title: Molecular mechanisms of angiotensin II stimulation on aquaporin-2 expression and trafficking.
abstract: ANG II plays a major role in renal water and sodium regulation. In the immortalized mouse renal collecting duct principal cells (mpkCCD(cl4)) cell line, we treated cells with ANG II and examined aquaporin-2 (AQP2) protein expression, trafficking, and mRNA levels, by immunoblotting, immunofluorescence, and RT-PCR. After 24-h incubation, ANG II-induced AQP2 protein expression was observed at the concentration of 10(-10) M and increased in a dose-dependent manner. ANG II (10(-7) M) increased AQP2 protein expression and mRNA levels at 0.5, 1, 2, 6, and 24 h. Immunofluorescence studies showed that ANG II increased the apical membrane targeting of AQP2 from 30 min to 6 h. Next, the signaling pathways underlying the ANG II-induced AQP2 expression were investigated. The PKC inhibitor Ro 31-8220 (5 × 10(-6) M) and the PKA inhibitor H89 (10(-5) M) blocked ANG II-induced AQP2 expression, respectively. Calmodulin inhibitor W-7 markedly reduced ANG II- and/or dDAVP-stimulated AQP2 expression. ANG II (10(-9) M) and/or dDAVP (10(-10) M) stimulated AQP2 protein levels and cAMP accumulation, which was completely blocked by pretreatment with the vasopressin V2 receptor (V2R) antagonist SR121463B (10(-8) M). Pretreatment with the angiotensin AT(1) receptor (AT1R) antagonist losartan (3 × 10(-6) M) blocked ANG II (10(-9) M)-stimulated AQP2 protein expression and cAMP accumulation, and partially blocked dDAVP (10(-10) M)- and dDAVP+ANG II-induced AQP2 protein expression and cAMP accumulation. In conclusion, ANG II regulates AQP2 protein, trafficking, and gene expression in renal collecting duct principal cells. ANG II-induced AQP2 expression involves cAMP, PKC, PKA, and calmodulin signaling pathways via V2 and AT(1) receptors.
authors.affiliation: Department of Medicine, University of Colorado Health Sciences Center, Aurora, Colorado, USA.
authors.forename: Chunling
authors.initials: C
authors.lastname: Li
authors.forename: Weidong
authors.initials: W
authors.lastname: Wang
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Rivard
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Lanaspa
authors.forename: Sandra
authors.initials: S
authors.lastname: Summer
authors.forename: Robert W
authors.initials: RW
authors.lastname: Schrier
mesh_terms: D000704:Analysis of Variance; D000804:Angiotensin II / Q000378:metabolism*; D047228:Angiotensin II Type 1 Receptor Blockers / Q000494:pharmacology; D000818:Animals; D051399:Aquaporin 2 / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western; D002147:Calmodulin / Q000378:metabolism; D002460:Cell Line; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D003894:Deamino Arginine Vasopressin / Q000494:pharmacology; D005455:Fluorescent Antibody Technique; D006727:Hormone Antagonists / Q000494:pharmacology; D007685:Kidney Tubules, Collecting / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D011493:Protein Kinase C / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D021381:Protein Transport; D012333:RNA, Messenger / Q000378:metabolism; D044140:Receptor, Angiotensin, Type 1 / Q000378:metabolism; D017483:Receptors, Vasopressin / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors
chemical_list: D047228:Angiotensin II Type 1 Receptor Blockers; C496024:Aqp2 protein, mouse; D051399:Aquaporin 2; D002147:Calmodulin; D006727:Hormone Antagonists; D047428:Protein Kinase Inhibitors; D012333:RNA, Messenger; D044140:Receptor, Angiotensin, Type 1; D017483:Receptors, Vasopressin; D000804:Angiotensin II; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D003894:Deamino Arginine Vasopressin