Pharmacological identification of a guanidine-containing β-alanine analogue with low micromolar potency and selectivity for the betaine/GABA transporter 1 (BGT1).
The γ-aminobutyric acid (GABA) transporters (GATs) are key membrane transporter proteins involved in the termination of GABAergic signaling at synapses in the mammalian brain and proposed drug targets in neurological disorders such as epilepsy. To date, four different GAT subtypes have been identified: GAT1, GAT2, GAT3 and the betaine/GABA transporter 1 (BGT1). Owing to the lack of potent and subtype selective inhibitors of the non-GAT1 GABA transporters, the physiological role and therapeutic potential of these transporters remain to be fully understood. Based on bioisosteric replacement of the amino group in β-alanine or GABA, a series of compounds was generated, and their pharmacological activity assessed at human GAT subtypes. Using a cell-based [(3)H]GABA uptake assay, several selective inhibitors at human BGT1 were identified. The guanidine-containing compound 9 (2-amino-1,4,5,6-tetrahydropyrimidine-5-carboxylic acid hydrochloride) displayed more than 250 times greater potency than the parent compound β-alanine at BGT1 and is thus the most potent inhibitor reported to date for this subtype (IC50 value of 2.5 µM). In addition, compound 9 displayed about 400, 16 and 40 times lower inhibitory potency at GAT1, GAT2 and GAT3, respectively. Compound 9 was shown to be a substrate for BGT1 and to have an overall similar pharmacological profile at the mouse orthologue. Compound 9 constitutes an interesting pharmacological tool for specifically investigating the cellular pharmacology of BGT1 and is the first small-molecule substrate identified with such a high selectivity for BGT1 over the three other GAT subtypes.
Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100, Copenhagen, Denmark.
Anas
A
Al-Khawaja
Jette G
JG
Petersen
Maria
M
Damgaard
Mette H
MH
Jensen
Stine B
SB
Vogensen
Maria E K
ME
Lie
Bolette
B
Kragholm
Hans
H
Bräuner-Osborne
Rasmus P
RP
Clausen
Bente
B
Frølund
Petrine
P
Wellendorph
D000818:Animals; D016466:CHO Cells; D002352:Carrier Proteins / Q000378:metabolism*; D006224:Cricetinae; D003412:Cricetulus; D050485:GABA Plasma Membrane Transport Proteins; D019791:Guanidine / Q000378:metabolism*; D015091:beta-Alanine / Q000378:metabolism*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D002352:Carrier Proteins; D050485:GABA Plasma Membrane Transport Proteins; D015091:beta-Alanine; C072207:betaine plasma membrane transport proteins; D005680:gamma-Aminobutyric Acid; D019791:Guanidine