Increased AQP2 targeting in primary cultured IMCD cells in response to angiotensin II through AT1 receptor.
Vasopressin and angiotensin II (ANG II) play a major role in renal water and Na(+) reabsorption. We previously demonstrated that ANG II AT(1) receptor blockade decreases dDAVP-induced water reabsorption and AQP2 levels in rats, suggesting cross talk between these two peptide hormones (Am J Physiol Renal Physiol 288: F673-F684, 2005). To directly address this issue, primary cultured inner medullary collecting duct (IMCD) cells from male Sprague-Dawley rats were treated for 15 min with 1) vehicle, 2) ANG II, 3) ANG II + the AT(1) receptor blocker candesartan, 4) dDAVP, 5) ANG II + dDAVP, or 6) ANG II + dDAVP + candesartan. Immunofluorescence microscopy revealed that 10(-8) M ANG II or 10(-11) M dDAVP (protocol 1) was associated with increased AQP2 labeling of the plasma membrane and decreased cytoplasmic labeling, respectively. cAMP levels increased significantly in response to 10(-8) M ANG II and were potentiated by cotreatment with 10(-11) M dDAVP. Consistent with this finding, immunoblotting revealed that this cotreatment significantly increased expression of phosphorylated AQP2. ANG II-induced AQP2 targeting was blocked by 10(-5) M candesartan. In protocol 2, treatment with a lower concentration of dDAVP (10(-12) M) or ANG II (10(-9) M) did not change subcellular AQP2 distribution, whereas 10(-12) M dDAVP + 10(-9) M ANG II enhanced AQP2 targeting. This effect was inhibited by cotreatment with 10(-5) M candesartan. ANG II-induced cAMP accumulation and AQP2 targeting were inhibited by inhibition of PKC activity. In conclusion, ANG II plays a role in the regulation of AQP2 targeting to the plasma membrane in IMCD cells through AT(1) receptor activation and potentiates the effect of dDAVP on AQP2 plasma membrane targeting.
Lee
Yu-Jung
YJ
Dept. of Biochemistry and Cell Biology, School of Medicine, Kyungpook National Univ., Dongin-dong 101, Taegu 700-422, Korea.
Song
In-Kyung
IK
Jang
Kyung-Jin
KJ
Nielsen
Jakob
J
Frøkiaer
Jørgen
J
Nielsen
Søren
S
Kwon
Tae-Hwan
TH
D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D051399:Aquaporin 2 / Q000187:drug effects*; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured; D003470:Culture Media; D000242:Cyclic AMP / Q000378:metabolism; D003894:Deamino Arginine Vasopressin / Q000494:pharmacology; D004357:Drug Synergism; D016259:Genes, myc / Q000235:genetics; D007150:Immunohistochemistry; D007685:Kidney Tubules, Collecting / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D009994:Osmolar Concentration; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D044140:Receptor, Angiotensin, Type 1 / Q000187:drug effects*; D012076:Renal Agents / Q000494:pharmacology; D014162:Transfection; D014508:Urea
D051399:Aquaporin 2; D003470:Culture Media; D044140:Receptor, Angiotensin, Type 1; D012076:Renal Agents; D000804:Angiotensin II; D014508:Urea; D000242:Cyclic AMP; D011493:Protein Kinase C; D003894:Deamino Arginine Vasopressin