Metalloproteinase PAPP-A regulation of IGF-1 contributes to polycystic kidney disease pathogenesis
Sonu Kashyap, Kyaw Zaw Hein, Claudia C.S. Chini, Jorgo Lika, Gina M. Warner, Laurie K. Bale, Vicente E. Torres, Peter C. Harris, Claus Oxvig, Cheryl A. Conover, Eduardo N. Chini
Sonu Kashyap, Kyaw Zaw Hein, Claudia C.S. Chini, Jorgo Lika, Gina M. Warner, Laurie K. Bale, Vicente E. Torres, Peter C. Harris, Claus Oxvig, Cheryl A. Conover, Eduardo N. Chini
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Research Article Nephrology

Metalloproteinase PAPP-A regulation of IGF-1 contributes to polycystic kidney disease pathogenesis

Abstract

Autosomal dominant polycystic kidney disease (ADPKD) is the most common genetic cause of end-stage renal disease (ESRD). The treatment options for ADPKD are limited. We observed an upregulation in several IGF-1 pathway genes in the kidney of Pkd1RC/RC mice, a model of ADPKD. Pregnancy-associated plasma protein A (PAPP-A), a metalloproteinase that cleaves inhibitory IGF binding proteins (IGFBPs), increasing the local bioactivity of IGF-1, was highly induced in the kidney of ADPKD mice. PAPP-A levels were high in cystic fluid and kidneys of humans with ADPKD. Our studies further showed that PAPP-A transcription in ADPKD was mainly regulated through the cAMP/CREB/CBP/p300 pathway. Pappa deficiency effectively inhibited the development of cysts in the Pkd1RC/RC mice. The role of PAPP-A in cystic disease appears to be regulation of the IGF-1 pathway and cellular proliferation in the kidney. Finally, preclinical studies demonstrated that treatment with a monoclonal antibody that blocks the proteolytic activity of PAPP-A against IGFBP4 ameliorated ADPKD cystic disease in vivo in Pkd1RC/RC mice and ex vivo in embryonic kidneys. These data indicated that the PAPP-A/IGF-1 pathway plays an important role in the growth and expansion of cysts in ADPKD. Our findings introduce a therapeutic strategy for ADPKD that involves the inhibition of PAPP-A.

Authors

Sonu Kashyap, Kyaw Zaw Hein, Claudia C.S. Chini, Jorgo Lika, Gina M. Warner, Laurie K. Bale, Vicente E. Torres, Peter C. Harris, Claus Oxvig, Cheryl A. Conover, Eduardo N. Chini

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Figure 2

Molecular pathways involved in regulation of PAPP-A expression.

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Molecular pathways involved in regulation of PAPP-A expression. (A) Papp...
(A) Pappa and Igfbp4 mRNA levels in kidneys of Pkd1RC/RC (n = 4–5) and WT mice (n = 3) treated with vehicle (5% DMSO) or 5 mg/kg FSK for 24 hours at 4 weeks of age. (B and C) Pappa and Igfbp4 mRNA levels in RCTE and PKD cystic epithelial cells (9-12) treated with (B) increasing doses of FSK for 4 hours and (C) 10 μM FSK for various time intervals. (D) ELISA analysis of PAPPA levels in cell-free conditioned media of RCTE and 9-12 cells treated with 10 μM FSK or vehicle for 72 hours. (E) Proteolytic assay of PAPP-A–mediated IGFBP4 using cell-free conditioned media of RCTE and 9-12 cells treated with FSK or vehicle for 72 hours. Conditioned medium was incubated for 72 hours at 37°C with IGFBP4 without (−) or with (+) precomplexing to IGF, and without (−) or with (+) the addition of inhibitory mAb-PA 1/41 antibody. Arrows indicate intact and cleaved IGFBP4 bands. (F–I) Pappa mRNA expression in 9-12 cells treated with: (F) vehicle control (0.1% DMSO), 10 μM FSK, a selective activator of PKA (6-MB-cAMP, 200 μM) or Epac (8CPT2OMe, 30 μM) for 16 hours; (G) 10 μM FSK in the presence or absence of a competitive antagonist of cAMP (RpcAMP, 100 μM) for 16 hours; (H) 10 μM FSK in the presence or absence of the indicated doses of KG-501, which blocks cAMP-induction of CREB for 16 hours; (I) a selective CBP/p300 bromodomain inhibitor (CBP30, 10 μM) for 24 hours followed by 10 μM FSK for 16 hours. (J) Pappa mRNA expression levels in WT and Pkd1RC/RC treated with the CBP inhibitor GNE-049 (30 mg/kg, n = 5) or vehicle (Veh., n = 5) twice a day for 3 days orally. (K) Schematic representation of cAMP-induced PAPP-A expression. Data are mean ± SEM. *P < 0.05, **P < 0.01, ***P < 0.001 by 2-tailed Student’s t test or Mann Whitney U test, or 1-way ANOVA followed by Tukey’s post hoc test (for B and C, comparison of 9-12 cells is at their respective dose or time with normal cells).