Interspecies comparison of the functional characteristics of plasma membrane monoamine transporter (PMAT) between human, rat and mouse

Abstract

Plasma membrane monoamine transporter (PMAT) is a newly discovered monoamine transporter belonging to the equilibrative nucleoside transporter family. Highly expressed in the brain, PMAT represents a major uptake2 transporter that may play a role in monoamine clearance. Although human PMAT has been functionally characterized at the molecular level, rodent models are often used to evaluate PMAT function in ex vivo and in vivo studies. The aim of this study was to examine if there is potential species difference in the functional characteristics of PMAT between human, rat and mouse. A set of transfected cells stably expressing human PMAT (MDCK/hPMAT), rat Pmat (MDCK/rPmat) and mouse Pmat (Flp293/mPmat) were constructed. In MDCK/hPMAT, MDCK/rPmat and Flp293/mPmat cells, cellular localization analyses revealed that hPMAT, rPmat and mPmat are expressed and mainly localized to the plasma membranes of cells. The uptake of MPP+, serotonin and dopamine by MDCK/hPMAT, MDCK/rPmat and Flp293/mPmat cells was significantly increased compared with those by the mock transfection control. In contrast, two nucleosides, uridine and adenosine, minimally interacted with PMAT/Pmat in all species. The hPMAT-, rPmat- and mPmat-mediated uptakes of MPP+, serotonin and dopamine were saturable, with Km values of 33.7 µM, 70.2 µM and 49.5 µM (MPP+),116 µM, 82.9 µM and 231 µM (serotonin), and 201 µM, 271 µM and 466 µM (dopamine), respectively, suggesting similar substrate affinities between human and rodent PMAT/Pmat. The prototypical inhibitors, decynium 22 and GBR12935, also showed similar inhibition potencies between species. In conclusion, the present study demonstrated interspecies similarities in the functional characteristics of human and rodent PMAT/Pmat, which indicate a practical utility of rat and mouse animal models for further investigating and extrapolating the in vivo function of PMAT in humans.

Comparative analysis of novel decynium-22 analogs to inhibit transport by the low-affinity, high-capacity monoamine transporters, organic cation transporters 2 and 3, and plasma membrane monoamine transporter

“…Mouse models are an essential preclinical resource to study the action of low-affinity transporters. Functional similarities have been observed between the uptake kinetics of substrates like dopamine, MPP + , and serotonin by human and mouse PMAT (Miura et al, 2017; Shirasaka et al, 2016). On the other hand, hOCT3 and mOCT3 were found to share similar affinities for MPP + , but not serotonin (Massmann et al, 2014).…”

“…Earlier work established D22 as a potent inhibitor of low-affinity/high-capacity transporters, including OCT2, OCT3, and PMAT (Gasser et al, 2009; Hayer-Zillgen, Brüss, & Bönisch, 2002; Russ, H., Gliese, Sonna, & Schömig, 1992; Russ, H. et al, 1993; Russ, H., Sonna, Keppler, Baunach, & Schömig, 1993; Russ, Hermann, Staudt, Martel, Gliese, & Schomig, 1996; Schomig, Babin-Ebell, & Russ, 1993; Shirasaka et al, 2016; Sun et al, 2014; Wang, Sun, Li, Tu, & Jiang, 2014; Zhang, Schaner, & Giacomini, 1998). In line with prior D22 action at hOCT3 (Hayer-Zillgen et al, 2002), we found that D22 was a more potent inhibitor of [ 3 H]MPP + uptake at hOCT3 (IC 50 ≈ 0.2 μM) than hOCT2 (IC 50 ≈ 10 μM) and extended this finding to hPMAT (IC 50 ≈ 1 μM).…”

Constitutive plasma membrane monoamine transporter (PMAT, Slc29a4) deficiency subtly affects anxiety‐like and coping behaviours

“…This might explain why knockout behaviour more closely resembles that of wild‐types in the elevated plus maze, whereas partial deletion of PMAT in heterozygotes might not be sufficient to elicit this compensatory upregulation and thereby could reveal a more accurate representation of constitutive PMAT deficiency. Such mice could provide valuable models of reduced PMAT function (Shirasaka et al., ), as recently two SLC29A4 polymorphisms conferring loss of function have been discovered in humans (Adamsen et al., ). Indeed, deficiency of PMAT may not become overtly evident in behaviours until monoaminergic systems are sufficiently perturbed.…”

Functional Expression of Organic Ion Transporters in Astrocytes and Their Potential as a Drug Target in the Treatment of Central Nervous System Diseases

“…73) As suggested by these reports, even though the physiological roles of OCT3 and PMAT appear to be mostly conserved among species, their inhibitor (and substrate) recognition preference must be, at least slightly, different, depending on their intrinsic amino acid sequences.…”