共查询到20条相似文献,搜索用时 15 毫秒
1.
Jason M. Conley Hongmao Sun Kristin L. Ayers Hu Zhu Rong Chen Min Shen Matthew D. Hall Hongxia Ren 《The Journal of biological chemistry》2021,297(1)
GPR17 is a G-protein-coupled receptor (GPCR) implicated in the regulation of glucose metabolism and energy homeostasis. Such evidence is primarily drawn from mouse knockout studies and suggests GPR17 as a potential novel therapeutic target for the treatment of metabolic diseases. However, links between human GPR17 genetic variants, downstream cellular signaling, and metabolic diseases have yet to be reported. Here, we analyzed GPR17 coding sequences from control and disease cohorts consisting of individuals with adverse clinical metabolic deficits including severe insulin resistance, hypercholesterolemia, and obesity. We identified 18 nonsynonymous GPR17 variants, including eight variants that were exclusive to the disease cohort. We characterized the protein expression levels, membrane localization, and downstream signaling profiles of nine GPR17 variants (F43L, V96M, V103M, D105N, A131T, G136S, R248Q, R301H, and G354V). These nine GPR17 variants had similar protein expression and subcellular localization as wild-type GPR17; however, they showed diverse downstream signaling profiles. GPR17-G136S lost the capacity for agonist-mediated cAMP, Ca2+, and β-arrestin signaling. GPR17-V96M retained cAMP inhibition similar to GPR17-WT, but showed impaired Ca2+ and β-arrestin signaling. GPR17-D105N displayed impaired cAMP and Ca2+ signaling, but unaffected agonist-stimulated β-arrestin recruitment. The identification and functional profiling of naturally occurring human GPR17 variants from individuals with metabolic diseases revealed receptor variants with diverse signaling profiles, including differential signaling perturbations that resulted in GPCR signaling bias. Our findings provide a framework for structure–function relationship studies of GPR17 signaling and metabolic disease. 相似文献
2.
Stefan Broselid Kelly A. Berg Teresa A. Chavera Robin Kahn William P. Clarke Bj?rn Olde L. M. Fredrik Leeb-Lundberg 《The Journal of biological chemistry》2014,289(32):22117-22127
GPR30, or G protein-coupled estrogen receptor, is a G protein-coupled receptor reported to bind 17β-estradiol (E2), couple to the G proteins Gs and Gi/o, and mediate non-genomic estrogenic responses. However, controversies exist regarding the receptor pharmacological profile, effector coupling, and subcellular localization. We addressed the role of the type I PDZ motif at the receptor C terminus in receptor trafficking and coupling to cAMP production in HEK293 cells and CHO cells ectopically expressing the receptor and in Madin-Darby canine kidney cells expressing the native receptor. GPR30 was localized both intracellularly and in the plasma membrane and subject to limited basal endocytosis. E2 and G-1, reported GPR30 agonists, neither stimulated nor inhibited cAMP production through GPR30, nor did they influence receptor localization. Instead, GPR30 constitutively inhibited cAMP production stimulated by a heterologous agonist independently of Gi/o. Moreover, siRNA knockdown of native GPR30 increased cAMP production. Deletion of the receptor PDZ motif interfered with inhibition of cAMP production and increased basal receptor endocytosis. GPR30 interacted with membrane-associated guanylate kinases, including SAP97 and PSD-95, and protein kinase A-anchoring protein (AKAP) 5 in the plasma membrane in a PDZ-dependent manner. Knockdown of AKAP5 or St-Ht31 treatment, to disrupt AKAP interaction with the PKA RIIβ regulatory subunit, decreased inhibition of cAMP production, and St-Ht31 increased basal receptor endocytosis. Therefore, GPR30 forms a plasma membrane complex with a membrane-associated guanylate kinase and AKAP5, which constitutively attenuates cAMP production in response to heterologous agonists independently of Gi/o and retains receptors in the plasma membrane. 相似文献
3.
We developed a colorimetric assay to quantify clavulanic acid (CA) in culture broth of Streptomyces clavuligerus, to facilitate screening of a large number of S. clavuligerus mutants. The assay is based on a β-lactamase-catalyzed reaction, in which the yellow substrate nitrocefin (λ
max=390 nm) is converted to a red product (λ
max=486 nm). Since CA can irreversibly inhibit β-lactamase activity, the level of CA in a sample can be measured as a function
of the A
390/A
486 ratio in the assay mixture. The sensitivity and detection window of the assay were determined to be 50 μg L−1 and 50 μg L−1 to 10 mg L−1, respectively. The reliability of the assay was confirmed by comparing assay results with those obtained by HPLC. The assay
was used to screen a pool of 65 S. clavuligerus mutants and was reliable for identifying CA over-producing mutants. Therefore, the assay saves time and labor in large-scale
mutant screening and evaluation tasks. The detection window and the reliability of this assay are markedly better than those
of previously reported CA assays. This assay method is suitable for high throughput screening of microbial samples and allows
direct visual observation of CA levels on agar plates. 相似文献
4.
Guanine nucleotides modulate the function of chemotactic cyclic AMP receptors inDictyostelium discoideum 总被引:3,自引:0,他引:3
Pim M. W. Janssens Peter L. J. van der Geer Jos C. Arents Roel van Driel 《Molecular and cellular biochemistry》1985,67(2):119-124
Summary Guanosine di- and triphosphates specifically decrease the affinity of chemotactic cAMP receptors in isolatedDictyostelium discoideum membranes. The K0.5 was increased from 50 nM to 150 nM. Receptors were shown to be heterogeneous in dissociation kinetics. In the absence of
guanine nucleotides three dissociation processes could be resolved, having first order rate constants of 8.7 x 10−4, 1.3 X 10−2, and higher than 0.1 s−1. Guanine nucleotides decreased the affinity for cAMP by transforming the slowest dissociating receptor form (KD is 8 nM) to forms dissociating more rapidly. Our data indicate that a guanine nucleotide binding protein (G-protein) is involved
in the transduction of the cAMP signal inD. discoideum. 相似文献
5.
Elena Nobili Elena Tremoli Patrizia Rosa Maurizio Pesce 《Journal of cellular and molecular medicine》2014,18(9):1785-1796
GPR17 is a Gi-coupled dual receptor activated by uracil-nucleotides and cysteinyl-leukotrienes. These mediators are massively released into hypoxic tissues. In the normal heart, GPR17 expression has been reported. By contrast, its role in myocardial ischaemia has not yet been assessed. In the present report, the expression of GPR17 was investigated in mice before and at early stages after myocardial infarction by using immunofluorescence, flow cytometry and RT-PCR. Before induction of ischaemia, results indicated the presence of the receptor in a population of stromal cells expressing the stem-cell antigen-1 (Sca-1). At early stages after ligation of the coronary artery, the receptor was expressed in Sca-1+ cells, and cells stained with Isolectin-B4 and anti-CD45 antibody. GPR17+ cells also expressed mesenchymal marker CD44. GPR17 function was investigated in vitro in a Sca-1+/CD31− cell line derived from normal hearts. These experiments showed a migratory function of the receptor by treatment with UDP-glucose and leukotriene LTD4, two GPR17 pharmacological agonists. The GPR17 function was finally assessed in vivo by treating infarcted mice with Cangrelor, a pharmacological receptor antagonist, which, at least in part, inhibited early recruitment of GPR17+ and CD45+ cells. These findings suggest a regulation of heart-resident mesenchymal cells and blood-borne cellular species recruitment following myocardial infarction, orchestrated by GPR17. 相似文献
6.
Summary It is known that estrogen can protect neurons from excitotoxicity. Since isoflavones possess estrogen-like activity, it is
of interest to determine whether isoflavones can also protect neurons from glutamate-induced neuronal injury. Morphological
observation and lactate dehydrogenase (LDH) release assay were used to estimate the cellular damage. It is surprising that,
contrary to estrogen, isoflavones, specifically genistein and daidzein, are toxic to primary neuronal culture at high concentration.
Treatment of neurons with 50 μM genistein and daidzein for 24 h increased LDH release by 90% and 67%, respectively, indicating a significant cellular damage.
Under the same conditions, estrogen such as 17β-estradiol did not show any effect on primary culture of brain cells. At 100 μM, both genistein and daidzein increased LDH release by 2.6- and 3-fold, respectively with a 30-min incubation. Furthermore,
both genistein and daidzein at 50 μM increased the intracellular calcium level, [Ca2+]i, significantly. To determine their mode of action, genistein and daidzein were tested on glutamate and GABAA receptor binding. Both genistein and daidzein were found to have little effect on glutamate receptor binding, while the binding
of [3H]muscimol to GABAA receptors was markedly inhibited. However, 17β-estradiol did not affect GABAA receptor binding suggesting that the toxic effect of genistein and daidzein could be due to their inhibition of the GABAA receptor resulting in further enhancement of excitation by glutamate and leading to cellular damage.
Ying Jin, Heng Wu contributed equally to this article. 相似文献
7.
Shigeru Yoshida Takahide Ohishi Tetsuo Matsui Masayuki Shibasaki 《Biochemical and biophysical research communications》2010,400(3):437-441
The G protein-coupled receptor 119 (GPR119) is highly expressed in pancreatic β-cells. On activation, this receptor enhances the effect of glucose-stimulated insulin secretion (GSIS) via the elevation of intracellular cAMP concentrations. Although GPR119 agonists represent promising oral antidiabetic agents for the treatment of type 2 diabetes therapy, they suffer from the inability to adequately directly preserve β-cell function. To identify a new structural class of small-molecule GPR119 agonists with both GSIS and the potential to preserve β-cell function, we screened a library of synthetic compounds and identified a candidate molecule, AS1269574, with a 2,4,6-tri-substituted pyrimidine core. Here, we examined the preliminary in vitro and in vivo effects of AS1269574 on insulin secretion and glucose tolerance. AS1269574 had an EC50 value of 2.5 μM in HEK293 cells transiently expressing human GPR119 and enhanced insulin secretion in the mouse pancreatic β-cell line MIN-6 only under high-glucose (16.8 mM) conditions. This contrasted with the action of the sulfonylurea glibenclamide, which also induced insulin secretion under low-glucose conditions (2.8 mM). In in vivo studies, a single administration of AS1269574 to normal mice reduced blood glucose levels after oral glucose loading based on the observed insulin secretion profiles. Significantly, AS1269574 did not affect fed and fasting plasma glucose levels in normal mice. Taken together, these results suggest that AS1269574 represents a novel structural class of small molecule, orally administrable GPR119 agonists with GSIS and promising potential for the treatment of type 2 diabetes. 相似文献
8.
Jia Huang Tomohiro Hamasaki Yoshihisa Ozoe 《Archives of insect biochemistry and physiology》2010,73(2):74-86
Series of agonists and antagonists were examined for their actions on a Bombyx moriα‐adrenergic‐like octopamine receptor (OAR) stably expressed in HEK‐293 cells. The rank order of potency of the agonists was clonidine>naphazoline>tolazoline in Ca2+ mobilization assays, and that of the antagonists was chlorpromazine>yohimbine. These findings suggest that the B. mori OAR is more closely related to the class‐1 OAR in the intact tissue than to the other classes. N′‐(4‐Chloro‐o‐tolyl)‐N‐methylformamidine (DMCDM) and 2‐(2,6‐diethylphenylimino)imidazolidine (NC‐5) elevated the intracellular calcium concentration ([Ca2+]i) with EC50s of 92.8 µM and 15.2 nM, respectively. DMCDM and NC‐5 led to increases in intracellular cAMP concentration ([cAMP]i) with EC50s of 234 nM and 125 nM, respectively. The difference in DMCDM potencies between the cAMP and Ca2+ assays might be due to “functional selectivity.” The Ca2+ and cAMP assay results for DMCDM suggest that the elevation of [cAMP]i, but not that of [Ca2+]i, might account for the insecticidal effect of formamidine insecticides. © 2009 Wiley Periodicals, Inc. 相似文献
9.
Ibragim Gaidarov Xiaohua Chen Todd Anthony Dominique Maciejewski-Lenoir Chen Liaw David J. Unett 《Cellular signalling》2013,25(10):2003-2016
Until recently, the anti-atherosclerotic effects of niacin were attributed primarily to its lipid modification properties mediated by adipocyte G-protein coupled receptor GPR109A, though recent studies have raised significant doubts about this mechanism. In fact, in rodents it has recently been demonstrated that niacin inhibits progression of atherosclerosis through actions on immune cells, particularly via macrophage-expressed GPR109A, independent of lipid-modifying properties. Here, we studied GPR109A signal transduction in human Langerhans cells, macrophages and adipocytes. We find that the consequences of receptor activation are profoundly influenced by cellular context and that ligand-biased signaling significantly impacts functionally relevant signaling. In Langerhans cells, niacin initiates GPR109A-mediated signaling pathways (Erk1/2 and Ca2 +) responsible for the release of vasodilatory prostanoids, while the synthetic GPR109A agonist MK-0354 fails to elicit any signaling, providing a mechanistic basis for the latter compound's inability to cause flushing. While GPR109A mediates inhibition of cAMP in adipocytes, in macrophages GPR109A signaling via Gβγ subunits results in paradoxical augmentation of intracellular cAMP levels. Also, in macrophages niacin and GPR109A full agonists induce Erk1/2 and Ca2 + signaling, release of prostanoids, upregulation of cholesterol transporters ABCA1 and ABCG1 and stimulation of reverse cholesterol transport in GPR109A dependent manner. A mechanism is presented in which signals from the autocrine action of released prostanoids and Gi protein mediated cAMP augmentation are integrated leading to modulation of reverse cholesterol transport regulatory components. These studies provide key insights into mechanisms by which GPR109A may influence cholesterol efflux in macrophages; a process that may be at least partially responsible for niacin's anti-atherosclerotic activity. MK-0354 does not induce niacin-like GPR109A signaling in macrophages, suggesting that biased agonists devoid of the flushing side-effect may also lack properties required for macrophage-mediated anti-atherosclerotic effects. 相似文献
10.
Schiff Leonard J. Moore Steven J. 《In vitro cellular & developmental biology. Plant》1985,21(12):688-692
Summary The ability of cyclic AMP-elevating agents to induce normal differentiation has been investigated in retinoid-deficient hamster
tracheal epithelium in organ culture. Dibutyryl cAMP (dbcAMP) and other cAMP-regulating agents alone caused disappearance
of keratin and regeneration of normal mucociliary epithelium in retinoid-deficient cultures. Incubation of retinoid-deficient
cultures with dbcAMP, isoproterenol, and cholera toxin (CT) (without addition of exogenous retinoid) reversed keratinization
in a dose-dependent manner. The ED50 of cultures treated with dbcAMP was 4×10−6
M; ED50 of isoproterenol was 7×10−5
M; and CT, 0.6 μg/ml. Phosphodiesterase inhibitors and other cAMP analogs were inactive. Dibutyryl cAMP in combination with
theophylline enhanced normal differentiation. Retinoid-deficient tracheas pretreated for 20 h with 10−9
M all-trans-retinoic acid (RA) responded to 10−6
M dbcAMP by potentiating normal differentiation; this concentration of dbcAMP alone was inactive. Isoproterenol showed a similar
response but to a lesser degree. These cAMP-elevating agents applied in combination with theophylline did not increase activity.
This investigation was supported by National Cancer Institute Contract NO1-CP-31012. 相似文献
11.
Takashi Nakahata Kazuyuki Tokumaru Yoshiteru Ito Naoki Ishii Masaki Setoh Yuji Shimizu Toshiya Harasawa Kazunobu Aoyama Teruki Hamada Masakuni Kori Kazuyoshi Aso 《Bioorganic & medicinal chemistry》2018,26(8):1598-1608
G-protein-coupled receptor 52 (GPR52) is classified as an orphan Gs-coupled G-protein-coupled receptor. GPR52 cancels dopamine D2 receptor signaling and activates dopamine D1/N-methyl-d-aspartate receptors via intracellular cAMP accumulation. Therefore, GPR52 agonists are expected to alleviate symptoms of psychotic disorders. A novel series of 1-(benzothiophen-7-yl)-1H-pyrazole as GPR52 agonists was designed and synthesized based on compound 1b. Compound 1b has been reported by our group as the first orally active GPR52 agonist, but high lipophilicity and poor aqueous solubility still remained as issues for candidate selection. To resolve these issues, replacement of the benzene ring at the 7-positon of compound 1b with heterocylic rings, such as pyrazole and pyridine, was greatly expected to reduce lipophilicity to levels for which calculated logD values were lower than that of compound 1b. While evaluating the pyrazole derivatives, introduction of a methyl substituent at the 3-position of the pyrazole ring led to increased GPR52 agonistic activity. Moreover, additional methyl substituent at the 5-position of the pyrazole and further introduction of hydroxy group to lower logD led to significant improvement of solubility while maintaining the activity. As a result, we identified 3-methyl-5-hydroxymethyl-1H-pyrazole derivative 17 (GPR52 EC50?=?21?nM, Emax?=?103%, logD?=?2.21, Solubility at pH 6.8?=?21?μg/mL) with potent GPR52 agonistic activity and good solubility compared to compound 1b. Furthermore, this compound 17 dose-dependently suppressed methamphetamine-induced hyperlocomotion in mice. 相似文献
12.
13.
Yayoi Tada Akinori Haratake Megumi Tobiishi Hideyo Uchiwa Shinichi Watanabe 《Steroids》2009,74(6):504-73
Extracts of Dioscorea coomposita or Dioscorea villosa are consumed as supplemental health foods at the time of climacteric. The extracts contain large amounts of the plant steroid, diosgenin. Here, we studied the safety and efficacy of diosgenin against skin aging at the time of climacteric. In vitro, diosgenin enhanced DNA synthesis in a human 3D skin equivalent model, and increased bromodeoxyuridine uptake and intracellular cAMP level in adult human keratinocytes. The increase of bromodeoxyuridine uptake by diosgenin was blocked by an adenylate cyclase inhibitor, but not by antisense oligonucleotides against estrogen receptor α, estrogen receptor β or an orphan G-protein-coupled receptor, GPR30, indicating the involvement of cAMP but not estrogen receptor α, estrogen receptor β or GPR30. In vivo, administration of diosgenin improved the epidermal thickness in the ovariectomized mice, a climacteric model, without altering the degree of fat accumulation. In order to examine the safety of diosgenin, diosgenin and 17β-estradiol were administered to breast cancer-burdened mice. The results revealed that while 17β-estradiol accelerated the tumor growth, diosgenin did not show this effect. Our finding, a restoration of keratinocyte proliferation in aged skin, suggests that diosgenin may have potential as a safe health food for climacteric. 相似文献
14.
Toshitake Kobayashi Satoshi Sasaki Naoki Tomita Seiji Fukui Noritaka Kuroda Masaharu Nakayama Atsushi Kiba Yoshihiro Takatsu Tetsuya Ohtaki Fumio Itoh Atsuo Baba 《Bioorganic & medicinal chemistry》2010,18(11):3841-3859
GPR54 is a G protein-coupled receptor (GPCR) which was formerly an orphan receptor. Recent functional study of GPR54 revealed that the receptor has an essential role to modulate sex-hormones including GnRH. Though antagonists of GPR54 are expected to be novel drugs for sex-hormone dependent diseases such as prostate cancer or endometriosis, small molecule GPR54 antagonists have not been reported. We have synthesized a series of 2-acylamino-4,6-diphenylpyridines to identify potent GPR54 antagonists. Detailed structure–activity relationship studies led to compound 9l with an IC50 value of 3.7 nM in a GPR54 binding assay, and apparent antagonistic activity in a cellular functional assay. 相似文献
15.
Blad CC von Frijtag Drabbe Künzel JK de Vries H Mulder-Krieger T Bar-Yehuda S Fishman P Ijzerman AP 《Purinergic signalling》2011,7(4):453-462
We tested a panel of naturally occurring nucleosides for their affinity towards adenosine receptors. Both N
6-(2-isopentenyl)adenosine (IPA) and racemic zeatin riboside were shown to be selective human adenosine A3 receptor (hA3R) ligands with affinities in the high nanomolar range (K
i values of 159 and 649 nM, respectively). These values were comparable to the observed K
i value of adenosine on hA3R, which was 847 nM in the same radioligand binding assay. IPA also bound with micromolar affinity to the rat A3R. In a functional assay in Chinese hamster ovary cells transfected with hA3R, IPA and zeatin riboside inhibited forskolin-induced cAMP formation at micromolar potencies. The effect of IPA could be
blocked by the A3R antagonist VUF5574. Both IPA and reference A3R agonist 2-chloro-N
6-(3-iodobenzyl)adenosine-5′-N-methylcarboxamide (Cl-IB-MECA) have known antitumor effects. We demonstrated strong and highly similar antiproliferative
effects of IPA and Cl-IB-MECA on human and rat tumor cell lines LNCaP and N1S1. Importantly, the antiproliferative effect
of low concentrations of IPA on LNCaP cells could be fully blocked by the selective A3R antagonist MRS1523. At higher concentrations, IPA appeared to inhibit cell growth by an A3R-independent mechanism, as was previously reported for other A3R agonists. We used HPLC to investigate the presence of endogenous IPA in rat muscle tissue, but we could not detect the compound.
In conclusion, the antiproliferative effects of the naturally occurring nucleoside IPA are at least in part mediated by the
A3R. 相似文献
16.
Temporini C Ceruti S Calleri E Ferrario S Moaddel R Abbracchio MP Massolini G 《Analytical biochemistry》2009,384(1):123-925
A liquid chromatographic stationary phase containing immobilized membranes from cells expressing the P2Y-like receptor GPR17 is described. Cellular membranes from 1321N1 cells transiently transfected with GPR17 vector [GPR17(+)] and from the same cell line transfected with the corresponding empty vector [GPR17(−)] were entrapped on immobilized artificial membrane (IAM) support and packed into 6.6-mm-i.d. glass columns to create GPR17(+)-IAM and GPR17(−)-IAM stationary phases. Frontal chromatography experiments on both GPR17(+)-IAM and GPR17(−)-IAM demonstrated the presence of a specific interaction with GPR17 only in the former that was maximized by increasing the membrane/IAM ratio. GPR17(+)-IAM was used in frontal affinity chromatography experiments to calculate the dissociation constants (Kd) of three ligands—the antagonist cangrelor (formerly AR-C69931MX, a P2Y12/P2Y13 antagonist), MRS2179 (a P2Y1 receptor antagonist), and the agonist UDP—all of which have been reported to also interact with GPR17. Immobilized GPR17 retained its ability to specifically bind the three analytes, as demonstrated by the agreement of the calculated Kd values with previously reported data. Preliminary ranking experiments suggest the application of GPR17(+)-IAM in ranking affinity studies for the selection of new potential candidates. 相似文献
17.
Chris S. Breivogel John M. McPartland Bhavita Parekh 《Journal of receptor and signal transduction research》2013,33(4):316-326
AbstractPurpose: Previous studies have found non-CB1 non-CB2 G-protein-coupled receptors in rodents that are activated by the aminoalkylindole cannabinoid agonist WIN55212-2. This work obtained evidence for the presence or absence of similar receptors in the brains of other mammals, birds and amphibians.Materials and methods: Antagonism of the stimulation of [35S]GTPγS binding by WIN55212-2 and CP55940 was assessed in multiple CNS regions of rat and canine, and in whole brain membranes from shrew, pigeon, frog and newt. A bioinformatics approach searched for orthologs of GRP3, GPR6, and GPR12 (closely related to cannabinoid receptors) in the genomes of these or related species. Orthologs were examined for amino acid motifs known to impart functionality to receptors.Results: In mammals and pigeon, but not amphibians, a significant fraction of the stimulation of [35S]GTPγS binding by WIN55212-2 was not blocked by the CB1 antagonist SR141716A. BLAST searches found that GPR3 was restricted to mammals. GPR12 orthologs existed in all species, and they shared identical amino acid motifs. GPR6 orthologs existed all species, but with significant departures in the identity of some critical amino acids in bird, more so in amphibian.Conclusions: The portion of WIN55212-2-stimulated [35S]GTPγS binding that was antagonized by SR141716A was consistent with stimulation via CB1 receptors, indicating that antagonist-insensitive activity was via a different G-protein coupled receptor. Pharmacological evidence of this receptor was found in the brains of mammals and pigeon, but not frog or newt. Bioinfomatics results implicate GPR6 as a possible candidate for the additional WIN55212-2-sensitive receptor. 相似文献
18.
Jerry M. Gonzales 《Journal of neurochemistry》1995,64(6):2559-2566
Abstract: Cyclic AMP (cAMP) regulates many important physiological processes. Barbiturates influence cAMP regulation, possibly through effects on G proteins. This study used intact S49 mouse lymphoma cells to characterize the role of G proteins in the effect of barbiturates on cAMP regulation. cAMP accumulation was determined in intact S49 WT (wild-type) and S49 cyc? cells (the Gsα-deficient mutant) by measuring the conversion of [3H]-ATP to [3H]cAMP in cells preloaded with [3H]adenine. Pentobarbital enhanced cAMP accumulation in WT cells in the absence (basal) or presence of isoproterenol but had no effect on the EC50 for isoproterenol. This effect was dose dependent with a 50–60% enhancement at 2 mM pentobarbital. Pentobarbital did not affect forskolin-stimulated cAMP accumulation in WT cells. In cyc? cells, basal and forskolin-stimulated cAMP accumulation were stimulated only at the highest concentration of pentobarbital used (2 mM). Pentobarbital did not affect the inhibition of cAMP accumulation by somatostatin in WT cells, and pertussis toxin treatment of WT cells did not affect the action of pentobarbital on cAMP accumulation. Pentobarbital did not affect isoproterenol-stimulated adenylyl cyclase activity in whole-cell homogenates or membranes prepared from WT cells. The S-(?)-isomer of pentobarbital enhanced isoproterenol-stimulated cAMP accumulation more than the R-(+)-isomer. Phenobarbital and barbituric acid did not enhance isoproterenol-stimulated cAMP accumulation, whereas the anesthetic barbiturates hexobarbital, pentobarbital, and thiopental all enhanced activity. These results suggest that pentobarbital enhances cAMP accumulation in intact WT cells by a mechanism that is dependent on Gsα but independent of Gi. The properties of barbiturates that are responsible for the enhancement of cAMP accumulation may be related to the properties that are responsible for producing sedation and anesthesia. 相似文献
19.
Ornella de Bari Tony Y. Wang Min Liu Piero Portincasa David Q-H. Wang 《Journal of lipid research》2015,56(9):1691-1700
To distinguish the lithogenic effect of the classical estrogen receptor α (ERα) from that of the G protein-coupled receptor 30 (GPR30), a new estrogen receptor, on estrogen-induced gallstones, we investigated the entire spectrum of cholesterol crystallization pathways and sequences during the early stage of gallstone formation in gallbladder bile of ovariectomized female wild-type, GPR30(−/−), ERα(−/−), and GPR30(−/−)/ERα(−/−) mice treated with 17β-estradiol (E2) at 6 µg/day and fed a lithogenic diet for 12 days. E2 disrupted biliary cholesterol and bile salt metabolism through ERα and GPR30, leading to supersaturated bile and predisposing to the precipitation of cholesterol monohydrate crystals. In GPR30(−/−) mice, arc-like and tubular crystals formed first, followed by classical parallelogram-shaped cholesterol monohydrate crystals. In ERα(−/−) mice, precipitation of lamellar liquid crystals, typified by birefringent multilamellar vesicles, appeared earlier than cholesterol monohydrate crystals. Both crystallization pathways were accelerated in wild-type mice with the activation of GPR30 and ERα by E2. However, cholesterol crystallization was drastically retarded in GPR30(−/−)/ERα(−/−) mice. We concluded that E2 activates GPR30 and ERα to produce liquid crystalline versus anhydrous crystalline metastable intermediates evolving to cholesterol monohydrate crystals from supersaturated bile. GPR30 produces a synergistic lithogenic action with ERα to enhance E2-induced gallstone formation. 相似文献
20.
Kyungsu Kang Saet Byoul Lee Sang Hoon Jung Kwang Hyun Cha Woo Dong Park Young Chang Sohn Chu Won Nho 《Molecules and cells》2009,27(3):351-357
Phytoestrogens are the natural compounds isolated from plants, which are structurally similar to animal estrogen, 17β-estradiol.
Tectoridin, a major isoflavone isolated from the rhizome of Belamcanda chinensis. Tectoridin is known as a phytoestrogen, however, the molecular mechanisms underlying its estrogenic effect are remained
unclear. In this study we investigated the estrogenic signaling triggered by tectoridin as compared to a famous phytoestrogen,
genistein in MCF-7 human breast cancer cells. Tectoridin scarcely binds to ER α as compared to 17β-estradiol and genistein.
Despite poor binding to ER α, tectoridin induced potent estrogenic effects, namely recovery of the population of cells in
the S-phase after serum starvation, transactivation of the estrogen response element, and induction of MCF-7 cell proliferation.
The tectoridin-induced estrogenic effect was severely abrogated by treatment with U0126, a specific MEK1/2 inhibitor. Tectoridin
promoted phosphorylation of ERK1/2, but did not affect phosphorylation of ER α at Ser118. It also increased cellular accumulation of cAMP, a hallmark of GPR30-mediated estrogen signaling. These data imply that
tectoridin exerts its estrogenic effect mainly via the GPR30 and ERK-mediated rapid nongenomic estrogen signaling pathway.
This property of tectoridin sets it aside from genistein where it exerts the estrogenic effects via both an ER-dependent genomic
pathway and a GPR30-dependent nongenomic pathway. 相似文献