Biology subjects

Nilson, A. N.

Publications and source records attributed to Nilson, A. N..

3 recordsLinked to original sources

bioRxiv2025

Multiple Allosteric Sites Allow for Synergistic Enhancement of GPCR Signaling

Allosteric modulation of G protein-coupled receptors (GPCRs) is an emerging therapeutic paradigm that has proven effective, yet the cooperative action of multiple modulators remains unexplored. Here, we reveal how positive allosteric modulators (PAMs) synergistically enable extraordinary signal amplification through the D1 dopamine receptor (D1R). We developed UNC9815 and UNC10062 as enhanced D1R PAMs from the parent compound MLS6585, and then employed cryo-electron microscopy to reveal concurrent occupancy of three distinct allosteric sites by PAMs of different scaffolds, including LY3154207, BMS-A1, and our UNC compounds. Remarkably, we discovered two adjacent allosteric pockets at the transmembrane helix (TM) 1-7 interface: BMS-A1 occupies an intracellular site promoting activation through TM7 conformational shifts, while the UNC compounds complementarily stabilize the extracellular side of the interface. When combined with LY3154207, this cooperative architecture enhances dopamine potency by more than 1,000-fold. These findings elucidate the first structural blueprint for multi-site GPCR cooperativity, unlocking transformative therapeutic strategies inaccessible to orthosteric and single- site allosteric drugs.

molecular biology↗

bioRxiv2024

Functionally selective dopamine D1 receptor endocytosis and signaling by catechol and non-catechol agonists

The dopamine D1 receptor (D1R) has fundamental roles in voluntary movement and memory and is a validated drug target for neurodegenerative and neuropsychiatric disorders. However, previously developed D1R selective agonists possess a catechol moiety which displays poor pharmacokinetic properties. The first selective non-catechol D1R agonists were recently discovered and unexpectedly many of these ligands showed G protein biased signaling. Here, we investigate both catechol and non-catechol D1R agonists to validate potential biased signaling and examine if this impacts agonist-induced D1R endocytosis. We determined that most, but not all, non-catechol agonists display G protein biased signaling at the D1R and have reduced or absent {beta}-arrestin recruitment. A notable exception was compound (Cmpd) 19, a non-catechol agonist with full efficacy at both D1R-G protein or D1R-{beta}-arrestin pathways. In addition, the catechol ligand A-77636 was a highly potent, super agonist for D1R-{beta}-arrestin activity. When examined for agonist-induced D1R endocytosis, balanced agonists SKF-81297 and Cmpd 19 induced robust D1R endocytosis while the G protein biased agonists did not. The {beta}-arrestin super agonist, A-77636, showed significantly increased D1R endocytosis. Moreover, {beta}-arrestin recruitment efficacy of tested agonists strongly correlated with total D1R endocytosis. Taken together, these results indicate the degree of D1R signaling functional selectivity profoundly impacts D1R endocytosis regardless of pharmacophore. The range of functional selectivity of these D1R agonists will provide valuable tools to further investigate D1R signaling, trafficking and therapeutic potential. Significance StatementThe D1R is a validated therapeutic target and the recently discovered non-catechol D1R agonists have translational potential. We have systematically characterized several structurally distinct D1R agonists including non-catechols with balanced or G protein biased activity. When examined for agonist-induced D1R endocytosis, balanced agonists induced robust D1R endocytosis while G protein biased agonists did not. These results indicate the degree of D1R signaling functional selectivity profoundly impacts receptor endocytosis. This work also independently validates agonist tools to further investigate D1R activation in basic and translational research.

pharmacology and toxicology↗

bioRxiv2022

Identification and Characterization of ML321: a Novel and Highly Selective D2 Dopamine Receptor Antagonist with Efficacy in Animal Models that Predict Atypical Antipsychotic Activity

We have developed and characterized a novel D2R antagonist with exceptional GPCR selectivity - ML321. In functional profiling screens of 168 different GPCRs, ML321 showed little activity beyond potent inhibition of the D2R, and to a lesser extent the D3R, demonstrating excellent receptor selectivity. The D2R selectivity of ML321 may be related to the fact that, unlike other monoaminergic ligands, ML321 lacks a positively charged amine group and adopts a unique binding pose within the orthosteric binding site of the D2R. PET imaging studies in non-human primates demonstrated that ML321 penetrates the CNS and occupies the D2R in a dose-dependent manner. Behavioral paradigms in rats demonstrate that ML321 can selectively antagonize a D2R-mediated response (hypothermia) while not affecting a D3R-mediated response (yawning) using the same dose of drug, thus indicating exceptional in vivo selectivity. We also investigated the effects of ML321 in animal models that are predictive of antipsychotic efficacy in humans. We found that ML321 attenuates both amphetamine- and phencyclidine-induced locomotor activity and restored pre-pulse inhibition (PPI) of acoustic startle in a dose-dependent manner. Surprisingly, using doses that were maximally effective in both the locomotor and PPI studies, ML321 was relatively ineffective in promoting catalepsy. Kinetic studies revealed that ML321 exhibits slow-on and fast-off receptor binding rates, similar to those observed with atypical antipsychotics with reduced extrapyramidal side effects. Taken together, these observations suggest that ML321, or a derivative thereof, may exhibit "atypical" antipsychotic activity in humans with significantly fewer side effects than observed with currently FDA-approved D2R antagonists.

pharmacology and toxicology↗