@article {Rosethorne749, author = {Elizabeth M. Rosethorne and Steven J. Charlton}, title = {Agonist-Biased Signaling at the Histamine H4 Receptor: JNJ7777120 Recruits β-Arrestin without Activating G Proteins}, volume = {79}, number = {4}, pages = {749--757}, year = {2011}, doi = {10.1124/mol.110.068395}, publisher = {American Society for Pharmacology and Experimental Therapeutics}, abstract = {The Gi/o-coupled histamine H4 receptor is highly expressed in hemopoietic cells and is a promising new target for the treatment of chronic inflammatory diseases. 1-[(5-Chloro-1H-indol-2-yl)carbonyl]-4-methyl-piperazine (JNJ7777120) has been described as a selective antagonist at the H4 receptor and is widely used to characterize the physiological role of the H4 receptor. We have investigated the pharmacological properties of JNJ7777120 using two distinct downstream signaling measurements, G protein activation and β-arrestin recruitment. The H4 receptor agonists histamine and clobenpropit, but not JNJ7777120, were able to induce [35S]GTPγS binding in membranes prepared from U2OS-H4 cells. Thioperamide, a dual H3/H4 receptor antagonist, and JNJ7777120 were both able to inhibit the [35S]GTPγS binding induced by clobenpropit. Agonists and antagonists specific for other members of the histamine receptor family had no effect in this assay format. Histamine and clobenpropit increased β-arrestin recruitment to the H4 receptor in a concentration-dependent manner. This β-arrestin recruitment could be inhibited by preincubation with thioperamide. We were surprised to find that preincubation with the H4-selective antagonist JNJ7777120 potentiated rather than antagonized the response to a submaximal concentration of clobenpropit. JNJ7777120 treatment alone resulted in an increase in β-arrestin recruitment, which again could be inhibited by preincubation with thioperamide. Schild analysis demonstrated competitive antagonism between thioperamide and both clobenpropit and JNJ7777120. Histamine and clobenpropit had comparable potencies for both [35S]GTPγS binding and β-arrestin recruitment, suggesting little difference in the levels of receptor reserve between the two assays. In conclusion, we have demonstrated that JNJ7777120 recruits β-arrestin to the H4 receptor, independent of G protein activation.}, issn = {0026-895X}, URL = {https://molpharm.aspetjournals.org/content/79/4/749}, eprint = {https://molpharm.aspetjournals.org/content/79/4/749.full.pdf}, journal = {Molecular Pharmacology} }