Discovery of Compounds that Positively Modulate the High Affinity Choline Transporter

Abstract

Cholinergic hypofunction is associated with decreased attention and cognitive deficits in the central nervous system in addition to compromised motor function. Consequently, stimulation of cholinergic neurotransmission is a rational therapeutic approach for the potential treatment of a variety of neurological conditions. High affinity choline uptake (HACU) into acetylcholine (ACh)-synthesizing neurons is critically mediated by the sodium- and pH-dependent high-affinity choline transporter (CHT, encoded by the SLC5A7 gene). This transporter is comparatively well-characterized but otherwise unexplored as a potential drug target. We therefore sought to identify small molecules that would enable testing of the hypothesis that positive modulation of CHT mediated transport would enhance activity-dependent cholinergic signaling. We utilized existing and novel screening techniques for their ability to reveal both positive and negative modulation of CHT using literature tools. A screening campaign was initiated with a bespoke compound library comprising both the Pfizer Chemogenomic Library (CGL) of 2,753 molecules designed specifically to help enable the elucidation of new mechanisms in phenotypic screens and 887 compounds from a virtual screening campaign to select molecules with field-based similarities to reported negative and positive allosteric modulators. We identified a number of previously unknown active and structurally distinct molecules that could be used as tools to further explore CHT biology or as a starting point for further medicinal chemistry.

Neuroprotective Activity of Extract of Celery (Apium Graveolens) in Insilico Study

“…These three proteins assist in the transmembrane transporter that imports choline from the extracellular space into high-affinity neurons. Choline absorption is the rate-limiting step in acetylcholine synthesis 10 .…”

The evolution of the pilocarpine animal model of status epilepticus

“…This occurs because hemicholinium-3 prevents the re-uptake of choline by high-affinity choline transporters at the presynaptic membrane, causing an 80% reduction in the normal acetylcholine concentration ( Freeman et al., 1975 ). This indirectly reduces the efficiency of the M1 muscarinic acetylcholine receptors on the postsynaptic membrane ( Choudhary et al., 2017 ), highlighting the importance of presynaptic cholinergic activity in the pilocarpine model of SE. Similarly, studies have shown that seizure activity in pilocarpine models can be blocked by a 15-minute pre-treatment with diazepam (a common AED), and initial tonic-clonic seizures can also be terminated via diazepam administration, making this a suitable model for SE ( Jope et al., 1986 ).…”

Integration of Lead Discovery Tactics and the Evolution of the Lead Discovery Toolbox

“…Ligand-based virtual screening is another powerful knowledge-based approach that is often integrated with other approaches in the lead discovery toolbox. This is exemplified by the work of a team at Pfizer, who were interested in compounds that are modulators of the high-affinity choline transporter (CHT), 77 to enable testing of the hypothesis that positive modulation of CHT-mediated transport would enhance activity-dependent cholinergic signaling and therefore be an attractive therapeutic target. This project had a common scenario, with a small number of literature compounds (orthosteric inhibitors, negative allosteric modulators, and putative positive modulators), none of which were quite what the project needed.…”