Human Molecular Genetics Advance Access published online on April 3, 2009
Human Molecular Genetics, doi:10.1093/hmg/ddp165
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Systems Biology of Autosomal Dominant Polycystic Kidney Disease (ADPKD): Computational Identification of Gene Expression Pathways and Integrated Regulatory Networks
1 Division of Nephrology, University Health Network and University of Toronto, Toronto, Ontario, Canada 2 Program in Developmental and Stem Cell Biology, Hospital for Sick Children and University of Toronto, Toronto, Ontario, Canada 3 Division of Nephrology, McMaster University, Hamilton, Ontario, Canada
Address correspondence to: York Pei, MD, FRCP(C) Division of Nephrology, University Health Network, 8N838, 585 University Avenue, Toronto, Ontario, Canada M5G 2N2, Canada Tel: 416-340-4257 Fax: 416-340-4999 E-mail: York.Pei{at}uhn.on.ca
Received February 23, 2009; Revised April 1, 2009; Accepted April 1, 2009
To elucidate the molecular pathways that modulate renal cyst growth in ADPKD, we performed global gene profiling on cysts of different size (<1 ml, n=5; 10-20 ml, n=5; >50 ml, n=3) and minimally cystic tissue (MCT, n=5) from five PKD1 human polycystic kidneys using Affymetrix HG-U133 Plus 2.0 arrays. We used Gene Set Enrichment Analysis to identify overrepresented signaling pathways and key transcription factors (TFs) between cysts and MCT. We found down-regulation of kidney epithelial restricted genes (e.g. nephron segment-specific markers and cilia-associated cystic genes such as HNF1B, PKHD1, IFT88 and CYS1) in the renal cysts. On the other hand, PKD1 cysts displayed a rich profile of gene sets associated with renal development, mitogen-mediated proliferation, cell cycle progression, epithelial-mesenchymal transition, hypoxia, aging, and immune/inflammatory responses. Notably, our data suggest that up-regulation of Wnt/beta-catenin, pleiotropic growth factor/receptor tyrosine kinase (e.g. IGF/IGF1R, FGF/FGFR, EGF/EGFR, VEGF/VEGFR), G-protein-coupled receptor (e.g. PTGER2) signaling was associated with renal cystic growth. By integrating these pathways with a number of dysregulated networks of TFs (e.g. SRF, MYC, E2F1, CREB1, LEF1, TCF7, HNF1B/ HNF1A, and HNF4A), our data suggest that epithelial dedifferentiation accompanied by aberrant activation and cross-talk of specific signaling pathways may be required for PKD1 cyst growth and disease progression. Pharmacological modulation of some of these signaling pathways may provide a potential therapeutic strategy for ADPKD.