The β2-adrenergic receptor (β2AR) has been a model system for understanding regulatory mechanisms of G-protein–coupled receptor (GPCR) actions and plays a significant role in cardiovascular and pulmonary diseases. Because all known β-adrenergic receptor drugs target the orthosteric binding site of the receptor, we set out to isolate allosteric ligands for this receptor by panning DNA-encoded small-molecule libraries comprising 190 million distinct compounds against purified human β2AR. Here, we report the discovery of a small-molecule negative allosteric modulator (antagonist), compound 15 [([4-((2S)-3-(((S)-3-(3-bromophenyl)-1-(methylamino)-1-oxopropan-2-yl)amino)-2-(2-cyclohexyl-2-phenylacetamido)-3-oxopropyl)benzamide], exhibiting a unique chemotype and low micromolar affinity for the β2AR. Binding of 15 to the receptor cooperatively enhances orthosteric inverse agonist binding while negatively modulating binding of orthosteric agonists. Studies with a specific antibody that binds to an intracellular region of the β2AR suggest that 15 binds in proximity to the G-protein binding site on the cytosolic surface of the β2AR. In cell-signaling studies, 15 inhibits cAMP production through the β2AR, but not that mediated by other Gs-coupled receptors. Compound 15 also similarly inhibits β-arrestin recruitment to the activated β2AR. This study presents an allosteric small-molecule ligand for the β2AR and introduces a broadly applicable method for screening DNA-encoded small-molecule libraries against purified GPCR targets. Importantly, such an approach could facilitate the discovery of GPCR drugs with tailored allosteric effects.

Neurodevelopmental defects in humans represent a clinically heterogeneous group of disorders. Here, we report the genetic and functional dissection of a multigenerational pedigree with an X-linked syndromic disorder hallmarked by microcephaly, growth retardation, and seizures. Using an X-linked intellectual disability (XLID) next-generation sequencing diagnostic panel, we identified a novel missense mutation in the gene encoding 60S ribosomal protein L10 (RPL10), a locus associated previously with autism spectrum disorders (ASD); the p.K78E change segregated with disease under an X-linked recessive paradigm while, consistent with causality, carrier females exhibited skewed X inactivation. To examine the functional consequences of the p.K78E change, we modeled RPL10 dysfunction in zebrafish. We show that endogenous rpl10 expression is augmented in anterior structures, and that suppression decreases head size in developing morphant embryos, concomitant with reduced bulk translation and increased apoptosis in the brain. Subsequently, using in vivo complementation, we demonstrate that p.K78E is a loss-of-function variant. Together, our findings suggest that a mutation within the conserved N-terminal end of RPL10, a protein in close proximity to the peptidyl transferase active site of the 60S ribosomal subunit, causes severe defects in brain formation and function. N EURODEVELOPMENTAL defects in humans represent a diagnostic challenge. Displaying marked phenotypic overlap, examples include autism spectrum disorders (ASD), intellectual disability (ID), microcephaly, and seizures; in some instances, common genetic defects can underscore each of these clinical entities. For example, mutations in the voltage-gated sodium channel Na v 1.2 encoded by SCN2A are associated with the manifestation of early infantile epilepsy (Sugawara et al. 2001). However, recent exome sequencing studies have also identified SCN2A mutations as rare contributors to disease in autism cohorts, thereby expanding the phenotypic spectrum underscored by Na v 1.2 channel dysfunction (Sanders et al. 2012). A gender bias of 1.3-1.4 males to 1 female with a neurodevelopmental disorder has complicated further our mechanistic understanding of such defects (Leonard and Wen 2002;Ellison et al. 2013). One obvious explanation for an unbalanced representation of the sexes among individuals with a structural or functional brain defect is an abundance of developmentally important genes on the X chromosome. To date, .100 genes have been associated with ASD, ID, microcephaly, or seizures primarily in hemizygous males and, to some extent, their carrier mothers (De Brouwer et al. 2007;Tarpey et al. 2009;Lubs et al. 2012).Here, we report the genetic dissection of a novel form of X-linked human genetic disease characterized by microcephaly, seizures, growth retardation, and hypotonia. Combined genetic, functional, and biochemical assays suggest that a missense mutation in RPL10, a component of the 60S large ribosomal subunit, can cause syndromic central nervo...