Open AccessQuantification of Beta Adrenergic Receptor Subtypes in Beta-Arrestin Knockout Mouse Airways
Author(s) -
Akhil Hegde,
Ryan T. Strachan,
Julia K. L. Walker
Publication year - 2015
Publication title -
plos one
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.99
H-Index - 332
ISSN - 1932-6203
DOI - 10.1371/journal.pone.0116458
Subject(s) - knockout mouse , arrestin , receptor , biology , microbiology and biotechnology , gene knockout , respiratory epithelium , g protein coupled receptor , signal transduction , epithelium , medicine , gene , genetics
In allergic asthma Beta 2 adrenergic receptors (β 2 ARs) 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 β 2 AR-induced relaxation of both human and murine airway smooth muscle. To assess the role of β-arrestins in regulating β 2 AR 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 β 2 AR 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 β 2 ARs predominate over β 1 ARs 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 β 2 AR expression. These data provide further evidence that β 2 ARs are expressed in greater abundance than β 1 ARs 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 β 2 AR 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.