MARCH2 promotes endocytosis and lysosomal sorting of carvedilol-bound beta(2)-adrenergic receptors

作者：Han Sang oh; Xiao Kunhong; Kim Jihee; Wu Jiao Hui; Wisler James W; Nakamura Nobuhiro; Freedman Neil J; Shenoy Sudha K^*

来源：The Journal of Cell Biology, 2012, 199(5): 817-830.

DOI：10.1083/jcb.201208192

Lysosomal degradation of ubiquitinated beta(2)-adrenergic receptors (beta(2)ARs) serves as a major mechanism of long-term desensitization in response to prolonged agonist stimulation. Surprisingly, the beta AR antagonist carvedilol also induced ubiquitination and lysosomal trafficking of both endogenously expressed beta(2)ARs in vascular smooth muscle cells (VSMCs) and overexpressed Flag-beta(2)ARs in HEK-293 cells. Carvedilol prevented beta(2)AR recycling, blocked recruitment of Nedd4 E3 ligase, and promoted the dissociation of the deubiquitinases USP20 and USP33. Using proteomics approaches (liquid chromatographytandem mass spectrometry), we identified that the E3 ligase MARCH2 interacted with carvedilol-bound beta(2)AR. The association of MARCH2 with internalized beta(2)ARs was stabilized by carvedilol and did not involve beta-arrestin. Small interfering RNA-mediated down-regulation of MARCH2 ablated carvedilol-induced ubiquitination, endocytosis, and degradation of endogenous beta(2)ARs in VSMCs. These findings strongly suggest that specific ligands recruit distinct E3 ligase machineries to activated cell surface receptors and direct their intracellular itinerary. In response to beta blocker therapy with carvedilol, MARCH2 E3 ligase activity regulates cell surface beta(2)AR expression and, consequently, its signaling.

• 出版日期2012-11-26