Protein kinase A-dependent phosphorylation of aquaporin-1.
The molecular mechanisms for regulating water balance in many tissues are unknown. Like the kidney, the eye contains multiple water channel proteins (aquaporins) that transport water through membranes, including two (AQP1 and AQP4) in the ciliary body, the site of aqueous humor production. Previous results from our laboratory demonstrated that water channel activity of AQP1 was significantly increased by protein kinase A (PKA) activators such as cyclic-AMP (cAMP) and forskolin. The purpose of this study is to determine whether PKA-dependent protein phosphorylation is involved in the regulation of water channel activity of AQP1. Results presented here suggest that catalytic subunit of protein kinase A significantly increased the amount of phosphorylated AQP1 protein. In addition, these results indicated that cAMP-responsive redistribution of AQP1 may be regulated by phosphorylation of AQP1. Moreover, they provide new insights on the molecular mechanisms for regulating water balance in several tissues involving rapid water transport such as ciliary epithelium. In addition, they suggest important potential roles for AQP1 in several clinical disorders involving rapid water transport such as glaucoma.
Han
Z
Z
Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Patil
R V
RV
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D051398:Aquaporin 1; D020346:Aquaporins / Q000737:chemistry / Q000378:metabolism*; D001127:Arginine Vasopressin / Q000494:pharmacology; D001692:Biological Transport / Q000187:drug effects; D020134:Catalytic Domain; D002457:Cell Extracts; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D000242:Cyclic AMP / Q000031:analogs & derivatives / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology*; D003593:Cytoplasm / Q000187:drug effects / Q000378:metabolism; D006031:Glycosylation; D007668:Kidney / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D008970:Molecular Weight; D009865:Oocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D010750:Phosphoproteins / Q000737:chemistry / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D051381:Rats; D014982:Xenopus laevis
C496022:Aqp1 protein, rat; D020346:Aquaporins; D002457:Cell Extracts; D010750:Phosphoproteins; D001127:Arginine Vasopressin; D051398:Aquaporin 1; D015124:8-Bromo Cyclic Adenosine Monophosphate; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases