TY - JOUR
T1 - Dehydroascorbic acid uptake and intracellular ascorbic acid accumulation in cultured Müller glial cells (TR-MUL)
AU - Hosoya, Ken ichi
AU - Nakamura, Genki
AU - Akanuma, Shin ichi
AU - Tomi, Masatoshi
AU - Tachikawa, Masanori
N1 - Funding Information:
This study was supported, in part, by a Grant-in-Aid for Scientific Research from the Japan Society for the Promotion of Science and a grant for Research on Sensory and Communicative Disorders by the Ministry of Health, Labor, and Welfare, Japan.
PY - 2008/6
Y1 - 2008/6
N2 - Vitamin C is mainly transported across the inner blood-retinal barrier (inner BRB) as dehydroascorbic acid (DHA) via a facilitative glucose transporter (GLUT) 1, and accumulates as ascorbic acid (AA) in the retina. Müller cells, huge glial cells, exhibit passive structural and metabolic functions for retinal neurons and the inner BRB. We characterized DHA transport and its corresponding transporter in a rat Müller cell line (TR-MUL5 cells). [14C]DHA uptake by TR-MUL5 cells took place in a time-dependent and Na+-independent manner. [14C]DHA uptake was inhibited by substrates and inhibitors of GLUTs, suggesting that Müller cells take up DHA via GLUTs. HPLC analysis revealed that most of the DHA taken up by TR-MUL5 cells was converted to AA and accumulated as AA in TR-MUL5 cells. [14C]DHA uptake by TR-MUL5 cells took place in a concentration-dependent manner with a Michaelis-Menten constant of 198 μM and was inhibited by cytochalasin B in a concentration-dependent manner with a 50% inhibition concentration of 0.283 μM. Although GLUT1, 3, and 4 mRNA are expressed in TR-MUL5 cells, quantitative real-time PCR revealed that GLUT1 mRNA expression was 5.85- and 116-fold greater than that of GLUT3 and 4, respectively. Western blot analysis supports the expression of GLUT1 protein with 45 kDa in TR-MUL5 cells. In conclusion, DHA is taken up by facilitative glucose transporters, most likely GLUT1, and converted to AA in TR-MUL5 cells.
AB - Vitamin C is mainly transported across the inner blood-retinal barrier (inner BRB) as dehydroascorbic acid (DHA) via a facilitative glucose transporter (GLUT) 1, and accumulates as ascorbic acid (AA) in the retina. Müller cells, huge glial cells, exhibit passive structural and metabolic functions for retinal neurons and the inner BRB. We characterized DHA transport and its corresponding transporter in a rat Müller cell line (TR-MUL5 cells). [14C]DHA uptake by TR-MUL5 cells took place in a time-dependent and Na+-independent manner. [14C]DHA uptake was inhibited by substrates and inhibitors of GLUTs, suggesting that Müller cells take up DHA via GLUTs. HPLC analysis revealed that most of the DHA taken up by TR-MUL5 cells was converted to AA and accumulated as AA in TR-MUL5 cells. [14C]DHA uptake by TR-MUL5 cells took place in a concentration-dependent manner with a Michaelis-Menten constant of 198 μM and was inhibited by cytochalasin B in a concentration-dependent manner with a 50% inhibition concentration of 0.283 μM. Although GLUT1, 3, and 4 mRNA are expressed in TR-MUL5 cells, quantitative real-time PCR revealed that GLUT1 mRNA expression was 5.85- and 116-fold greater than that of GLUT3 and 4, respectively. Western blot analysis supports the expression of GLUT1 protein with 45 kDa in TR-MUL5 cells. In conclusion, DHA is taken up by facilitative glucose transporters, most likely GLUT1, and converted to AA in TR-MUL5 cells.
KW - Dehydroascorbic acid
KW - GLUT1
KW - Inner blood-retinal barrier
KW - Müller cells
KW - Vitamin C
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U2 - 10.1016/j.neuint.2008.02.001
DO - 10.1016/j.neuint.2008.02.001
M3 - Article
C2 - 18353508
AN - SCOPUS:42149083776
SN - 0197-0186
VL - 52
SP - 1351
EP - 1357
JO - Neurochemistry International
JF - Neurochemistry International
IS - 7
ER -