RT Journal Article
SR Electronic
T1 Delineation of the GPRC6A Receptor Signaling Pathways Using a Mammalian Cell Line Stably Expressing the Receptor
JF Journal of Pharmacology and Experimental Therapeutics
JO J Pharmacol Exp Ther
FD American Society for Pharmacology and Experimental Therapeutics
SP 298
OP 309
DO 10.1124/jpet.113.206276
VO 347
IS 2
A1 Stine Engesgaard Jacobsen
A1 Lenea Nørskov-Lauritsen
A1 Alex Rojas Bie Thomsen
A1 Sanela Smajilovic
A1 Petrine Wellendorph
A1 Niklas H. P. Larsson
A1 Anders Lehmann
A1 Vikram Kjøller Bhatia
A1 Hans Bräuner-Osborne
YR 2013
UL http://jpet.aspetjournals.org/content/347/2/298.abstract
AB The GPRC6A receptor is a recently “deorphanized” class C G protein–coupled receptor. We and others have shown that this receptor is coactivated by basic l-α-amino acids and divalent cations, whereas other groups have also suggested osteocalcin and testosterone to be agonists. Likewise, the GPRC6A receptor has been suggested to couple to multiple G protein classes albeit via indirect methods. Thus, the exact ligand preferences and signaling pathways are yet to be elucidated. In the present study, we generated a Chinese hamster ovary (CHO) cell line that stably expresses mouse GPRC6A. In an effort to establish fully the signaling properties of the receptor, we tested representatives of four previously reported GPRC6A agonist classes for activity in the Gq, Gs, Gi, and extracellular-signal regulated kinase signaling pathways. Our results confirm that GPRC6A is activated by basic l-α-amino acids and divalent cations, and for the first time, we conclusively show that these responses are mediated through the Gq pathway. We were not able to confirm previously published data demonstrating Gi- and Gs-mediated signaling; neither could we detect agonistic activity of testosterone and osteocalcin. Generation of the stable CHO cell line with robust receptor responsiveness and optimization of the highly sensitive homogeneous time resolved fluorescence technology allow fast assessment of Gq activation without previous manipulations like cotransfection of mutated G proteins. This cell-based assay system for GPRC6A is thus useful in high-throughput screening for novel pharmacological tool compounds, which are necessary to unravel the physiologic function of the receptor.