Session Type: Abstract Submissions (ACR)
Background/Purpose A2AR stimulation promotes collagen 1 and 3 (Col1 and Col3) synthesis, principal mediators of fibrosis and scarring. We have recently demonstrated that the A2AR is a fine-tune modulator of collagen balance that signals via PKA/EPAC2/AKT but is independent of Smad2/3 signaling. Wnt signaling is an important player in the progression of fibrosis, and other recent studies have suggested that cAMP and Wnt pathways converge. Since A2AR is Gs-linked and increases cAMP, we determined whether A2AR and Wnt signaling interact.
Methods : Primary human dermal fibroblasts (<5 passages) were stimulated by the A2AR-selective agent CGS21680 (1μM) and β-catenin, dephosphorylated β-catenin and β-catenin phospho-Ser552 levels were determined in cytosolic and nuclear fractions by Western Blot. Nuclear translocation of β-catenin was determined by confocal microscopy. β-catenin was knocked down by transfection with specific-siRNA or scrambled-siRNA and protein levels determined by Western Blot.
Results Stimulation of A2AR rapidly (15 min) increases cellular β-catenin levels to 196±13% of control (N=3, P<0.01). Similarly CGS21680 stimulates de-phosphorylation of β-catenin (188±27% of control; N=5, P<0.05) and promotes β-catenin phosphorylation at Ser 552 (239±15% of control; N=5, P<0.001), the site of β-catenin activation by AKT. Furthermore, CGS21680 stimulates translocation of β-catenin to the nucleus, as confirmed by confocal microscopy and Western Blot. We next knocked down β-catenin (54±5% decrease in β-catenin siRNA vs scramble siRNA; N=10, P<0.001) and determined the effect of A2AR stimulation on collagen production. A2AR-stimulated increases in Col1 scramble-siRNA transfected cells (63±22% increase, N=7) which were unaffected by β-catenin knockdown (53±17% increase, N=7). In contrast, β-catenin knockdown abrogates A2AR-stimulated increments in Col3 synthesis by 73% (scramble-siRNA 66±14% increase of Col3 vs β-catenin-siRNA 18±16% increase of Col3; P<0.05, N=8).
Conclusion Our results strongly indicate that A2AR stimulation activates both canonical and non-canonical Wnt pathways for increased Col3 synthesis, leading to dermal fibrosis and excessive scarring.
B. N. Cronstein,
NYU School of Medicine,
Eli Lilly and Company,
Rheumatology Reseach Foundation,
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/adenosine-a2a-receptor-a2ar-promotes-collagen-type-3-expression-via-%ce%b2-catenin-activation/