Functional expression of choline transporter like-protein 1 (CTL1) and CTL2 in human brain microvascular endothelial cells.

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Iwao B, Yara M, Hara N, Kawai Y, Yamanaka T, Nishihara H, Inoue T, Inazu M

Functional expression of choline transporter like-protein 1 (CTL1) and CTL2 in human brain microvascular endothelial cells.

Neurochem Int. 2016 Feb;93:40-50. doi: 10.1016/j.neuint.2015.12.011. Epub 2015 Dec 31.

PubMed ID

26746385 [ View in PubMed

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Abstract

In this study, we examined the molecular and functional characterization of choline transporter in human brain microvascular endothelial cells (hBMECs). Choline uptake into hBMECs was a saturable process that was mediated by a Na(+)-independent, membrane potential and pH-dependent transport system. The cells have two different [(3)H]choline transport systems with Km values of 35.0 +/- 4.9 muM and 54.1 +/- 8.1 muM, respectively. Choline uptake was inhibited by choline, acetylcholine (ACh) and the choline analog hemicholinium-3 (HC-3). Various organic cations also interacted with the choline transport system. Choline transporter-like protein 1 (CTL1) and CTL2 mRNA were highly expressed, while mRNA for high-affinity choline transporter 1 (CHT1) and organic cation transporters (OCTs) were not expressed in hBMECs. CTL1 and CTL2 proteins were localized to brain microvascular endothelial cells in human brain cortical sections. Both CTL1 and CTL2 proteins were expressed on the plasma membrane and mitochondria. CTL1 and CTL2 proteins are mainly expressed in plasma membrane and mitochondria, respectively. We conclude that choline is mainly transported via an intermediate-affinity choline transport system, CTL1 and CTL2, in hBMECs. These transporters are responsible for the uptake of extracellular choline and organic cations. CTL2 participate in choline transport mainly in mitochondria, and may be the major site for the control of choline oxidation.

DrugBank Data that Cites this Article

Drug Transporters

Drug	Transporter	Kind	Organism	Pharmacological Action	Actions
Choline	Choline transporter-like protein 2	Protein	Humans	Unknown	Substrate	Details