Prolyl hydroxylase 2: a novel regulator of β2 -adrenoceptor internalization.
Bottom Line: However, it remains to be clarified whether or how PHDs are involved in the regulation of β(2) -adrenoceptor (β(2) -AR) signalling.Here we show that PHD2 can modulate the rate of β(2) -AR internalization through interactions with β-arrestin 2.PHD2 hydroxylates β-arrestin 2 at the proline (Pro)(176), Pro(179) and Pro(181) sites, which retards the recruitment of β-arrestin 2 to the plasma membrane and inhibits subsequent co-internalization with β(2) -AR into the cytosol. β(2) -AR internalization is critical to control the temporal and spatial aspects of β(2) -AR signalling.
Affiliation: Key Laboratory of Arrhythmias, Ministry of Education, China (East Hospital, Tongji University School of Medicine), Shanghai, China.Show MeSH
Mentions: The process of β-arrestin 2-mediated β2-AR internalization involves the initial translocation of β-arrestin 2 to the plasma membrane, the subsequent formation of the membrane cluster, and β-arrestin 2/β2-AR co-internalization into the cytosol . To determine how PHD2 affected β-arrestin 2 movement, we monitored the agonist-dependent trafficking of β-arrestin 2-GFP in β2-AR-293 cells in response to receptor activation (Fig. 5A). Membrane clusters were detected as early as 1 min. after the addition of ISO. Compared to the control group, PHD2 overexpression exhibited delayed formation of membrane clusters (34.44%± 1.92% versus 25.56 ± 3.85%, Fig. 5B). The differences in internal clusters were first observed at 10 min., with a greater internalization percentage in control cells than in PHD2-overexpressing cells (28.89 ± 3.85% versus 20 ± 3.33%). The greatest internalization percentages (46.67 ± 3.33% versus 33.33 ± 3.33%) were observed at 40 min. for both the control and PHD2 overexpressing cells, but the value is significantly higher in control cells. These results support and strengthen the findings observed in Fig. 1A, namely that PHD2 retards β2-AR internalization. During the experiment, Western blots revealed that PHD2 expression level had no effect on the endogenous β-arrestin 2 expression (Fig. 5C). Taken together, these results suggest that PHD2 delays β2-AR internalization by retarding the recruitment of β-arrestin 2 to the plasma membrane and its subsequent co-internalization with β2-AR.
Affiliation: Key Laboratory of Arrhythmias, Ministry of Education, China (East Hospital, Tongji University School of Medicine), Shanghai, China.