Sodium-dependent glutamate transport in Müller glial cells: regulation by phorbol esters.
The regulation of the Na(+)-dependent high affinity glutamate/aspartate transporter system expressed in cultured Müller glia cells from chick retina was studied. Treatment of the cells with the Ca(2+)/diacylglycerol dependent protein kinase C (PKC) activator, phorbol 12-tetradecanoil-13-acetate (TPA) produced a decrease in [(3)H]D-aspartate uptake which was reversed by staurosporine and partially by H7 [1-(5-isoquinolinesulfonyl)-2-methylpiperazine dihydrochoride], two PKC inhibitors. Long-term treatment with TPA resulted in a drastic decrease in the uptake activity, correlated with a substantial fall in the expression of the transporter protein. These findings suggest that PKC is involved in transport modulation at two different levels: phosphorylation and transporter expression in retinal Müller glial cells.
Departamento de Genética y Biología Molecular, CINVESTAV-IPN, Apartado Postal 14-740, México D.F. 07000, Mexico.
M I
MI
González
A M
AM
López-Colom
A
A
Ortega
D018528:ATP-Binding Cassette Transporters / Q000187:drug effects*; D027322:Amino Acid Transport System X-AG; D000818:Animals; D002478:Cells, Cultured; D002642:Chick Embryo; D004789:Enzyme Activation; D009457:Neuroglia / Q000187:drug effects* / Q000378:metabolism; D011493:Protein Kinase C / Q000187:drug effects; D012160:Retina / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*
D018528:ATP-Binding Cassette Transporters; D027322:Amino Acid Transport System X-AG; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate