No abstract

G protein-coupled receptors (GPCRs) are essential mediators of cellular signaling and important targets of drug action. Of the approximately 350 non-olfactory human GPCRs, more than 100 are still considered “orphans” as their endogenous ligand(s) remain unknown. Here, we describe a unique open-source resource that provides the capacity to interrogate the druggable human GPCR-ome via a G protein-independent β-arrestin recruitment assay. We validate this unique platform at more than 120 non-orphan human GPCR targets, demonstrate its utility for discovering new ligands for orphan human GPCRs, and describe a method (PRESTO-TANGO; Parallel Receptor-ome Expression and Screening via Transcriptional Output - TANGO) for the simultaneous and parallel interrogation of the entire human GPCR-ome.

As a result of superior efficacy and overall tolerability, atypical antipsychotic drugs have become the treatment of choice for schizophrenia and related disorders, despite their side effects. Weight gain is a common and potentially serious complication of some antipsychotic drug therapy, and may be accompanied by hyperlipidemia, hypertension and hyperglycemia and, in some extreme cases, diabetic ketoacidosis. The molecular mechanism(s) responsible for antipsychotic drug-induced weight gain are unknown, but have been hypothesized to be because of interactions of antipsychotic drugs with several neurotransmitter receptors, including 5-HT 2A and 5-HT 2C serotonin receptors, H 1 -histamine receptors, a 1 -and a 2 -adrenergic receptors, and m3-muscarinic receptors. To determine the receptor(s) likely to be responsible for antipsychotic-drug-induced weight gain, we screened 17 typical and atypical antipsychotic drugs for binding to 12 neurotransmitter receptors. H 1 -histamine receptor affinities for this group of typical and atypical antipsychotic drugs were significantly correlated with weight gain (Spearman r ¼ À0.72; po0.01), as were affinities for a 1A adrenergic (r ¼ À0.54; po0.05), 5-HT 2C (r ¼ À0.49; po0.05) and 5-HT 6 receptors (r ¼ À0.54; po0.05), whereas eight other receptors' affinities were not. A principal components analysis showed that affinities at the H 1 , a 2A , a 2B , 5-HT 2A , 5-HT 2C , and 5-HT 6 receptors were most highly correlated with the first principal component, and affinities for the D 2 , 5-HT 1A , and 5-HT 7 receptors were most highly correlated with the second principal component. A discriminant functions analysis showed that affinities for the H 1 and a 1A receptors were most highly correlated with the discriminant function axis. The discriminant function analysis, as well as the affinity for the H 1 -histamine receptor alone, correctly classified 15 of the 17 drugs into two groups; those that induce weight gain and those that do not. Because centrally acting H 1 -histamine receptor antagonists are known to induce weight gain with chronic use, and because H 1 -histamine receptor affinities are positively correlated with weight gain among typical and atypical antipsychotic drugs, it is recommended that the next generation of atypical antipsychotic drugs be screened to avoid H 1 -histamine receptors.

The human polyomavirus, JCV, causes the fatal demyelinating disease progressive multifocal leukoencephalopathy in immunocompromised patients. We found that the serotonergic receptor 5HT2AR could act as the cellular receptor for JCV on human glial cells. The 5HT2A receptor antagonists inhibited JCV infection, and monoclonal antibodies directed at 5HT2A receptors blocked infection of glial cells by JCV, but not by SV40. Transfection of 5HT2A receptor-negative HeLa cells with a 5HT2A receptor rescued virus infection, and this infection was blocked by antibody to the 5HT2A receptor. A tagged 5HT2A receptor colocalized with labeled JCV in an endosomal compartment following internalization. Serotonin receptor antagonists may thus be useful in the treatment of progressive multifocal leukoencephalopathy.