Post-translational regulation of an Aplysia glutamate transporter during long-term facilitation.
Regulation of glutamate transporters accompanies plasticity of some glutamatergic synapses. The regulation of glutamate uptake at the Aplysia sensorimotor synapse during long-term facilitation (LTF) was investigated. Previously, increases in levels of ApGT1 (Aplysia glutamate transporter 1) in synaptic membranes were found to be related to long-term increases in glutamate uptake. In this study, we found that regulation of ApGT1 during LTF appears to occur post-translationally. Serotonin (5-HT) a transmitter that induces LTF did not increase synthesis of ApGT1. A pool of ApGT1 appears to exist in sensory neuron somata, which is transported to the terminals by axonal transport. Blocking the rough endoplasmic reticulum-Golgi-trans-Golgi network (TGN) pathway with Brefeldin A prevented the 5-HT-induced increase of ApGT1 in terminals. Also, 5-HT produced changes in post-translational modifications of ApGT1 as well as changes in the levels of an ApGT1-co-precipitating protein. These results suggest that regulation of trafficking of ApGT1 from the vesicular trafficking system (rough endoplasmic reticulum-Golgi-TGN) in the sensory neuron somata to the terminals by post-translational modifications and protein interactions appears to be the mechanism underlying the increase in ApGT1, and thus, glutamate uptake during memory formation.
Collado
Maria Sol
MS
Department of Biology & Biochemistry, University of Houston, Science and Research II, Houston, Texas 77204-5001, USA.
Khabour
Omar
O
Fioravante
Diasinou
D
Byrne
John H
JH
Eskin
Arnold
A
D000818:Animals; D001048:Aplysia; D020126:Brefeldin A / Q000494:pharmacology; D002478:Cells, Cultured; D003078:Colchicine / Q000494:pharmacology; D004558:Electric Stimulation; D027342:Excitatory Amino Acid Transporter 2 / Q000235:genetics / Q000378:metabolism*; D017952:Ganglia, Invertebrate / Q000166:cytology; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D018698:Glutamic Acid / Q000378:metabolism; D017774:Long-Term Potentiation / Q000187:drug effects / Q000502:physiology*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D011984:Sensory Receptor Cells / Q000187:drug effects / Q000502:physiology*; D012701:Serotonin / Q000494:pharmacology; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism; D013997:Time Factors
D027342:Excitatory Amino Acid Transporter 2; D011500:Protein Synthesis Inhibitors; D020126:Brefeldin A; D012701:Serotonin; D018698:Glutamic Acid; D003078:Colchicine