Molecular cloning of a gene encoding the histamine H2 receptor.
Ontology highlight
ABSTRACT:
SUBMITTER: Gantz I
PROVIDER: S-EPMC50824 | biostudies-other | 1991 Jan
REPOSITORIES: biostudies-other
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Project description:With the world threatened by a second surge in the number of Coronavirus cases, there is an urgent need for the development of effective treatment for the novel coronavirus (COVID-19). Recently, global attention has turned to preliminary reports on the promising anti-COVID-19 effect of histamine H2-receptor antagonists (H2RAs), most especially Famotidine. Therefore, this study was designed to exploit a possible molecular basis for the efficacy of H2RAs against coronavirus. Molecular docking was performed between four H2RAs, Cimetidine, Famotidine, Nizatidine, Ranitidine, and three non-structural proteins viz. NSP3, NSP7/8 complex, and NSP9. Thereafter, a 100 ns molecular dynamics simulation was carried out with the most outstanding ligands to determine the stability. Thereafter, Famotidine and Cimetidine were subjected to gene target prediction analysis using HitPickV2 and eXpression2Kinases server to determine the possible network of genes associated with their anti-COVID activities. Results obtained from molecular docking showed the superiority of Famotidine and Cimetidine compared to other H2RAs with a higher binding affinity to all selected targets. Molecular dynamic simulation and MMPBSA results revealed that Famotidine as well as Cimetidine bind to non-structural proteins more efficiently with high stability over 100 ns. Results obtained suggest that Famotidine and Cimetidine could be a viable option to treat COVID-19 with a mechanism of action that involves the inhibition of viral replication through the inhibition of non-structural proteins. Therefore, Famotidineand Cimetidine qualify for further study as a potential treatment for COVID-19.
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Project description:The histamine H2 receptor (H2R) plays an important role in the regulation of gastric acid secretion. Therefore, it is a main drug target for the treatment of gastroesophageal reflux or peptic ulcer disease. However, there is as of yet no 3D-structural information available hampering a mechanistic understanding of H2R. Therefore, we created a model of the histamine-H2R-Gs complex based on the structure of the ternary complex of the β2-adrenoceptor and investigated the conformational stability of this active GPCR conformation. Since the physiologically relevant motions with respect to ligand binding and conformational changes of GPCRs can only partly be assessed on the timescale of conventional MD (cMD) simulations, we also applied metadynamics and Gaussian accelerated molecular dynamics (GaMD) simulations. A multiple walker metadynamics simulation in combination with cMD was applied for the determination of the histamine binding mode. The preferential binding pose detected is in good agreement with previous data from site directed mutagenesis and provides a basis for rational ligand design. Inspection of the H2R-Gs interface reveals a network of polar interactions that may contribute to H2R coupling selectivity. The cMD and GaMD simulations demonstrate that the active conformation is retained on a μs-timescale in the ternary histamine-H2R-Gs complex and in a truncated complex that contains only Gs helix α5 instead of the entire G protein. In contrast, histamine alone is unable to stabilize the active conformation, which is in line with previous studies of other GPCRs.
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Project description:A functional cDNA clone for the histamine H1 receptor was isolated from a cDNA library of bovine adrenal medulla by a combination of molecular cloning in an expression vector and electrophysiological assay in Xenopus oocytes. The H1 receptor cDNA encodes a protein of 491 amino acids (Mr 55,954) with seven putative transmembrane domains, illustrating the similarity to other receptors that couple with guanine nucleotide-binding regulatory proteins (G protein-coupled receptors). The sequence homology between the H1 and H2 receptors is not higher than that between the histamine H1 and m1-muscarinic receptors. The cloned receptor protein expressed in COS-7 cells bound specifically to [3H]mepyramine, an H1 receptor antagonist, and this binding was displaced by H1 receptor antagonists and histamine with affinities comparable with those in membranes of bovine adrenal medulla. H1 receptor mRNA was shown to be expressed in brain and in peripheral tissues, including lung, small intestine, and adrenal medulla. This investigation discloses the molecular nature of the H1 receptor--a receptor that mediates diverse neuronal and peripheral actions of histamine and that may be of therapeutic importance in allergy.
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Project description:Histamine H2 receptor (HRH2) was previously suggested to affect the proliferation of breast cancer cells and disease-free survival of breast cancer patients. Furthermore, a common polymorphism, rs2067474, was identified in an enhancer element of the HRH2 gene promoter and was reported to be associated with various diseases including cancer. However, the relationship between this polymorphism and breast cancer risk and malignant degree remains unclear. The aim of this study was to clarify the clinical association of rs2067474 polymorphism with breast cancer. A total of 201 unrelated Chinese Han breast cancer patients and 238 ethnicity-matched health controls were recruited and rs2067474 polymorphism was genotyped. Logistic regression analyses were performed to calculate the odds ratios (ORs) as a measure of association of genotype with breast cancer according to 3 genetic models (dominant, recessive, and additive). Although the percentage of hormone receptor negative cases tended to be higher in AA genotypes, we did not find any significant associations of rs2067474 polymorphism with breast cancer risk or with related clinicopathological parameters in the present study, which indicates that rs2067474 polymorphism of HRH2 gene might not be a risk factor in the development of breast cancer in Chinese Han population.
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Project description:Dysbiosis, an imbalance of intestinal flora, can cause serious conditions such as obesity, cancer, and psychoneurological disorders. One cause of dysbiosis is inflammation. Ulcerative enteritis is a side effect of non-steroidal anti-inflammatory drugs (NSAIDs). To counteract this side effect, we proposed the concurrent use of histamine H2 receptor antagonists (H2RA), and we examined the effect on the intestinal flora. We generated a murine model of NSAID-induced intestinal mucosal injury, and we administered oral H2RA to the mice. We collected stool samples, compared the composition of intestinal flora using terminal restriction fragment length polymorphism, and performed organic acid analysis using high-performance liquid chromatography. The intestinal flora analysis revealed that NSAID [indomethacin (IDM)] administration increased Erysipelotrichaceae and decreased Clostridiales but that both had improved with the concurrent administration of H2RA. Fecal levels of acetic, propionic, and n-butyric acids increased with IDM administration and decreased with the concurrent administration of H2RA. Although in NSAID-induced gastroenteritis the proportion of intestinal microorganisms changes, leading to the deterioration of the intestinal environment, concurrent administration of H2RA can normalize the intestinal flora.
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Project description:Background:Ficus religiosa L. is generally known as Peepal and belongs to family Moraceae. The tree is a source of many compounds having high medicinal value. In gastrointestinal tract, histamine H2 receptors have key role in histamine-stimulated gastric acid secretion. Their over stimulation causes its excessive production which is responsible for gastric ulcer. Objective:This study aims to screen the range of phytochemicals present in F. religiosa for binding with human histamine H2 and identify therapeutics for a gastric ulcer from the plant. Materials and Methods:In this work, a 3D-structure of human histamine H2 receptor was modeled by using homology modeling and the predicted model was validated using PROCHECK. Docking studies were also performed to assess binding affinities between modeled receptor and 34 compounds. Molecular dynamics simulations were done to identify most stable receptor-ligand complexes. Absorption, distribution, metabolism, excretion, and screening was done to evaluate pharmacokinetic properties of compounds. Results:The results suggest that seven ligands, namely, germacrene, bergaptol, lanosterol, Ergost-5-en-3beta-ol, ?-amyrin acetate, bergapten, and ?-cadinene showed better binding affinities. Conclusion:Among seven phytochemicals, lanosterol and ?-amyrin acetate were found to have greater stability during simulation studies. These two compounds may be a suitable therapeutic agent against histamine H2 receptor. SUMMARY:This study was performed to screen antiulcer compounds from F. religiosa. Molecular modeling, molecular docking and MD simulation studies were performed with selected phytochemicals from F. religiosa. The analysis suggests that Lanosterol and ?-amyrin may be a suitable therapeutic agent against histamine H2 receptor. This study facilitates initiation of the herbal drug discovery process for the antiulcer activity. Abbreviations used: ADMET: Absorption, distribution, metabolism, excretion and toxicity, DOPE: Discrete Optimized Potential Energy, OPLS: Optimized potential for liquid simulations, RMSD: Root-mean-square deviation, HOA: Human oral absorption, MW: Molecular weight, SP: Standard-precision, XP: Extra-precision, GPCRs: G protein-coupled receptors, SASA: Solvent accessible surface area, Rg: Radius of gyration, NHB: Number of hydrogen bond.
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Project description:Restless legs syndrome (RLS) is a common sensorimotor disorder, which can disrupt sleep and is thought to be caused in part by low cellular iron stores. Proton pump inhibitors (PPI) and histamine H2-receptor antagonists (H2A) are among the most commonly used drugs worldwide and show evidence of causing iron deficiency. We conducted a case/non-case observational study of blood donors in the United States (N = 13,403; REDS-III) and Denmark (N = 50,323; Danish Blood Donor Study, DBDS), both of which had complete blood count measures and a completed RLS assessment via the Cambridge-Hopkins RLS questionnaire. After adjusting for age, sex, race, BMI, blood donation frequency, smoking, hormone use, and iron supplement use, PPI/H2A use was associated with RLS (odds ratio [OR] = 1.41; 95% confidence interval [CI], 1.13-1.76; p = 0.002) in REDS-III for both PPI (OR = 1.43; CI, 1.03-1.95; p = 0.03) and H2A (OR = 1.56; CI, 1.10-2.16; p = 0.01). DBDS exhibited a similar association with PPIs/H2As (OR = 1.29; CI, 1.20-1.40; p < 0.001), and for PPIs alone (OR = 1.27; CI, 1.17-1.38; p < 0.001), but not H2As alone (OR = 1.18; CI, 0.92-1.53; p = 0.2). We found no evidence of blood iron stores mediating this association. The association of PPI, and possibly H2A, consumption with RLS independent of blood iron status and other factors which contribute to RLS risk suggest the need to re-evaluate use of PPI/H2A in populations at particular risk for RLS.
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Project description:BackgroundMyocardial H2 receptor activation may promote cardiac fibrosis and apoptosis in pre-clinical models and histamine H2 receptor antagonist (H2RA) use may improve symptoms in participants with heart failure (HF); however, relationships between H2RA use, incident HF, and longitudinal change in left ventricular (LV) morphology are not known.ObjectivesThis study sought to determine whether H2RA use is associated with incident HF and change in LV morphology over time.MethodsWe included 6,378 men and women from MESA (Multi-Ethnic Study of Atherosclerosis), a multicenter prospective observational cohort of participants without cardiovascular disease at baseline. Cox proportional hazards were used to estimate the association between H2RA use and incident HF in adjusted models. In participants with cardiac magnetic resonance imaging, associations between H2RA use, baseline LV morphology (n = 4,691), and longitudinal change in the LV (n = 2,806) were estimated using linear regression.ResultsH2RAs were used by 313 participants but not by the other 6,065 individuals. During a median follow-up of 11.2 years, 236 participants developed HF. In adjusted models, baseline H2RA use relative to nonuse was associated with 62% lower risk for incident HF (p = 0.02). H2RA use was associated with preserved stroke volume, LV end-diastolic volume, and mass/volume ratio as measured by cardiac magnetic resonance imaging over approximately 10 years (all p < 0.05). There were no associations between H2RA use and LV mass or ejection fraction.ConclusionsH2RA use was associated with reduced risk for incident HF. Left heart morphology over time suggests less age-related change in H2RA users. These associations suggest histamine signaling may be important in the pathogenesis of HF. (Multi-Ethnic Study of Atherosclerosis [MESA]; NCT00005487).
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Project description:Ligand affinity has been a fundamental concept in the field of pharmacology and has traditionally been considered to be constant for a given receptor-ligand interaction. Recent studies have demonstrated that this is not true for all three members of the G(s)-coupled beta-adrenoceptor family. This study evaluated antagonist affinity measurements at a different G(s)-coupled receptor, the histamine H(2) receptor, to determine whether antagonist affinity measurements made at a different family of GPCRs were constant.CHO cells stably expressing the human histamine H(2) receptor and a CRE-SPAP reporter were used and antagonist affinity was assessed in short-term cAMP assays and longer term CRE gene transcription assays.Nine agonists and seven antagonists, of sufficient potency at the H(2) receptor to examine in detail, were identified. Measurements of antagonist affinity were the same regardless of the efficacy of the competing agonist, time of agonist incubation, cellular response measured or presence of a PDE inhibitor.Antagonist affinity at the G(s)-coupled histamine H(2) receptor obeys the accepted dogma for antagonism at GPCRs. This study further confirms that something unusual is indeed happening with the beta-adrenoceptors and is not an artefact related to the transfected cell system used. As the human histamine H(2) receptor does not behave in a similar manner to any of the human beta-adrenoceptors, it is clear that information gathered from one GPCR cannot be simply extrapolated to predict the behaviour of another GPCR. Each GPCR therefore requires careful and detailed evaluation on its own.
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Project description:We used a combination of density functional theory (DFT) calculations and the implicit quantization of the acidic N-H and O-H bonds to assess the effect of deuteration on the binding of agonists (2-methylhistamine and 4-methylhistamine) and antagonists (cimetidine and famotidine) to the histamine H2 receptor. The results show that deuteration significantly increases the affinity for 4-methylhistamine and reduces it for 2-methylhistamine, while leaving it unchanged for both antagonists, which is found in excellent agreement with experiments. The revealed trends are interpreted in the light of the altered strength of the hydrogen bonding upon deuteration, known as the Ubbelohde effect, which affects ligand interactions with both active sites residues and solvent molecules preceding the binding, thus providing strong evidence for the relevance of hydrogen bonding for this process. In addition, computations further underline an important role of the Tyr250 residue for the binding. The obtained insight is relevant for the therapy in the context of (per)deuterated drugs that are expected to enter therapeutic practice in the near future, while this approach may contribute towards understanding receptor activation and its discrimination between agonists and antagonists.
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