Phosphodiesterase Isoform Regulation of Cell Proliferation and Fluid Secretion in Autosomal Dominant Polycystic Kidney Disease

Abstract

cAMP stimulates cell proliferation and Cl--dependent fluid secretion, promoting the progressive enlargement of renal cysts in autosomal dominant polycystic kidney disease (ADPKD). Intracellular cAMP levels are determined by the balance of cAMP synthesis by adenylyl cyclases and degradation by phosphodiesterases (PDEs). Therefore, PDE isoform expression and activity strongly influence global and compartmentalized cAMP levels. We report here that PDE3 and PDE4 expression levels are lower in human ADPKD tissue and cells compared with those of normal human kidneys (NHKs), whereas PDE1 levels are not significantly different. Inhibition of PDE4 caused a greater increase in basal and vasopressin (AVP)-stimulated cAMP levels and Cl -secretion by ADPKD cells than inhibition of PDE1, and inhibition of PDE4 induced cyst-like dilations in cultured mouse Pkd1 2/2 embryonic kidneys. In contrast, inhibition of PDE1 caused greater stimulation of extracellular signal-regulated kinase (ERK) and proliferation of ADPKD cells than inhibition of PDE4, and inhibition of PDE1 enhanced AVP-induced ERK activation. Notably, inhibition of PDE1, the only family of Ca 2+-regulated PDEs, also induced a mitogenic response to AVP in NHK cells, similar to the effect of restricting intracellular Ca 2+. PDE1 coimmunoprecipitated with B-Raf and A-kinase anchoring protein 79, and AVP increased this interaction in ADPKD but not NHK cells. These data suggest that whereas PDE4 is the major PDE isoform involved in the regulation of global intracellular cAMP and Cl -secretion, PDE1 specifically affects the cAMP signal to the B-Raf/MEK/ERK pathway and regulates AVP-induced proliferation of ADPKD cells.

Lysine methyltransferase SMYD2 promotes cyst growth in autosomal dominant polycystic kidney disease

“…human ADPKD and NHK cells were provided by the PKD Research Biomaterials and Cellular Models Core at the University of Kansas Medical Center (KUMC) and were cultured as described previously (42,53). AZ505 was purchased from MedChem Express and dissolved in DMSO (Sigma-Aldrich) at a stock solution of 20 mM.…”

Deficient transient receptor potential vanilloid type 4 function contributes to compromised [Ca2+] homeostasis in human autosomal‐dominant polycystic kidney disease cells

“…In contrast, an elevation of [Ca 2+ ] i in ADPKD cells restores the normal anti-mitogenic response to cAMP by preventing the activation of B-Raf and ERK (11). Consequently, inhibiting the cAMP-dependent pathways, such as arginine vasopressin type 2 receptor blockade with tolvaptan, or tweaking mechanisms that control cAMP metabolism, such as inhibition of adenylyl cyclases or stimulation of phosphodiesterases, demonstrate notable anticystogenic effects in both basic and clinical studies (17,(50)(51)(52); however, interference with cAMP-dependent renal water reabsorption as a result of continuous tolvaptan administration is associated with undesired adverse effects, including polyuria, dehydration, and thirst in patients with PKD, which often leads to the discontinuation of treatment (51). In this regard, stimulation of TRPV4 could be an alternative strategy to counteract cAMP-dependent proliferation and cyst growth.…”

Integrin-Linked Kinase Signaling Promotes Cyst Growth and Fibrosis in Polycystic Kidney Disease

“…Primary cell cultures were prepared as described previously. 69,70 Cells were propagated in DMEM/F12 supplemented with 5% FBS, 5 mg/ml insulin, 5 mg/ml transferrin, and 5 ng/ml sodium selenite (ITS) and penicillin G and streptomycin (P/S). After cells had reached 70%-80% confluence in the flasks, they were lifted from the plastic with a trypsin-EDTA solution (Sigma Chemical, Saint Louis, MO) and counted using a hemocytometer.…”