Project description:Autosomal dominant polycystic kidney disease (ADPKD) is characterized by the formation of multiple fluid-filled cysts that destroy the kidney architecture resulting in end-stage renal failure. Mutations in the ADPKD genes PKD1 and PKD2 account for nearly all the cases of ADPKD. Increased cell proliferation is one of the key features of the disease. Several studies indicated that polycystin-1, the product of PKD1, regulates cellular proliferation through various signaling pathways, but little is known about the role played by polycystin-2, the product of PKD2. Recently, it was reported that as with polycystin-1, polycystin-2 can acts as a negative regulator of cell growth by modulating the levels of the cyclin-dependent kinase inhibitor, p21 and the activity of the cyclin-dependent kinase 2, Cdk2. In this study we utilized different kidney cell lines expressing wild-type and mutant PKD2 as well as primary tubular epithelial cells isolated from a PKD transgenic rat to further explore the contribution of the p21/Cdk2 pathway in ADPKD proliferation. Surprisingly, over-expression of wild-type PKD2 in renal cell lines failed to inactivate Cdk2 activity and consequently had no effect on cell proliferation. On the other hand, expression of mutated PKD2 augmented proliferation only in the primary tubular epithelial cells of a rat model but this was independent of STAT-1/p21 pathway. Genome-wide expression analysis in these cells revealed that expression of the cyclin-dependent kinase inhibitor, p57 is downregulated, while p21 remains unchanged. This p57 reduction is accompanied by an increase in Cdk2 levels. Our results indicate the probable involvement of p57 on epithelial cell proliferation in polycystic kidney disease. In addition, it confirms that PKD2-induced proliferation is a multifactorial process. We used microarrays to study the modulation of gene expression by mutated PKD2 in the primary tubular epithelial cells of a transgenic rat mode Keywords: transgene Gene expression in the primary tubular epithelial of a transgenic rat mode with mutated PKD2 was compared with that of SD control rats

Project description:This model is from the article: Restriction point control of the mammalian cell cycle via the cyclin E/Cdk2:p27 complex. Conradie R, Bruggeman FJ, Ciliberto A, Csikász-Nagy A, Novák B, Westerhoff HV, Snoep JL FEBS J.2010 Jan; 277(2): 357-67 20015233, Abstract: Numerous top-down kinetic models have been constructed to describe the cell cycle. These models have typically been constructed, validated and analyzed using model species (molecular intermediates and proteins) and phenotypic observations, and therefore do not focus on the individual model processes (reaction steps). We have developed a method to: (a) quantify the importance of each of the reaction steps in a kinetic model for the positioning of a switch point [i.e. the restriction point (RP)]; (b) relate this control of reaction steps to their effects on molecular species, using sensitivity and co-control analysis; and thereby (c) go beyond a correlation towards a causal relationship between molecular species and effects. The method is generic and can be applied to responses of any type, but is most useful for the analysis of dynamic and emergent responses such as switch points in the cell cycle. The strength of the analysis is illustrated for an existing mammalian cell cycle model focusing on the RP [Novak B, Tyson J (2004) J Theor Biol230, 563-579]. The reactions in the model with the highest RP control were those involved in: (a) the interplay between retinoblastoma protein and E2F transcription factor; (b) those synthesizing the delayed response genes and cyclin D/Cdk4 in response to growth signals; (c) the E2F-dependent cyclin E/Cdk2 synthesis reaction; as well as (d) p27 formation reactions. Nine of the 23 intermediates were shown to have a good correlation between their concentration control and RP control. Sensitivity and co-control analysis indicated that the strongest control of the RP is mediated via the cyclin E/Cdk2:p27 complex concentration. Any perturbation of the RP could be related to a change in the concentration of this complex; apparent effects of other molecular species were indirect and always worked through cyclin E/Cdk2:p27, indicating a causal relationship between this complex and the positioning of the RP. The rate constants presented in the paper have units [per tenth of an hour] and have been changed here to [per hour] (e.g. k16 = 0.25 not 0.025); for further confirmation of the correctness of this change, see the original model (Novak, J Theor Biol 2004 230:563).

Project description:Autosomal dominant polycystic kidney disease (ADPKD) is characterized by the formation of multiple fluid-filled cysts that destroy the kidney architecture resulting in end-stage renal failure. Mutations in the ADPKD genes PKD1 and PKD2 account for nearly all the cases of ADPKD. Increased cell proliferation is one of the key features of the disease. Several studies indicated that polycystin-1, the product of PKD1, regulates cellular proliferation through various signaling pathways, but little is known about the role played by polycystin-2, the product of PKD2. Recently, it was reported that as with polycystin-1, polycystin-2 can acts as a negative regulator of cell growth by modulating the levels of the cyclin-dependent kinase inhibitor, p21 and the activity of the cyclin-dependent kinase 2, Cdk2. In this study we utilized different kidney cell lines expressing wild-type and mutant PKD2 as well as primary tubular epithelial cells isolated from a PKD transgenic rat to further explore the contribution of the p21/Cdk2 pathway in ADPKD proliferation. Surprisingly, over-expression of wild-type PKD2 in renal cell lines failed to inactivate Cdk2 activity and consequently had no effect on cell proliferation. On the other hand, expression of mutated PKD2 augmented proliferation only in the primary tubular epithelial cells of a rat model but this was independent of STAT-1/p21 pathway. Genome-wide expression analysis in these cells revealed that expression of the cyclin-dependent kinase inhibitor, p57 is downregulated, while p21 remains unchanged. This p57 reduction is accompanied by an increase in Cdk2 levels. Our results indicate the probable involvement of p57 on epithelial cell proliferation in polycystic kidney disease. In addition, it confirms that PKD2-induced proliferation is a multifactorial process. We used microarrays to study the modulation of gene expression by mutated PKD2 in the primary tubular epithelial cells of a transgenic rat mode Keywords: transgene

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Dataset Information

Morris2002_CellCycle_CDK2Cyclin

Dataset's files

Publications

Kinetic mechanism of activation of the Cdk2/cyclin A complex. Key role of the C-lobe of the Cdk.

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