Protein kinase C restricts transport of carnitine by amino acid transporter ATB(0,+) apically localized in the blood-brain barrier.
Carnitine (3-hydroxy-4-trimethylammoniobutyrate) is necessary for transfer of fatty acids through the inner mitochondrial membrane. Carnitine, not synthesized in the brain, is delivered there through the strongly polarized blood-brain barrier (BBB). Expression and presence of two carnitine transporters - organic cation/carnitine transporter (OCTN2) and amino acid transporter B(0,+) (ATB(0,+)) have been demonstrated previously in an in vitro model of the BBB. Due to potential protein kinase C (PKC) phosphorylation sites within ATB(0,+) sequence, the present study verified effects of this kinase on transporter function and localization in the BBB. ATB(0,+) can be regulated by estrogen receptor α and up-regulated in vitro, therefore its presence in vivo was verified with the transmission electron microscopy. The analyses of brain slices demonstrated ATB(0,+) luminal localization in brain capillaries, confirmed by biotinylation experiments in an in vitro model of the BBB. Brain capillary endothelial cells were shown to control carnitine gradient. ATB(0,+) was phosphorylated by PKC, what correlated with inhibition of carnitine transport. PKC activation did not change the amount of ATB(0,+) present in the apical membrane of brain endothelial cells, but resulted in transporter exclusion from raft microdomains. ATB(0,+) inactivation by a lateral movement in plasma membrane after transporter phosphorylation has been postulated.
Laboratory of Mechanisms of Transport Through Biomembranes, Nencki Institute of Experimental Biology, Warsaw, Poland.
Katarzyna
K
Michalec
Univ Lille Nord de France, Lille, France; UArtois, LBHE, Lens, France; IMPRT-IFR114, Lille, France.
Caroline
C
Mysiorek
Univ Lille Nord de France, Lille, France; UArtois, LBHE, Lens, France; IMPRT-IFR114, Lille, France.
Mélanie
M
Kuntz
Univ Lille Nord de France, Lille, France; UArtois, LBHE, Lens, France; IMPRT-IFR114, Lille, France.
Vincent
V
Bérézowski
Laboratory of Molecular and Systemic Neuromorphology, Nencki Institute of Experimental Biology, Warsaw, Poland.
Andrzej A
AA
Szczepankiewicz
Laboratory of Molecular and Systemic Neuromorphology, Nencki Institute of Experimental Biology, Warsaw, Poland.
Grzegorz M
GM
Wilczyński
Univ Lille Nord de France, Lille, France; UArtois, LBHE, Lens, France; IMPRT-IFR114, Lille, France.
Roméo
R
Cecchelli
Laboratory of Mechanisms of Transport Through Biomembranes, Nencki Institute of Experimental Biology, Warsaw, Poland. Electronic address: k.nalecz@nencki.gov.pl.
Katarzyna A
KA
Nałęcz
D000818:Animals; D001693:Biological Transport, Active; D001812:Blood-Brain Barrier / Q000378:metabolism*; D001921:Brain / Q000098:blood supply / Q000378:metabolism / Q000648:ultrastructure; D002331:Carnitine / Q000378:metabolism*; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism; D008297:Male; D021962:Membrane Microdomains / Q000378:metabolism; D046529:Microscopy, Electron, Transmission; D008959:Models, Neurological; D050479:Neurotransmitter Transport Proteins / Q000378:metabolism*; D027701:Organic Cation Transport Proteins / Q000378:metabolism; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D000074058:Solute Carrier Family 22 Member 5; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D050479:Neurotransmitter Transport Proteins; D027701:Organic Cation Transport Proteins; C115441:Slc22a5 protein, rat; C515774:Slc6a14 protein, rat; D000074058:Solute Carrier Family 22 Member 5; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate; D002331:Carnitine
Amino acid transporter (ATB(0,+)); Blood–brain barrier; Organic cation transporter (OCTN2); Protein kinase C; l-Carnitine