Predominant role of plasma membrane monoamine transporters in monoamine transport in 1321N1, a human astrocytoma-derived cell line.
Monoamine neurotransmitters should be immediately removed from the synaptic cleft to avoid excessive neuronal activity. Recent studies have shown that astrocytes and neurons are involved in monoamine removal. However, the mechanism of monoamine transport by astrocytes is not entirely clear. We aimed to elucidate the transporters responsible for monoamine transport in 1321N1, a human astrocytoma-derived cell line. First, we confirmed that 1321N1 cells transported dopamine, serotonin, norepinephrine, and histamine in a time- and dose-dependent manner. Kinetics analysis suggested the involvement of low-affinity monoamine transporters, such as organic cation transporter (OCT) 2 and 3 and plasma membrane monoamine transporter (PMAT). Monoamine transport in 1321N1 cells was not Na(+) /Cl(-) dependent but was inhibited by decynium-22, an inhibitor of low-affinity monoamine transporters, which supported the importance of low-affinity transporters. RT-PCR assays revealed that 1321N1 cells expressed OCT3 and PMAT but no other neurotransmitter transporters. Another human astrocytoma-derived cell line, U251MG, and primary human astrocytes also exhibited the same gene expression pattern. Gene-knockdown assays revealed that 1321N1 and primary human astrocytes could transport monoamines predominantly through PMAT and partly through OCT3. These results might indicate that PMAT and OCT3 in human astrocytes are involved in monoamine clearance.
Department of Pharmacology, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan.
Fumito
F
Naganuma
Takeo
T
Yoshikawa
Tadaho
T
Nakamura
Tomomitsu
T
Iida
Ryuichi
R
Harada
Attayeb S
AS
Mohsen
Yamato
Y
Miura
Kazuhiko
K
Yanai
D001253:Astrocytes / Q000378:metabolism*; D001254:Astrocytoma / Q000473:pathology; D015306:Biogenic Monoamines / Q000378:metabolism*; D001692:Biological Transport; D045744:Cell Line, Tumor; D033705:Equilibrative Nucleoside Transport Proteins / Q000378:metabolism*; D020869:Gene Expression Profiling; D006706:Homeostasis; D006801:Humans; D008954:Models, Biological; D027701:Organic Cation Transport Proteins / Q000378:metabolism*; D034622:RNA Interference; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000099254:Organic Cation Transporter 3
D015306:Biogenic Monoamines; D033705:Equilibrative Nucleoside Transport Proteins; D027701:Organic Cation Transport Proteins; D000099254:Organic Cation Transporter 3; C495988:SLC29A4 protein, human
astrocytes; low-affinity transporters; monoamine neurotransmitters; organic cation transporter; plasma membrane monoamine transporter