TY - JOUR
T1 - The methylmercury-L-cysteine conjugate is a substrate for the L-type large neutral amino acid transporter
AU - Yin, Zhaobao
AU - Jiang, Haiyan
AU - Syversen, Tore
AU - Rocha, João B.T.
AU - Farina, Marcelo
AU - Aschner, Michael
PY - 2008/11
Y1 - 2008/11
N2 - Methylmercury (MeHg) is a potent neurotoxin. The mechanism(s) that governs MeHg transport across the blood-brain barrier and other biological membranes remains unclear. This study addressed the role of the L-type large neutral amino acid transporter, LAT1, in MeHg transport. Studies were carried out in CHO-k1 cells. Over-expression of LAT1 in these cells was associated with enhanced uptake of [14C]-MeHg when treated with l-cysteine, but not with the d-cysteine conjugate. In the presence of excess l-methionine, a substrate for LAT1, l-cysteine-conjugated [14C]-MeHg uptake was significantly attenuated. Treatment of LAT-1 over-expressing CHO-k1 cells with l-cysteine-conjugated MeHg was also associated with increased leakage of lactate dehydrogenase into the media as well as reduced cell viability measured by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide reduction assay. In contrast, knock-down of LAT1 decreased the uptake of l-cysteine-conjugated MeHg and attenuated the effects of MeHg on lactate dehydrogenase leakage and CHO-k1 cell viability. These results indicate that the MeHg-l-cysteine conjugate is a substrate for the neutral amino acid transporter, LAT1, which actively transports MeHg across membranes.
AB - Methylmercury (MeHg) is a potent neurotoxin. The mechanism(s) that governs MeHg transport across the blood-brain barrier and other biological membranes remains unclear. This study addressed the role of the L-type large neutral amino acid transporter, LAT1, in MeHg transport. Studies were carried out in CHO-k1 cells. Over-expression of LAT1 in these cells was associated with enhanced uptake of [14C]-MeHg when treated with l-cysteine, but not with the d-cysteine conjugate. In the presence of excess l-methionine, a substrate for LAT1, l-cysteine-conjugated [14C]-MeHg uptake was significantly attenuated. Treatment of LAT-1 over-expressing CHO-k1 cells with l-cysteine-conjugated MeHg was also associated with increased leakage of lactate dehydrogenase into the media as well as reduced cell viability measured by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide reduction assay. In contrast, knock-down of LAT1 decreased the uptake of l-cysteine-conjugated MeHg and attenuated the effects of MeHg on lactate dehydrogenase leakage and CHO-k1 cell viability. These results indicate that the MeHg-l-cysteine conjugate is a substrate for the neutral amino acid transporter, LAT1, which actively transports MeHg across membranes.
KW - Amino acid transport
KW - L-type large neutral amino acid transporter
KW - Methylmercury
KW - Neurotoxicity
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U2 - 10.1111/j.1471-4159.2008.05683.x
DO - 10.1111/j.1471-4159.2008.05683.x
M3 - Article
C2 - 18793329
AN - SCOPUS:84984577326
SN - 0022-3042
VL - 107
SP - 1083
EP - 1090
JO - Journal of Neurochemistry
JF - Journal of Neurochemistry
IS - 4
ER -