Deficiency of polycystic kidney disease-1 gene (PKD1) expression increases A(3) adenosine receptors in human renal cells: implications for cAMP-dependent signalling and proliferation of PKD1-mutated cystic cells.
Cyst growth and expansion in autosomal dominant polycystic kidney disease (ADPKD) has been attributed to numerous factors, including ATP, cAMP and adenosine signalling. Although the role of ATP and cAMP has been widely investigated in PKD1-deficient cells, no information is currently available on adenosine-mediated signalling. Here we investigate for the first time the impact of abnormalities of polycystin-1 (PC1) on the expression and functional activity of adenosine receptors, members of the G-protein-coupled receptor superfamily. Pharmacological, molecular and biochemical findings show that a siRNA-dependent PC1-depletion in HEK293 cells and a PKD1-nonsense mutation in cyst-derived cell lines result in increased expression of the A(3) adenosine receptor via an NFkB-dependent mechanism. Interestingly, A(3) adenosine receptor levels result higher in ADPKD than in normal renal tissues. Furthermore, the stimulation of this receptor subtype with the selective agonist Cl-IB-MECA causes a reduction in both cytosolic cAMP and cell proliferation in both PC1-deficient HEK293 cells and cystic cells. This reduction is associated with increased expression of p21(waf) and reduced activation not only of ERK1/2, but also of S6 kinase, the main target of mTOR signalling. In the light of these findings, the ability of Cl-IB-MECA to reduce disease progression in ADPKD should be further investigated. Moreover, our results suggest that NFkB, which is markedly activated in PC1-deficient and cystic cells, plays an important role in modulating A(3)AR expression in cystic cells.
Aguiari
Gianluca
G
Department of Biochemistry and Molecular Biology, Section of Molecular Biology, University of Ferrara, Italy.
Varani
Katia
K
Bogo
Marco
M
Mangolini
Alessandra
A
Vincenzi
Fabrizio
F
Durante
Chiara
C
Gessi
Stefania
S
Sacchetto
Valeria
V
Catizone
Luigi
L
Harris
Peter
P
Rizzuto
Rosario
R
Borea
Pier Andrea
PA
Del Senno
Laura
L
D000255:Adenosine Triphosphate / Q000378:metabolism*; D002460:Cell Line; D049109:Cell Proliferation; D015870:Gene Expression; D006801:Humans; D007668:Kidney / Q000378:metabolism*; D007684:Kidney Tubules / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D009154:Mutation; D043684:Receptor, Adenosine A3 / Q000378:metabolism*; D019893:Ribosomal Protein S6 Kinases / Q000378:metabolism; D015398:Signal Transduction; D050396:TRPP Cation Channels / Q000235:genetics* / Q000378:metabolism*
D000255:Adenosine Triphosphate; D048052:Mitogen-Activated Protein Kinase 3; D043684:Receptor, Adenosine A3; D019893:Ribosomal Protein S6 Kinases; D050396:TRPP Cation Channels