The Interaction of Organic Cation Transporters 1-3 and PMAT with Psychoactive Substances

Interaction Profiles of Central Nervous System Active Drugs at Human Organic Cation Transporters 1–3 and Human Plasma Membrane Monoamine Transporter

“…Currently, only few selective hOCT or hPMAT inhibitors are known, which can be explained by the high degree of sequence homology between transporters [ 25 ]. In particular, hOCT1 and 2 share approximately 70% amino acid sequence identity [ 2 , 14 ]. It is therefore not surprising to see an overlap of compounds interacting with hOCT1 and 2.…”

“…Amino acid residues that are critical for substrate specificity, which are localized in regions formed by transmembrane helices crucial for substrate binding, were found to differ between OCT1 and OCT2, and might explain variations in compound interactions with those transporters [ 42 , 43 ]. Still, the exact molecular basis for preference of compounds for hOCT1 or 2 has not been clearly established yet [ 2 , 14 , 44 ]. While we could not solve this gap in knowledge, our investigation led to the discovery of scaffolds that can be used for the development of selective inhibitors of OCTs, expanding pharmacological and structural understanding of this transporter family.…”

“…HEK293 cells were transfected with a plasmid, encoding the transporter of interest and an N-terminal YFP-tag, carried out using jetPRIME (Polyplus Transfection; (VWR International GmbH, Vienna, Austria)) reagent (for a 10 cm dish with 1–2 × cells in 10 mL serum containing medium at 60–80% confluency: 500 L jetPRIME buffer, 10 g DNA and 20 L jetPRIME reagent) and selection pressure maintained for two weeks [ 2 , 54 , 55 ]. Subsequently, 500,000 cells were FACS-sorted (fluorescence-activated cell sorting) according to expression level to establish cell lines stably expressing the protein of interest.…”

“…Organic cation transporter subtypes 1-3 (OCT1–3; SLC22A1–3, respectively; OCTs) and the plasma membrane monoamine transporter (PMAT; SLC29A4) are poly-specific facilitative transporters which are involved in the uptake and elimination of various endogenous compounds, most notably monoamines, as well as of drugs, xenobiotics, and toxins [ 1 ]. In addition to the high-affinity, low-capacity solute carrier 6 (SLC6) neurotransmitter-sodium symporters of norepinephrine (norepinephrine transporter; NET; SLC6A2), dopamine (dopamine transporter; DAT; SLC6A3) and serotonin (serotonin transporter; SERT; SLC6A4), the low-affinity, high-capacity OCTs as well as PMAT are of paramount importance for the maintenance of monoaminergic equilibrium in the brain [ 2 , 3 ]. In addition, OCTs contribute to protection against noxious compounds by intestinal absorption as well as hepatic and renal excretion [ 4 , 5 , 6 ].…”

“…Given the plethora of CNS active substances that are well-known for their interplay with SLC6 neurotransmitter-sodium symporters (summarized as monoamine transporters; MATs), there is also a growing amount of interest in their interaction with the human OCTs as well as PMAT, since they are less well-researched potential targets in the monoamingergic system [ 16 , 17 , 18 , 19 , 20 , 21 ]. We have recently reported that several psychoactive substances, classified primarily as inhibitors or substrates of the MATs, equipotently interact with certain OCTs [ 2 , 22 ].…”