-?-induced CD40 expression in 3T3-L1 adipocytes via the SIRT1-dependent signaling pathway  

SciTech Connect

The ligand-activated transcription factor peroxisome proliferator-activated receptor-? (PPAR?) participates in the regulation of cellular inflammation. More recent studies indicated that sirtuin1 (SIRT1), a NAD{sup +}-dependent deacetylase, regulates the inflammatory response in adipocytes. However, whether the role of PPAR? in inflammation is mediated by SIRT1 remains unclear. In this study, we aimed to determine the effect of PPAR? agonist fenofibrate on the expressions of SIRT1 and pro-inflammatory cytokine CD40 and underlying mechanisms in 3T3-L1 adipocytes. We found that fenofibrate inhibited CD40 expression and up-regulated SIRT1 expression in tumor necrosis factor-? (TNF-?)-stimulated adipocytes, and these effects of fenofibrate were reversed by PPAR? antagonist GW6471. Moreover, SIRT1 inhibitors sirtinol/nicotinamide (NAM) or knockdown of SIRT1 could attenuate the effect of fenofibrate on TNF-?-induced CD40 expression in adipocytes. Importantly, NF-?B inhibitor pyrrolidine dithiocarbamate (PDTC) augmented the effect of fenofibrate on CD40 expression in adipocytes. Further study found that fenofibrate decreased the expression of acetylated-NF-?B p65 (Ac-NF-?B p65) in TNF-?-stimulated adipocytes, and the effect of fenofibrate was abolished by SIRT1 inhibition. In addition, fenofibrate up-regulated SIRT1 expression through AMPK in TNF-?-stimulated adipocytes. Taken together, these findings indicate that PPAR? agonist fenofibrate inhibits TNF-?-induced CD40 expression in 3T3-L1 adipocytes via the SIRT1-dependent signaling pathway. -- Highlights: • Fenofibrate up-regulates SIRT1 expression in TNF-?-stimulated adipocytes. • Fenofibrate inhibits CD40 expression through SIRT1 in adipocytes. • The effects of fenofibrate on CD40 and SIRT1 expressions are dependent on PPAR?. • Fenofibrate inhibits CD40 expression via SIRT1-dependent deacetylation of NF-?B. • Fenofibrate increases SIRT1 expression through PPAR? and AMPK in adipocytes.

Wang, Weirong [Department of Pharmacology, Cardiovascular Research Center, School of Medicine, Xi'an Jiaotong University, Xi'an, Shaanxi 710061 (China); Lin, Qinqin [Physical Education College, Yanshan University, Qinhuangdao, Hebei 066004 (China); Lin, Rong, E-mail: linrong63@yahoo.com.cn [Department of Pharmacology, Cardiovascular Research Center, School of Medicine, Xi'an Jiaotong University, Xi'an, Shaanxi 710061 (China); Zhang, Jiye [Faculty of Pharmacy, School of Medicine, Xi'an Jiaotong University, Xi'an, Shaanxi 710061 (China); Ren, Feng; Zhang, Jianfeng; Ji, Meixi; Li, Yanxiang [Department of Pharmacology, Cardiovascular Research Center, School of Medicine, Xi'an Jiaotong University, Xi'an, Shaanxi 710061 (China)

2013-06-10

39

Enhancement of ajoene-induced apoptosis by conjugated linoleic acid in 3T3-L1 adipocytes.  

PubMed

Ajoene has been shown to induce apoptosis in 3T3-L1 adipocytes. In this report the effects on apoptosis of combinations of ajoene and trans-10, cis-12 conjugated linoleic acid (t10,c12CLA) in 3T3-L1 adipocytes were investigated. Although t10,c12CLA alone had no effect, ajoene plus t10,c12CLA reduced cell viability more than ajoene alone at 24 h (59.1 vs. 85.9% of control, respectively; p<0.05). Compared to treatment with t10,c12CLA, ajoene increased apoptosis 218% after 24 h (p<0.01), whereas ajoene plus t10,c12CLA increased apoptosis 122% over that caused by ajoene alone (p<0.01). Immunoblotting analysis also indicated that ajoene plus t10,c12CLA caused a greater increase in phosphorylation of c-Jun N-terminal kinase (JNK) and Bax expression and a greater release of mitochondrial proteins (cytochrome c, AIF) than additive responses to each compound alone. Ajoene plus t10,c12CLA also increased ROS production more than that resulting from ajoene treatment alone (264 vs 204% after 40 min, respectively; p<0.01). Furthermore, the antioxidant NAC prevented ROS generation and apoptosis by ajoene plus t10,c12CLA. Interestingly, the combination of ajoene and t10,c12CLA increased NF-kappaB activation and decreased the level of phosphorylated Akt more than each compound alone. Altogether, our observations indicate that t10,c12CLA potentiates the effect of ajoene on apoptosis in 3T3-L1 adipocytes. PMID:17318368

Yang, Jeong-Yeh; Della-Fera, Mary Anne; Hausman, Dorothy B; Baile, Clifton A

2007-06-01

40

Changes in chromatin structure in NIH 3T3 cells induced by valproic acid and trichostatin A.  

PubMed

Valproic acid (VPA) and trichostatin A (TSA) are known histone deacetylase inhibitors (HDACIs) with epigenetic activity that affect chromatin supra-organization, nuclear architecture, and cellular proliferation, particularly in tumor cells. In this study, chromatin remodeling with effects extending to heterochromatic areas was investigated by image analysis in non-transformed NIH 3T3 cells treated for different periods with different doses of VPA and TSA under conditions that indicated no loss of cell viability. Image analysis revealed chromatin decondensation that affected not only euchromatin but also heterochromatin, concomitant with a decreased activity of histone deacetylases and a general increase in histone H3 acetylation. Heterochromatin protein 1-? (HP1-?), identified immunocytochemically, was depleted from the pericentromeric heterochromatin following exposure to both HDACIs. Drastic changes affecting cell proliferation and micronucleation but not alteration in CCND2 expression and in ratios of Bcl-2/Bax expression and cell death occurred following a 48-h exposure of the NIH 3T3 cells particularly in response to higher doses of VPA. Our results demonstrated that even low doses of VPA (0.05?mM) and TSA (10?ng/ml) treatments for 1?h can affect chromatin structure, including that of the heterochromatin areas, in non-transformed cells. HP1-? depletion, probably related to histone demethylation at H3K9me3, in addition to the effect of VPA and TSA on histone H3 acetylation, is induced on NIH 3T3 cells. Despite these facts, alterations in cell proliferation and micronucleation, possibly depending on mitotic spindle defects, require a longer exposure to higher doses of VPA and TSA. PMID:24913611

Felisbino, Marina Barreto; Gatti, Maria Silvia Viccari; Mello, Maria Luiza S

2014-11-01

41

The Effects of Propionate and Valerate on Insulin Responsiveness for Glucose Uptake in 3T3-L1 Adipocytes and C2C12 Myotubes via G Protein-Coupled Receptor 41  

PubMed Central

Since insulin resistance can lead to hyperglycemia, improving glucose uptake into target tissues is critical for regulating blood glucose levels. Among the free fatty acid receptor (FFAR) family of G protein-coupled receptors, GPR41 is known to be the G?i/o-coupled receptor for short-chain fatty acids (SCFAs) such as propionic acid (C3) and valeric acid (C5). This study aimed to investigate the role of GPR41 in modulating basal and insulin-stimulated glucose uptake in insulin-sensitive cells including adipocytes and skeletal muscle cells. Expression of GPR41 mRNA and protein was increased with maximal expression at differentiation day 8 for 3T3-L1 adipocytes and day 6 for C2C12 myotubes. GPR41 protein was also expressed in adipose tissues and skeletal muscle. After analyzing dose-response relationship, 300 µM propionic acid or 500 µM valeric acid for 30 min incubation was used for the measurement of glucose uptake. Both propionic acid and valeric acid increased insulin-stimulated glucose uptake in 3T3-L1 adipocyte, which did not occur in cells transfected with siRNA for GPR41 (siGPR41). In C2C12 myotubes, these SCFAs increased basal glucose uptake, but did not potentiate insulin-stimulated glucose uptake, and siGPR41 treatment reduced valerate-stimulated basal glucose uptake. Therefore, these findings indicate that GPR41 plays a role in insulin responsiveness enhanced by both propionic and valeric acids on glucose uptake in 3T3-L1 adipocytes and C2C12 myotubes, and in valerate-induced increase in basal glucose uptake in C2C12 myotubes. PMID:24748202

Han, Joo-Hui; Kim, In-Su; Jung, Sang-Hyuk; Lee, Sang-Gil; Son, Hwa-Young; Myung, Chang-Seon

2014-01-01

42

Alliin, a Garlic (Allium sativum) Compound, Prevents LPS-Induced Inflammation in 3T3-L1 Adipocytes  

PubMed Central

Garlic (Allium sativum L.) has been used to alleviate a variety of health problems due to its high content of organosulfur compounds and antioxidant activity. The main active component is alliin (S-allyl cysteine sulfoxide), a potent antioxidant with cardioprotective and neuroprotective actions. In addition, it helps to decrease serum levels of glucose, insulin, triglycerides, and uric acid, as well as insulin resistance, and reduces cytokine levels. However its potential anti-inflammatory effect is unknown. We examined the effects of alliin in lipopolysaccharide- (LPS-) stimulated 3T3-L1 adipocytes by RT-PCR, Western blot, and microarrays analysis of 22,000 genes. Incubation of cells for 24?h with 100??mol/L alliin prevented the increase in the expression of proinflammatory genes, IL-6, MCP-1, and Egr-1 in 3T3-L1 adipocytes exposed to 100?ng/mL LPS for 1?h. Interestingly, the phosphorylation of ERK1/2, which is involved in LPS-induced inflammation in adipocytes, was decreased following alliin treatment. Furthermore, the gene expression profile by microarrays evidentiate an upregulation of genes involved in immune response and downregulation of genes related with cancer. The present results have shown that alliin is able to suppress the LPS inflammatory signals by generating an anti-inflammatory gene expression profile and by modifying adipocyte metabolic profile. PMID:24453416

Quintero-Fabián, Saray; Ortuño-Sahagún, Daniel; Vázquez-Carrera, Manuel; López-Roa, Rocío Ivette

2013-01-01

43

Alliin, a garlic (Allium sativum) compound, prevents LPS-induced inflammation in 3T3-L1 adipocytes.  

PubMed

Garlic (Allium sativum L.) has been used to alleviate a variety of health problems due to its high content of organosulfur compounds and antioxidant activity. The main active component is alliin (S-allyl cysteine sulfoxide), a potent antioxidant with cardioprotective and neuroprotective actions. In addition, it helps to decrease serum levels of glucose, insulin, triglycerides, and uric acid, as well as insulin resistance, and reduces cytokine levels. However its potential anti-inflammatory effect is unknown. We examined the effects of alliin in lipopolysaccharide- (LPS-) stimulated 3T3-L1 adipocytes by RT-PCR, Western blot, and microarrays analysis of 22,000 genes. Incubation of cells for 24 h with 100 ?mol/L alliin prevented the increase in the expression of proinflammatory genes, IL-6, MCP-1, and Egr-1 in 3T3-L1 adipocytes exposed to 100 ng/mL LPS for 1 h. Interestingly, the phosphorylation of ERK1/2, which is involved in LPS-induced inflammation in adipocytes, was decreased following alliin treatment. Furthermore, the gene expression profile by microarrays evidentiate an upregulation of genes involved in immune response and downregulation of genes related with cancer. The present results have shown that alliin is able to suppress the LPS inflammatory signals by generating an anti-inflammatory gene expression profile and by modifying adipocyte metabolic profile. PMID:24453416

Quintero-Fabián, Saray; Ortuño-Sahagún, Daniel; Vázquez-Carrera, Manuel; López-Roa, Rocío Ivette

2013-01-01

44

Fluid shear-induced mechanical signaling in MC3T3-E1 osteoblasts requires cytoskeleton-integrin interactions  

NASA Technical Reports Server (NTRS)

Mechanical stimulation of bone induces new bone formation in vivo and increases the metabolic activity and gene expression of osteoblasts in culture. We investigated the role of the actin cytoskeleton and actin-membrane interactions in the transmission of mechanical signals leading to altered gene expression in cultured MC3T3-E1 osteoblasts. Application of fluid shear to osteoblasts caused reorganization of actin filaments into contractile stress fibers and involved recruitment of beta1-integrins and alpha-actinin to focal adhesions. Fluid shear also increased expression of two proteins linked to mechanotransduction in vivo, cyclooxygenase-2 (COX-2) and the early response gene product c-fos. Inhibition of actin stress fiber development by treatment of cells with cytochalasin D, by expression of a dominant negative form of the small GTPase Rho, or by microinjection into cells of a proteolytic fragment of alpha-actinin that inhibits alpha-actinin-mediated anchoring of actin filaments to integrins at the plasma membrane each blocked fluid-shear-induced gene expression in osteoblasts. We conclude that fluid shear-induced mechanical signaling in osteoblasts leads to increased expression of COX-2 and c-Fos through a mechanism that involves reorganization of the actin cytoskeleton. Thus Rho-mediated stress fiber formation and the alpha-actinin-dependent anchorage of stress fibers to integrins in focal adhesions may promote fluid shear-induced metabolic changes in bone cells.

Pavalko, F. M.; Chen, N. X.; Turner, C. H.; Burr, D. B.; Atkinson, S.; Hsieh, Y. F.; Qiu, J.; Duncan, R. L.

1998-01-01

45

Mechanically induced c-fos expression is mediated by cAMP in MC3T3-E1 osteoblasts  

NASA Technical Reports Server (NTRS)

In serum-deprived MC3T3-E1 osteoblasts, mechanical stimulation caused by mild (287 x g) centrifugation induced a 10-fold increase in mRNA levels of the proto-oncogene, c-fos. Induction of c-fos was abolished by the cAMP-dependent protein kinase inhibitor H-89, suggesting that the transient c-fos mRNA increase is mediated by cAMP. Down-regulation of protein kinase C (PKC) activity by chronic TPA treatment failed to significantly reduce c-fos induction, suggesting that TPA-sensitive isoforms of PKC are not responsible for c-fos up-regulation. In addition, 287 x g centrifugation increased intracellular prostaglandin E2 (PGE2) levels 2.8-fold (P<0. 005). Since we have previously shown that prostaglandin E2 (PGE2) can induce c-fos expression via a cAMP-mediated mechanism, we asked whether the increase in c-fos mRNA was due to centrifugation-induced PGE2 release. Pretreatment with the cyclooxygenase inhibitors indomethacin and flurbiprofen did not hinder the early induction of c-fos by mechanical stimulation. We conclude that c-fos expression induced by mild mechanical loading is dependent primarily on cAMP, not PKC, and initial induction of c-fos is not necessarily dependent on the action of newly synthesized PGE2.

Fitzgerald, J.; Hughes-Fulford, M.

1999-01-01

46

Both type I and II IFN induce insulin resistance by inducing different isoforms of SOCS expression in 3T3-L1 adipocytes.  

PubMed

Although elevation of the blood glucose level is a causal adverse effect of treatment with interferon (IFN), the precise underlying molecular mechanism is largely unknown. We examined the effects of type I and type II IFN (IFN-? and IFN-?) on insulin-induced metabolic signaling leading to glucose uptake in 3T3-L1 adipocytes. IFN-? suppressed insulin-induced tyrosine phosphorylation of IRS-1 without affecting its expression, whereas IFN-? reduced both the protein level and tyrosine phosphorylation. Although both IFNs stimulated phosphorylation of STAT1 (at Tyr(701)) and STAT3 (at Tyr(705)) after treatment for 30 min, subsequent properties of induction of the SOCS isoform were different. IFN-? preferentially induced SOCS1 rather than SOCS3, whereas IFN-? strongly induced SOCS3 expression alone. In addition, adenovirus-mediated overexpression of either SOCS1 or SOCS3 inhibited insulin-induced tyrosine phosphorylation of IRS-1, whereas the reduction of IRS-1 protein was observed only in SOCS3-expressed cells. Notably, IFN-?-induced SOCS1 expression and suppression of insulin-induced tyrosine phosphorylation of IRS-1 were attenuated by siRNA-mediated knockdown of STAT1. In contrast, adenovirus-mediated expression of a dominant-negative STAT3 (F-STAT3) attenuated IFN-?-induced SOCS3 expression, reduction of IRS-1 protein, and suppression of insulin-induced glucose uptake but did not have any effect on the IFN-?-mediated SOCS1 expression and inhibition of insulin-induced glucose uptake. Interestingly, pretreatment of IFN-? with IL-6 synergistically suppressed insulin signaling, even when IL-6 alone had no significant effect. These results indicate that type I and type II IFN induce insulin resistance by inducing distinct SOCS isoforms, and IL-6 synergistically augments IFN-?-induced insulin resistance by potentiating STAT3-mediated SOCS3 induction in 3T3-L1 adipocytes. PMID:21386060

Wada, Tsutomu; Hoshino, Masashi; Kimura, Yukari; Ojima, Minoru; Nakano, Tetsuro; Koya, Daisuke; Tsuneki, Hiroshi; Sasaoka, Toshiyasu

2011-06-01

47

Effect of turmeric and its active principle curcumin on t(3)-induced oxidative stress and hyperplasia in rat kidney: a comparison.  

PubMed

The present study was designed to compare the potential of turmeric and its active principle curcumin on T(3)-induced oxidative stress and hyperplasia. Adult male Wistar strain rats were rendered hyperthyroid by T(3) treatment (10 ?g · 100 g(-1) · day(-1) intraperitoneal for 15 days in 0.1 mM NaOH) to induce renal hyperplasia. Another two groups were treated similarly with T(3) along with either turmeric or curcumin (30 mg kg(-1) body weight day(-1) orally for 15 days). The results indicate that T(3) induces both hypertrophy and hyperplasia in rat kidney as evidenced by increase in cell number per unit area, increased protein content, tubular dilation and interstitial edema. These changes were accompanied by increased mitochondrial lipid peroxidation and superoxide dismutase activity without any change in catalase activity and glutathione content suggesting an oxidative predominance. Both turmeric and curcumin were able to restore the level of mitochondrial lipid peroxidation and superoxide dismutase activity in the present dose schedule. T(3)-induced histo-pathological changes were restored with turmeric treatment whereas curcumin administration caused hypoplasia. This may be due to lower concentration of curcumin in the whole turmeric. Thus it is hypothesized that regulation of cell cycle in rat kidney by T(3) is via reactive oxygen species and curcumin reveres the changes by scavenging them. Although the response trends are comparable for both turmeric and curcumin, the magnitude of alteration is more in the later. Turmeric in the current dose schedule is a safer bet than curcumin in normalizing the T(3)-induced hyperplasia may be due to the lower concentration of the active principle in the whole spice. PMID:21966112

Samanta, Luna; Panigrahi, Jogamaya; Bhanja, Shravani; Chainy, Gagan B N

2010-10-01

48

Effect of Turmeric and its Active Principle Curcumin on T3-Induced Oxidative Stress and Hyperplasia in Rat Kidney: A Comparison  

PubMed Central

The present study was designed to compare the potential of turmeric and its active principle curcumin on T3-induced oxidative stress and hyperplasia. Adult male Wistar strain rats were rendered hyperthyroid by T3 treatment (10 ?g · 100 g?1 · day?1 intraperitoneal for 15 days in 0.1 mM NaOH) to induce renal hyperplasia. Another two groups were treated similarly with T3 along with either turmeric or curcumin (30 mg kg?1 body weight day?1 orally for 15 days). The results indicate that T3 induces both hypertrophy and hyperplasia in rat kidney as evidenced by increase in cell number per unit area, increased protein content, tubular dilation and interstitial edema. These changes were accompanied by increased mitochondrial lipid peroxidation and superoxide dismutase activity without any change in catalase activity and glutathione content suggesting an oxidative predominance. Both turmeric and curcumin were able to restore the level of mitochondrial lipid peroxidation and superoxide dismutase activity in the present dose schedule. T3-induced histo-pathological changes were restored with turmeric treatment whereas curcumin administration caused hypoplasia. This may be due to lower concentration of curcumin in the whole turmeric. Thus it is hypothesized that regulation of cell cycle in rat kidney by T3 is via reactive oxygen species and curcumin reveres the changes by scavenging them. Although the response trends are comparable for both turmeric and curcumin, the magnitude of alteration is more in the later. Turmeric in the current dose schedule is a safer bet than curcumin in normalizing the T3-induced hyperplasia may be due to the lower concentration of the active principle in the whole spice. PMID:21966112

Panigrahi, Jogamaya; Bhanja, Shravani; Chainy, Gagan B. N.

2010-01-01

49

Insulin Induces an Increase in Cytosolic Glucose Levels in 3T3-L1 Cells with Inhibited Glycogen Synthase Activation  

PubMed Central

Glucose is an important source of energy for mammalian cells and enters the cytosol via glucose transporters. It has been thought for a long time that glucose entering the cytosol is swiftly phosphorylated in most cell types; hence the levels of free glucose are very low, beyond the detection level. However, the introduction of new fluorescence resonance energy transfer-based glucose nanosensors has made it possible to measure intracellular glucose more accurately. Here, we used the fluorescent indicator protein (FLIPglu-600µ) to monitor cytosolic glucose dynamics in mouse 3T3-L1 cells in which glucose utilization for glycogen synthesis was inhibited. The results show that cells exhibit a low resting cytosolic glucose concentration. However, in cells with inhibited glycogen synthase activation, insulin induced a robust increase in cytosolic free glucose. The insulin-induced increase in cytosolic glucose in these cells is due to an imbalance between the glucose transported into the cytosol and the use of glucose in the cytosol. In untreated cells with sensitive glycogen synthase activation, insulin stimulation did not result in a change in the cytosolic glucose level. This is the first report of dynamic measurements of cytosolic glucose levels in cells devoid of the glycogen synthesis pathway. PMID:25279585

Chowdhury, Helena H.; Kreft, Marko; Jensen, Jørgen; Zorec, Robert

2014-01-01

50

Insulin induces an increase in cytosolic glucose levels in 3T3-L1 cells with inhibited glycogen synthase activation.  

PubMed

Glucose is an important source of energy for mammalian cells and enters the cytosol via glucose transporters. It has been thought for a long time that glucose entering the cytosol is swiftly phosphorylated in most cell types; hence the levels of free glucose are very low, beyond the detection level. However, the introduction of new fluorescence resonance energy transfer-based glucose nanosensors has made it possible to measure intracellular glucose more accurately. Here, we used the fluorescent indicator protein (FLIPglu-600µ) to monitor cytosolic glucose dynamics in mouse 3T3-L1 cells in which glucose utilization for glycogen synthesis was inhibited. The results show that cells exhibit a low resting cytosolic glucose concentration. However, in cells with inhibited glycogen synthase activation, insulin induced a robust increase in cytosolic free glucose. The insulin-induced increase in cytosolic glucose in these cells is due to an imbalance between the glucose transported into the cytosol and the use of glucose in the cytosol. In untreated cells with sensitive glycogen synthase activation, insulin stimulation did not result in a change in the cytosolic glucose level. This is the first report of dynamic measurements of cytosolic glucose levels in cells devoid of the glycogen synthesis pathway. PMID:25279585

Chowdhury, Helena H; Kreft, Marko; Jensen, Jørgen; Zorec, Robert

2014-01-01

51

Fisetin up-regulates the expression of adiponectin in 3T3-L1 adipocytes via the activation of silent mating type information regulation 2 homologue 1 (SIRT1)-deacetylase and peroxisome proliferator-activated receptors (PPARs).  

PubMed

Adiponectin, an adipokine, has been described as showing physiological benefits against obesity-related malfunctions and vascular dysfunction. Several natural compounds that promote the expression and secretion of adipokines in adipocytes could be useful for treating metabolic disorders. This study investigated the effect of fisetin, a dietary flavonoid, on the regulation of adiponectin in adipocytes using 3T3-L1 preadipocytes. The expression and secretion of adiponectin increased in 3T3-L1 cells upon treatment with fisetin in a dose-dependent manner. Fisetin-induced adiponectin secretion was inhibited by peroxisome proliferator-activated receptor (PPAR) antagonists. It was also revealed that fisetin increased the activities of PPARs and silent mating type information regulation 2 homologue 1 (SIRT1) in a dose-dependent manner. Furthermore, the up-regulation of adiponectin and the activation of PPARs induced by fisetin were prevented by a SIRT1 inhibitor. Fisetin also promoted deacetylation of PPAR ? coactivator 1 (PGC-1) and its interaction with PPARs. SIRT knockdown by siRNA significantly decreased both adiponectin production and PPARs-PGC-1 interaction. These results provide evidence that fisetin promotes the gene expression of adiponectin through the activation of SIRT1 and PPARs in adipocytes. PMID:25286082

Jin, Taewon; Kim, Oh Yoen; Shin, Min-Jeong; Choi, Eun Young; Lee, Sung Sook; Han, Ye Sun; Chung, Ji Hyung

2014-10-29

52

Chlamydia Induces Anchorage Independence in 3T3 Cells and Detrimental Cytological Defects in an Infection Model  

PubMed Central

Chlamydia are Gram negative, obligate intracellular bacterial organisms with different species causing a multitude of infections in both humans and animals. Chlamydia trachomatis is the causative agent of the sexually transmitted infection (STI) Chlamydia, the most commonly acquired bacterial STI in the United States. Chlamydial infections have also been epidemiologically linked to cervical cancer in women co-infected with the human papillomavirus (HPV). We have previously shown chlamydial infection results in centrosome amplification and multipolar spindle formation leading to chromosomal instability. Many studies indicate that centrosome abnormalities, spindle defects, and chromosome segregation errors can lead to cell transformation. We hypothesize that the presence of these defects within infected dividing cells identifies a possible mechanism for Chlamydia as a cofactor in cervical cancer formation. Here we demonstrate that infection with Chlamydia trachomatis is able to transform 3T3 cells in soft agar resulting in anchorage independence and increased colony formation. Additionally, we show for the first time Chlamydia infects actively replicating cells in vivo. Infection of mice with Chlamydia results in significantly increased cell proliferation within the cervix, and in evidence of cervical dysplasia. Confocal examination of these infected tissues also revealed elements of chlamydial induced chromosome instability. These results contribute to a growing body of data implicating a role for Chlamydia in cervical cancer development and suggest a possible molecular mechanism for this effect. PMID:23308295

Knowlton, Andrea E.; Fowler, Larry J.; Patel, Rahul K.; Wallet, Shannon M.; Grieshaber, Scott S.

2013-01-01

53

Chlamydia induces anchorage independence in 3T3 cells and detrimental cytological defects in an infection model.  

PubMed

Chlamydia are gram negative, obligate intracellular bacterial organisms with different species causing a multitude of infections in both humans and animals. Chlamydia trachomatis is the causative agent of the sexually transmitted infection (STI) Chlamydia, the most commonly acquired bacterial STI in the United States. Chlamydial infections have also been epidemiologically linked to cervical cancer in women co-infected with the human papillomavirus (HPV). We have previously shown chlamydial infection results in centrosome amplification and multipolar spindle formation leading to chromosomal instability. Many studies indicate that centrosome abnormalities, spindle defects, and chromosome segregation errors can lead to cell transformation. We hypothesize that the presence of these defects within infected dividing cells identifies a possible mechanism for Chlamydia as a cofactor in cervical cancer formation. Here we demonstrate that infection with Chlamydia trachomatis is able to transform 3T3 cells in soft agar resulting in anchorage independence and increased colony formation. Additionally, we show for the first time Chlamydia infects actively replicating cells in vivo. Infection of mice with Chlamydia results in significantly increased cell proliferation within the cervix, and in evidence of cervical dysplasia. Confocal examination of these infected tissues also revealed elements of chlamydial induced chromosome instability. These results contribute to a growing body of data implicating a role for Chlamydia in cervical cancer development and suggest a possible molecular mechanism for this effect. PMID:23308295

Knowlton, Andrea E; Fowler, Larry J; Patel, Rahul K; Wallet, Shannon M; Grieshaber, Scott S

2013-01-01

54

The neck of caveolae is a distinct plasma membrane subdomain that concentrates insulin receptors in 3T3-L1 adipocytes.  

PubMed

Insulin receptors (IRs) segregate on plasma membrane microvilli, but in cells devoid of microvilli, such as adipocytes, the localization of IRs is a matter of controversy. In the present study, we examined the distribution of IRs in the plasma membrane of 3T3-L1 adipocytes. Quantitative electron microscopy indicates that IRs are predominantly associated with the neck, but not the bulb, of caveolae. Caveola necks represent distinct microdomains of the plasma membrane. Indeed, as shown by freeze-fracture analysis, intramembrane particles are concentrated as necklaces around the craters of caveolae. In addition, subcellular fractionation suggests that the neck and the bulb of caveolae present a different resistance to detergent solubility. Finally, cytoskeletal components, including actin, are highly enriched in the membrane area underlying the neck part of caveolae. IRs coimmunoprecipitate with cytoskeletal components, and disruption of the actin cytoskeleton alters IRs expression, localization, and signaling, thus supporting the notion that caveola necks are involved in intracellular signaling by IRs. Together, these results suggest that cytoskeletal proteins anchor IRs to microdomains in the caveola necks of 3T3-L1 adipocytes. By homology with IR localization in other cell types, we suggest that the necks of caveolae may represent the counterpart of microvillar domains in cells poor in microvilli such as adipocytes and that they play an important role as signaling platforms. PMID:17227843

Foti, Michelangelo; Porcheron, Geneviève; Fournier, Margot; Maeder, Christine; Carpentier, Jean-Louis

2007-01-23

55

Proteomics of Oxidative Stress Using Inducible CYP2E1 Expressing HepG2 Cells and 3T3-L1 Adipocytes as Model Systems  

E-print Network

The overall goal of this research was to investigate oxidative stress related changes to the proteomes of 3T3-L1 adipocytes and an inducible CYP2E1 expressing HepG2 cells. Enhanced oxidative stress in hypertrophic adipocytes is associated...

Newton, Billy Walker

2012-07-16

56

Differential expression of mutant and normal beta T3 receptor alleles in kindreds with generalized resistance to thyroid hormone.  

PubMed Central

Thyroid hormone resistance (THR) is primarily an autosomal dominant inherited disease characterized by resistance of pituitary and peripheral tissues to the action of thyroid hormone. We investigated whether the heterogeneous phenotypic features that occur not only among kindreds but also within the same kindred might be due to the expression of differing ratios of mutant and normal receptors in tissues. Using an allele-specific primer extension method, we determined the relative expression of normal and mutant mRNAs from the fibroblasts of affected and unaffected members of two kindreds with TRH: A-H and N-N. While two affected members of A-H, as expected, had nearly equal amounts of normal and mutant hTR beta mRNA, two other members had mutant mRNA levels that accounted for at least 70% of the hTR beta mRNA. Phenotypic variability within and between kindreds with generalized resistance to thyroid hormone GRTH may be due to this differential expression of the mutant and wild type mRNA. Furthermore, when several clinical parameters of THR were compared in several affected members from two kindreds with GRTH, we found that two cases in one kindred exhibited a high mutant-to-normal hTR beta ratio and had considerably more bone resistance during their development. In certain kindreds with THR, differing ratios of normal and mutant hTR receptors may be age and growth related and may account for the reported attenuation of phenotypic symptoms with age. Images PMID:8486789

Mixson, A J; Hauser, P; Tennyson, G; Renault, J C; Bodenner, D L; Weintraub, B D

1993-01-01

57

Basic fibroblast growth factor binds its receptors, is internalized, and stimulates DNA synthesis in Balb/c3T3 cells in the absence of heparan sulfate.  

PubMed

We have investigated the interaction of basic fibroblast growth factor (bFGF) with its receptors and heparan sulfate proteoglycans (HSPG). It has been suggested that in the absence of HSPG, cells are not able to bind bFGF or respond to treatment with bFGF. In our studies, Balb/c3T3 fibroblasts were treated with 50 mM sodium chlorate to completely inhibit (99%) sulfation of proteoglycans. We found that bFGF was able to bind, be internalized, and stimulate DNA synthesis in the absence of HSPG in a dose-dependent manner. bFGF bound to its receptors on chlorate-treated cells with a lower apparent affinity and no change in receptor number. To determine if this decreased affinity bFGF-receptor interaction is functional, we quantitatively analyzed bFGF internalization and stimulation of DNA synthesis in control and chlorate-treated cells. Endocytotic rate constants (ke) for chlorate-treated and control cells were ke = 0. 078 +/- 0.022 min-1 and ke = 0.043 +/- 0.012 min-1, respectively, suggesting that the process of bFGF internalization is not dramatically altered by HSPG. bFGF stimulated DNA synthesis to the same maximal level under both conditions, but chlorate-treated cells were significantly less responsive at low bFGF doses (approximately 10-fold increase in ED50). The differences observed for control and chlorate-treated cells in the dose-response curves for stimulation of DNA synthesis and receptor binding correlated directly, suggesting that receptors are equally capable of eliciting a mitogenic signal under both conditions. It is unlikely that these results are due to residual HSPG since heparinase (I and III) digestion of chlorate-treated cells had little effect. Although the presence of HSPG on the cell surface increases the affinity of bFGF for its receptors, our observations suggest that HSPG are not "absolutely" required for binding, internalization, or stimulation of mitogenic activity. PMID:8663512

Fannon, M; Nugent, M A

1996-07-26

58

ER stress-inducible ATF3 suppresses BMP2-induced ALP expression and activation in MC3T3-E1 cells.  

PubMed

Endoplasmic reticulum (ER) stress suppresses osteoblast differentiation. Activating transcription factor (ATF) 3, a member of the ATF/cAMP response element-binding protein family of transcription factors, is induced by various stimuli including cytokines, hormones, DNA damage, and ER stress. However, the role of ATF3 in osteoblast differentiation has not been elucidated. Treatment with tunicamycin (TM), an ER stress inducer, increased ATF3 expression in the preosteoblast cell line, MC3T3-E1. Overexpression of ATF3 inhibited bone morphogenetic protein 2-stimulated expression and activation of alkaline phosphatase (ALP), an osteogenic marker. In addition, suppression of ALP expression by TM treatment was rescued by silencing of ATF3 using shRNA. Taken together, these data indicate that ATF3 is a novel negative regulator of osteoblast differentiation by specifically suppressing ALP gene expression in preosteoblasts. PMID:24315873

Park, Jae-kyung; Jang, Hoon; Hwang, SeongSoo; Kim, Eun-Jung; Kim, Dong-Ern; Oh, Keon-Bong; Kwon, Dae-Jin; Koh, Jeong-Tae; Kimura, Kumi; Inoue, Hiroshi; Jang, Won-Gu; Lee, Jeong-Woong

2014-01-01

59

Ox-LDL Induces ER Stress and Promotes the adipokines Secretion in 3T3-L1 Adipocytes  

PubMed Central

Adipocytes behave as a rich source of adipokines, which may be the link between obesity and its complications. Endoplasmic reticulum (ER) stress in adipocytes can modulate adipokines secretion. The aim of this study is to evaluate the effect of oxidized low density lipoprotein?ox-LDL?treatment on ER stress and adipokines secretion in differentiated adipocytes. 3T3-L1 pre-adipocytes were cultured and differentiated into mature adipocytes in vitro. Differentiated adipocytes were incubated with various concentrations of ox-LDL (0-100 µg/ml) for 48 hours; 50µg/ml ox-LDL for various times (0-48 hours) with or without tauroursodeoxycholic acid (TUDCA) (0-400µM) pre-treatment. The protein expressions of ER stress markers, glucose regulated protein 78(GRP78) and CCAAT/enhancer binding protein [C/EBP] homologous protein (CHOP) in adipocytes were detected by Western blot. The mRNA expressions of visfatin and resistin were measured by real-time PCR and the protein release of visfatin and resistin in supernatant were determined by ELISA. Treatment with ox-LDL could increase the cholesterol concentration in adipocytes. Ox-LDL induced the expressions of GRP78 and CHOP protein in adipocytes and promoted visfatin and resistin secretion in culture medium in dose and time-dependent manner. TUDCA could attenuate the effect of ox-LDL on GRP78 and CHOP expressions and reduce visfatin and resistin at mRNA and protein level in dose-dependent manner. In conclusion, ox-LDL promoted the expression and secretion of visfatin and resistin through its activation of ER stress, which may be related to the increase of cholesterol load in adipocytes. PMID:24278099

Chen, Yaqin; Chen, Mingjie; Wu, Zhihong; Zhao, Shuiping

2013-01-01

60

Ox-LDL induces ER stress and promotes the adipokines secretion in 3T3-L1 adipocytes.  

PubMed

Adipocytes behave as a rich source of adipokines, which may be the link between obesity and its complications. Endoplasmic reticulum (ER) stress in adipocytes can modulate adipokines secretion. The aim of this study is to evaluate the effect of oxidized low density lipoprotein (ox-LDL) treatment on ER stress and adipokines secretion in differentiated adipocytes. 3T3-L1 pre-adipocytes were cultured and differentiated into mature adipocytes in vitro. Differentiated adipocytes were incubated with various concentrations of ox-LDL (0-100 µg/ml) for 48 hours; 50 µg/ml ox-LDL for various times (0-48 hours) with or without tauroursodeoxycholic acid (TUDCA) (0-400 µM) pre-treatment. The protein expressions of ER stress markers, glucose regulated protein 78(GRP78) and CCAAT/enhancer binding protein [C/EBP] homologous protein (CHOP) in adipocytes were detected by Western blot. The mRNA expressions of visfatin and resistin were measured by real-time PCR and the protein release of visfatin and resistin in supernatant were determined by ELISA. Treatment with ox-LDL could increase the cholesterol concentration in adipocytes. Ox-LDL induced the expressions of GRP78 and CHOP protein in adipocytes and promoted visfatin and resistin secretion in culture medium in dose and time-dependent manner. TUDCA could attenuate the effect of ox-LDL on GRP78 and CHOP expressions and reduce visfatin and resistin at mRNA and protein level in dose-dependent manner. In conclusion, ox-LDL promoted the expression and secretion of visfatin and resistin through its activation of ER stress, which may be related to the increase of cholesterol load in adipocytes. PMID:24278099

Chen, Yaqin; Chen, Mingjie; Wu, Zhihong; Zhao, Shuiping

2013-01-01

61

Estrogen receptor (? and ?) but not androgen receptor expression is correlated with recurrence, progression and survival in post prostatectomy T3N0M0 locally advanced prostate cancer in an urban Greek population  

PubMed Central

The objective of this study was to evaluate the expression of estrogen receptors (ER(?) and ER(?)) and androgen receptors (ARs) as prognostic factors for biochemical recurrence, disease progression and survival in patients with pT3N0M0 prostate cancer (PCa) in an urban Greek population. A total of 100 consecutive patients with pT3N0M0 PCa treated with radical prostatectomy participated in the study. The mean age and follow-up were 64.2 and 6 years, respectively. The HSCORE was used for semi-quantitative analysis of the immunoreactivity of the receptors. The prognostic value of the ER(?) and ER(?) and AR was assessed in terms of recurrence, progression, and survival. AR expression was not associated with any of the above parameters; however, both ERs correlated with the prognosis. A univariate Cox regression analysis showed that ER(?) positive staining was significantly associated with a greater hazard for all outcomes. Increased ER(?) staining was significantly associated with a lower hazard for all outcomes in the univariate analysis. When both ER HSCORES were used for the analysis, it was found that patients with high ER(?) or low ER(?) HSCORES compared with patients with negatively stained ER(?) and >1.7 hSCORE ER(?) had 6.03, 10.93, and 10.53 times greater hazard for biochemical disease recurrence, progression of disease and death, respectively. Multiple Cox proportional hazard analyses showed that the age, preoperative prostate specific antigen, Gleason score and ERs were independent predictors of all outcomes. ER expression is an important prognosticator after radical prostatectomy in patients with pT3N0M0 PCa. By contrast, AR expression has limited prognostic value. PMID:25219910

Megas, Georgios; Chrisofos, Michael; Anastasiou, Ioannis; Tsitlidou, Aida; Choreftaki, Theodosia; Deliveliotis, Charalampos

2015-01-01

62

Antisense RNA--Induced Reduction in Murine TIMP Levels Confers Oncogenicity on Swiss 3T3 Cells  

Microsoft Academic Search

Mouse 3T3 cell lines capable of constitutively synthesizing an RNA complementary to the messenger RNA encoding TIMP, tissue inhibitor of metalloproteinases, were constructed by transfection with appropriate plasmid constructs. Many of the lines were down-modulated for TIMP messenger RNA levels and secreted less TIMP into the culture medium. In comparison to noninvasive, nontumorigenic controls, these cells not only were invasive

Rama Khokha; Paul Waterhouse; Simcha Yagel; Peeyush K. Lala; Christopher M. Overall; Gill Norton; David T. Denhardt

1989-01-01

63

Quercetin reversed lipopolysaccharide-induced inhibition of osteoblast differentiation through the mitogen?activated protein kinase pathway in MC3T3-E1 cells.  

PubMed

Quercetin, a flavonoid found in onions and other vegetables, has potential inhibitory effects on bone resorption in vivo and in vitro. In our previous study it was identified that quercetin triggered the apoptosis of lipopolysaccharide (LPS)?induced osteoclasts and inhibited bone resorption. Currently, little information is available detailing the effect of quercetin on osteoblast differentiation and bone formation in bacteria?induced inflammatory diseases. The present study aimed to investigate the effect of quercetin on osteoblast differentiation in MC3T3?E1 osteoblasts stimulated with LPS. LPS significantly downregulated the mRNA expression of osteoblast?related genes in the MC3T3?E1 cells. By contrast, quercetin significantly restored the LPS?suppressed mRNA expression of osteoblast?related genes in a dose?dependent manner. Quercetin also restored the protein expression of Osterix in MC3T3?E1 cells suppressed by LPS. Furthermore, quercetin selectively triggered the activation of the mitogen?activated protein kinase (MAPK) pathway by enhancing the expression of extracellular signal-regulated kinase and reducing the expression of c?Jun N?terminal kinase. These data suggest that quercetin reversed the inhibition of osteoblast differentiation induced by LPS through MAPK signaling. These findings suggest that quercetin may be of potential use as a therapeutic agent to restore osteoblast function in bacteria?induced bone diseases. PMID:25323558

Wang, Xin-Chun; Zhao, Nzhi-Jun; Guo, Chun; Chen, Jing-Tao; Song, Jin-Ling; Gao, Li

2014-12-01

64

Proinflammatory effects of arachidonic acid in a lipopolysaccharide-induced inflammatory microenvironment in 3T3-L1 adipocytes in vitro.  

PubMed

Long-chain n-3 polyunsaturated fatty acids (PUFA), eicosapentaenoic acid (20:5n-3, EPA) and docosahexaenoic acid (22:6n-3, DHA), have known anti-inflammatory effects, including the modulation of adipose tissue-derived inflammatory mediators (i.e., adipokines) implicated in obesity-related pathologies, such as insulin resistance. Less is known about the effects of plant-derived n-3 PUFA, ?-linolenic acid (ALA, 18:3n-3) and stearidonic acid (SDA 18:4n-3), or n-6 PUFA linoleic acid (LA, 18:2n-6) and arachidonic acid (AA, 20:4n-6), especially in combination with an inflammatory stimulus, such as lipopolysaccharide (LPS), at a dose intended to mimic obesity-associated low-grade inflammation. To study this, 3T3-L1 adipocytes were incubated with 100 ?mol/L of various n-3 or n-6 PUFA with or without 10 ng/mL LPS for up to 24 h. AA in the presence of LPS synergistically increased (p < 0.05) pro-inflammatory monocyte chemoattractant protein-1 (MCP)-1 and interleukin (IL)-6 secretion and gene expression, as well as COX-2 and TLR2 gene expression at 6 and/or 24 h, suggesting their potential roles in the synergistic effects of AA and LPS. Plant-derived fatty acids ALA, SDA, and LA did not differentially affect adipokine gene expression or secretion, whereas LPS-induced pro-inflammatory IL-1? expression and MCP-1 secretion was decreased (p < 0.05) by EPA, DHA, and/or EPA+DHA (50 ?mol/L each) compared with LPS alone. Only DHA increased (p < 0.05) gene expression of the n-3 PUFA receptor GPR120 and simultaneously decreased LPS-induced nuclear factor-?B activation compared with control. Our findings emphasize that specific fatty acids within the n-3 or n-6 PUFA class warrant consideration in the development of nutritional strategies to improve obesity-associated inflammation. PMID:25641170

Cranmer-Byng, Mary M; Liddle, Danyelle M; De Boer, Anna A; Monk, Jennifer M; Robinson, Lindsay E

2015-02-01

65

Activation of AMPK participates hydrogen sulfide-induced cyto-protective effect against dexamethasone in osteoblastic MC3T3-E1 cells.  

PubMed

Long-time glucocorticoids (GCs) usage causes osteoporosis. In the present study, we explored the potential role of hydrogen sulfide (H2S) against dexamethasone (Dex)-induced osteoblast cell damage, and focused on the underlying mechanisms. We showed that two H2S-producing enzymes, cystathionine ?-synthase (CBS) and cystathionine ?-lyase (CSE), were significantly downregulated in human osteonecrosis tissues as well as in Dex-treated osteoblastic MC3T3-E1 cells. H2S donor NaHS as well as the CBS activator S-adenosyl-l-methionine (SAM) inhibited Dex-induced viability reduction, death and apoptosis in MC3T3-E1 cells. NaHS activated adenosine monophosphate (AMP)-activated protein kinase (AMPK) signaling, which participated its cyto-protective activity. AMPK inhibition by its inhibitor (compound C) or reduction by targeted-shRNA suppressed its pro-survival activity against Dex in MC3T3-E1 cells. Further, we found that NaHS inhibited Dex-mediated reactive oxygen species (ROS) production and ATP depletion. Such effects by NaHS were again inhibited by compound C and AMPK?1-shRNA. In summary, we show that H2S inhibits Dex-induced osteoblast damage through activation of AMPK signaling. H2S signaling might be further investigated as a novel target for anti-osteoporosis treatment. PMID:25445596

Yang, Ming; Huang, Yue; Chen, Jia; Chen, Yi-Lei; Ma, Jian-Jun; Shi, Pei-Hua

2014-10-14

66

Concentration-dependent stimulatory and inhibitory effect of troglitazone on insulin-induced fatty acid synthase expression and protein kinase B activity in 3T3-L1 adipocytes.  

PubMed

In order to study the effect of the peroxisome proliferator-activated receptor gamma (PPARgamma) agonist troglitazone on the insulin-induced expression of fatty acid synthase (FAS) in adipocytes, we generated a 3T3-L1 cell line stably expressing a FAS reporter gene construct. In this cell line, a low concentration of troglitazone (250 nM) increased the effect of insulin on the FAS promoter activity and the expression of FAS protein about 1.5- to 2-fold. Since the effect of insulin on the expression of FAS is believed to be mediated by activation of protein kinase B (PKB), we investigated the effect of troglitazone on the regulation of PKB. Troglitazone (250 nM) increased the maximal effect of insulin on PKB activity about twofold without significantly affecting its EC(50) (1.4+/-0.5 nM vs. 2.2+/-0.6 nM in controls). Higher concentrations of troglitazone (> or =1 microM) inhibited both insulin-stimulated PKB activity and expression of FAS. In summary, our data indicate a dual effect of troglitazone on the insulin-induced FAS gene expression in 3T3-L1 cells. The therapeutic, stimulatory effect is produced by low concentrations of troglitazone (250 nM), and is presumably mediated by enhanced activation of PKB. PMID:11919653

Barthel, Andreas; Krüger, Klaus-Dieter; Roth, Richard A; Joost, Hans-Georg

2002-04-01

67

Activation of AMP-Activated Protein Kinase Attenuates Tumor Necrosis Factor-?-Induced Lipolysis via Protection of Perilipin in 3T3-L1 Adipocytes  

PubMed Central

Background Tumor necrosis factor (TNF)-? and AMP-activated protein kinase (AMPK) are known to stimulate and repress lipolysis in adipocytes, respectively; however, the mechanisms regulating these processes have not been completely elucidated. Methods The key factors and mechanism of action of TNF-? and AMPK in lipolysis were investigated by evaluating perilipin expression and activity of protein kinase RNA-like endoplasmic reticulum kinase (PERK)/eukaryotic initiation factor 2 ? (eIF2?) by Western blot and an immunofluorescence assay in 24-hour TNF-?-treated 3T3-L1 adipocytes with artificial manipulation of AMPK activation. Results Enhancement of AMPK activity by the addition of activator minoimidazole carboxamide ribonucleotide (AICAR) suppressed TNF-?-induced lipolysis, whereas the addition of compound C, an inhibitor of AMPK phosphorylation, enhanced lipolysis. Perilipin, a lipid droplet-associated protein, was decreased by TNF-? and recovered following treatment with AICAR, showing a correlation with the antilipolytic effect of AICAR. Significant activation of PERK/eIF2?, a component of the unfolded protein response signaling pathway, was observed in TNF-? or vesicle-treated 3T3-L1 adipocytes. The antilipolytic effect and recovery of perilipin expression by AICAR in TNF-?-treated 3T3-L1 adipocytes were significantly diminished by treatment with 2-aminopurine, a specific inhibitor of eIF2?. Conclusion These data indicated that AICAR-induced AMPK activation attenuates TNF-?-induced lipolysis via preservation of perilipin in 3T3-L1 adipocytes. In addition, PERK/eIF2? activity is a novel mechanism of the anti-lipolytic effect of AICAR.

Hong, Seok-Woo; Lee, Jinmi; Park, Se Eun; Rhee, Eun-Jung; Park, Cheol-Young; Oh, Ki-Won; Park, Sung-Woo

2014-01-01

68

Blueberry Peel Extracts Inhibit Adipogenesis in 3T3-L1 Cells and Reduce High-Fat Diet-Induced Obesity  

PubMed Central

This study examined the anti-obesity effect and mechanism of action of blueberry peel extracts (BPE) in 3T3-L1 cells and high-fat diet (HFD)-induced obese rats. The levels of lipid accumulation were measured, along with the changes in the expression of genes and proteins associated with adipocyte differentiation in 3T3-L1 cells. Evidenced by Oil-red O staining and triglyceride assay, BPE dose-dependently inhibited lipid accumulation at concentrations of 0, 50, and 200 µg/ml. BPE decreased the expression of the key adipocyte differentiation regulator C/EBP?, as well as the C/EBP? and PPAR? genes, during the differentiation of preadipocytes into adipocytes. Moreover, BPE down-regulated adipocyte-specific genes such as aP2 and FAS compared with control adipocytes. The specific mechanism mediating the effects of BP revealed that insulin-stimulated phosphorylation of Akt was strongly decreased, and its downstream substrate, phospho-GSK3?, was downregulated by BPE treatment in 3T3-L1 cells. Together, these data indicated that BP exerted anti-adipogenic activity by inhibiting the expression of PPAR? and C/EBP? and the Akt signaling pathway in 3T3-L1 adipocytes. Next, we investigated whether BP extracts attenuated HFD-induced obesity in rats. Oral administration of BPE reduced HFD-induced body weight gain significantly without affecting food intake. The epididymal or perirenal adipose tissue weights were lower in rats on an HFD plus BPE compared with the tissue weights of HFD-induced obese rats. Total cholesterol and triglyceride levels in the rats fed BPE were modestly reduced, and the HDL-cholesterol level was significantly increased in HFD plus BP-fed rats compared with those of HFD-fed rats. Taken together, these results demonstrated an inhibitory effect of BP on adipogenesis through the down-regulation of C/EBP?, C/EBP?, and PPAR? and the reduction of the phospho-Akt adipogenic factor in 3T3-L1 cells. Moreover, BPE reduced body weight gain and inhibited fat accumulation in an HFD-induced animal model of obesity. PMID:23936120

Jang, Sun-Hee; Lee, Soo-Jung; Ko, Yeoung-Gyu; Kim, Gon-Sup; Cho, Jae-Hyeon

2013-01-01

69

Ajoene exerts potent effects in 3T3-L1 adipocytes by inhibiting adipogenesis and inducing apoptosis.  

PubMed

This paper describes effects of several sulfur-containing compounds from garlic on the cell viability, apoptosis and adipogenesis in 3T3-L1 adipocytes. In both preadipocytes and mature adipocytes, 100 and 200 microM ajoene significantly decreased cell viability and increased apoptosis. The effect on apoptosis was further confirmed with Hoechst staining. In contrast, diallyl sulfide, diallyl disulfide, diallyl trisulfide, deoxyalliin, and allyl methyl sulfide had no significant effect on cell viability or apoptosis in either preadipocytes or mature adipocytes. In maturing preadipocytes ajoene significantly decreased lipid accumulation in a dose-dependent manner and these results were further confirmed by a decrease in lipid droplet number and lipid content through Oil Red O staining. There was no significant change in lipid accumulation in maturing preadipocytes treated with other garlic derivatives. Thus, despite the same source of origin, garlic, ajoene was the only one with potent effects on cell viability, apoptosis and adipogenesis in 3T3-L1 adipocytes. PMID:19051208

Ambati, Suresh; Yang, Jeong-Yeh; Rayalam, Srujana; Park, Hea Jin; Della-Fera, Mary Anne; Baile, Clifton A

2009-04-01

70

Piperine, a component of black pepper, decreases eugenol-induced cAMP and calcium levels in non-chemosensory 3T3-L1 cells  

PubMed Central

This study investigated the effects of an ethanol extract of black pepper and its constituent, piperine, on odorant-induced signal transduction in non-chemosensory cells. An ethanol extract of black pepper decreased eugenol-induced cAMP and calcium levels in preadipocyte 3T3-L1 cells with no toxicity. Phosphorylation of CREB (cAMP response element-binding protein) was down-regulated by the black pepper extract. The concentration (133.8 mg/g) and retention time (5.5 min) of piperine in the ethanol extract were quantified using UPLC–MS/MS. Pretreatment with piperine decreased eugenol-induced cAMP and calcium levels in 3T3-L1 cells. Piperine also decreased the phosphorylation of CREB, which is up-regulated by eugenol. These results suggest that piperine inhibits the eugenol-induced signal transduction pathway through modulation of cAMP and calcium levels and phosphorylation of CREB in non-chemosensory cells.

Yoon, Yeo Cho; Kim, Sung-Hee; Kim, Min Jung; Yang, Hye Jeong; Rhyu, Mee-Ra; Park, Jae-Ho

2014-01-01

71

Expression of Caveolin-1 reduces cellular responses to TGF-{beta}1 through down-regulating the expression of TGF-{beta} type II receptor gene in NIH3T3 fibroblast cells  

SciTech Connect

Transcriptional repression of Transforming Growth Factor-{beta} type II receptor (T{beta}RII) gene has been proposed to be one of the major mechanisms leading to TGF-{beta} resistance. In this study, we demonstrate that expression of Caveolin-1 (Cav-1) gene in NIH3T3 fibroblast cells down-regulates the expression of T{beta}RII gene in the transcriptional level, eventually resulting in the decreased responses to TGF-{beta}. The reduced expression of T{beta}RII gene by Cav-1 appeared to be due to the changes of the sequence-specific DNA binding proteins to either Positive Regulatory Element 1 (PRE1) or PRE2 of the T{beta}RII promoter. In addition, Cav-1 expression inhibited TGF-{beta}-mediated cellular proliferation and Plasminogen Activator Inhibitor (PAI)-1 gene expression as well as TGF-{beta}-induced luciferase activity. Furthermore, the inhibition of endogeneous Cav-1 by small interfering RNA increased the expression of T{beta}RII gene. These findings strongly suggest that expression of Cav-1 leads to the decreased cellular responsiveness to TGF-{beta} through down-regulating T{beta}RII gene expression.

Lee, Eun Kyung [Inha University College of Medicine, Incheon 400-121 (Korea, Republic of); Lee, Youn Sook [Department of Biological Science, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Han, In-Oc [Inha University College of Medicine, Incheon 400-121 (Korea, Republic of); Park, Seok Hee [Inha University College of Medicine, Incheon 400-121 (Korea, Republic of) and Department of Biological Science, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)]. E-mail: parks@skku.edu

2007-07-27

72

The ?-SiC Nanowires (~100 nm) Induce Apoptosis via Oxidative Stress in Mouse Osteoblastic Cell Line MC3T3-E1  

PubMed Central

Silicon carbide (SiC), a compound of silicon and carbon, with chemical formula SiC, the beta modification (?-SiC), with a zinc blende crystal structure (similar to diamond), is formed at temperature below 1700°C. ?-SiC will be the most suitable ceramic material for the future hard tissue replacement, such as bone and tooth. The in vitro cytotoxicity of ?-SiC nanowires was investigated for the first time. Our results indicated that 100?nm long SiC nanowires could significantly induce the apoptosis in MC3T3-E1 cells, compared with 100??m long SiC nanowires. And 100?nm long SiC nanowires increased oxidative stress in MC3T3-E1 cells, as determined by the concentrations of MDA (as a marker of lipid peroxidation) and 8-OHdG (indicator of oxidative DNA damage). Moreover, transmission electron microscopy (TEM) was performed to evaluate the morphological changes of MC3T3-E1 cells. After treatment with 100?nm long SiC nanowires, the mitochondria were swelled and disintegrated, and the production of ATP and the total oxygen uptake were also decreased significantly. Therefore, ?-SiC nanowires may have limitations as medical material. PMID:24967352

Xie, Weili; Xie, Qi; Jin, Meishan; Huang, Xiaoxiao; Zhang, Xiaodong; Shao, Zhengkai; Wen, Guangwu

2014-01-01

73

Sucrose Ingestion Induces Rapid AMPA Receptor Trafficking  

PubMed Central

The mechanisms by which natural rewards such as sugar affect synaptic transmission and behavior are largely unexplored. Here, we investigate regulation of nucleus accumbens synapses by sucrose intake. Previous studies have shown that AMPA receptor trafficking is a major mechanism for regulating synaptic strength, and that in vitro, trafficking of AMPA receptors containing the GluA1 subunit takes place by a two-step mechanism involving extrasynaptic and then synaptic receptor transport. We report that in rat, repeated daily ingestion of a 25% sucrose solution transiently elevated spontaneous locomotion and potentiated accumbens core synapses through incorporation of Ca2+-permeable AMPA receptors (CPARs), which are GluA1-containing, GluA2-lacking AMPA receptors. Electrophysiological, biochemical and quantitative electron microscopy studies revealed that sucrose training (7 days) induced a stable (>24 hr) intraspinous GluA1 population, and that in these rats a single sucrose stimulus rapidly (5 min) but transiently (<24 hr) elevated GluA1 at extrasynaptic sites. CPARs and dopamine D1 receptors were required in vivo for elevated locomotion after sucrose ingestion. Significantly, a 7-day protocol of daily ingestion of a 3% solution of saccharin, a non-caloric sweetener, induced synaptic GluA1 similarly to 25% sucrose ingestion. These findings identify multi-step GluA1 trafficking, previously described in vitro, as a mechanism for acute regulation of synaptic transmission in vivo by a natural orosensory reward. Trafficking is stimulated by a chemosensory pathway that is not dependent on the caloric value of sucrose. PMID:23554493

Tukey, David S.; Ferreira, Jainne M.; Antoine, Shannon O.; D’amour, James A.; Ninan, Ipe; de Vaca, Soledad Cabeza; Incontro, Salvatore; Wincott, Charlotte; Horwitz, Julian K.; Hartner, Diana T.; Guarini, Carlo B.; Khatri, Latika; Goffer, Yossef; Xu, Duo; Titcombe, Roseann F.; Khatri, Megna; Marzan, Dave S.; Mahajan, Shahana S.; Wang, Jing; Froemke, Robert C.; Carr, Kenneth D.; Aoki, Chiye; Ziff, Edward B.

2013-01-01

74

Increased cell proliferation of mouse fibroblast NIH-3T3 in vitro induced by excretory/secretory product(s) from Opisthorchis viverrini.  

PubMed

Infection by Opisthorchis viverrini is a strong risk factor for cholangiocarcinoma. However, the mechanism by which the parasite is involved in carcinogenesis is not clear. In addition to the direct damage of the bile duct epithelium via direct contact with O. viverrini, the excretory/secretory (ES) product(s) released from the parasites may play important roles in this process. We therefore investigated the responses of a fibroblast cell line, NIH-3T3, to ES product(s) released from O. viverrini by using a non-contact co-culture technique. In this culture system, the parasites in the upper chamber had no direct contact with the NIH-3T3 cells in the lower chamber of the culture plate. The results indicated a marked increase in NIH-3T3 cell proliferation in the non-contact co-culture condition with either 0% or 10% calf serum in the medium compared with that without parasites. ES product(s) increased cell proliferation by stimulating the expression of phosphorylated retinoblastoma (pRB) and cyclin D1, the key proteins in driving cells through the G1/S transition point of the cell cycle. This led to the induction of cells going into the S-phase of the cell cycle. ES product(s) also changed the morphology of NIH-3T3 cells to a refractive and narrow shape, which allowed the cells to proliferate in the limited culture area. For the first time, we have been able to demonstrate increased cell proliferation induced by the ES product(s) from O. viverrini; this finding may clarify how O. viverrini ES product(s) affect human bile duct epithelium during cholangiocarcinogenesis. PMID:15521634

Thuwajit, C; Thuwajit, P; Kaewkes, S; Sripa, B; Uchida, K; Miwa, M; Wongkham, S

2004-10-01

75

Amelioration of Mitochondrial Dysfunction-Induced Insulin Resistance in Differentiated 3T3-L1 Adipocytes via Inhibition of NF-?B Pathways  

PubMed Central

A growing body of evidence suggests that activation of nuclear factor kappa B (NF-?B) signaling pathways is among the inflammatory mechanism involved in the development of insulin resistance and chronic low-grade inflammation in adipose tissues derived from obese animal and human subjects. Nevertheless, little is known about the roles of NF-?B pathways in regulating mitochondrial function of the adipose tissues. In the present study, we sought to investigate the direct effects of celastrol (potent NF-?B inhibitor) upon mitochondrial dysfunction-induced insulin resistance in 3T3-L1 adipocytes. Celastrol ameliorates mitochondrial dysfunction by altering mitochondrial fusion and fission in adipocytes. The levels of oxidative DNA damage, protein carbonylation and lipid peroxidation were down-regulated. Further, the morphology and quantification of intracellular lipid droplets revealed the decrease of intracellular lipid accumulation with reduced lipolysis. Moreover, massive production of the pro-inflammatory mediators tumor necrosis factor-? (TNF-?) and interleukin-1? (IL-1?) were markedly depleted. Insulin-stimulated glucose uptake activity was restored with the enhancement of insulin signaling pathways. This study signified that the treatments modulated towards knockdown of NF-?B transcription factor may counteract these metabolic insults exacerbated in our model of synergy between mitochondrial dysfunction and inflammation. These results demonstrate for the first time that NF-?B inhibition modulates mitochondrial dysfunction induced insulin resistance in 3T3-L1 adipocytes. PMID:25474091

Hafizi Abu Bakar, Mohamad; Sarmidi, Mohamad Roji; Kai, Cheng Kian; Huri, Hasniza Zaman; Yaakob, Harisun

2014-01-01

76

Oroxylin A, a constituent of Oroxylum indicum inhibits adipogenesis and induces apoptosis in 3T3-L1 cells.  

PubMed

Oroxylin A (OA) is a flavonoid found in Oroxylum indicum, a medicinal plant with multiple biological activities. This study was taken up to investigate the effect of OA, on adipogenesis, lipolysis and apoptosis in 3T3 L1 cells. Pre-adipocytes were treated with 10-40?M OA on various days of adipogenesis treatment schedule. Mature adipocytes were treated with OA for lipolysis and apoptosis studies. In maturing pre-adipocytes, 10?M OA suppressed intracellular lipid accumulation by 42.19% which was confirmed by lipidTox imaging of cells. In addition, OA decreased the nuclear translocation of PPAR? and mRNA expression of its downstream genes (FAS and LPL) along with adiponectin secretion. In mature adipocytes, 40?M of OA decreased cell viability by 30% of control. Annexin V/PI staining showed induction of apoptosis which was further confirmed by enhanced levels of pro-apoptotic proteins Bax, cyt c, AIF and chromatin condensation. OA enhanced TNF-? secretion, lipolysis and decreased Akt phosphorylation in mature adipocytes. Findings suggest that OA possibly exerts its anti-obesity effect by affecting adipocyte life cycle at critical points of differentiation and maturity. When we compared the potency of OA with non-methoxylated flavonoids morin, naringenin and kaempferol on adipocyte life cycle OA was far more potent. Thus, study clearly indicates a new role for oroxylin A as regulator of adipocyte life cycle. In addition, study also suggested a specific role of methoxylated group in exerting lipolysis and cytotoxic effects in mature adipocytes. PMID:25442284

Singh, Jyotsna; Kakkar, Poonam

2014-10-15

77

MicroRNA-1 Participates in Nitric Oxide-Induced Apoptotic Insults to MC3T3-E1 Cells by Targeting Heat-Shock Protein-70  

PubMed Central

Our previous studies showed that nitric oxide (NO) could induce osteoblast apoptosis. MicroRNA-1 (miR-1), a skeletal- and cardiac muscle-specific small non-coding RNA, contributes to the regulation of multiple cell activities. In this study, we evaluated the roles of miR-1 in NO-induced insults to osteoblasts and the possible mechanisms. Exposure of mouse MC3T3-E1 cells to sodium nitroprusside (SNP) increased amounts of cellular NO and intracellular reactive oxygen species. Sequentially, SNP decreased cell survival but induced caspase-3 activation, DNA fragmentation, and cell apoptosis. In parallel, treatment with SNP induced miR-1 expression in a time-dependent manner. Application of miR-1 antisense inhibitors to osteoblasts caused significant inhibition of SNP-induced miR-1 expression. Knocking down miR-1 concurrently attenuated SNP-induced alterations in cell morphology and survival. Consecutively, SNP time-dependently inhibited heat-shock protein (HSP)-70 messenger (m)RNA and protein expressions. A bioinformatic search predicted the existence of miR-1-specific binding elements in the 3'-untranslational region of HSP-70 mRNA. Downregulation of miR-1 expression simultaneously lessened SNP-induced inhibition of HSP-70 mRNA and protein expressions. Consequently, SNP-induced modifications in the mitochondrial membrane potential, caspase-3 activation, DNA fragmentation, and apoptotic insults were significantly alleviated by miR-1 antisense inhibitors. Therefore, this study showed that miR-1 participates in NO-induced apoptotic insults through targeting HSP-70 gene expression.

Lee, Yong-Eng; Hong, Chung-Ye; Lin, Yi-Ling; Chen, Ruei-Ming

2015-01-01

78

Sucrose ingestion induces rapid AMPA receptor trafficking.  

PubMed

The mechanisms by which natural rewards such as sugar affect synaptic transmission and behavior are largely unexplored. Here, we investigate regulation of nucleus accumbens synapses by sucrose intake. Previous studies have shown that AMPA receptor (AMPAR) trafficking is a major mechanism for regulating synaptic strength, and that in vitro, trafficking of AMPARs containing the GluA1 subunit takes place by a two-step mechanism involving extrasynaptic and then synaptic receptor transport. We report that in rat, repeated daily ingestion of a 25% sucrose solution transiently elevated spontaneous locomotion and potentiated accumbens core synapses through incorporation of Ca(2+)-permeable AMPA receptors (CPARs), which are GluA1-containing, GluA2-lacking AMPARs. Electrophysiological, biochemical, and quantitative electron microscopy studies revealed that sucrose training (7 d) induced a stable (>24 h) intraspinous GluA1 population, and that in these rats a single sucrose stimulus rapidly (5 min) but transiently (<24 h) elevated GluA1 at extrasynaptic sites. CPARs and dopamine D1 receptors were required in vivo for elevated locomotion after sucrose ingestion. Significantly, a 7 d protocol of daily ingestion of a 3% solution of saccharin, a noncaloric sweetener, induced synaptic GluA1 similarly to 25% sucrose ingestion. These findings identify multistep GluA1 trafficking, previously described in vitro, as a mechanism for acute regulation of synaptic transmission in vivo by a natural orosensory reward. Trafficking is stimulated by a chemosensory pathway that is not dependent on the caloric value of sucrose. PMID:23554493

Tukey, David S; Ferreira, Jainne M; Antoine, Shannon O; D'amour, James A; Ninan, Ipe; Cabeza de Vaca, Soledad; Incontro, Salvatore; Wincott, Charlotte; Horwitz, Julian K; Hartner, Diana T; Guarini, Carlo B; Khatri, Latika; Goffer, Yossef; Xu, Duo; Titcombe, Roseann F; Khatri, Megna; Marzan, Dave S; Mahajan, Shahana S; Wang, Jing; Froemke, Robert C; Carr, Kenneth D; Aoki, Chiye; Ziff, Edward B

2013-04-01

79

Melatonin rescues 3T3-L1 adipocytes from FFA-induced insulin resistance by inhibiting phosphorylation of IRS-1 on Ser307.  

PubMed

Melatonin is biosynthesized in the pineal gland and secreted into the bloodstream. Evidences indicate a role of melatonin in the regulation of glucose metabolism. The objective of this study was to investigate the effect of melatonin on insulin sensitivity in insulin resistant adipocytes. Following a preincubation with melatonin or vehicle for 30 min, insulin resistant cells of 3T3-L1 adipocytes were induced by palmitic acids (300 ?M, 6 h). Our results showed that palmitic acids inhibited both the basal and insulin-stimulated uptake of [(3)H]-2-Deoxyglucose, down-regulated the levels of IRS-1 and GLUT-4. However, compared to the vehicle group, melatonin pre-treatment increased significantly the uptake of [(3)H]-2-Deoxyglucose as well as the level of GLUT-4, and decreased phosphorylated IRS-1 (Ser307) although total IRS-1 did not change significantly. These data suggest that palmitic acids impair insulin signal via down-regulating the expressions of IRS-1 and GLUT-4; whereas melatonin can ameliorate insulin sensitivity by inhibiting Ser307 phosphorylation in IRS-1 and increasing GLUT-4 expressions in insulin resistant 3T3-L1 adipocytes. We conclude that melatonin regulates the insulin sensitivity and glucose homeostasis via inhibiting Ser-phosphorylation and improving function of IRS-1. PMID:24846082

She, Meihua; Hou, Hongjie; Wang, Zongbao; Zhang, Chi; Laudon, Moshe; Yin, Weidong

2014-08-01

80

Down-regulation of cyclic-nucleotide phosphodiesterase 3B in 3T3-L1 adipocytes induced by tumour necrosis factor alpha and cAMP.  

PubMed Central

We have used murine 3T3-L1 cells, which differentiate in culture and acquire morphological and biochemical features of mature adipocytes, as a model for studying the expression of cyclic-nucleotide phosphodiesterase (PDE) 3B activity, protein and mRNA during differentiation and during long-term treatment of the cells with tumour necrosis factor alpha (TNF-alpha), a cytokine associated with insulin resistance, and a cAMP analogue, N(6),2'-O-dibutyryl cAMP (dbcAMP). PDE3B activity, protein and mRNA could be detected 4 days after the initiation of differentiation of 3T3-L1 preadipocytes. Treatment of 3T3-L1 adipocytes with 10 ng/ml TNF-alpha for 24 h produced a maximal (50%) decrease in PDE3B activity, protein and mRNA, which was well correlated with both activation of protein kinase A (PKA) and stimulation of lipolysis, presumably reflecting an increase in intracellular cAMP concentration. To investigate the effect of cAMP on PDE3B we treated 3T3-L1 adipocytes with dbcAMP. After 4 h with 0.5 mM dbcAMP, PDE3B activity was decreased by 80%, which was also correlated with a decrease in PDE3B protein and mRNA. This effect was abolished in the presence of N-[2-(bromocinnamylamino)ethyl]-5-isoquinolinesulphonamide] (H-89), a specific PKA inhibitor. We conclude that the lipolytic effect of TNF-alpha involves the down-regulation of PDE3B, which is associated with increased activation of PKA, presumably owing to increased levels of cAMP. In addition, the PKA activation induced by dbcAMP resulted in the down-regulation of PDE3B. These results, which suggest that PDE3B is a novel target for long-term regulation by TNF-alpha and cAMP, could contribute to the understanding of the mechanisms of insulin resistance. PMID:10677351

Rahn Landström, T; Mei, J; Karlsson, M; Manganiello, V; Degerman, E

2000-01-01

81

Correlations between radiation-induced double strand breaks, cell division delay, and cyclin-dependent signaling in x-irradiated NIH3T3 fibroblasts  

NASA Astrophysics Data System (ADS)

Molecular responses to radiation-induced DNA double strand breaks (DSB) are mediated by the phosphorylation of the histone variant H2AX which forms identifiable gamma-H2AX foci at the site of the DSB. This event is thought to be linked with the down-regulation of signaling proteins contributing to the checkpoints regulating cell cycle progression and, vis-a-vis , the induction of cell division delay. However, it is unclear whether this division delay is directly related to the number of DSB (gamma-H2AX foci) sustained by an irradiated cell and, if so, whether this number drives cells into cell cycle delay or apoptosis. For this reason, studies were conducted in the immortalized NIH/3T3 fibroblast cell in order to establish correlations between the temporal appearance of the gamma-H2AX foci (a DSB) and the expression of the cell cycle regulatory proteins, cyclin E, A, B1, and their cyclin kinase inhibitor, p21. Cell cycle kinetics and flow cytometry were used to establish radiation-induced division delay over a dose range of 1--6 Gy where a mitotic delay of 2.65 min/cGy was established. Correlations between the expression of cyclin E, A, B1, p21, and the generation of DSB were established in NIH/3T3 cells exposed to 2 or 4 Gy x-irradiation. The data suggest that the G1/S and S phase delay (cyclin E and cyclin A protein levels) are dependent on the dose of radiation while the G2/M (cyclin B1 protein levels) delay is dependent on the quantity of DSB sustained by the irradiated cell.

Cariveau, Mickael J.

2005-07-01

82

T3 (Triiodothyronine) Test  

MedlinePLUS

... more information, see the Thyroid Foundation of America's web page Thyroid Problems During and After Pregnancy - Are You At Risk? ^ Back to top 2. What is the T3 uptake test? This test was once used to help calculate ...

83

Soluble Receptor-Induced Retroviral Infection of Receptor-Deficient Cells  

Microsoft Academic Search

Current models of retroviral entry hypothesize that interactions between the host cell receptor(s) and viral envelope protein induce structural changes in the envelope protein that convert it to an active conformation, allowing it to mediate fusion with the membrane. Recent evidence supporting this hypothesis is the demon- stration that Tva, the receptor for subgroup A avian sarcoma and leukosis virus

RACHEL DAMICO; PAUL BATES

2000-01-01

84

A short pulse of mechanical force induces gene expression and growth in MC3T3-E1 osteoblasts via an ERK 1/2 pathway  

NASA Technical Reports Server (NTRS)

Physiological mechanical loading is crucial for maintenance of bone integrity and architecture. We have calculated the strain caused by gravity stress on osteoblasts and found that 4-30g corresponds to physiological levels of 40-300 microstrain. Short-term gravity loading (15 minutes) induced a 15-fold increase in expression of growth-related immediate early gene c-fos, a 5-fold increase in egr-1, and a 3-fold increase in autocrine bFGF. The non-growth-related genes EP-1, TGF-beta, and 18s were unaffected by gravity loading. Short-term physiological loading induced extracellular signal-regulated kinase (ERK 1/2) phosphorylation in a dose-dependent manner with maximum phosphorylation saturating at mechanical loading levels of 12g (p < 0.001) with no effect on total ERK. The phosphorylation of focal adhesion kinase (FAK) was unaffected by mechanical force. g-Loading did not activate P38 MAPK or c-jun N-terminal kinase (JNK). Additionally, a gravity pulse resulted in the localization of phosphorylated ERK 1/2 to the nucleus; this did not occur in unloaded cells. The induction of c-fos was inhibited 74% by the MEK1/2 inhibitor U0126 (p < 0.001) but was not affected by MEK1 or p38 MAPK-specific inhibitors. The long-term consequence of a single 15-minute gravity pulse was a 64% increase in cell growth (p < 0.001). U0126 significantly inhibited gravity-induced growth by 50% (p < 0.001). These studies suggest that short periods of physiological mechanical stress induce immediate early gene expression and growth in MC3T3-E1 osteoblasts primarily through an ERK 1/2-mediated pathway.

Hatton, Jason P.; Pooran, Milad; Li, Chai-Fei; Luzzio, Chris; Hughes-Fulford, Millie

2003-01-01

85

Impact of lipid phosphatases SHIP2 and PTEN on the time- and Akt-isoform-specific amelioration of TNF-alpha-induced insulin resistance in 3T3-L1 adipocytes.  

PubMed

TNF-alpha is a major contributor to the pathogenesis of insulin resistance associated with obesity and inflammation by serine phosphorylating and degrading insulin receptor substrate-1. Presently, we further found that pretreatment with TNF-alpha inhibited insulin-induced phosphorylation of Akt2 greater than Akt1. Since lipid phosphatases SH2-containing inositol 5'-phoshatase 2 (SHIP2) and phosphatase and tensin homologs deleted on chromosome 10 (PTEN) are negative regulators of insulin's metabolic signaling at the step downstream of phosphatidylinositol 3-kinase, we investigated the Akt isoform-specific properties of these phosphatases in the negative regulation after short- and long-term insulin treatment and examined the influence of inhibition on the amelioration of insulin resistance caused by TNF-alpha in 3T3-L1 adipocytes. Adenovirus-mediated overexpression of WT-SHIP2 decreased the phosphorylation of Akt2 greater than Akt1 after insulin stimulation up to 15 min. Expression of a dominant-negative DeltaIP-SHIP2 enhanced the phosphorylation of Akt2 up to 120 min. On the other hand, overexpression of WT-PTEN inhibited the phosphorylation of both Akt1 and Akt2 after short- but not long-term insulin treatment. The expression of DeltaIP-PTEN enhanced the phosphorylation of Akt1 at 120 min and that of Akt2 at 2 min. Interestingly, the expression of DeltaIP-SHIP2, but not DeltaIP-PTEN, protected against the TNF-alpha inhibition of insulin-induced phosphorylation of Akt2, GSK3, and AS160, whereas both improved the TNF-alpha inhibition of insulin-induced 2-deoxyglucose uptake. The results indicate that these lipid phosphatases possess different characteristics according to the time and preference of Akt isoform-dependent signaling in the negative regulation of the metabolic actions of insulin, whereas both inhibitions are effective in the amelioration of insulin resistance caused by TNF-alpha. PMID:19001549

Ikubo, Mariko; Wada, Tsutomu; Fukui, Kazuhito; Ishiki, Manabu; Ishihara, Hajime; Asano, Tomoichiro; Tsuneki, Hiroshi; Sasaoka, Toshiyasu

2009-01-01

86

Muscarinic M1 receptor and cannabinoid CB1 receptor do not modulate paraoxon-induced seizures  

PubMed Central

One of the major signs of severe organophosphate poisoning is seizures. Previous studies have shown that both muscarinic agonist- and organophosphate-induced seizures require activation of muscarinic acetylcholine receptors in the central nervous system. Seizures induced by the muscarinic agonist pilocarpine require the M1 receptor and are modulated by cannabinoid CB1 receptors. In this study, we determined whether M1 and CB1 receptors also regulated seizures induced by the organophosphate paraoxon. We found no differences in seizures induced by paraoxon in wild-type (WT) and M1 knockout (KO) mice, indicating that in contrast to pilocarpine seizures, M1 receptors are not required for paraoxon seizures. Furthermore, we found that pilocarpine administration resulted in seizure-independent activation of ERK in the hippocampus in a M1 receptor-dependent manner, while paraoxon did not induce seizure-independent activation of ERK in the mouse hippocampus. This shows that pilocarpine and paraoxon activated M1 receptors in the hippocampus to different extents. There were no differences in seizures induced by paraoxon in WT and CB1 KO mice, and neither CB1 agonist nor antagonist administration had significant effects on paraoxon seizures, indicating that, in contrast to pilocarpine seizures, paraoxon seizures are not modulated by CB1 receptors. These results demonstrate that there are fundamental molecular differences in the regulation of seizures induced by pilocarpine and paraoxon.

Kow, Rebecca L; Cheng, Eugene M; Jiang, Kelly; Le, Joshua H; Stella, Nephi; Nathanson, Neil M

2015-01-01

87

Elevation of global O-GlcNAc levels in 3T3-L1 adipocytes by selective inhibition of O-GlcNAcase does not induce insulin resistance.  

PubMed

The O-GlcNAc post-translational modification is considered to act as a sensor of nutrient flux through the hexosamine biosynthetic pathway. A cornerstone of this hypothesis is that global elevation of protein O-GlcNAc levels, typically induced with the non-selective O-GlcNAcase inhibitor PUGNAc (O-(2-acetamido-2-deoxy-D-glycopyranosylidene) amino-N-phenylcarbamate), causes insulin resistance in adipocytes. Here we address the potential link between elevated O-GlcNAc and insulin resistance by using a potent and selective inhibitor of O-GlcNAcase (NButGT (1,2-dideoxy-2'-propyl-alpha-D-glucopyranoso-[2,1-D]-Delta 2'-thiazoline), 1200-fold selectivity). A comparison of the structures of a bacterial homologue of O-GlcNAcase in complex with PUGNAc or NButGT reveals that these inhibitors bind to the same region of the active site, underscoring the competitive nature of their inhibition of O-GlcNAcase and the molecular basis of selectivity. Treating 3T3-L1 adipocytes with NButGT induces rapid increases in global O-GlcNAc levels, but strikingly, NButGT treatment does not replicate the insulin desensitizing effects of the non-selective O-GlcNAcase inhibitor PUGNAc. Consistent with these observations, NButGT also does not recapitulate the impaired insulin-mediated phosphorylation of Akt that is induced by treatment with PUGNAc. Collectively, these results suggest that increases in global levels of O-GlcNAc-modified proteins of cultured adipocytes do not, on their own, cause insulin resistance. PMID:18842583

Macauley, Matthew S; Bubb, Abigail K; Martinez-Fleites, Carlos; Davies, Gideon J; Vocadlo, David J

2008-12-12

88

Tension Force-Induced ATP Promotes Osteogenesis Through P2X7 Receptor in Osteoblasts  

PubMed Central

Orthodontic tooth movement induces alveolar bone resorption and formation by mechanical stimuli. Force exerted on the traction side promotes bone formation. Adenosine triphosphate (ATP) is one of the key mediators that respond to bone cells by mechanical stimuli. However, the effect of tension force (TF)-induced ATP on osteogenesis is inadequately understood. Accordingly, we investigated the effect of TF on ATP production and osteogenesis in MC3T3-E1 cells. Cells were incubated in the presence or absence of P2X7 receptor antagonist A438079, and then stimulated with or without cyclic TF (6% or 18%) for a maximum of 24?h using Flexercell Strain Unit 3000. TF significantly increased extracellular ATP release compared to control. Six percent TF had maximum effect on ATP release compared to 18% TF and control. Six percent TF induced the expression of Runx2 and Osterix. Six percent TF also increased the expression of extracellular matrix proteins (ECMPs), ALP activity, and the calcium content in ECM. A438079 blocked the stimulatory effect of 6% TF on the expression of Runx2, Osterix and ECMPs, ALP activity, and calcium content in ECM. This study indicated that TF-induced extracellular ATP is released in osteoblasts, suggesting that TF-induced ATP promotes osteogenesis by autocrine action through P2X7 receptor in osteoblasts. J. Cell. Biochem. 116: 12–21, 2015. © 2014 The Authors. Journal of Cellular Biochemistry published by Wiley Periodicals, Inc. PMID:24905552

Kariya, Taro; Tanabe, Natsuko; Shionome, Chieko; Manaka, Soichiro; Kawato, Takayuki; Zhao, Ning; Maeno, Masao; Suzuki, Naoto; Shimizu, Noriyoshi

2015-01-01

89

Tension force-induced ATP promotes osteogenesis through P2X7 receptor in osteoblasts.  

PubMed

Orthodontic tooth movement induces alveolar bone resorption and formation by mechanical stimuli. Force exerted on the traction side promotes bone formation. Adenosine triphosphate (ATP) is one of the key mediators that respond to bone cells by mechanical stimuli. However, the effect of tension force (TF)-induced ATP on osteogenesis is inadequately understood. Accordingly, we investigated the effect of TF on ATP production and osteogenesis in MC3T3-E1 cells. Cells were incubated in the presence or absence of P2X7 receptor antagonist A438079, and then stimulated with or without cyclic TF (6% or 18%) for a maximum of 24?h using Flexercell Strain Unit 3000. TF significantly increased extracellular ATP release compared to control. Six percent TF had maximum effect on ATP release compared to 18% TF and control. Six percent TF induced the expression of Runx2 and Osterix. Six percent TF also increased the expression of extracellular matrix proteins (ECMPs), ALP activity, and the calcium content in ECM. A438079 blocked the stimulatory effect of 6% TF on the expression of Runx2, Osterix and ECMPs, ALP activity, and calcium content in ECM. This study indicated that TF-induced extracellular ATP is released in osteoblasts, suggesting that TF-induced ATP promotes osteogenesis by autocrine action through P2X7 receptor in osteoblasts. PMID:24905552

Kariya, Taro; Tanabe, Natsuko; Shionome, Chieko; Manaka, Soichiro; Kawato, Takayuki; Zhao, Ning; Maeno, Masao; Suzuki, Naoto; Shimizu, Noriyoshi

2015-01-01

90

Extracellular calcium-sensing-receptor (CaR)-mediated opening of an outward K(+) channel in murine MC3T3-E1 osteoblastic cells: evidence for expression of a functional CaR  

NASA Technical Reports Server (NTRS)

The existence in osteoblasts of the G-protein-coupled extracellular calcium (Ca(o)(2+))-sensing receptor (CaR) that was originally cloned from parathyroid and kidney remains controversial. In our recent studies, we utilized multiple detection methods to demonstrate the expression of CaR transcripts and protein in several osteoblastic cell lines, including murine MC3T3-E1 cells. Although we and others have shown that high Ca(o)(2+) and other polycationic CaR agonists modulate the function of MC3T3-E1 cells, none of these actions has been unequivocally shown to be mediated by the CaR. Previous investigations using neurons and lens epithelial cells have shown that activation of the CaR stimulates Ca(2+)-activated K(+) channels. Because osteoblastic cells express a similar type of channel, we have examined the effects of specific "calcimimetic" CaR activators on the activity of a Ca(2+)-activated K(+) channel in MC3T3-E1 cells as a way of showing that the CaR is not only expressed in those cells but is functionally active. Patch-clamp analysis in the cell-attached mode showed that raising Ca(o)(2+) from 0.75 to 2.75 mmol/L elicited about a fourfold increase in the open state probability (P(o)) of an outward K(+) channel with a conductance of approximately 92 pS. The selective calcimimetic CaR activator, NPS R-467 (0.5 micromol/L), evoked a similar activation of the channel, while its less active stereoisomer, NPSS-467 (0.5 micromol/L), did not. Thus, the CaR is not only expressed in MC3T3-E1 cells, but is also functionally coupled to the activity of a Ca(2+)-activated K(+) channel. This receptor, therefore, could transduce local or systemic changes in Ca(o)(2+) into changes in the activity of this ion channel and related physiological processes in these and perhaps other osteoblastic cells.

Ye, C. P.; Yamaguchi, T.; Chattopadhyay, N.; Sanders, J. L.; Vassilev, P. M.; Brown, E. M.; O'Malley, B. W. (Principal Investigator)

2000-01-01

91

I lost weight, but I became weak and cannot walk--a case of nutraceutical (T3)-induced thyrotoxic periodic paralysis.  

PubMed

Thyrotoxic periodic paralysis (TPP) is a rare reversible cause of paralysis and cramping. TPP is usually precipitated by common causes of thyrotoxicosis such as Grave disease or multinodular goiter. TPP precipitated by exogenous triiodothyronine (T3) intake is an extremely rare occurrence with only 3 cases reported to date. We now report a 24-year-old healthy manual laborer who developed quadriparesis during a period of rest after heavy exertion and carbohydrate intake. He had severe hypokalemia (potassium level 1.9 mmole/L). Correction of his hypokalemia reversed the paralysis without rebound hyperkalemia. After a detailed history review, he reported that he had been consuming nutraceuticals containing T3 for 1 month to lose weight, and laboratory studies confirmed factitious T3 toxicosis. There was no evidence of renal or gastrointestinal potassium wasting. This episode of TPP was the first manifestation of thyrotoxicosis in this patient, and avoidance of T3 intake prevented more episodes. PMID:23567793

Panikkath, Ragesh; Nugent, Kenneth

2014-01-01

92

The effects of turmeric supplementation on antioxidant status, blood gas indices and mortality in broiler chickens with T(3)-induced ascites.  

PubMed

1. A total of 320 one-day-old Ross male broiler chickens were used to investigate the effects of 0·0, 2·5, 5·0 and 7·5 g/kg turmeric rhizome powder (TRP) in the diet, on antioxidant status, biochemical gas indices and mortality in broiler chickens with triiodothyronine (T(3)) induced ascites. 2. The TRP supplementation had no effect on blood pH, pO(2) or pCO(2) during the whole period of study. Moreover, supplementation of TRP did not influence the heart weight, right ventricle, left ventricle, or total ventricle weights, all relative to total live weight; RV/TV (right ventricle to total ventricle) ratio; or serum GPX (glutathione peroxidase) or SOD (superoxide dismutase) activities at week 6. 3. TRP supplementation influenced the blood [Formula: see text] and O(2) saturation during the whole period of study, total mortality due to ascites, and serum total tocopherol and malondialdehyde (MDA) contents. Blood [Formula: see text] and serum total tocopherol increased linearly as dietary TRP level increased. Blood O(2) saturation increased quadratically as dietary TRP increased. 4. Total ascites mortality and serum MDA content decreased linearly with increasing TRP level to 5 mg/kg and then reached a plateau. 5. The results of the study indicate that the addition of 5·0?g/kg TRP is sufficient to increase the blood O(2) saturation and bicarbonate ([Formula: see text]) concentration, and reduce the mortality due to ascites and serum MDA content. PMID:22978595

Daneshyar, M; Kermanshahi, H; Golian, A

2012-01-01

93

Implications of epidermal growth factor (EGF) induced egf receptor aggregation.  

PubMed Central

To investigate the role of receptor aggregation in EGF binding, we construct a mathematical model describing receptor dimerization (and higher levels of aggregation) that permits an analysis of the influence of receptor aggregation on ligand binding. We answer two questions: (a) Can Scatchard plots of EGF binding data be analyzed productively in terms of two noninteracting receptor populations with different affinities if EGF induced receptor aggregation occurs? No. If two affinities characterize aggregated and monomeric EGF receptors, we show that the Scatchard plot should have curvature characteristic of positively cooperative binding, the opposite of that observed. Thus, the interpretation that the high affinity population represents aggregated receptors and the low affinity population nonaggregated receptors is wrong. If the two populations are interpreted without reference to receptor aggregation, an important determinant of Scatchard plot shape is ignored. (b) Can a model for EGF receptor aggregation and EGF binding be consistent with the "negative curvature" (i.e., curvature characteristic of negatively cooperative binding) observed in most Scatchard plots of EGF binding data? Yes. In addition, the restrictions on the model parameters required to obtain negatively curved Scatchard plots provide new information about binding and aggregation. In particular, EGF binding to aggregated receptors must be negatively cooperative, i.e., binding to a receptor in a dimer (or higher oligomer) having one receptor already bound occurs with lower affinity than the initial binding event. A third question we consider is whether the model we present can be used to detect the presence of mechanisms other than receptor aggregation that are contributing to Scatchard plot curvature. For the membrane and cell binding data we analyzed, the best least squares fits of the model to each of the four data sets deviate systematically from the data, indicating that additional factors are also important in shaping the binding curves. Because we have controlled experimentally for many sources of receptor heterogeneity, we have limited the potential explanations for residual Scatchard plot curvature. Images FIGURE 4 PMID:1420877

Wofsy, C; Goldstein, B; Lund, K; Wiley, H S

1992-01-01

94

Xylazine induced central antinociception mediated by endogenous opioids and ?-opioid receptor, but not ?-or ?-opioid receptors.  

PubMed

Endogenous opioids have been implicated in compound-induced antinociception, and our group previously suggested that xylazine induces peripheral antinociception by releasing endogenous opioids that act on their respective receptors. In this study, we investigated the involvement of endogenous opioids in ?2-adrenoceptor agonist xylazine-induced central antinociception. The nociceptive threshold for thermal stimulation was measured in Swiss mice using the tail-flick test. The drugs were administered via the intracerebroventricular route. Probabilities less than 5% (p<0.05) were considered to be statistically significant (ANOVA/Bonferroni's test). Our results demonstrated that opioid receptor antagonist naloxone and ?-opioid receptor antagonist clocinnamox, but not ?-opioid receptor antagonist naltrindole and ?-opioid receptor antagonist nor-binaltorphimine, antagonized xylazine-induced central antinociception. These data provide evidence for the involvement of endogenous opioids and ?-opioid receptors in xylazine-induced central antinociception. In contrast, ?- and ?-opioid receptors do not appear to be involved in this effect. The results contribute to a greater understanding of the central antinociceptive mechanisms of a drug widely used in veterinary therapy. PMID:23485547

Romero, Thiago Roberto Lima; Pacheco, Daniela da Fonseca; Duarte, Igor Dimitri Gama

2013-04-19

95

Modulation of Pilocarpine-Induced Seizures by Cannabinoid Receptor 1  

PubMed Central

Administration of the muscarinic agonist pilocarpine is commonly used to induce seizures in rodents for the study of epilepsy. Activation of muscarinic receptors has been previously shown to increase the production of endocannabinoids in the brain. Endocannabinoids act at the cannabinoid CB1 receptors to reduce neurotransmitter release and the severity of seizures in several models of epilepsy. In this study, we determined the effect of CB1 receptor activity on the induction in mice of seizures by pilocarpine. We found that decreased activation of the CB1 receptor, either through genetic deletion of the receptor or treatment with a CB1 antagonist, increased pilocarpine seizure severity without modifying seizure-induced cell proliferation and cell death. These results indicate that endocannabinoids act at the CB1 receptor to modulate the severity of pilocarpine-induced seizures. Administration of a CB1 agonist produced characteristic CB1-dependent behavioral responses, but did not affect pilocarpine seizure severity. A possible explanation for the lack of effect of CB1 agonist administration on pilocarpine seizures, despite the effects of CB1 antagonist administration and CB1 gene deletion, is that muscarinic receptor-stimulated endocannabinoid production is acting maximally at CB1 receptors to modulate sensitivity to pilocarpine seizures. PMID:24752144

Kow, Rebecca L.; Jiang, Kelly; Naydenov, Alipi V.; Le, Joshua H.; Stella, Nephi; Nathanson, Neil M.

2014-01-01

96

Androgen-Induced Cell Migration: Role of Androgen Receptor/Filamin A Association  

PubMed Central

Background Androgen receptor (AR) controls male morphogenesis, gametogenesis and prostate growth as well as development of prostate cancer. These findings support a role for AR in cell migration and invasiveness. However, the molecular mechanism involved in AR-mediated cell migration still remains elusive. Methodology/Principal Findings Mouse embryo NIH3T3 fibroblasts and highly metastatic human fibrosarcoma HT1080 cells harbor low levels of transcriptionally incompetent AR. We now report that, through extra nuclear action, AR triggers migration of both cell types upon stimulation with physiological concentrations of the androgen R1881. We analyzed the initial events leading to androgen-induced cell migration and observed that challenging NIH3T3 cells with 10 nM R1881 rapidly induces interaction of AR with filamin A (FlnA) at cytoskeleton. AR/FlnA complex recruits integrin beta 1, thus activating its dependent cascade. Silencing of AR, FlnA and integrin beta 1 shows that this ternary complex controls focal adhesion kinase (FAK), paxillin and Rac, thereby driving cell migration. FAK-null fibroblasts migrate poorly and Rac inhibition by EHT impairs motility of androgen-treated NIH3T3 cells. Interestingly, FAK and Rac activation by androgens are independent of each other. Findings in human fibrosarcoma HT1080 cells strengthen the role of Rac in androgen signaling. The Rac inhibitor significantly impairs androgen-induced migration in these cells. A mutant AR, deleted of the sequence interacting with FlnA, fails to mediate FAK activation and paxillin tyrosine phosphorylation in androgen-stimulated cells, further reinforcing the role of AR/FlnA interaction in androgen-mediated motility. Conclusions/Significance The present report, for the first time, indicates that the extra nuclear AR/FlnA/integrin beta 1 complex is the key by which androgen activates signaling leading to cell migration. Assembly of this ternary complex may control organ development and prostate cancer metastasis. PMID:21359179

Castoria, Gabriella; D'Amato, Loredana; Ciociola, Alessandra; Giovannelli, Pia; Giraldi, Tiziana; Sepe, Leandra; Paolella, Giovanni; Barone, Maria Vittoria; Migliaccio, Antimo; Auricchio, Ferdinando

2011-01-01

97

[Inhibitory effects of shimotsu-to, a traditional Chinese herbal prescription, on ultraviolet radiation-induced cell damage and prostaglandin E2 release in cultured Swiss 3T3 cells].  

PubMed

We have investigated the effects of Shimotsu-to, a traditional Chinese herbal prescription (Kampo medicine), on ultraviolet (UV) radiation-induced cell damage and prostaglandin E2 (PGE2) release in cultured Swiss 3T3 cells to examine the anti-inflammatory mechanism of Shimotsu-to. Short-term UV irradiation significantly induced cell damage and stimulated PGE2 release in Swiss 3T3 cells cultured for 4 h. The UV-radiation-induced cell damage and the stimulation of PGE2 release were significantly suppressed by the treatment with Shimotsu-to. Among the single crude drug components of Shimotsu-to, Rehmanniae Radix showed significant protective effects against UV-radiation-induced cell damage and PGE2 release. Other synthetic anti-inflammatory agents, such as dexamethasone, dipotassium glycyrrhizinate and allantoin also protected against UV-induced cell damage and inhibited PGE2 release in cultured Swiss 3T3 cells. These results suggest that the anti-inflammatory mechanism of Shimotsu-to against UV-irradiated erythema (acute skin inflammation) in guinea pigs in vivo may be mediated by the inhibition of PGE2 release from cutaneous target cells. PMID:9629060

Sakuma, K; Ogawa, M; Kimura, M; Yamamoto, K; Ogihara, M

1998-06-01

98

Down-regulation of cellular platelet-derived growth factor receptors induced by an activated neu receptor tyrosine kinase.  

PubMed Central

The functional integration of growth factor signaling occurs at several levels in target cells. One of the most proximal mechanisms is receptor transmodulation, by which one activated receptor can regulate the expression of other receptors in the same cells. Well-established transregulatory loops involve platelet-derived growth factor (PDGF) down-regulation of epidermal growth factor (EGF) receptors and beta-type transforming growth factors modulation of PDGF receptors. We have studied the relationship between neu tyrosine kinase activation and the expression of the PDGF receptors in transfected NIH/3T3 cells. Expression of the neu oncogene, but not of the neu proto-oncogene, was associated with a decrease of PDGF alpha- and beta-receptors on the cell surface, as measured by [125-I]PDGF-AA and -BB binding. These results were corroborated by metabolic labeling and immunoprecipitation of the PDGF beta-receptors. PDGF alpha- and beta-receptor mRNAs were strongly decreased in the neu oncogene-transformed cells in comparison with control cells expressing the neu proto-oncogene. Down-regulation of the PDGF receptors and their mRNAs was also observed after EGF treatment of cells expressing a chimeric EGF receptor/neu receptor, where the neu tyrosine kinase is activated by EGF binding. These results show that the neu tyrosine kinase can down-modulate PDGF receptor expression, and the effect is mediated via decreased PDGF receptor mRNA levels. Images PMID:1685673

Lehtola, L; Nistér, M; Hölttä, E; Westermark, B; Alitalo, K

1991-01-01

99

Non-NMDA receptor antagonist-induced drinking in rat  

NASA Technical Reports Server (NTRS)

Glutamate has been implicated in the central control of mechanisms that maintain body fluid homeostasis. The present studies demonstrate that intracerebroventricular (i.c.v.) injections of the non-N-methyl-d-aspartate (NMDA) receptor antagonists 6, 7-dinitroquinoxaline-2,3-dione (DNQX) and 6-cyano-7-nitroquinoxaline-2,3 dione (CNQX) induce drinking in rats. The dipsogenic effect of i.c.v. DNQX was antagonized by the non-NMDA receptor agonist alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA). The water intake induced by DNQX was also blocked by pretreatment with a NMDA receptor antagonist, MK-801, but not by angiotensin type 1 (AT1) or acetylcholine muscarinic receptor antagonists (losartan and atropine). The results indicate that non-NMDA receptors may exert a tonic inhibitory effect within brain circuits that control dipsogenic activity and that functional integrity of NMDA receptors may be required for the non-NMDA receptor antagonists to induce water intake. Copyright 1998 Published by Elsevier Science B.V.

Xu, Z.; Johnson, A. K.

1998-01-01

100

Insulin-Mimetic Action of Rhoifolin and Cosmosiin Isolated from Citrus grandis (L.) Osbeck Leaves: Enhanced Adiponectin Secretion and Insulin Receptor Phosphorylation in 3T3-L1 Cells  

PubMed Central

Citrus grandis (L.) Osbeck (red wendun) leaves have been used in traditional Chinese medicine to treat several illnesses including diabetes. However, there is no scientific evidence supporting these actions and its active compounds. Two flavone glycosides, rhoifolin and cosmosiin were isolated for the first time from red wendun leaves and, identified these leaves are rich source for rhoifolin (1.1%, w/w). In differentiated 3T3-L1 adipocytes, rhoifolin and cosmosiin showed dose-dependent response in concentration range of o.oo1–5??M and 1–20??M, respectively, in biological studies beneficial to diabetes. Particularly, rhoifolin and cosmosiin at 0.5 and 20??M, respectively showed nearly similar response to that 10?nM of insulin, on adiponectin secretion level. Furthermore, 5??M of rhoifolin and 20??M of cosmosiin showed equal potential with 10?nM of insulin to increase the phosphorylation of insulin receptor-?, in addition to their positive effect on GLUT4 translocation. These findings indicate that rhoifolin and cosmosiin from red wendun leaves may be beneficial for diabetic complications through their enhanced adiponectin secretion, tyrosine phosphorylation of insulin receptor-? and GLUT4 translocation. PMID:20008903

Rao, Yerra Koteswara; Lee, Meng-Jen; Chen, Keru; Lee, Yi-Ching; Wu, Wen-Shi; Tzeng, Yew-Min

2011-01-01

101

NIH3T3 cells overexpressing CD98 heavy chain resist early G1 arrest and apoptosis induced by serum starvation.  

PubMed

CD98 is a heterodimeric glycoprotein of 125-kDa, which consists of a 90-kDa heavy chain (hc) subunit and 35-kDa to 55-kDa light chain (lc) subunits. It is strongly expressed on the surface of proliferating normal cells and almost all tumor cells. To investigate the participation of CD98 in cellular proliferation and malignant transformation, we analyzed cell-cycle progression of NIH3T3 clones transfected with cDNA of human CD98hc. Although NIH3T3 and control transfectant cells grown to the subconfluent state were arrested in the G0/G1 phase by serum starvation, considerable portions of CD98hc-transfected cells resided at S and G2/M phases. Under serum-starved and confluent conditions, significant fractions (20-25%) of NIH3T3 and control transfectant cells contained less than 2n content DNA, indicating occurrence of apoptosis, whereas no apoptotic cells were detected in CD98hc-transfectant cells. Under serum-starved conditions, a marked increase in the levels of cyclin D1 and cyclin E and a decrease in p16 were observed in CD98hc-transfectant cells. The reverse was true for NIH3T3 and control transfectant cells. Our results suggest that resistance to G1 arrest and apoptosis by CD98 overexpression are associated with high G1-cyclins and low p16 levels. PMID:22497681

Hara, Kaori; Ueda, Shiho; Ohno, Yoshiya; Tanaka, Toshiyuki; Yagi, Hideki; Okazaki, Shogo; Kawahara, Rieko; Masayuki, Takechi; Enomoto, Takemi; Hashimoto, Yoshiyuki; Masuko, Kazue; Masuko, Takashi

2012-08-01

102

Psychostimulant-Induced Neuroadaptations in Nucleus Accumbens AMPA Receptor Transmission  

PubMed Central

Medium spiny neurons of the nucleus accumbens serve as the interface between corticolimbic regions that elicit and modulate motivated behaviors, including those related to drugs of abuse, and motor regions responsible for their execution. Medium spiny neurons are excited primarily by AMPA-type glutamate receptors, making AMPA receptor transmission in the accumbens a key regulatory point for addictive behaviors. In animal models of cocaine addiction, changes in the strength of AMPA receptor transmission onto accumbens medium spiny neurons have been shown to underlie cocaine-induced behavioral adaptations related to cocaine seeking. Here we review changes in AMPA receptor levels and subunit composition that occur after discontinuing different types of cocaine exposure, as well as changes elicited by cocaine reexposure following abstinence or extinction. Signaling pathways that regulate these cocaine-induced adaptations will also be considered, as they represent potential targets for addiction pharmacotherapies. PMID:23232118

Pierce, R. Christopher; Wolf, Marina E.

2013-01-01

103

Anandamide induces overeating: mediation by central cannabinoid (CB1) receptors  

Microsoft Academic Search

Rationale: Central cannabinoid systems have been implicated in appetite regulation by the respective hyperphagic actions of exogenous\\u000a cannabinoids, such as ?9-THC, and hypophagic effects of selective cannabinoid receptor antagonists. Objective: This study examined whether an endogenous cannabinoid, anandamide, could induce overeating, via a specific action at central\\u000a (CB1) cannabinoid receptors. Methods: Pre-satiated male rats (n=18), received subcutaneous injections of anandamide

Claire M. Williams; Tim C. Kirkham

1999-01-01

104

Type III Secretion Needle Proteins Induce Cell Signaling and Cytokine Secretion via Toll-Like Receptors  

PubMed Central

Pathogens are recognized by hosts by use of various receptors, including the Toll-like receptor (TLR) and Nod-like receptor (NLR) families. Ligands for these varied receptors, including bacterial products, are identified by the immune system, resulting in development of innate immune responses. Only a couple of components from type III secretion (T3S) systems are known to be recognized by TLR or NLR family members. Known T3S components that are detected by pattern recognition receptors (PRRs) are (i) flagellin, detected by TLR5 and NLRC4 (Ipaf); and (ii) T3S rod proteins (PrgJ and homologs) and needle proteins (PrgI and homologs), detected by NAIP and the NLRC4 inflammasome. In this report, we characterize the induction of proinflammatory responses through TLRs by the Yersinia pestis T3S needle protein, YscF, the Salmonella enterica needle proteins PrgI and SsaG, and the Shigella needle protein, MxiH. More specifically, we determine that the proinflammatory responses occur through TLR2 and -4. These data support the hypothesis that T3S needles have an unrecognized role in bacterial pathogenesis by modulating immune responses. PMID:24643544

Jessen, Danielle L.; Osei-Owusu, Patrick; Toosky, Melody; Roughead, William; Bradley, David S.

2014-01-01

105

Type III secretion needle proteins induce cell signaling and cytokine secretion via Toll-like receptors.  

PubMed

Pathogens are recognized by hosts by use of various receptors, including the Toll-like receptor (TLR) and Nod-like receptor (NLR) families. Ligands for these varied receptors, including bacterial products, are identified by the immune system, resulting in development of innate immune responses. Only a couple of components from type III secretion (T3S) systems are known to be recognized by TLR or NLR family members. Known T3S components that are detected by pattern recognition receptors (PRRs) are (i) flagellin, detected by TLR5 and NLRC4 (Ipaf); and (ii) T3S rod proteins (PrgJ and homologs) and needle proteins (PrgI and homologs), detected by NAIP and the NLRC4 inflammasome. In this report, we characterize the induction of proinflammatory responses through TLRs by the Yersinia pestis T3S needle protein, YscF, the Salmonella enterica needle proteins PrgI and SsaG, and the Shigella needle protein, MxiH. More specifically, we determine that the proinflammatory responses occur through TLR2 and -4. These data support the hypothesis that T3S needles have an unrecognized role in bacterial pathogenesis by modulating immune responses. PMID:24643544

Jessen, Danielle L; Osei-Owusu, Patrick; Toosky, Melody; Roughead, William; Bradley, David S; Nilles, Matthew L

2014-06-01

106

Hypoxia-Induced Silencing of NMDA Receptors in Turtle Neurons  

Microsoft Academic Search

Hypoxia-induced suppression of NMDA receptors (NMDARs) in western painted turtle (Chrysemys picta) cortical neurons may be critical for surviving months of anoxic dormancy. We report that NMDARs are silenced by at least three different mecha- nisms operating at different times during anoxia. In pyramidal neurons from cerebrocortex, 1-8 min anoxia suppressed NMDAR activity (Ca 21 influx and open probability) by

Philip E. Bickler; Paul H. Donohoe; Leslie T. Buck

2000-01-01

107

GABA-induced uncoupling of GABA/benzodiazepine site interactions is mediated by increased GABAA receptor internalization and associated with a change in subunit composition.  

PubMed

Persistent activation of GABAA receptors triggers compensatory changes in receptor function that are relevant to physiological, pathological and pharmacological conditions. Chronic treatment of cultured neurons with GABA for 48h has been shown to produce a down-regulation of receptor number and an uncoupling of GABA/benzodiazepine site interactions with a half-time of 24-25h. Down-regulation is the result of a transcriptional repression of GABAA receptor subunit genes and depends on activation of L-type voltage-gated calcium channels. The mechanism of this uncoupling is currently unknown. We have previously demonstrated that a single brief exposure of rat primary neocortical cultures to GABA for 5-10min (t½=3min) initiates a process that results in uncoupling hours later (t½=12h) without a change in receptor number. Uncoupling is contingent upon GABAA receptor activation and independent of voltage-gated calcium influx. This process is accompanied by a selective decrease in subunit mRNA levels. Here, we report that the brief GABA exposure induces a decrease in the percentage of ?3-containing receptors, a receptor subtype that exhibits a high degree of coupling between GABA and benzodiazepine binding sites. Initiation of GABA-induced uncoupling is prevented by co-incubation of GABA with high concentrations of sucrose suggesting that it is dependent on a receptor internalization step. Moreover, results from immunocytochemical and biochemical experiments indicate that GABA exposure causes an increase in GABAA receptor endocytosis. Together, these data suggest that the uncoupling mechanism involves an initial increase in receptor internalization followed by activation of a signaling cascade that leads to selective changes in receptor subunit levels. These changes might result in the assembly of receptors with altered subunit compositions that display a lower degree of coupling between GABA and benzodiazepine sites. Uncoupling might represent a homeostatic mechanism that negatively regulates GABAergic transmission under physiological conditions in which synaptic GABAA receptors are transiently activated for several minutes. PMID:24215979

Gutiérrez, M L; Ferreri, M C; Gravielle, M C

2014-01-17

108

Dissociation of bradykinin-induced prostaglandin formation from phosphatidylinositol turnover in Swiss 3T3 fibroblasts: evidence for G protein regulation of phospholipase Aâ  

Microsoft Academic Search

In Swiss 3T3 fibroblasts bradykinin stimulated inositol phosphate (InsP) formation and prostaglandin Eâ (PGEâ) synthesis. The ECââ values for stimulation of PGEâ synthesis and InsP formation by bradykinin were similar, 200 pM and 275 pM, respectively. Guanosine-5'-(..gamma..-thio)triphosphate stimulated PGEâ synthesis and InsP formation, and guanosine-5'-(..beta..-thio)diphosphate inhibited both PGEâ synthesis and InsP formation stimulated by bradykinin. Neither bradykinin-stimulated PGEâ synthesis nor

R. M. Burch; J. Axelrod

1987-01-01

109

Molecular mechanism of 9-cis-retinoic acid inhibition of adipogenesis in 3T3-L1 cells  

SciTech Connect

Highlights: ? We examined the effects of 9-cis-RA on adipogenesis in mouse preadipocyte 3T3-L1. ? 9-cis-RA inhibited lipid accumulation in adipogenetically-induced 3T3-L1 cells. ? A RXR pan-antagonist suppressed the inhibitory effects of 9-cis-RA on adipogenesis. ? This antagonist had no effects on RXR? and PPAR? levels in 9-cis-RA-treated cells. ? 9-cis-RA-induced decrease in both RXR? and PPAR? was independent of RXR activation. -- Abstract: Retinoic acid (RA) signaling is mediated by specific nuclear hormone receptors. Here we examined the effects of 9-cis-RA on adipogenesis in mouse preadipocyte 3T3-L1 cells. 9-cis-RA inhibits the lipid accumulation of adipogenetically induced 3T3-L1 cells. The complex of retinoid X receptor ? (RXR?) with peroxisome proliferator-activated receptor ? (PPAR?) is a major transcription factor in the process of adipogenesis, and the levels of these molecules were decreased by 9-cis-RA treatment. A RXR pan-antagonist suppressed 9-cis-RA’s inhibitory effects on adipogenesis, but not on the intracellular levels of both RXR? and PPAR?. These results suggest that 9-cis-RA could inhibit adipogenesis by activating RXR, and decrease both RXR and PPAR?s levels in a RXR activation-independent manner.

Sagara, Chiaki; Takahashi, Katsuhiko [Laboratory of Physiological Chemistry, Institute of Medicinal Chemistry, Hoshi University, Shinagawa, Tokyo 142-8501 (Japan)] [Laboratory of Physiological Chemistry, Institute of Medicinal Chemistry, Hoshi University, Shinagawa, Tokyo 142-8501 (Japan); Kagechika, Hiroyuki [School of Biomedical Science, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, Chiyoda, Tokyo 101-0062 (Japan)] [School of Biomedical Science, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, Chiyoda, Tokyo 101-0062 (Japan); Takahashi, Noriko, E-mail: t-noriko@hoshi.ac.jp [Laboratory of Physiological Chemistry, Institute of Medicinal Chemistry, Hoshi University, Shinagawa, Tokyo 142-8501 (Japan)] [Laboratory of Physiological Chemistry, Institute of Medicinal Chemistry, Hoshi University, Shinagawa, Tokyo 142-8501 (Japan)

2013-03-29

110

Mediator subunit MED1 is a T3-dependent and T3-independent coactivator on the thyrotropin ? gene promoter  

SciTech Connect

Highlights: •MED1 is a bona fide T3-dependent coactivator on TSHB promoter. •Mice with LxxLL-mutant MED1 have attenuated TSH? mRNA and thyroid hormone levels. •MED1 activates TSHB promoter T3-dependently in cultured cells. •T3-dependent MED1 action is enhanced when SRC1/SRC2 or HDAC2 is downregulated. •MED1 is also a T3-independent GATA2/Pit1 coactivator on TSHB promoter. -- Abstract: The MED1 subunit of the Mediator transcriptional coregulator complex is a nuclear receptor-specific coactivator. A negative feedback mechanism of thyroid-stimulating hormone (TSH, or thyrotropin) expression in the thyrotroph in the presence of triiodothyronine (T3) is employed by liganded thyroid hormone receptor ? (TR?) on the TSH? gene promoter, where conventional histone-modifying coactivators act as corepressors. We now provide evidence that MED1 is a ligand-dependent positive cofactor on this promoter. TSH? gene transcription was attenuated in MED1 mutant mice in which the nuclear receptor-binding ability of MED1 was specifically disrupted. MED1 stimulated GATA2- and Pit1-mediated TSH? gene promoter activity in a ligand-independent manner in cultured cells. MED1 also stimulated transcription from the TSH? gene promoter in a T3-dependent manner. The transcription was further enhanced when the T3-dependent corepressors SRC1, SRC2, and HDAC2 were downregulated. Hence, MED1 is a T3-dependent and -independent coactivator on the TSH? gene promoter.

Matsui, Keiji; Oda, Kasumi; Mizuta, Shumpei; Ishino, Ruri; Urahama, Norinaga; Hasegawa, Natsumi [Laboratory of Hematology, Division of Medical Biophysics, Kobe University Graduate School of Health Sciences, 7-10-2 Tomogaoka, Suma-ku, Kobe 654-0142 (Japan)] [Laboratory of Hematology, Division of Medical Biophysics, Kobe University Graduate School of Health Sciences, 7-10-2 Tomogaoka, Suma-ku, Kobe 654-0142 (Japan); Roeder, Robert G. [Laboratory of Biochemistry and Molecular Biology, The Rockefeller University, 1230 York Avenue, New York, NY 10065 (United States)] [Laboratory of Biochemistry and Molecular Biology, The Rockefeller University, 1230 York Avenue, New York, NY 10065 (United States); Ito, Mitsuhiro, E-mail: itomi@med.kobe-u.ac.jp [Laboratory of Hematology, Division of Medical Biophysics, Kobe University Graduate School of Health Sciences, 7-10-2 Tomogaoka, Suma-ku, Kobe 654-0142 (Japan) [Laboratory of Hematology, Division of Medical Biophysics, Kobe University Graduate School of Health Sciences, 7-10-2 Tomogaoka, Suma-ku, Kobe 654-0142 (Japan); Laboratory of Biochemistry and Molecular Biology, The Rockefeller University, 1230 York Avenue, New York, NY 10065 (United States); Department of Family and Community Medicine, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe 654-0142 (Japan); Consolidated Research Institute for Advanced Science and Medical Care, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 159-8555 (Japan)

2013-10-11

111

G protein-coupled receptor-induced sensitization of phospholipase C stimulation by receptor tyrosine kinases.  

PubMed

Activation of stably expressed M(2) and M(3) muscarinic acetylcholine receptors (mAChRs) as well as of endogenously expressed lysophosphatidic acid and purinergic receptors in HEK-293 cells can induce a long lasting potentiation of phospholipase C (PLC) stimulation by these and other G protein-coupled receptors (GPCRs). Here, we report that GPCRs can induce an up-regulation of PLC stimulation by receptor tyrosine kinases (RTKs) as well and provide essential mechanistic characteristics of this sensitization process. Pretreatment of HEK-293 cells for 2 min with carbachol, a mAChR agonist, lysophosphatidic acid, or ATP, followed by agonist washout, strongly increased (by 2-3-fold) maximal PLC stimulation (measured >/=40 min later) by epidermal growth factor and platelet-derived growth factor, but not insulin, and largely enhanced PLC sensitivity to these RTK agonists. The up-regulation of RTK-induced PLC stimulation was cycloheximide-insensitive and was observed for up to approximately 90 min after removal of the GPCR agonist. Sensitization of receptor-induced PLC stimulation caused by prior M(2) mAChR activation was fully prevented by pertussis toxin and strongly reduced by expression of Gbetagamma scavengers. Furthermore, inhibition of conventional protein kinase C (PKC) isoenzymes and chelation of intracellular Ca(2+) suppressed the sensitization process, while overexpression of PKC-alpha, but not PKC-betaI, further enhanced the M(2) mAChR-induced sensitization of PLC stimulation. None of these treatments affected acute PLC stimulation by either GPCR or RTK agonists. Taken together, short term activation of GPCRs can induce a strong and long lasting sensitization of PLC stimulation by RTKs, a process apparently involving G(i)-derived Gbetagammas as well as increases in intracellular Ca(2+) and activation of a PKC isoenzyme, most likely PKC-alpha. PMID:10908568

Schmidt, M; Frings, M; Mono, M L; Guo, Y; Weernink, P A; Evellin, S; Han, L; Jakobs, K H

2000-10-20

112

Protective effects of glycyrrhizin against ??-adrenergic receptor agonist-induced receptor internalization and cell apoptosis.  

PubMed

It has been reported that treatment with ?? adrenergic receptor (??AR) agonist bronchodilators may result in airway ??ARs internalization and cardiac muscle cells apoptosis. This could lead to the loss of pharmacological effect of ??AR agonists and increase adverse cardiovascular events in asthma patients receiving ??AR agonist therapy. Glycyrrhizin, the major bioactive component of licorice root extract, has been reported to exhibit protective effect on respiratory system. Here, we investigate the effects of glycyrrhizin against ??AR agonist salbutamol-induced receptor internalization and cell apoptosis. In our study, the live cell confocal imaging and fixed-cell enzyme-linked immunosorbent assay (ELISA) assay revealed that glycyrrhizin significantly inhibited salbutamol-induced surface ??AR internalization. The underlying mechanisms were then identified to be that glycyrrhizin could reduce the association of ??ARs with ?-arrestins and clathrin heavy chain as well as the level of G protein-coupled receptor kinase (GRK) mediated phosphorylation of ??ARs. The inhibition of receptor internalization by glycyrrhizin further lead to stabilization of the ??AR mRNA and protein expression, thus amplified the transmembrane signaling via the ??ARs. We also proved that glycyrrhizin could profoundly attenuate salbutamol-induced early cellular apoptosis by regulating the expressions of B-cell lymphoma 2 (Bcl-2) family genes. Taken together, our results suggest that glycyrrhizin exhibits protective effects against ??AR agonist-induced receptor internalization and cell apoptosis. These findings might have practical implications for future strategies of combined application of glycyrrhizin with ??AR receptor agonists to improve the efficacy of bronchodilators in patients with asthma and chronic obstructive pulmonary disease (COPD). PMID:21532146

Shi, Qian; Hou, Yuanyuan; Yang, Yang; Bai, Gang

2011-01-01

113

HOMOLOGOUS UP-REGULATION OF THE GONADOTROPIN-RELEASING HORMONE RECEPTOR IN A T3-1 CELLS IS ASSOCIATED WITH UNCHANGED RECEPTOR MESSENGER RNA (MRNA) LEVELS AND ALTERED MRNA ACTIVITY  

EPA Science Inventory

Depending on the concentration and duration of agonist exposure, gonadotropin-releasing hormone (GnRH) receptor number either increases or decreases in response to GnRH. he molecular basis of this regulation could involve a combination of modulation of gene transcription, RNA pro...

114

Endoplasmic reticulum stress suppresses lipin-1 expression in 3T3-L1 adipocytes  

SciTech Connect

Highlights: ? Lipin-1 involves lipid metabolism, adipocyte differentiation, and inflammation. ? Adipose lipin-1 expression is reduced in obesity. ? ER stress suppresses lipin-1 expression in 3T3-L1 adipocytes. ? Activation of PPAR-? recovers ER stress-induced lipin-1 reduction. -- Abstract: Lipin-1 plays crucial roles in the regulation of lipid metabolism and cell differentiation in adipocytes. In obesity, adipose lipin-1 mRNA expression is decreased and positively correlated with systemic insulin sensitivity. Amelioration of the lipin-1 depletion might be improved dysmetabolism. Although some cytokines such as TNF-? and interleukin-1? reduces adipose lipin-1 expression, the mechanism of decreased adipose lipin-1 expression in obesity remains unclear. Recently, endoplasmic reticulum (ER) stress is implicated in the pathogenesis of obesity. Here we investigated the role of ER stress on the lipin-1 expression in 3T3-L1 adipocytes. We demonstrated that lipin-1 expression was suppressed by the treatment with ER stress inducers (tunicamycin and thapsigargin) at transcriptional level. We also showed that constitutive lipin-1 expression could be maintained by peroxisome proliferator-activated receptor-? in 3T3-L1 adipocytes. Activation of peroxisome proliferator-activated receptor-? recovered the ER stress-induced lipin-1 suppression. These results suggested that ER stress might be involved in the pathogenesis of obesity through lipin-1 depletion.

Takahashi, Nobuhiko, E-mail: ntkhs@hoku-iryo-u.ac.jp [Department of Internal Medicine, School of Dentistry, Health Sciences University of Hokkaido, 1757, Kanazawa, Ishikari-Toubetsu, Hokkaido 061-0023 (Japan) [Department of Internal Medicine, School of Dentistry, Health Sciences University of Hokkaido, 1757, Kanazawa, Ishikari-Toubetsu, Hokkaido 061-0023 (Japan); Division of Gastroenterology and Hematology/Oncology, Department of Medicine, Asahikawa Medical University, 2-1-1-1, Midorigaoka-Higashi, Asahikawa, Hokkaido 078-8510 (Japan); Yoshizaki, Takayuki [Innovation Center, Kagoshima University, 1-21-40, Korimoto, Kagoshima 890-0065 (Japan)] [Innovation Center, Kagoshima University, 1-21-40, Korimoto, Kagoshima 890-0065 (Japan); Hiranaka, Natsumi; Suzuki, Takeshi [Department of Internal Medicine, School of Dentistry, Health Sciences University of Hokkaido, 1757, Kanazawa, Ishikari-Toubetsu, Hokkaido 061-0023 (Japan)] [Department of Internal Medicine, School of Dentistry, Health Sciences University of Hokkaido, 1757, Kanazawa, Ishikari-Toubetsu, Hokkaido 061-0023 (Japan); Yui, Tomoo; Akanuma, Masayoshi [Department of Fixed Prosthodontics and Oral Implantology, School of Dentistry, Health Sciences University of Hokkaido, 1757, Kanazawa, Ishikari-Toubetsu, Hokkaido 061-0023 (Japan)] [Department of Fixed Prosthodontics and Oral Implantology, School of Dentistry, Health Sciences University of Hokkaido, 1757, Kanazawa, Ishikari-Toubetsu, Hokkaido 061-0023 (Japan); Kanazawa, Kaoru [Department of Dental Anesthesiology, School of Dentistry, Health Sciences University of Hokkaido, 1757, Kanazawa, Ishikari-Toubetsu, Hokkaido 061-0023 (Japan)] [Department of Dental Anesthesiology, School of Dentistry, Health Sciences University of Hokkaido, 1757, Kanazawa, Ishikari-Toubetsu, Hokkaido 061-0023 (Japan); Yoshida, Mika; Naito, Sumiyoshi [Department of Clinical Laboratory, Health Sciences University of Hokkaido, 1757, Kanazawa, Ishikari-Toubetsu, Hokkaido 061-0023 (Japan)] [Department of Clinical Laboratory, Health Sciences University of Hokkaido, 1757, Kanazawa, Ishikari-Toubetsu, Hokkaido 061-0023 (Japan); Fujiya, Mikihiro; Kohgo, Yutaka [Division of Gastroenterology and Hematology/Oncology, Department of Medicine, Asahikawa Medical University, 2-1-1-1, Midorigaoka-Higashi, Asahikawa, Hokkaido 078-8510 (Japan)] [Division of Gastroenterology and Hematology/Oncology, Department of Medicine, Asahikawa Medical University, 2-1-1-1, Midorigaoka-Higashi, Asahikawa, Hokkaido 078-8510 (Japan); Ieko, Masahiro [Department of Internal Medicine, School of Dentistry, Health Sciences University of Hokkaido, 1757, Kanazawa, Ishikari-Toubetsu, Hokkaido 061-0023 (Japan)] [Department of Internal Medicine, School of Dentistry, Health Sciences University of Hokkaido, 1757, Kanazawa, Ishikari-Toubetsu, Hokkaido 061-0023 (Japan)

2013-02-01

115

Vitamin K induces osteoblast differentiation through pregnane X receptor-mediated transcriptional control of the Msx2 gene.  

PubMed

Vitamin K is a fat-soluble vitamin that serves as a coenzyme for vitamin K-dependent carboxylase. Besides its canonical action, vitamin K binds to the steroid and xenobiotic receptor (SXR)/pregnane X receptor (PXR) and modulates gene transcription. To determine if the osteoprotective action of vitamin K is the result of the PXR/SXR pathway, we screened by two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis the PXR/SXR target genes in an osteoblastic cell line (MC3T3-E1) treated with a vitamin K2 (menaquinone 4 [MK4]). Osteoblastic differentiation of MC3T3-E1 cells was induced by MK4. Msx2, an osteoblastogenic transcription factor, was identified as an MK4-induced gene. Functional analysis of the Msx2 gene promoter mapped a vitamin K-responsive element (PXR-responsive element [PXRE]) that was directly bound by a PXR/retinoid X receptor alpha heterodimer. In a chromatin immunoprecipitation analysis, PXR was recruited together with a coactivator, p300, to the PXRE in the Msx2 promoter. MK4-bound PXR cooperated with estrogen-bound estrogen receptor alpha to control transcription at the Msx2 promoter. Knockdown of either PXR or Msx2 attenuated the effect of MK4 on osteoblastic differentiation. Thus, the present study suggests that Msx2 is a target gene for PXR activated by vitamin K and suggests that the osteoprotective action of MK4 in the human mediates, at least in part, a genomic pathway of vitamin K signaling. PMID:17875939

Igarashi, Mamoru; Yogiashi, Yoshiko; Mihara, Masatomo; Takada, Ichiro; Kitagawa, Hirochika; Kato, Shigeaki

2007-11-01

116

Opioid receptor blockade reduces Fas-induced hepatitis in mice.  

PubMed

Fas (CD95)-induced hepatocyte apoptosis and cytotoxic activity of neutrophils infiltrating the injured liver are two major events leading to hepatitis. Because it has been reported that opioids, via a direct interaction, sensitize splenocytes to Fas-mediated apoptosis by upregulating Fas messenger RNA (mRNA) and modulated neutrophil activity, we assumed that opioids may participate in the pathophysiology of hepatitis. Using the hepatitis model induced by agonistic anti-Fas antibody in mice, we showed that opioid receptor blockade reduced liver damage and consequently increased the survival rate of animals when the antagonist naltrexone was injected simultaneously or prior to antibody administration. Treatment of mice with morphine enhanced mortality. Naloxone methiodide-a selective peripheral opioid antagonist-had a protective effect, but the absence of opioid receptors in the liver, together with lack of morphine effect in Fas-induced apoptosis of primary cultured hepatocytes, ruled out a direct effect of opioids on hepatocytes. In addition, the neutralization of opioid activity by naltrexone did not modify Fas mRNA expression in the liver as assessed with real-time quantitative polymerase chain reaction. Injured livers were infiltrated by neutrophils, but granulocyte-depleted mice were not protected against the enhancing apoptotic effect of morphine. In conclusion, opioid receptor blockade improves the resistance of mice to Fas-induced hepatitis via a peripheral mechanism that does not involve a down-modulation of Fas mRNA in hepatocytes nor a decrease in proinflammatory activity of neutrophils. PMID:15389866

Jaume, Martial; Jacquet, Sébastien; Cavaillès, Pierre; Macé, Gaëtane; Stephan, Lionel; Blanpied, Catherine; Demur, Cécile; Brousset, Pierre; Dietrich, Gilles

2004-11-01

117

A primer on cytokines: sources, receptors, effects, and inducers.  

PubMed Central

Protection against pathogens is a prerequisite for survival of most organisms. To cope with this continuous challenge, complex defense mechanisms have evolved. The construction, adaptation, and maintenance of these mechanisms are under control of an extensive network of regulatory proteins called cytokines. A great number of cytokines have been described over the last 2 decades. This review consists of an overview of cytokines that are involved in immune responses and describes some historical and general aspects as well as prospective clinical applications. Major biological effects together with information on cytokine receptors, producers, inducers, and biochemical and molecular characteristics are listed in tables. In addition, some basic information is given on cytokine receptor signal transduction. Finally, the recent discoveries of cytokine receptors functioning as coreceptors in the pathogenesis of human immunodeficiency virus are summarized. PMID:9336671

Curfs, J H; Meis, J F; Hoogkamp-Korstanje, J A

1997-01-01

118

Dark chocolate receptors: epicatechin-induced cardiac protection is dependent on ?-opioid receptor stimulation  

PubMed Central

Epicatechin, a flavonoid, is a well-known antioxidant linked to a variety of protective effects in both humans and animals. In particular, its role in protection against cardiovascular disease has been demonstrated by epidemiologic studies. Low-dose epicatechin, which does not have significant antioxidant activity, is also protective; however, the mechanism by which low-dose epicatechin induces this effect is unknown. Our laboratory tested the hypothesis that low-dose epicatechin mediates cardiac protection via opioid receptor activation. C57BL/6 mice were randomly assigned to 1 of 10 groups: control, epicatechin, naloxone (nonselective opioid receptor antagonist), epicatechin + naloxone, naltrindole (?-specific opioid receptor antagonist), epicatechin + naltrindole, norbinaltorphimine (nor-BNI, ?-specific opioid receptor antagonist), epicatechin + nor-BNI, 5-hydroxydecanoic acid [5-HD, ATP-sensitive potassium channel antagonist], and epicatechin + 5-HD. Epicatechin (1 mg/kg) or other inhibitors (5 mg/kg) were administered by oral gavage or intraperitoneal injection, respectively, daily for 10 days. Mice were subjected to 30 min coronary artery occlusion followed by 2 h of reperfusion, and infarct size was determined via planimetry. Whole heart homogenates were assayed for downstream opioid receptor signaling targets. Infarct size was significantly reduced in epicatechin- and epicatechin + nor-BNI-treated mice compared with control mice. This protection was blocked by naloxone, naltrindole, and 5-HD. Epicatechin and epicatechin + nor-BNI increased the phosphorylation of Src, Akt, and I?B?, while simultaneously decreasing the expression of c-Jun NH2-terminal kinase and caspase-activated DNase. All signaling effects are consistent with opioid receptor stimulation and subsequent cardiac protection. Naloxone, naltrindole, and 5-HD attenuated these effects. In conclusion, epicatechin acts via opioid receptors and more specifically through the ?-opioid receptor to produce cardiac protection from ischemia-reperfusion injury. PMID:20833967

Panneerselvam, Mathivadhani; Tsutsumi, Yasuo M.; Bonds, Jacqueline A.; Horikawa, Yousuke T.; Saldana, Michelle; Dalton, Nancy D.; Head, Brian P.; Patel, Piyush M.; Roth, David M.

2010-01-01

119

Hyaluronic Acid Induces Activation of the ?-Opioid Receptor  

PubMed Central

Introduction Nociceptive pain is one of the most common types of pain that originates from an injury involving nociceptors. Approximately 60% of the knee joint innervations are classified as nociceptive. The specific biological mechanism underlying the regulation of nociceptors is relevant for the treatment of symptoms affecting the knee joint. Intra-articular administration of exogenous hyaluronic acid (HA) in patients with osteoarthritis (OA) appears to be particularly effective in reducing pain and improving patient function. Methods We performed an in vitro study conducted in CHO cells that expressed a panel of opioid receptors and in primary rat dorsal root ganglion (DRG) neurons to determine if HA induces the activation of opioid peptide receptors (OPr) using both aequorin and the fluorescent dye Fura-2/AM. Results Selective agonists and antagonists for each OPr expressed on CHO cells were used to test the efficacy of our in vitro model followed by stimulation with HA. The results showed that HA induces stimulatory effects on the ? receptor (KOP). These effects of HA were also confirmed in rat DRG neurons, which express endogenously the OPr. Conclusions HA activates the KOP receptor in a concentration dependent manner, with a pEC50 value of 7.57. PMID:23383210

Zavan, Barbara; Ferroni, Letizia; Giorgi, Carlotta; Calò, Girolamo; Brun, Paola; Cortivo, Roberta; Abatangelo, Giovanni; Pinton, Paolo

2013-01-01

120

Prostaglandin E2-induced inflammation: Relevance of prostaglandin E receptors.  

PubMed

Prostaglandin E2 (PGE2) is one of the most typical lipid mediators produced from arachidonic acid (AA) by cyclooxygenase (COX) as the rate-limiting enzyme, and acts on four kinds of receptor subtypes (EP1-EP4) to elicit its diverse actions including pyrexia, pain sensation, and inflammation. Recently, the molecular mechanisms underlying the PGE2 actions mediated by each EP subtype have been elucidated by studies using mice deficient in each EP subtype as well as several compounds highly selective to each EP subtype, and their findings now enable us to discuss how PGE2 initiates and exacerbates inflammation at the molecular level. Here, we review the recent advances in PGE2 receptor research by focusing on the activation of mast cells via the EP3 receptor and the control of helper T cells via the EP2/4 receptor, which are the molecular mechanisms involved in PGE2-induced inflammation that had been unknown for many years. We also discuss the roles of PGE2 in acute inflammation and inflammatory disorders, and the usefulness of anti-inflammatory therapies that target EP receptors. This article is part of a Special Issue entitled "Oxygenated metabolism of PUFA: Analysis and biological relevance". PMID:25038274

Kawahara, Kohichi; Hohjoh, Hirofumi; Inazumi, Tomoaki; Tsuchiya, Soken; Sugimoto, Yukihiko

2014-07-17

121

Ascofuranone stimulates expression of adiponectin and peroxisome proliferator activated receptor through the modulation of mitogen activated protein kinase family members in 3T3-L1, murine pre-adipocyte cell line  

SciTech Connect

Highlights: Black-Right-Pointing-Pointer Ascofuranone increases expression of adiponectin and PPAR{gamma}. Black-Right-Pointing-Pointer Inhibitors for MEK and JNK increased the expression of adiponectin and PPAR{gamma}. Black-Right-Pointing-Pointer Ascofuranone significantly suppressed phosho-ERK, while increasing phospho-p38. -- Abstract: Ascofuranone, an isoprenoid antibiotic, was originally isolated as a hypolipidemic substance from a culture broth of the phytopathogenic fungus, Ascochyta visiae. Adiponectin is mainly synthesized by adipocytes. It relieves insulin resistance by decreasing the plasma triglycerides and improving glucose uptake, and has anti-atherogenic properties. Here, we found that ascofuranone increases expression of adiponectin and PPAR{gamma}, a major transcription factor for adiponectin, in 3T3-L1, murine pre-adipocytes cell line, without promoting accumulation of lipid droplets. Ascofuranone induced expression of adiponectin, and increases the promoter activity of adiponectin and PPRE, PPAR response element, as comparably as a PPAR{gamma} agonist, rosiglitazone, that stimulates lipid accumulation in the preadipocyte cell line. Moreover, inhibitors for MEK and JNK, like ascofuranone, considerably increased the expression of adiponectin and PPAR{gamma}, while a p38 inhibitor significantly suppressed. Ascofuranone significantly suppressed ERK phosphorylation, while increasing p38 phosphorylation, during adipocyte differentiation program. These results suggest that ascofuranone regulates the expression of adiponectin and PPAR{gamma} through the modulation of MAP kinase family members.

Chang, Young-Chae, E-mail: ycchang@cu.ac.kr [Research Institute of Biomedical Engineering and Department of Medicine, Catholic University of Daegu School of Medicine, Daegu 705-718 (Korea, Republic of)] [Research Institute of Biomedical Engineering and Department of Medicine, Catholic University of Daegu School of Medicine, Daegu 705-718 (Korea, Republic of); Cho, Hyun-Ji, E-mail: hjcho.dr@gmail.com [Research Institute of Biomedical Engineering and Department of Medicine, Catholic University of Daegu School of Medicine, Daegu 705-718 (Korea, Republic of)] [Research Institute of Biomedical Engineering and Department of Medicine, Catholic University of Daegu School of Medicine, Daegu 705-718 (Korea, Republic of)

2012-06-08

122

Deletion of the thyroid hormone receptor 1 prevents the structural alterations of the cerebellum induced by hypothyroidism  

Microsoft Academic Search

Thyroid hormone (T3) controls critical aspects of cerebellar development, such as migration of postmitotic granule cells and terminal differentiation of Purkinje cells. T3 acts through nuclear receptors (TR) of two types, TR1 and TR, that either repress or activate gene expression. We have analyzed the cerebellar structure of developing mice lacking the TR1 isoform, which normally accounts for about 80%

Beatriz Morte; Jimena Manzano; Thomas Scanlan; Björn Vennström; Juan Bernal

2002-01-01

123

Mass-spectrometric analysis of agonist-induced retinoic acid receptor gamma conformational change.  

PubMed Central

Apo and holo forms of retinoic acid receptors, and other nuclear receptors, display differential sensitivity to proteolytic digestion that likely reflects the distinct conformational states of the free and liganded forms of the receptor. We have developed a method for rapid peptide mapping of holo-retinoic acid receptor gamma that utilizes matrix-assisted laser-desorption-ionization time-of-flight MS to identify peptide fragments that are derived from the partially proteolysed holo-receptor. The peptide maps of retinoic acid receptor gamma bound by four different agonists were identical, suggesting that all four ligands induced a similar conformational change within the ligand-binding domain of the receptor. In all cases, this agonist-induced conformational change promoted the direct association of retinoic acid receptor gamma with the transcriptional co-activator p300 and inhibited interaction of the receptor with the nuclear receptor co-repressor. SR11253, a compound previously reported to exert mixed retinoic acid receptor gamma agonist/antagonist activities in cultured cells, was found to bind directly to, but only weakly altered the protease-sensitivity of, the receptor and failed to promote interaction of the receptor with p300 or induce dissociation of receptor-nuclear receptor co-repressor complexes. This technique should be generally applicable to other members of the nuclear receptor superfamily that undergo an induced structural alteration upon agonist or antagonist binding, DNA binding and/or protein-protein interaction. PMID:11829754

Peterson, Valerie J; Barofsky, Elisabeth; Deinzer, Max L; Dawson, Marcia I; Feng, Kai-Chia; Zhang, Xiao-kun; Madduru, Machender R; Leid, Mark

2002-01-01

124

Antigen(s)-specific tumour-infiltrating lymphocytes from tumour induced by human herpes virus-6 (HHV-6) DNA transfected NIH 3T3 transformants.  

PubMed Central

Tumour infiltrating lymphocytes (TIL) have recently been shown to mediate potent therapeutic effects in certain malignancies in mice and in humans. To understand the mechanism of TIL immunotherapy it would be advantageous to generate tumour-specific TIL and to study a defined system of TIL and target cells in which the tumour epitope(s) recognized by TIL might be identified. We have established tumourigenic cell lines by transfection of NIH 3T3 cells with the entire genome of human herpesvirus-6 (HHV-6) and its small fragment (about 5% of the viral DNA sequence). Injection of these cells into nude mice produced tumours termed G-2T and 14-2T, respectively. Cell lines derived from these tumours when injected in NIH Swiss mice produced tumours, G-2TS and 14-2TS, respectively. We have generated TIL from G-2TS tumour that can kill G-2TS tumour cells in vitro but not other related tumours (14-2TS or MCA-106). These TIL can be expanded between 2-6.5 every 3-5 days. The TIL proliferated in tissue culture in response to recombinant interleukin-2 and interleukin-4 and maintained their tumor specificity for up to 6 months in vitro. Their phenotype was Thy 1.2+, Lyt-2+ and L3T4-. The availability of such tumour-specific stable TIL lines and specific viral-transformed targets will provide an opportunity to characterize the tumour-associated antigen critical for the specific cytotoxicity in this system and thereby to clarify the mechanism of this promising immunological approach to cancer therapy. Images Fig. 1 PMID:1703057

Puri, R K; Leland, P; Razzaque, A

1991-01-01

125

2-Methoxy-4-vinylphenol can induce cell cycle arrest by blocking the hyper-phosphorylation of retinoblastoma protein in benzo[a]pyrene-treated NIH3T3 cells  

SciTech Connect

Research highlights: {yields} 2M4VP activated the expression of p21 and p15 protein, and down-regulated the expression of cyclin D1 and cyclin E. {yields} 2M4VP inhibited hyper-phosphorylation of Rb protein. {yields} 2M4VP induced cell cycle arrest from G1 to S. {yields} 2M4VP inhibited hyper-proliferation of the cells in BaP-treated cells. {yields} 2M4VP induces growth arrest of BaP-treated cells by blocking hyper-phosphorylation of Rb via regulating the expression of cell cycle-related proteins. -- Abstract: Benzo[a]pyrene (BaP) is an environment carcinogen that can enhance cell proliferation by disturbing the signal transduction pathways in cell cycle regulation. In this study, the effects of 2M4VP on cell proliferation, cell cycle and cell cycle regulatory proteins were studied in BaP-treated NIH 3T3 cells to establish the molecular mechanisms of 2M4VP as anti-proliferative agents. 2M4VP exerted a dose-dependent inhibitory effect on cell growth correlated with a G1 arrest. Analysis of G1 cell cycle regulators expression revealed 2M4VP increased expression of CDK inhibitor, p21Waf1/Cip1 and p15 INK4b, decreased expression of cyclin D1 and cyclin E, and inhibited kinase activities of CDK4 and CDK2. However, 2M4VP did not affect the expression of CDK4 and CDK2. Also, 2M4VP inhibited the hyper-phosphorylation of Rb induced by BaP. Our results suggest that 2M4VP induce growth arrest of BaP-treated NIH 3T3 cells by blocking the hyper-phosphorylation of Rb via regulating the expression of cell cycle-related proteins.

Jeong, Jin Boo [Bioresource Sciences, Andong National University, Andong 760749 (Korea, Republic of)] [Bioresource Sciences, Andong National University, Andong 760749 (Korea, Republic of); Jeong, Hyung Jin, E-mail: jhj@andong.ac.kr [Bioresource Sciences, Andong National University, Andong 760749 (Korea, Republic of)

2010-10-01

126

The estrogen receptor ?-PI3K/Akt pathway mediates the cytoprotective effects of tocotrienol in a cellular Parkinson's disease model.  

PubMed

Tocotrienols (T3s) are members of the vitamin E family, have antioxidant properties, and are promising candidates for neuroprotection in the pathogenesis of neurodegenerative disorders such as Parkinson's disease (PD). However, whether their antioxidant capacities are required for their cytoprotective activity remains unclear. In this regard, the antioxidant-independent cytoprotective activity of T3s has received considerable attention. Here, we investigated the signaling pathways that are induced during T3-dependent cytoprotection of human neuroblastoma SH-SY5Y cells, as these cells are used to model certain elements of PD. T3s were cytoprotective against 1-methyl-4-phenylpyridinium ion (MPP(+)) and other PD-related toxicities. ?T3 and ?T3 treatments led to marked activation of the PI3K/Akt signaling pathway. Furthermore, we identified estrogen receptor (ER) ? as an upstream mediator of PI3K/Akt signaling following ?T3/?T3 stimulation. Highly purified ?T3/?T3 bound to ER? directly in vitro, and knockdown of ER? in SH-SY5Y cells abrogated both ?T3/?T3-dependent cytoprotection and Akt phosphorylation. Since membrane-bound ER? was important for the signal-related cytoprotective effects of ?T3/?T3, we investigated receptor-mediated caveola formation as a candidate for the early events of signal transduction. Knockdown of caveolin-1 and/or caveolin-2 prevented the cytoprotective effects of ?T3/?T3, but did not affect Akt phosphorylation. This finding suggests that T3s and, in particular, ?T3/?T3, exhibit not only antioxidant effects but also a receptor signal-mediated protective action following ER?/PI3K/Akt signaling. Furthermore, receptor-mediated caveola formation is an important event during the early steps following T3 treatment. PMID:24768803

Nakaso, Kazuhiro; Tajima, Naoko; Horikoshi, Yosuke; Nakasone, Masato; Hanaki, Takehiko; Kamizaki, Kouki; Matsura, Tatsuya

2014-09-01

127

Nociceptin/Orphanin FQ Receptor Activation Attenuates Antinociception Induced by Mixed Nociceptin/Orphanin FQ/?-Opioid Receptor Agonists  

PubMed Central

Activation of brain nociceptin/orphanin FQ (NOP) receptors leads to attenuation of ?-opioid receptor (MOP receptor)-mediated antinociception. Buprenorphine, a high-affinity partial MOP receptor agonist also binds to NOP receptors with 80 nM affinity. The buprenorphine-induced inverted U-shaped dose-response curve for antinociception may be due to NOP receptor activation, given that, in the presence of the NOP receptor antagonist, 1-[(3R,4R)-1-cyclooctylmethyl-3-hydroxymethyl-4-piperidyl]-3-ethyl-1,3-dihydro-2H-benzimidazol-2-one (J113397), or in NOP receptor knockout mice, buprenorphine has a steeper dose-response curve and acts as a full agonist. To further explore the involvement of the direct activation of NOP receptors by buprenorphine and other compounds that activate both NOP and MOP receptors, the antinociceptive effects of 1-(1-(2,3,3?,4,5,6-hexahydro-1H-phenalen-1-yl)piperidin-4-yl)-indolin-2-one. (SR16435), 3-ethyl-1-(1-(4-isopropylcyclohexyl)piperidin-4-yl)-indolin-2-one (SR16507), buprenorphine, pentazocine, and morphine, compounds with varying levels of MOP and NOP receptor affinity and efficacy, were assessed in mice using the tail-flick assay. The ability of the selective NOP receptor antagonist (?)-cis-1-methyl-7-[[4-(2,6-dichlorophenyl)piperidin-1-yl]methyl]-6,7,8,9-tetrahydro-5H-benzocyclohepten-5-ol (SB-612111) to potentiate antinociception induced by the above compounds was examined to investigate whether activation of NOP receptors leads to attenuation of MOP receptor-mediated antinociception. SB-612111 potentiated antinociception induced by buprenorphine and the other mixed NOP/MOP receptor agonists SR16435 and SR16507. However, SB-612111 had no effect on pentazocine or morphine antinociception, two compounds with no NOP receptor-binding affinity. These results further support the hypothesis that activation of NOP receptors can lead to attenuation of MOP receptor-mediated antinociception elicited by mixed NOP/MOP receptor compounds such as buprenorphine, SR16435, and SR16507 and that, although buprenorphine has low efficacy in vitro, it has significant NOP receptor agonist activity in vivo. PMID:19713488

Khroyan, Taline V.; Polgar, Willma E.; Jiang, Faming; Zaveri, Nurulain T.

2009-01-01

128

Nociceptin/orphanin FQ receptor activation attenuates antinociception induced by mixed nociceptin/orphanin FQ/mu-opioid receptor agonists.  

PubMed

Activation of brain nociceptin/orphanin FQ (NOP) receptors leads to attenuation of mu-opioid receptor (MOP receptor)-mediated antinociception. Buprenorphine, a high-affinity partial MOP receptor agonist also binds to NOP receptors with 80 nM affinity. The buprenorphine-induced inverted U-shaped dose-response curve for antinociception may be due to NOP receptor activation, given that, in the presence of the NOP receptor antagonist, 1-[(3R,4R)-1-cyclooctylmethyl-3-hydroxymethyl-4-piperidyl]-3-ethyl-1,3-dihydro-2H-benzimidazol-2-one (J113397), or in NOP receptor knockout mice, buprenorphine has a steeper dose-response curve and acts as a full agonist. To further explore the involvement of the direct activation of NOP receptors by buprenorphine and other compounds that activate both NOP and MOP receptors, the antinociceptive effects of 1-(1-(2,3,3alpha,4,5,6-hexahydro-1H-phenalen-1-yl)piperidin-4-yl)-indolin-2-one. (SR16435), 3-ethyl-1-(1-(4-isopropylcyclohexyl)piperidin-4-yl)-indolin-2-one (SR16507), buprenorphine, pentazocine, and morphine, compounds with varying levels of MOP and NOP receptor affinity and efficacy, were assessed in mice using the tail-flick assay. The ability of the selective NOP receptor antagonist (-)-cis-1-methyl-7-[[4-(2,6-dichlorophenyl)piperidin-1-yl]methyl]-6,7,8,9-tetrahydro-5H-benzocyclohepten-5-ol (SB-612111) to potentiate antinociception induced by the above compounds was examined to investigate whether activation of NOP receptors leads to attenuation of MOP receptor-mediated antinociception. SB-612111 potentiated antinociception induced by buprenorphine and the other mixed NOP/MOP receptor agonists SR16435 and SR16507. However, SB-612111 had no effect on pentazocine or morphine antinociception, two compounds with no NOP receptor-binding affinity. These results further support the hypothesis that activation of NOP receptors can lead to attenuation of MOP receptor-mediated antinociception elicited by mixed NOP/MOP receptor compounds such as buprenorphine, SR16435, and SR16507 and that, although buprenorphine has low efficacy in vitro, it has significant NOP receptor agonist activity in vivo. PMID:19713488

Khroyan, Taline V; Polgar, Willma E; Jiang, Faming; Zaveri, Nurulain T; Toll, Lawrence

2009-12-01

129

A platelet-activating factor (PAF) receptor deficiency exacerbates diet-induced obesity but PAF/PAF receptor signaling does not contribute to the development of obesity-induced chronic inflammation.  

PubMed

Platelet-activating factor (PAF) is a well-known phospholipid that mediates acute inflammatory responses. In the present study, we investigated whether PAF/PAF receptor signaling contributed to chronic inflammation in the white adipose tissue (WAT) of PAF receptor-knockout (PAFR-KO) mice. Body and epididymal WAT weights were higher in PAFR-KO mice fed a high-fat diet (HFD) than in wild-type (WT) mice. TNF-? mRNA expression levels in epididymal WAT and the infiltration of CD11c-positive macrophages into epididymal WAT, which led to chronic inflammation, were also elevated in HFD-fed PAFR-KO mice. HFD-fed PAFR-KO mice had higher levels of fasting serum glucose than HFD-fed WT mice as well as impaired glucose tolerance. Although PAF receptor signaling up-regulated the expression of TNF-? and lipopolysaccharide induced the expression of acyl-CoA:lysophosphatidylcholine acyltransferase 2 (LPCAT2) mRNA in bone marrow-derived macrophages, no significant differences were observed in the expression of LPCAT2 mRNA and PAF levels in epididymal WAT between HFD-fed mice and normal diet-fed mice. In addition to our previous finding in which energy expenditure in PAF receptor (PAFR)-deficient mice was low due to impaired brown adipose tissue function, the present study demonstrated that PAF/PAF receptor signaling up-regulated the expression of Ucp1 mRNA, which is essential for cellular thermogenesis, in 3T3-L1 adipocytes. We concluded that the marked accumulation of abdominal fat due to HFD feeding led to more severe chronic inflammation in WAT, which is associated with glucose metabolism disorders, in PAFR-KO mice than in WT mice, and PAF/PAF receptor signaling may regulate energy expenditure and adiposity. PMID:25577975

Yamaguchi, Masahiko; Matsui, Masakazu; Higa, Ryoko; Yamazaki, Yasuhiro; Ikari, Akira; Miyake, Masaki; Miwa, Masao; Ishii, Satoshi; Sugatani, Junko; Shimizu, Takao

2015-02-15

130

ZINC-INDUCED EGF RECEPTOR SIGNALING REQUIRES SRC-MEDIATED PHOSPHORYLATION OF THE EGF RECEPTOR ON TYROSINE 845 (Y845)  

EPA Science Inventory

ZINC-INDUCED EGF RECEPTOR SIGNALING REQUIRES Src-MEDIATED PHOSPHORYLATION OF THE EGF RECEPTOR ON TYROSINE 845 (Y845) Weidong Wu1, Lee M. Graves2, Gordon N. Gill3 and James M. Samet4 1Center for Environmental Medicine and Lung Biology; 2Department of Pharmacology, University o...

131

A GTP-binding adapter protein couples TRAIL receptors to apoptosis-inducing proteins  

Microsoft Academic Search

Apoptosis-inducing tumor necrosis factor (TNF) family receptors recruit the proforms of caspase family cell death proteases to ligand-receptor complexes through interactions with intracellular adapter proteins. We have found that the GTP-binding protein DAP3 binds directly (with high affinity) to the death domain of TNF-related apoptosis-inducing ligand (TRAIL) receptors, and is required for TRAIL-induced apoptosis. DAP3 also associates with the pro-caspase-8–binding

Tadaaki Miyazaki; John C. Reed

2001-01-01

132

Nuclear Receptors: Mediators And Modifiers Of Inflammation-Induced Cholestasis  

PubMed Central

Inflammation-induced cholestasis (IIC) is a frequently occurring phenomenon. A central role in its pathogenesis is played by nuclear receptors (NRs). These ligand-activated transcription factors not only regulate basal expression of hepatobiliary transport systems, but also mediate adaptive responses and possess anti-inflammatory characteristics. The latter two functions may be exploited in the search for new treatments for IIC and likely for cholestasis in general as well. Current knowledge of the pathogenesis of IIC and the dual role NRs in this process are reviewed. Special interest is given to the use of NRs as potential targets for intervention. PMID:19273222

Mulder, Jaap; Karpen, Saul J.; Tietge, Uwe J.F.; Kuipers, Folkert

2014-01-01

133

Estrogen receptors' neuroprotective effect against glutamate-induced neurotoxicity.  

PubMed

Glutamate is the most abundant excitatory brain neurotransmitter that has important functional significance with respect to neurodegenerative conditions. Glutamate-mediated excitotoxicity and neurodegeneration in Alzheimer's disease (AD) has been gradually becoming elucidated recently. Excessive release of glutamate induces an increase in intracellular Ca(2+) levels, thus triggers a cascade of cellular responses, ultimately leading to neuronal cell death. This type of neuronal damage induced by over-excitation has been proposed to be involved in a number of neuropathological conditions, ranging from acute insults to chronic neurodegenerative disorders. Estrogen could be effective in modulating glutamate-induced neurotoxicity and the protective responsivenesses are mostly estrogen receptors (ERs)-dependent. However, the mechanism underlying estrogen's neuroprotective effect is not fully clarified and is complicated by the presence of several distinct ER types. So a deeper research into the neuroprotection of ERs might be informative about the positive effect that estrogen might have on ageing-related cognitive changes. Extensive studies have indicated the neuroprotective effects of ERs against glutamate-induced neurotoxicity. The purpose of this review is to elucidate ERs' neuroprotective effects against glutamate-induced cytotoxicity and explore new ways to prevent and cure neurotoxicity-associated neurodegenerative disorders. PMID:25228013

Lan, Yu-Long; Zhao, Jie; Li, Shao

2014-11-01

134

Mutations of CpG dinucleotides located in the triiodothyronine (T3)-binding domain of the thyroid hormone receptor (TR) beta gene that appears to be devoid of natural mutations may not be detected because they are unlikely to produce the clinical phenotype of resistance to thyroid hormone.  

PubMed Central

Thyroid hormone receptor (TR) beta gene mutations identified in patients with resistance to thyroid hormone (RTH) revealed two clusters ("hot" areas) of mutations (RTHmut) in the triiodothyronine (T3)-binding domain. Furthermore, 45% of RTHmuts and 90% of recurring mutations are located in CpG dinucleotides ("hot spots"). To investigate why the region between the two hot areas lacks RTHmuts, we produced 10 artificial mutant TR beta s (ARTmut) in this "cold" region according to the hot spot rule (C-->T or G-->A substitutions in CpGs). The properties of ARTmuts were compared with those of six RTHmuts. Among all RTHmuts, R320H manifesting a mild form of RTH showed the least impairment of T3-binding affinity (Ka). In contrast, Ka was normal in six ARTmuts (group A), reduced to a lesser extent than R320H in three (group B), and one that was truncated (R410X) did not bind T3. All RTHmuts had impaired ability to transactivate T3-responsive elements and exhibited a strong dominant negative effect on cotransfected wild-type TR beta. Group B and A ARTmuts had minimally impaired or normal transactivation and weak or no dominant negative effect, respectively. R410X showed neither transactivation nor dominant negative effect. Natural mutations expected to occur in the cold region of TR beta should fail to manifest as RTH (group A) or should escape detection (group B) since the serum thyroid hormone levels required to compensate for the reduced binding affinity should be inferior to those found in subjects with R320H. R410X would manifest RTH only in the homozygote state. The cold region of the putative T3-binding domain is relatively insensitive to amino acid changes and, thus, may not be involved in a direct interaction with T3. Images PMID:8040316

Hayashi, Y; Sunthornthepvarakul, T; Refetoff, S

1994-01-01

135

Antiobesity Effects of an Edible Halophyte Nitraria retusa Forssk in 3T3-L1 Preadipocyte Differentiation and in C57B6J/L Mice Fed a High Fat Diet-Induced Obesity  

PubMed Central

Nitraria retusa is an edible halophyte, used in Tunisia for several traditional medicine purposes. The present study investigated the antiobesity effects of Nitraria retusa ethanol extract (NRE) in 3T3-L1 cells using different doses and in high-fat diet-induced obesity in mice. Male C57B6J/L mice were separately fed a normal diet (ND) or a high-fat diet (HFD) and daily administrated with NRE (50, 100?mg/kg) or one for 2 days with Naringenin (10?mg/kg). NRE administration significantly decreased body weight gain, fat pad weight, serum glucose, and lipid levels in HFD-induced obese mice. To elucidate the mechanism of action of NRE, the expression of genes involved in lipid and carbohydrate metabolism were measured in liver. Results showed that mice treated with NRE demonstrated a significant decrease in cumulative body weight and fat pad weight, a significant lowering in glucose and triglycerides serum levels, and an increase in the HDL-cholesterol serum level. Moreover mRNA expression results showed an enhancement of the expression of genes related to liver metabolism. Our findings suggest that NRE treatment had a protective or controlling effect against a high fat diet-induced obesity in C57B6J/L mice through the regulation of expression of genes involved in lipolysis and lipogenesis and thus the enhancement of the lipid metabolism in liver. PMID:24367387

Zar Kalai, Feten; Han, Junkyu; Ksouri, Riadh; El Omri, Abdelfatteh; Abdelly, Chedly; Isoda, Hiroko

2013-01-01

136

Lipolytic and antiadipogenic effects of (3,3-dimethylallyl) halfordinol on 3T3-L1 adipocytes and high fat and fructose diet induced obese C57/BL6J mice.  

PubMed

Aegle marmelos Correa., (Rutaceae) is a medium sized tree distributed in South East Asia and used traditionally for the management of obestiy and diabetes. In this study the lipolytic and antiadipogenic effects of (3,3-dimethylallyl) halfordinol (Hfn) isolated from leaves of A. marmelos have been investigated. Intracellular lipid accumulation was measured by oil red O staining and glycerol secretion. The expression of genes related to adipocyte differentiation was analyzed by reverse transcriptase-polymerase chain reaction (RT-PCR). Hfn decreased intracellular triglyceride accumulation and increased glycerol release in a dose dependent manner (5-20 ?g/ml) in differentiated 3T3-L1 adipocytes. In high fat diet fed C57/BL 6J mice, treatment with Hfn for four weeks reduced plasma glucose, insulin and triglyceride levels and showed a significant reduction in total adipose tissue mass by 37.85% and visceral adipose tissue mass by 62.99% at 50mg/kg b.w. concentration. RT-PCR analyses indicated that Hfn decreased the expression of peroxisome proliferator-activated receptor ? (PPAR?) and CCAAT enhancer binding protein ? (CEBP?) and increased the expression of sterol regulatory enzyme binding protein (SREBP-1c), peroxisome proliferator-activated receptor ? (PPAR?), Adiponectin and Glucose transporter protein 4 (GLUT4) compared to the high fat diet group. These results suggested that Hfn decreased adipocyte differentiation and stimulated lipolysis of adipocytes. This study justifies the folklore medicinal uses and claims about the therapeutic values of this plant for the management of insulin resistance and obesity. PMID:24952133

Saravanan, Munisankar; Pandikumar, Perumal; Saravanan, Subramaniam; Toppo, Erenius; Pazhanivel, Natesan; Ignacimuthu, Savarimuthu

2014-10-01

137

SirT3 Regulates the Mitochondrial Unfolded Protein Response  

PubMed Central

The mitochondria of cancer cells are characterized by elevated oxidative stress caused by reactive oxygen species (ROS). Such an elevation in ROS levels contributes to mitochondrial reprogramming and malignant transformation. However, high levels of ROS can cause irreversible damage to proteins, leading to their misfolding, mitochondrial stress, and ultimately cell death. Therefore, mechanisms to overcome mitochondrial stress are needed. The unfolded protein response (UPR) triggered by accumulation of misfolded proteins in the mitochondria (UPRmt) has been reported recently. So far, the UPRmt has been reported to involve the activation of CHOP and estrogen receptor alpha (ER?). The current study describes a novel role of the mitochondrial deacetylase SirT3 in the UPRmt. Our data reveal that SirT3 acts to orchestrate two pathways, the antioxidant machinery and mitophagy. Inhibition of SirT3 in cells undergoing proteotoxic stress severely impairs the mitochondrial network and results in cellular death. These observations suggest that SirT3 acts to sort moderately stressed from irreversibly damaged organelles. Since SirT3 is reported to act as a tumor suppressor during transformation, our findings reveal a dual role of SirT3. This novel role of SirT3 in established tumors represents an essential mechanism of adaptation of cancer cells to proteotoxic and mitochondrial stress. PMID:24324009

Papa, Luena

2014-01-01

138

Isobavachalcone suppresses expression of inducible nitric oxide synthase induced by Toll-like receptor agonists.  

PubMed

Toll-like receptors (TLRs) play an important role by recognizing many pathogen-associated molecular patterns and inducing innate immunity. Dysregulated activation of TLR signaling pathways induces the activation of various transcription factors such as nuclear factor-?B, leading to the induction of pro-inflammatory gene products such as inducible nitric oxide synthase (iNOS). The present study investigated the effect of isobavachalcone (IBC), a natural chalcone component of Angelica keiskei, on inflammation by modulating iNOS expression induced by TLR agonists in murine macrophages. IBC suppressed iNOS expression induced by macrophage-activating lipopeptide 2-kDa, polyriboinosinic polyribocytidylic acid, or lipopolysaccharide. These results indicate the potential of IBC as a potent anti-inflammatory drug. PMID:23164691

Shin, Hwa-Jeong; Shon, Dong-Hwa; Youn, Hyung-Sun

2013-01-01

139

Prostaglandin E2-induced up-regulation of c-fos messenger ribonucleic acid is primarily mediated by 3',5'-cyclic adenosine monophosphate in MC3T3-E1 osteoblasts  

NASA Technical Reports Server (NTRS)

The mechanism by which the proto-oncogene, c-fos, is up-regulated in response to PGE2 in the mouse osteoblastic (MC3T3-E1) cell line was investigated using RT-PCR. c-fos messenger RNA up-regulation by dmPGE2 is rapid, starting 10 min post stimulation, and transient. The specific protein kinase A (PKA) inhibitor, H89, inhibited c-fos induction. Moreover, down-regulation of protein kinase C (PKC) activity by chronic TPA treatment had no effect on the induction of c-fos by dmPGE2. We conclude that up-regulation of c-fos by dmPGE2 is primarily dependent on PKA in MC3T3-E1 osteoblasts. In S49 lymphoma wild-type but not S49 cyc- cells, which are deficient in cAMP signaling, dmPGE2 up-regulates c-fos and increases cell growth compared with unstimulated cells. Thus in S49 lymphoma cells, c-fos induction by PGE2 is also dependent on cAMP signaling. The minimal c-fos promoter region required for dmPGE2-induced expression was identified by transfecting c-fos promoter deletion constructs coupled to the chloramphenicol acetyltransferase (CAT) reporter gene into Vero cells. Transfection of a plasmid containing 99 bp c-fos proximal promoter was sufficient to direct c-fos/CAT expression following stimulation with dmPGE2. Because induction of c-fos is mediated by cAMP, these data are consistent with activation of c-fos via the CRE/ATF cis element.

Fitzgerald, J.; Dietz, T. J.; Hughes-Fulford, M.

2000-01-01

140

Guggulsterone activates multiple nuclear receptors and induces CYP3A gene expression through the pregnane X receptor.  

PubMed

Gugulipid is an extract of the guggul tree, Commiphora mukul, that is used to treat hyperlipidemia in humans. The lipid-lowering activity is found in the stereoisomers and plant sterols Z-guggulsterone and E-guggulsterone. The molecular basis for the lipid-lowering action of guggulsterone has been suggested to be antagonism of the farnesoid X receptor, a member of the nuclear receptor superfamily of ligand-activated transcription factors. To determine whether guggulsterone has the ability to function as an agonist of other nuclear receptor family members, we screened a panel of these proteins for their ability to transactivate reporter genes. Here, we show that guggulsterones activate the estrogen receptor alpha isoform, progesterone receptor, and pregnane X receptor. Concentration-response analysis using reporter gene assays indicate that guggulsterones activate these three receptors with EC(50) values in the low micromolar range. Furthermore, we show that guggulsterone-mediated activation of the pregnane X receptor induces the expression of CYP3A genes in both rodent and human hepatocytes. Protein interaction assays indicate that guggulsterones interact directly with pregnane X receptor, thereby modulating interaction with protein cofactors. We introduce a novel method to screen herbal remedies for their ability to activate pregnane X receptor. Pregnane X receptor activation is known to cause herb-drug interactions, and our data suggest that gugulipid therapy should be used cautiously in patients taking prescription medications that are metabolized by CYP3A family members. Moreover, our data suggest the need for additional studies of guggulsterones agonist activity against estrogen receptor alpha isoform and the progesterone receptor. PMID:15075359

Brobst, Dan E; Ding, Xunshan; Creech, Katrina L; Goodwin, Bryan; Kelley, Brian; Staudinger, Jeff L

2004-08-01

141

Ghrelin inhibits the apoptosis of MC3T3-E1 cells through ERK and AKT signaling pathway  

SciTech Connect

Ghrelin is a 28-amino-acid peptide that acts as a natural endogenous ligand of the growth hormone secretagogue receptor (GHSR) and strongly stimulates the release of growth hormone from the hypothalamus–pituitary axis. Previous studies have identified the important physiological effects of ghrelin on bone metabolism, such as regulating proliferation and differentiation of osteoblasts, independent of GH/IGF-1 axis. However, research on effects and mechanisms of ghrelin on osteoblast apoptosis is still rare. In this study, we identified expression of GHSR in MC3T3-E1 cells and determined the effects of ghrelin on the apoptosis of osteoblastic MC3T3-E1 cells and the mechanism involved. Our data demonstrated that ghrelin inhibited the apoptosis of osteoblastic MC3T3-E1 cells induced by serum deprivation, as determined by terminal deoxynucleotidyl transferase-mediated deoxyribonucleotide triphosphate nick end-labeling (TUNEL) and ELISA assays. Moreover, ghrelin upregulated Bcl-2 expression and downregulated Bax expression in a dose-dependent manner. Our study also showed decreased activated caspase-3 activity under the treatment of ghrelin. Further study suggested that ghrelin stimulated the phosphorylation of ERK and AKT. Pretreatment of cells with the ERK inhibitor PD98059, PI3K inhibitor LY294002, and GHSR-siRNA blocked the ghrelin-induced activation of ERK and AKT, respectively; however, ghrelin did not stimulate the phosphorylation of p38 or JNK. PD90859, LY294002 and GHSR-siRNA attenuated the anti-apoptosis effect of ghrelin in MC3T3-E1 cells. In conclusion, ghrelin inhibits the apoptosis of osteoblastic MC3T3-E1 cells induced by serum deprivation, which may be mediated by activating the GHSR/ERK and GHSR/PI3K/AKT signaling pathways. - Highlights: • We explored the effects of ghrelin on serum deprivation-induced MC3T3-E1 cells apoptosis. • Both ELISA and TUNEL were used to detect the apoptosis. • The receptor of ghrelin, GHSR, was expressed in MC3T3-E1 cells. • Both Akt and ERK are critical adaptor molecules to mediate the effects of ghrelin.

Liang, Qiu-Hua; Liu, Yuan; Wu, Shan-Shan; Cui, Rong-Rong; Yuan, Ling-Qing, E-mail: allenylq@hotmail.com; Liao, Er-Yuan, E-mail: eyliao@21cn.com

2013-11-01

142

Dextromethorphan attenuates trimethyltin-induced neurotoxicity via sigma1 receptor activation in rats.  

PubMed

We showed that dextromethorphan (DM) provides neuroprotective/anticonvulsant effects and that DM and its major metabolite, dextrorphan, have a high-affinity for sigma(1) receptors, but a low affinity for sigma(2) receptors. In addition, we found that DM has a higher affinity than DX for sigma(1) sites, whereas DX has a higher affinity than DM for PCP sites. We extend our earlier findings by showing that DM attenuated trimethyltin (TMT)-induced neurotoxicity (convulsions, hippocampal degeneration and spatial memory impairment) in rats. This attenuation was reversed by the sigma(1) receptor antagonist BD 1047, but not by the sigma(2) receptor antagonist ifenprodil. DM attenuates TMT-induced reduction in the sigma(1) receptor-like immunoreactivity of the rat hippocampus, this attenuation was blocked by the treatment with BD 1047, but not by ifenprodil. These results suggest that DM prevents TMT-induced neurotoxicity, at least in part, via sigma(1) receptor stimulation. PMID:17386960

Shin, Eun-Joo; Nah, Seung-Yeol; Chae, Jong Seok; Bing, Guoying; Shin, Seung Woo; Yen, Tran Phi Hoang; Baek, In-Hyuk; Kim, Won-Ki; Maurice, Tangui; Nabeshima, Toshitaka; Kim, Hyoung-Chun

2007-05-01

143

Central antinociception induced by ketamine is mediated by endogenous opioids and ?- and ?-opioid receptors.  

PubMed

It is generally believed that NMDA receptor antagonism accounts for most of the anesthetic and analgesic effects of ketamine, however, it interacts at multiple sites in the central nervous system, including NMDA and non-NMDA glutamate receptors, nicotinic and muscarinic cholinergic receptors, and adrenergic and opioid receptors. Interestingly, it was shown that at supraspinal sites, ketamine interacts with the ?-opioid system and causes supraspinal antinociception. In this study, we investigated the involvement of endogenous opioids in ketamine-induced central antinociception. The nociceptive threshold for thermal stimulation was measured in Swiss mice using the tail-flick test. The drugs were administered via the intracerebroventricular route. Our results demonstrated that the opioid receptor antagonist naloxone, the ?-opioid receptor antagonist clocinnamox and the ?-opioid receptor antagonist naltrindole, but not the ?-opioid receptor antagonist nor-binaltorphimine, antagonized ketamine-induced central antinociception in a dose-dependent manner. Additionally, the administration of the aminopeptidase inhibitor bestatin significantly enhanced low-dose ketamine-induced central antinociception. These data provide evidence for the involvement of endogenous opioids and ?- and ?-opioid receptors in ketamine-induced central antinociception. In contrast, ?-opioid receptors not appear to be involved in this effect. PMID:24675031

Pacheco, Daniela da Fonseca; Romero, Thiago Roberto Lima; Duarte, Igor Dimitri Gama

2014-05-01

144

Cdc42 induces EGF receptor protein accumulation and promotes EGF receptor nuclear transport and cellular transformation.  

PubMed

Cdc42 is a Ras-related small GTP-binding protein. A previous study has shown that Cdc42 binding to the ? subunit of the coatomer protein complex (?COP) is essential for Cdc42-regulated cellular transformation, but the molecular mechanism involved is not well understood. Here, we demonstrate that constitutively-active Cdc42 binding to ?COP induced the accumulation of epithelial growth factor receptor (EGFR) in the cells, sustained EGF-stimulated extracellular signal-regulated kinase (ERK), JUN amino-terminal kinase (JNK) and phosphoinositide 3-kinase (PI3K) signaling and promoted cell division. Moreover, constitutive Cdc42 activity facilitated the nuclear translocation of EGFR, and this indicates a novel mechanism through which Cdc42 might promote cellular transformation. PMID:25497016

Wang, Xiao-Yu; Gan, Ming-Xi; Li, Yong; Zhan, Wei-Hua; Han, Tian-Yu; Han, Xiao-Jian; Cheng, Jin-Quan; Wang, Jian-Bin

2015-01-16

145

Icariin induces osteoblast proliferation, differentiation and mineralization through estrogen receptor-mediated ERK and JNK signal activation.  

PubMed

Icariin, the main active flavonoid glucoside isolated from Herba epimedii (HEF), is an anabolic agent in bone that has been reported to prevent bone loss in ovariectomized rats and postmenopausal women. However, the molecular mechanism for this anabolic action of Icariin remain largely unknown. Here, we found that Icariin could promote MC3T3-E1 osteoblastic cell proliferation and reduce cell apoptosis, associated with increased mRNA levels of positive regulators of cell cycle gene Cyclin E and proliferating cell nuclear antigen (PCNA), decreaed mRNA level of negative regulator gene, Cyclin-dependent kinase 4 inhibitor B (Cdkn2B), and reduced caspase-3 activity. Icariin also enhanced MC3T3-E1 cell differentiation and mineralization demonstrated by increased the expression of differentiation markers, alkaline phosphatase (ALP) and collagen type I (Col I), and bone nodule formation via Alizarin red S staining. To characterize the underlying mechanisms, we examined the effect of Icariin on mitogen-activated protein kinase (MAPK) signaling. Icariin treatment rapidly induced extracellular signal-regulated kinase (ERK) and c-Jun N terminal kinase (JNK) activation but showed no effect on activation of p38 kinase. Furthermore, Icariin-mediated effects on osteoblasts were dramatically attenuated by treatment with specific inhibitors of MAPKs, U0126 (ERK inhibitor) and SP600125 (JNK inhibitor). Interestingly, treatment of osteoblasts with estrogen receptor antagonist ICI182780 attenuated Icariin-mediated effect of proliferation and mineralization, associated with suppression of ERK and JNK phosphorylation. These observations provide a potential mechanism of anabolic actions of Icariin involving ERK and JNK pathway by estrogen receptor. PMID:23764463

Song, Lige; Zhao, Jiashen; Zhang, Xiuzhen; Li, Hong; Zhou, Yun

2013-08-15

146

Histrionicotoxin enhances agonist-induced desensitization of acetylcholine receptor.  

PubMed Central

Dihydroisohistrionicotoxin inhibits acetylcholine receptor-dependent 22Na+ uptake of cultured chick muscle cells with a KI of 0.2 micrometer. The inhibition is noncompetitive with respect to agonists. The toxin enhances desensitization of the receptor by agonists which is accompanied by a 10-fold increase in receptor affinity for agonists. Dihydroisohistrionicotoxin increases the affinity of the desensitized form of the receptor for agonists but not antagonists. The results suggest that dihydroisohistrionicotoxin inhibits the acetylcholine receptor by causing an increase in the affinity of the desensitized form of the receptor for agonists and thereby stabilizing the desensitized state. PMID:272000

Burgermeister, W; Catterall, W A; Witkop, B

1977-01-01

147

Shikonin induces programmed necrosis-like cell death through the formation of receptor interacting protein 1 and 3 complex.  

PubMed

An alternative cell demise programmed necrosis has also been proposed when apoptotic machinery is impaired or blocked during tumor necrosis factor alpha (TNF?) stimulation. Shikonin (SKN), an herbal extract from the Chinese plant, has been reported to induce either apoptosis or necrosis depending on cell types or its concentrations. In this presentation, SKN caused cell death of NIH3T3 in a dose-dependent manner. Intriguingly, SKN-mediated cell death was in part protected by necrostatin-1 (Nec-1), a specific inhibitor of programmed necrosis, but not zVAD a pan-caspase inhibitor. SKN directly mediated cell death via receptor interacting protein1 and 3 (RIP1-RIP3) complex formation, which is required for TNF?-mediated programmed necrosis. Additionally, SKN-caused cell death was reversed by a reactive oxygen species (ROS) scavenger N-acetylcysteine (NAC) whereas TNF?-mediated necrosis was successfully protected by butylated hydroxyanisole (BHA), implying that ROS may be differentially derived from death inducing agents. Concurrently with the protective effect of the ROS scavenger or Nec-1 on TNF? or SKN, the RIP1-RIP3 complex was significantly affected in the presence of those agents. Here, it is highlighted that SKN as well as TNF? can directly mediate cell death via a pronecrotic complex, but ROS were generated via different routes depending on cell death-inducing agents. PMID:23261677

Park, Seungyeon; Shin, Heesuk; Cho, Youngsik

2013-05-01

148

Involvement of cholinergic nicotinic receptors in the menthol-induced gastric relaxation.  

PubMed

We have previously demonstrated that menthol reduces murine gastric tone in part through a neural mechanism, involving adrenergic pathways and reduction of ongoing release of acetylcholine from enteric nerves. In the present study we aimed to verify whether the gastric relaxation to menthol may be triggered by interaction with neural receptors or ionic channels proteins, such as transient receptor potential (TRP)-melastatin8 (TRPM8), TRP-ankyrin 1 (TRPA1), 5-hydroxytriptamine 3 (5-HT3) receptor or cholinergic nicotinic receptors. Spontaneous mechanical activity was detected in vitro as changes in intraluminal pressure from isolated mouse stomach. Menthol (0.3-30mM) induced gastric relaxation which was not affected by 5-benzyloxytryptamine, a TRPM8 receptor antagonist, HC030031, a TRPA1 channel blocker. In addition, allylisothiocyanate, a TRPA1 agonist, but not (2S,5R)-2-Isopropyl-N-(4-methoxyphenyl)-5-methylcyclohexanecarboximide, a selective TRPM8 agonist, induced gastric relaxation. Genic expression of TRPA1, but not of TRPM8, was revealed in mouse stomach. Indeed, menthol-induced gastric relaxation was significantly reduced by hexamethonium, cholinergic nicotinic receptor antagonist. Menthol, at concentrations that failed to affect gastric tone, reduced the contraction induced by dimethylphenylpiperazinium, nicotinic receptor agonist. The joint application of hexamethonium and atropine, muscarinc receptor antagonist, or hexamethonium and phentholamine, ?-adrenergic receptor antagonist, did not produce any additive reduction of the relaxant response to menthol. Lastly, ondansetron, a 5-HT3 receptor antagonist, was ineffective. In conclusion, our study suggests that nicotinic receptors, but not TRP and 5-HT3 receptors, are molecular targets for menthol inducing murine gastric relaxation, ultimately due to the reduction of acetylcholine release from enteric nerves. PMID:25446932

Amato, Antonella; Serio, Rosa; Mulè, Flavia

2014-12-15

149

Adenosine A2A receptor induces protein kinase A-dependent functional modulation of human ?3?4 nicotinic receptor  

PubMed Central

Abstract Adenosine modulates the function of nicotinic ACh receptors (nAChRs) in a variety of preparations, possibly through pathways involving protein kinase A (PKA), but these phenomena have not yet been investigated in detail. In this work we studied, using the patch clamp technique, the functional modulation of recombinant human ?3?4 nAChR by the A2A adenosine receptor, co-expressed in HEK cells. Tonic activation of A2A receptor slowed current decay during prolonged applications of nicotine and accelerated receptor recovery from desensitization. Together, these changes resulted into a more sustained current response upon multiple nicotine or ACh applications. These findings were confirmed in cultured mouse superior cervical ganglion neurones, which express nAChR containing the ?3 subunit together with ?2 and/or ?4 and A2A receptor. Expression of the A2A receptor in HEK cells also increased the apparent potency of nAChR for nicotine, further supporting a general A2A-induced gain of function for nAChR. These effects were dependent on PKA since the direct activation of PKA mimicked, and its inhibition prevented almost completely, the effects of the A2A receptor. Mutations of R385 and S388 in the cytoplasmic loop of the ?3 subunit abolished the functional modulation of nAChR induced by activation of A2A receptor, PKA and other Ser/Thr kinases, suggesting that this region constitutes a putative consensus site for these kinases. These data provide conclusive evidence that activation of the A2A receptor determines functional changes of human ?3?4 nAChR, through pathways involving PKA. PMID:21486776

Di Angelantonio, Silvia; Piccioni, Alessio; Moriconi, Claudia; Trettel, Flavia; Cristalli, Gloria; Grassi, Francesca; Limatola, Cristina

2011-01-01

150

Hyperthermia restores apoptosis induced by death receptors through aggregation-induced c-FLIP cytosolic depletion.  

PubMed

TRAIL is involved in immune tumor surveillance and is considered a promising anti-cancer agent owing to its limited side effects on healthy cells. However, some cancer cells display resistance, or become resistant to TRAIL-induced cell death. Hyperthermia can enhance sensitivity to TRAIL-induced cell death in various resistant cancer cell lines, including lung, breast, colon or prostate carcinomas. Mild heat shock treatment has been proposed to restore Fas ligand or TRAIL-induced apoptosis through c-FLIP degradation or the mitochondrial pathway. We demonstrate here that neither the mitochondria nor c-FLIP degradation are required for TRAIL-induced cell death restoration during hyperthermia. Our data provide evidence that insolubilization of c-FLIP, alone, is sufficient to enhance apoptosis induced by death receptors. Hyperthermia induced c-FLIP depletion from the cytosolic fraction, without apparent degradation, thereby preventing c-FLIP recruitment to the TRAIL DISC and allowing efficient caspase-8 cleavage and apoptosis. Hyperthermia-induced c-FLIP depletion was independent of c-FLIP DED2 FL chain assembly motif or ubiquitination-mediated c-FLIP degradation, as assessed using c-FLIP point mutants on lysine 167 and 195 or threonine 166, a phosphorylation site known to regulate ubiquitination of c-FLIP. Rather, c-FLIP depletion was associated with aggregation, because addition of glycerol not only prevented the loss of c-FLIP from the cytosol but also enabled c-FLIP recruitment within the TRAIL DISC, thus inhibiting TRAIL-induced apoptosis during hyperthermia. Altogether our results demonstrate that c-FLIP is a thermosensitive protein whose targeting by hyperthermia allows restoration of apoptosis induced by TNF ligands, including TRAIL. Our findings suggest that combining TRAIL agonists with whole-body or localized hyperthermia may be an interesting approach in cancer therapy. PMID:25675293

Morlé, A; Garrido, C; Micheau, O

2015-01-01

151

The chemokine monocyte chemoattractant protein-1 induces functional responses through dimerization of its receptor CCR2  

PubMed Central

Cytokines interact with hematopoietin superfamily receptors and stimulate receptor dimerization. We demonstrate that chemoattractant cytokines (chemokines) also trigger biological responses through receptor dimerization. Functional responses are induced after pairwise crosslinking of chemokine receptors by bivalent agonistic antichemokine receptor mAb, but not by their Fab fragments. Monocyte chemoattractant protein (MCP)-1-triggered receptor dimerization was studied in human embryonic kidney (HEK)-293 cells cotransfected with genes coding for the CCR2b receptor tagged with YSK or Myc sequences. After MCP-1 stimulation, immunoprecipitation with Myc-specific antibodies revealed YSK-tagged receptors in immunoblotting. Receptor dimerization also was validated by chemical crosslinking in both HEK-293 cells and the human monocytic cell line Mono Mac 1. Finally, we constructed a loss-of-function CCR2bY139F mutant that acted as a dominant negative, blocking signaling through the CCR2 wild-type receptor. This study provides functional support for a model in which the MCP-1 receptor is activated by ligand-induced homodimerization, allowing discussion of the similarities between bacterial and leukocyte chemotaxis. PMID:10097088

Rodríguez-Frade, José Miguel; Vila-Coro, Antonio J.; Martín de Ana, Ana; Albar, Juan Pablo; Martínez-A., Carlos; Mellado, Mario

1999-01-01

152

Hepatitis C Virus Induces the Cannabinoid Receptor 1  

PubMed Central

Background Activation of hepatic CB1 receptors (CB1) is associated with steatosis and fibrosis in experimental forms of liver disease. However, CB1 expression has not been assessed in patients with chronic hepatitis C (CHC), a disease associated with insulin resistance, steatosis and metabolic disturbance. We aimed to determine the importance and explore the associations of CB1 expression in CHC. Methods CB1 receptor mRNA was measured by real time quantitative PCR on extracted liver tissue from 88 patients with CHC (genotypes 1 and 3), 12 controls and 10 patients with chronic hepatitis B (CHB). The Huh7/JFH1 Hepatitis C virus (HCV) cell culture model was used to validate results. Principal Findings CB1 was expressed in all patients with CHC and levels were 6-fold higher than in controls (P<0.001). CB1 expression increased with fibrosis stage, with cirrhotics having up to a 2 fold up-regulation compared to those with low fibrosis stage (p<0.05). Even in mild CHC with no steatosis (F0-1), CB1 levels remained substantially greater than in controls (p<0.001) and in those with mild CHB (F0-1; p<0.001). Huh7 cells infected with JFH-1 HCV showed an 8-fold upregulation of CB1, and CB1 expression directly correlated with the percentage of cells infected over time, suggesting that CB1 is an HCV inducible gene. While HCV structural proteins appear essential for CB1 induction, there was no core genotype specific difference in CB1 expression. CB1 significantly increased with steatosis grade, primarily driven by patients with genotype 3 CHC. In genotype 3 patients, CB1 correlated with SREBP-1c and its downstream target FASN (SREBP-1c; R?=?0.37, FASN; R?=?0.39, p<0.05 for both). Conclusions/Significance CB1 is up-regulated in CHC and is associated with increased steatosis in genotype 3. It is induced by the hepatitis C virus. PMID:20862263

van der Poorten, David; Shahidi, Mahsa; Tay, Enoch; Sesha, Jayshree; Tran, Kayla; McLeod, Duncan; Milliken, Jane S.; Ho, Vikki; Hebbard, Lionel W.; Douglas, Mark W.; George, Jacob

2010-01-01

153

Acetylcholine receptor-inducing factor from chicken brain increases the level of mRNA encoding the receptor. alpha. subunit  

SciTech Connect

A 42-kDa glycoprotein isolated from chicken brain, referred to as acetylcholine receptor-inducing activity (ARIA), that stimulates the rate of incorporation of acetylcholine receptors into the surface of chicken myotubes may play a role in the nerve-induced accumulation of receptors at developing neuromuscular synapses. Using nuclease-protection assays, the authors have found that ARIA causes a 2- to 16-fold increase in the level of mRNA encoding the {alpha} subunit of the receptor, with little or no change in the levels of {gamma}- and {delta}-subunit messengers. ARIA also increases the amount of a putative nuclear precursor of {alpha}-subunit mRNA, consistent with an activation of gene transcription. These results suggest that the concentration of {alpha} subunit may limit the rate of biosynthesis of the acetylcholine receptors in chicken myotubes. They also indicate that neuronal factors can regulate the expression of receptor subunit genes in a selective manner. Tetrodotoxin, 8-bromo-cAMP, and forskolin also increase the amount of {alpha}-subunit mRNA, with little change in the amount of {gamma}- and {delta}-subunit mRNAs. Unlike ARIA, however, these agents have little effect on the concentration of the {alpha}-subunit nuclear precursor.

Harris, D.A.; Falls, D.L.; Dill-Devor, R.M.; Fischbach, G.D. (Washington Univ. School of Medicine, St. Louis, MO (USA))

1988-03-01

154

5-HT1A receptor blockade reverses GABAA receptor ?3 subunit-mediated anxiolytic effects on stress-induced hyperthermia  

PubMed Central

Rationale Stress-related disorders are associated with dysfunction of both serotonergic and GABAergic pathways, and clinically effective anxiolytics act via both neurotransmitter systems. As there is evidence that the GABAA and the serotonin receptor system interact, a serotonergic component in the anxiolytic actions of benzodiazepines could be present. Objectives The main aim of the present study was to investigate whether the anxiolytic effects of (non-)selective ? subunit GABAA receptor agonists could be reversed with 5-HT1A receptor blockade using the stress-induced hyperthermia (SIH) paradigm. Results The 5-HT1A receptor antagonist WAY-100635 (0.1–1 mg/kg) reversed the SIH-reducing effects of the non-?-subunit selective GABAA receptor agonist diazepam (1–4 mg/kg) and the GABAA receptor ?3-subunit selective agonist TP003 (1 mg/kg), whereas WAY-100635 alone was without effect on the SIH response or basal body temperature. At the same time, co-administration of WAY-100635 with diazepam or TP003 reduced basal body temperature. WAY-100635 did not affect the SIH response when combined with the preferential ?1-subunit GABAA receptor agonist zolpidem (10 mg/kg), although zolpidem markedly reduced basal body temperature. Conclusions The present study suggests an interaction between GABAA receptor ?-subunits and 5-HT1A receptor activation in the SIH response. Specifically, our data indicate that benzodiazepines affect serotonergic signaling via GABAA receptor ?3-subunits. Further understanding of the interactions between the GABAA and serotonin system in reaction to stress may be valuable in the search for novel anxiolytic drugs. PMID:20535452

van Oorschot, Ruud; Korte, S. Mechiel; Olivier, Berend; Groenink, Lucianne

2010-01-01

155

Glyphosate induces human breast cancer cells growth via estrogen receptors.  

PubMed

Glyphosate is an active ingredient of the most widely used herbicide and it is believed to be less toxic than other pesticides. However, several recent studies showed its potential adverse health effects to humans as it may be an endocrine disruptor. This study focuses on the effects of pure glyphosate on estrogen receptors (ERs) mediated transcriptional activity and their expressions. Glyphosate exerted proliferative effects only in human hormone-dependent breast cancer, T47D cells, but not in hormone-independent breast cancer, MDA-MB231 cells, at 10?¹² to 10??M in estrogen withdrawal condition. The proliferative concentrations of glyphosate that induced the activation of estrogen response element (ERE) transcription activity were 5-13 fold of control in T47D-KBluc cells and this activation was inhibited by an estrogen antagonist, ICI 182780, indicating that the estrogenic activity of glyphosate was mediated via ERs. Furthermore, glyphosate also altered both ER? and ? expression. These results indicated that low and environmentally relevant concentrations of glyphosate possessed estrogenic activity. Glyphosate-based herbicides are widely used for soybean cultivation, and our results also found that there was an additive estrogenic effect between glyphosate and genistein, a phytoestrogen in soybeans. However, these additive effects of glyphosate contamination in soybeans need further animal study. PMID:23756170

Thongprakaisang, Siriporn; Thiantanawat, Apinya; Rangkadilok, Nuchanart; Suriyo, Tawit; Satayavivad, Jutamaad

2013-09-01

156

Kinin B2 receptor deletion and blockage ameliorates cisplatin-induced acute renal injury.  

PubMed

Cisplatin treatment has been adopted in some chemotherapies; however, this drug can induce acute kidney injury due its ability to negatively affect renal function, augment serum levels of creatinine and urea, increase the acute tubular necrosis score and up-regulate cytokines (e.g., IL-1? and TNF-?). The kinin B2 receptor has been associated with the inflammation process, as well as the regulation of cytokine expression, and its deletion resulted in an improvement in the diabetic nephropathy status. To examine the role of the kinin B2 receptor in cisplatin-induced acute kidney injury, kinin B2 receptor knockout mice were challenged with cisplatin. Additionally, WT mice were treated with a B2 receptor antagonist after cisplatin administration. B2 receptor-deficient mice were less sensitive to this drug than the WT mice, as shown by reduced weight loss, better preservation of kidney function, down regulation of inflammatory cytokines and less acute tubular necrosis. Moreover, treatment with the kinin B2 receptor antagonist effectively reduced the levels of serum creatinine and blood urea after cisplatin administration. Thus, our data suggest that the kinin B2 receptor is involved in cisplatin-induced acute kidney injury by mediating the necrotic process and the expression of inflammatory cytokines, thus resulting in declined renal function. These results highlight the kinin B2 receptor antagonist treatment in amelioration of nephrotoxicity induced by cisplatin therapy. PMID:24975837

Estrela, Gabriel R; Wasinski, Frederick; Bacurau, Reury F; Malheiros, Denise M A C; Câmara, Niels O S; Araújo, Ronaldo C

2014-09-01

157

Effects of AT1 receptor antagonist, losartan, on rat hepatic fibrosis induced by CCl4  

Microsoft Academic Search

AIM To investigate effect o f losartan, an AT1 receptor antagonist, on hepatic fibrosis induced by CCl4; and to determine whether or not AT1 receptors are expressed on hepatic stellate cells. METHODS AND RESULTS Fifty male Sprague- Dawley rats, weighing (180 ± 20) g, were randomized into five groups (control group, model group, and three los artan treated groups), in

Hong Shan Wei; Ding Guo Li; Han Ming Lu; Yu Tao Zhan; Zhi Rong Wang; Xin Huang; Jing Zhang; Lin Cheng; Qin Fang Xu

2000-01-01

158

Sigma Receptor Antagonists Inhibit Human Lens Cell Growth and Induce Pigmentation  

Microsoft Academic Search

PURPOSE. The expression of the Sigma 1 receptor and the ability of receptor antagonists to inhibit growth and induce pigment formation were investigated in human lens epithelial cells. METHODS. Capsular bags were formed for experimental pur- poses by performing sham cataract operations on donor lenses. The resultant bags were cultured in Eagle's minimum essential medium (EMEM) alone or supplemented with

Lixin Wang; Alan R. Prescott; Barbara A. Spruce; Julie Sanderson; George Duncan

2005-01-01

159

Adaptation-induced Changes in Sensitivity in Frog Olfactory Receptor Cells  

Microsoft Academic Search

The suction pipette technique was used to study simultaneously the odour-induced action potential and receptor current responses in frog olfactory receptor cells, which were exposed to the odour cineole for 1 s by rapidly exchanging the solution bathing their cilia. The frequency of action potential firing increased as the odour concentration was raised and saturated within a 15-fold elevation above

Johannes Reisert; H. R. Matthews

2000-01-01

160

Thyroid Hormone Is an Inhibitor of Estrogen-Induced Degradation of Estrogen Receptor-Protein: Estrogen-  

E-print Network

Thyroid Hormone Is an Inhibitor of Estrogen-Induced Degradation of Estrogen Receptor- Protein in the control of receptor transcriptional activation function. Herein, we report that thyroid hormone can of the pituitary. The stabilization of ER pro- tein by thyroid hormone represents a selective blockade against

Alarid, Elaine T.

161

Toward a Consensus on the Operation of Receptor-Induced Calcium Entry Signals  

NSDL National Science Digital Library

Receptor-induced Ca2+ signals involve both Ca2+ release from intracellular stores and extracellular Ca2+ entry across the plasma membrane. The channels mediating Ca2+ entry and the mechanisms controlling their function remain largely a mystery. Here we critically assess current views on the Ca2+ entry process and consider certain modifications to the widely held hypothesis that Ca2+ store emptying is the fundamental trigger for receptor-induced Ca2+ entry channels. Under physiological conditions, receptor-induced store depletion may be quite limited. A number of distinct channel activities appear to mediate receptor-induced Ca2+ entry, and their activation is observed to occur through quite diverse coupling processes.

Donald L. Gill (University of Maryland School of Medicine; Department of Biochemistry and Molecular Biology REV)

2004-07-27

162

A Cre-inducible diphtheria toxin receptor mediates cell lineage ablation after toxin administration  

E-print Network

A Cre-inducible diphtheria toxin receptor mediates cell lineage ablation after toxin administration in oligodendrocytes, we observed myelin loss after intraperitoneal DT injections. Thus, DT crosses the blood

Cai, Long

163

A Role for the Acetylcholine Receptor-Inducing Protein ARIA in Oligodendrocyte Development  

Microsoft Academic Search

ARIA acetylcholine receptor-inducing activity protein, is a member of a family of ligands that includes the Neu differentiation factor, heregulin, and glial growth factor. These ligands all act through one or more receptor tyrosine kinases of ≈185 kDa. In some conditions these ligands promote proliferation, whereas in others they induce differentiation. ARIA was originally isolated from chick brain on the

Timothy Vartanian; Gabriel Corfas; You Li; Gerald D. Fischbach; Kari Stefansson

1994-01-01

164

Endothelin subtype A receptor antagonist induces osteopenia in growing rats  

Microsoft Academic Search

Previous studies suggested that endothelin (ET) peptides are involved in bone metabolism. We examined the effects of long-term blockade of the ETA receptor, a receptor subtype primarily involved in the anabolic actions of ET, on bone mineral status in growing rats. Eight-week-old rats injected intraperitoneally with FR139317 50 mg\\/kg body weight, a specific ETA receptor antagonist, for 2 or 4

Hirokazu Tsukahara; Chikahide Hori; Masahiro Hiraoka; Kazutaka Yamamoto; Yasushi Ishii; Mitsufumi Mayumi

1998-01-01

165

Estrogen stimuli promote osteoblastic differentiation via the subtilisin-like proprotein convertase PACE4 in MC3T3-E1 cells.  

PubMed

Estrogenic compounds include endogenous estrogens such as estradiol as well as soybean isoflavones, such as daidzein and its metabolite equol, which are known phytoestrogens that prevent osteoporosis in postmenopausal women. Indeed, mineralization of MC3T3-E1 cells, a murine osteoblastic cell line, was significantly decreased in medium containing fetal bovine serum treated with charcoal-dextran to deplete endogenous estrogens, but estradiol and these soybean isoflavones dose-dependently restored the differentiation of MC3T3-E1 cells; equol was tenfold more effective than daidzein. These differentiation-promoting effects were inhibited by the addition of fulvestrant, which is a selective downregulator of estrogen receptors. Analysis of the expression pattern of bone-related genes by reverse transcription PCR (RT-PCR)/quantitative real-time PCR (qRT-PCR), which focused on responsiveness to the estrogen stimuli, revealed that the transcription of PACE4, a subtilisin-like proprotein convertase, was tightly linked with the differentiation of MC3T3-E1 cells induced by estrogen stimuli. Moreover, treatment with RNAi of PACE4 in MC3T3-E1 cells resulted in a drastic decrease of mineralization in the presence of estrogen stimuli. These results strongly suggest that PACE4 participates in bone formation at least in osteoblast differentiation, and estrogen receptor-mediated stimuli induce osteoblast differentiation through the upregulation of PACE4 expression. PMID:24557631

Kim, Hyejin; Tabata, Atsushi; Tomoyasu, Toshifumi; Ueno, Tomomi; Uchiyama, Shigeto; Yuasa, Keizo; Tsuji, Akihiko; Nagamune, Hideaki

2015-01-01

166

Roles of ?-Opioid Receptors and Nociceptin/Orphanin FQ Peptide Receptors in Buprenorphine-Induced Physiological Responses in Primates  

PubMed Central

Buprenorphine is known as a ?-opioid peptide (MOP) receptor agonist, but its antinociception is compromised by the activation of nociceptin/orphanin FQ peptide (NOP) receptors in rodents. The aim of this study was to investigate the roles of MOP and NOP receptors in regulating buprenorphine-induced physiological responses in primates (rhesus monkeys). The effects of MOP antagonist (naltrexone), NOP antagonist [(±)-1-[(3R*,4R*)-1-(cyclooctylmethyl)-3-(hydroxymethyl)-4-piperidinyl]-3-ethyl-1,3-dihydro-2H-benzimidazol-2-one (J-113397)], and NOP agonists [(1S,3aS)-8-(2,3,3a,4,5,6-hexahydro-1H-phenalen-1-yl)-1-phenyl-1,3,8-triaza-spiro[4.5] decan-4-one (Ro 64-6198) and 3-endo-8-[bis(2-methylphenyl)methyl]-3-phenyl-8-azabicyclo[3.2.1]octan-3-ol (SCH 221510)] on buprenorphine were studied in three functional assays for measuring analgesia, respiratory depression, and itch in primates. Over the dose range of 0.01 to 0.1 mg/kg, buprenorphine dose-dependently produced antinociception, respiratory depression, and itch/scratching responses, and there was a ceiling effect at higher doses (0.1–1 mg/kg). Naltrexone (0.03 mg/kg) produced similar degrees of rightward shifts of buprenorphine's dose-response curves for all three endpoints. Mean pKB values of naltrexone (8.1–8.3) confirmed that MOP receptors mediated mainly buprenorphine-induced antinociception, respiratory depression, and itch/scratching. In contrast, J-113397 (0.1 mg/kg) did not change buprenorphine-induced physiological responses, indicating that there were no functional NOP receptors in buprenorphine-induced effects. More importantly, both NOP agonists, Ro 64-6198 and SCH 221510, enhanced buprenorphine-induced antinociception without respiratory depression and itch/ scratching. The dose-addition analysis revealed that buprenorphine in combination with the NOP agonist synergistically produced antinociceptive effects. These findings provided functional evidence that the activation of NOP receptors did not attenuate buprenorphine-induced antinociception in primates; instead, the coactivation of MOP and NOP receptors produced synergistic antinociception without other side effects. This study strongly supports the therapeutic potential of mixed MOP/NOP agonists as innovative analgesics. PMID:22743574

Cremeans, Colette M.; Gruley, Erin; Kyle, Donald J.

2012-01-01

167

Roles of ?-opioid receptors and nociceptin/orphanin FQ peptide receptors in buprenorphine-induced physiological responses in primates.  

PubMed

Buprenorphine is known as a ?-opioid peptide (MOP) receptor agonist, but its antinociception is compromised by the activation of nociceptin/orphanin FQ peptide (NOP) receptors in rodents. The aim of this study was to investigate the roles of MOP and NOP receptors in regulating buprenorphine-induced physiological responses in primates (rhesus monkeys). The effects of MOP antagonist (naltrexone), NOP antagonist [(±)-1-[(3R*,4R*)-1-(cyclooctylmethyl)-3-(hydroxymethyl)-4-piperidinyl]-3-ethyl-1,3-dihydro-2H-benzimidazol-2-one (J-113397)], and NOP agonists [(1S,3aS)-8-(2,3,3a,4,5,6-hexahydro-1H-phenalen-1-yl)-1-phenyl-1,3,8-triaza-spiro[4.5] decan-4-one (Ro 64-6198) and 3-endo-8-[bis(2-methylphenyl)methyl]-3-phenyl-8-azabicyclo[3.2.1]octan-3-ol (SCH 221510)] on buprenorphine were studied in three functional assays for measuring analgesia, respiratory depression, and itch in primates. Over the dose range of 0.01 to 0.1 mg/kg, buprenorphine dose-dependently produced antinociception, respiratory depression, and itch/scratching responses, and there was a ceiling effect at higher doses (0.1-1 mg/kg). Naltrexone (0.03 mg/kg) produced similar degrees of rightward shifts of buprenorphine's dose-response curves for all three endpoints. Mean pK(B) values of naltrexone (8.1-8.3) confirmed that MOP receptors mediated mainly buprenorphine-induced antinociception, respiratory depression, and itch/scratching. In contrast, J-113397 (0.1 mg/kg) did not change buprenorphine-induced physiological responses, indicating that there were no functional NOP receptors in buprenorphine-induced effects. More importantly, both NOP agonists, Ro 64-6198 and SCH 221510, enhanced buprenorphine-induced antinociception without respiratory depression and itch/ scratching. The dose-addition analysis revealed that buprenorphine in combination with the NOP agonist synergistically produced antinociceptive effects. These findings provided functional evidence that the activation of NOP receptors did not attenuate buprenorphine-induced antinociception in primates; instead, the coactivation of MOP and NOP receptors produced synergistic antinociception without other side effects. This study strongly supports the therapeutic potential of mixed MOP/NOP agonists as innovative analgesics. PMID:22743574

Cremeans, Colette M; Gruley, Erin; Kyle, Donald J; Ko, Mei-Chuan

2012-10-01

168

Genistein inhibits the proliferation and differentiation of MCF-7 and 3T3-L1 cells via the regulation of ER? expression and induction of apoptosis  

PubMed Central

The present study investigated the effect of the phytochemical genistein on the proliferation and differentiation of MCF-7 and 3T3-L1 cells via the regulation of estrogen receptor-? (ER?) expression and the induction of apoptosis. When MCF-7 human breast cancer cells were treated with 50, 100, 150 and 200 ?M genistein for 24, 48 or 72 h, cell growth was significantly decreased in a concentration-dependent manner. Notably, the patterns of ER? expression and proliferation in MCF-7 cells treated with genistein were similar. Furthermore, ER? expression in differentiating 3T3-L1 cells was significantly inhibited by 48 h treatment with 50 ?M genistein, which was selected based on the results of cytotoxicity assays on 3T3-L1 preadipocytes [lactate dehydrogenase (LDH) and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) viability assays]. Under the same conditions, genistein-induced apoptotic features were observed in MCF-7 and differentiating 3T3-L1 cells. This observation is supported by the finding that B-cell lymphoma 2 (Bcl-2) expression was reduced while that of Bcl-2-associated X protein (Bax) was induced by genistein. The results of the present study suggest that an ER?-related pathway and the induction of apoptosis are involved in the proliferation of MCF-7 cells and the differentiation of 3T3-L1 cells. PMID:25009600

CHOI, EUN JEONG; JUNG, JAE YEON; KIM, GUN-HEE

2014-01-01

169

Roles of parathyroid hormone (PTH) receptor and reactive oxygen species in hyperlipidemia-induced PTH resistance in preosteoblasts.  

PubMed

Bioactive lipids initiate inflammatory reactions leading to pathogenesis of atherosclerosis. Evidence shows that they also contribute to bone loss by inhibiting parathyroid hormone receptor (PTH1R) expression and differentiation of osteoblasts. We previously demonstrated that bone anabolic effects of PTH(1-34) are blunted in hyperlipidemic mice and that these PTH effects are restored by antioxidants. However, it is not clear which osteoblastic cell developmental stage is targeted by bioactive lipids. To investigate the effects of hyperlipidemia at the cellular level, hyperlipidemic Ldlr(-/-) mice were bred with Col3.6GFPtpz mice, in which preosteoblasts/osteoblasts carry a topaz fluorescent label, and with Col2.3GFPcyan mice, in which more mature osteoblasts/osteocytes carry a cyan fluorescent label. Histological analyses of trabecular bone surfaces in femoral as well as calvarial bones showed that intermittent PTH(1-34) increased fluorescence intensity in WT-Tpz mice, but not in Tpz-Ldlr(-/-) mice. In contrast, PTH(1-34) did not alter fluorescence intensity in femoral cortical envelopes of either WT-Cyan or Ldlr(-/-)-Cyan mice. To test the mechanism of PTH1R downregulation, preosteoblastic MC3T3-E1 cells were treated with bioactive lipids and the antioxidant Trolox. Results showed that inhibitory effects of PTH1R levels by bioactive lipids were rescued by pretreatment with Trolox. The inhibitory effects on expression of PTH1R as well as on PTH-induced osteoblastic genes were mimicked by xanthine/xanthine oxidase, a known generator of reactive oxygen species. These findings suggest an important role of the preosteoblastic development stage as the target and downregulation of PTH receptor expression mediated by intracellular oxidant stress as a mechanism in hyperlipidemia-induced PTH resistance. PMID:24038594

Li, Xin; Garcia, Jamie; Lu, Jinxiu; Iriana, Sidney; Kalajzic, Ivo; Rowe, David; Demer, Linda L; Tintut, Yin

2014-01-01

170

Pathways and receptors involved in peptide YY induced contraction of rat proximal colonic muscle in vitro  

PubMed Central

BACKGROUND—Peptide YY (PYY) is involved in the regulation of several gut functions, including secretion and motility. It exerts its effects through a family of six receptors, commonly named the Y receptor family.?AIMS—To characterise the effects of PYY on strips of rat proximal colon in vitro, and to determine the pathways and receptors involved.?METHODS—Contractions of strips removed from the muscle layer of rat proximal colon were recorded under isometric conditions, using PYY, Y receptor agonists and antagonists, and nerve blockers. Reverse transcription-polymerase chain reaction was also performed to detect the presence of mRNA coding for Y receptors. Finally, smooth muscle cells were isolated to estimate the cell length and intracellular Ca2+ concentration in the presence and absence of PYY.?RESULTS—PYY, neuropeptide Y (NPY), pancreatic polypeptide (PP) and [Leu31,Pro34]NPY induced a dose dependent contraction of strips from proximal colon. Tetrodotoxin partially inhibited the PYY and NPY induced contractions, and strongly inhibited the PP induced contraction. Specific antagonists showed the involvement of cholinergic nicotinic receptors and NK1 receptor. BIBP 3226, a specific Y1 antagonist, did not modify the colonic smooth muscle response to PYY, whereas blocking L-type Ca2+ channels with D-600 abolished its effects. Moreover, PYY induced an increase in intracellular Ca2+ concentration, associated with a reduction in cell length. mRNA encoding Y1 and Y4 receptors were detected in the muscle strips.?CONCLUSIONS—These findings suggest that PYY stimulates colonic contractile activity in vitro through (a) a nervous Y4 dependent pathway and (b) a pathway involving a potential new receptor on myocytes.???Keywords: peptide YY; Y receptors; colon; motility; myocytes PMID:10673299

Ferrier, L; Segain, J; Pacaud, P; Cherbut, C; Loirand, G; Galmiche, J; Blottiere, H

2000-01-01

171

TRPC Channels Mediate a Muscarinic Receptor-Induced Afterdepolarization in Cerebral Cortex  

PubMed Central

Activation of muscarinic cholinergic receptors on pyramidal cells of the cerebral cortex induces the appearance of a slow afterdepolarization that can sustain autonomous spiking after a brief excitatory stimulus. Accordingly, this phenomenon has been hypothesized to allow for the transient storage of memory traces in neuronal networks. Here we investigated the molecular basis underlying the muscarinic receptor-induced afterdepolarization using molecular biological and electrophysiological strategies. We find that the ability of muscarinic receptors to induce the inward aftercurrent underlying the slow afterdepolarization is inhibited by expression of a G?q-11 dominant negative and is also markedly reduced in a phospholipase C ?1 (PLC?1) knock-out mouse. Furthermore, we show, using a genetically encoded biosensor, that activation of muscarinic receptor induces the breakdown of phosphatidylinositol 4,5-bisphosphate in pyramidal cells. These results indicate that the G?q-11/PLC?1 cascade plays a key role in the ability of muscarinic receptors to signal the inward aftercurrent. We have shown previously that the muscarinic afterdepolarization is mediated by a calcium-activated nonselective cation current, suggesting the possible involvement of TRPC channels. We find that expression of a TRPC dominant negative inhibits, and overexpression of wild-type TRPC5 or TRPC6 enhances, the amplitude of the muscarinic receptor-induced inward aftercurrent. Furthermore, we find that coexpression of TRPC5 and T-type calcium channels is sufficient to reconstitute a muscarinic receptor-activated inward aftercurrent in human embryonic kidney HEK-293 cells. These results indicate that TRPC channels mediate the muscarinic receptor-induced slow afterdepolarization seen in pyramidal cells of the cerebral cortex and suggest a possible role for TRPC channels in mnemonic processes. PMID:19675237

Yan, Hai-Dun; Villalobos, Claudio; Andrade, Rodrigo

2009-01-01

172

Muscle hyperalgesia induced by peripheral P2X3 receptors is modulated by inflammatory mediators.  

PubMed

ATP, via activation of P2X3 receptors, has been highlighted as a key target in inflammatory hyperalgesia. Therefore, the aim of this study was to confirm whether the activation of P2X3 receptors in the gastrocnemius muscle of rats induces mechanical muscle hyperalgesia and, if so, to analyze the involvement of the classical inflammatory mediators (bradykinin, prostaglandins, sympathetic amines, pro-inflammatory cytokines and neutrophil migration) in this response. Intramuscular administration of the non-selective P2X3 receptor agonist ?,?-meATP in the gastrocnemius muscle of rats induced mechanical muscle hyperalgesia, which, in turn, was prevented by the selective P2X3 and P2X2/3 receptors antagonist A-317491, the selective bradykinin B1-receptor antagonist Des-Arg9-[Leu8]-BK (DALBK), the cyclooxygenase inhibitor indomethacin, the ?1- or ?2-adrenoceptor antagonist atenolol and ICI 118,551, respectively. Also, the nonspecific selectin inhibitor fucoidan. ?,?-meATP induced increases in the local concentration of the pro-inflammatory cytokines tumor necrosis factor-? (TNF-?) and interleukin 1? (IL-1?), which were reduced by bradykinin antagonist. Finally, ?,?-meATP also induced neutrophil migration. Together, these findings suggest that ?,?-meATP induced mechanical hyperalgesia in the gastrocnemius muscle of rats via activation of peripheral P2X3 receptors, which involves bradykinin, prostaglandins, sympathetic amines, pro-inflammatory cytokines release and neutrophil migration. It is also indicated that bradykinin is the key modulator of the mechanical muscle hyperalgesia induced by P2X3 receptors. Therefore, we suggest that P2X3 receptors are important targets to control muscle inflammatory pain. PMID:25446353

Schiavuzzo, J G; Teixeira, J M; Melo, B; da Silva Dos Santos, D F; Jorge, C O; Oliveira-Fusaro, M C G; Parada, C A

2015-01-29

173

Regulation of angiotensin II receptors levels during rat induced pulpitis.  

PubMed

A change in the microcirculatory hemodynamic is one of the most important events in inflammation. In the dental pulp, which is a connective tissue surrounded by a mineralized dentine substrate, disturbance in the blood flow as well as plasma extravasation may increase the pulp pressure and cause local ischemia. The octapeptide angiotensin II (AngII) regulates vascular tone and stimulates the release of pro-inflammatory cytokines by acting through the AT1 and AT2 receptors. The AT1 receptor is responsible for the classical effects of AngII. The AT2 receptor is involved in other effects, such as vasodilation. Therefore, we aimed to evaluate the role of AT1 and AT2 receptors on the pulpal inflammation. The pulp tissue was mechanically exposed and after different periods the teeth were extracted and submitted to histopathological and RT-PCR analyses. The histological sections showed a number of congested and dilated blood vessels associated with a notable presence of inflammatory cells. RT-PCR data revealed that the AT1 receptor was down-regulated at 24 h after the pulp exposure. The AT2 receptor expression was up-regulated by a 9-hour period, and then decreased between 12- and 24-hour periods. It was demonstrated that the renin-angiotensin system plays an important role in the pulpal inflammation, with regulation of AngII receptor levels. PMID:17197045

Souza, Pedro P C; Fukada, Sandra Y; Cunha, Fernando Q; Costa, Carlos A S; Costa-Neto, Claudio M

2007-04-01

174

Sigma1 receptor antagonists determine the behavioral pattern of the methamphetamine-induced stereotypy in mice  

PubMed Central

Objective The effects of sigma receptor antagonists on methamphetamine (METH)-induced stereotypy have not been examined. We examined the effects of sigma antagonists on METH-induced stereotypy in mice. Results The administration of METH (10 mg/kg) to male ddY mice induced stereotyped behavior consisting of biting (90.1%), sniffing (4.2%), head bobbing (4.1%), and circling (1.7%) during an observation period of 1 h. Pretreatment of the mice with BMY 14802 (?-(4-fluorophenyl)-4-(5-fluoro-2-pyrimidinyl)-1-piperazinebutanol; 1, 5, and 10 mg/kg), a non-specific sigma receptor antagonist, significantly increased METH-induced sniffing (19.2, 30.5, and 43.8% of total stereotypical behavior) but decreased biting (76.6, 66.9, and 49.3% of total stereotypical behavior) in a dose-dependent manner. This response was completely abolished by (+)-SKF 10,047 ([2S-(2?,6?,11R)]-1,2,3,4,5,6-hexahydro-6,11-dimethyl-3-(2-propenyl)-2,6-methano-3-benzazocin-8-ol; 4 and 10 mg/kg), a putative sigma1 receptor agonist, and partially by PB 28 (1-cyclohexyl-4-[3-(1,2,3,4-tetrahydro-5-methoxy-1-naphthalen-1-yl)-n-propyl]piperazine; 1 and 10 mg/kg), a putative sigma2 receptor agonist. The BMY 14802 action on METH-induced stereotypy was mimicked by BD 1047 (N-[2-(3,4-dichlorophenyl)ethyl]-N-methyl-2-(dimethylamino)ethylamine; 10 mg/kg), a putative sigma1 receptor antagonist, but not by SM-21 ((±)-tropanyl 2-(4-chlorophenoxy)butanoate; 1 mg/kg), a putative sigma2 receptor antagonist. The BD 1047 effect on METH-induced stereotypy was also abolished completely by (+)-SKF 10,047 and partially by PB 28. The overall frequency of METH-induced stereotypical behavior was unchanged with these sigma receptor ligands, despite the alteration in particular behavioral patterns. The BMY 14802 action on METH-induced stereotypy was unaffected by pretreatment with centrally acting histamine H1 receptor antagonists (pyrilamine or ketotifen, 10 mg/kg), suggesting that these effects are independent of histamine H1 receptor signaling systems. Conclusion In summary, modulation of central sigma1 receptors alters the pattern of METH-induced stereotypy, producing a shift from stereotypical biting to stereotypical sniffing, without affecting the overall frequency of stereotypical behavior. PMID:19052726

Kitanaka, J.; Kitanaka, N.; Tatsuta, T.; Hall, F.S.; Uhl, G.R.; Tanaka, K.; Nishiyama, N.; Morita, Y.; Takemura, M.

2011-01-01

175

Peripheral P2X7 receptor-induced mechanical hyperalgesia is mediated by bradykinin.  

PubMed

P2X7 receptors play an important role in inflammatory hyperalgesia, but the mechanisms involved in their hyperalgesic role are not completely understood. In this study, we hypothesized that P2X7 receptor activation induces mechanical hyperalgesia via the inflammatory mediators bradykinin, sympathomimetic amines, prostaglandin E2 (PGE2), and pro-inflammatory cytokines and via neutrophil migration in rats. We found that 2'(3')-O-(4-benzoylbenzoyl)adenosine 5'-triphosphate triethylammonium salt (BzATP), the most potent P2X7 receptor agonist available, induced a dose-dependent mechanical hyperalgesia that was blocked by the P2X7 receptor-selective antagonist A-438079 but unaffected by the P2X1,3,2/3 receptor antagonist TNP-ATP. These findings confirm that, although BzATP also acts at both P2X1 and P2X3 receptors, BzATP-induced hyperalgesia was mediated only by P2X7 receptor activation. Co-administration of selective antagonists of bradykinin B1 (Des-Arg(8)-Leu(9)-BK (DALBK)) or B2 receptors (bradyzide), ?1 (atenolol) or ?2 adrenoceptors (ICI 118,551), or local pre-treatment with the cyclooxygenase inhibitor indomethacin or the nonspecific selectin inhibitor fucoidan each significantly reduced BzATP-induced mechanical hyperalgesia in the rat hind paw. BzATP also induced the release of the pro-inflammatory cytokines tumor necrosis factor ? (TNF-?), interleukin (IL)-1?, IL-6 and cytokine-induced neutrophil chemoattractant-1 (CINC-1), an effect that was significantly reduced by A-438079. Co-administration of DALBK or bradyzide with BzATP significantly reduced BzATP-induced IL-1? and CINC-1 release. These results indicate that peripheral P2X7 receptor activation induces mechanical hyperalgesia via inflammatory mediators, especially bradykinin, which may contribute to pro-inflammatory cytokine release. These pro-inflammatory cytokines in turn may mediate the contributions of PGE2, sympathomimetic amines and neutrophil migration to the mechanical hyperalgesia induced by local P2X7 receptor activation. PMID:24997266

Teixeira, J M; de Oliveira-Fusaro, M C G; Parada, C A; Tambeli, C H

2014-09-26

176

Mitochondrial function is required for hydrogen peroxide-induced growth factor receptor transactivation and downstream signaling.  

PubMed

The transactivation of growth factor receptors is an early event in H(2)O(2)-induced signaling, although proximal targets in this process remain unclear. We found that inhibition of flavin- or heme-containing proteins eliminated H(2)O(2)-induced transactivation of the epidermal growth factor receptor and stimulation of its downstream targets, JNK and Akt. Inhibition of mitochondrial function with rotenone, antimycin A, KCN, carbonylcyanide-m-chlorophenylhydrazone, or oligomycin reproduced this effect, as did generation of mitochondrial DNA-deficient (pseudo-rho(0)) cells. Mitochondrial function had no role in JNK activation in response to UV irradiation or tumor necrosis factor-alpha. The impact of mitochondrial function on H(2)O(2)-induced growth factor transactivation was ubiquitous and applied to both the vascular endothelial growth factor (VEGF)-2 receptor and the platelet-derived growth factor-beta receptor in endothelium and fibroblasts, respectively. In contrast, ligand-induced growth factor activation was unrelated to mitochondrial function. Growth factor receptor transactivation and its downstream signaling in response to H(2)O(2) appeared to involve redox-sensitive mitochondrial events as they were abrogated by a mitochondrial-targeted antioxidants but not their nontargeted counterparts. Functionally, we found that mitochondrial-targeted antioxidants inhibited H(2)O(2)-induced apoptosis and cell death but had no effect with UV irradiation. These data establish a novel role for the mitochondrion as a proximal target specific to H(2)O(2)-induced signaling and growth factor transactivation. PMID:15180991

Chen, Kai; Thomas, Shane R; Albano, Adam; Murphy, Michael P; Keaney, John F

2004-08-13

177

Central mineralocorticoid receptors are indispensable for corticosterone-induced impairment of memory retrieval in rats  

Microsoft Academic Search

Previous studies indicated that stress levels of glucocorticoid hormones (cortisol in humans, and corticosterone in rodents) induce impairment of long-term memory retrieval, but the underlying mechanisms (genomic or nongenomic) are not clear. To clarify this issue, we investigated the involvement of brain corticosteroid receptors and protein synthesis in the corticosterone-induced impairment of memory retrieval. Young rats were trained in the

M. Khaksari; A. Rashidy-Pour; A. A. Vafaei

2007-01-01

178

Localization of type I interferon receptor limits interferon-induced TLR-3 in epithelial cells  

EPA Science Inventory

This study aimed to expand on the role of type I IFNs in the influenza-induced upregulation of TLR3 and determine whether and how the localization of the IFN-alpha/beta receptor (IFNAR) in respiratory epithelial cells could modify IFN-induced responses. Using differentiated prima...

179

Dextromethorphan-induced psychotoxic behaviors cause sexual dysfunction in male mice via stimulation of ?-1 receptors.  

PubMed

Dextromethorphan (DM) is a well-known antitussive dextrorotatory morphinan. We and others have demonstrated that sigma (?) receptors may be important for DM-mediated neuromodulation. Because an earlier report suggested that DM might affect sexual function and that ? receptor ligands affect signaling pathways in the periphery, we examined whether DM-induced psychotoxic burden affected male reproductive function. We observed that DM had a high affinity at ?-1 receptors in the brain and testis but relatively low affinity at ?-2 receptors. Prolonged treatment with DM resulted in conditioned place preference and hyperlocomotion, followed by an increase in Fos-related antigen expression in the nucleus accumbens in male mice. Simultaneously, DM induced significant reductions in gonadotropin-releasing-hormone immunoreactivity in the hypothalamus. Moreover, we observed that DM induced increased sperm abnormalities and decreased sperm viability and sexual behavior. These phenomena were significantly attenuated by combined treatment with BD1047, a ?-1 receptor antagonist, but not by SM-21, a ?-2 receptor antagonist. Thus, these results suggest that DM psychotoxicity might lead to reproductive stress in male mice by activating ?-1 receptors. PMID:22326744

Nam, Yunsung; Shin, Eun-Joo; Yang, Boo-Keun; Bach, Jae-Hyung; Jeong, Ji Hoon; Chung, Yoon Hee; Park, Eon Sub; Li, Zhengyi; Kim, Kee-Won; Kwon, Young-Bae; Nabeshima, Toshitaka; Kim, Hyoung-Chun

2012-11-01

180

alpha1B-Adrenergic receptor phosphorylation and desensitization induced by transforming growth factor-beta.  

PubMed Central

Transforming growth factor-beta (TGF-beta) induced alpha(1B)-adrenergic receptor phosphorylation in Rat-1 fibroblasts stably expressing these adrenoceptors. This effect of TGF-beta was rapid, reaching a maximum within 30 min and decreasing thereafter, and concentration-dependent (EC(50) 0.3 pM). The phosphoinositide 3-kinase inhibitors wortmannin and LY294002, and the protein kinase C inhibitors staurosporine, Ro 318220 and bisindolylmaleimide, blocked the effect of this growth factor. alpha(1B)-Adrenergic receptor phosphorylation was associated with desensitization, as indicated by a reduction in the adrenergic-mediated production of [(3)H]inositol phosphates. Phosphorylation of alpha(1B)-adrenergic receptors by TGF-beta was also observed in Cos-1 cells transfected with the receptor. Co-transfection of the dominant-negative mutant of the regulatory subunit of phosphoinositide 3-kinase (Deltap85) inhibited the phosphorylation of alpha(1B)-adrenergic receptors induced by TGF-beta. Our results indicate that activation of TGF-beta receptors induces alpha(1B)-adrenergic receptor phosphorylation and desensitization. The data suggest that phosphoinositide 3-kinase and protein kinase C play key roles in this effect of TGF-beta. PMID:12234252

Romero-Avila, M Teresa; Flores-Jasso, C Fabián; García-Sáinz, J Adolfo

2002-01-01

181

Gamma-hydroxybutyrate (GHB) induces cognitive deficits and affects GABAB receptors and IGF-1 receptors in male rats.  

PubMed

In recent years, the abuse of the club drug gamma-hydroxybutyrate (GHB) has become increasingly popular among adolescents. The drug induces euphoria but can also result in sedation, anaesthesia as well as short-term amnesia. In addition, the abuse of GHB causes cognitive impairments and the mechanism by which GHB induces these impairments is not clarified. The present study investigates the impact of GHB treatment on spatial learning and memory using a water maze (WM) test in rats. Furthermore, the behavioural data is combined with an autoradiographic analysis of the GABAB and the IGF-1 receptor systems. The results demonstrate that the animals administered with GHB display an impaired performance in the WM test as compared to controls. In addition, significant alterations in GABAB and IGF-1 receptor density as well as GABAB receptor functionality, were observed in several brain regions associated with cognitive functions e.g. hippocampus. To conclude, our findings suggest that GHB treatment can affect spatial learning and memory, and that this outcome at least to some extent is likely to involve both GABAB and IGF-1 receptors. PMID:24786330

Johansson, Jenny; Grönbladh, Alfhild; Hallberg, Mathias

2014-08-01

182

How one TSH receptor antibody induces thyrocyte proliferation while another induces apoptosis.  

PubMed

Thyroid stimulating hormone (TSH) activates two major G-protein arms, Gs? and Gq leading to initiation of down-stream signaling cascades for survival, proliferation and production of thyroid hormones. Antibodies to the TSH receptor (TSHR-Abs), found in patients with Graves' disease, may have stimulating, blocking, or neutral actions on the thyroid cell. We have shown previously that such TSHR-Abs are distinct signaling imprints after binding to the TSHR and that such events can have variable functional consequences for the cell. In particular, there is a great contrast between stimulating (S) TSHR-Abs, which induce thyroid hormone synthesis and secretion as well as thyroid cell proliferation, compared to so called "neutral" (N) TSHR-Abs which may induce thyroid cell apoptosis via reactive oxygen species (ROS) generation. In the present study, using a rat thyrocyte (FRTL-5) ex vivo model system, our hypothesis was that while N-TSHR-Abs can induce apoptosis via activation of mitochondrial ROS (mROS), the S-TSHR-Abs are able to stimulate cell survival and avoid apoptosis by actively suppressing mROS. Using fluorescent microscopy, fluorometry, live cell imaging, immunohistochemistry and immunoblot assays, we have observed that S-TSHR-Abs do indeed suppress mROS and cellular stress and this suppression is exerted via activation of the PKA/CREB and AKT/mTOR/S6K signaling cascades. Activation of these signaling cascades, with the suppression of mROS, initiated cell proliferation. In sharp contrast, a failure to activate these signaling cascades with increased activation of mROS induced by N-TSHR-Abs resulted in thyroid cell apoptosis. Our current findings indicated that signaling diversity induced by different TSHR-Abs regulated thyroid cell fate. While S-TSHR-Abs may rescue cells from apoptosis and induce thyrocyte proliferation, N-TSHR-Abs aggravate the local inflammatory infiltrate within the thyroid gland, or in the retro-orbit, by inducing cellular apoptosis; a phenomenon known to activate innate and by-stander immune-reactivity via DNA release from the apoptotic cells. PMID:23958398

Morshed, Syed A; Ma, Risheng; Latif, Rauf; Davies, Terry F

2013-12-01

183

ROLES OF OPIOID RECEPTOR SUBTYPES IN MEDIATING ALCOHOL SEEKING INDUCED BY DISCRETE CUES AND CONTEXT  

PubMed Central

The aim of this study was to assess the effects of selective blockade of the delta (DOP) or mu opioid (MOP) receptors on alcohol seeking induced by discrete cues and context. In Experiment 1, rats were trained to self-administer alcohol in an environment with distinct sensory properties. After extinction in a different context with separate sensory properties, rats were tested for context-induced renewal in the original context following treatment with the DOP receptor antagonist naltrindole (0 – 15-mg/kg, IP) or the MOP receptor antagonist CTOP (0 – 3-µg/kg ICV). In a separate set of experiments, reinstatement was tested with the presentation of a discrete light+tone cue previously associated with alcohol delivery, following extinction without the cue. In Experiment 2, the effects of naltrindole (0 – 5-mg/kg, IP) or CTOP (0 – 3-µg/kg µg ICV) were assessed. For context-induced renewal, 7.5-mg/kg naltrindole reduced responding without affecting locomotor activity. Both doses of CTOP attenuated responding in the first 15 min of the renewal test session; however, total responses did not differ at the end of the session. For discrete cue-induced reinstatement, 1 and 5-mg/kg naltrindole attenuated responding, but CTOP had no effect. We conclude that while DOP receptors mediate alcohol seeking induced by discrete cues and context, MOP receptors may play a modest role only in context-induced renewal. These findings point to a differential involvement of opioid receptor subtypes in the effects of different kinds of conditioned stimuli on alcohol seeking, and support a more prominent role for DOP receptors. PMID:19686472

Marinelli, Peter W.; Funk, Douglas; Harding, Stephen; Li, Zhaoxia; Juzytsch, Walter; Lê, A.D.

2009-01-01

184

The selective ? opioid receptor antagonist ?-funaltrexamine attenuates methamphetamine-induced stereotypical biting in mice.  

PubMed

We investigated whether pretreatment with opioid receptor antagonists affected methamphetamine (METH)-induced stereotypy in mice. Pretreatment of male ICR mice with naloxone, a relatively non-selective opioid receptor antagonist, significantly attenuated the total incidence of METH-induced stereotypical behavior compared with saline vehicle-pretreated subjects. Furthermore, the distribution of METH-induced stereotypical behavior was affected by naloxone administration. Thus, METH-induced stereotypical sniffing and persistent locomotion were significantly increased by naloxone treatment while stereotypical biting was reduced. One way to interpret this pattern of effects is that pretreatment with naloxone appeared to produce a shift in the dose-response curve for METH. Thus, while the more intense forms of oral-facial stereotypies were reduced, increased persistent locomotion was observed in mice given naloxone followed by METH. The selective ? opioid receptor antagonist ?-funaltrexamine, but not nor-binaltorphimine (a ?-selective antagonist) nor naltrindole (a ?-selective antagonist), mimicked the effect of naloxone. These observations suggest that opioid receptor antagonists may attenuate METH-induced stereotypical biting in mice via ? opioid receptors, and suggest that antagonism of this system may be a potential therapeutic approach to reducing some deleterious effects of METH use and perhaps in the treatment of some forms of self-injurious behavior. PMID:23727404

Kitanaka, Junichi; Kitanaka, Nobue; Hall, F Scott; Uhl, George R; Fukushima, Yuko; Sawai, Tatsuo; Watabe, Kaname; Kubo, Hitoshi; Takahashi, Hitoshi; Tanaka, Koh-Ichi; Nishiyama, Nobuyoshi; Tatsuta, Tomohiro; Morita, Yoshio; Takemura, Motohiko

2013-07-19

185

Retinoids enhance glucocorticoid-induced apoptosis of T cells by facilitating glucocorticoid receptor-mediated transcription  

PubMed Central

Glucocorticoid-induced apoptosis of thymocytes is one of the first recognized forms of programmed cell death. It was shown to require gene activation induced by the glucocorticoid receptor (GR) translocated into the nucleus following ligand binding. In addition, the necessity of the glucocorticoid-induced, but transcription-independent phosphorylation of phosphatidylinositol-specific phospholipase C (PI-PLC) has also been shown. Here we report that retinoic acids, physiological ligands for the nuclear retinoid receptors, enhance glucocorticoid-induced death of mouse thymocytes both in vitro and in vivo. The effect is mediated by retinoic acid receptor (RAR) alpha/retinoid X receptor (RXR) heterodimers, and occurs when both RAR? and RXR are ligated by retinoic acids. We show that the ligated RAR?/RXR interacts with the ligated GR, resulting in an enhanced transcriptional activity of the GR. The mechanism through which this interaction promotes GR-mediated transcription does not require DNA binding of the retinoid receptors and does not alter the phosphorylation status of Ser232, known to regulate the transcriptional activity of GR. Phosphorylation of PI-PLC was not affected. Besides thymocytes, retinoids also promoted glucocorticoid-induced apoptosis of various T-cell lines, suggesting that they could be used in the therapy of glucocorticoid-sensitive T-cell malignancies. PMID:21072052

Tóth, K; Sarang, Z; Scholtz, B; Brázda, P; Ghyselinck, N; Chambon, P; Fésüs, L; Szondy, Z

2011-01-01

186

Acetylcholine Receptor-Inducing Activity Stimulates Expression of the ?-Subunit Gene of the Muscle Acetylcholine Receptor  

Microsoft Academic Search

Motor neurons regulate the transcription of acetylcholine receptor subunit genes in postsynaptic muscle fibers both through muscle electrical activity produced by motor neuron acetylcholine release and by mechanisms independent of such transmitter release. Factors secreted by the motor neuron may mediate activity-independent regulation, including the postnatal switch from alpha_2betagammadelta (embryonic type) to alpha_2beta?delta (adult type) receptors. We have investigated the

Jean-Claude Martinou; Douglas L. Falls; Gerald D. Fischbach; John P. Merlie

1991-01-01

187

Suppression of Niacin-induced Vasodilation with an Antagonist to Prostaglandin D2 Receptor Subtype 1  

Microsoft Academic Search

Niacin (nicotinic acid) reduces cardiovascular events in patients with dyslipidemia. However, symptoms associated with niacin-induced vasodilation (e.g., flushing) have limited its use. Laropiprant is a selective antagonist of the prostaglandin D2 receptor subtype 1 (DP1), which may mediate niacin-induced vasodilation. The aim of this proof-of-concept study was to evaluate the effects of laropiprant (vs placebo) on niacin-induced cutaneous vasodilation. Coadministration

E Lai; I De Lepeleire; T M Crumley; F Liu; L A Wenning; N Michiels; E Vets; G O'Neill; J A Wagner; K Gottesdiener

2007-01-01

188

Oxytocin receptor ligands induce changes in cytoskeleton in neuroblastoma cells.  

PubMed

Aim of the present study was to evaluate effects of ligands of oxytocin receptors on gene expression of neurofilament proteins (nestin and microtubule-associated protein 2 (MAP2)) associated with neuronal differentiation and growth factors (brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF)) related to neuronal growth. Fluorescent staining of F-actin was used to observe morphology of cells. Co-treatment with oxytocin and oxytocin receptor antagonist--atosiban--resulted in significant increase of MAP2 gene expression in SK-N-SH cells. There was no effect of oxytocin on gene expression of growth factors BDNF and NGF. Surprisingly, oxytocin with atosiban significantly increased mRNA levels for both BDNF and NGF. Gene expression of vasopressin receptor (V1aR) significantly decreased in response to vasopressin. Atosiban decreased mRNA levels for oxytocin receptor (OXTR) and V1aR. Oxytocin significantly decreased OXTR and nestin mRNA levels and increased mRNA levels for BDNF and NGF in U-87 MG cells. The densest recruitment of F-actin filaments was observed in apical parts of filopodia in SK-N-SH cells incubated in oxytocin presence. Present data demonstrate complex role of ligands of oxytocin receptors in regulation of gene expression of intermediate filaments and thus, oxytocin might be considered as a growth factor in neuronal type of cells. PMID:23335033

Bakos, Jan; Strbak, Vladimir; Paulikova, Helena; Krajnakova, Lucia; Lestanova, Zuzana; Bacova, Zuzana

2013-07-01

189

NMDA receptor activation induces translocation and activation of Rac in mouse hippocampal area CA1  

PubMed Central

Neuronal development requires several discrete morphological steps that are believed to involve the small GTPase Rac. For example, neural activity, through NMDA receptors and/or AMPA receptors, activates Rac leading to elaboration of dendritic arbors. In the current study, we have conducted studies which indicate that Rac might be an important molecule involved in morphological plasticity in the adult mouse. We demonstrate that Rac is expressed at synapses in the adult mouse hippocampus. We also demonstrate that treatment of hippocampal slices with NMDA induces membrane translocation and activation of Rac in area CA1. Interestingly, we also find that there is an increase in Rac that is associated with NMDA receptor complexes following NMDA receptor activation. Taken together, our data are consistent with the idea that Rac could be participating in NMDA receptor-dependent changes in morphology that occur during synaptic plasticity and memory formation in the adult mouse hippocampus. PMID:16546126

Tejada-Simon, Maria V.; Villasana, Laura E.; Serrano, Faridis; Klann, Eric

2007-01-01

190

The Cytosolic Pattern Recognition Receptor NOD1 Induces Inflammatory Interleukin8 during Chlamydia trachomatis Infection  

Microsoft Academic Search

Inflammation is a hallmark of chlamydial infections, but how inflammatory cytokines are induced is not well understood. Pattern recognition receptors (PRR) of the host innate immune system recognize pathogen molecules and activate intracellular signaling pathways that modulate immune responses. The role of PRR such as Toll-like receptors (TLR) and nucleotide-binding oligomerization domain (NOD) proteins in the endogenous interleukin-8 (IL-8) response

Kerry R. Buchholz; Richard S. Stephens

2008-01-01

191

Endothelin receptors in kainic acid-induced neural lesions of rat brain  

Microsoft Academic Search

Seven days after an intracerebroventricular injection of 0.8?g kainic acid, a time of neural tissue-repair after damage, we applied our receptor autoradiographic method to examine changes in the endothelin receptors in kainic acid-induced neural lesions of the rat brain. There were belt-shaped areas with the de novo expressed [125I]endothelin-1 binding sites in the damaged hippocampus CA1, CA3, and CA4 subfields.

Y. Sakurai-Yamashita; M. Niwa; K. Yamashita; Y. Kataoka; A. Himeno; K. Shigematsu; K. Tsutsumi; K. Taniyama

1997-01-01

192

Agonists of proteinase-activated receptor 1 induce plasma extravasation by a neurogenic mechanism  

Microsoft Academic Search

1 Thrombin, generated in the circulation during injury, cleaves proteinase-activated receptor 1 (PAR1) to stimulate plasma extravasation and granulocyte infiltration. However, the mechanism of thrombin-induced inflammation in intact tissues is unknown. We hypothesized that thrombin cleaves PAR1 on sensory nerves to release substance P (SP), which interacts with the neurokinin 1 receptor (NK1R) on endothelial cells to cause plasma extravasation.

Lawrence de Garavilla; Nathalie Vergnolle; Steven H. Young; Helena Ennes; Martin Steinhoff; Valeria S Ossovskaya; Michael R D'Andrea; Emeran A Mayer; John L Wallace; Morley D Hollenberg; Patricia Andrade-Gordon; Nigel W Bunnett

2001-01-01

193

Tumor Necrosis Factor Receptor Family Member RANK Mediates Osteoclast Differentiation and Activation Induced by Osteoprotegerin Ligand  

Microsoft Academic Search

A receptor that mediates osteoprotegerin ligand (OPGL)-induced osteoclast differentiation and activation has been identified via genomic analysis of a primary osteoclast precursor cell cDNA library and is identical to the tumor necrosis factor receptor (TNFR) family member RANK. The RANK mRNA was highly expressed by isolated bone marrow-derived osteoclast progenitors and by mature osteoclasts in vivo. Recombinant OPGL binds specifically

Hailing Hsu; David L. Lacey; Colin R. Dunstan; Irina Solovyev; Anne Colombero; Emma Timms; Hong-Lin Tan; Gary Elliott; Michael J. Kelley; Ildiko Sarosi; Ling Wang; Xing-Zhong Xia; Robin Elliott; Laura Chiu; Tabitha Black; Sheila Scully; Casey Capparelli; Sean Morony; Grant Shimamoto; Michael B. Bass; William J. Boyle

1999-01-01

194

Lassa virus entry requires a trigger-induced receptor switch  

PubMed Central

Lassa virus spreads from rodents to humans and can lead to lethal hemorrhagic fever. Despite its broad tropism, chicken cells were reported to resist infection thirty years ago. We show that Lassa virus readily engaged its cell surface receptor ?-dystroglycan in avian cells, but virus entry in susceptible species involved a pH-dependent switch to an intracellular receptor, the lysosome-resident protein LAMP1. Iterative haploid screens revealed that the sialyltransferase ST3GAL4 was required for the interaction of the virus glycoprotein with LAMP1. A single glycosylated residue in LAMP1, present in susceptible species but absent in birds, was essential for interaction with the Lassa virus envelope protein and subsequent infection. The resistance of Lamp1-deficient mice to Lassa virus highlights the relevance of this receptor switch in vivo. PMID:24970085

Jae, Lucas T.; Raaben, Matthijs; Herbert, Andrew S.; Kuehne, Ana I.; Wirchnianski, Ariel S.; Soh, Timothy; Stubbs, Sarah H.; Janssen, Hans; Damme, Markus; Saftig, Paul; Whelan, Sean P.; Dye, John M.; Brummelkamp, Thijn R.

2014-01-01

195

GABA(A)/central benzodiazepine receptor and peripheral benzodiazepine receptor ligands as inducers of phenobarbital-inducible CYP2B and CYP3A.  

PubMed

A sequence critical for phenobarbital (PB) induction, the PB response unit (PBRU), situated upstream of the rat CYP2B1 and CYP2B2 genes, includes two nuclear receptor binding sites, NR1 and NR2. When NR1 and NR2 are mutated PB responsiveness is abolished. While no nuclear receptor for which PB is an agonist ligand has yet been identified, PB is a ligand of GABA(A) receptors and it can displace [(3)H] 1-(2-chlorophenyl)-N-methyl-N-(1-methylpropyl)-3-isoquinolinecarboxamide (PK 11195) from its binding site on the peripheral benzodiazepine receptor (PBR). We assessed CYP2B levels in primary rat hepatocytes following treatment with 10 ligands of either or both of these receptors. All compounds tested were found to be CYP2B1/CYP2B2 inducers and most were CYP3A inducers. Five had not previously been described as CYP2B1/CYP2B2 inducers: bicuculline, flunitrazepam, 4'-chlorodiazepam (Ro5-4864), N,N-dihexyl-2-(4-fluorophenyl)indole-3-acetamide (FGIN 1-27) and 7-(dimethylcarbamoyloxy)-6-phenylpyrrolo-[2,1-d][1,5]benzothiazepine (DCPPBT). Reporter gene analysis demonstrated that CYP2B induction by these agents and other PBR or GABA(A) receptor ligands is mediated through the PBRU and the NR1/NR2 sites, suggesting a molecular mechanism similar to that for PB induction. The potencies for PBRU-dependent induction by 11 ligands of PBR or the GABA(A) receptor was evaluated. FGIN-127, DCPPBT and PK 11195 exhibited EC(50) values for PBRU-dependent transcription activation about three orders of magnitude higher than the reported affinities of the PBR for these agents, arguing against the involvement of the PBR in PB induction. However the EC(50) values found for the agents tested encourage further investigation on the possible involvement of the GABA(A) receptor in PB induction. PMID:15345328

Roberge, Christian; Beaudet, Marie-Josée; Anderson, Alan

2004-10-01

196

Protein-bound uremic toxins induce tissue remodeling by targeting the EGF receptor.  

PubMed

Indoxyl sulfate and p-cresol sulfate have been suggested to induce kidney tissue remodeling. This study aimed to clarify the molecular mechanisms underlying this tissue remodeling using cultured human proximal renal tubular cells and half-nephrectomized mice treated with indoxyl sulfate or p-cresol sulfate as study models. Molecular docking results suggested that indoxyl sulfate and p-cresol sulfate dock on a putative interdomain pocket of the extracellular EGF receptor. In vitro spectrophotometric analysis revealed that the presence of a synthetic EGF receptor peptide significantly decreased the spectrophotometric absorption of indoxyl sulfate and p-cresol sulfate. In cultured cells, indoxyl sulfate and p-cresol sulfate activated the EGF receptor and downstream signaling by enhancing receptor dimerization, and increased expression of matrix metalloproteinases 2 and 9 in an EGF receptor-dependent manner. Treatment of mice with indoxyl sulfate or p-cresol sulfate significantly activated the renal EGF receptor and increased the tubulointerstitial expression of matrix metalloproteinases 2 and 9. In conclusion, indoxyl sulfate and p-cresol sulfate may induce kidney tissue remodeling through direct binding and activation of the renal EGF receptor. PMID:25012179

Sun, Chiao-Yin; Young, Guang-Huar; Hsieh, Yu-Ting; Chen, Yau-Hung; Wu, Mai-Szu; Wu, Vin-Cent; Lee, Jia-Hung; Lee, Chin-Chan

2015-02-01

197

Spinal ephrinB/EphB signalling contributed to remifentanil-induced hyperalgesia via NMDA receptor  

PubMed Central

Background One of the major unresolved issues in treating pain is the paradoxical hyperalgesia produced by opiates, and accumulating evidence implicate that EphBs receptors and ephrinBs ligands are involved in mediation of spinal nociceptive information and central sensitization, but the manner in which ephrinB/EphB signalling acts on spinal nociceptive information networks to produce hyperalgesia remains enigmatic. The objective of this research was to investigate the role of ephrinB/EphB signalling in remifentanil-induced hyperalgesia (RIH) and its downstream effector. Methods We characterized the remifentanil-induced pain behaviours by evaluating thermal hyperalgesia and mechanical allodynia in a rat hind paw incisional model. Protein expression of EphB1 receptor and ephrinB1 ligand in spinal dorsal horn cord was determined by Western blotting, and Fos was determined by immunohistochemistry assay, respectively. To figure out the manner in which ephrinB/EphB signalling acts with N-methyl-d-aspartic acid (NMDA) receptor, we used MK-801, an antagonist of NMDA receptor, trying to suppressed the hyperalgesia induced by ephrinB1-Fc, an agonist of ephrinB/EphB. Results Continuing infusion of remifentanil produced a thermal hyperalgesia and mechanical allodynia, which was accompanied with increased protein expression of spinal-level EphB1 receptor, ephrinB1 ligand and Fos; what appeared above was suppressed by pretreatment with EphB1-Fc, an antagonist of ephrinB/EphB or MK-801, and increased pain behaviours induced by intrathecal injection of ephrinB1-Fc, an agonist of ephrinB/EphB, were suppressed by MK-801. Conclusions Our findings indicated that ephrinB/EphB signalling is involved in RIH. EphrinB/EphB signalling might be the upstream of NMDA receptor. What's already known about this topic? EphBs receptors and ephrinBs ligands are involved in mediation of spinal nociceptive information and central sensitization. The combination of EphB receptor and N-methyl-d-aspartic acid receptor induces long-term potentiation that is critical for causing excitation of spinal neuron and pain hyperalgesia. What does this study add? EphrinB/EphB signalling is involved in remifentanil-induced hyperalgesia (RIH). EphrinB/EphB signalling might be the upstream of N-methyl-d-aspartic acid receptor in RIH. PMID:24737575

Xia, WS; Peng, YN; Tang, LH; Jiang, LS; Yu, LN; Zhou, XL; Zhang, FJ; Yan, M

2014-01-01

198

The Role of Purinergic Receptors in Cancer-Induced Bone Pain  

PubMed Central

Cancer-induced bone pain severely compromises the quality of life of many patients suffering from bone metastasis, as current therapies leave some patients with inadequate pain relief. The recent development of specific animal models has increased the understanding of the molecular and cellular mechanisms underlying cancer-induced bone pain including the involvement of ATP and the purinergic receptors in the progression of the pain state. In nociception, ATP acts as an extracellular messenger to transmit sensory information both at the peripheral site of tissue damage and in the spinal cord. Several of the purinergic receptors have been shown to be important for the development and maintenance of neuropathic and inflammatory pain, and studies have demonstrated the importance of both peripheral and central mechanisms. We here provide an overview of the current literature on the role of purinergic receptors in cancer-induced bone pain with emphasis on some of the difficulties related to studying this complex pain state. PMID:23091774

Falk, Sarah; Uldall, Maria; Heegaard, Anne-Marie

2012-01-01

199

Effect of Ganoderma applanatum mycelium extract on the inhibition of adipogenesis in 3T3-L1 adipocytes.  

PubMed

Ganoderma applanatum (GA) and related fungal species have been used for over 2000 years in China to prevent and treat various human diseases. However, there is no critical research evaluating the functionality of GA grown using submerged culture technology. This study aimed to evaluate the effects of submerged culture GA mycelium (GAM) and its active components (protocatechualdehyde [PCA]) on preadipocyte differentiation of 3T3-L1 cells. Mouse-derived preadipocyte 3T3-L1 cells were treated with differentiation inducers in the presence or absence of GAM extracts. We determined triglyceride accumulations, glycerol-3-phosphate dehydrogenase (GPDH) activities, and differentiation makers. PCA, the active component of GAM extract, was also used to treat 3T3-L1 cells. The MTT assay showed that the GAM extract (0.01-1?mg/mL) was not toxic to 3T3-L1 preadipocyte. Treatment of cells with GAM extracts and its active components significantly decreased the GPDH activity and lipid accumulation, a marker of adipogenesis, in a dose-dependent manner. Western blot analysis results showed that the protein expression levels of peroxisome proliferator-activated receptor ? (PPAR?), CCAAT/enhancer-binding protein ? (C/EBP?), and sterol regulatory element-binding protein 1 (SREBP1) were inhibited by the GAM extract. In addition, adipogenic-specific genes such as perilipin, fatty acid synthase (FAS), fatty acid transport protein 1 (FATP1), and fatty acid-binding protein 4 (FABP4) decreased in a dose-dependent manner. Quantitative high-performance liquid chromatography analysis showed that the GAM extract contained 1.14?mg/g PCA. GAM extracts suppressed differentiation of 3T3-L1 preadipocytes, in part, through altered regulation of PPAR?, C/EBP?, and SREBP1. These results suggest that GAM extracts and PCA may suppress adipogenesis by inhibiting differentiation of preadipocytes. PMID:25140758

Kim, Ji-Eun; Park, Sung-Jin; Yu, Mi-Hee; Lee, Sam-Pin

2014-10-01

200

Glucose-dependent insulinotropic peptide impairs insulin signaling via inducing adipocyte inflammation in glucose-dependent insulinotropic peptide receptor-overexpressing adipocytes.  

PubMed

Glucose-dependent insulinotropic peptide (GIP) exerts multiple biological effects via the G-protein-coupled receptor GIPR, including glucose-stimulated insulin production and secretion, cell proliferation, and antiapoptosis in pancreatic ?-cells. In an obese state, the circulating level of GIP is elevated. GIPR-knockout mice are resistant to high-fat-diet-induced obesity. The rising evidence suggests a potential role of GIP in adipocyte biology and lipid metabolism. In our study, we overexpressed GIPR in 3T3-L1 CAR adipocytes and demonstrated that GIP impaired the physiological functions of adipocytes as a consequence of increased production of inflammatory cytokines and chemokines and phosphorylation of IkB kinase (IKK)-? through activation of the cAMP-PKA pathway. Activation of Jun N-terminal kinase (JNK) pathway was also observed during GIP-induced inflammatory responses in adipocytes. The inhibition of JNK blocked GIP-stimulated secretion of inflammatory cytokines and chemokines, as well as phosphorylation of IKK?. In addition, GIP-induced inflammatory response increased basal glucose uptake but inhibited insulin-stimulated glucose uptake. Moreover, GIP-induced adipocyte inflammation impaired insulin signaling in adipocytes as demonstrated by a reduction of AKT phosphorylation. Our results suggest that GIP might be one of the stimuli attributable to obesity-induced insulin resistance via the induction of adipocyte inflammation. PMID:22366643

Nie, Yaohui; Ma, Ronald C; Chan, Juliana C N; Xu, Haiyan; Xu, Gang

2012-06-01

201

Therapeutics Based On The Induced Internalization Of Surface Receptors  

Cancer.gov

The National Cancer Institute, Laboratory of Cellular Oncology is seeking statements of capability or interest from parties interested in collaborative research to further develop, evaluate, or commercialize therapeutics for diseases or conditions associated with target receptors, such as cancer, angiogenesis, or HIV infections.

202

Prostaglandin E2 Receptor, EP3, Is Induced in Diabetic Islets and Negatively Regulates Glucose-and Hormone-  

E-print Network

Prostaglandin E2 Receptor, EP3, Is Induced in Diabetic Islets and Negatively Regulates Glucose, the gene for the pros- taglandin E receptor 3 (EP3), was upregulated with diabetes. The EP3 receptor involved in the synthesis of PGE2. We hypothesized that increased signaling through EP3 might be coincident

Attie, Alan D.

203

Cocaine-Induced Intracellular Signaling and Gene Expression Are Oppositely Regulated by the Dopamine D1 and D3 Receptors  

Microsoft Academic Search

Repeated exposure to cocaine can induce neuroadaptations in the brain. One mechanism by which persistent changes occur involves alterations in gene expression mediated by the dopamine receptors. Both the dopamine D1 and D3 receptors have been shown to mediate gene expression changes. Moreover, the D1 and D3 receptors are also coexpressed in the same neurons, particularly in the nucleus accumbens

Lu Zhang; Danwen Lou; Hongyuan Jiao; Dongsheng Zhang; Xinkang Wang; Ying Xia; Jianhua Zhang; Ming Xu

2004-01-01

204

Ligand-Induced Alterations in the Phosphorylation State of Ethylene Receptors in Tomato Fruit1[W][OA  

E-print Network

Ligand-Induced Alterations in the Phosphorylation State of Ethylene Receptors in Tomato Fruit1[W fully determined. Here we demonstrate that LeETR4, a critical receptor for tomato (Solanum lycopersicum in tomato fruits. We provide insights into the nature of receptor on and off states. The gaseous plant

Klee, Harry J.

205

The insulin-like growth factor I receptor-induced interaction of insulin receptor substrate-4 and Crk-II.  

PubMed

Stimulation of the insulin or insulin-like growth factor (IGF)-I receptor results in activation of several signaling pathways. Proteins of the insulin receptor substrate (IRS) family play important roles in mediating these signaling cascades. To date, four members of the IRS family of docking proteins have been characterized. Recently, we have reported that stimulation of the IGF-I receptor in 293 HEK cells regulates interaction of the newly discovered IRS-4 molecule with the Crk family of proteins. In the present study, we characterize the molecular basis of these interactions. C- and N termini truncation analysis of IRS-4 demonstrated that the region between amino acids 678 and 800 of the IRS-4 molecule is involved in this interaction. This region contains a cluster of four tyrosines (Y(700), Y(717), Y(743), and Y(779)). We hypothesize that one or more of these tyrosines are involved in the interaction between the SH2 domain of the Crk-II molecule when IRS-4 is phosphorylated upon IGF-I receptor activation. Additional mutational analyses confirmed this hypothesis. Interestingly, none of these four tyrosines was individually critical for the interaction between Crk-II and IRS-4, but when all four tyrosines were simultaneously mutated to phenylalanine, the IGF-I induced interaction between these molecules was abolished. Taken together, these results suggest a novel mechanism of Crk-II binding to tyrosine phosphorylated proteins. PMID:11316748

Karas, M; Koval, A P; Zick, Y; LeRoith, D

2001-05-01

206

Umbelliferone increases the expression of adipocyte-specific genes in 3?t3-l1 adipocyte.  

PubMed

Umbelliferone (UMB), a natural product of coumarin family, has been shown to reduce blood glucose and to improve lipid profiles in streptozotocin (STZ)-induced diabetic rats. Our objective was to examine the effect of UMB on adipogenesis by investigating its stimulatory effect on lipid accumulation and mRNA expression of adipogenic transcription factors and adipocyte-specific genes in 3?T3-L1 preadipocyte culture. An Oil Red O staining was used to monitor lipid accumulation, and we found that UMB treatment at concentration range of 10-100??M significantly increased lipid accumulation of differentiating 3?T3-L1 cells. At the molecular level of adipogenesis, we examined the mRNA expression of adipogenic transcription factors, peroxisome proliferator-activated receptor ?, CCAAT/enhancer-binding protein ?, and sterol regulatory element-binding protein 1c. Those transcription factors were increased by UMB at 10-100??M. Interestingly, UMB also stimulated the mRNA expression of adipocyte-specific genes, adipocyte fatty acid-binding protein, lipoprotein lipase, fatty acid synthase, fatty acid translocase, and adiponectin. Our findings indicate that the stimulatory effect of UMB on adipocyte differentiation likely occurs through up-regulation of adipogenic transcription factors and downstream adipocyte-specific gene expression. PMID:24853372

Naowaboot, Jarinyaporn; Chung, Choon Hee; Choi, Ran; Pannangpetch, Patchareewan

2014-11-01

207

A semisynthetic Eph receptor tyrosine kinase provides insight into ligand-induced kinase activation  

PubMed Central

SUMMARY We have developed a methodology for generating milligram amounts of functional Eph tyrosine kinase receptor using the protein engineering approach of expressed protein ligation. Stimulation with ligand induces efficient autophosphorylation of the semisynthetic Eph construct. The in vitro phosphorylation of key Eph tyrosine residues upon ligand-induced activation was monitored via time-resolved, quantitative phosphoproteomics, suggesting a precise and unique order of phosphorylation of the Eph tyrosines in the kinase activation process. To our knowledge, this work represents the first reported semisynthesis of a receptor tyrosine kinase and provides a potentially general method for producing single-pass membrane proteins for structural and biochemical characterization. PMID:21439481

Singla, Nikhil; Erdjument-Bromage, Hediye; Himanen, Juha P.; Muir, Tom W.; Nikolov, Dimitar B.

2011-01-01

208

Restoration of amphetamine-induced locomotor sensitization in dopamine D 1 receptor-deficient mice  

Microsoft Academic Search

Rationale and objectives  Amphetamine-induced sensitization is thought to involve dopamine D1 receptors. Using mice lacking dopamine D1 receptors (D1?\\/?), we found that they exhibited blunted sensitization to low doses of amphetamine, while others using different treatment\\u000a and testing regimens reported inconsistent results. We investigated whether experimental variables, alteration in gene expression\\u000a or cholinergic input played a role in amphetamine-induced responses.\\u000a \\u000a \\u000a \\u000a Methods  D1?\\/?

Mufida B. El-Ghundi; Theresa Fan; Joanna M. Karasinska; John Yeung; Millee Zhou; Brian F. O’Dowd; Susan R. George

2010-01-01

209

Endothelin Receptor Type B Counteracts Tenascin-C-Induced Endothelin Receptor Type A-Dependent Focal Adhesion and Actin Stress Fiber Disorganization  

Microsoft Academic Search

Tenascin-C, an extracellular matrix molecule of the tumor- specific microenvironment, counteracts the tumor cell prolif- eration-suppressing effect of fibronectin by blocking the integrin A5B1\\/syndecan-4 complex.This causes cell rounding and stimulates tumor cell proliferation.Tenascin-C also stimulates endothelin receptor type A (EDNRA) expression. Here, we investigated whether signaling through endothelin receptors affects tenascin-C-induced cell rounding.We observed that endothelin receptor type B (EDNRB)

Katrin Lange; Martial Kammerer; Monika E. Hegi; Stefan Grotegut; Antje Dittmann; Wentao Huang; Erika Fluri; George W. Yip; Martin Gotte; Christian Ruiz; Gertraud Orend

2007-01-01

210

Postsynaptic 5-HT1B receptors modulate electroshock-induced generalised seizures in rats.  

PubMed

1. Although an important regulatory role for serotonin (5-HT) in seizure activation and propagation is well established, relatively little is known of the function of specific 5-HT receptor subtypes on seizure modulation. 2. The aim of the present study was to investigate the role of 5-HT(1A, 1B and 1D) receptors in modulating generalised seizures in the rat maximal electroshock seizure threshold (MEST) test. 3. The mixed 5-HT receptor agonists SKF 99101 (5-20 mg kg(-1) i.p.) and RU 24969 (1-5 mg kg(-1) i.p.), 0.5 h pretest, both produced marked dose-related increases in seizure threshold. These agents share high affinity for 5-HT(1A, 1B and 1D) receptors. 4. Antiseizure effects induced by submaximal doses of these agonists were maintained following p-chlorophenylalanine (150 mg kg(-1) i.p. x 3 days)-induced 5-HT depletion. 5. The anticonvulsant action of both SKF 99101 (15 mg kg(-1) i.p.) and RU 24969 (2.5 mg kg(-1) i.p.) was dose-dependently abolished by the selective 5-HT1B receptor antagonist SB-224289 (0.1-3 mg kg(-1) p.o., 3 h pretest) but was unaffected by the selective 5-HT1A receptor antagonist WAY 100635 (0.01-0.3 mg kg(-1) s.c., 1 h pretest). This indicates that 5-HT1B receptors are primarily involved in mediating the anticonvulsant properties of these agents. 6. In addition, the ability of the 5-HT(1B/1D) receptor antagonist GR 127935 (0.3-3 mg kg(-1) s.c., 60 min pretest) to dose-dependently inhibit SKF 99101-induced elevation of seizure threshold also suggests possible downstream involvement of 5-HT1D receptors in the action of this agonist, although confirmation awaits the identification of a selective 5-HT1D receptor antagonist. 7. Overall, these data demonstrate that stimulation of postsynaptic 5-HT1B receptors inhibits electroshock-induced seizure spread in rats. PMID:15678098

Stean, Tania O; Atkins, Alan R; Heidbreder, Christian A; Quinn, Leann P; Trail, Brenda K; Upton, Neil

2005-03-01

211

Bile Acid-Induced Arrhythmia Is Mediated by Muscarinic M2 Receptors in Neonatal Rat Cardiomyocytes  

PubMed Central

Background Intrahepatic cholestasis of pregnancy (ICP) is a common disease affecting up to 5% of pregnancies and which can cause fetal arrhythmia and sudden intrauterine death. We previously demonstrated that bile acid taurocholate (TC), which is raised in the bloodstream of ICP, can acutely alter the rate and rhythm of contraction and induce abnormal calcium destabilization in cultured neonatal rat cardiomyocytes (NRCM). Apart from their hepatic functions bile acids are ubiquitous signalling molecules with diverse systemic effects mediated by either the nuclear receptor FXR or by a recently discovered G-protein coupled receptor TGR5. We aim to investigate the mechanism of bile-acid induced arrhythmogenic effects in an in-vitro model of the fetal heart. Methods and Results Levels of bile acid transporters and nuclear receptor FXR were studied by quantitative real time PCR, western blot and immunostaining, which showed low levels of expression. We did not observe functional involvement of the canonical receptors FXR and TGR5. Instead, we found that TC binds to the muscarinic M2 receptor in NRCM and serves as a partial agonist of this receptor in terms of inhibitory effect on intracellular cAMP and negative chronotropic response. Pharmacological inhibition and siRNA-knockdown of the M2 receptor completely abolished the negative effect of TC on contraction, calcium transient amplitude and synchronisation in NRCM clusters. Conclusion We conclude that in NRCM the TC-induced arrhythmia is mediated by the partial agonism at the M2 receptor. This mechanism might serve as a promising new therapeutic target for fetal arrhythmia. PMID:20300620

Sheikh Abdul Kadir, Siti H.; Miragoli, Michele; Abu-Hayyeh, Shadi; Moshkov, Alexey V.; Xie, Qilian; Keitel, Verena; Nikolaev, Viacheslav O.; Williamson, Catherine; Gorelik, Julia

2010-01-01

212

From Chemotherapy-Induced Emesis to Neuroprotection: Therapeutic Opportunities for 5-HT3 Receptor Antagonists.  

PubMed

5-HT3 receptor antagonists are extensively used as efficacious agents in counteracting chemotherapy-induced emesis. Recent investigations have shed light on other potential effects (analgesic, anxiolytic, and anti-psychotic). Some studies have reported neuroprotective properties for the 5-HT3 receptor antagonists in vitro and in vivo. When administered to A?-challenged rat cortical neurons, 5-HT3 receptor antagonists substantially abated apoptosis, elevation of cytosolic Ca(2), glutamate release, reactive oxygen species (ROS) generation, and caspase-3 activity. In addition, in vivo studies show that 5-HT3 receptor antagonists possess, alongside their anti-emetic effects, notable immunomodulatory properties in CNS. We found that pretreatment with tropisetron significantly improved neurological deficits and diminished leukocyte transmigration into the brain, TNF-? level, and brain infarction in a murine model of embolic stroke. Our recent investigation revealed that tropisetron protects against A?-induced neurotoxicity in vivo through both 5-HT3 receptor-dependent and -independent pathways. Tropisetron, in vitro, was found to be an efficacious inhibitor of the signaling pathway leading to the activation of pro-inflammatory NF-?B, a transcription factor pivotal to the upregulation of several neuroinflammatory mediators in brain. This mini review summarizes novel evidence concerning effects of 5-HT3 antagonists and their possible mechanisms of action in ameliorating neurodegenerative diseases including Alzheimer, multiple sclerosis, and stroke. Further, we discuss some newly synthesized 5-HT3 receptor antagonists with dual properties of 5-HT3 receptor blockade/alpha-7 nicotinic receptor activator and their potential in management of memory impairment. Since 5-HT3 receptor antagonists possess a large therapeutic window, they can constitute a scaffold for design and synthesis of new neuroprotective medications. PMID:25377794

Fakhfouri, Gohar; Mousavizadeh, Kazem; Mehr, Sharam Ejtemaei; Dehpour, Ahmad Reza; Zirak, Mohammad Reza; Ghia, Jean-Eric; Rahimian, Reza

2014-11-01

213

Triggering receptor expressed on myeloid cells-1 (TREM-1) amplifies the signals induced by the NACHT-LRR (NLR) pattern recognition receptors  

Microsoft Academic Search

Triggering receptor expressed on myeloid cells-1 (TREM-1) is a member of a new family of myeloid receptors, encoded by a gene cluster linked to the MHC. Engagement of TREM-1 stimulates intracellular signals, resulting in activation of phagocytosis, neutrophil degranulation, and amplification of cytokine production induced by TLRs. In the present study, a novel property following engagement of TREM-1 is described,

Mihai G. Netea; Tania Azam; Gerben Ferwerda; Stephen E. Girardin; Soo-Hyun Kim; Charles A. Dinarello

2006-01-01

214

Methamphetamine Induces Striatal Neurokinin-1 Receptor Endocytosis Primarily in Somatostatin/NPY/NOS Interneurons and the Role of Dopamine Receptors in Mice  

PubMed Central

Methamphetamine (METH) is a psychostimulant that induces long-term deficits of dopamine terminal markers and apoptotic cell death in the striatum. Our laboratory demonstrated that pharmacological blockade of the neurokinin-1 receptor attenuated the METH-induced damage to the striatal dopamine terminals and the apoptotic cell death of some striatal neurons. Here we employed histological methods to assess the effect of METH on neurokinin-1 receptor trafficking in the striatum as an indirect index of signaling by the neuropeptide substance P (natural ligand for this receptor). Male mice received a single injection of METH (30 mg/kg, i.p.) and were sacrificed 30 minutes later. Immunohistofluorescence confocal microscopy confirmed that the neurokinin-1 receptor is located on cholinergic and somatostatin interneurons of the striatum. METH induced the trafficking of the neurokinin-1 receptor from the membrane into cytoplasmic endosomes primarily in the somatostatin/NPY/NOS interneurons and this phenomenon was attenuated by antagonists of the dopamine D1 (SCH-23390), D2 (raclopride) or neurokinin-1 (WIN-51,708) receptors. These data demonstrate that METH induces the trafficking of the striatal neurokinin-1 receptors principally in the somatostatin/NPY/NOS interneurons and that this phenomenon is dependent on the activity of dopamine D1 and D2 receptors. PMID:20730802

Wang, Jing; Angulo, Jesus A.

2010-01-01

215

Significance of the progesterone receptor and epidermal growth factor receptor, but not the estrogen receptor, in chemically induced lung carcinogenesis in female A/J mice  

PubMed Central

In the present study, the expression levels of female hormone receptors, estrogen receptor (ER) and progesterone receptor (PR) and the epidermal growth factor receptor, (EGFR), as well as proliferating cell nuclear antigen (PCNA) were examined in lung tumors that were induced by 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in female A/J mice. Each seven-week-old mouse was administered with 2 mg NNK via intraperitoneal injection and the mice were subsequently euthanized at week 52. Lung tumors, including adenomas, carcinomas in adenomas and adenocarcinomas, were obtained and analyzed by immunohistochemistry for the expression levels of the receptors, ER, PR and EGFR, and PCNA. The results were as follows: i) In mouse lung adenomas, a significant correlation was identified between the size of the tumor and PCNA expression, although not with the expression of the receptors (ER, PR and EGFR); ii) in the carcinoma components of the carcinomas in adenomas, the size of the tumor and PCNA expression were correlated, while EGFR expression demonstrated a significant correlation with PR expression; iii) in adenocarcinomas, the tumor size significantly correlated with PCNA, EGFR and PR expression; and iv) EGFR and PR expression was identified to be significantly correlated in adenocarcinomas, and to a certain extent in the carcinoma components of the carcinomas in adenomas, although not in the adenomas. Notably, ER expression was not associated with tumor growth or the other factors, particularly EGFR expression, and no significant differences were identified between the three types of lesion. These results indicate that PR, like EGFR, may be significant in lung carcinogenesis. PMID:25364399

KISHI, SOSUKE; YOKOHIRA, MASANAO; YAMAKAWA, KEIKO; SAOO, KOUSUKE; IMAIDA, KATSUMI

2014-01-01

216

Antinociceptive effects induced through the stimulation of spinal cannabinoid type 2 receptors in chronically inflamed mice.  

PubMed

The stimulation of spinal cannabinoid type 2 (CB(2)) receptors is a suitable strategy for the alleviation of experimental pain symptoms. Several reports have described the up-regulation of spinal cannabinoid CB(2) receptors in neuropathic settings together with the analgesic effects derived from their activation. Besides, we have recently reported in two murine bone cancer models that the intrathecal administration of cannabinoid CB(2) receptor agonists completely abolishes hyperalgesia and allodynia, whereas spinal cannabinoid CB(2) receptor expression remains unaltered. The present experiments were designed to measure the expression of spinal cannabinoid CB(2) receptors as well as the analgesic efficacy derived from their stimulation in mice chronically inflamed by the intraplantar injection of complete Freund's adjuvant 1 week before. Both spinal cannabinoid CB(2) receptors mRNA measured by real-time PCR and cannabinoid CB(2) receptor protein levels measured by western blot remained unaltered in inflamed mice. Besides, the intrathecal (i.t.) administration of the cannabinoid CB(2) receptor agonists AM1241, (R,S)-3-(2-Iodo-5-nitrobenzoyl)-1-(1-methyl-2-piperidinylmethyl)-1H-indole, (0.03-1 ?g) and JWH 133, (6aR,10aR)-3-(1,1-Dimethylbutyl)-6a,7,10,10a-tetrahydro-6,6,9-trimethyl-6H-dibenzo[b,d]pyran, (3-30 ?g) dose-dependently blocked inflammatory thermal hyperalgesia and mechanical allodynia. The analgesic effects induced by both agonists were counteracted by the coadministration of the selective cannabinoid CB(2) receptor antagonist SR144528, 5-(4-chloro-3-methylphenyl)-1-[(4-methylphenyl)methyl]-N-[(1S,2S,4R)-1,3,3-trimethylbicyclo[2.2.1]hept-2-yl]-1H-pyrazole-3-carboxamide, (5 ?g) but not by the cannabinoid CB(1) receptor antagonist AM251, N-(Piperidin-1-yl)-5-(4-iodophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide, (10 ?g). The effects induced by AM1241 were also inhibited by the coadministration of the opioid receptor antagonist, naloxone (1 ?g). These results demonstrate that effective analgesia can be achieved in chronic inflammatory settings through the stimulation of spinal cannabinoid CB(2) receptors even if this receptor population is not up-regulated. PMID:21771590

Curto-Reyes, Verdad; Boto, Tamara; Hidalgo, Agustín; Menéndez, Luis; Baamonde, Ana

2011-10-01

217

Retinoids induce integrin-independent lymphocyte adhesion through RAR-? nuclear receptor activity.  

PubMed

Oxidative metabolites of vitamin A, in particular all-trans-retinoic acid (atRA), have emerged as key factors in immunity by specifying the localization of immune cells to the gut. Although it is appreciated that isomers of retinoic acid activate the retinoic acid receptor (RAR) and retinoid X receptor (RXR) family of nuclear receptors to elicit cellular changes, the molecular details of retinoic acid action remain poorly defined in immune processes. Here we employ a battery of agonists and antagonists to delineate the specific nuclear receptors utilized by retinoids to evoke lymphocyte cell adhesion to ADAM (adisintegrin and metalloprotease) protein family members. We report that RAR agonism is sufficient to promote immune cell adhesion in both immortal and primary immune cells. Interestingly, adhesion occurs independent of integrin function, and mutant studies demonstrate that atRA-induced adhesion to ADAM members required a distinct binding interface(s) as compared to integrin recognition. Anti-inflammatory corticosteroids as well as 1,25-(OH)2D3, a vitamin D metabolite that prompts immune cell trafficking to the skin, potently inhibited the observed adhesion. Finally, our data establish that induced adhesion was specifically attributable to the RAR-? receptor isotype. The current study provides novel molecular resolution as to which nuclear receptors transduce retinoid exposure into immune cell adhesion. PMID:25450689

Whelan, Jarrett T; Wang, Lei; Chen, Jianming; Metts, Meagan E; Nasser, Taj A; McGoldrick, Liam J; Bridges, Lance C

2014-10-31

218

Phorbol ester induced phosphorylation of the estrogen receptor in intact MCF-7 human breast cancer cells  

SciTech Connect

Recent studies with a variety of cellular receptors have shown that phorbol ester induced phosphorylation modulates ligand binding and function. In this study the authors present direct evidence that the estrogen receptor in MCF-7 human breast cancer cells is a phosphoprotein whose phosphorylation state can be enhanced specifically by phorbol-12-myristate-13-acetate (PMA). Cells were cultured to 6h in the presence of (/sup 32/P)-orthophosphate. Whole cell extracts were immunoprecipitated with a monoclonal antibody (D58) against the estrogen receptor and subjected to SDS-polyacrylamide electrophoresis. Autoradiography showed a specific band in the region of 60-62 kDa which was significantly increased in preparations from PMA treated cells. Phospho-amino acid analysis demonstrated specific phosphorylation of serine and threonine residues. Cholera toxin or forskolin did not change the phosphorylation state of this protein. In a parallel binding analysis PMA led to a rapid decrease of estrogen binding sites. The estrogen induction of both progesterone receptors and growth in semisolid medium was blocked by PMA, whereas the estrogen induction of the 8kDa protein corresponding to the ps2 gene product and of the 52 kDa protein was not affected. In conclusion, phorbol esters can induce phosphorylation of the estrogen receptor. This process may be associated with the inactivation of certain receptor functions.

Knabbe, C.; Lippman, M.E.; Greene, G.L.; Dickson, R.B.

1986-05-01

219

Drug-induced mild therapeutic hypothermia obtained by administration of a transient receptor potential vanilloid type 1 agonist  

PubMed Central

Background The use of mechanical/physical devices for applying mild therapeutic hypothermia is the only proven neuroprotective treatment for survivors of out of hospital cardiac arrest. However, this type of therapy is cumbersome and associated with several side-effects. We investigated the feasibility of using a transient receptor potential vanilloid type 1 (TRPV1) agonist for obtaining drug-induced sustainable mild hypothermia. Methods First, we screened a heterogeneous group of TRPV1 agonists and secondly we tested the hypothermic properties of a selected candidate by dose-response studies. Finally we tested the hypothermic properties in a large animal. The screening was in conscious rats, the dose-response experiments in conscious rats and in cynomologus monkeys, and the finally we tested the hypothermic properties in conscious young cattle (calves with a body weight as an adult human). The investigated TRPV1 agonists were administered by continuous intravenous infusion. Results Screening: Dihydrocapsaicin (DHC), a component of chili pepper, displayed a desirable hypothermic profile with regards to the duration, depth and control in conscious rats. Dose-response experiments: In both rats and cynomologus monkeys DHC caused a dose-dependent and immediate decrease in body temperature. Thus in rats, infusion of DHC at doses of 0.125, 0.25, 0.50, and 0.75 mg/kg/h caused a maximal ?T (°C) as compared to vehicle control of -0.9, -1.5, -2.0, and -4.2 within approximately 1 hour until the 6 hour infusion was stopped. Finally, in calves the intravenous infusion of DHC was able to maintain mild hypothermia with ?T > -3°C for more than 12 hours. Conclusions Our data support the hypothesis that infusion of dihydrocapsaicin is a candidate for testing as a primary or adjunct method of inducing and maintaining therapeutic hypothermia. PMID:20932337

2010-01-01

220

Insulin Receptor Substrate 1 Overexpression in Human Hepatocellular Carcinoma Cells Prevents Transforming Growth Factor fl-induced Apoptosis  

Microsoft Academic Search

Insulin-like growth factors initiate tyrosyl phosphorylation of the insu lin receptor substrate 1 (IRS-i) protein and activate multiple signaling pathways essential for liver growth. This gene has been found to be up-regulated in human hepatocellular carcinomas (HCCs), and overex pression ofIRS-1 in NIH 3T3 cells leads to malignant transformation with activation of the mitogen-activated protein kinase cascade. To explore another

Shinji Tanaka; Jack R. Wands

221

NOP Receptor Mediates Anti-analgesia Induced by Agonist-Antagonist Opioids  

PubMed Central

Clinical studies have shown that agonist-antagonist opioid analgesics that produce their analgesic effect via action on the kappa-opioid receptor, produce a delayed-onset anti-analgesia in men but not women, an effect blocked by co-administration of a low dose of naloxone. We now report the same time-dependent anti-analgesia and its underlying mechanism in an animal model. Using the Randall-Selitto paw-withdrawal assay in male rats, we found that nalbuphine, pentazocine, and butorphanol each produced analgesia during the first hour followed by anti-analgesia starting at ~90 minutes after administration in males but not females, closely mimicking its clinical effects. As observed in humans, co-administration of nalbuphine with naloxone in a dose ratio of 12.5:1 blocked anti-analgesia but not analgesia. Administration of the highly selective kappa-opioid receptor agonist U69,593 produced analgesia without subsequent anti-analgesia, and confirmed by the failure of the selective kappa antagonist nor-binaltorphimine to block nalbuphine-induced anti-analgesia, indicating that anti-analgesia is not mediated by kappa-opioid receptors. We therefore tested the role of other receptors in nalbuphine anti-analgesia. Nociceptin/orphanin FQ (NOP) and sigma-1 and sigma-2 receptors were chosen on the basis of their known anti-analgesic effects and receptor binding studies. The selective NOP receptor antagonists, JTC801, and J113397, but not the sigma receptor antagonist, BD 1047, antagonized nalbuphine anti-analgesia. Furthermore, the NOP receptor agonist NNC 63-0532 produced anti-analgesia with the same delay in onset observed with the three agonist-antagonists, but without producing preceding analgesia and this anti-analgesia was also blocked by naloxone. These results strongly support the suggestion that clinically used agonist-antagonists act at the NOP receptor to produce anti-analgesia. PMID:24188792

Gear, Robert W.; Bogen, Oliver; Ferrari, Luiz F.; Green, Paul G.; Levine, Jon D.

2014-01-01

222

NOP receptor mediates anti-analgesia induced by agonist-antagonist opioids.  

PubMed

Clinical studies have shown that agonist-antagonist opioid analgesics that produce their analgesic effect via action on the kappa-opioid receptor, produce a delayed-onset anti-analgesia in men but not women, an effect blocked by co-administration of a low dose of naloxone. We now report the same time-dependent anti-analgesia and its underlying mechanism in an animal model. Using the Randall-Selitto paw-withdrawal assay in male rats, we found that nalbuphine, pentazocine, and butorphanol each produced analgesia during the first hour followed by anti-analgesia starting at ?90min after administration in males but not females, closely mimicking its clinical effects. As observed in humans, co-administration of nalbuphine with naloxone in a dose ratio of 12.5:1 blocked anti-analgesia but not analgesia. Administration of the highly selective kappa-opioid receptor agonist U69593 produced analgesia without subsequent anti-analgesia, and confirmed by the failure of the selective kappa antagonist nor-binaltorphimine to block nalbuphine-induced anti-analgesia, indicating that anti-analgesia is not mediated by kappa-opioid receptors. We therefore tested the role of other receptors in nalbuphine anti-analgesia. Nociceptin/orphanin FQ (NOP) and sigma-1 and sigma-2 receptors were chosen on the basis of their known anti-analgesic effects and receptor binding studies. The selective NOP receptor antagonists, JTC801, and J-113397, but not the sigma receptor antagonist, BD 1047, antagonized nalbuphine anti-analgesia. Furthermore, the NOP receptor agonist NNC 63-0532 produced anti-analgesia with the same delay in onset observed with the three agonist-antagonists, but without producing preceding analgesia and this anti-analgesia was also blocked by naloxone. These results strongly support the suggestion that clinically used agonist-antagonists act at the NOP receptor to produce anti-analgesia. PMID:24188792

Gear, R W; Bogen, O; Ferrari, L F; Green, P G; Levine, J D

2014-01-17

223

Tryptophol induces death receptor (DR) 5-mediated apoptosis in U937 cells.  

PubMed

Tryptophol is a natural component isolated from vinegar produced from the boiled extract of black soybean. We have reported that tryptophol induces apoptosis in U937 cells via activation of caspase-8 followed by caspase-3. Tryptophol, however, did not affect human peripheral blood lymphocytes (PBL). In this study, we found that tryptophol enhances formation of a death-inducing signaling complex including death receptor (DR) 5. Cell viability and induction of apoptosis by tryptophol was reduced by transfection with decoy receptor (DcR) 1. These results indicate that tryptophol induces apoptosis through DR5 and that the resistance of PBL to tryptophol-induced apoptosis might be due to competition from DcR1. PMID:17690453

Inagaki, Shyuichiro; Morimura, Shigeru; Tang, Yueqin; Akutagawa, Hiroshi; Kida, Kenji

2007-08-01

224

Interactions of PPAR-alpha and adenosine receptors in hypoxia-induced angiogenesis.  

PubMed

Hypoxia and adenosine are known to upregulate angiogenesis; however, the role of peroxisome proliferator-activated receptor alpha (PPAR?) in angiogenesis is controversial. Using transgenic Tg(fli-1:EGFP) zebrafish embryos, interactions of PPAR? and adenosine receptors in angiogenesis were evaluated under hypoxic conditions. Epifluorescent microscopy was used to assess angiogenesis by counting the number of intersegmental (ISV) and dorsal longitudinal anastomotic vessel (DLAV) at 28 h post-fertilization (hpf). Hypoxia (6h) stimulated angiogenesis as the number of ISV and DLAV increased by 18-fold (p<0.01) and 100 ± 8% (p<0.001), respectively, at 28 hpf. Under normoxic and hypoxic conditions, WY-14643 (10 ?M), a PPAR? activator, stimulated angiogenesis at 28 hpf, while MK-886 (0.5 ?M), an antagonist of PPAR?, attenuated these effects. Compared to normoxic condition, adenosine receptor activation with NECA (10 ?M) promoted angiogenesis more effectively under hypoxic conditions. Involvement of A2B receptor was implied in hypoxia-induced angiogenesis as MRS-1706 (10nM), a selective A2B antagonist attenuated NECA (10 ?M)-induced angiogenesis. NECA- or WY-14643-induced angiogenesis was also inhibited by miconazole (0.1 ?M), an inhibitor of epoxygenase dependent production of eicosatrienoic acid (EET) epoxide. Thus, we conclude that: activation of PPAR? promoted angiogenesis just as activation of A2B receptors through an epoxide dependent mechanism. PMID:24050945

Rizvi, Yasmeen Q; Mehta, Chander S; Oyekan, Adebayo

2013-01-01

225

Pharmacological evaluation of SN79, a sigma (?) receptor ligand, against methamphetamine-induced neurotoxicity in vivo.  

PubMed

Methamphetamine is a highly addictive psychostimulant drug of abuse, causing hyperthermia and neurotoxicity at high doses. Currently, there is no clinically proven pharmacotherapy to treat these effects of methamphetamine, necessitating identification of potential novel therapeutic targets. Earlier studies showed that methamphetamine binds to sigma (?) receptors in the brain at physiologically relevant concentrations, where it "acts in part as an agonist." SN79 (6-acetyl-3-(4-(4-(4-florophenyl)piperazin-1-yl)butyl)benzo[d]oxazol-2(3H)-one) was synthesized as a putative ? receptor antagonist with nanomolar affinity and selectivity for ? receptors over 57 other binding sites. SN79 pretreatment afforded protection against methamphetamine-induced hyperthermia and striatal dopaminergic and serotonergic neurotoxicity in male, Swiss Webster mice (measured as depletions in striatal dopamine and serotonin levels, and reductions in striatal dopamine and serotonin transporter expression levels). In contrast, di-o-tolylguanidine (DTG), a well established ? receptor agonist, increased the lethal effects of methamphetamine, although it did not further exacerbate methamphetamine-induced hyperthermia. Together, the data implicate ? receptors in the direct modulation of some effects of methamphetamine such as lethality, while having a modulatory role which can mitigate other methamphetamine-induced effects such as hyperthermia and neurotoxicity. PMID:22921523

Kaushal, Nidhi; Seminerio, Michael J; Robson, Matthew J; McCurdy, Christopher R; Matsumoto, Rae R

2013-08-01

226

Dopamine receptors and the persistent neurovascular dysregulation induced by methamphetamine self-administration in rats.  

PubMed

Recently abstinent methamphetamine (Meth) abusers showed neurovascular dysregulation within the striatum. The factors that contribute to this dysregulation and the persistence of these effects are unclear. The current study addressed these knowledge gaps. First, we evaluated the brains of rats with a history of Meth self-administration following various periods of forced abstinence. Micro-computed tomography revealed a marked reduction in vessel diameter and vascular volume uniquely within the striatum between 1 and 28 days after Meth self-administration. Microvessels showed a greater impairment than larger vessels. Subsequently, we determined that dopamine (DA) D2 receptors regulated Meth-induced striatal vasoconstriction via acute noncontingent administration of Meth. These receptors likely regulated the response to striatal hypoxia, as hypoxia inducible factor 1? was elevated. Acute Meth exposure also increased striatal levels of endothelin receptor A and decreased neuronal nitric oxide synthase. Collectively, the data provide novel evidence that Meth-induced striatal neurovascular dysregulation involves DA receptor signaling that results in vasoconstriction via endothelin receptor A and nitric oxide signaling. As these effects can lead to hypoxia and trigger neuronal damage, these findings provide a mechanistic explanation for the selective striatal toxicity observed in the brains of Meth-abusing humans. PMID:25185214

Kousik, Sharanya M; Napier, T Celeste; Ross, Ryan D; Sumner, D Rick; Carvey, Paul M

2014-11-01

227

Activation of the D1 receptors inhibits the long-term potentiation in vivo induced by acute morphine administration through a D1-GluN2A interaction in the nucleus accumbens.  

PubMed

Dopamine D1-like receptors can modulate glutamate-mediated excitatory synaptic neurotransmission, but the underlying molecular mechanism remains elusive. Here, we report that acute in-vivo morphine administration induces the long-term potentiation (Mor-LTP) of field excitatory postsynaptic potentials at the prefrontal cortex-to-nucleus accumbens shell synapses, and this process requires the activation of GluN2A-containing N-methyl-D-aspartate receptors. This Mor-LTP is completely inhibited by the D1-like receptor agonist SKF81297, but not by the D2-like receptor agonist quinpirole. SKF81297-inhibited Mor-LTP is restored by pretreatment with the TAT-conjugated interfering peptide TAT-D1-t3, which is a synthetic blocker of the direct D1-GluN2A receptor interaction. These results indicate that the activation of D1 receptors modulates Mor-LTP by the direct D1-GluN2A interaction at the prefrontal cortex-to-nucleus accumbens shell synapses and might play a role in addiction-related plastic alterations. PMID:25121622

Zheng, Qiaohua; Liu, Zhiqiang; Wei, Chunling; Han, Jing; Liu, Yihui; Zhang, Xia; Ren, Wei

2014-10-22

228

Hydrogen sulphide induces ? opioid receptor-dependent analgesia in a rodent model of visceral pain  

PubMed Central

Background Hydrogen sulphide (H2S) is a gaseous neuro-mediator that exerts analgesic effects in rodent models of visceral pain by activating KATP channels. A body of evidence support the notion that KATP channels interact with endogenous opioids. Whether H2S-induced analgesia involves opioid receptors is unknown. Methods The perception of painful sensation induced by colorectal distension (CRD) in conscious rats was measured by assessing the abdominal withdrawal reflex. The contribution of opioid receptors to H2S-induced analgesia was investigated by administering rats with selective ?, ? and ? opioid receptor antagonists and antisenses. To investigate whether H2S causes ? opioid receptor (MOR) transactivation, the neuronal like cells SKNMCs were challenged with H2S in the presence of MOR agonist (DAMGO) or antagonist (CTAP). MOR activation and phosphorylation, its association to ? arrestin and internalization were measured. Results H2S exerted a potent analgesic effects on CRD-induced pain. H2S-induced analgesia required the activation of the opioid system. By pharmacological and molecular analyses, a robust inhibition of H2S-induced analgesia was observed in response to central administration of CTAP and MOR antisense, while ? and ? receptors were less involved. H2S caused MOR transactivation and internalization in SKNMCs by a mechanism that required AKT phosphorylation. MOR transactivation was inhibited by LY294002, a PI3K inhibitor, and glibenclamide, a KATP channels blocker. Conclusions This study provides pharmacological and molecular evidence that antinociception exerted by H2S in a rodent model of visceral pain is modulated by the transactivation of MOR. This observation provides support for development of new pharmacological approaches to visceral pain. PMID:20540729

2010-01-01

229

A molecular mechanism for sensory adaptation based on ligand-induced receptor modification.  

PubMed Central

Physiological responses mediated by cell-surface receptors frequently adapt or "desensitize" (i.e., terminate despite persistent occupancy of receptors by ligand). Binding of ligands to the external domains of a wide variety of surface receptors induces covalent modification of their cytoplasmic domains. A mechanism is presented in which the variety of receptor states generated by ligand binding and covalent modification act together to regulate physiological responsiveness. The development of the model is guided by observations of adaptation for chemotaxis in Escherichia coli and adenylate cyclase activation in Dictyostelium. The general features of the marked response and eventual exact adaptation predicted by the model match those observed in the experimental systems. PMID:3010308

Knox, B E; Devreotes, P N; Goldbeter, A; Segel, L A

1986-01-01

230

Effects of ginseng saponins on responses induced by various receptor stimuli  

Microsoft Academic Search

We investigated the effects of four ginseng saponins, ginsenoside-Rb1, -Rg2, -Rg3 and -Ro, on the responses induced by receptor stimulation of various stimuli. Ginsenoside-Rg2 (1–100 ?M) reduced the secretions of catecholamines from bovine adrenal chromaffin cells stimulated by acetylcholine and ?-aminobutyric acid but not by angiotensin II, bradykinin, histamine and neurotensin. In guinea-pig, the ginsenoside also diminished the nicotine-induced secretion

Eiichi Tachikawa; Kenzo Kudo; Kazuho Harada; Takeshi Kashimoto; Yoshikazu Miyate; Atsushi Kakizaki; Eiji Takahashi

1999-01-01

231

Increased Ischemia-Induced Angiogenesis in the Staggerer Mouse, a Mutant of the Nuclear Receptor Ror  

Microsoft Academic Search

Ror is an orphan nuclear receptor. In homozygous staggerer mutant mice (Rorasg\\/sg), a deletion within the Rora gene leads to an overexpression of inflammatory cytokines. Because inflammation and hypoxia are 2 key stimuli of ischemia-induced angiogenesis, we studied the role of Ror in this setting. Ischemia was induced by ligation of the right femoral artery in C57BL\\/6 Rora\\/ and Rorasg\\/sg

Sandrine Besnard; Jean-Sébastien Silvestre; Micheline Duriez; Joëlle Bakouche; Yolande Lemaigre-Dubreuil; Jean Mariani; Bernard I. Levy; Alain Tedgui

2001-01-01

232

Signal transduction through the fibronectin receptor induces collagenase and stromelysin gene expression  

Microsoft Academic Search

We have investigated the effects of ligation of the fibronectin receptor (FnR) on gene expression in rabbit synovial fibroblasts. Monoclonal antibodies to the FnR that block initial adhesion of fibroblasts to fibronectin induced the expression of genes encoding the secreted extracellular matrix-degrading metallo- proteinases collagenase and stromelysin. That induc- tion was a direct consequence of interaction with the FnR was

Zena Werb; Patrice M. Tremble; Ole Behrendtsen; Eileen Crowley; Caroline H. Damskytll

1989-01-01

233

Endothelin-induced calcium signaling in cultured mouse microglial cells is mediated through ETB receptors.  

PubMed

Microglial cells are the intrinsic immunocompetent cells of the central nervous system, which are activated by brain tissue damage. In this paper we investigated the ability of endothelins (ETs), which are potent vasoconstrictors, to induce intracellular calcium signals in cultured microglia cells. Both endothelin-1 and endothelin-3 increased intracellular Ca2+ concentration ([Ca2+]i). These [Ca2+]i transients were mimicked by BQ3020, an ETB receptor agonist and blocked by BQ788, a selective ETB antagonist, respectively. The calcium signals induced by the endothelins persisted in Ca(2+)-free media. Transcripts encoding the ETB receptor were detected in purified microglial cultures and cDNA fragments derived from ETB receptor mRNA were amplified from 9% of electrophysiologically characterized microglial cells by the use of single-cell RT-PCR. PMID:9243597

Möller, T; Kann, O; Prinz, M; Kirchhoff, F; Verkhratsky, A; Kettenmann, H

1997-07-01

234

Guanine nucleotide regulation of dopamine receptor agonist affinity states in rat estradiol-induced pituitary tumors  

SciTech Connect

The authors have investigated dopamine (DA) receptor agonist high- and low-affinity states in female rate estradiol-induced prolactin (PRL)-secreting pituitary tumors and intact pituitary tissue. Estradiol treatment increased the anterior pituitary weight 9-fold and plasma prolactin levels 74-fold and these measures are correlated (R = 0.745, n = 73, p < 0.001). Competition for (/sup 3/H)-spiperone binding to the DA receptor by apomorphine was compared in normal and adenomatous pituitary tissue. The inhibition constants (Ki) and the proportions of the two apomorphine sites are unchanged in tumors compared to intact pituitary tissue. Guanosine 5'-(..beta..-..gamma..-imino)triphosphate (Gpp(NH)p) causes complete conversion of the high into low affinity dopaminergic agonist site in normal pituitary and in tumors. These results suggest that rats with primary estradiol-induced pituitary tumors have normal and functional DA receptors. 9 references, 2 tables.

Di Paolo, T.; Falardeau, P.

1987-08-31

235

Liver X receptor ? activation induces pyroptosis of human and murine colon cancer cells.  

PubMed

Liver X receptors (LXRs) have been proposed to have some anticancer properties, through molecular mechanisms that remain elusive. Here we report for the first time that LXR ligands induce caspase-1-dependent cell death of colon cancer cells. Caspase-1 activation requires Nod-like-receptor pyrin domain containing 3 (NLRP3) inflammasome and ATP-mediated P2 × 7 receptor activation. Surprisingly, LXR? is mainly located in the cytoplasm and has a non-genomic role by interacting with pannexin 1 leading to ATP secretion. Finally, LXR ligands have an antitumoral effect in a mouse colon cancer model, dependent on the presence of LXR?, pannexin 1, NLRP3 and caspase-1 within the tumor cells. Our results demonstrate that LXR?, through pannexin 1 interaction, can specifically induce caspase-1-dependent colon cancer cell death by pyroptosis. PMID:25124554

Derangère, V; Chevriaux, A; Courtaut, F; Bruchard, M; Berger, H; Chalmin, F; Causse, S Z; Limagne, E; Végran, F; Ladoire, S; Simon, B; Boireau, W; Hichami, A; Apetoh, L; Mignot, G; Ghiringhelli, F; Rébé, C

2014-12-01

236

Cyclic stretch induces human bladder smooth muscle cell proliferation in vitro through muscarinic receptors.  

PubMed

The present study aimed to investigate whether the cyclic stretch?induced proliferation of human bladder smooth muscle cells (HBSMCs) is mediated by muscarinic (M) receptors, together with the signal transduction mechanisms involved in this process. HBSMCs seeded onto silicone membranes were subjected to different cyclic stretches (5, 10, 15 and 20%) for 6 and 12 h. As the effect of cyclic stretch on M2 and M3 mRNA expression levels was maximal at 6 h 10% stretch, all subsequent experiments were performed at this stretch. Western blot analysis was used to quantify M2, M3, protein kinase C (PKC) and phosphorylated (p)?PKC protein expression levels, flow cytometry was employed to examine cell cycle distribution and a 5-bromo?2-deoxyuridine (BrdU) incorporation assay was used to assess cell proliferation at this stretch. Subsequently, HBSMCs were exposed to different acetylcholine concentrations and/or cyclic stretch, M receptor antagonists [AF-DX16, an M2 receptor antagonist; 1,1-dimethyl-4-diphenylacetoxypiperidinium iodide (4-DAMP), an M3 receptor antagonist and atropine, a non?selective antagonist] and GF 109203X, a PKC antagonist, to assess the possible underlying signaling mechanisms. Cyclic stretch was found to increase the proliferation of HBSMCs and the expression levels of M2, M3, PKC and p?PKC proteins. M receptor and PKC antagonists exerted no apparent effect on nonstretched cells, but reduced the incorporation of BrdU into stretched cells; the most pronounced effects were observed when non?selective M receptor and PKC antagonists were applied. Notably, 4?DAMP did not inhibit stretch?induced PKC activation. These results indicate that the activation of the M3 receptor signaling pathway in stretch?induced HBSMC proliferation occurs via PKC-independent mechanisms. PMID:25412212

Dai, Yi; Tian, Ye; Luo, De-Yi; Wazir, Romel; Yue, Xuan; Li, Hong; Wang, Kun-Jie

2015-03-01

237

Neurokinin B induces oedema formation in mouse lung via tachykinin receptor-independent mechanisms.  

PubMed

The tachykinin neurokinin B (NKB) has been implicated in the hypertension that characterises pre-eclampsia, a condition where tissue oedema is also observed. The ability of NKB, administered intradermally or intravenously, to induce oedema formation (assessed as plasma extravasation) was examined by extravascular accumulation of intravenously injected (125)I-albumin in wild-type and tachykinin NK(1) receptor knockout mice. Intradermal NKB (30-300 pmol) caused dose-dependent plasma extravasation in wild-type (P < 0.05) but not NK(1) knockout mice, indicating an essential role for the NK(1) receptor in mediating NKB-induced skin oedema. Intravenous administration of NKB to wild-type mice produced plasma extravasation in skin, uterus, liver (P < 0.05) and particularly in the lung (P < 0.01). Surprisingly, the same doses of NKB led to plasma extravasation in the lung and liver of NK(1) knockout mice. By comparison, the tachykinin substance P induced only minimal plasma extravasation in the lungs of wild-type mice. The plasma extravasation produced by NKB in the lungs of NK(1) receptor knockout mice was unaffected by treatment with the NK(2) receptor antagonist SR48968 (3 mg kg(-1)), by the NK(3) receptor antagonists SR142801 (3 mg kg(-1)) and SB-222200 (5 mg kg(-1)) or by the cyclo-oxygenase (COX) inhibitor indomethacin (20 mg kg(-1)). L-Nitro-arginine methyl ester (15 mg kg(-1)), an inhibitor of endothelial nitric oxide synthase (eNOS), produced only a partial inhibition. We conclude that NKB is a potent stimulator of plasma extravasation through two distinct pathways: via activation of NK(1) receptors, and via a novel neurokinin receptor-independent pathway specific to NKB that operates in the mouse lung. These findings are in keeping with a role for NKB in mediating plasma extravasation in diseases such as pre-eclampsia. PMID:12231654

Grant, Andrew D; Akhtar, Roksana; Gerard, Norma P; Brain, Susan D

2002-09-15

238

Toll Like Receptor-4 Mediates Vascular Inflammation and Insulin Resistance in Diet-Induced Obesity  

Technology Transfer Automated Retrieval System (TEKTRAN)

Vascular dysfunction is a major complication of metabolic disorders such as diabetes and obesity. The current studies were undertaken to determine if inflammatory responses are activated in the vasculature of mice with diet-induced obesity (DIO), and if so, whether Toll Like Receptor-4 (TLR4), a ke...

239

HIGH GLUCOSE INDUCES TOLL-LIKE RECEPTOR EXPRESSION IN HUMAN MONOCYTES: MECHANISM OF ACTIVATION  

Technology Transfer Automated Retrieval System (TEKTRAN)

Objective: Hyperglycemia induced inflammation is central in diabetes complications and monocytes are important in orchestrating these effects. Toll-like receptors (TLRs) play a key role in innate immune responses as well as inflammation. However, there is a paucity of data examining the expression a...

240

Peroxisome Proliferator-Activated Receptor-/ Protects Against Chemically Induced Liver Toxicity in Mice  

E-print Network

carbon tetrachlo- ride (CCl4) hepatoxicity was also observed in PPAR / -null as compared with wild activation of AOM and CCl4 were observed between wild-type or PPAR / - null mice in response to CCl4 against liver toxicity induced by AOM and CCl4, suggesting that this receptor is hepatoprotective against

Omiecinski, Curtis

241

Retinoid-induced chromatin structure alterations in the retinoic acid receptor beta2 promoter.  

PubMed Central

Transcription of the retinoic acid receptor beta2 (RARbeta2) gene is induced by retinoic acid (RA) in mouse P19 embryonal carcinoma (EC) cells. Here we studied RA-induced chromatin structure alterations in the endogenous RARbeta2 promoter and in an integrated, multicopy RARbeta2 promoter in EC cells. RA markedly increased restriction site accessibility within the promoter, including a site near the RA responsive element (RARE) to which the nuclear receptor retinoid X receptor (RXR)-RAR heterodimer binds. These changes coincided with RA-induced alterations in the DNase I hypersensitivity pattern in and around the promoter. These changes became undetectable upon removal of RA, which coincided with the extinction of transcription. Analyses with receptor-selective ligands and an antagonist showed that increase in restriction site accessibility correlates with transcriptional activation, which parallels the RA-induced in vivo footprint of the promoter. Despite these changes, the micrococcal nuclease digestion profile of this promoter was not altered by RA. These results indicate that concurrent with the binding of the RXR-RAR heterodimer to the RARE, the local chromatin structure undergoes dynamic, reversible changes in and around the promoter without globally affecting the nucleosomal organization. PMID:9343411

Bhattacharyya, N; Dey, A; Minucci, S; Zimmer, A; John, S; Hager, G; Ozato, K

1997-01-01

242

Requirements for Peptide-induced T Cell Receptor Downregulation on Naive CD8 1 T Cells  

Microsoft Academic Search

Summary The requirements for inducing downregulation of a \\/ b T cell receptor (TCR) molecules on naive major histocompatibility complex class I-restricted T cells was investigated with 2C TCR transgenic mice and defined peptides as antigen. Confirming previous results, activation of 2C T cells in response to specific peptides required CD8 expression on the responder cells and was heavily dependent

Zeling Cai; Hidehiro Kishimoto; Anders Brunmark; Michael R. Jackson; Per A. Peterson; Jonathan Sprent

243

Antipsychotic drug-induced weight gain mediated by histamine H1 receptor-linked activation  

E-print Network

Antipsychotic drug-induced weight gain mediated by histamine H1 receptor-linked activation, December 21, 2006 (sent for review November 28, 2006) The atypical antipsychotic drugs (AAPDs) have intake. atypical antipsychotic drugs obesity hypothalamus The antipsychotic actions of classic

Kim, Sangwon F.

244

Distinct ADAM Metalloproteinases Regulate G Protein-coupled Receptor-induced Cell Proliferation and Survival*  

E-print Network

of metalloproteinases of the ADAM and matrix metalloproteinase families have been implicated in HB-EGF precursorDistinct ADAM Metalloproteinases Regulate G Protein-coupled Receptor-induced Cell Proliferation. Here, we demon- strate that the EGFR transactivation signal requires metalloproteinase cleavage

Ullrich, Axel

245

MECHANISMS OF ZN-INDUCED SIGNAL INITIATION THROUGH THE EPIDERMAL GROWTH FACTOR RECEPTOR (EGFR)  

EPA Science Inventory

MECHANISMS OF Zn-INDUCED SIGNAL INITIATION THROUGH THE EPIDERMAL GROWTH FACTOR RECEPTOR (EGFR) James M. Samet*, Lee M. Graves? and Weidong Wu?. *Human Studies Division, NHEERL, ORD, Research Triangle Park, NC 27711, and ?Center for Environmental Medicine, University of North C...

246

Adenosine A3 receptor stimulation induces protection of skeletal muscle from eccentric exercise-mediated injury  

E-print Network

Adenosine A3 receptor stimulation induces protection of skeletal muscle from eccentric exercise of skeletal muscle from eccentric exercise-mediated injury. Am J Physiol Regul Integr Comp Physiol 299: R259­R267, 2010. First published April 28, 2010; doi:10.1152/ajpregu.00060.2010.--Effective therapy

Campbell, Kevin P.

247

Peroxisome Proliferator-Activated Receptor Protects Against Alcohol-Induced Liver Damage  

E-print Network

Peroxisome Proliferator-Activated Receptor Protects Against Alcohol-Induced Liver Damage Tamie alcoholic liver disease are not completely understood, but lipid accumulation seems to be central. To investi- gate the roles of PPAR in alcoholic liver injury, wild-type and PPAR -null mice were continuously

Omiecinski, Curtis

248

Could hormone-induced loss of gonadotrophin receptors reduce the efficiency of superovulations stimulated by PMSG ?  

E-print Network

Could hormone-induced loss of gonadotrophin receptors reduce the efficiency of superovulations, 1976 ; Seidel et al., 1978). Pituitary follicle stimulating hormone (FSH) is unlikely to be ever, as well as FSH activity, it also acts as a luteinizing or interstitial cell stimulating hormone (Papkoff

Boyer, Edmond

249

Phototropin Blue Light Receptors and Light-Induced Movement Responses in Plants  

NSDL National Science Digital Library

Two blue light receptors in Arabidopsis, termed phot1 and phot2, which contain flavin chromophores and have intrinsic protein kinase activity, participate in several physiological processes. Lin looks at the genetic evidence regarding how these photoreceptors mediate blue light-induced phototropism, chloroplast relocalization, and opening of the stomatal aperture.

Chentao Lin (University of California at Los Angeles;Department of Molecular, Cell and Developmental Biology REV)

2002-02-05

250

Activation of spinal cannabinoid CB2 receptors inhibits neuropathic pain in streptozotocin-induced diabetic mice.  

PubMed

The role of spinal cannabinoid systems in neuropathic pain of streptozotocin (STZ)-induced diabetic mice was studied. In normal mice, injection of the cannabinoid receptor agonist WIN-55,212-2 (1 and 3?g, i.t.) dose-dependently prolonged the tail-flick latency, whereas there were no changes with the injection of either cannabinoid CB1 (AM 251, 1 ?g, i.t.) or CB2 (AM 630, 4 ?g, i.t.) receptor antagonists. AM 251 (1 ?g, i.t.), but not AM 630 (4 ?g, i.t.), significantly inhibited the prolongation of the tail-flick latency induced by WIN-55,212-2 (3 ?g, i.t.). In STZ-induced diabetic mice, the tail-flick latency was significantly shorter than that in normal mice. A low dose of WIN-55,212-2 (1 ?g, i.t.) significantly recovered the tail-flick latency in STZ-induced diabetic mice. The effect of WIN-55,212-2 (1 ?g, i.t.) in STZ-induced diabetic mice was significantly inhibited by AM 630 (4 ?g, i.t.), but not AM 251 (1 ?g). The selective cannabinoid CB2 receptor agonist L-759,656 (19 and 38 ?g, i.t.) also dose-dependently recovered the tail-flick latency in STZ-induced diabetic mice, and this recovery was inhibited by AM 630 (4 ?g, i.t.). The protein levels of cannabinoid CB1 receptors, CB2 receptors and diacylglycerol lipase ? (DGL-?), the enzyme that synthesizes endocannabinoid 2-arachidonoylglycerol, in the spinal cord were examined using Western blotting. The protein levels of both cannabinoid CB1 and CB2 receptors were increased in STZ-induced diabetic mice, whereas the protein level of DGL-? was significantly decreased. These results indicate that spinal cannabinoid systems are changed in diabetic mice and suggest that cannabinoid CB2 receptor agonists might have an ability to recover diabetic neuropathic pain. PMID:23892011

Ikeda, H; Ikegami, M; Kai, M; Ohsawa, M; Kamei, J

2013-10-10

251

Aspartame downregulates 3T3-L1 differentiation.  

PubMed

Aspartame is an artificial sweetener used as an alternate for sugar in several foods and beverages. Since aspartame is 200 times sweeter than traditional sugar, it can give the same level of sweetness with less substance, which leads to lower-calorie food intake. There are reports that consumption of aspartame-containing products can help obese people lose weight. However, the potential role of aspartame in obesity is not clear. The present study investigated whether aspartame suppresses 3T3-L1 differentiation, by downregulating phosphorylated peroxisome proliferator-activated receptor ? (p-PPAR?), peroxisome proliferator-activated receptor ? (PPAR?), fatty acid-binding protein 4 (FABP4), CCAAT/enhancer-binding protein ? (C/EBP?), and sterol regulatory element-binding protein 1 (SREBP1), which are critical for adipogenesis. The 3T3-L1 adipocytes were cultured and differentiated for 6 d in the absence and presence of 10 ?g/ml of aspartame. Aspartame reduced lipid accumulation in differentiated adipocytes as evidenced by Oil Red O staining. qRT-PCR analysis showed that the PPAR?, FABP4, and C/EBP? mRNA expression was significantly reduced in the aspartame-treated adipocytes. Western blot analysis showed that the induction of p-PPAR?, PPAR?, SREBP1, and adipsin was markedly reduced in the aspartame-treated adipocytes. Taken together, these data suggest that aspartame may be a potent substance to alter adipocyte differentiation and control obesity. PMID:24961835

Pandurangan, Muthuraman; Park, Jeongeun; Kim, Eunjung

2014-10-01

252

Hypoxia Attenuates Purinergic P2X Receptor-Induced Inflammatory Gene Expression in Brainstem Microglia  

PubMed Central

Hypoxia and increased extracellular nucleotides are frequently coincident in the brainstem. Extracellular nucleotides are potent modulators of microglial inflammatory gene expression via P2X purinergic receptor activation. Although hypoxia is also known to modulate inflammatory gene expression, little is known about how hypoxia or P2X receptor activation alone affect inflammatory molecule production in brainstem microglia, nor how hypoxia and P2X receptor signaling interact when they occur together. In this study, we investigated the ability of a brief episode of hypoxia (2hrs) in the presence and absence of the non-selective P2X receptor agonist 2?(3?)-O-(4-benzoylbenzoyl)adenosine-5?-triphosphate (BzATP) to promote inflammatory gene expression in brainstem microglia in adult rats. We evaluated inducible nitric oxide synthase (iNOS), tumor necrosis factor alpha (TNF?) and interleukin-6 (IL-6) mRNA levels in immunomagnetically-isolated brainstem microglia. Whereas iNOS and IL-6 gene expression increased with hypoxia and BzATP alone, TNF? expression was unaffected. Surprisingly, BzATP-induced inflammatory effects are lost after hypoxia, suggesting that hypoxia impairs pro-inflammatory P2X receptor signaling. We also evaluated the expression of key P2X receptors activated by BzATP, namely P2X1, P2X4 and P2X7 receptors. Whereas hypoxia did not alter their expression, BzATP upregulated P2X4 and P2X7 mRNAs; these effects were ablated in hypoxia. Although both P2X4 and P2X7 receptor expression correlated with increased microglial iNOS and IL-6 levels in microglia from normoxic rats, in hypoxia, P2X7 only correlated with IL-6, and P2X4 correlated only with iNOS. In addition, correlations between P2X7 and P2X4 were lost following hypoxia, suggesting that P2X4 and P2X7 receptor signaling differs in normoxia and hypoxia. Together, these data suggest that hypoxia suppresses P2X receptor-induced inflammatory gene expression, indicating a potentially immunosuppressive role of extracellular nucleotides in brainstem microglia following exposure to hypoxia. PMID:24377098

Smith, Stephanie M. C.; Mitchell, Gordon S.; Friedle, Scott A.; Sibigtroth, Christine M.; Vinit, Stéphane; Watters, Jyoti J.

2013-01-01

253

Spurious T3 Thyrotoxicosis Unmasking Multiple Myeloma  

PubMed Central

Objective. To document a case of spurious T3 thyrotoxicosis in a 54-year-old woman. Methods. We present the diagnostic approach of a patient with euthyroid hypertri-iodothyronemia. Results. A 54-year-old, clinically euthyroid woman without personal or family history of thyroid disease referred to endocrinology for possible T3 thyrotoxicosis, after thyroid function tests revealed total T3 > 800?ng/dL (reference range 60–181), normal TSH, and T4. The laboratory data were not compatible with the clinical picture, so thyroid binding globulin abnormalities were suspected. Additional laboratory studies confirmed the diagnosis of multiple myeloma. Conclusion. Monoclonal gammopathy is characterized by the presence of a monoclonal immunoglobulin in the serum or urine, occurring in multiple myeloma, and can cause assay interference and spurious results. We identify a newly recognized cause of euthyroid hypertri-iodothyronemia, due to binding of T3 to monoclonal immunoglobulins in the setting of multiple myeloma. Our case is the only one to date suggesting that monoclonal immunoglobulins from multiple myeloma may exhibit binding to T3 only. PMID:23984117

Antonopoulou, Marianna; Silverberg, Arnold

2013-01-01

254

Morphine-induced antinociception in the rat: supra-additive interactions with imidazoline I? receptor ligands.  

PubMed

Pain remains a significant clinical challenge and currently available analgesics are not adequate to meet clinical needs. Emerging evidence suggests the role of imidazoline I(2) receptors in pain modulation primarily from studies of the non-selective imidazoline receptor ligand, agmatine. However, little is known of the generality of the effect to selective I(2) receptor ligands. This study examined the antinociceptive effects of two selective I(2) receptor ligands 2-BFI and BU224 (>2000-fold selectivity for I(2) receptors over ?(2) adrenoceptors) in a hypertonic (5%) saline-induced writhing test and analyzed their interaction with morphine using a dose-addition analysis. Morphine, 2-BFI and BU224 but not agmatine produced a dose-dependent antinociceptive effect. Both composite additive curve analyses and isobolographical plots revealed a supra-additive interaction between morphine and 2-BFI or BU224, whereas the interaction between 2-BFI and BU224 was additive. The antinociceptive effect of 2-BFI and BU224 was attenuated by the I(2) receptor antagonist/?(2) adrenoceptor antagonist idazoxan but not by the selective ?(2) adrenoceptor antagonist yohimbine, suggesting an I(2) receptor-mediated mechanism. Agmatine enhanced the antinociceptive effect of morphine, 2-BFI and BU224 and the enhancement was prevented by yohimbine, suggesting that the effect was mediated by ?(2) adrenoceptors. Taken together, these data represent the first report that selective I(2) receptor ligands have substantial antinociceptive activity and produce antinociceptive synergy with opioids in a rat model of acute pain. These data suggest that drugs acting on imidazoline I(2) receptors may be useful either alone or in combination with opioids for the treatment of pain. PMID:21867697

Li, Jun-Xu; Zhang, Yanan; Winter, Jerrold C

2011-11-01

255

Hedgehog signalling via a calcitonin receptor-like receptor can induce arterial differentiation independently of VEGF signalling in zebrafish  

PubMed Central

Multiple signalling pathways control the specification of endothelial cells (ECs) to become arteries or veins during vertebrate embryogenesis. Current models propose that a cascade of Hedgehog (Hh), Vascular Endothelial Growth Factor (VEGF) and Notch signalling acts instructively on ECs to control the choice between arterial or venous fate. Differences in the phenotypes induced by Hh, VEGF or Notch inhibition suggest that not all of the effects of Hh on arterial-venous specification, are mediated by VEGF. We establish that full derepression of the Hh pathway in ptc1;ptc2 mutants converts the posterior cardinal vein into a second arterial vessel that manifests intact arterial gene expression, intersegmental vessel sprouting and haematopoietic stem cell (HSC) gene expression. Importantly, whilst VEGF was thought to be absolutely essential for arterial fates, we find that normal and ectopic arterial differentiation can occur without VEGF signalling in ptc1;ptc2 mutants. Furthermore, Hh is able to bypass VEGF to induce arterial differentiation in ECs via the calcitonin receptor-like receptor, thus revealing a surprising complexity in the interplay between Hh and VEGF signalling during arteriovenous specification. Finally, our experiments establish a dual function of Hedgehog during induction of runx1+ HSCs. PMID:22668851

Wilkinson, Robert N.; Koudijs, Marco J.; Patient, Roger K.; Ingham, Philip W.; Schulte-Merker, Stefan; van Eeden, Fredericus J.M.

2013-01-01

256

Echinacea purpurea root extract enhances the adipocyte differentiation of 3T3-L1 cells.  

PubMed

Echinacea purpurea has been shown to have anti-diabetic activities; for example, it activates peroxisome proliferator-activated receptor ? (PPAR?) and increases insulin-stimulated glucose uptake. Adipogenesis has been used to study the insulin signaling pathway and to screen anti-diabetic compounds. The present study was conducted to investigate the effects of an ethanol extract of E. purpurea (EEEP) and its constituents on the insulin-induced adipocyte differentiation of 3T3-L1 preadipocytes. When adipocyte differentiation was induced with insulin plus 3-isobutyl-1-methylxanthine and dexamethasone, the accumulation of lipid droplets and the cellular triglyceride content were significantly increased by EEEP. The expressions of PPAR? and C/EBP? in adipocytes treated with EEEP were gradually increased as compared with control cells. Fat accumulation and triglyceride content of adipocytes treated with dodeca-2(E),4(E)-dienoic acid isobutylamide were significantly increased as compared with control cells. The expressions of PPAR? and C/EBP? in adipocytes treated with dodeca-2(E),4(E)-dienoic acid isobutylamide were significantly higher than in control cells. These results suggest EEEP promotes the adipogenesis that is partially induced by insulin and that dodeca-2(E),4(E)-dienoic acid isobutylamide appears to be responsible for EEEP-enhanced adipocyte differentiation. PMID:24085629

Shin, Dong-Mi; Choi, Kyeong-Mi; Lee, Youn-Sun; Kim, Wonkyun; Shin, Kyong-Oh; Oh, Seikwan; Jung, Jae-Chul; Lee, Mi Kyeong; Lee, Yong-Moon; Hong, Jin Tae; Yun, Yeo-Pyo; Yoo, Hwan-Soo

2014-06-01

257

Histamine 4 receptor plays an important role in auto-antibody-induced arthritis.  

PubMed

Rheumatoid arthritis is a widespread autoimmune disease. In the murine K/B×N arthritis model, anti-GPI (anti-glucose 6-phosphate isomerase) antibodies lead to the formation of immune complexes. In the course of pathogenesis, these complexes activate the immune system and induce degranulation of mast cells, which are essential in this model of rheumatoid arthritis. A major mediator in mast cell granules is histamine, which is proven to be indispensable for joint inflammation in K/B×N mice. Histamine is known to bind to four different receptors (HR1-4), which have different expression profiles and exert a variety of different functions, including activation of the immune system. To analyze the contribution of the different histamine receptors, we employed histamine receptor antagonists (cetirizine, ranitidine, thioperamide and clozapine) blocking the receptors in C57BL/6 mice. Arthritis was induced via K/B×N serum injection. The results demonstrated that mice treated with all four histamine receptor antagonists simultaneously showed no arthritic symptoms, while positive control mice injected with K/B×N serum and vehicle suffered from severe symptoms. When antagonists specific for HR1-4 were applied individually, only the HR4 antagonist clozapine could protect mice from arthritis, reflecting its expression and functionality in the immune system. PMID:23545338

Nent, Elisa; Frommholz, David; Gajda, Mieczyslaw; Bräuer, Rolf; Illges, Harald

2013-07-01

258

Role of direct estrogen receptor signaling in wear particle-induced osteolysis  

PubMed Central

Estrogen withdrawal following surgical ovariectomy was recently shown to mitigate particle-induced osteolysis in the murine calvarial model. Currently, we hypothesize that estrogen receptors (ERs) were involved in this paradoxical phenomenon. To test this hypothesis, we first evaluated polyethylene (PE) particle-induced osteolysis in the murine calvarial model, using wild type (WT) C57BL6J female mice, ER? deficient (ER?KO) mice, and WT mice either treated with 17?-estradiol (E2) or with the ER pan-antagonist ICI 182,780. According to micro-CT and histomorphometry, we showed that bone resorption was consistently altered in both ER?KO and ICI 182,780 treated mice as compared to WT and E2 groups. Then, we demonstrated that ER disruption consistently decreased both PE and polymethylmethacrylate (PMMA) particle-induced production of TNF-? by murine macrophages in vitro. Similar results were obtained following ER blockade using ICI 182,780 in RAW 264.7 and WT macrophages. ER disruption and pre treatment with ICI 182,780 resulted in a consistent down-regulation of particle-induced TNF-? mRNA expression relative to WT macrophages or untreated RAW cells. These results indicate that the response to wear particles involves estrogen receptors in female mice, as part of macrophage activation. Estrogen receptors may be considered as a future therapeutic target for particle-induced osteolysis. PMID:23113918

Nich, Christophe; Rao, Allison J.; Valladares, Roberto D.; Li, Chenguang; Christman, Jane E.; Antonios, Joseph K.; Yao, Zhenyu; Zwingenberger, Stefan; Petite, Hervé; Hamadouche, Moussa; Goodman, Stuart B.

2014-01-01

259

Sigma 1 receptor antagonists determine the behavioral pattern of the methamphetamine-induced stereotypy in mice  

Microsoft Academic Search

Objective  The effects of sigma receptor antagonists on methamphetamine (METH)-induced stereotypy have not been examined. We examined\\u000a the effects of sigma antagonists on METH-induced stereotypy in mice.\\u000a \\u000a \\u000a \\u000a Results  The administration of METH (10 mg\\/kg) to male ddY mice induced stereotyped behavior consisting of biting (90.1%), sniffing\\u000a (4.2%), head bobbing (4.1%), and circling (1.7%) during an observation period of 1 h. Pretreatment of the mice

J. Kitanaka; N. Kitanaka; T. Tatsuta; F. S. Hall; G. R. Uhl; K. Tanaka; N. Nishiyama; Y. Morita; M. Takemura

2009-01-01

260

Select G-protein coupled receptors modulate agonist-induced signaling via a ROCK, LIMK and ?-arrestin 1 pathway  

PubMed Central

G-protein coupled receptors (GPCRs) are typically present in a basal, inactive state, but when bound to agonist they activate downstream signaling cascades. In studying arrestin regulation of opioid receptors in dorsal root ganglia (DRG) neurons, we find that agonists of delta opioid receptors (?ORs) activate cofilin through Rho-associated coiled-coiled containing protein kinase (ROCK), LIM domain kinase (LIMK) and ?- arrestin 1 (?-arr1), to regulate actin polymerization. This controls receptor function, as assessed by agonist-induced inhibition of voltage-dependent Ca2+ channels in DRGs. Agonists of opioid-receptor like receptors (ORL1) similarly influence the function of this receptor through ROCK, LIMK and ?-arr1. Functional evidence of this cascade was demonstrated in vivo where the behavioral effects of ?OR or ORL1 agonists were enhanced in the absence of ?-arr1 or prevented by inhibiting ROCK. This pathway allows ?OR and ORL1 agonists to rapidly regulate receptor function. PMID:24239352

Mittal, Nitish; Roberts, Kristofer; Pal, Katsuri; Bentolila, Laurent A.; Fultz, Elissa; Minasyan, Ani; Cahill, Catherine; Pradhan, Amynah; Conner, David; DeFea, Kathryn; Evans, Christopher; Walwyn, Wendy

2013-01-01

261

Nicotinic acetylcholine receptor desensitization is regulated by activation-induced extracellular adenosine accumulation.  

PubMed

Adenosine modulation of nicotinic ACh receptor (nAChR) function was studied in primary cultures of rat skeletal muscle. Activation of the nAChR by carbachol increased extracellular adenosine concentration in a dose-dependent manner. Furthermore, carbachol activation of the nicotinic receptor resulted in a twofold increase in cAMP levels in the muscle cells. The carbachol-dependent increase in cAMP levels was inhibited by adenosine receptor antagonists as well as by nicotinic receptor antagonists. These results suggest that the increased cAMP levels were due to adenosine receptor activation by the extracellular adenosine accumulated on nAChR activation. Others have shown that desensitization of the nAChR by agonist is mediated, in part, by phosphorylation. Since we found that nicotinic cholinergic agonists also cause adenosine accumulation with concomitant cAMP increases, we determined whether the accumulated adenosine has a role in desensitization. We found that the adenosine receptor antagonist, BW1434U, significantly inhibited carbachol-induced nAChR desensitization, indicating that extracellular adenosine is involved in nAChR desensitization. Our data suggest that nAChR function is regulated via a feedback mechanism mediated by adenosine released from muscle on activation of the nAChR. PMID:1331363

Pitchford, S; Day, J W; Gordon, A; Mochly-Rosen, D

1992-11-01

262

SN79, a sigma receptor ligand, blocks methamphetamine-induced microglial activation and cytokine upregulation.  

PubMed

Methamphetamine (METH) abuse is associated with several negative side effects including neurotoxicity in specific brain regions such as the striatum. The precise molecular mechanisms by which METH usage results in neurotoxicity remain to be fully elucidated, with recent evidence implicating the importance of microglial activation and neuroinflammation in damaged brain regions. METH interacts with sigma receptors which are found in glial cells in addition to neurons. Moreover, sigma receptor antagonists have been shown to block METH-induced neurotoxicity in rodents although the cellular mechanisms underlying their neuroprotection remain unknown. The purpose of the current study was to determine if the prototypic sigma receptor antagonist, SN79, mitigates METH-induced microglial activation and associated increases in cytokine expression in a rodent model of METH-induced neurotoxicity. METH increased striatal mRNA and protein levels of cluster of differentiation 68 (CD68), indicative of microglial activation. METH also increased ionized calcium binding adapter molecule 1 (IBA-1) protein expression, further confirming the activation of microglia. Along with microglial activation, METH increased striatal mRNA expression levels of IL-6 family pro-inflammatory cytokines, leukemia inhibitory factor (lif), oncostatin m (osm), and interleukin-6 (il-6). Pretreatment with SN79 reduced METH-induced increases in CD68 and IBA-1 expression, demonstrating its ability to prevent microglial activation. SN79 also attenuated METH-induced mRNA increases in IL-6 pro-inflammatory cytokine family members. The ability of a sigma receptor antagonist to block METH-induced microglial activation and cytokine production provides a novel mechanism through which the neurotoxic effects of METH may be mitigated. PMID:23631864

Robson, Matthew J; Turner, Ryan C; Naser, Zachary J; McCurdy, Christopher R; Huber, Jason D; Matsumoto, Rae R

2013-09-01

263

SN79, a sigma receptor ligand, blocks methamphetamine-induced microglial activation and cytokine upregulation  

PubMed Central

Methamphetamine (METH) abuse is associated with several negative side effects including neurotoxicity in specific brain regions such as the striatum. The precise molecular mechanisms by which METH usage results in neurotoxicity remain to be fully elucidated, with recent evidence implicating the importance of microglial activation and neuroinflammation in damaged brain regions. METH interacts with sigma receptors which are found in glial cells in addition to neurons. Moreover, sigma receptor antagonists have been shown to block METH-induced neurotoxicity in rodents although the cellular mechanisms underlying their neuroprotection remain unknown. The purpose of the current study was to determine if the prototypic sigma receptor antagonist, SN79, mitigates METH-induced microglial activation and associated increases in cytokine expression in a rodent model of METH-induced neurotoxicity. METH increased striatal mRNA and protein levels of cluster of differentiation 68 (CD68), indicative of microglial activation. METH also increased ionized calcium binding adapter molecule 1 (IBA-1) protein expression, further confirming the activation of microglia. Along with microglial activation, METH increased striatal mRNA expression levels of IL-6 family pro-inflammatory cytokines, leukemia inhibitory factor (lif), oncostatin m (osm), and interleukin-6 (il-6). Pretreatment with SN79 reduced METH-induced increases in CD68 and IBA-1 expression, demonstrating its ability to prevent microglial activation. SN79 also attenuated METH-induced mRNA increases in IL-6 pro-inflammatory cytokine family members. The ability of a sigma receptor antagonist to block METH-induced microglial activation and cytokine production provides a novel mechanism through which the neurotoxic effects of METH may be mitigated. PMID:23631864

Robson, Matthew J.; Turner, Ryan C.; Naser, Zachary J.; McCurdy, Christopher R.; Huber, Jason D.; Matsumoto, Rae R.

2013-01-01

264

Prevention of Paclitaxel-Induced Neuropathy Through Activation of the Central Cannabinoid Type 2 Receptor System  

PubMed Central

Background Peripheral neuropathy is a major dose-limiting toxicity of chemotherapy, especially after multiple courses of paclitaxel. The development of paclitaxel-induced neuropathy is associated with the activation of microglia followed by the activation and proliferation of astrocytes, and the expression and release of proinflammatory cytokines in the spinal dorsal horn. Cannabinoid type 2 (CB2) receptors are expressed in the microglia in neurodegenerative disease models. Methods To explore the potential of CB2 agonists for preventing paclitaxel-induced neuropathy, we designed and synthesized a novel CB2-selective agonist, namely MDA7. The effect of MDA7 in preventing paclitaxel-induced allodynia was assessed in rats and in CB2+/+ and CB2–/– mice. We hypothesize that the CB2 receptor functions in a negative-feedback loop and that early MDA7 administration can blunt the neuroinflammatory response to paclitaxel and prevent mechanical allodynia through interference with specific signaling pathways. Results We found that MDA7 prevents paclitaxel-induced mechanical allodynia in rats and mice in a dose- and time-dependent manner without compromising paclitaxel's antineoplastic effect. MDA7's neuroprotective effect was absent in CB2-/- mice and was blocked by CB2 antagonists, suggesting that MDA7's action directly involves CB2 receptor activation. MDA7 treatment was found to interfere with early events in the paclitaxel-induced neuroinflammatory response as evidenced by relatively reduced Toll-like receptor and CB2 expression in the lumbar spinal cord, reduced levels of extracellular signal regulated kinase 1/2 activity, reduced numbers of activated microglia and astrocytes, and reduced secretion of proinflammatory mediators in vivo and in in vitro models. Conclusions Our findings suggest an innovative therapeutic approach to prevent chemotherapy-induced neuropathy and may permit more aggressive use of active chemotherapeutic regimens with reduced long-term sequelae. PMID:22392969

Naguib, Mohamed; Xu, Jijun J.; Diaz, Philippe; Brown, David L.; Cogdell, David; Bie, Bihua; Hu, Jianhua; Craig, Suzanne; Hittelman, Walter N.

2012-01-01

265

Nociceptin/orphanin FQ receptor activation decreases the airway hyperresponsiveness induced by allergen in sensitized mice.  

PubMed

Several studies suggest that the N/OFQ (nociceptin/orphanin FQ)-NOP (N/OFQ peptide) receptor pathway is involved in airway physiology. We previously demonstrated a modulation of the endogenous N/OFQ levels in allergen-sensitized mice. Here, we investigated the effects of NOP receptor activation in allergen sensitization using a murine model of allergen-induced airway hyperresponsiveness (AHR). BALB/c mice were intraperitoneally treated with the NOP receptor agonist UFP-112, either during the sensitization phase (30 min before ovalbumin administration) or at the end of sensitization process (15 min before bronchopulmonary reactivity evaluation). At day 21 from the first allergen exposure, bronchopulmonary reactivity and total and differential cell count in bronchoalveolar lavage fluid were evaluated. In a separate set of experiments cell proliferation in lymphocytes, cytokine levels, IgE serum levels, and the effect of UFP-112 on IL-13-induced AHR were evaluated. Pretreatment with UFP-112, during the sensitization phase, caused a significant reduction in allergen-induced AHR and total cell lung infiltration. No effect on allergen-induced AHR was observed when the treatment was performed at the end of sensitization process, on tissues harvested from OVA-sensitized mice and on IL-13-induced AHR. The in vitro proliferative response of lymphocytes was significantly reduced by pretreatment during the sensitization phase with UFP-112. This effect was paralleled by a significant modulation of cytokine secretion in pulmonary tissues and lymphocytes. In conclusion, we demonstrated a role for the NOP receptor and N/OFQ pathway in the AHR induced by allergen, probably through a modulation of the immune response that triggers the development of AHR that involves pro- and anti-inflammatory cytokines. PMID:23502511

Sullo, Nikol; Roviezzo, Fiorentina; Matteis, Maria; Ianaro, Angela; Calò, Girolamo; Guerrini, Remo; De Gruttola, Luana; Spaziano, Giuseppe; Cirino, Giuseppe; Rossi, Francesco; D'Agostino, Bruno

2013-05-15

266

Activation of D1 dopamine receptors induces emergence from isoflurane general anesthesia  

PubMed Central

BACKGROUND A recent study showed that methylphenidate induces emergence from isoflurane anesthesia. Methylphenidate inhibits dopamine and norepinephrine reuptake transporters. The objective of this study was to test the hypothesis that selective dopamine receptor activation induces emergence from isoflurane anesthesia. METHODS In adult rats, we tested the effects of chloro-APB (D1 agonist) and quinpirole (D2 agonist) on time to emergence from isoflurane general anesthesia. We then performed a dose–response study to test for chloro-APB-induced restoration of righting during continuous isoflurane anesthesia. SCH-23390 (D1 antagonist) was used to confirm that the effects induced by chloro-APB are specifically mediated by D1 receptors. In a separate group of animals, spectral analysis was performed on surface electroencephalogram recordings to assess neurophysiological changes induced by chloro-APB and quinpirole during isoflurane general anesthesia. RESULTS Chloro-APB decreased median time to emergence from 330s to 50s. The median difference in time to emergence between the saline control group (n=6) and the chloro-APB group (n = 6) was 222s (95% CI: 77–534s, Mann-Whitney test). This difference was statistically significant (p = 0.0082). During continuous isoflurane anesthesia, chloro-APB dose-dependently restored righting (n = 6) and decreased electroencephalogram delta power (n = 4). These effects were inhibited by pretreatment with SCH-23390. Quinpirole did not restore righting (n = 6) and had no significant effect on the electroencephalogram (n = 4) during continuous isoflurane anesthesia. CONCLUSIONS Activation of D1 receptors by chloro-APB decreases time to emergence from isoflurane anesthesia, and produces behavioral and neurophysiological evidence of arousal during continuous isoflurane anesthesia. These findings suggest that selective activation of a D1 receptor-mediated arousal mechanism is sufficient to induce emergence from isoflurane general anesthesia. PMID:23221866

Taylor, Norman E.; Chemali, Jessica J.; Brown, Emery N.; Solt, Ken

2012-01-01

267

Depolarization induces a conformational change in the binding site region of the M2 muscarinic receptor.  

PubMed

G protein-coupled receptors play a central role in signal transduction and were only known to be activated by agonists. Recently it has been shown that membrane potential also affects the activity of G protein-coupled receptors. For the M(2) muscarinic receptor, it was further shown that depolarization induces charge movement. A tight correlation was found between the voltage-dependence of the charge movement and the voltage-dependence of the agonist binding. Here we examine whether depolarization-induced charge movement causes a conformational change in the M(2) receptor that may be responsible for the voltage-dependence of agonist binding. Using site-directed fluorescence labeling we show a voltage-dependent fluorescence signal, reflecting a conformational change, which correlates with the voltage-dependent charge movement. We further show that selected mutations in the orthosteric site abolish the fluorescence signal and concomitantly, the voltage-dependence of the agonist binding. Surprisingly, mutations in the allosteric site also abolished the voltage-dependence of agonist binding but did not reduce the fluorescence signal. Finally, we show that treatments, which reduced the charge movement or hindered the coupling between the charge movement and the voltage-dependent binding, also reduced the fluorescence signal. Our results demonstrate that depolarization-induced conformational changes in the orthosteric binding site underlie the voltage-dependence of agonist binding. Our results are also unique in suggesting that the allosteric site is also involved in controlling the voltage-dependent agonist binding. PMID:22184214

Dekel, Noa; Priest, Michael F; Parnas, Hanna; Parnas, Itzchak; Bezanilla, Francisco

2012-01-01

268

A putative role for hypothalamic glucocorticoid receptors in hypertension induced by prenatal undernutrition in the rat.  

PubMed

Prenatal undernutrition induces hypertension later in life, possibly by disturbing the hypothalamo-pituitary-adrenal axis through programming decreased expression of hypothalamic glucocorticoid receptors. We examined the systolic blood pressure, heart rate and plasma corticosterone response to intra-paraventricular dexamethasone, mifepristone and corticosterone in eutrophic and prenatally undernourished young rats. Undernutrition was induced during fetal life by restricting the diet of pregnant mothers to 10 g daily (40% of diet consumed by well-nourished controls). At day 40 of postnatal life (i) intra-paraventricular administration of dexamethasone significantly reduced at least for 24h both the systolic pressure (-11.6%), the heart rate (-20.8%) and the plasma corticosterone (-40.0%) in normal animals, while producing lower effects (-5.5, -8.7, and -22.3%, respectively) on undernourished rats; (ii) intra-paraventricular administration of the antiglucocorticoid receptor ligand mifepristone to normal rats produced opposite effects (8.2, 20.3, and 48.0% increase, respectively) to those induced by dexamethasone, being these not significant in undernourished animals; (iii) intra-paraventricular corticosterone did not exert any significant effect. Results suggest that the low sensitivity of paraventricular neurons to glucocorticoid receptor ligands observed in prenatally undernourished rats could be due to the already reported glucocorticoid receptor expression, found in the hypothalamus of undernourished animals. PMID:20674672

Pérez, Hernán; Soto-Moyano, Rubén; Ruiz, Samuel; Hernández, Alejandro; Sierralta, Walter; Olivares, Ricardo; Núñez, Héctor; Flores, Osvaldo; Morgan, Carlos; Valladares, Luis; Gatica, Arnaldo; Flores, Francisco J

2010-10-01

269

ABCD2 alters peroxisome proliferator-activated receptor ? signaling in vitro, but does not impair responses to fenofibrate therapy in a mouse model of diet-induced obesity.  

PubMed

Fenofibrate is a peroxisome proliferator-activated receptor (PPAR) ? ligand that has been widely used as a lipid-lowering agent in the treatment of hypertriglyceridemia. ABCD2 (D2) is a peroxisomal long-chain acyl-CoA transporter that is highly induced by fenofibrate in the livers of mice. To determine whether D2 is a modifier of fibrate responses, wild-type and D2-deficient mice were treated with fenofibrate for 14 days. The absence of D2 altered expression of gene clusters associated with lipid metabolism, including PPAR? signaling. Using 3T3-L1 adipocytes, which express high levels of D2, we confirmed that knockdown of D2 modified genomic responses to fibrate treatment. We next evaluated the impact of D2 on effects of fibrates in a mouse model of diet-induced obesity. Fenofibrate treatment opposed the development of obesity, hypertriglyceridemia, and insulin resistance. However, these effects were unaffected by D2 genotype. We concluded that D2 can modulate genomic responses to fibrates, but that these effects are not sufficiently robust to alter the effects of fibrates on diet-induced obesity phenotypes. PMID:25123288

Liu, Xiaoxi; Liu, Jingjing; Liang, Shuang; Schlüter, Agatha; Fourcade, Stephane; Aslibekyan, Stella; Pujol, Aurora; Graf, Gregory A

2014-11-01

270

Neurosteroid Agonist at GABAA Receptor Induces Persistent Neuroplasticity in VTA Dopamine Neurons  

PubMed Central

The main fast-acting inhibitory receptors in the mammalian brain are ?-aminobutyric acid type-A (GABAA) receptors for which neurosteroids, a subclass of steroids synthesized de novo in the brain, constitute a group of endogenous ligands with the most potent positive modulatory actions known. Neurosteroids can act on all subtypes of GABAA receptors, with a preference for ?-subunit-containing receptors that mediate extrasynaptic tonic inhibition. Pathological conditions characterized by emotional and motivational disturbances are often associated with perturbation in the levels of endogenous neurosteroids. We studied the effects of ganaxolone (GAN)—a synthetic analog of endogenous allopregnanolone that lacks activity on nuclear steroid receptors—on the mesolimbic dopamine (DA) system involved in emotions and motivation. A single dose of GAN in young mice induced a dose-dependent, long-lasting neuroplasticity of glutamate synapses of DA neurons ex vivo in the ventral tegmental area (VTA). Increased ?-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA)/N-methyl-D-aspartate ratio and rectification of AMPA receptor responses even at 6 days after GAN administration suggested persistent synaptic targeting of GluA2-lacking AMPA receptors. This glutamate neuroplasticity was not observed in GABAA receptor ?-subunit-knockout (?-KO) mice. GAN (500?nM) applied locally to VTA selectively increased tonic inhibition of GABA interneurons and triggered potentiation of DA neurons within 4?h in vitro. Place-conditioning experiments in adult wild-type C57BL/6J and ?-KO mice revealed aversive properties of repeated GAN administration that were dependent on the ?-subunits. Prolonged neuroadaptation to neurosteroids in the VTA might contribute to both the physiology and pathophysiology underlying processes and changes in motivation, mood, cognition, and drug addiction. PMID:24077066

Vashchinkina, Elena; Manner, Aino K; Vekovischeva, Olga; Hollander, Bjørnar den; Uusi-Oukari, Mikko; Aitta-aho, Teemu; Korpi, Esa R

2014-01-01

271

Expression of E-series prostaglandin (EP) receptors and urodynamic effects of an EP4 receptor antagonist on cyclophosphamide-induced overactive bladder in rats  

PubMed Central

OBJECTIVE To investigate the expression of four subtypes of E-series prostaglandin (EP1–EP4) receptors and the urodynamic effects of an EP4 receptor antagonist (AH23848) in cyclophosphamide (CYP)-induced overactive bladder (OAB) in rats, as intravesical prostaglandin E2 (PGE2) induces OAB via activation of EP receptors and sensitization of afferent nerves. MATERIALS AND METHODS Experimental and control rats were injected with CYP (200 mg/kg, intraperitoneally) or saline, respectively. Continuous cystometrograms (CMGs) were performed 48 h after CYP or saline injection under urethane anaesthesia. AH23848 was given intravenously at doses of 0.01 and 0.1 mg/kg. The bladder was then harvested for histology. Some bladders were harvested for analysis of EP receptors expression by Western blotting without a CMG study. CMG variables (baseline pressure; intercontraction interval [ICI], pressure threshold [PT], contraction amplitude) and histological changes were measured. RESULTS CYP-induced up-regulation of EP4 receptor (100% increase) accompanied by detrusor overactivity (ICI 70.5% decrease; PT, 67.7% increase). However, CYP down-regulated EP1 receptor expression (51.9% decrease), but had no significant effects on the EP2 and EP3 receptors. AH23848 significantly extended the ICI in CYP-treated rats but it had no effects on other urodynamic variables or in control rats. CONCLUSIONS Modulation of EP receptors plays a role in CYP-induced OAB. Antagonists to the EP4 receptor may be a new target for treatment of patients with OAB. PMID:20346049

Chuang, Yao-Chi; Yoshimura, Naoki; Huang, Chao-Cheng; Wu, Moya; Tyagi, Pradeep; Chancellor, Michael B.

2011-01-01

272

delta-Opioid receptor antagonism induces NMDA receptor-dependent excitotoxicity in anoxic turtle cortex.  

PubMed

delta-Opioid receptor (DOR) activation is neuroprotective against short-term anoxic insults in the mammalian brain. This protection may be conferred by inhibition of N-methyl-d-aspartate receptors (NMDARs), whose over-activation during anoxia otherwise leads to a deleterious accumulation of cytosolic calcium ([Ca(2+)](c)), severe membrane potential (E(m)) depolarization and excitotoxic cell death (ECD). Conversely, NMDAR activity is decreased by approximately 50% with anoxia in the cortex of the painted turtle, and large elevations in [Ca(2+)](c), severe E(m) depolarization and ECD are avoided. DORs are expressed in high quantity throughout the turtle brain relative to the mammalian brain; however, the role of DORs in anoxic NMDAR regulation has not been investigated in turtles. We examined the effect of DOR blockade with naltrindole (1-10 micromol l(-1)) on E(m), NMDAR activity and [Ca(2+)](c) homeostasis in turtle cortical neurons during normoxia and the transition to anoxia. Naltrindole potentiated normoxic NMDAR currents by 78+/-5% and increased [Ca(2+)](c) by 13+/-4%. Anoxic neurons treated with naltrindole were strongly depolarized, NMDAR currents were potentiated by 70+/-15%, and [Ca(2+)](c) increased 5-fold compared with anoxic controls. Following naltrindole washout, E(m) remained depolarized and [Ca(2+)](c) became further elevated in all neurons. The naltrindole-mediated depolarization and increased [Ca(2+)](c) were prevented by NMDAR antagonism or by perfusion of the G(i) protein agonist mastoparan-7, which also reversed the naltrindole-mediated potentiation of NMDAR currents. Together, these data suggest that DORs mediate NMDAR activity in a G(i)-dependent manner and prevent deleterious NMDAR-mediated [Ca(2+)](c) influx during anoxic insults in the turtle cortex. PMID:18931323

Pamenter, Matthew E; Buck, Leslie T

2008-11-01

273

A Cray T3D performance study  

SciTech Connect

We carry out a performance study using the Cray T3D parallel supercomputer to illustrate some important features of this machine. Timing experiments show the speed of various basic operations while more complicated operations give some measure of its parallel performance.

Nallana, A. [Interact, Inc., Austin, TX (United States); Kincaid, D.R. [Texas Univ., Austin, TX (United States)

1996-05-01

274

Obese Mice Lacking Inducible Nitric Oxide Synthase Are Sensitized to the Metabolic Actions of Peroxisome Proliferator–Activated Receptor-? Agonism  

PubMed Central

OBJECTIVE—Synthetic ligands for peroxisome proliferator–activated receptor-? (PPAR-?) improve insulin sensitivity in obesity, but it is still unclear whether inflammatory signals modulate their metabolic actions. In this study, we tested whether targeted disruption of inducible nitric oxide (NO) synthase (iNOS), a key inflammatory mediator in obesity, modulates the metabolic effects of rosiglitazone in obese mice. RESEARCH DESIGN AND METHODS—iNOS?/? and iNOS+/+ were subjected to a high-fat diet or standard diet for 18 weeks and were then treated with rosiglitazone for 2 weeks. Whole-body insulin sensitivity and glucose tolerance were determined and metabolic tissues harvested to assess activation of insulin and AMP-activated protein kinase (AMPK) signaling pathways and the levels of inflammatory mediators. RESULTS—Rosiglitazone was found to similarly improve whole-body insulin sensitivity and insulin signaling to Akt/PKB in skeletal muscle of obese iNOS?/? and obese iNOS+/+ mice. However, rosiglitazone further improved glucose tolerance and liver insulin signaling only in obese mice lacking iNOS. This genotype-specific effect of rosiglitazone on glucose tolerance was linked to a markedly increased ability of the drug to raise plasma adiponectin levels. Accordingly, rosiglitazone increased AMPK activation in muscle and liver only in obese iNOS?/? mice. PPAR-? transcriptional activity was increased in adipose tissue of iNOS?/? mice. Conversely, treatment of 3T3-L1 adipocytes with a NO donor blunted PPAR-? activity. CONCLUSIONS—Our results identify the iNOS/NO pathway as a critical modulator of PPAR-? activation and circulating adiponectin levels and show that invalidation of this key inflammatory mediator improves the efficacy of PPAR-? agonism in an animal model of obesity and insulin resistance. PMID:18458147

Dallaire, Patrice; Bellmann, Kerstin; Laplante, Mathieu; Gélinas, Stéphanie; Centeno-Baez, Carolina; Penfornis, Patrice; Peyot, Marie-Line; Latour, Martin G.; Lamontagne, Julien; Trujillo, Maria E.; Scherer, Philipp E.; Prentki, Marc; Deshaies, Yves; Marette, André

2008-01-01

275

An Antibody Blocking Activin Type II Receptors Induces Strong Skeletal Muscle Hypertrophy and Protects from Atrophy  

PubMed Central

The myostatin/activin type II receptor (ActRII) pathway has been identified to be critical in regulating skeletal muscle size. Several other ligands, including GDF11 and the activins, signal through this pathway, suggesting that the ActRII receptors are major regulatory nodes in the regulation of muscle mass. We have developed a novel, human anti-ActRII antibody (bimagrumab, or BYM338) to prevent binding of ligands to the receptors and thus inhibit downstream signaling. BYM338 enhances differentiation of primary human skeletal myoblasts and counteracts the inhibition of differentiation induced by myostatin or activin A. BYM338 prevents myostatin- or activin A-induced atrophy through inhibition of Smad2/3 phosphorylation, thus sparing the myosin heavy chain from degradation. BYM338 dramatically increases skeletal muscle mass in mice, beyond sole inhibition of myostatin, detected by comparing the antibody with a myostatin inhibitor. A mouse version of the antibody induces enhanced muscle hypertrophy in myostatin mutant mice, further confirming a beneficial effect on muscle growth beyond myostatin inhibition alone through blockade of ActRII ligands. BYM338 protects muscles from glucocorticoid-induced atrophy and weakness via prevention of muscle and tetanic force losses. These data highlight the compelling therapeutic potential of BYM338 for the treatment of skeletal muscle atrophy and weakness in multiple settings. PMID:24298022

Minetti, Giulia C.; Sheppard, KellyAnn; Ibebunjo, Chikwendu; Feige, Jerome N.; Hartmann, Steffen; Brachat, Sophie; Rivet, Helene; Koelbing, Claudia; Morvan, Frederic; Hatakeyama, Shinji

2014-01-01

276

An antibody blocking activin type II receptors induces strong skeletal muscle hypertrophy and protects from atrophy.  

PubMed

The myostatin/activin type II receptor (ActRII) pathway has been identified to be critical in regulating skeletal muscle size. Several other ligands, including GDF11 and the activins, signal through this pathway, suggesting that the ActRII receptors are major regulatory nodes in the regulation of muscle mass. We have developed a novel, human anti-ActRII antibody (bimagrumab, or BYM338) to prevent binding of ligands to the receptors and thus inhibit downstream signaling. BYM338 enhances differentiation of primary human skeletal myoblasts and counteracts the inhibition of differentiation induced by myostatin or activin A. BYM338 prevents myostatin- or activin A-induced atrophy through inhibition of Smad2/3 phosphorylation, thus sparing the myosin heavy chain from degradation. BYM338 dramatically increases skeletal muscle mass in mice, beyond sole inhibition of myostatin, detected by comparing the antibody with a myostatin inhibitor. A mouse version of the antibody induces enhanced muscle hypertrophy in myostatin mutant mice, further confirming a beneficial effect on muscle growth beyond myostatin inhibition alone through blockade of ActRII ligands. BYM338 protects muscles from glucocorticoid-induced atrophy and weakness via prevention of muscle and tetanic force losses. These data highlight the compelling therapeutic potential of BYM338 for the treatment of skeletal muscle atrophy and weakness in multiple settings. PMID:24298022

Lach-Trifilieff, Estelle; Minetti, Giulia C; Sheppard, KellyAnn; Ibebunjo, Chikwendu; Feige, Jerome N; Hartmann, Steffen; Brachat, Sophie; Rivet, Helene; Koelbing, Claudia; Morvan, Frederic; Hatakeyama, Shinji; Glass, David J

2014-02-01

277

T3DB: the toxic exposome database.  

PubMed

The exposome is defined as the totality of all human environmental exposures from conception to death. It is often regarded as the complement to the genome, with the interaction between the exposome and the genome ultimately determining one's phenotype. The 'toxic exposome' is the complete collection of chronically or acutely toxic compounds to which humans can be exposed. Considerable interest in defining the toxic exposome has been spurred on by the realization that most human injuries, deaths and diseases are directly or indirectly caused by toxic substances found in the air, water, food, home or workplace. The Toxin-Toxin-Target Database (T3DB - www.t3db.ca) is a resource that was specifically designed to capture information about the toxic exposome. Originally released in 2010, the first version of T3DB contained data on nearly 2900 common toxic substances along with detailed information on their chemical properties, descriptions, targets, toxic effects, toxicity thresholds, sequences (for both targets and toxins), mechanisms and references. To more closely align itself with the needs of epidemiologists, toxicologists and exposome scientists, the latest release of T3DB has been substantially upgraded to include many more compounds (>3600), targets (>2000) and gene expression datasets (>15 000 genes). It now includes extensive data on 'normal' toxic compound concentrations in human biofluids as well as detailed chemical taxonomies, informative chemical ontologies and a large number of referential NMR, MS/MS and GC-MS spectra. This manuscript describes the most recent update to the T3DB, which was previously featured in the 2010 NAR Database Issue. PMID:25378312

Wishart, David; Arndt, David; Pon, Allison; Sajed, Tanvir; Guo, An Chi; Djoumbou, Yannick; Knox, Craig; Wilson, Michael; Liang, Yongjie; Grant, Jason; Liu, Yifeng; Goldansaz, Seyed Ali; Rappaport, Stephen M

2015-01-28

278

The aryl hydrocarbon receptor mediates raloxifene-induced apoptosis in estrogen receptor-negative hepatoma and breast cancer cells  

PubMed Central

Identification of new molecular targets for the treatment of breast cancer is an important clinical goal, especially for triple-negative breast cancer, which is refractory to existing targeted treatments. The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor known primarily as the mediator of dioxin toxicity. However, the AhR can also inhibit cellular proliferation in a ligand-dependent manner and act as a tumor suppressor in mice, and thus may be a potential anticancer target. To investigate the AhR as an anticancer target, we conducted a small molecule screen to discover novel AhR ligands with anticancer properties. We identified raloxifene, a selective estrogen receptor (ER) modulator currently used in the clinic for prevention of ER-positive breast cancer and osteoporosis in post-menopausal women, as an AhR activator. Raloxifene directly bound the AhR and induced apoptosis in ER-negative mouse and human hepatoma cells in an AhR-dependent manner, indicating that the AhR is a molecular target of raloxifene and mediates raloxifene-induced apoptosis in the absence of ER. Raloxifene selectively induced apoptosis of triple-negative MDA-MB-231 breast cancer cells compared with non-transformed mammary epithelial cells via the AhR. Combined with recent data showing that raloxifene inhibits triple-negative breast cancer xenografts in vivo (Int J Oncol. 43(3):785-92, 2013), our results support the possibility of repurposing of raloxifene as an AhR-targeted therapeutic for triple-negative breast cancer patients. To this end, we also evaluated the role of AhR expression on survival of patients diagnosed with breast cancer. We found that higher expression of the AhR is significantly associated with increased overall survival and distant metastasis-free survival in both hormone-dependent (ER-positive) and hormone-independent (ER and progesterone receptor (PR)-negative) breast cancers. Together, our data strongly support the possibility of using the AhR as a molecular target for the treatment of hormone-independent breast cancers. PMID:24481452

O'Donnell, E F; Koch, D C; Bisson, W H; Jang, H S; Kolluri, S K

2014-01-01

279

IgG Receptor Fc?RIIB Plays a Key Role in Obesity-Induced Hypertension.  

PubMed

There is a well-recognized association between obesity, inflammation, and hypertension. Why obesity causes hypertension is poorly understood. We previously demonstrated using a C-reactive protein (CRP) transgenic mouse that CRP induces hypertension that is related to NO deficiency. Our prior work in cultured endothelial cells identified the Fc? receptor IIB (Fc?RIIB) as the receptor for CRP whereby it antagonizes endothelial NO synthase. Recognizing known associations between CRP and obesity and hypertension in humans, in the present study we tested the hypothesis that Fc?RIIB plays a role in obesity-induced hypertension in mice. Using radiotelemetry, we first demonstrated that the hypertension observed in transgenic mouse-CRP is mediated by the receptor, indicating that Fc?RIIB is capable of modifying blood pressure. We then discovered in a model of diet-induced obesity yielding equal adiposity in all study groups that whereas Fc?RIIB(+/+) mice developed obesity-induced hypertension, Fc?RIIB(-/-) mice were fully protected. Levels of CRP, the related pentraxin serum amyloid P component which is the CRP-equivalent in mice, and total IgG were unaltered by diet-induced obesity; Fc?RIIB expression in endothelium was also unchanged. However, whereas IgG isolated from chow-fed mice had no effect, IgG from high-fat diet-fed mice inhibited endothelial NO synthase in cultured endothelial cells, and this was an Fc?RIIB-dependent process. Thus, we have identified a novel role for Fc?RIIB in the pathogenesis of obesity-induced hypertension, independent of processes regulating adiposity, and it may entail an IgG-induced attenuation of endothelial NO synthase function. Approaches targeting Fc?RIIB may potentially offer new means to treat hypertension in obese individuals. PMID:25368023

Sundgren, Nathan C; Vongpatanasin, Wanpen; Boggan, Brigid-Meghan D; Tanigaki, Keiji; Yuhanna, Ivan S; Chambliss, Ken L; Mineo, Chieko; Shaul, Philip W

2015-02-01

280

Differential effects of TRPV1 receptor ligands against nicotine-induced depression-like behaviors  

PubMed Central

Background The contributions of brain cannabinoid (CB) receptors, typically CB1 (CB type 1) receptors, to the behavioral effects of nicotine (NC) have been reported to involve brain transient receptor potential vanilloid 1 (TRPV1) receptors, and the activation of candidate endogenous TRPV1 ligands is expected to be therapeutically effective. In the present study, the effects of TRPV1 ligands with or without affinity for CB1 receptors were examined on NC-induced depression-like behavioral alterations in a mouse model in order to elucidate the "antidepressant-like" contributions of TRPV1 receptors against the NC-induced "depression" observed in various types of tobacco abuse. Results Repeated subcutaneous NC treatments (NC group: 0.3 mg/kg, 4 days), like repeated immobilization stress (IM) (IM group: 10 min, 4 days), caused depression-like behavioral alterations in both the forced swimming (reduced swimming behaviors) and the tail suspension (increased immobility times) tests, at the 2 h time point after the last treatment. In both NC and IM groups, the TRPV1 agonists capsaicin (CP) and olvanil (OL) administered intraperitoneally provided significant antidepressant-like attenuation against these behavioral alterations, whereas the TRPV1 antagonist capsazepine (CZ) did not attenuate any depression-like behaviors. Furthermore, the endogenous TRPV1-agonistic CB1 agonists anandamide (AEA) and N-arachidonyldopamine (NADA) did not have any antidepressant-like effects. Nevertheless, a synthetic "hybrid" agonist of CB1 and TRPV1 receptors, arvanil (AR), caused significant antidepressant-like effects. The antidepressant-like effects of CP and OL were antagonized by the TRPV1 antagonist CZ. However, the antidepressant-like effects of AR were not antagonized by either CZ or the CB1 antagonist AM 251 (AM). Conclusions The antidepressant-like effects of TRPV1 agonists shown in the present study suggest a characteristic involvement of TRPV1 receptors in NC-induced depression-like behaviors, similar to those caused by IM. The strong antidepressant-like effects of the potent TRPV1 plus CB1 agonist AR, which has been reported to cause part of its TRPV1-mimetic and cannabimimetic effects presumably via non-TRPV1 or non-CB1 mechanisms support a contribution from other sites of action which may play a therapeutically important role in the treatment of NC abuse. PMID:21767384

2011-01-01

281

Expression of netrin-1 receptors in retina of oxygen-induced retinopathy in mice  

PubMed Central

Background Netrin-1 has been reported to promote retinal neovascularization in oxygen-induced retinopathy (OIR). However, netrin-1 receptors, which may mediate netrin-1 action during retinal neovascularization, have not been characterized. In this study, we investigated netrin-1 receptor subtype expression and associated changes in the retinas of mice with OIR. Methods C57BL/6J mice were exposed to 75±2% oxygen for 5 days and then returned to normal air to induce retinal neovascularization. Reverse transcriptase polymerase chain reaction (RT-PCR) and Western blot were used to examine the expression of netrin-1 receptor subtypes in the mouse retinas. Double staining of netrin-1 receptor subtypes and isolectin B4 was used to determine the location of the netrin-1 receptor subtypes in the retinas. Inhibition of retinal neovascularization was achieved by UNC5B shRNA plasmid intravitreal injection. Retinal neovascularization was examined by fluorescein angiography and quantification of preretinal neovascular nuclei in retinal sections. Results RT-PCR results showed that, except for UNC5A, netrin-1 receptor subtypes UNC5B, UNC5C, UNC5D, DCC, neogenin, and A2b were all expressed in the retinas of OIR mice 17 days after birth. Western blots showed that only UNC5B expression was significantly increased on that day, and immunofluorescence results showed that only UNC5B and neogenin were expressed in retinal vessels. Treatment of OIR mice with the UNC5B shRNA plasmid dramatically reduced neovascular tufts and neovascular outgrowth into the inner limiting membrane. Conclusions UNC5B may promote retinal neovascularization in OIR mice. PMID:25149138

2014-01-01

282

Myocardial beta-adrenergic receptor function during the development of pacing-induced heart failure.  

PubMed Central

The development of pacing-induced heart failure was studied in chronically instrumented, conscious dogs paced at a rate of 240 beats/min for 1 d (n = 6), 1 wk (n = 6), and 3-4 wk (n = 7). Left ventricular (LV) dP/dt was decreased (P < 0.0125) at 1 d, LV end-diastolic pressure and heart rate were increased (P < 0.0125) at 1 wk, but clinical signs of heart failure were only observed after 3-4 wk of pacing. Plasma norepinephrine rose (P < 0.0125) after 1 d of pacing, whereas LV norepinephrine was reduced (P < 0.0125) only after 3-4 wk of pacing. Both the fraction of beta-adrenergic receptors binding agonist with high affinity and adenylyl cyclase activity decreased (P < 0.0125) after 1 d of pacing. Total beta-adrenergic receptor density was not changed at any time point, but beta 1-adrenergic receptor density was decreased (P < 0.0125) after 1 wk. The functional activity of the guanine nucleotide binding protein, Gs, was not reduced, but the Gi alpha 2 isoform of the alpha subunit of the GTP-inhibitory protein rose after 3-4 wk of pacing. Thus, myocardial beta-adrenergic signal transduction undergoes change shortly (1d) after the initiation of pacing, before heart failure develops. The mechanism of beta-adrenergic receptor dysfunction in pacing-induced heart failure is characterized initially by elevated plasma levels of catecholamines, uncoupling of beta-adrenergic receptors, and a defect in the adenylyl cyclase catalytic unit. Selective down-regulation of beta 1-adrenergic receptors, increases in Gi alpha 2, and decreases in myocardial catecholamine levels occur as later events. Images PMID:8383704

Kiuchi, K; Shannon, R P; Komamura, K; Cohen, D J; Bianchi, C; Homcy, C J; Vatner, S F; Vatner, D E

1993-01-01

283

Delayed myocardial protection induced by endotoxin does not involve kinin B(1)-receptors.  

PubMed

Endotoxin is known to confer a delayed protection against myocardial infarction. Lipopolysaccharide (LPS) treatment also induces the de novo synthesis of kinin B(1)-receptors that are not present in normal conditions. The aim of this study was to evaluate whether LPS-induced B(1)-receptors are implicated in the reduction of infarct size brought about by LPS. Rabbits were submitted to a 30-min coronary artery occlusion and 3-h reperfusion sequence. Six groups were studied: pretreated or not (control animals) with LPS (5 microgram kg(-1) i.v.) 24 h earlier and treated 15 min before and throughout ischaemia - reperfusion with either the B(1)-antagonist R-715 (1 mg kg(-1) h(-1)), the B(1)-agonist Sar-[D-Phe(8)]-des-Arg(9)-bradykinin (15 microgram kg(-1) h(-1)) or vehicle (saline). Infarct size and area at risk were assessed by differential staining and planimetric analysis. The presence of B(1)-receptors in LPS-pretreated animals was confirmed by a decrease in mean arterial pressure in response to B(1) stimulation. LPS-pretreatment significantly reduced infarct size (6.4+/-1.7%, of area at risk vs 24.1+/-2.5% in control animals, P<0.05). This protection was not modified by B(1)-receptor antagonism (7.4+/-2.2%, NS) or stimulation (5.2+/-1.2%, NS). Neither antagonist nor agonist modified infarct size in control animals. In conclusion, these data suggest that LPS-induced myocardial protection in the rabbit is not related to concomitant de novo B(1)-receptor induction. PMID:11030723

Mazenot, C; Gobeil, F; Ribuot, C; Regoli, D; Godin-Ribuot, D

2000-10-01

284

Involvement of NMDA Receptors in Thiopental-Induced Loss of Righting Reflex, Antinociception and Anticonvulsion Effects in Mice  

Microsoft Academic Search

Potentiation of GABAA receptor-mediated inhibitory neurotransmission contributes to the anesthetic action of thiopental. However, the inhibiting action of general anesthetic on excitatory neurotransmission also purportedly underlies its effects. The aim of the study was to elucidate the role of glutamate receptors (NMDA and AMPA receptors) in thiopental-induced anesthesia. Intracerebroventricular (i.c.v.) NMDA (50 ng) significantly increased the induction time of loss

Zhi Jun Ge; Li Cai Zhang; Yin Ming Zeng; Ti Jun Da; Jun Ke Wang; Guo Xin Cui; Yong Fei Tan; Yan Ping Zhao; Guo Jun Liu

2007-01-01

285

Cannabinoid-Induced Mesenteric Vasodilation through an Endothelial Site Distinct from CB1 or CB2 Receptors  

Microsoft Academic Search

Cannabinoids, including the endogenous ligand arachidonyl ethanolamide (anandamide), elicit not only neurobehavioral but also cardiovascular effects. Two cannabinoid receptors, CB1 and CB2, have been cloned, and studies with the selective CB1 receptor antagonist SR141716A have implicated peripherally located CB1 receptors in the hypotensive action of cannabinoids. In rat mesenteric arteries, anandamide-induced vasodilation is inhibited by SR141716A, but other potent CB1

Zoltan Jarai; Jens A. Wagner; Karoly Varga; Kristy D. Lake; David R. Compton; Billy R. Martin; Anne M. Zimmer; Tom I. Bonner; Nancy E. Buckley; Eva Mezey; Raj K. Razdan; Andreas Zimmer; George Kunos

1999-01-01

286

Possible role of GABA-B receptor modulation in MPTP induced Parkinson's disease in rats.  

PubMed

Accumulating evidence strongly suggests that gamma amino butyric acid (GABA) receptors play a crucial role in the pathogenesis of Parkinson's disease (PD). Therefore, the present study was designed to investigate the role of GABA-B receptor modulation in experimental models of MPTP-induced PD. MPTP was administered repeatedly on 1st, 7th and 14th day intranigrally for the induction of PD in Male Wistar rats. Baclofen (10 and 20mg/kg) and GABA-B antagonist CGP35348 (10mg/kg) were given after induction of PD for 14 days. Different behavioural tasks were performed during 1st, 14th, 21st, 28th days after MPTP injection and biochemical parameters were estimated on day 28th. Central administration of MPTP showed significant impairment of motor behaviour and marked increase of oxidative damage LPO and GSH in striatum and cortex. Pro-inflammatory cytokines like TNF-? and IL-? were significantly increased in striatum region of MPTP treated rats. However, post treatment with baclofen significantly improved the motor abnormalities and attenuated the oxidative damage and neuro-inflammation in MPTP treated rats. CGP35348, GABA-B receptor antagonist, reversed the protective effect of baclofen GABA-B receptor play role in the neuroprotection. The present study concluded that baclofen produce beneficial effect against MPTP induced PD like symptoms rats through GABAergic mechanism. PMID:25547370

Tyagi, Ravi Kant; Bisht, Rohit; Pant, Jatin; Kumar, Puneet; Majeed, Abu Bakar Abdul; Prakash, Atish

2015-02-01

287

Involvement of peripheral NMDA receptor in melittin-induced thermographic flare.  

PubMed

Intradermal injection of an active compound of European honeybee toxin, melittin, into the forearm in humans produces temporary pain and evokes sustained increase of local skin temperature. This increase of skin temperature is suppressed by the pretreatment of a voltage gated sodium channel blocker, lidocaine, suggesting that neurogenic inflammation is involved in the skin temperature increase after the melittin treatment. In this study, we tested a hypothesis that the melittin-induced skin temperature increase is augmented by an N-methyl-D-aspartate (NMDA) glutamate receptor that is present on the peripheral terminals of cutaneous primary afferents. Skin temperature was examined after the local application of incremental doses of melittin by a computer-assisted-thermography in pentobarbital-anesthetized rats. Local subcutaneous glutamate was collected through a microdialysis probe and glutamate levels were measured by a high pressure liquid chromatography with electrochemical detection method. Intraplantar injection of melittin resulted in the increase of subcutaneous glutamate levels and the increase of local skin temperature, which was partially attenuated by co-injection of an NMDA receptor antagonist, MK-801. In addition, intraplantar injection of NMDA itself increased the local skin temperature. Our data suggest that melittin-induced increase of skin temperature is enhanced through the activation of peripheral NMDA receptors by locally released glutamate. We suggest that topical administration of NMDA receptor antagonists could be an effective treatment of neuro-inflammatory pain. PMID:22851351

Iwashita, Narihito; Nosaka, Shuichi; Koyama, Natsu

2012-10-01

288

Peroxisome proliferator-activated receptor ? confers resistance to peroxisome proliferator-activated receptor ?-induced apoptosis in colorectal cancer cells  

PubMed Central

Peroxisome proliferator-activated receptor ? (PPAR?) may serve as a useful target for drug development in non-diabetic diseases. However, some colorectal cancer cells are resistant to PPAR? agonists by mechanisms that are poorly understood. Here we provide the first evidence that elevated PPAR? expression and/or activation of PPAR? antagonize the ability of PPAR? to induce colorectal carcinoma cell death. More importantly, the opposing effects of PPAR? and PPAR? in regulating programmed cell death are mediated by survivin and caspase-3. We found that activation of PPAR? results in decreased survivin expression and increased caspase-3 activity, whereas activation of PPAR? counteracts these effects. Our findings suggest that PPAR? and PPAR? coordinately regulate cancer cell fate by controlling the balance between the cell death and survival and demonstrate that inhibition of PPAR? can reprogram PPAR? ligand-resistant cells to respond to PPAR? agonists. PMID:21765467

Wang, Dingzhi; Ning, Wei; Xie, Dianren; Guo, Lixia; DuBois, Raymond N.

2014-01-01

289

Alpha2-adrenergic receptor-induced vascular constriction in blacks and whites.  

PubMed

Black Americans have a reduced hypotensive response to the alpha2-adrenergic receptor agonist clonidine compared with whites, despite similar central sympathoinhibition. This reduced hypotensive response might be explained by greater postsynaptic vascular alpha2-adrenergic receptor vasoconstrictive response. However, clonidine has a low alpha2/alpha1 selectivity ratio. Therefore, to determine the role of altered alpha2-adrenergic receptor vascular sensitivity in ethnic differences in vascular response, we compared local vascular responses with the highly selective alpha2-adrenergic receptor agonist dexmedetomidine in healthy black (n=18) and white (n=19) subjects. Increasing doses of dexmedetomidine (0.001 to 1000 ng/min) were infused into a dorsal hand vein, and the local response was measured with a linear variable differential transformer. Dexmedetomidine caused pronounced venoconstriction, with an average (+/-SD) maximum response of 74.5+/-17.72% but with no difference between blacks and whites. There was substantial intersubject variability in the sensitivity to dexmedetomidine; the dose resulting in 50% (ED50) of maximum vasoconstriction ranged from 0.08 ng/min to 256 ng/min. The geometric mean ED50 was 2.28 ng/min (95% CI, 0.02 to 271.6 ng/min) in blacks and 1.58 ng/min (95% CI, 0.11 to 24.55 ng/min) in whites (P=0.59). Our data indicate that alpha2-adrenergic receptor-induced venoconstriction is similar in blacks and whites. These findings do not support the hypothesis that altered alpha2-adrenergic receptor sensitivity is the explanation for the decreased blood pressure response to systemic administration of clonidine in blacks. The response to dexmedetomidine provides a model that will allow further study of the regulation of alpha2-adrenergic receptor-mediated vascular responses PMID:14656950

Muszkat, Mordechai; Sofowora, Gbenga G; Wood, Alastair J J; Stein, C Michael

2004-01-01

290

IFN-alpha/beta-dependent cross-priming induced by specific toll-like receptor agonists.  

PubMed

Toll-like receptors (TLR) are pattern recognition receptors that have been identified as crucial in the initiation of innate immune responses against pathogens. They are thought to be involved in shaping appropriate adaptive immune responses, although their precise contribution has not yet been fully characterised. Our aim was to investigate in vivo the effect of different TLR stimuli on cellular immune responses. We examined the ability of a range of TLR stimuli to induce CD8+ T cell responses against a model soluble protein antigen, ovalbumin (OVA). We found that TLR 3, TLR 4, and TLR 9 agonists induced functional cross-priming, and that this process was dependent on IFN-alpha/beta signalling pathway. PMID:16823911

Durand, Vanessa; Wong, Simon Y C; Tough, David F; Le Bon, Agnes

2006-04-12

291

Ligand-Induced Dynamics of Neurotrophin Receptors Investigated by Single-Molecule Imaging Approaches  

PubMed Central

Neurotrophins are secreted proteins that regulate neuronal development and survival, as well as maintenance and plasticity of the adult nervous system. The biological activity of neurotrophins stems from their binding to two membrane receptor types, the tropomyosin receptor kinase and the p75 neurotrophin receptors (NRs). The intracellular signalling cascades thereby activated have been extensively investigated. Nevertheless, a comprehensive description of the ligand-induced nanoscale details of NRs dynamics and interactions spanning from the initial lateral movements triggered at the plasma membrane to the internalization and transport processes is still missing. Recent advances in high spatio-temporal resolution imaging techniques have yielded new insight on the dynamics of NRs upon ligand binding. Here we discuss requirements, potential and practical implementation of these novel approaches for the study of neurotrophin trafficking and signalling, in the framework of current knowledge available also for other ligand-receptor systems. We shall especially highlight the correlation between the receptor dynamics activated by different neurotrophins and the respective signalling outcome, as recently revealed by single-molecule tracking of NRs in living neuronal cells. PMID:25603178

Marchetti, Laura; Luin, Stefano; Bonsignore, Fulvio; de Nadai, Teresa; Beltram, Fabio; Cattaneo, Antonino

2015-01-01

292

Tamoxifen counteracts estradiol induced effects on striatal and hypophyseal dopamine receptors  

SciTech Connect

We investigated the ability of Tamoxifen (TAM), an antiestrogen drug, to counteract the modification induced by estrogens on dopamine (DA) receptors on striatum and on adenohypophysis of ovex female rats. Subacute treatment with 17..beta..-estradiol (E/sub 2/) at both low (0.1 ..mu..g/kg) and high (20 ..mu..g/kg) doses confirmed its ability to increase the number of striatal /sup 3/H-Spiperone (/sup 3/H-SPI) binding sites in a dose dependent manner. By contrast in the pituitary, only high doses of estrogen were effective in reducing the number of DA receptors. We treated ovex female rats for 15 days with TAM alone or associated with E/sub 2/, to see if these estrogenic effects could be suppressed by an antiestrogenic drug. TAM did not affect the number of striatal DA receptors, but significantly increased the adenohypophy-seal DA binding sites, without varying their affinity. No changes were observed in pituitary and striatal DA receptor density, even when TAM was injected in association with estradiol. In conclusions: TAM is able to counteract the effects estrogens have on DA receptors. However there is some evidence that it could influence the pituitary DA systems independently of it antiestrogenic activity.

Ferretti, C.; Blengio, M.; Ghi, P.; Racca, S.; Genazzani, E.; Portaleone, P.

1988-01-01

293

Post-receptor events associated with thrombin-induced platelet activation.  

PubMed

Thrombin is by far the most potent platelet agonist. Potentially this reflects multiple intracellular processes involved in transmitting the activation signal from the initial contact with a receptor, or binding site, to the final platelet response. Platelet membranes have two putative receptors: the high affinity glycoprotein Ib, whose function remains to be clarified, and the moderate affinity autoproteolytic receptor. The autoproteolytic receptor is a member of a family of receptors, with seven transmembrane domains, which interact with GTP-binding proteins. Distal to the membrane, several forms of phospholipase C are activated and roles for both heterotrimeric and low molecular mass GTP-binding proteins have been presented. Phospholipase C acts on inositol phospholipids to generate inositol trisphosphate and diacylglycerol, both of which function as second messengers in thrombin-induced platelet activation. Inositol trisphosphate mobilizes internal calcium stores and this is accompanied, and enhanced, by an influx of calcium from the external milieu. Diacylglycerol and calcium both serve to regulate the activity of multiple protein kinases which, in turn, mediate the phosphorylated state of numerous proteins. Phosphorylation can occur on serine, threonine or tyrosine residues of target proteins and the phosphorylated state of these proteins determines the final activation of the platelet. PMID:8148490

McNicol, A; Gerrard, J M

1993-12-01

294

? Opioid Receptor Antagonism and Prodynorphin Gene Disruption Block Stress-Induced Behavioral Responses  

PubMed Central

Previous studies have demonstrated that stress may increase prodynorphin gene expression, and ? opioid agonists suppress drug reward. Therefore, we tested the hypothesis that stress-induced release of endogenous dynorphin may mediate behavioral responses to stress and oppose the rewarding effects of cocaine. C57Bl/6 mice subjected to repeated forced swim testing (FST) using a modified Porsolt procedure at 30°C showed a characteristic stress-induced immobility response and a stress-induced analgesia observed with a tail withdrawal latency assay. Pretreatment with the ? opioid receptor antagonist nor-binaltorphimine (nor-BNI; 10 mg/kg, i.p.) blocked the stress-induced analgesia and significantly reduced the stress-induced immobility. The nor-BNI sensitivity of the behavioral responses suggests an activation of the ? opioid receptor by a stress-induced release of dynorphin peptides. Supporting this hypothesis, transgenic mice possessing a disrupted prodynorphin gene showed no increase in immobility or stress-induced analgesia after exposure to repeated FST. Because both stress and the ? opioid system can modulate the response to drugs of abuse, we tested the effects of forced swim stress on cocaine-conditioned place preference (CPP). FST-exposed mice conditioned with cocaine (15 mg/kg, s.c.) showed significant potentiation of place preference for the drug-paired chamber over the responses of unstressed mice. Surprisingly, nor-BNI pretreatment blocked stress-induced potentiation of cocaine CPP. Consistent with this result, mice lacking the prodynorphin gene did not show a stress-induced potentiation of cocaine CPP, whereas wild-type littermates did. The findings suggest that chronic swim stress may activate the ? opioid system to produce analgesia, immobility, and potentiation of the acute rewarding properties of cocaine in C57Bl/6 mice. PMID:12843270

McLaughlin, Jay P.; Marton-Popovici, Monica; Chavkin, Charles

2007-01-01

295

Thrombin-induced phosphoinositide hydrolysis in platelets. Receptor occupancy and desensitization.  

PubMed Central

The relationship between occupancy of thrombin receptors on platelets and enhanced phosphoinositide hydrolysis was analysed by examination of the dose-response relationship, the effects of thrombin inhibitors and the contribution of secondary effects. Washed human platelets were labelled with [3H]inositol, and agonist-induced accumulation of labelled inositol phosphates was measured. The dose-response curves and the time courses for alpha-thrombin- or gamma-thrombin-induced accumulation of inositol phosphates were similar to those for dense-granule secretion. Addition of the thrombin inhibitor hirudin to thrombin-activated platelets revealed that the continuous presence of active thrombin was required to maintain the accumulation of labelled inositol phosphates; the total production of inositol phosphates increased with longer periods of exposure to thrombin, reaching a maximum between 5 and 10 min. After activation with thrombin, the ability of a second, greater, addition of thrombin to induce additional phosphoinositide hydrolysis decreased with time; it was absent within 10 min after the first addition. The failure to sustain accumulation of labelled inositol phosphates or to respond to a second addition of thrombin beyond 10 min was not due to depletion of the pool of labelled precursors, because the platelets retained their ability to respond to collagen. Addition of ADP-consuming enzymes decreased sensitivity to thrombin, but inhibition of cyclo-oxygenase with indomethacin did not impair the thrombin-induced hydrolysis of phosphoinositides. It was concluded that thrombin-induced hydrolysis of phosphoinositides has characteristics consistent with mediation by a receptor that is similar to that that triggers dense-granule secretion, requires continuous presence of active thrombin to be maintained, is mediated by a receptor that displays thrombin-induced desensitization, and is only partially enhanced by secondary agents. PMID:3036080

Huang, E M; Detwiler, T C

1987-01-01

296

Dopamine D4 Receptor Counteracts Morphine-Induced Changes in ? Opioid Receptor Signaling in the Striosomes of the Rat Caudate Putamen  

PubMed Central

The mu opioid receptor (MOR) is critical in mediating morphine analgesia. However, prolonged exposure to morphine induces adaptive changes in this receptor leading to the development of tolerance and addiction. In the present work we have studied whether the continuous administration of morphine induces changes in MOR protein levels, its pharmacological profile, and MOR-mediated G-protein activation in the striosomal compartment of the rat CPu, by using immunohistochemistry and receptor and DAMGO-stimulated [35S]GTP?S autoradiography. MOR immunoreactivity, agonist binding density and its coupling to G proteins are up-regulated in the striosomes by continuous morphine treatment in the absence of changes in enkephalin and dynorphin mRNA levels. In addition, co-treatment of morphine with the dopamine D4 receptor (D4R) agonist PD168,077 fully counteracts these adaptive changes in MOR, in spite of the fact that continuous PD168,077 treatment increases the [3H]DAMGO Bmax values to the same degree as seen after continuous morphine treatment. Thus, in spite of the fact that both receptors can be coupled to Gi/0 protein, the present results give support for the existence of antagonistic functional D4R-MOR receptor-receptor interactions in the adaptive changes occurring in MOR of striosomes on continuous administration of morphine. PMID:24451133

Suárez-Boomgaard, Diana; Gago, Belén; Valderrama-Carvajal, Alejandra; Roales-Buján, Ruth; Van Craenenbroeck, Kathleen; Duchou, Jolien; Borroto-Escuela, Dasiel O.; Medina-Luque, José; de la Calle, Adelaida; Fuxe, Kjell; Rivera, Alicia

2014-01-01

297

BINDING OF POLYCHLORINATED BIPHENYLS CLASSIFIED AS EITHER PHENOBARBITONE-, 3-METHYLCHOLANTHRENE- OR MIXED-TYPE INDUCERS TO CYTOSOLIC AH RECEPTOR  

EPA Science Inventory

It has been postulated that reversible, high-affinity binding of 3-methyl-cholanthrene (MC)-type inducers to a receptor protein (the Ah receptor) in hepatic cytosol is essential for induction of aryl hydrocarbon hydroxylase (AHH) enzymic activity. To test this postulate, the bind...

298

Implication of mGlu5 receptor in the enhancement of morphine-induced hyperlocomotion under chronic treatment with zolpidem.  

PubMed

Long-term exposure to zolpidem induces drug dependence, and it is well known that the balance between the GABAergic and glutamatergic systems plays a critical role in maintaining the neuronal network. In the present study, we investigated the interaction between GABAA receptor ?1 subunit and mGlu5 receptor in the limbic forebrain including the N.Acc. after treatment with zolpidem for 7 days. mGlu5 receptor protein levels were significantly increased after treatment with zolpidem for 7 days, and this change was accompanied by the up-regulation of phospholipase C?1 and calcium/calmodulin-dependent protein kinase II?, which are downstream of mGlu5 receptor in the limbic forebrain. To confirm that mGlu5 receptor is directly involved in dopamine-related behavior in mice following chronic treatment with zolpidem, we measured morphine-induced hyperlocomotion after chronic treatment with zolpidem in the presence or absence of an mGlu5 receptor antagonist. Although chronic treatment with zolpidem significantly enhanced morphine-induced hyperlocomotion, this enhancement of morphine-induced hyperlocomotion was suppressed by treating it with the mGlu5 receptor antagonist MPEP. These results suggest that chronic treatment with zolpidem caused neural plasticity in response to activation of the mesolimbic dopaminergic system accompanied by an increase in mGlu5 receptor. PMID:24930812

Shibasaki, Masahiro; Ishii, Kazunori; Masukawa, Daiki; Ando, Koji; Ikekubo, Yuiko; Ishikawa, Yutori; Shibasaki, Yumiko; Mori, Tomohisa; Suzuki, Tsutomu

2014-09-01

299

Inducible and Reversible NR1 Knockout Reveals Crucial Role of the NMDA Receptor in Preserving Remote Memories in the Brain  

Microsoft Academic Search

Long-term storage of information is a hallmark feature of the brain, yet routine turnover of synaptic receptors appears to be intrinsically paradoxical to this capability. To investigate how the brain preserves its delicate synaptic efficacies, we generated inducible and reversible knockout mice in which the NMDA receptor can be temporarily switched off in the forebrain specifically during the storage stage.

Zhenzhong Cui; Huimin Wang; Yuansheng Tan; Kimberly A. Zaia; Shuqin Zhang; Joe Z. Tsien

2004-01-01

300

Agrin-induced acetylcholine receptor clustering in mammalian muscle requires tyrosine phosphorylation  

Microsoft Academic Search

Agrin is thought to be the nerve-derived fac- tor that initiates acetylcholine receptor (AChR) clus- tering at the developing neuromuscular junction. We have investigated the signaling pathway in mouse C2 myotubes and report that agrin induces a rapid but transient tyrosine phosphorylation of the AChR 13 sub- unit. As the 13-subunit tyrosine phosphorylation occurs before the formation of AChR clusters,

Michael Ferns; Michael Deiner; Zach Hall

1996-01-01

301

Inhibitory action of hydrogen sulfide on muscarinic receptor-induced contraction of isolated porcine irides  

Microsoft Academic Search

We investigated the pharmacological actions of hydrogen sulfide (H2S) using sodium hydrosulfide (NaHS) and sodium sulfide (Na2S) as donors on isolated porcine irides in the presence of tone induced by muscarinic receptor stimulation. Furthermore, we also investigated the mechanism of action of H2S in this smooth muscle. Isolated porcine iris muscle strips were set up in organ baths and prepared

Emmanuel M. Monjok; Kaustubh H. Kulkarni; Ghislaine Kouamou; Marshalyn McKoy; Catherine A. Opere; Odelia N. Bongmba; Ya Fatou Njie; Sunny E. Ohia

2008-01-01

302

Cordycepin-induced apoptosis and autophagy in breast cancer cells are independent of the estrogen receptor  

Microsoft Academic Search

Cordycepin (3-deoxyadenosine), found in Cordyceps spp., has been known to have many therapeutic effects including immunomodulatory, anti-inflammatory, antimicrobial, and anti-aging effects. Moreover, anti-tumor and anti-metastatic effects of cordycepin have been reported, but the mechanism causing cancer cell death is poorly characterized. The present study was designed to investigate whether the mechanisms of cordycepin-induced cell death were associated with estrogen receptor

Sunga Choi; Mi-Hee Lim; Ki Mo Kim; Byeong Hwa Jeon; Won O. Song; Tae Woong Kim

303

Ketamine-Induced NMDA Receptor Hypofunction as a Model of Memory Impairment and Psychosis  

Microsoft Academic Search

N-methyl-D-aspartate (NMDA) glutamate receptor antagonists are reported to induce schizophrenia-like symptoms in humans, including cognitive impairments. Shortcomings of most previous investigations include failure to maintain steady-state infusion conditions, test multiple doses and\\/or measure antagonist plasma concentrations. This double-blind, placebo-controlled, randomized, within-subjects comparison of three fixed subanesthetic, steady-state doses of intravenous ketamine in healthy males (n = 15) demonstrated dose-dependent increases

John W Newcomer; Nuri B Farber; Vesna Jevtovic-Todorovic; Gregg Selke; Angela Kelly Melson; Tamara Hershey; Suzanne Craft; John W Olney

1999-01-01

304

Retinoic acid receptors and muscle b-HLH proteins: partners in retinoid-induced myogenesis  

Microsoft Academic Search

The results reported here indicate that retinoic acid (RA) induces growth arrest and differentiation only in MyoD-expressing muscle cells. Transient transfection assays reveal a functional interaction between MyoD, a key myogenic regulator and RA-receptors, principal mediators of RA actions. Interestingly, we demonstrate that RXR-MyoD-containing complexes are recruited at specific MyoD DNA-binding sites in muscle cells. Furthermore, we also demonstrate that

Anne Froeschlé; Séverine Alric; Magali Kitzmann; Gilles Carnac; Frédéric Auradé; Cécile Rochette-Egly; Anne Bonnieu; A Bonnieu

1998-01-01

305

Molecular Mechanism of 17-Allylamino-17-demethoxygeldanamycin (17-AAG)-induced AXL Receptor Tyrosine Kinase Degradation*  

PubMed Central

The receptor tyrosine kinase AXL is overexpressed in many cancer types including thyroid carcinomas and has well established roles in tumor formation and progression. Proper folding, maturation, and activity of several oncogenic receptor tyrosine kinases require HSP90 chaperoning. HSP90 inhibition by the antibiotic geldanamycin or its derivative 17-allylamino-17-demethoxygeldanamycin (17-AAG) causes destabilization of its client proteins. Here we show that AXL is a novel client protein of HSP90. 17-AAG induced a time- and dose-dependent down-regulation of endogenous or ectopically expressed AXL protein, thereby inhibiting AXL-mediated signaling and biological activity. 17-AAG-induced AXL down-regulation specifically affected fully glycosylated mature receptor present on cell membrane. By using biotin and [35S]methionine labeling, we showed that 17-AAG caused depletion of membrane-localized AXL by mediating its degradation in the intracellular compartment, thus restricting its exposure on the cell surface. 17-AAG induced AXL polyubiquitination and subsequent proteasomal degradation; under basal conditions, AXL co-immunoprecipitated with HSP90. Upon 17-AAG treatment, AXL associated with the co-chaperone HSP70 and the ubiquitin E3 ligase carboxyl terminus of HSC70-interacting protein (CHIP). Overexpression of CHIP, but not of the inactive mutant CHIP K30A, induced accumulation of AXL polyubiquitinated species upon 17-AAG treatment. The sensitivity of AXL to 17-AAG required its intracellular domain because an AXL intracellular domain-deleted mutant was insensitive to the compound. Active AXL and kinase-dead AXL were similarly sensitive to 17-AAG, implying that 17-AAG sensitivity does not require receptor phosphorylation. Overall our data elucidate the molecular basis of AXL down-regulation by HSP90 inhibitors and suggest that HSP90 inhibition in anticancer therapy can exert its effect through inhibition of multiple kinases including AXL. PMID:23629654

Krishnamoorthy, Gnana Prakasam; Guida, Teresa; Alfano, Luigi; Avilla, Elvira; Santoro, Massimo; Carlomagno, Francesca; Melillo, Rosa Marina

2013-01-01

306

LTB4-induced transient neutropenia in the rat: a model for evaluating efficacy and bioavailability of LTB4 receptor antagonists.  

PubMed

An animal model of leukotriene B4- (LTB4) induced neutropenia has been developed to evaluate LTB4 receptor antagonists in vivo. LTB4, a potent chemotactic inflammatory mediator, when administered intravenously, induces a profound, rapid, and transient redistribution of blood neutrophils from the circulating pool to the marginated pool. This phenomenon is applied in the neutropenia model whereby circulating blood neutrophil counts prior to and after intravenous infusion of LTB4 are compared. Kinetics of LTB4-induced neutrophil responses are determined through the use of a Technicon H*1 automated blood cell analyzer. LTB4 receptor antagonists are identified by inhibition of LTB4-induced neutropenia. Standard antiinflammatory compounds including BW-755C, Abbott A-64077 (zileuton), dexamethasone-21-acetate, indomethacin, and naproxen did not affect LTB4-induced neutropenia. A potent LTB4 receptor antagonist, designated "RPR," inhibited LTB4-induced neutropenia following oral administration in a dose-dependent fashion. PMID:8305713

Pellas, T C; Colombo, C; Fryer, L R; Pastor, G; Haston, W; Raychaudhuri, A; Kotyuk, B; Greenspan, P D; Healy, C; DiPasquale, G

1993-11-01

307

Modest hypoxia significantly reduces triglyceride content and lipid droplet size in 3T3-L1 adipocytes  

SciTech Connect

Highlights: •Long-term hypoxia decreased the size of LDs and lipid storage in 3T3-L1 adipocytes. •Long-term hypoxia increased basal lipolysis in 3T3-L1 adipocytes. •Hypoxia decreased lipid-associated proteins in 3T3-L1 adipocytes. •Hypoxia decreased basal glucose uptake and lipogenic proteins in 3T3-L1 adipocytes. •Hypoxia-mediated lipogenesis may be an attractive therapeutic target against obesity. -- Abstract: Background: A previous study has demonstrated that endurance training under hypoxia results in a greater reduction in body fat mass compared to exercise under normoxia. However, the cellular and molecular mechanisms that underlie this hypoxia-mediated reduction in fat mass remain uncertain. Here, we examine the effects of modest hypoxia on adipocyte function. Methods: Differentiated 3T3-L1 adipocytes were incubated at 5% O{sub 2} for 1 week (long-term hypoxia, HL) or one day (short-term hypoxia, HS) and compared with a normoxia control (NC). Results: HL, but not HS, resulted in a significant reduction in lipid droplet size and triglyceride content (by 50%) compared to NC (p < 0.01). As estimated by glycerol release, isoproterenol-induced lipolysis was significantly lowered by hypoxia, whereas the release of free fatty acids under the basal condition was prominently enhanced with HL compared to NC or HS (p < 0.01). Lipolysis-associated proteins, such as perilipin 1 and hormone-sensitive lipase, were unchanged, whereas adipose triglyceride lipase and its activator protein CGI-58 were decreased with HL in comparison to NC. Interestingly, such lipogenic proteins as fatty acid synthase, lipin-1, and peroxisome proliferator-activated receptor gamma were decreased. Furthermore, the uptake of glucose, the major precursor of 3-glycerol phosphate for triglyceride synthesis, was significantly reduced in HL compared to NC or HS (p < 0.01). Conclusion: We conclude that hypoxia has a direct impact on reducing the triglyceride content and lipid droplet size via decreased glucose uptake and lipogenic protein expression and increased basal lipolysis. Such an hypoxia-induced decrease in lipogenesis may be an attractive therapeutic target against lipid-associated metabolic diseases.

Hashimoto, Takeshi, E-mail: thashimo@fc.ritsumei.ac.jp [Faculty of Sport and Health Science, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga 525-8577 (Japan)] [Faculty of Sport and Health Science, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga 525-8577 (Japan); Yokokawa, Takumi; Endo, Yuriko [Faculty of Sport and Health Science, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga 525-8577 (Japan)] [Faculty of Sport and Health Science, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga 525-8577 (Japan); Iwanaka, Nobumasa [Ritsumeikan Global Innovation Research Organization, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga 525-8577 (Japan)] [Ritsumeikan Global Innovation Research Organization, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga 525-8577 (Japan); Higashida, Kazuhiko [Faculty of Sport and Health Science, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga 525-8577 (Japan) [Faculty of Sport and Health Science, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga 525-8577 (Japan); Faculty of Sport Science, Waseda University, 2-579-15 Mikajima, Tokorozawa, Saitama 359-1192 (Japan); Taguchi, Sadayoshi [Faculty of Sport and Health Science, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga 525-8577 (Japan)] [Faculty of Sport and Health Science, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga 525-8577 (Japan)

2013-10-11

308

Triptolide sensitizes pancreatic cancer cells to TRAIL-induced activation of the death receptor pathway.  

PubMed

The tumor necrosis factor related apoptosis-inducing ligand (TRAIL) causes cancer cell death, but many cancers, including pancreatic cancer, are resistant to TRAIL therapy. A combination of TRAIL and the diterpene triepoxide, triptolide, is effective in inducing pancreatic cancer cell death. Triptolide increases levels of death receptor DR5 and decreases the pro-survival FLICE-like inhibitory protein (c-FLIP), which contribute to the activation of caspase-8. This combination further causes both lysosomal and mitochondrial membrane permeabilization, resulting in cell death. Our study provides a mechanism by which triptolide sensitizes TRAIL resistant cells, which may become a novel therapeutic strategy against pancreatic cancer. PMID:24662747

Chen, Zhiyu; Sangwan, Veena; Banerjee, Sulagna; Chugh, Rohit; Dudeja, Vikas; Vickers, Selwyn M; Saluja, Ashok K

2014-06-28

309

Hydrogen sulphide induces ? opioid receptor-dependent analgesia in a rodent model of visceral pain  

Microsoft Academic Search

Background  Hydrogen sulphide (H2S) is a gaseous neuro-mediator that exerts analgesic effects in rodent models of visceral pain by activating KATP channels. A body of evidence support the notion that KATP channels interact with endogenous opioids. Whether H2S-induced analgesia involves opioid receptors is unknown.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  The perception of painful sensation induced by colorectal distension (CRD) in conscious rats was measured by assessing

Eleonora Distrutti; Sabrina Cipriani; Barbara Renga; Andrea Mencarelli; Marco Migliorati; Stefano Cianetti; Stefano Fiorucci

2010-01-01

310

Chronic Administration of 5-HT1A Receptor Agonist Relieves Depression and Depression-Induced Hypoalgesia  

PubMed Central

Previous studies have shown that depressed patients as well as animal models of depression exhibit decreased sensitivity to evoked pain stimuli, and serotonin is indicated to be involved in depression-induced hypoalgesia. The purpose of this study was to investigate the potential role of 5-HT1A receptor in the depression-induced hypoalgesia. Acute or chronic administration of 5-HT1A receptor agonist, 8-OH-DPAT, was performed in olfactory bulbectomy (OB) and sham-operated rats. The depression-like behavior and pain thresholds were measured using open-field test and radiant heat thermal pain test, respectively. We found that acute administration of 8-OH-DPAT increased locomotor activity and pain thresholds in the sham rats but had no effect on the OB rats. In contrast, chronic administration of 8-OH-DPAT reduced locomotor activity and pain thresholds and restored them to normal level. Increased pain thresholds were also observed in the sham rats after the chronic administration. These results demonstrated that chronic administration of 8-OH-DPAT reversed the depression-induced decrease in pain sensitivity in rats, suggesting that 5-HT1A receptor may play a role in the depression-associated hypoalgesia. PMID:24592167

Qi, Wei-Jing

2014-01-01

311

Theaflavin-3, 3?-Digallate Induces Epidermal Growth Factor Receptor Down-Regulation  

PubMed Central

Black tea is one of the most popular beverages worldwide and especially in Western nations. Theaflavins, a mixture of theaflavin, theaflavin-3-gallate, theaflavin-3?-gallate and theaflavin-3, 3?-digallate (TF-3) are the major components of black tea. Among these black tea components, theaflavin is generally considered to be the more effective component for the inhibition of carcinogenesis. Recently, TF-3 has been shown to have an antiproliferative effect on tumor cells, but the mechanism is not clear. In this study, we showed that TF-3 induced internalization and down-regulation of the epidermal growth factor receptor (EGFR). These results suggested that TF-3 induces EGFR endocytosis and degradation. We further showed that TF-3 stimulated EGFR ubiquitination and tyrosine kinase activation. Interestingly, TF-3-induced EGFR down-regulation is inhibited by the proteasome inhibitor, MG132, but not by the EGFR specific receptor tyrosine kinase inhibitor, AG1478. Furthermore, pretreatment with TF-3 inhibited EGF-induced EGFR autophosphorylation, ERKs phosphorylation and AP-1 activation in JB6 Cl41 cells. In addition, TF-3 inhibited EGF-induced anchorage-independent cell transformation. Overall, our results indicate that TF-3 might exert chemopreventive effects through the down-regulation of the EGFR. PMID:16353237

Mizuno, Hideya; Cho, Yong-Yeon; Zhu, Feng; Ma, Wei-Ya; Bode, Ann M.; Yang, Chung S.; Ho, Chi-Tang; Dong, Zigang

2006-01-01

312

Norepinephrine signaling through ?-adrenergic receptors is critical for expression of cocaine-induced anxiety  

PubMed Central

Background Cocaine is a widely abused psychostimulant that has both rewarding and aversive properties. While the mechanisms underlying cocaine’s rewarding effects have been studied extensively, less attention has been paid to the unpleasant behavioral states induced by cocaine, such as anxiety. Methods In this study we evaluated the performance of dopamine ?-hydroxylase knockout (Dbh ?/?) mice, which lack norepinephrine (NE), in the elevated plus maze (EPM) to examine the contribution of noradrenergic signaling to cocaine-induced anxiety. Results We found that cocaine dose-dependently increased anxiety-like behavior in control (Dbh +/?) mice, as measured by a decrease in open arm exploration. Dbh ?/? mice had normal baseline performance in the EPM, but were completely resistant to the anxiogenic effects of cocaine. Cocaine-induced anxiety was also attenuated in Dbh +/? mice following administration of disulfiram, a DBH inhibitor. In experiments using specific adrenergic antagonists, we found that pretreatment with the ?-adrenergic receptor antagonist propranolol blocked cocaine-induced anxiety-like behavior in Dbh +/? and wild-type C57BL6/J mice, while the ?1 antagonist prazosin and the ?2 antagonist yohimbine had no effect. Conclusions These results indicate that noradrenergic signaling via ?-adrenergic receptors is required for cocaine-induced anxiety in mice. PMID:18083142

Schank, Jesse R.; Liles, L. Cameron; Weinshenker, David

2008-01-01

313

Bisdemethoxycurcumin Induces Apoptosis in Activated Hepatic Stellate Cells via Cannabinoid Receptor 2.  

PubMed

Activated Hepatic Stellate Cells (HSCs), major fibrogenic cells in the liver, undergo apoptosis when liver injuries cease, which may contribute to the resolution of fibrosis. Bisdemethoxycurcumin (BDMC) is a natural derivative of curcumin with anti-inflammatory and anti-cancer activities. The therapeutic potential of BDMC in hepatic fibrosis has not been studied thus far in the context of the apoptosis in activated HSCs. In the current study, we compared the activities of BDMC and curcumin in the HSC-T6 cell line and demonstrated that BDMC relatively induced a potent apoptosis. BDMC-induced apoptosis was mediated by a combinatory inhibition of cytoprotective proteins, such as Bcl2 and heme oxygenase-1 and increased generation of reactive oxygen species. Intriguingly, BDMC-induced apoptosis was reversed with co-treatment of sr144528, a cannabinoid receptor (CBR) 2 antagonist, which was confirmed with genetic downregulation of the receptor using siCBR2. Additionally, incubation with BDMC increased the formation of death-induced signaling complex in HSC-T6 cells. Treatment with BDMC significantly diminished total intracellular ATP levels and upregulated ATP inhibitory factor-1. Collectively, the results demonstrate that BDMC induces apoptosis in activated HSCs, but not in hepatocytes, by impairing cellular energetics and causing a downregulation of cytoprotective proteins, likely through a mechanism that involves CBR2. PMID:25594342

Lee, Phil Jun; Woo, Seung Je; Jee, Jun-Goo; Sung, Sang Hyun; Kim, Hong Pyo

2014-01-01

314

Involvement of chloride channel coupled GABA(C) receptors in the peripheral antinociceptive effect induced by GABA(C) receptor agonist cis-4-aminocrotonic acid.  

PubMed

We investigated the effect of chloride and potassium channel blockers on the antinociception induced by GABA(C) receptor agonist CACA (cis-4-aminocrotonic acid) using the paw pressure test, in which pain sensitivity was increased by an intraplantar injection (2 microg) of prostaglandin E(2) (PGE(2)). CACA administered locally into the right hindpaw (25, 50 and 100 microg/paw) elicited a dose-dependent antinociceptive effect which was demonstrated to be local, since only higher doses produced an effect when injected in the contralateral paw. The GABA(C) receptor antagonist (1,2,5,6 tetrahydropyridin-4-yl) methylphosphinic acid (TPMPA; 5, 10 and 20 microg/paw) antagonized, in a dose-dependent manner, the peripheral antinociception induced by CACA (100 microg), suggesting a specific effect. This effect was reversed by the chloride channel coupled receptor blocker picrotoxin (0.8 microg/paw). Glibenclamide (160 microg) and tolbutamide (320 microg), blockers of ATP-sensitive potassium channels, charybdotoxin (2 microg), a large-conductance potassium channel blocker, dequalinium (50 microg), a small-conductance potassium channel blocker, and cesium (500 microg), a non-specific potassium channel blocker did not modify the peripheral antinociception induced by CACA. This study provides evidence that activation of GABA(C) receptors in the periphery induces antinociception, that this effect results from the activation of chloride channel coupled GABA(C) receptors and that potassium channels appear not to be involved. PMID:17316706

Reis, Gláucia Maria Lopes; Duarte, Igor Dimitri Gama

2007-03-13

315

Dopamine induces light-adaptive retinomotor movements in bullfrog cones via D2 receptors and in retinal pigment epithelium via D1 receptors.  

PubMed

In the eyes of lower vertebrates, retinal photoreceptors and melanin pigment granules of the retinal pigment epithelium (RPE) exhibit characteristic retinomotor movements in response to changes in ambient illumination and to signals from an endogenous circadian clock. We previously reported that 3,4-dihydroxyphenylethylamine (dopamine) mimicked the effect of light on these movements in photo-receptors and RPE cells of green sunfish, Lepomis cyanellus, by interacting with D2 dopaminergic receptors. Here, we report that dopamine also mimics the effect of light on cone and RPE retinomotor movements in bullfrogs, Rana catesbeiana, i.e., dopamine induces cone contraction and RPE pigment dispersion. Dopamine induced cone contraction in isolated dark-adapted bullfrog retinas incubated in constant darkness in the presence of the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX). This effect of dopamine was inhibited by a D2 but not a D1 antagonist and mimicked by a D2 but not a D1 agonist. These results suggest that induction of cone contraction by dopamine is mediated by D2 dopaminergic receptors and that cone adenylate cyclase activity is inhibited. Thus, dopamine acts via the same type of receptor in both bullfrog and green sunfish retinas to induce cone contraction. In contrast, dopamine influences RPE retinomotor movement via different receptors in fish and bullfrog. Dopamine induced light-adaptive pigment dispersion in isolated dark-adapted bullfrog RPE-eyecups incubated in constant darkness in normal Ringer's solution. Because the retina was not present, these experiments demonstrate a direct effect of dopamine on bullfrog RPE. This effect of dopamine on bullfrog RPE was inhibited by a D1 but not a D2 antagonist and mimicked by a D1 but not a D2 agonist. Furthermore, agents that increase the concentration of intracellular cyclic AMP also induced pigment dispersion in dark-adapted bullfrog RPE-eyecups incubated in the dark. These results suggest that dopamine induces pigment dispersion in bullfrog RPE via D1 dopaminergic receptors. Thus, dopamine acts via different receptors on bullfrog (D1) versus green sunfish (D2) RPE to induce pigment dispersion. In addition, inhibitor studies indicate that pigment dispersion is actin dependent in teleost but not in bullfrog RPE. Dopamine-induced pigment dispersion was inhibited by cytochalasin D in isolated RPE sheets of green sunfish but not in RPE-eyecups of bullfrogs. Together, these observations indicate that dopamine mimics the effect of light on cone and RPE retinomotor movements in both fish and bullfrogs. However, in the RPE, different receptors mediate the effect of dopamine, and different cytoskeletal mechanisms are used to affect pigment transport.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:2156019

Dearry, A; Edelman, J L; Miller, S; Burnside, B

1990-04-01

316

Amphiregulin, an Epidermal Growth Factor Receptor Ligand, Plays an Essential Role in the Pathogenesis of Transforming Growth Factor-?-induced Pulmonary Fibrosis  

PubMed Central

Dysregulated amphiregulin (AR) expression and EGR receptor (EGFR) activation have been described in animal models of pulmonary fibrosis and in patients with idiopathic pulmonary fibrosis. However, the exact role of AR in the pathogenesis of pulmonary fibrosis has not been clearly defined. Here, we show that a potent profibrogenic cytokine TGF-?1 significantly induced the expression of AR in lung fibroblasts in vitro and in murine lungs in vivo. AR stimulated NIH3T3 fibroblast cell proliferation in a dose-dependent manner. Silencing of AR expression by siRNA or chemical inhibition of EGFR signaling, utilizing AG1478 and gefitinib, significantly reduced the ability of TGF-?1 to stimulate fibroblast proliferation and expression of ?-smooth muscle actin, collagen, and other extracellular matrix-associated genes. TGF-?1-stimulated activation of Akt, ERK, and Smad signaling was also significantly inhibited by these interventions. Consistent with these in vitro findings, AR expression was impressively increased in the lungs of TGF-?1 transgenic mice, and either siRNA silencing of AR or chemical inhibition of EGFR signaling significantly reduced TGF-?1-stimulated collagen accumulation in the lung. These studies showed a novel regulatory role for AR in the pathogenesis of TGF-?1-induced pulmonary fibrosis. In addition, these studies suggest that AR, or AR-activated EGFR signaling, is a potential therapeutic target for idiopathic pulmonary fibrosis associated with TGF-?1 activation. PMID:23086930

Zhou, Yang; Lee, Jae-Young; Lee, Chang-Min; Cho, Won-Kyung; Kang, Min-Jong; Koff, Jonathan L.; Yoon, Pyeong-Oh; Chae, Jeiwook; Park, Han-Oh; Elias, Jack A.; Lee, Chun Geun

2012-01-01

317

Liver growth factor (LGF) induces testicular regeneration in EDS-treated rats and increases protein levels of class B scavenger receptors.  

PubMed

The aim of the present work was to determine the effects of liver growth factor (LGF) on the regeneration process of rat testes after chemical castration induced by ethane dimethanesulfonate (EDS), by analyzing some of the most relevant proteins involved in cholesterol metabolism, such as hormone sensitive lipase (HSL), 3-?-hydroxysteroid dehydrogenase (3BHSD), scavenger receptor SR-BI and other components of the SR family that could contribute to the recovery of steroidogenesis and spermatogenesis in the testis. Sixty male rats were randomized to non-treated (controls), LGF-treated, EDS-treated, and EDS+LGF-treated groups. Testes were obtained at days 10 (T1), 21 (T2), and 35 (T3) after EDS treatment, embedded in paraffin, and analyzed by immunohistochemistry and Western blot. LGF improved the recovery of the seminiferous epithelia, the appearance of the mature pattern of Leydig cell interstitial distribution and the expression of mature SR-BI. Moreover, LGF treatment resulted in partial recovery of HSL expression in Leydig cells and spermatogonia. No changes in serum testosterone were observed in control and LGF-treated rats, but in EDS-castrated animals LGF treatment induced a progressive increase of serum testosterone levels and 3BHSD expression. Based on the pivotal role of SR-BI in the uptake of cholesteryl esters from HDL, it is suggested that the observed effects of LGF would facilitate the provision of cholesterol for sperm cell growth and Leydig cell recovery. PMID:25389365

Lobo, Mvt; Arenas, Mi; Huerta, L; Sacristán, S; Pérez-Crespo, M; Gutiérrez-Adán, A; Diaz-Gil, Jj; Lasunción, Ma; Martín-Hidalgo, A

2014-11-11

318

Association between GABAA Receptor Subunit Gene Cluster and Zolpidem-Induced Complex Sleep Behaviors in Han Chinese  

PubMed Central

Study Objectives: To investigate and elucidate the role of GABAA receptor subunits, specifically the 2 genetic markers at the GABAA ?1 and GABAA ?6 receptors, in zolpidem-induced complex sleep behaviors (CSBs). Design: Genetic association study. Setting: Kaohsiung Medical University-affiliated hospitals, Kaohsiung, Taiwan. Patients: 30 zolpidem-induced CSB subjects and 37 controls. Interventions: N/A. Measurements and Results: The ?2 test demonstrated an association between the A15G variant at the GABAA ?1 receptor subunit gene and zolpidem-induced CSBs (P = 0.007). The adjusted odds ratio of the GABAA ?1 receptor subunit genotype for the risk of zolpidem-induced CSBs was approximately 10 (OR = 9.99, 95% CI = 1.82, 74.87; P = 0.013). Conclusions: The finding reveals that the A15G variant at the GABAA ?1 receptor subunit gene confers a high risk of zolpidem-induced CSBs and may be considered in clinical services. Citation: Tsai JH; Yang P; Lin HH; Cheng Kh; Yang YH; Wu MT; Chen CC. Association between GABAA receptor subunit gene cluster and zolpidem-induced complex sleep behaviors in Han Chinese. SLEEP 2013;36(2):197–202. PMID:23372267

Tsai, Jui-Hsiu; Yang, Pinchen; Lin, Hung-Hsun; Cheng, Kuang-hung; Yang, Yi-Hsin; Wu, Ming-Tsang; Chen, Cheng-Chung

2013-01-01

319

Dopamine D2 receptor-mediated Akt/PKB signalling: initiation by the D2S receptor and role in quinpirole-induced behavioural activation  

PubMed Central

The short and long isoforms of the dopamine D2 receptor (D2S and D2L respectively) are highly expressed in the striatum. Functional D2 receptors activate an intracellular signalling pathway that includes a cAMP-independent route involving Akt/GSK3 (glycogen synthase kinase 3). To investigate the Akt/GSK3 response to the seldom-studied D2S receptor, we established a rat D2S receptor-expressing cell line [HEK (human embryonic kidney)-293/rD2S]. We found that in HEK-293/rD2S cells, the D2/D3 agonists bromocriptine and quinpirole significantly induced Akt and GSK3 phosphorylation, as well as ERK1/2 (extracellular-signal-regulated kinase 1/2) activation. The D2S receptor-induced Akt signals were profoundly inhibited by the internalization blockers monodansyl cadaverine and concanavalin A. Activation of the D2S receptor in HEK-293/rD2S cells appeared to trigger Akt/phospho-Akt translocation to the cell membrane. In addition to our cell culture experiments, we studied D2 receptor-dependent Akt in vivo by systemic administration of the D2/D3 agonist quinpirole. The results show that quinpirole evoked Akt-Ser473 phosphorylation in the ventral striatum. Furthermore, intra-accumbens administration of wortmannin, a PI3K (phosphoinositide 3-kinase) inhibitor, significantly suppressed the quinpirole-evoked behavioural activation. Overall, we demonstrate that activation of the dopamine D2S receptor stimulates Akt/GSK3 signalling. In addition, in vivo Akt activity in the ventral striatum appears to play an important role in systemic D2/D3 agonist-induced behavioural activation. PMID:22909302

Chen, Han-Ting; Ruan, Nan-Yu; Chen, Jin-Chung; Lin, Tzu-Yung

2012-01-01

320

Amygdala opioid receptors mediate the electroacupuncture-induced deterioration of sleep disruptions in epilepsy rats  

PubMed Central

Background Clinical and experimental evidence demonstrates that sleep and epilepsy reciprocally affect each other. Previous studies indicated that epilepsy alters sleep homeostasis; in contrast, sleep disturbance deteriorates epilepsy. If a therapy possesses both epilepsy suppression and sleep improvement, it would be the priority choice for seizure control. Effects of acupuncture of Feng-Chi (GB20) acupoints on epilepsy suppression and insomnia treatment have been documented in the ancient Chinese literature, Lingshu Jing (Classic of the Miraculous Pivot). Therefore, this study was designed to investigate the effect of electroacupuncture (EA) stimulation of bilateral Feng-Chi acupoints on sleep disruptions in rats with focal epilepsy. Results Our result indicates that administration of pilocarpine into the left central nucleus of amygdala (CeA) induced focal epilepsy and decreased both rapid eye movement (REM) sleep and non-REM (NREM) sleep. High-frequency (100 Hz) EA stimulation of bilateral Feng-Chi acupoints, in which a 30-min EA stimulation was performed before the dark period of the light:dark cycle in three consecutive days, further deteriorated pilocarpine-induced sleep disruptions. The EA-induced exacerbation of sleep disruption was blocked by microinjection of naloxone, ?- (naloxonazine), ?- (nor-binaltorphimine) or ?-receptor antagonists (natrindole) into the CeA, suggesting the involvement of amygdaloid opioid receptors. Conclusion The present study suggests that high-frequency (100 Hz) EA stimulation of bilateral Feng-Chi acupoints exhibits no benefit in improving pilocarpine-induced sleep disruptions; in contrast, EA further deteriorated sleep disturbances. Opioid receptors in the CeA mediated EA-induced exacerbation of sleep disruptions in epileptic rats. PMID:24215575

2013-01-01

321

Stress-induced sensitization of cortical adrenergic receptors following a history of cannabinoid exposure  

PubMed Central

The cannabinoid receptor agonist, WIN 55,212-2, increases extracellular norepinephrine levels in the rat frontal cortex under basal conditions, likely via desensitization of inhibitory ?2-adrenergic receptors located on norepinephrine terminals. Here, the effect of WIN 55,212-2 on stress-induced norepinephrine release was assessed in the medial prefrontal cortex (mPFC), in adult male Sprague-Dawley rats using in vivo microdialysis. Systemic administration of WIN 55,212-2 thirty minutes prior to stressor exposure prevented stress-induced cortical norepinephrine release induced by a single exposure to swim when compared to vehicle. To further probe cortical cannabinoid-adrenergic interactions, postsynaptic ?2-adrenergic receptor (AR)-mediated responses were assessed in mPFC pyramidal neurons using electrophysiological analysis in an in vitro cortical slice preparation. We confirm prior studies showing that clonidine increases cortical pyramidal cell excitability and that this was unaffected by exposure to acute stress. WIN 55,212-2, via bath application, blocked postsynaptic ?2-AR mediated responses in cortical neurons irrespective of exposure to stress. Interestingly, stress exposure prevented the desensitization of ?2-AR mediated responses produced by a history of cannabinoid exposure. Together, these data indicate the stress-dependent nature of cannabinoid interactions via both pre- and postsynaptic ARs. In summary, microdialysis data indicate that cannabinoids restrain stress-induced cortical NE efflux. Electrophysiology data indicate that cannabinoids also restrain cortical cell excitability under basal conditions; however, stress interferes with these CB1-?2 AR interactions, potentially contributing to over-activation of pyramidal neurons in mPFC. Overall, cannabinoids are protective of the NE system and cortical excitability but stress can derail this protective effect, potentially contributing to stress-related psychopathology. These data add to the growing evidence of complex, stress-dependent modulation of monoaminergic systems by cannabinoids and support the potential use of cannabinoids in the treatment of stress-induced noradrenergic dysfunction. PMID:22677142

Reyes, B.A.S.; Szot, P.; Sikkema, C.; Cathel, A. M.; Kirby, L.G.; Van Bockstaele, E.J.

2014-01-01

322

Adenosine A2A receptor induces protein kinase A-dependent functional modulation of human (alpha)3(beta)4 nicotinic receptor.  

PubMed

Adenosine modulates the function of nicotinic ACh receptors (nAChRs) in a variety of preparations, possibly through pathways involving protein kinase A (PKA), but these phenomena have not yet been investigated in detail. In this work we studied, using the patch clamp technique, the functional modulation of recombinant human ?3?4 nAChR by the A2A adenosine receptor, co-expressed in HEK cells. Tonic activation of A2A receptor slowed current decay during prolonged applications of nicotine and accelerated receptor recovery from desensitization. Together, these changes resulted into a more sustained current response upon multiple nicotine or ACh applications. These findings were confirmed in cultured mouse superior cervical ganglion neurones, which express nAChR containing the ?3 subunit together with ?2 and/or ?4 and A2A receptor. Expression of the A2A receptor in HEK cells also increased the apparent potency of nAChR for nicotine, further supporting a general A2A-induced gain of function for nAChR. These effects were dependent on PKA since the direct activation of PKA mimicked, and its inhibition prevented almost completely, the effects of the A2A receptor. Mutations of R385 and S388 in the cytoplasmic loop of the ?3 subunit abolished the functional modulation of nAChR induced by activation of A2A receptor, PKA and other Ser/Thr kinases, suggesting that this region constitutes a putative consensus site for these kinases. These data provide conclusive evidence that activation of the A2A receptor determines functional changes PMID:21486776

Di Angelantonio, Silvia; Piccioni, Alessio; Moriconi, Claudia; Trettel, Flavia; Cristalli, Gloria; Grassi, Francesca; Limatola, Cristina

2011-06-01

323

Mu-opioid receptor activation induces transcriptional plasticity in the central extended amygdala.  

PubMed

Addiction develops from the gradual adaptation of the brain to chronic drug exposure, and involves genetic reprogramming of neuronal function. The central extended amygdala (EAc) is a network formed by the central amygdala and the bed nucleus of the stria terminalis. This key site controls drug craving and seeking behaviors, and has not been investigated at the gene regulation level. We used Affymetrix microarrays to analyze transcriptional activity in the murine EAc, with a focus on mu-opioid receptor-associated events because these receptors mediate drug reward and dependence. We identified 132 genes whose expression is regulated by a chronic escalating morphine regimen in the EAc from wild-type but not mu-opioid receptor knockout mice. These modifications are mostly EAc-specific. Gene ontology analysis reveals an overrepresentation of neurogenesis, cell growth and signaling protein categories. A separate quantitative PCR analysis of genes in the last of these groups confirms the dysregulation of both orphan (Gpr88) and known (DrD1A, Adora2A, Cnr1, Grm5, Gpr6) G protein-coupled receptors, scaffolding (PSD95, Homer1) and signaling (Sgk, Cap1) proteins, and neuropeptides (CCK, galanin). These transcriptional modifications do not occur following a single morphine injection, and hence result from long-term adaptation to excessive mu receptor activation. Proteins encoded by these genes are classically associated with spine modules function in other brain areas, and therefore our data suggest a remodeling of EAc circuits at sites where glutamatergic and monoaminergic afferences interact. Together, mu receptor-dependent genes identified in this study potentially contribute to drug-induced neural plasticity, and provide a unique molecular repertoire towards understanding drug craving and relapse. PMID:18588537

Befort, K; Filliol, D; Ghate, A; Darcq, E; Matifas, A; Muller, J; Lardenois, A; Thibault, C; Dembele, D; Le Merrer, J; Becker, J A J; Poch, O; Kieffer, B L

2008-06-01

324

Activation of Spinal ?- and ?-Opioid Receptors Potently Inhibits Substance P Release Induced by Peripheral Noxious Stimuli  

PubMed Central

Over the past few years, ?-opioid receptors (DOPRs) and ?-opioid receptors (MOPRs) have been shown to interact with each other. We have previously seen that expression of MOPR is essential for morphine and inflammation to potentiate the analgesic properties of selective DOPR agonists. In vivo, it is not clear whether MOPRs and DOPRs are expressed in the same neurons. Indeed, it was recently proposed that these receptors are segregated in different populations of nociceptors, with MOPRs and DOPRs expressed by peptidergic and nonpeptidergic fibers, respectively. In the present study, the role and the effects of DOPR- and MOPR-selective agonists in two different pain models were compared. Using preprotachykinin A knock-out mice, we first confirmed that substance P partly mediates intraplantar formalin- and capsaicin-induced pain behaviors. These mice had a significant reduction in pain behavior compared with wild-type mice. We then measured the effects of intrathecal deltorphin II (DOPR agonist) and DAMGO (MOPR agonist) on pain-like behavior, neuronal activation, and substance P release following formalin and capsaicin injection. We found that both agonists were able to decrease formalin- and capsaicin-induced pain, an effect that was correlated with a reduction in the number of c-fos-positive neurons in the superficial laminae of the lumbar spinal cord. Finally, visualization of NK1 (neurokinin 1) receptor internalization revealed that DOPR and MOPR activation strongly reduced formalin- and capsaicin-induced substance P release via direct action on primary afferent fibers. Together, our results indicate that functional MOPRs and DOPRs are both expressed by peptidergic nociceptors. PMID:21917790

Beaudry, Hélène; Dubois, Dave; Gendron, Louis

2013-01-01

325

A dopamine receptor contributes to paraquat-induced neurotoxicity in Drosophila.  

PubMed

Long-term exposure to environmental oxidative stressors, like the herbicide paraquat (PQ), has been linked to the development of Parkinson's disease (PD), the most frequent neurodegenerative movement disorder. Paraquat is thus frequently used in the fruit fly Drosophila melanogaster and other animal models to study PD and the degeneration of dopaminergic neurons (DNs) that characterizes this disease. Here, we show that a D1-like dopamine (DA) receptor, DAMB, actively contributes to the fast central nervous system (CNS) failure induced by PQ in the fly. First, we found that a long-term increase in neuronal DA synthesis reduced DAMB expression and protected against PQ neurotoxicity. Secondly, a striking age-related decrease in PQ resistance in young adult flies correlated with an augmentation of DAMB expression. This aging-associated increase in oxidative stress vulnerability was not observed in a DAMB-deficient mutant. Thirdly, targeted inactivation of this receptor in glutamatergic neurons (GNs) markedly enhanced the survival of Drosophila exposed to either PQ or neurotoxic levels of DA, whereas, conversely, DAMB overexpression in these cells made the flies more vulnerable to both compounds. Fourthly, a mutation in the Drosophila ryanodine receptor (RyR), which inhibits activity-induced increase in cytosolic Ca(2+), also strongly enhanced PQ resistance. Finally, we found that DAMB overexpression in specific neuronal populations arrested development of the fly and that in vivo stimulation of either DNs or GNs increased PQ susceptibility. This suggests a model for DA receptor-mediated potentiation of PQ-induced neurotoxicity. Further studies of DAMB signaling in Drosophila could have implications for better understanding DA-related neurodegenerative disorders in humans. PMID:25158689

Cassar, Marlène; Issa, Abdul-Raouf; Riemensperger, Thomas; Petitgas, Céline; Rival, Thomas; Coulom, Hélène; Iché-Torres, Magali; Han, Kyung-An; Birman, Serge

2015-01-01

326

Progesterone-induced activation of membrane-bound progesterone receptors in murine macrophage cells.  

PubMed

Parturition is an inflammatory process mediated to a significant extent by macrophages. Progesterone (P4) maintains uterine quiescence in pregnancy, and a proposed functional withdrawal of P4 classically regulated by nuclear progesterone receptors (nPRs) leads to labor. P4 can affect the functions of macrophages despite the reported lack of expression of nPRs in these immune cells. Therefore, in this study we investigated the effects of the activation of the putative membrane-associated PR on the function of macrophages (a key cell for parturition) and discuss the implications of these findings for pregnancy and parturition. In murine macrophage cells (RAW 264.7), activation of mPRs by P4 modified to be active only extracellularly by conjugation to BSA (P4BSA, 1.0×10(-7)?mol/l) caused a pro-inflammatory shift in the mRNA expression profile, with significant upregulation of the expression of cyclooxygenase 2 (COX2 (Ptgs2)), Il1B, and Tnf and downregulation of membrane progesterone receptor alpha (Paqr7) and oxytocin receptor (Oxtr). Pretreatment with PD98059, a MEK1/2 inhibitor, significantly reduced P4BSA-induced expression of mRNA of Il1B, Tnf, and Ptgs2. Inhibition of protein kinase A (PKA) by H89 blocked P4BSA-induced expression of Il1B and Tnf mRNA. P4BSA induced rapid phosphorylation of MEK1/2 and CREB (a downstream target of PKA). This phosphorylation was inhibited by pretreatment with PD98059 and H89, respectively, revealing that MEK1/2 and PKA are two of the components involved in mPR signaling. Taken together, these results indicate that changes in membrane progesterone receptor alpha expression and signaling in macrophages are associated with the inflammatory responses; and that these changes might contribute to the functional withdrawal of P4 related to labor. PMID:25472814

Lu, Jing; Reese, Joshua; Zhou, Ying; Hirsch, Emmet

2015-02-01

327

Activation of PPAR gamma receptors reduces levodopa-induced dyskinesias in 6-OHDA-lesioned rats.  

PubMed

Long-term administration of l-3,4-dihydroxyphenylalanine (levodopa), the mainstay treatment for Parkinson's disease (PD), is accompanied by fluctuations in its duration of action and motor complications (dyskinesia) that dramatically affect the quality of life of patients. Levodopa-induced dyskinesias (LID) can be modeled in rats with unilateral 6-OHDA lesions via chronic administration of levodopa, which causes increasingly severe axial, limb, and orofacial abnormal involuntary movements (AIMs) over time. In previous studies, we showed that the direct activation of CB1 cannabinoid receptors alleviated rat AIMs. Interestingly, elevation of the endocannabinoid anandamide by URB597 (URB), an inhibitor of endocannabinoid catabolism, produced an anti-dyskinetic response that was only partially mediated via CB1 receptors and required the concomitant blockade of transient receptor potential vanilloid type-1 (TRPV1) channels by capsazepine (CPZ) (Morgese et al., 2007). In this study, we showed that the stimulation of peroxisome proliferator-activated receptors (PPAR), a family of transcription factors activated by anandamide, contributes to the anti-dyskinetic effects of URB+CPZ, and that the direct activation of the PPAR? subtype by rosiglitazone (RGZ) alleviates levodopa-induced AIMs in 6-OHDA rats. AIM reduction was associated with an attenuation of levodopa-induced increase of dynorphin, zif-268, and of ERK phosphorylation in the denervated striatum. RGZ treatment did not decrease striatal levodopa and dopamine bioavailability, nor did it affect levodopa anti-parkinsonian activity. Collectively, these data indicate that PPAR? may represent a new pharmacological target for the treatment of LID. PMID:25486547

Martinez, A A; Morgese, M G; Pisanu, A; Macheda, T; Paquette, M A; Seillier, A; Cassano, T; Carta, A R; Giuffrida, A

2015-02-01

328

Substance P reduces TNF-?-induced apoptosis in human tenocytes through NK-1 receptor stimulation  

PubMed Central

Background It has been hypothesised that an upregulation of the neuropeptide substance P (SP) and its preferred receptor, the neurokinin-1 receptor (NK-1 R), is a causative factor in inducing tenocyte hypercellularity, a characteristic of tendinosis, through both proliferative and antiapoptotic stimuli. We have demonstrated earlier that SP stimulates proliferation of human tenocytes in culture. Aim The aim of this study was to investigate whether SP can mediate an antiapoptotic effect in tumour necrosis factor-? (TNF-?)-induced apoptosis of human tenocytes in vitro. Results A majority (approximately 75%) of tenocytes in culture were immunopositive for TNF Receptor-1 and TNF Receptor-2. Exposure of the cells to TNF-? significantly decreased cell viability, as shown with crystal violet staining. TNF-? furthermore significantly increased the amount of caspase-10 and caspase-3 mRNA, as well as both BID and cleaved-poly ADP ribosome polymerase (c-PARP) protein. Incubation of SP together with TNF-? resulted in a decreased amount of BID and c-PARP, and in a reduced lactate dehydrogenase release, as compared to incubation with TNF-? alone. The SP effect was blocked with a NK-1 R inhibitor. Discussion This study shows that SP, through stimulation of the NK-1 R, has the ability to reduce TNF-?-induced apoptosis of human tenocytes. Considering that SP has previously been shown to stimulate tenocyte proliferation, the study confirms SP as a potent regulator of cell-turnover in tendon tissue, capable of stimulating hypercellularity through different mechanisms. This gives further support for the theory that the upregulated amount of SP seen in tendinosis could contribute to hypercellularity. PMID:23996004

Backman, Ludvig J; Eriksson, Daniella E; Danielson, Patrik

2014-01-01

329

Inhibition of N-methyl-D-aspartate receptors increases paraoxon-induced apoptosis in cultured neurons  

SciTech Connect

Organophosphorus (OP) compounds, used as insecticides and chemical warfare agents, are potent neurotoxins. We examined the neurotoxic effect of paraoxon (O,O-diethyl O-p-nitrophenyl phosphate), an organophosphate compound, and the role of NMDA receptors as a mechanism of action in cultured cerebellar granule cells. Paraoxon is neurotoxic to cultured rat cerebellar granule cells in a time- and concentration-dependent manner. Cerebellar granule cells are less sensitive to the neurotoxic effects of paraoxon on day in vitro (DIV) 4 than neurons treated on DIV 8. Surprisingly, the N-methyl-D-aspartate (NMDA) receptor antagonist, MK-801, enhances paraoxon-mediated neurotoxicity suggesting that NMDA receptors may play a protective role. Pretreatment with a subtoxic concentration of N-methyl-D-aspartate (NMDA) [100 {mu}M] protects about 40% of the vulnerable neurons that would otherwise die from paraoxon-induced neurotoxicity. Moreover, addition of a neuroprotective concentration of NMDA 3 h after treatment with paraoxon provides the same level of protection. Because paraoxon-mediated neuronal cell death is time-dependent, we hypothesized that apoptosis may be involved. Paraoxon increases apoptosis about 10-fold compared to basal levels. The broad-spectrum caspase inhibitor (Boc-D-FMK) and the caspase-9-specific inhibitor (Z-LEHD-FMK) protect against paraoxon-mediated apoptosis, paraoxon-stimulated caspase-3 activity and neuronal cell death. MK-801 increases, whereas NMDA blocks paraoxon-induced apoptosis and paraoxon-stimulated caspase-3 activity. These results suggest that activation of NMDA receptors protect neurons against paraoxon-induced neurotoxicity by blocking apoptosis initiated by paraoxon.

Wu Xuan [Department of Neurology, Uniformed Services University of the Health Sciences, Building A, Room 1036, 4301 Jones Bridge Road, Bethesda, MD 20814 (United States); Tian Feng [Department of Neurology, Uniformed Services University of the Health Sciences, Building A, Room 1036, 4301 Jones Bridge Road, Bethesda, MD 20814 (United States); Okagaki, Peter [Department of Neurology, Uniformed Services University of the Health Sciences, Building A, Room 1036, 4301 Jones Bridge Road, Bethesda, MD 20814 (United States); Marini, Ann M. [Department of Neurology, Uniformed Services University of the Health Sciences, Building A, Room 1036, 4301 Jones Bridge Road, Bethesda, MD 20814 (United States)]. E-mail: amarini@usuhs.mil

2005-10-01

330

alpha-Adrenoceptor and opioid receptor modulation of clonidine-induced antinociception.  

PubMed Central

1. The antinociceptive action of clonidine (Clon) and the interactions with alpha 1, alpha 2 adrenoceptor and opioid receptor antagonists was evaluated in mice by use of chemical algesiometric test (acetic acid writhing test). 2. Clon produced a dose-dependent antinociceptive action and the ED50 for intracerebroventricular (i.c.v.) was lower than for intraperitoneal (i.p.) administration (1 ng kg-1 vs 300 ng kg-1). The parallelism of the dose-response curves indicates activation of a common receptor subtype. 3. Systemic administration of prazosin and terazosin displayed antinociceptive activity. Pretreatment with prazosin produced a dual action: i.c.v. Clon effect did not change, and i.p. Clon effect was enhanced. Yohimbine i.c.v. or i.p. did not induce antinonciception, but antagonized Clon-induced activity. These results suggest that alpha 1- and alpha 2-adrenoceptors, either located at the pre- and/or post-synaptic level, are involved in the control of spinal antinociception. 4. Naloxone (NX) and naltrexone (NTX) induced antinociceptive effects at low doses (microgram kg-1 range) and a lower antinociceptive effect at higher doses (mg kg-1 range). Low doses of NX or NTX antagonized Clon antinociception, possibly in relation to a preferential mu opioid receptor antagonism. In contrast, high doses of NX or NTX increased the antinociceptive activity of Clon, which could be due to an enhanced inhibition of the release of substance P. 5. The results obtained in the present work suggest the involvement of alpha 1-, alpha 2-adrenoceptor and opioid receptors in the modulation of the antinociceptive activity of clonidine, which seems to be exerted either at spinal and/or supraspinal level. PMID:8894177

Sierralta, F.; Naquira, D.; Pinardi, G.; Miranda, H. F.

1996-01-01

331

Role of transient receptor potential vanilloid 4 activation in indomethacin-induced intestinal damage.  

PubMed

Gastrointestinal ulcers and bleeding are serious complications of nonsteroidal anti-inflammatory drug (NSAID) use. Although administration of antibiotics and Toll-like receptor 4 knockdown mitigate NSAID-induced enteropathy, the molecular mechanism of these effects is poorly understood. Intestinal hyperpermeability is speculated to trigger the initial damage due to NSAID use. Transient receptor potential vanilloid 4 (TRPV4) is a nonselective cation channel expressed throughout the gastrointestinal tract epithelium that is activated by temperature, extension, and chemicals such as 5,6-epoxyeicosatrienoic acid (5,6-EET). The aim of this study was to investigate the possible role of TRPV4 in NSAID-induced intestinal damage. TRPV4 mRNA and protein expression was confirmed by RT-PCR and immunochemistry, respectively, in mouse and human tissues while TRPV4 channel activity of the intestinal cell line IEC-6 was assessed by Ca(2+)-imaging analysis. TRPV4 activators or the NSAID indomethacin significantly decreased transepithelial resistance (TER) in IEC-6 cells, and indomethacin-induced TER decreases were inhibited by specific TRPV4 inhibitors or small-interfering RNA TRPV4 knockdown, as well as by the epoxygenase inhibitor N-(methylsulfonyl)-2-(2-propynyloxy)-benzenehexanamide, which decreased 5,6-EET levels. In TRPV4 knockout mice, indomethacin-induced intestinal damage was significantly reduced compared with WT mice. Taken together, these results show that TRPV4 activation in the intestinal epithelium caused epithelial hyperpermeability in response to NSAID-induced arachidonic acid metabolites and contributed to NSAID-induced intestinal damage. Thus, TRPV4 could be a promising new therapeutic target for the prevention of NSAID-induced intestinal damage. PMID:24789205

Yamawaki, Hidemoto; Mihara, Hiroshi; Suzuki, Nobuhiro; Nishizono, Hirofumi; Uchida, Kunitoshi; Watanabe, Shiro; Tominaga, Makoto; Sugiyama, Toshiro

2014-07-01

332

17?-Estradiol-induced cell proliferation requires estrogen receptor (ER) ? monoubiquitination.  

PubMed

Protein monoubiquitination (monoUbq) (i.e., the attachment of one single ubiquitin to the substrate) is a non-proteolytic reversible modification that controls protein functions. Among other proteins, the estrogen receptor ? (ER?), which mediates the pleiotropic effects of the cognate hormone 17?-estradiol (E2), is a monoubiquitinated protein. Although it has been demonstrated that E2 rapidly reduces ER? monoUbq in breast cancer cells, the impact of monoUbq in the regulation of the ER? activities is poorly appreciated. Here, we show that mutation of the ER? monoUbq sites prevents the E2-induced ER? phosphorylation in the serine residue 118 (S118), reduces ER? transcriptional activity, and precludes the ER?-mediated extranuclear activation of signaling pathways (i.e., AKT activation) thus impeding the E2-induced cyclin D1 promoter activation and consequently cell proliferation. In addition, the interference with ER? monoUbq deregulates E2-induced association of ER? to the insulin like growth factor receptor (IGF-1-R). Altogether these data demonstrate an inherent role for monoUbq in ER? signaling and point to the physiological function of ER? monoUbq in the regulation of E2-induced cell proliferation. PMID:21356307

La Rosa, Piergiorgio; Pesiri, Valeria; Marino, Maria; Acconcia, Filippo

2011-07-01

333

Sphingosine 1-phosphate receptor activation enhances BMP-2-induced osteoblast differentiation  

SciTech Connect

Highlights: Black-Right-Pointing-Pointer We investigated the role of S1P signaling for osteoblast differentiation. Black-Right-Pointing-Pointer Both S1P and FTY enhanced BMP-2-stimulated osteoblast differentiation by C2C12 cells. Black-Right-Pointing-Pointer S1P signaling enhanced BMP-2-stimulated Smad and ERK phosphorylation by C2C12 cells. Black-Right-Pointing-Pointer MEK/ERK signaling is a pathway underlying S1P signaling for osteoblast differentiation. -- Abstract: We previously demonstrated that sphingosine 1-phosphate (S1P) receptor-mediated signaling induced proliferation and prostaglandin productions by synovial cells from rheumatoid arthritis (RA) patients. In the present study we investigated the role of S1P receptor-mediated signaling for osteoblast differentiation. We investigated osteoblast differentiation using C2C12 myoblasts, a cell line derived from murine satellite cells. Osteoblast differentiation was induced by the treatment of bone morphogenic protein (BMP)-2 in the presence or absence of either S1P or FTY720 (FTY), a high-affinity agonist of S1P receptors. Osteoblast differentiation was determined by osteoblast-specific transcription factor, Runx2 mRNA expression, alkaline phosphatase (ALP) activity and osteocalcin production by the cells. Smad1/5/8 and extracellular signal-regulated kinase (ERK) 1/2 phosphorylation was examined by Western blotting. Osteocalcin production by C2C12 cells were determined by ELISA. Runx2 expression and ALP activity by BMP-2-stimulated C2C12 cells were enhanced by addition of either S1P or FTY. Both S1P and FTY enhanced BMP-2-induced ERK1/2 and Smad1/5/8 phosphorylation. The effect of FTY was stronger than that of S1P. S1P receptor-mediated signaling on osteoblast differentiation was inhibited by addition of mitogen-activated protein kinase/ERK kinase (MEK) 1/2 inhibitor, indicating that the S1P receptor-mediated MEK1/2-ERK1/2 signaling pathway enhanced BMP-2-Smad signaling. These results indicate that S1P receptor-mediated signaling plays a crucial role for osteoblast differentiation.

Sato, Chieri [Division of Rheumatology, Department of Internal Medicine, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo 663-8501 (Japan)] [Division of Rheumatology, Department of Internal Medicine, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo 663-8501 (Japan); Iwasaki, Tsuyoshi, E-mail: tsuyo-i@huhs.ac.jp [Division of Pharmacotherapy, Department of Pharmacy, School of Pharmacy, Hyogo University of Health Sciences, 1-3-6 Minatojima, Chuo-ku, Kobe 650-8530 (Japan)] [Division of Pharmacotherapy, Department of Pharmacy, School of Pharmacy, Hyogo University of Health Sciences, 1-3-6 Minatojima, Chuo-ku, Kobe 650-8530 (Japan); Kitano, Sachie; Tsunemi, Sachi; Sano, Hajime [Division of Rheumatology, Department of Internal Medicine, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo 663-8501 (Japan)] [Division of Rheumatology, Department of Internal Medicine, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo 663-8501 (Japan)

2012-06-22

334

Effects of BDNF, T3, and corticosterone on expression of the hypothalamic obesity gene network in vivo and in vitro.  

PubMed

Hypothalamic neuropeptides, neurotrophins, and systemic hormones modulate food intake and body composition. Although advances toward elucidating these interactions have been made, many aspects of the underlying mechanisms remain vague. Hypothalami from fat and lean chicken lines were assessed for differential expression of anabolic/orexigenic and catabolic/anorexigenic genes. Effects of triiodothyronine (T(3)), corticosterone (Cort), and brain-derived neurotrophic factor (BDNF) on expression of anabolic/orexigenic and catabolic/anorexigenic genes were tested in cultures of hypothalamic neurons. From this, we found that BDNF increased and T(3) decreased gene expression for BDNF, leptin receptor (LEPR), pro-opiomelanocortin (POMC), thyrotropin releasing hormone (TRH), and agouti-related protein (AGRP). Thyroid hormone levels were manipulated during development to show that T(3) inhibited BDNF, TRH, and BDNF receptor gene expression. Delivery of T(3), Cort, T(3) plus Cort, or vehicle in vivo continuously for 72 h indicated that Cort and T(3) have overlapping roles in regulating TRH, LEPR, and POMC gene expression and that Cort and T(3) regulate BDNF, neuropeptide Y, and AGRP in opposite directions. Collectively, these findings suggest that interactions between the neuropeptide BDNF and the hormones T(3) and/or Cort may constitute a homeostatic mechanism that links hypothalamic energy regulation controlling body composition. PMID:19158410

Byerly, Mardi S; Simon, Jean; Lebihan-Duval, Elisabeth; Duclos, Michel J; Cogburn, Larry A; Porter, Tom E

2009-04-01

335

Roles of Parathyroid Hormone (PTH) Receptor and Reactive Oxygen Species in Hyperlipidemia-Induced PTH(1-34) Resistance in Preosteoblasts.  

PubMed Central

Bioactive lipids initiate inflammatory reactions leading to pathogenesis of atherosclerosis. Evidence shows that they also contribute to bone loss by inhibiting parathyroid hormone receptor (PTH1R) expression and differentiation of osteoblasts. We previously demonstrated that bone anabolic effects of PTH(1-34) are blunted in hyperlipidemic mice and that these PTH effects are restored by antioxidants. However, it is not clear which osteoblastic cell developmental stage is targeted by bioactive lipids. To investigate the effects of hyperlipidemia at the cellular level, hyperlipidemic Ldlr?/? mice were bred with Col3.6GFPtpz mice, in which preosteoblasts/osteoblasts carry a topaz fluorescent label, and with Col2.3GFPcyan mice, in which more mature osteoblasts/osteocytes carry a cyan fluorescent label. Histological analyses of trabecular bone surfaces in femoral as well as calvarial bones showed that intermittent PTH(1-34) increased fluorescence intensity in WT-Tpz mice, but not in Tpz-Ldlr?/? mice. In contrast, PTH(1-34) did not alter fluorescence intensity in femoral cortical envelopes of either WT-Cyan or Ldlr?/?-Cyan mice. To test the mechanism of PTH1R downregulation, preosteoblastic MC3T3-E1 cells were treated with bioactive lipids and the antioxidant Trolox. Results showed that inhibitory effects of PTH1R levels by bioactive lipids were rescued by pretreatment with Trolox. The inhibitory effects on expression of PTH1R as well as on PTH-induced osteoblastic genes were mimicked by xanthine/xanthine oxidase, a known generator of reactive oxygen species. These findings suggest an important role of preosteoblasts as the target development stage and downregulation of PTH receptor expression mediated by intracellular oxidant stress as a mechanism in hyperlipidemia-induced PTH resistance. PMID:24038594

Li, Xin; Garcia, Jamie; Lu, Jinxiu; Iriana, Sidney; Kalajzic, Ivo; Rowe, David; Demer, Linda; Tintut, Yin

2013-01-01

336

Lack of GABAB receptors modifies behavioural and biochemical alterations induced by precipitated nicotine withdrawal.  

PubMed

The nicotine (NIC) withdrawal syndrome is considered to be a major cause of the high relapse rate among individuals undergoing smoking cessation. The aim of the present study was to evaluate a possible role of GABAB receptors in NIC withdrawal, by comparing GABAB1 knockout mice and their wild-type littermates. We analysed the time course of the global withdrawal score, the anxiety-like effects, monoamine concentrations, the brain-derived neurotrophic factor (BDNF) expression, the corticosterone plasmatic levels and [(3)H]epibatidine binding sites during NIC withdrawal precipitated by mecamylamine, a nicotinic receptor antagonist (MEC). In NIC withdrawn wild-type mice, we observed a global withdrawal score, an anxiety-like effect in the elevated plus maze, a decrease of the striatal dopamine and 3,4-dihydroxyphenylacetic acid concentrations, an increase of corticosterone plasma levels, a reduction of BDNF expression in several brain areas and an increase of [(3)H]epibatidine binding sites in specific brain regions. Interestingly, the effects found in NIC withdrawn wild-type mice were absent in GABAB1 knockout mice, suggesting that GABAB1 subunit of the GABAB receptor is involved in the regulation of the behavioural and biochemical alterations induced by NIC withdrawal in mice. These results reveal an interaction between the GABAB receptors and the neurochemical systems through which NIC exerts its long-term effects. PMID:25479464

Varani, Andrés P; Pedrón, Valeria T; Machado, Lirane Moutinho; Antonelli, Marta C; Bettler, Bernhard; Balerio, Graciela N

2015-03-01

337

Attenuation of antagonist-induced impairment of dopamine receptors by L-prolyl-L-leucyl-glycinamide  

SciTech Connect

The present study was undertaken in order to determine whether chronic,long-term postnatal challenge of rat pups per se, with specific dopamine D1 and D2 receptor antagonists, would modify the ontogeny of the respective receptor types. Since the neuropeptide L-prolyl-L-leucyl-glycinamide (PLG) attenuates the effect of haloperidol on dopamine D2 receptors in adult rats it was of interest to determine whether PLG would modulate antagonists-induced alterations in the ontogeny of striatal dopamine D1 and D2 receptors. Half of the rats were treated daily for 32 days from birth with SCH-23390, a selective dopamine D1 antagonist; or spiroperidol, a selective dopamine D2 antagonists; or both SCH-23390 and spiroperidol; or saline. The other half of the litters were treated with PLG, in combination with the other treatments. Animals were decapitated at 5, 8, and 12 weeks from birth for neurochemical analysis of the striatum. Chronic SCH-23390 treatment produced a 70-80% decrease in the binding of ({sup 3}H) SCH-23390 to striatal homogenates. The alteration at 5 weeks was associated with a 78% decrease in the Bmax for ({sup 3}H) SCH-23390 binding, and no change in the K{sub D}. Similarly, at 5, 8, and 12 weeks, chronic spiroperidol treatment reduced the binding of ({sup 3}H) spiroperidol to striatal homogenates by 70-80%.

Saleh, M.I.M.

1988-01-01

338

Spinal cord mechanisms mediating behavioral hyperalgesia induced by neurokinin-1 tachykinin receptor activation in the rostral ventromedial medulla.  

PubMed

Hyperalgesia in animal injury models is linked to activation of descending raphespinal modulatory circuits originating in the rostral ventromedial medulla (RVM). A neurokinin-1 (NK-1) receptor antagonist microinjected into the RVM before or after inflammation produced by complete Freund's adjuvant (CFA) resulted in an attenuation of thermal hyperalgesia. A transient (acute) or a continuous infusion of Substance P (SP) microinjected into the RVM of non-inflamed animals led to similar pain hypersensitivity. Intrathecal pretreatment or post-treatment of a 5-HT3 receptor antagonist (Y-25130 or ondansetron) blocked the SP-induced hyperalgesia. The SP-induced hyperalgesia was both GABA(A) and NMDA receptor-dependent after pre- and post-treatment with selective antagonists at the spinal level. A microinjection of SP into the RVM also led to increased NMDA NR1 receptor subunit phosphorylation in spinal cord tissue. The GABA(A) receptor-mediated hyperalgesia involved a shift in the anionic gradient in dorsal horn nociceptive neurons and an increase in phosphorylated NKCC1 protein (isoform of the Na-K-Cl cotransporter). Following a low dose of SP infused into the RVM, intrathecal muscimol (GABA(A) agonist) increased SP-induced thermal hyperalgesia, phosphorylated NKCC1 protein expression, and NMDA NR1 subunit phosphorylation in the spinal cord. The thermal hyperalgesia was blocked by intrathecal gabazine, the GABA(A) receptor antagonist, and MK-801, the NMDA receptor channel blocker. These findings indicate that NK-1 receptors in the RVM are involved in SP-induced thermal hyperalgesia, this hyperalgesia is 5-HT3-receptor dependent at the spinal level, and involves the functional interaction of spinal GABA(A) and NMDA receptors. PMID:20888891

Lagraize, S C; Guo, W; Yang, K; Wei, F; Ren, K; Dubner, R

2010-12-29

339

Ursolic Acid, a Pentacyclin Triterpene, Potentiates TRAIL-induced Apoptosis through p53-independent Up-regulation of Death Receptors  

PubMed Central

Discovery of the molecular targets of traditional medicine and its chemical footprints can validate the use of such medicine. In the present report, we investigated the effect of ursolic acid (UA), a pentacyclic triterpenoid found in rosemary and holy basil, on apoptosis induced by TRAIL. We found that UA potentiated TRAIL-induced apoptosis in cancer cells. In addition, UA also sensitized TRAIL-resistant cancer cells to the cytokine. When we investigated the mechanism, we found that UA down-regulated cell survival proteins and induced the cell surface expression of both TRAIL receptors, death receptors 4 and 5 (DR4 and -5). Induction of receptors by UA occurred independently of cell type. Gene silencing of either receptor by small interfering RNA reduced the apoptosis induced by UA and the effect of TRAIL. In addition, UA also decreased the expression of decoy receptor 2 (DcR2) but not DcR1. Induction of DRs was independent of p53 because UA induced DR4 and DR5 in HCT116 p53?/? cells. Induction of DRs, however, was dependent on JNK because UA induced JNK, and its pharmacologic inhibition abolished the induction of the receptors. The down-regulation of survival proteins and up-regulation of the DRs required reactive oxygen species (ROS) because UA induced ROS, and its quenching abolished the effect of the terpene. Also, potentiation of TRAIL-induced apoptosis by UA was significantly reduced by both ROS quenchers and JNK inhibitor. In addition, UA was also found to induce the expression of DRs, down-regulate cell survival proteins, and activate JNK in orthotopically implanted human colorectal cancer in a nude mouse model. Overall, our results showed that UA potentiates TRAIL-induced apoptosis through activation of ROS and JNK-mediated up-regulation of DRs and down-regulation of DcR2 and cell survival proteins. PMID:21156789

Prasad, Sahdeo; Yadav, Vivek R.; Kannappan, Ramaswamy; Aggarwal, Bharat B.

2011-01-01

340

A deficiency in the prostaglandin D2 receptor CRTH2 exacerbates adjuvant-induced joint inflammation.  

PubMed

Although the cyclooxygenase metabolites PGs are known to be involved in the progression of arthritis, the role of PGD2 remains unclear. In this study, we evaluated the contribution of signaling mediated through a PGD2 receptor, chemoattractant receptor-homologous molecule expressed on Th2 cells (CRTH2), in the progression of adjuvant-induced joint inflammation. Injection of CFA into the ankle joint stimulated PGD2 production and induced paw swelling in both CRTH2-naive (WT) and CRTH2(-/-) mice. CRTH2(-/-) mice presented more severe arthritic manifestations than did WT mice. Through bone marrow transplantation experiments between WT and CRTH2(-/-) mice, we showed that CRTH2 deficiency in bone marrow-derived immune cells is involved in disease progression. Morphological studies showed that CRTH2 deficiency accelerated the infiltration of macrophages into the inflamed paw. Consistent with this finding, we observed that treatment with the macrophage inactivator GdCl3 or the macrophage-depleting agent liposomal clodronate improved arthritis symptoms in CRTH2(-/-) mice. Adoptive transfer of CRTH2(-/-) macrophages exacerbated joint inflammation in WT mice. In addition, CRTH2 deficiency accelerated, whereas CRTH2 agonism inhibited, the expression of a macrophage-activating cytokine (GM-CSF) and a chemokine receptor (CXCR2) in CFA-treated peritoneal macrophages. Together, these observations demonstrate that PGD2-CRTH2 signaling plays a protective role in joint inflammation by attenuating the infiltration of macrophages. PMID:25362177

Tsubosaka, Yoshiki; Nakamura, Tatsuro; Hirai, Hiroyuki; Hori, Masatoshi; Nakamura, Masataka; Ozaki, Hiroshi; Murata, Takahisa

2014-12-15

341

Receptor Interacting Protein 2 (RIP2) Is Dispensable for OVA-Induced Airway Inflammation in Mice  

PubMed Central

Purpose Asthma is a pulmonary chronic inflammatory disease characterized by airway obstruction and hyperresponsiveness. Pattern recognition receptors are known to play a key role in the development of allergic diseases as well as host defenses against microbial infection. Receptor interacting protein 2 (RIP2), a serine/threonine kinase, is an adaptor molecule of NOD1 and NOD2, and genetic variation in this receptor is known to be associated with the severity of allergic asthma in children. In this study, we examined the role of RIP2 in the development of allergic airway inflammation in a mouse model. Methods Airway inflammation was induced in mice through intranasal administration of ovalbumin (OVA) after 2 intraperitoneal immunizations with OVA. Lung inflammation and mucus hypersecretion were examined histologically and total cell infiltration in bronchoalveolar (BAL) fluids was determined. Levels of the Th2-related cytokines, IL-5 and IL-13, in lung extracts were measured by ELISA. Serum antigen-specific IgE and IgG1 levels were also assessed. Results OVA-induced lung inflammation and mucus hypersecretion were not different between WT and RIP2-deficient mice. The IL-5 and IL-13 levels in the bronchoalveolar (BAL) fluids were also not impaired in RIP2-deficient mice compared to WT mice. Moreover, RIP2 deficiency did not affect serum OVA-specific IgG1 and IgE levels. Conclusions Our results suggest that RIP2 is not associated with the development of allergic airway inflammation. PMID:24587954

Kim, Tae-Hyoun; Park, Yeong-Min; Ryu, Seung-Wook; Kim, Dong-Jae

2014-01-01

342

Sumatriptan-induced saphenous venoconstriction in the anaesthetized dog through 5-HT1-like receptor activation.  

PubMed Central

1. The role of vasoconstrictor 5-HT1-like receptors in the control of vascular reactivity in vivo has been relatively little studied, particularly with regards to venous function. Using an anaesthetized dog model, we have investigated the haemodynamic profile of the selective 5-HT1-like agonist, sumatriptan, focussing on the reactivity of the saphenous venous bed. The key feature of our experimental model was the implantation of ultrasonic crystals on the adventitial surface of the lateral saphenous vein to provide direct and continuous measurement of drug-induced changes in vein diameter. Saphenous vein pressure was measured simultaneously via a proximal branch. 2. Sumatriptan 1-30 micrograms kg-1, i.v., produced pronounced dose-related reductions in saphenous vein diameter which reached congruent to 40% at the highest dose tested. Sumatriptan also produced modest increases in mean blood pressure, total peripheral resistance and left ventricular end diastolic pressure but had little or no effect on cardiac output, heart rate, cardiac contractility or saphenous venous pressure. Sumatriptan-induced reductions in saphenous vein diameter were strongly antagonized by the 5-HT1-receptor antagonist, methiothepin (0.3 mg kg-1, i.v.) but were unaffected by the 5-HT2 antagonist, ketanserin (0.3 mg kg-1, i.v.). 3. Hence, 5-HT1-like receptor stimulation in vivo can result in a powerful local venoconstrictor effect. PMID:8564250

Drieu la Rochelle, C.; O'Connor, S. E.

1995-01-01

343

Pleurocidin, a novel antimicrobial peptide, induces human mast cell activation through the FPRL1 receptor.  

PubMed

Pleurocidins are a novel family of ?-helical cationic antimicrobial peptides (CAPs) that are structurally and functionally similar to cathelicidins, one of the major CAP families. As cathelicidins stimulate mast cell chemotaxis and mediator release, we postulated that pleurocidins similarly activate mast cells. A screen of 20 pleurocidin peptides revealed that some were capable of degranulating the human mast cell line LAD2 (Laboratory of Allergic Diseases 2). Pleurocidin NRC-04 caused LAD2 to adhere, migrate, degranulate, and release cysteinyl leukotrienes and prostaglandin D2. Moreover, pleurocidin increased intracellular Ca(2+) mobilization in mast cells and induced the production of proinflammatory chemokines such as monocyte chemotactic protein-1/C-C motif chemokine ligand 2 (CCL2) and macrophage inflammatory protein-1?/CCL4. Our evaluation of possible cellular mechanisms suggested that G proteins, phosphoinositol-3 kinase (PI3K), phospholipase C (PLC), and phosphokinase C (PKC) were involved in pleurocidin-induced mast cell activation as evidenced by the inhibitory effects of pertussis toxin (G protein inhibitor), wortmanin (PI3K inhibitor), U-73122 (PLC inhibitor), and Ro-31-8220 (PKC inhibitor), respectively. We also found that human mast cells expressed the N-formyl-peptide receptor 1 (FPRL1) receptor and FPRL1-specific inhibitor affected pleurocidin-mediated activation of mast cell. Our finding that the novel CAP pleurocidin activated human mast cell through G protein-coupled receptor signaling suggests that this peptide might have immunomodulatory functions. PMID:23839065

Pundir, P; Catalli, A; Leggiadro, C; Douglas, S E; Kulka, M

2014-01-01

344

Endothelin Receptor Inhibition with Bosentan Delays Onset of Liver Injury in Streptozotocin-Induced Diabetic Condition.  

PubMed

Background: This study was designed to investigate the protective effects of bosentan an orally active non-peptide mixed ETA/ETB receptor antagonist, on liver injury in streptozotocin-induced diabetic rats. Methods: 24 Albino-Wistar rats were randomly divided into 4 groups: healthy (Group 1), diabetic (Group 2) (60?mg/kg of streptozotocin i.p.), diabetic treated with bosentan 50?mg/kg (Group 3) and diabetic treated with bosentan 100?mg/kg (Group 4). The treatment of bosentan was initiated after streptozocin injection and continued for 60 days. Results: Liver from diabetic rats showed significant increase in malondialdehyde (MDA) level and significant decrease in glutathione (GSH), and superoxide dismutase (SOD) activity. Endothelin (ET-1), tumor necrosis factor (TNF-?) and transforming growth factor beta (TGF-?) gene expression significantly increased in the diabetic groups in the rat liver tissue. Bosentan treatment showed a significant up-regulatory effect on ET-1, TNF-? and TGF-? mRNA expression. Results from histopathological evaluation of the liver were in accordance with our biochemical and molecular results. Conclusions: These data provide clear evidence that bosentan treatment is associated with promising hepatoprotective effect against diabetes-induced liver damage via reduction of cell inflammation and oxidative damage. These data suggest that ET receptors may be an important actor in diabetes-related liver damage, and blockage of these receptors may become a target for preventing diabetic complications in the future. PMID:24918345

Demirci, E; Ferah, I; Gundogdu, C; Ozkanlar, S; Baygutalp, N K; Bayir, Y; Calik, M; Ayaz, G

2014-06-11

345

Activation of serotonin 5-HT7 receptor induces coronary flow increase in isolated rat heart.  

PubMed

Serotonin (5-Hydroxytryptamine, 5-HT) can elicit both vasoconstrictive and relaxant responses on rat coronary artery. The constrictive response has been well discussed, but the mechanism of relaxant response is less studied. In the present study, we found serotonin (0.3 and 1?M) increased coronary flow on isolated rat hearts, and treatment of nitric oxide synthase inhibitor NG-nitro-l-arginine methyl ester (l-NAME) 300?M reduced but not totally blocked this coronary flow increasing effect. In l-NAME 10?M treated heart, treatment of selective serotonin 5-HT7 receptor antagonist SB269970 0.1?M blocked serotonin induced coronary flow increasing response, and in the presence of 1?M SB269970, serotonin turned into reducing coronary flow. Treatment of TCW295 (8-(2,4-Dimethoxyphenyl)-6-methoxy-2-phenethyl-1,2,3,4-tetrahydroisoquinolin-7-ol hydrochloride), a novel serotonin 5-HT2A/7 receptor antagonist, inhibited both serotonin induced coronary flow increasing and decreasing effects. In conclusion, we found serotonin increases coronary flow of isolated rat heart by activating serotonin 5-HT7 receptor activation, and this effect can be, at least partially, resistant to l-NAME. PMID:25196212

Chang Chien, Ching-Chia; Hsin, Ling-Wei; Su, Ming-Jai

2015-02-01

346

Adenosine receptor blockade enhances isoproterenol-induced increases in cardiac interstitial adenosine.  

PubMed

The failure of adenosine receptor antagonists to consistently attenuate metabolic coronary vasodilation suggests that adenosine is not a primary regulator of functional hyperemia. An alternative hypothesis, however, is that metabolic stimulation of the heart in the presence of an adenosine receptor antagonist results in enhanced interstitial levels of adenosine which then might overcome the blockade. To test this hypothesis, interstitial levels of adenosine and inosine were estimated by HPLC analysis of fluid which exudes from the epicardial surface of isolated rat hearts perfused with crystalloid solution at constant flow. Isoproterenol infusion (10 nM) produced increases in heart rate, left ventricular systolic pressure, rate of pressure development, myocardial oxygen consumption and adenosine and inosine concentrations of venous effluent and surface exudate and produced decreases in coronary vascular resistance. The presence of the adenosine receptor antagonist, 8-(4-sulfophenyl) theophylline (spT) (100 microM), in the perfusate had little or no effect upon most of the responses to isoproterenol except that it significantly enhanced the isoproterenol-induced increases in adenosine release and adenosine concentrations in the venous effluent and surface exudate. The isoproterenol-induced change in adenosine concentration per unit change in oxygen consumption was approximately 3-fold greater in the presence of spT than in its absence. This extra adenosine production may tend to overcome the competitive blocking effect of spT and help explain why agents such as spT are not always effective in blocking metabolic vasodilation. PMID:1942090

Heller, L J; Dole, W P; Mohrman, D E

1991-08-01

347

The trifunctional protein mediates thyroid hormone receptor-dependent stimulation of mitochondria metabolism.  

PubMed

We previously demonstrated that the thyroid hormone, T(3), acutely stimulates mitochondrial metabolism in a thyroid hormone receptor (TR)-dependent manner. T(3) has also recently been shown to stimulate mitochondrial fatty acid oxidation (FAO). Here we report that TR-dependent stimulation of metabolism is mediated by the mitochondrial trifunctional protein (MTP), the enzyme responsible for long-chain FAO. Stimulation of FAO was significant in cells that expressed a nonnuclear amino terminus shortened TR isoform (sTR(43)) but not in adult fibroblasts cultured from mice deficient in both TR? and TR? isoforms (TR?(-/-)?(-/-)). Mouse embryonic fibroblasts deficient in MTP (MTP(-/-)) did not support T(3)-stimulated FAO. Inhibition of fatty-acid trafficking into mitochondria using the AMP-activated protein kinase inhibitor 6-[4-(2-piperidin-1-yl-ethoxy)-phenyl)]-3-pyridin-4-yl-pyrrazolo[1,5-a]-pyrimidine (compound C) or the carnitine palmitoyltransferase 1 inhibitor etomoxir prevented T(3)-stimulated FAO. However, T(3) treatment could increase FAO when AMP-activated protein kinase was maximally activated, indicating an alternate mechanism of T(3)-stimulated FAO exists, even when trafficking is presumably high. MTP? protein levels and higher molecular weight complexes of MTP subunits were increased by T(3) treatment. We suggest that T(3)-induced increases in mitochondrial metabolism are at least in part mediated by a T(3)-shortened TR isoform-dependent stabilization of the MTP complex, which appears to lower MTP subunit turnover. PMID:22570332

Chocron, E Sandra; Sayre, Naomi L; Holstein, Deborah; Saelim, Nuttawut; Ibdah, Jamal A; Dong, Lily Q; Zhu, Xuguang; Cheng, Sheue-Yann; Lechleiter, James D

2012-07-01

348

The Trifunctional Protein Mediates Thyroid Hormone Receptor-Dependent Stimulation of Mitochondria Metabolism  

PubMed Central

We previously demonstrated that the thyroid hormone, T3, acutely stimulates mitochondrial metabolism in a thyroid hormone receptor (TR)-dependent manner. T3 has also recently been shown to stimulate mitochondrial fatty acid oxidation (FAO). Here we report that TR-dependent stimulation of metabolism is mediated by the mitochondrial trifunctional protein (MTP), the enzyme responsible for long-chain FAO. Stimulation of FAO was significant in cells that expressed a nonnuclear amino terminus shortened TR isoform (sTR43) but not in adult fibroblasts cultured from mice deficient in both TR? and TR? isoforms (TR??/???/?). Mouse embryonic fibroblasts deficient in MTP (MTP?/?) did not support T3-stimulated FAO. Inhibition of fatty-acid trafficking into mitochondria using the AMP-activated protein kinase inhibitor 6-[4-(2-piperidin-1-yl-ethoxy)-phenyl)]-3-pyridin-4-yl-pyrrazolo[1,5-a]-pyrimidine (compound C) or the carnitine palmitoyltransferase 1 inhibitor etomoxir prevented T3-stimulated FAO. However, T3 treatment could increase FAO when AMP-activated protein kinase was maximally activated, indicating an alternate mechanism of T3-stimulated FAO exists, even when trafficking is presumably high. MTP? protein levels and higher molecular weight complexes of MTP subunits were increased by T3 treatment. We suggest that T3-induced increases in mitochondrial metabolism are at least in part mediated by a T3-shortened TR isoform-dependent stabilization of the MTP complex, which appears to lower MTP subunit turnover. PMID:22570332

Chocron, E. Sandra; Sayre, Naomi L.; Holstein, Deborah; Saelim, Nuttawut; Ibdah, Jamal A.; Dong, Lily Q.; Zhu, Xuguang; Cheng, Sheue-Yann

2012-01-01

349

Attenuation of methamphetamine-induced effects through the antagonism of sigma (?) receptors: evidence from in vivo and in vitro studies  

PubMed Central

Methamphetamine (METH) and many other abused substances interact with ? receptors. ? Receptors are found on dopaminergic neurons and can modulate dopaminergic neurotransmission. Antisense knock down of ? receptors also mitigates METH-induced stimulant effects, suggesting that these proteins are viable medication development targets for treating pscyhostimulant abuse. In the present study, AC927, a ? receptor antagonist, was evaluated for its ability to attenuate METH-induced effects in vivo and in vitro. Radioligand binding studies showed that AC927 had preferential affinity for ? receptors compared to 29 other receptors, transporters and ion channels. Pretreatment of male, Swiss Webster mice with AC927 significantly attenuated METH-induced locomotor stimulation, striatal dopamine depletions, striatal dopamine transporter reductions, and hyperthermia. When the neurotoxicity of METH was further examined in vitro under temperature-controlled conditions, co-incubation with AC927 mitigated METH-induced cytotoxicity. Together, the results demonstrate that AC927 protects against METH-induced effects, and suggests a new strategy for treating psychostimulant abuse. PMID:18755577

Matsumoto, Rae R.; Shaikh, Jamaluddin; Wilson, Lisa L.; Vedam, Shreedeepalakshmi; Coop, Andrew

2008-01-01

350

Serotonergic-postsynaptic receptors modulate gripping-induced immobility episodes in male taiep rats.  

PubMed

The Taiep rat is a myelin mutant with a motor syndrome characterized by tremor, ataxia, immobility, epilepsy, and paralysis. The rat shows a hypomyelination followed by a progressive demyelination. During immobilities taiep rats show a REM-like sleep pattern and a disorganized sleep-wake pattern suggesting taiep rats as a model of narcolepsy-cataplexy. Our study analyzed the role of postsynaptic serotonin receptors in the expression of gripping-induced immobility episodes (IEs) in 8-month-old male taiep rats. The specific postsynaptic serotonin agonist +/-1-(2,5-dimethoxy-4-iodoamphetamine hydrochloride (+/-DOI) decreased the frequency of gripping-induced IEs, but that was not the case with alpha-methyl-serotonin maleate (alpha-methyl-5HT), a nonspecific postsynaptic agonist. Although the serotonin antagonists, ketanserine and metergoline, produced a biphasic effect, first a decrease followed by an increase with higher doses, similar effects were obtained with a mean duration of gripping-induced IEs. These findings correlate with the pharmacological observations in narcoleptic dogs and humans in which serotonin-reuptake inhibitors improve cataplexy, particularly in long-term treatment that could change the serotonin receptor levels. Polysomnographic recordings showed an increase in the awakening time and a decrease in the slow wave and rapid eye movement sleep concomitant with a decrease in immobilities after use of +/-DOI, this being stronger with the highest dose. Taken together, our results show that postsynaptic serotonin receptors are involved in the modulation in gripping-induced IEs caused by the changes in the organization of the sleep-wake cycle in taiep rats. It is possible that specific agonists, without side effects, could be a useful treatment in human narcoleptic patients. PMID:19484723

Eguibar, José R; Cortés, M C; Ita, M L

2009-09-01

351

Complex Human Glucocorticoid Receptor dim Mutations Define Glucocorticoid Induced Apoptotic Resistance in Bone Cells  

PubMed Central

A mutation in the D-loop of the second zinc finger of the DNA-binding domain of the human glucocorticoid receptor (hGR), A458T (GRdim), has been suggested to be essential for dimerization and DNA binding of the GR, and genetically altered GRdim mice survive, whereas murine GR knockout mice die. Interestingly, thymocytes isolated from the GRdim mice were reported to be resistant to glucocorticoid-induced apoptosis. To further evaluate the dim mutations in glucocorticoid-induced apoptosis, we stably expressed either the hGRdim (A458T) or the hGRdim4 (A458T, R460D, D462C, and N454D) mutant receptors in human osteosarcoma (U-2 OS) cells that are devoid of hGR and unresponsive to glucocorticoids. We analyzed these cell lines by comparison with a stable expression hGR? U-2 OS cell line, which undergoes apoptosis after glucocorticoid treatment. Transient reporter gene assays with glucocorticoid response element-driven vectors revealed that the hGRdim mutation had diminished steroid responsiveness and cells carrying the hGRdim4 mutation were unresponsive to steroid, whereas glucocorticoid-induced nuclear factor ?B repression was unaffected by either mutation. Interestingly, both the hGRdim and hGRdim4 receptors readily formed dimers as measured by immunoprecipitation. Examination of GR-mediated apoptosis showed that hGRdim cells were only partially resistant to apoptosis, whereas hGRdim4 cells were completely resistant to glucocorticoid-induced cell death despite remaining sensitive to other apoptotic stimuli. Global gene expression analysis revealed that hGRdim4 cells widely regulated gene expression but differentially regulated apoptotic mRNA when compared with cells expressing wild-type hGR?. These studies challenge conclusions drawn from previous studies of GR dim mutants. PMID:22174376

Scoltock, Alyson B.; Hamel, Brant L.; Yudt, Matthew R.; Cidlowski, John A.

2012-01-01

352

[18F]FDG-PET as an imaging biomarker to NMDA receptor antagonist-induced neurotoxicity.  

PubMed

Positron emission tomography (PET) is an effective tool for noninvasive examination of the body and provides a range of functional information. PET imaging with [(18)F]fluoro-2-deoxy-d-glucose ([(18)F]FDG) has been used to image alterations in glucose metabolism in brain or cancer tissue in the field of clinical diagnosis but not in the field of toxicology. A single dose of N-methyl-d-aspartate (NMDA) receptor antagonist induces neuronal cell degeneration/death in the rat retrosplenial/posterior cingulate (RS/PC) cortex region. These antagonists also increase local cerebral glucose utilization. Here, we examined the potential of [(18)F]FDG-PET as an imaging biomarker of neurotoxicity induced by an NMDA receptor antagonist, MK-801. Using [(18)F]FDG-PET, we determined that increased glucose utilization involved the neurotoxicity induced by MK-801. The accumulation of [(18)F]FDG was increased in the rat RS/PC cortex region showing neuronal cell degeneration/death and detected before the onset of neuronal cell death. This effect increased at a dose level at which neuronal cell degeneration recovered 24h after MK-801 administration. Scopolamine prevented the neurotoxicity and [(18)F]FDG accumulation induced by MK-801. Furthermore, in cynomolgus monkeys that showed no neuronal cell degeneration/death when treated with MK-801, we noted no differences in [(18)F]FDG accumulation between test and control subjects in any region of the brain. These findings suggest that [(18)F]FDG-PET, which is available for clinical trials, may be useful in generating a predictive imaging biomarker for detecting neurotoxicity against NMDA receptor antagonists with the same pharmacological activity as MK-801. PMID:23457119

Shirakawa, Takafumi; Mitsuoka, Keisuke; Kuroda, Kanae; Miyoshi, Sosuke; Shiraki, Katsuhisa; Naraoka, Hitoshi; Noda, Akihiro; Fujikawa, Akihiko; Fujiwara, Michio

2013-05-01

353

Bradykinin inducible receptor is essential to lipopolysaccharide-induced acute lung injury in mice.  

PubMed

Lipopolysaccharides from gram-negative bacteria are amongst the most common causative agents of acute lung injury, which is characterized by an inflammatory response, with cellular infiltration and the release of mediators/cytokines. There is evidence that bradykinin plays a role in lung inflammation in asthma but in other types of lung inflammation its role is less clear. In the present study we evaluated the role of the bradykinin B1 receptor in acute lung injury caused by lipopolysaccharide inhalation and the mechanisms behind bradykinin actions participating in the inflammatory response. We found that in C57Bl/6 mice, the bradykinin B1 receptor expression was up-regulated 24h after lipopolysaccharide inhalation. At this time, the number of cells and protein concentration were significantly increased in the bronchoalveolar lavage fluid and the mice developed airway hyperreactivity to methacholine. In addition, there was an increased expression of tumor necrosis factor-alpha, interleukin-1 beta and interferon-gamma and chemokines (monocytes chemotactic protein-1 and KC) in the bronchoalveolar lavage fluid and in the lung tissue. We then treated the mice with a bradykinin B1 receptor antagonist, R-954 (Ac-Orn-[Oic2, alpha-MePhe5, D-betaNal7, Ile8]desArg9-bradykinin), 30 min after lipopolysaccharide administration. We observed that this treatment prevented the airway hyperreactivity as well as the increased cellular infiltration and protein content in the bronchoalveolar lavage fluid. Moreover, R-954 inhibited the expression of cytokines/chemokines. These results implicate bradykinin, acting through B1 receptor, in the development of acute lung injury caused by lipopolysaccharide inhalation. PMID:20153312

Campanholle, Gabriela; Landgraf, Richardt G; Borducchi, Erica; Semedo, Patricia; Wang, Pamela H M; Amano, Mariane T; Russo, Momtchilo; Pacheco-Silva, Alvaro; Jancar, Sonia; Camara, Niels O S

2010-05-25

354

Thyroid Hormone Regulation of Gene Expression in Primary Cerebrocortical Cells: Role of Thyroid Hormone Receptor Subtypes and Interactions with Retinoic Acid and Glucocorticoids  

PubMed Central

The effects of thyroid hormone on brain development and function are largely mediated by the binding of 3,5,3?-triiodo-L-thyronine (T3) to its nuclear receptors (TR) to regulate positively or negatively gene expression. We have analyzed by quantitative polymerase chain reaction the effect of T3 on primary cultured cells from the embryonic mouse cerebral cortex, on the expression of Hr, Klf9, Shh, Dio3, Aldh1a1, and Aldh1a3. In particular we focused on T3 receptor specificity, and on the crosstalk between T3, retinoic acid and dexamethasone. To check for receptor subtype specificity we used cerebrocortical cells derived from wild type mice and from mice deficient in thyroid hormone receptor subtypes. Receptor subtype specificity was found for Dio3 and Aldh1a1, which were induced by T3 only in cells expressing the T3 receptor alpha 1 subtype. Interactions of T3 with retinoic acid signaling through the control of retinoic acid metabolism are likely to be important during development. T3 had opposing influences on retinoic acid synthesizing enzymes, increasing the expression of Aldh1a1, and decreasing Aldh1a3, while increasing the retinoic acid degrading enzyme Cyp26b1. Dexamethasone increased Klf9 and Aldh1a1 expression. The effects of T3 and dexamethasone on Aldh1a1 were highly synergistic, with mRNA increments of up to 20 fold. The results provide new data on thyroid hormone regulation of gene expression and underscore the importance of thyroid hormone interactions with retinoic acid and glucocorticoids during neural development. PMID:24618783

Gil-Ibáñez, Pilar; Bernal, Juan; Morte, Beatriz

2014-01-01

355

Thyroid hormone regulation of gene expression in primary cerebrocortical cells: role of thyroid hormone receptor subtypes and interactions with retinoic acid and glucocorticoids.  

PubMed

The effects of thyroid hormone on brain development and function are largely mediated by the binding of 3,5,3'-triiodo-L-thyronine (T3) to its nuclear receptors (TR) to regulate positively or negatively gene expression. We have analyzed by quantitative polymerase chain reaction the effect of T3 on primary cultured cells from the embryonic mouse cerebral cortex, on the expression of Hr, Klf9, Shh, Dio3, Aldh1a1, and Aldh1a3. In particular we focused on T3 receptor specificity, and on the crosstalk between T3, retinoic acid and dexamethasone. To check for receptor subtype specificity we used cerebrocortical cells derived from wild type mice and from mice deficient in thyroid hormone receptor subtypes. Receptor subtype specificity was found for Dio3 and Aldh1a1, which were induced by T3 only in cells expressing the T3 receptor alpha 1 subtype. Interactions of T3 with retinoic acid signaling through the control of retinoic acid metabolism are likely to be important during development. T3 had opposing influences on retinoic acid synthesizing enzymes, increasing the expression of Aldh1a1, and decreasing Aldh1a3, while increasing the retinoic acid degrading enzyme Cyp26b1. Dexamethasone increased Klf9 and Aldh1a1 expression. The effects of T3 and dexamethasone on Aldh1a1 were highly synergistic, with mRNA increments of up to 20 fold. The results provide new data on thyroid hormone regulation of gene expression and underscore the importance of thyroid hormone interactions with retinoic acid and glucocorticoids during neural development. PMID:24618783

Gil-Ibáñez, Pilar; Bernal, Juan; Morte, Beatriz

2014-01-01

356

Role of B61, the Ligand for the Eck Receptor Tyrosine Kinase, in TNF- ?-Induced Angiogenesis  

NASA Astrophysics Data System (ADS)

B61, a cytokine-inducible endothelial gene product, is the ligand for the Eck receptor protein tyrosine kinase (RPTK). Expression of a B61-immunoglobulin chimera showed that B61 could act as an angiogenic factor in vivo and a chemoattractant for endothelial cells in vitro. The Eck RPTK was activated by tumor necrosis factor-? (TNF-?) through induction of B61, and an antibody to B61 attenuated angiogenesis induced by TNF-? but not by basic fibroblast growth factor. This finding suggests the existence of an autocrine or paracrine loop involving activation of the Eck RPTK by its inducible ligand B61 after an inflammatory stimulus, the net effect of which would be to promote angiogenesis, a hallmark of chronic inflammation.

Pandey, Akhilesh; Shao, Haining; Marks, Rory M.; Polverini, Peter J.; Dixit, Vishva M.

1995-04-01

357

Toll-like receptor 4 implicated in acute lung injury induced by paraquat poisoning in mice  

PubMed Central

Objective: To investigate the possible relationship and mechanism of Toll-like receptor 4 (TLR4) and acute lung injury induced by paraquat (PQ) poisoning. Methods: Male wild type mice and male TLR4-knockout mice were used in this study. After paraquat treatment for 24 hours, mice were euthanized and pathology, TLR4 expression and pro-inflammatory cytokines were evaluated. Results: Wild type mice showed deteriorated lung injury, pathological damages and increased TLR4 expression and pulmonary TNF-?, IL-1? and NF-?B p65 levels after PQ treatment. TLR4-deficient mice were significantly resistant to paraquat-induced lung injury. Conclusion: TLR4 may be required as a mediator and may play an important role in acute lung injury induced by paraquat. PMID:25419373

Liu, Wei; Shan, Li-Ping; Dong, Xue-Song; Liu, Zhi

2014-01-01

358

Parathyroid hormone induces the Nrna family of nuclear orphan receptors in vivo  

SciTech Connect

Parathyroid hormone (PTH) has both anabolic and catabolic effects on bone metabolism, although the molecular mechanisms mediating these effects are largely unknown. Among the transcription factors induced by Pth in osteoblasts are the nerve growth factor-inducible factor B (NR4A; NGFI-B) family of orphan nuclear receptors: Nurr1, Nur77, and NOR-1. PTH induces NR4A members through the cAMP-protein kinase A (PKA) pathway in vitro. We report here that PTH rapidly and transiently induced expression of all three NR4A genes in PTH-target tissues in vivo. In calvaria, long bones, and kidneys, NR4A induction was maximal 0.5-1 h after a single intraperitoneal (i.p.) injection of 80 {mu}g/kg PTH. Nur77 demonstrated the highest expression, followed, in order, by Nurr1 and NOR-1. In calvaria and long bone, PTH-induced expression of each NR4A gene was detectable at 10 {mu}g/kg i.p. with maximum induction at 40-80 {mu}g/kg. PTH (3-34) did not induce NR4A mRNA levels in calvaria, long bone, and kidney in vivo, confirming our in vitro results that NR4A genes are induced primarily through the cAMP-PKA pathway. The magnitude of PTH-induced NR4A expression was comparable in vivo and in vitro. However, NR4A mRNA levels peaked and returned to baseline faster in vivo. Both in vivo and in vitro, PTH induced NR4A pre-mRNA levels suggesting that induction of these genes is, at least in part, through activation of mRNA synthesis. The in vivo induction of the NR4A family members by PTH suggests their involvement in, at least some, PTH-induced changes in bone metabolism.

Pirih, Flavia Q. [Division of Diagnostic and Surgical Sciences, UCLA School of Dentistry, Los Angeles, CA 90095 (United States)]. E-mail: fqpirih@ucla.edu; Aghaloo, Tara L. [Division of Diagnostic and Surgical Sciences, UCLA School of Dentistry, Los Angeles, CA 90095 (United States)]. E-mail: taghaloo@ucla.edu; Bezouglaia, Olga [Division of Diagnostic and Surgical Sciences, UCLA School of Dentistry, Los Angeles, CA 90095 (United States)]. E-mail: obezougl@ucla.edu; Nervina, Jeanne M. [Section of Orthodontics, UCLA School of Dentistry, Los Angeles, CA 90095 (United States)]. E-mail: jnervina@ucla.edu; Tetradis, Sotirios [Division of Diagnostic and Surgical Sciences, UCLA School of Dentistry, Los Angeles, CA 90095 (United States); UCLA Molecular Biology Institute, Los Angeles, CA 90095 (United States); E-mail: sotirist@dent.ucla.edu

2005-07-01

359

Pathogen recognition receptors in channel catfish: II. Identification, phylogeny and expression of retinoic acid-inducible gene I (RIG-I)-like receptors (RLRs).  

PubMed

Vertebrates including teleost fish have evolved an array of pathogen recognition receptors (PRRs) for detecting and responding to various pathogen-associated molecular patterns (PAMPs), including Toll-like receptors (TLRs), nucleotide-binding domain, leucine-rich repeat containing receptors (NLRs), and the retinoic acid inducible gene I (RIG-I) like