| 1. |
- Hellgren, I, et al.
(författare)
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Study of the beta1 adrenergic receptor expression in human tissues: immunological approach.
- 2000
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Ingår i: Biological & pharmaceutical bulletin. - : Pharmaceutical Society of Japan. - 0918-6158 .- 1347-5215. ; 23:6, s. 700-3
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Tidskriftsartikel (refereegranskat)abstract
- Questions exist regarding tissue distribution of the beta1 adrenergic receptor (beta1-AR). The aim of this study was to investigate relative distribution patterns of the beta1-AR at the protein level in a variety of human tissues by Western blot analysis. The specificity of anti-peptide antibodies was confirmed both by Western blot with recombinant beta1-AR expressed as a membrane protein in E. coli and by immunoprecipitation of membranes from Sf9 cells infected with baculovirus to express the human recombinant beta1-AR. beta1-AR was found in all tissues examined. The relative amount of protein varied significantly between the tissues, from highest in lung and testis to very low in liver. beta1-ARs were rather abundant in heart, kidney, placenta, spleen and thyroid. These results reveal unique distribution of beta1-AR protein that suggests its tissue specific role. Moreover, our data demonstrate a high sensitivity of immunological detection that allows direct comparison of beta1-AR subtype expression and could be used for receptor study in biopsies available in limited amounts, such as human heart biopsy.
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| 2. |
- Levin, Malin, 1973, et al.
(författare)
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A novel polymorphism in the gene coding for the beta(1)-adrenergic receptor associated with survival in patients with heart failure.
- 2000
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Ingår i: European heart journal. - : Oxford University Press (OUP). - 0195-668X. ; 21:22, s. 1853-8
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: The adrenergic nervous system is of major importance in congestive heart failure. No genetic polymorphism has previously been identified in the beta(1)-adrenergic receptor gene. The aim of this study was to find possible mutations in this gene and to relate such findings to morbidity and prognosis in heart failure. METHODS AND RESULTS: Genomic DNA was extracted from blood leukocytes from patients with congestive heart failure (n=184) and from age-matched controls (n=77). The part of the beta(1)-adrenergic receptor gene corresponding to nucleotide 1-255 was amplified by polymerase chain reaction and analysed by automated sequencing. The patients were investigated by echocardiography and followed regarding symptoms and survival for 5 years. A missense mutation was identified at nucleotide position 145 in the beta(1)-adrenergic receptor gene, which predicted an amino acid substitution at position 49 (Ser49Gly). The allele frequency of the Gly49 variant was 0.13 in controls and 0.18 in patients (P=0.19). At the time of the 5-years follow-up, 62% of the patients with the wild type gene and 39% of the patients with the Ser49Gly variant had died or had experienced hospitalization (P=0.005). Patients without the mutation had significantly poorer survival compared to those with the mutation, risk ratio 2.34 (95% CI 1.30-4.20), P=0.003. In a mulivariate analysis, the risk ratio was 2.03 (95% CI 0.99-4.16) P=0.05. CONCLUSION: A novel missense mution in the beta(1)-adrenergic receptor gene was associated with a decreased mortality risk in patients with congestive heart failure. These data suggest that the beta(1)-receptor Ser49Gly variant might be associated with altered receptor function, resulting in myocardial protection in patients with heart failure.
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| 3. |
- Levin, Malin, 1973, et al.
(författare)
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The myocardium-protective Gly-49 variant of the beta 1-adrenergic receptor exhibits constitutive activity and increased desensitization and down-regulation.
- 2002
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Ingår i: The Journal of biological chemistry. - 0021-9258. ; 277:34, s. 30429-35
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Tidskriftsartikel (refereegranskat)abstract
- The beta(1)-adrenergic receptor (beta(1)AR) is a major mediator of catecholamine effects in human heart. Patients with heart failure who were hetero- or homozygous for the Gly-49 variant of the beta(1)AR (Gly-49-beta(1)AR) showed improved long-term survival as compared with those with the Ser-49 genotype. Here, the functional consequences of this polymorphism were studied in cells expressing either variant. The Gly-49-beta(1)AR demonstrated characteristic features of constitutively active receptors. In cells expressing the Gly-49-beta(1)AR, both basal and agonist-stimulated adenylyl cyclase activities were higher than in cells expressing the Ser-49 variant (Ser-49-beta(1)AR). The Gly-49-beta(1)AR was more sensitive to the inhibitory effect of the inverse agonist metoprolol and displayed increased affinity for agonists. Isoproterenol potency for adenylyl cyclase activation was higher on membranes expressing the Gly-49-beta(1)AR than on those expressing the Ser-49-beta(1)AR. After incubation with saturating concentrations of catecholamines or sustained stimulation, the Gly-49 variant showed a much higher desensitization, which largely prevailed over constitutive activity in terms of cAMP accumulation. The Gly-49-beta(1)AR also displayed a more profound agonist-promoted down-regulation than the Ser-49 variant. The stronger regulation of the Gly-49-beta(1)AR could explain the beneficial effect of the Gly-49 genotypes on survival, further supporting the concept that beta(1)AR desensitization is protective in heart failure.
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| 4. |
- Mobini, Reza, 1965, et al.
(författare)
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A monoclonal antibody directed against an autoimmune epitope on the human beta1-adrenergic receptor recognized in idiopathic dilated cardiomyopathy.
- 2000
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Ingår i: Hybridoma. - : Mary Ann Liebert Inc. - 0272-457X. ; 19:2, s. 135-42
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Tidskriftsartikel (refereegranskat)abstract
- A monoclonal antibody (MAb M16) was obtained by immunizing Balb/C mice with free peptide H26R, corresponding to the second extracellular loop of the human beta1-adrenergic receptor (beta1AR), against which functional autoantibodies have been detected in patients with idiopathic dilated cardiomyopathy. The MAb was found to be of IgG2b type and directed against a conformational epitope, encompassing the sequence recognized by the human autoantibodies. BIAcore measurements yielded an equilibrium constant of 6.5 X 10(7) M1 with an association rate constant (kon) of 6.5 X 10(4) M(-1) sec(-1) and a dissociation rate constant (koff) of 1.0 X 10(-3) sec(-1). It immunoprecipitated only poorly the solubilized beta1AR of Sf9 cell membranes. Functionally, the MAb was capable of not only reducing the number of the maximal binding sites to the beta1-adrenergic receptor of transfected Sf9 cell membranes, but also of displaying a positive chronotropic effect on cultured neonatal rat cardiomyocytes. These properties, which the MAb shares with the human autoantibodies, makes it an interesting tool for passive transfer studies in mice.
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