2 research outputs found
Expeditious Synthesis, Enantiomeric Resolution, and Enantiomer Functional Characterization of (4-(4-Bromophenyl)-3a,4,5,9b-tetrahydro‑3<i>H</i>‑cyclopenta[<i>c</i>]quinoline-8-sulfonamide (4BP-TQS): An Allosteric Agonist-Positive Allosteric Modulator of α7 Nicotinic Acetylcholine Receptors
An
expeditious microwave-assisted synthesis of 4BP-TQS, its enantiomeric
separation, and their functional evaluation is reported. Electrophysiological
characterization in Xenopus oocytes
revealed that activity exclusively resided in the (+)-enantiomer <b>1b</b> (GAT107) and (−)-enantiomer <b>1a</b> did
not affect its activity when coapplied. X-ray crystallography studies
revealed the absolute stereochemistry of <b>1b</b> to be 3a<i>R</i>,4<i>S</i>,9b<i>S</i>. <b>1b</b> represents the most potent ago-PAM of α7 nAChRs available
to date and is considered for further in vivo evaluation
Mapping Cannabinoid 1 Receptor Allosteric Site(s): Critical Molecular Determinant and Signaling Profile of GAT100, a Novel, Potent, and Irreversibly Binding Probe
One of the most abundant
G-protein coupled receptors (GPCRs) in
brain, the cannabinoid 1 receptor (CB1R), is a tractable therapeutic
target for treating diverse psychobehavioral and somatic disorders.
Adverse on-target effects associated with small-molecule CB1R orthosteric
agonists and inverse agonists/antagonists have plagued their translational
potential. Allosteric CB1R modulators offer a potentially safer modality
through which CB1R signaling may be directed for therapeutic benefit.
Rational design of candidate, druglike CB1R allosteric modulators
requires greater understanding of the architecture of the CB1R allosteric
endodomain(s) and the capacity of CB1R allosteric ligands to tune
the receptor’s information output. We have recently reported
the synthesis of a focused library of rationally designed, covalent
analogues of Org27569 and PSNCBAM-1, two prototypic CB1R negative
allosteric modulators (NAMs). Among the novel, pharmacologically active
CB1R NAMs reported, the isothiocyanate GAT100 emerged as the lead
by virtue of its exceptional potency in the [<sup>35</sup>S]ÂGTPγS
and β-arrestin signaling assays and its ability to label CB1R
as a covalent allosteric probe with significantly reduced inverse
agonism in the [<sup>35</sup>S]ÂGTPγS assay as compared to Org27569.
We report here a comprehensive functional profiling of GAT100 across
an array of important downstream cell-signaling pathways and analysis
of its potential orthosteric probe-dependence and signaling bias.
The results demonstrate that GAT100 is a NAM of the orthosteric CB1R
agonist CP55,940 and the endocannabinoids 2-arachidonoylglycerol and
anandamide for β-arrestin1 recruitment, PLCβ3 and ERK1/2
phosphorylation, cAMP accumulation, and CB1R internalization in HEK293A
cells overexpressing CB1R and in Neuro2a and ST<i>Hdh</i><sup>Q7/Q7</sup> cells endogenously expressing CB1R. Distinctively,
GAT100 was a more potent and efficacious CB1R NAM than Org27569 and
PSNCBAM-1 in all signaling assays and did not exhibit the inverse
agonism associated with Org27569 and PSNCBAM-1. Computational docking
studies implicate C7.38(382) as a key feature of GAT100 ligand-binding
motif. These data help inform the engineering of newer-generation,
druggable CB1R allosteric modulators and demonstrate the utility of
GAT100 as a covalent probe for mapping structure–function correlates
characteristic of the druggable CB1R allosteric space