Cyst formation in the PKD2 (1-703) transgenic rat precedes deregulation of proliferation-related pathways

BackgroundPolycystic Kidney Disease is characterized by the formation of large fluid-filled cysts that eventually destroy the renal parenchyma leading to end-stage renal failure. Although remarkable progress has been made in understanding the pathologic mechanism of the disease, the precise orchestration of the early events leading to cyst formation is still unclear. Abnormal cellular proliferation was traditionally considered to be one of the primary irregularities leading to cyst initiation and growth. Consequently, many therapeutic interventions have focused on targeting this abnormal proliferation, and some have even progressed to clinical trials. However, the role of proliferation in cyst development was primarily examined at stages where cysts are already visible in the kidneys and therefore at later stages of disease development.MethodsIn this study we focused on the cystic phenotype since birth in an attempt to clarify the temporal contribution of cellular proliferation in cyst development. Using a PKD2 transgenic rat model (PKD2 (1-703)) of different ages (0-60 days after birth) we performed gene expression profiling and phenotype analysis by measuring various kidney parameters.ResultsPhenotype analysis demonstrated that renal cysts appear immediately after birth in the PKD2 transgenic rat model (PKD2 (1-703)). On the other hand, abnormal proliferation occurs at later stages of the disease as identified by gene expression profiling. Interestingly, other pathways appear to be deregulated at early stages of the disease in this PKD model. Specifically, gene expression analysis demonstrated that at day 0 the RAS system is involved. This is altered at day 6, when Wnt signaling and focal adhesion pathways are affected. However, at and after 24 days, proliferation, apoptosis, altered ECM signaling and many other factors become involved.ConclusionsOur data suggest that cystogenesis precedes deregulation of proliferation-related pathways, suggesting that proliferation abnormalities may contribute in cyst growth rather than cyst formation.

[1]  V. D’Agati,et al.  Dysregulation of cellular proliferation and apoptosis mediates human autosomal dominant polycystic kidney disease (ADPKD). , 1996, Oncogene.

[2]  P. George-Hyslop,et al.  Mutations of PKD1 in ADPKD2 cysts suggest a pathogenic effect of trans-heterozygous mutations , 2000, Nature Genetics.

[3]  J. Harding,et al.  Angiotensin IV AT4-receptor system in the rat kidney. , 1998, American journal of physiology. Renal physiology.

[4]  G. Germino,et al.  Polycystin-1, the gene product of PKD1, induces resistance to apoptosis and spontaneous tubulogenesis in MDCK cells. , 2000, Molecular cell.

[5]  K. Eckardt,et al.  Expression of hypoxia-inducible transcription factors in developing human and rat kidneys. , 2006, Kidney international.

[6]  Y. Tao,et al.  Rapamycin markedly slows disease progression in a rat model of polycystic kidney disease. , 2004, Journal of the American Society of Nephrology : JASN.

[7]  Meguid El Nahas,et al.  Haploinsufficiency of Pkd2 is associated with increased tubular cell proliferation and interstitial fibrosis in two murine Pkd2 models. , 2006, Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association.

[8]  Xiaogang Li,et al.  Polycystin-1 and polycystin-2 regulate the cell cycle through the helix–loop–helix inhibitor Id2 , 2005, Nature Cell Biology.

[9]  A. Pierides,et al.  Loss of heterozygosity in polycystic kidney disease with a missense mutation in the repeated region of PKD1 , 1998, Human Genetics.

[10]  A. Evan,et al.  Cyst formation and growth in autosomal dominant polycystic kidney disease. , 1987, Kidney international.

[11]  N. Gretz,et al.  Mutant polycystin-2 induces proliferation in primary rat tubular epithelial cells in a STAT-1/p21-independent fashion accompanied instead by alterations in expression of p57KIP2 and Cdk2 , 2008, BMC nephrology.

[12]  P. Wilson.  Mouse models of polycystic kidney disease. , 2008, Current topics in developmental biology.

[13]  E. Avner,et al.  New insights into the molecular pathophysiology of polycystic kidney disease. , 1999, Kidney international.

[14]  S. Somlo,et al.  Effective treatment of an orthologous model of autosomal dominant polycystic kidney disease , 2004, Nature Medicine.

[15]  P. Igarashi,et al.  Acute kidney injury and aberrant planar cell polarity induce cyst formation in mice lacking renal cilia. , 2008, Human molecular genetics.

[16]  Bob van de Water,et al.  Toxic tubular injury in kidneys from Pkd1-deletion mice accelerates cystogenesis accompanied by dysregulated planar cell polarity and canonical Wnt signaling pathways. , 2009, Human molecular genetics.

[17]  V. Torres,et al.  Effectiveness of vasopressin V2 receptor antagonists OPC-31260 and OPC-41061 on polycystic kidney disease development in the PCK rat. , 2005, Journal of the American Society of Nephrology : JASN.

[18]  A. Chapman.  Approaches to testing new treatments in autosomal dominant polycystic kidney disease: insights from the CRISP and HALT-PKD studies. , 2008, Clinical journal of the American Society of Nephrology : CJASN.

[19]  N. Hollenberg,et al.  Pathways for angiotensin II generation in intact human tissue: evidence from comparative pharmacological interruption of the renin system. , 1998, Hypertension.

[20]  M. Bihoreau,et al.  Characterization of a major modifier locus for polycystic kidney disease (Modpkdr1) in the Han:SPRD(cy/+) rat in a region conserved with a mouse modifier locus for Alport syndrome. , 2002, Human molecular genetics.

[21]  Roland Eils,et al.  Group testing for pathway analysis improves comparability of different microarray datasets , 2006, Bioinform..

[22]  Y. Tao,et al.  Effect of statin and angiotensin-converting enzyme inhibition on structural and hemodynamic alterations in autosomal dominant polycystic kidney disease model. , 2007, American journal of physiology. Renal physiology.

[23]  Jian-Kang Chen,et al.  Angiotensin IV induces tyrosine phosphorylation of focal adhesion kinase and paxillin in proximal tubule cells. , 2001, American journal of physiology. Renal physiology.

[24]  S. Somlo,et al.  Triptolide is a traditional Chinese medicine-derived inhibitor of polycystic kidney disease , 2007, Proceedings of the National Academy of Sciences.

[25]  Alessandra Boletta,et al.  PKD1 Induces p21waf1 and Regulation of the Cell Cycle via Direct Activation of the JAK-STAT Signaling Pathway in a Process Requiring PKD2 , 2002, Cell.

[26]  B. Yoder,et al.  Cystic kidney diseases: all roads lead to the cilium. , 2004, Physiology.

[27]  J. Mallolas,et al.  Loss of heterozygosity in renal and hepatic epithelial cystic cells from ADPKD1 patients , 2000, European Journal of Human Genetics.

[28]  A. Novick,et al.  The mTOR pathway is regulated by polycystin-1, and its inhibition reverses renal cystogenesis in polycystic kidney disease. , 2006, Proceedings of the National Academy of Sciences of the United States of America.

[29]  Pablo Tamayo,et al.  Gene set enrichment analysis: A knowledge-based approach for interpreting genome-wide expression profiles , 2005, Proceedings of the National Academy of Sciences of the United States of America.

[30]  H. Hammes,et al.  A truncated polycystin-2 protein causes polycystic kidney disease and retinal degeneration in transgenic rats. , 2006, Journal of the American Society of Nephrology : JASN.

[31]  G. Germino,et al.  A critical developmental switch defines the kinetics of kidney cyst formation after loss of Pkd1 , 2007, Nature Medicine.

[32]  A. Pierides,et al.  Genetic evidence for a trans-heterozygous model for cystogenesis in autosomal dominant polycystic kidney disease. , 2000, Human molecular genetics.

[33]  N. Gretz,et al.  Increased epithelial cell proliferation and abnormal extracellular matrix in rat polycystic kidney disease. , 1998, Journal of the American Society of Nephrology : JASN.

[34]  G. Gibson,et al.  Mixed-model reanalysis of primate data suggests tissue and species biases in oligonucleotide-based gene expression profiles. , 2003, Genetics.

[35]  K. Blick,et al.  Proliferative activity of cyst epithelium in human renal cystic diseases. , 1995, Journal of the American Society of Nephrology.

[36]  J. Roy.  SAS for Mixed Models, Second Edition. R. C.Littell, G. A. Milliken, W. W. Stroup, R. D. Wolfinger, and O. Schabenberger , 2007 .

[37]  Ihor V. Yosypiv.  Renin–angiotensin system–growth factor cross-talk: a novel mechanism for ureteric bud morphogenesis , 2009, Pediatric Nephrology.

[38]  A. Pierides,et al.  Germinal and somatic mutations in the PKD2 gene of renal cysts in autosomal dominant polycystic kidney disease. , 1999, Human molecular genetics.

[39]  Laurie A. Smith,et al.  Long-lasting arrest of murine polycystic kidney disease with CDK inhibitor roscovitine , 2006, Nature.

[40]  Vincent H Gattone,et al.  Inhibition of renal cystic disease development and progression by a vasopressin V2 receptor antagonist , 2003, Nature Medicine.

[41]  A. Ong,et al.  Identification and Functional Characterization of an N-terminal Oligomerization Domain for Polycystin-2* , 2008, Journal of Biological Chemistry.

[42]  A. Ong,et al.  Pkd2 dosage influences cellular repair responses following ischemia-reperfusion injury. , 2009, The American journal of pathology.

[43]  B. Yoder,et al.  An incredible decade for the primary cilium: a look at a once-forgotten organelle. , 2005, American journal of physiology. Renal physiology.

[44]  E. Avner,et al.  EGF receptor tyrosine kinase inhibition attenuates the development of PKD in Han:SPRD rats. , 2003, Kidney international.

[45]  Y Chen,et al.  Treatment of polycystic kidney disease with a novel tyrosine kinase inhibitor. , 2000, Kidney international.

[46]  S. Wulff.  SAS for Mixed Models , 2007 .

[47]  P. Wilson,et al.  Cell biology of human autosomal dominant polycystic kidney disease. , 1991, Seminars in nephrology.

[48]  R. Speth,et al.  Chymase-like angiotensin II-generating activity in end-stage human autosomal dominant polycystic kidney disease. , 2004, Journal of the American Society of Nephrology : JASN.

[49]  P. S. St George-Hyslop,et al.  Somatic PKD2 mutations in individual kidney and liver cysts support a "two-hit" model of cystogenesis in type 2 autosomal dominant polycystic kidney disease. , 1999, Journal of the American Society of Nephrology : JASN.

[50]  J. Grantham.  1992 Homer Smith Award. Fluid secretion, cellular proliferation, and the pathogenesis of renal epithelial cysts. , 1993, Journal of the American Society of Nephrology : JASN.

[51]  J. Wright,et al.  A role for the angiotensin IV/AT4 system in mediating natriuresis in the rat , 2001, Peptides.