Quantification of beta adrenergic receptor subtypes in beta-arrestin knockout mouse airways.

Abstract

In allergic asthma Beta 2 adrenergic receptors (β2ARs) are important mediators of bronchorelaxation and, paradoxically, asthma development. This contradiction is likely due to the activation of dual signaling pathways that are downstream of G proteins or β-arrestins. Our group has recently shown that β-arrestin-2 acts in its classical role to desensitize and constrain β2AR-induced relaxation of both human and murine airway smooth muscle. To assess the role of β-arrestins in regulating β2AR function in asthma, we and others have utilized β-arrestin-1 and -2 knockout mice. However, it is unknown if genetic deletion of β-arrestins in these mice influences β2AR expression in the airways. Furthermore, there is lack of data on compensatory expression of βAR subtypes when either of the β-arrestins is genetically deleted, thus necessitating a detailed βAR subtype expression study in these β-arrestin knockout mice. Here we standardized a radioligand binding methodology to characterize and quantitate βAR subtype distribution in the airway smooth muscle of wild-type C57BL/6J and β-arrestin-1 and β-arrestin-2 knockout mice. Using complementary competition and single-point saturation binding assays we found that β2ARs predominate over β1ARs in the whole lung and epithelium-denuded tracheobronchial smooth muscle of C57BL/6J mice. Quantification of βAR subtypes in β-arrestin-1 and β-arrestin-2 knockout mouse lung and epithelium-denuded tracheobronchial tissue showed that, similar to the C57BL/6J mice, both knockouts display a predominance of β2AR expression. These data provide further evidence that β2ARs are expressed in greater abundance than β1ARs in the tracheobronchial smooth muscle and that loss of either β-arrestin does not significantly affect the expression or relative proportions of βAR subtypes. As β-arrestins are known to modulate β2AR function, our analysis of βAR subtype expression in β-arrestin knockout mice airways sets a reference point for future studies exploiting these knockout mice in various disease models including asthma.

• Authors: Akhil Hegde, Ryan T Strachan, Julia K L Walker
• Journal: PloS one (PLoS One) Vol. 10 Issue 2 Pg. e0116458 ( 2015) ISSN: 1932-6203 [Electronic] United States
• PMID: 25658948 (Publication Type: Journal Article, Research Support, N.I.H., Extramural)

Chemical References

• ARRB1 protein, human
• ARRB2 protein, human
• Arrb1 protein, mouse
• Arrb2 protein, mouse
• Arrestins
• Receptors, Adrenergic, beta-2
• beta-Arrestin 1
• beta-Arrestin 2
• beta-Arrestins

Topics

• Animals
• Arrestins (genetics, metabolism)
• Asthma (genetics, metabolism, pathology, physiopathology)
• Bronchi (metabolism, pathology, physiopathology)
• Humans
• Mice
• Mice, Knockout
• Muscle Relaxation
• Muscle, Smooth (metabolism, pathology, physiopathology)
• Receptors, Adrenergic, beta-2 (genetics, metabolism)
• Respiratory Mucosa (metabolism, pathology, physiopathology)
• Trachea (metabolism, pathology, physiopathology)
• beta-Arrestin 1
• beta-Arrestin 2
• beta-Arrestins