Par-4 inhibits choline uptake by interacting with CHT1 and reducing its incorporation on the plasma membrane.

CHT1 is a Na(+)- and Cl(-)-dependent, hemicholinium-3 (HC-3)-sensitive, high affinity choline transporter. Par-4 (prostate apoptosis response-4) is a leucine zipper protein involved in neuronal degeneration and cholinergic signaling in Alzheimer's disease. We now report that Par-4 is a negative regulator of CHT1 choline uptake activity. Transfection of neural IMR-32 cells ...
with human CHT1 conferred Na(+)-dependent, HC-3-sensitive choline uptake that was effectively inhibited by cotransfection of Par-4. Mapping studies indicated that the C-terminal half of Par-4 was physically involved in interacting with CHT1, and the absence of Par-4.CHT1 complex formation precluded the loss of CHT1-mediated choline uptake induced by Par-4, indicating that Par-4.CHT1 complex formation is essential. Kinetic and cell-surface biotinylation assays showed that Par-4 inhibited CHT1-mediated choline uptake by reducing CHT1 expression in the plasma membrane without significantly altering the affinity of CHT1 for choline or HC-3. These results suggest that Par-4 is directly involved in regulating choline uptake by interacting with CHT1 and by reducing its incorporation on the cell surface.
Mesh Terms:
Animals, Apoptosis Regulatory Proteins, Biotinylation, Blotting, Western, Carrier Proteins, Cell Death, Cell Line, Tumor, Cell Membrane, Cells, Cultured, Choline, Cholinergic Agents, DNA, Complementary, Dose-Response Relationship, Drug, Hemicholinium 3, Hippocampus, Humans, Immunohistochemistry, Intracellular Signaling Peptides and Proteins, Kinetics, Membrane Transport Proteins, Mice, Microscopy, Confocal, Neuroblastoma, Neurons, Phenotype, Precipitin Tests, Prosencephalon, Protein Binding, Protein Structure, Tertiary, Transfection
J. Biol. Chem.
Date: Jul. 02, 2004
Download Curated Data For This Publication
12642
Switch View:
  • Interactions 4