A large number of β-adrenergic receptor (β-AR) agonists and antagonists are widely used in the treatment of cardiovascular diseases and other diseases. Nonetheless, it remains unclear whether these commonly used β-AR drugs can activate downstream β- arrestin-biased signaling pathways. The objective of this study was to investigate β-arrestin2 recruitment effects of β-AR agonists and antagonists that were commonly used in clinical practice. We used TANGO (transcriptional activation following arrestin translocation) assay to detect the β-arrestin2 recruitment by β-AR ligands in HEK293 cell line (HTLA cells) stably transfected with tetracycline transactivator protein (tTA) dependent luciferase reporter and β-arrestin2-TEV fusion gene. Upon activation of β-AR by a β-AR ligand, β-arrestin2 was recruited to the C terminus of the receptor, followed by cleavage of the G protein-coupled receptors (GPCRs) fusion protein at the TEV protease-cleavage site. The cleavage resulted in the release of tTA, which, after being transported to the nucleus, activated transcription of the luciferase reporter gene. The results showed that β-AR non-selective agonists epinephrine, noradrenaline and isoprenaline all promoted β-arrestin2 recruitment at β1-AR and β2-AR. β1-AR selective agonists dobutamine and denopamine both promoted β-arrestin2 recruitment at β1-AR. β2-AR selective agonists procaterol and salbutamol promoted β-arrestin2 recruitment at β2-AR. β-AR non-selective antagonists alprenolol and pindolol promoted β-arrestin2 recruitment at β1-AR. β1-AR selective antagonists celiprolol and bevantolol showed β-arrestin2 recruitment at β1-AR. β2-AR selective antagonists butoxamine showed β-arrestin2 recruitment at β1-AR. These results provide some clues for the potential action of β-AR drugs, and lay a foundation for the screening of β-arrestin-biased β-AR ligands.
Humans ; beta-Arrestin 2/metabolism* ; HEK293 Cells ; Adrenergic beta-Agonists/pharmacology* ; Isoproterenol/pharmacology* ; Receptors, Adrenergic, beta-2/metabolism* ; Norepinephrine/pharmacology*

OBJECTIVETo investigate the alteration of expressions of beta(1)-, beta(2)-, beta(3)-adrenoceptor mRNA in human myocardial tissue and the relation between their expressions and cardiac function in patient with heart failure.

METHODSThe mRNA expressions of beta(1)-, beta(2)- and beta(3)-adrenergic receptors in myocardial tissue were analyzed by using the reverse transcriptase-polymerase chain reaction in 24 patients with heart failure of valvular heart disease and 5 control subjects.

RESULTSBeta(1)-adrenergic receptor mRNA expressions in myocardium were significantly lower in patients with heart failure than those in control subjects, and progressively reduced with aggravation of heart function. By contrast, beta(3)-adrenoceptor mRNA expressions were significantly higher in patients with heart failure than those in controls, and progressively elevated with aggravation of cardiac function. No difference was observed in beta(2)-adrenergic receptor among all groups.

CONCLUSIONThe changes of beta-adrenergic receptor mRNA expression are associated with the severity of heart failure.

Adult ; Case-Control Studies ; Female ; Heart Failure ; genetics ; metabolism ; physiopathology ; Humans ; Male ; Middle Aged ; RNA, Messenger ; metabolism ; Receptors, Adrenergic, beta-1 ; genetics ; metabolism ; Receptors, Adrenergic, beta-2 ; genetics ; metabolism ; Receptors, Adrenergic, beta-3 ; genetics ; metabolism

In the heart, stimulation of beta-adrenergic receptors (betaAR) serves as the most powerful means to increase cardiac contractility and relaxation in response to stress or a "fight-or-flight" situation. However, sustained beta-adrenergic stimulation promotes pathological cardiac remodeling such as myocyte hypertrophy, apoptosis and necrosis, thus contributing to the pathogenesis of chronic heart failure. Over the past decade, compelling evidence has demonstrated that coexisting cardiac betaAR subtypes, mainly beta(1)AR and beta (2)AR, activate markedly different signaling cascades. As a result, acute beta(1)AR stimulation activates the G(s) -adenylyl cyclase-cAMP-PKA signaling that can broadcast throughout the cell, whereas beta(2)AR-evoked cAMP signaling is spatially and functionally compartmentalized, due to concurrent G(i) activation. Chronic stimulation of beta(1)AR and beta(2)AR elicits opposing effects on the fate of cardiomyocytes: beta(1)AR induces hypertrophy and apoptosis; but beta(2)AR promotes cell survival. The cardiac protective effect of beta(2)AR is mediated by a signaling pathway sequentially involving G(i), G(betagamma), PI3K and Akt. Unexpectedly, beta(1)AR-induced myocyte hypertrophy and apoptosis are independent of the classic cAMP/PKA pathway, but require activation of Ca(2+)/calmodulin-dependent kinase II (CaMK II). The outcomes of cardiac-specific transgenic overexpression of either beta AR subtype in mice have reinforced the fundamentally different functional roles of these betaAR subtypes in governing cardiac remodeling and performance. These new insights regarding betaAR subtype stimulation not only provide clues as to cellular and molecular mechanisms underlying the beneficial effects of beta AR blockers in patients with chronic heart failure, but also delineate rationale for combining selective beta(1)AR blockade with moderate beta(2)AR activation as a potential novel therapy for the treatment of chronic heart failure.
Adenylyl Cyclases ; metabolism ; Animals ; Cyclic AMP-Dependent Protein Kinases ; metabolism ; GTP-Binding Proteins ; metabolism ; Heart ; physiology ; Heart Failure ; physiopathology ; Humans ; Myocardium ; metabolism ; Receptors, Adrenergic, beta ; classification ; physiology ; Receptors, Adrenergic, beta-1 ; physiology ; Receptors, Adrenergic, beta-2 ; physiology ; Signal Transduction

OBJECTIVETo investigate the significance of beta-adrenergic receptor 2 (beta2-AR) and vascular endothelial growth factor-2 (VEGFR-2) in the occurrence and development of infantile hemangioma through detecting the expression of beta2-AR and VEGFR-2 in the different stages of infantile hemangiomas.

METHODSAccording to the Mulliken's classification standard, we classified the specimens as proliferating group (32 cases), involuting group (17 cases) and involuted group (11 cases). Normal skin tissue surrounding the hemangioma from 7 cases were chosen as control group. The expression of beta2-AR and VEGFR-2 was detected by immunohistochemical technique in proliferating hemangioma, involuting hemangioma, involuted hemangioma. The mean optical density was measured by image analysis system (Image Pro Plus 6.0) and SPSS 16.0 software was applied for statistical analysis.

RESULTSThe expression of beta2-AR and VEGFR-2 was strongly positive in proliferating hemangioma, while positive in involuting hemangioma and weakly positive in the involuted stage. The mean optical density of each phase was 0.064 751 2 +/- 0.012 747, 0.031 6017 +/- 0.006 848,0.011 869 8 +/- 0.039 349 for beta2-AR, and 0.068 940 9 +/- 0.029 274, 0.028 445 5 +/- 0.006 396, 0.011 184 1 +/- 0.004 198 for VEGFR-2. The differences between different stages had a statistically significance (P < 0.05). Correlation analysis on the mean optical density between beta2-AR and VEGFR-2 had a statistically significance (P < 0. 05).

CONCLUSIONSBeta2-AR and VEGFR-2 may be involved in the occurrence and development of infantile hemangioma.

Child ; Child, Preschool ; Female ; Hemangioma ; metabolism ; Humans ; Infant ; Male ; Receptors, Adrenergic, beta-2 ; metabolism ; Receptors, Vascular Endothelial Growth Factor ; metabolism

OBJECTIVETo elucidate the relationship between rat hepatic stellate cells (HSC) and sympathetic neurotransmitter norepinephrine (NE) during liver fibrosis.

METHODSUsing immunofluorescence and RT-PCR, the expressions of a1 and b2-adrenoceptors in activated HSC were detected. Methyl thiazolyl tetrazolium (MTT) was adopted to investigate the effect of NE on the proliferation of HSC. Meanwhile, the expressions of collagen-1, transforming growth factor beta (TGFb) and smooth muscle a-actin (a-SMA) in NE-stimulated HSC were detected by RT-PCR. The contents of NE in HSC were determined by high performance liquid chromatography-electrochemical detector (HPLC-ECD).

RESULTSThe a1 and b2-adrenoceptors were expressed in HSC. NE markedly stimulated the proliferation of HSC in a concentration-dependent manner (F = 140.464, P less than 0.05). NE induced the mRNA expressions of collagen-1, TGFb and a-SMA in HSC (t= -4.160; t= -8.763; t= -17.651, P less than 0.05). HSC were synthesizing and releasing NE, especially when stimulated with platelet-derived growth factor (PDGF) (10 ng/ml) (t= -32.907, P less than 0.05).

CONCLUSIONOur findings show that HSC are direct targets of NE and HSC are hepatic neuroglial cells that produce and respond to sympathetic neurotransmitter norepinephrine, suggesting that interrupting sympathetic nervous system signaling may be useful in the treatment of liver fibrosis.

Actins ; metabolism ; Animals ; Cell Proliferation ; drug effects ; Cells, Cultured ; Collagen Type I ; metabolism ; Hepatic Stellate Cells ; drug effects ; metabolism ; Liver Cirrhosis ; Norepinephrine ; pharmacology ; Rats ; Receptors, Adrenergic, alpha-1 ; metabolism ; Receptors, Adrenergic, beta-2 ; metabolism ; Transforming Growth Factor beta ; metabolism

Alleles ; General Surgery ; methods ; Genetic Variation ; Humans ; Hypotension ; drug therapy ; Receptors, Adrenergic, beta-2 ; genetics ; metabolism ; Vasoconstrictor Agents ; administration & dosage

AIMTo investigate the role of overexpression of beta2-adrenoceptor on contraction in cardiac myocytes isolated from failure hearts of rats and primarily analyses its mechanisms.

METHODSPrimarily cultured cardiac myocytes were infected with adenovirus containing the sequence for human beta2-adrenoceptors. The expression of beta2-adrenoceptors was tested by Western blot. The contraction amplitudes induced by isoprenaline stimulation were measured.

RESULTSOverexpression of beta2-adrenoceptor increased the content in failure cardiac myocytes. The contraction amplitudes in failure cardiac myocytes were lower than that in the control (P < 0.01). Overexpression of beta2 adrenoceptor improved the contraction of failure cardiac myocytes (P < 0.01, Failure+ Adv.Beta2 group vs. Failure group). Selective beta2-adrenoceptor antagonist ICI 118,551 partially reversed the effects (P < 0.05, Failure+ Adv.beta2 + ICI group vs Failure + Adv.beta2 group), but the contraction amplitudes in this Failure +/- Adv.beta2 + ICI 118,551 group were still higher than that in only heart failure group (P < 0.05). Selective beta1 adrenoceptor antagonist CGP20712A completely inhibited the effects of overexpression of beta2 adrenoceptor on contraction amplitude in failure cardiac myocytes.

CONCLUSIONOverexpression of beta2-adrenoceptors improves the contraction of cardiac myocytes isolated from failure hearts of rats. The effect is related to beta1-adrenoceptor.

Adenoviridae ; genetics ; Adrenergic beta-Antagonists ; pharmacology ; Animals ; Cells, Cultured ; Heart Failure ; metabolism ; physiopathology ; Humans ; Imidazoles ; pharmacology ; Isoproterenol ; pharmacology ; Male ; Myocardial Contraction ; Myocytes, Cardiac ; metabolism ; Rats ; Rats, Sprague-Dawley ; Receptors, Adrenergic, beta-2 ; genetics ; metabolism

OBJECTIVE: Catecholamine play a central role in the regulation of energy expenditure, in part by stimulating lipid mobilization through lipolysis in fat cells. The beta-2 adrenergic receptor(BAR-2) is a major lipolytic receptor in human fat cells. A recent study has shown that common polymorphisms occuring at codon 16 and 27 of the BAR-2 gene are significantly associated with obesity and lypolytic BAR-2 function in adipose tissue. We investigated whether the previously described human BAR-2 gene polymorphisms are associated with obesiy and NIDDM in Koreans. METHODS: All subjests were divided into two groups, non-obese and obese group, according to their body mass index. And their clinical characteristics were evaluated. The BAR-2 gene polymorphisms were analyzed by PCR-RFLP in 89 nondiabetics and 106 patients with NIDDM. RESULTS: When the allele frequency of BAR-2 gene polymorphisms was compared with that of western people, there was a significant difference. In our study, there was no significant difference in the allele frequency of BAR-2 gene polymorphisms at codons 16 and 27 between nonobese and obese group both nondiabetics and NIDDM subjects. The frequency of Glu27 homozygotes was very rare(1.1%). Body mass index(BMI), waist-hip ratio(WHR), and serum glucose and insulin secretion of the nondiabetics with polymorphism of codon 16 or codon 27 did not differ from those of the subjects without the polymorphisms. In NIDDM group, the Gly16 homozygotes had a lower BMI than Arg16 homozygotes without any difference in WHR and the other laboratory parameters. Neither clinical or laboratory parameters of the diabetics with the polymorphism at codon 27 differ from those of subjectes without the polymorphism. CONCLUSION: These findings suggest that the genetic variability in the human BAR-2 gene is not a major determinant for the development of obesity and NIDDM in Koreans.
Adipocytes ; Adipose Tissue ; Blood Glucose ; Body Mass Index ; Codon ; Diabetes Mellitus, Type 2 ; Energy Metabolism ; Gene Frequency ; Homozygote ; Humans ; Insulin ; Lipid Mobilization ; Lipolysis ; Obesity* ; Receptors, Adrenergic, beta-2*

Animals ; Cell Survival ; Cells, Cultured ; GTP-Binding Proteins ; metabolism ; Isoproterenol ; adverse effects ; Myocytes, Cardiac ; cytology ; drug effects ; metabolism ; Rats ; Rats, Sprague-Dawley ; Receptors, Adrenergic, beta-2 ; metabolism

The expression of beta-adrenergic receptor subtypes and its effect on neonatal rat cardiac fibroblast proliferation were investigated by radioligand binding assay and [(3)H]-thymidine incorporation analysis, respectively. The results indicated that there was no significant difference in the beta-adrenergic receptor density (B(max)) and affinity (K(D)) between cardiomyocytes and cardiac fibroblasts. The [(125)I]-pindolol competitive inhibition curves (ICI 118551 and CGP 20712A) were significantly better fit in a one-site model in membrane preparation of cardiac fibroblasts. In cultured cardiac fibroblasts, 0.1 micromol/L isoproterenol-induced [(3)H]-thymidine incorporation was completely inhibited by a selective beta (2)-AR antagonist ICI 118551, or a non-selective beta-AR antagonist propranolol, but not by CGP 20712A, a selective beta(1)-AR antagonist. These results suggest that isoproterenol-induced cardiac fibroblast proliferation is mediated by beta(2)-AR, the preponderant beta-AR subtype in cardiac fibroblasts.
Animals ; Animals, Newborn ; Cell Proliferation ; Cells, Cultured ; Fibroblasts ; cytology ; metabolism ; Myocytes, Cardiac ; cytology ; metabolism ; Rats ; Rats, Wistar ; Receptors, Adrenergic, beta-2 ; genetics ; metabolism ; physiology