A(2b) adenosine receptors can change their spots.
Recently, a central role for the A(2b) adenosine receptor in a variety of cardiovascular functions including inflammation, erectile function, coronary artery dilation, asthma and cardioprotection has been demonstrated. Despite this evidence, the low-affinity A(2b) adenosine receptor is still poorly understood. This receptor appears to be very promiscuous in its coupling. In most tissues, it couples to G(s) much like its cousin, the A(2a) adenosine receptor, but in mast cells and now, most recently, in cardiac fibroblasts, the A(2b) receptor also couples to G(q). Because of its low affinity, this receptor was originally thought unlikely to play any important physiological role. But the sensitivity of A(2b) adenosine receptors can be greatly increased by interaction with protein kinase C (PKC) making this receptor, under various conditions, both an activator and a target of PKC. We have recently documented a third coupling involving G(i). This plasticity and versatility of A(2b) adenosine receptors position them as potential triggers of signalling in multiple signalling cascades in many physiological responses, making this a most interesting receptor indeed.
Cohen
Michael V
MV
Department of Physiology, University of South Alabama, Mobile, 36688, USA. mcohen@usouthal.edu
Yang
Xiulan
X
Downey
James M
JM
D000818:Animals; D043802:GTP-Binding Protein alpha Subunits, Gq-G11 / Q000378:metabolism; D006801:Humans; D011485:Protein Binding; D011493:Protein Kinase C / Q000378:metabolism; D043704:Receptor, Adenosine A2B / Q000378:metabolism / Q000502:physiology*
D043704:Receptor, Adenosine A2B; D011493:Protein Kinase C; D043802:GTP-Binding Protein alpha Subunits, Gq-G11
Br J Pharmacol. 2010 Apr;159(8):1598-607
20050850
J Physiol Pharmacol. 2005 Dec;56(4):587-97
16391416
Cardiovasc Res. 2006 May 1;70(2):308-14
16545350
Cardiovasc Res. 2001 Oct;52(1):25-39
11557231
Circ Res. 1995 Feb;76(2):242-51
7834835
J Mol Cell Cardiol. 2007 Sep;43(3):262-71
17632123
Am J Physiol. 1996 May;270(5 Pt 2):H1655-61
8928871
Mol Pharmacol. 1999 Oct;56(4):705-13
10496952
Pharmacol Rev. 1997 Dec;49(4):381-402
9443164
Cell Signal. 2003 Sep;15(9):813-27
12834807
Am J Physiol Heart Circ Physiol. 2006 Jan;290(1):H441-9
16155103
Am J Physiol Heart Circ Physiol. 2002 Feb;282(2):H437-44
11788390
Circulation. 1991 Jul;84(1):350-6
2060105
Expert Opin Emerg Drugs. 2007 Sep;12(3):479-92
17874974
J Clin Invest. 2006 Jul;116(7):1913-23
16823489