PKA-mediated phosphorylation of the beta1-adrenergic receptor promotes Gs/Gi switching.
Recently, it has been shown that PKA-mediated phosphorylation of the beta(2)-adrenergic receptor (beta(2)-AR) by the cyclic AMP-dependent protein kinase (PKA) reduces its affinity for G(s) and increases its affinity for G(i). Here we demonstrate that, like the beta(2)-AR, the beta(1)-AR is also capable of "switching" its coupling from G(s) to G(i) in a PKA-dependent manner. The beta(1)-AR is capable of activating adenylate cyclase via G(s), and can also activate the extracellular-regulated kinases, p44 and p42 (ERK1/2). In transfected CHO cells, the observed beta(1)-AR-mediated activation of ERK is both sensitive to pertussis toxin (PTX), indicating involvement of G(i)/G(o), and to the PKA inhibitor, H-89. beta(1)-ARs with PKA phosphorylation sites mutated to alanines are unable to activate ERK. Mutating these same residues to aspartic acid, mimicking PKA phosphorylation, leads to a decrease in G(s)-stimulated cAMP accumulation and an increase in PTX-sensitive ERK activation. These results strongly support the hypothesis that the beta(1)-AR, like the beta(2)-AR, can undergo PKA-dependent "G(s)/G(i) switching".
Martin
Negin P
NP
Howard Hughes Medical Institute, Duke University Medical Center, Box 3821, Durham, NC 27710, USA.
Whalen
Erin J
EJ
Zamah
Musa A
MA
Pierce
Kristen L
KL
Lefkowitz
Robert J
RJ
D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D016466:CHO Cells; D006224:Cricetinae; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000378:metabolism*; D019205:GTP-Binding Protein alpha Subunits, Gs / Q000378:metabolism*; D009154:Mutation; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D018342:Receptors, Adrenergic, beta-1 / Q000378:metabolism*; D013997:Time Factors; D015533:Transcriptional Activation; D014162:Transfection
D018342:Receptors, Adrenergic, beta-1; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D019205:GTP-Binding Protein alpha Subunits, Gs; D000262:Adenylyl Cyclases