Water permeability of aquaporin-4 is decreased by protein kinase C and dopamine

• Published in: American Journal of Physiology - Renal Physiology 2002-08, Vol.283 (2), p.F309-F318
• Main Authors: Zelenina, Marina, Zelenin, Sergey, Bondar, Alexander A, Brismar, Hjalmar, Aperia, Anita
• Format: Article
• Language: English
• Subjects: Animals; Aquaporin 4; Aquaporins - chemistry; Aquaporins - genetics; Aquaporins - metabolism; arginine-vasopressin; Biological Transport - drug effects; Biological Transport - physiology; Carcinogens - pharmacology; channel homologs; cortical collecting tubule; Dopamine - pharmacology; green fluorescent protein; Green Fluorescent Proteins; Indicators and Reagents - metabolism; kidney-cells; LLC-PK1 Cells; Luminescent Proteins - genetics; Medicin och hälsovetenskap; membrane domains; messenger-rna; molecular-biology; muller cells; Mutagenesis, Site-Directed - physiology; Phorbol 12,13-Dibutyrate - pharmacology; Phosphorylation; Protein Kinase C - metabolism; protein kinase C phosphorylation; Protein Structure, Tertiary; rat-brain; Serine - genetics; skeletal-muscle; Swine; Transfection; Water - metabolism; water channels; water transport
• ISSN: 1931-857X; 0363-6127; 1522-1466; 1522-1466
• DOI: 10.1152/ajprenal.00260.2001

Aquaporin-4 (AQP4) plays an important role in the basolateral movement of water in the collecting duct. Here we show that this water channel can be dynamically regulated. Water permeability (P(f)) was measured in individual LLC-PK1 cells that were transiently transfected with AQP4. To identify which cells were transfected, AQP4 was tagged at the NH2 terminus with green fluorescent protein. Transfected cells showed a strong fluorescent signal in basolateral membrane and a low-to-negligible signal in the cytosol and apical membrane. Activation of protein kinase C (PKC) with phorbol 12,13-dibutyrate (PDBu) significantly decreased P(f) of cells expressing AQP4 but had no effect on neighboring untransfected cells. No redistribution of AQP4 in response to PDBu was detected. Dopamine also decreased the P(f) in transfected cells. The effect was abolished by the PKC inhibitor Ro 31-8220. Reduction of AQP4 water permeability by PDBu and dopamine was abolished by point mutation of Ser(180), a consensus site for PKC phosphorylation. We conclude that PKC and dopamine decrease AQP4 water permeability via phosphorylation at Ser180 and that the effect is likely mediated by gating of the channel.