The cytoplasmic C-terminus of polycystin-1 increases cell proliferation in kidney epithelial cells through serum-activated and Ca{sup 2+}-dependent pathway(s)
- Department of Biochemistry and Molecular Biology, University of Ferrara, Via Luigi Borsari 46, I-44100 Ferrara (Italy)
- Section of Medical Genetics, University of Ferrara, Via Luigi Borsari 46, I-44100 Ferrara (Italy)
- Section of Clinical Pathology, University of Ferrara, Via Luigi Borsari 46, I-44100 Ferrara (Italy)
- Section of General Pathology, University of Ferrara, Via Luigi Borsari 46, I-44100 Ferrara (Italy)
- Department of Biochemistry and Molecular Biology, University of Ferrara, Via Luigi Borsari 46, I-44100 Ferrara (Italy) and Department of Experimental and Diagnostic Medicine, University of Ferrara, Via Luigi Borsari 46, I-44100 Ferrara (Italy)
Polycystin-1 (PC1) is a large transmembrane protein important in renal differentiation and defective in most cases of autosomal dominant polycystic kidney disease (ADPKD), a common cause of renal failure in adults. Although the genetic basis of ADPKD has been elucidated, molecular and cellular mechanisms responsible for the dysregulation of epithelial cell growth in ADPKD cysts are still not well defined. We approached this issue by investigating the role of the carboxyl cytoplasmic domain of PC1 involved in signal transduction on the control of kidney cell proliferation. Therefore, we generated human HEK293 cells stably expressing the PC1 cytoplasmic tail as a membrane targeted TrkA-PC1 chimeric receptor protein (TrkPC1). We found that TrkPC1 increased cell proliferation through an increase in cytoplasmic Ca{sup 2+} levels and activation of PKC{alpha}, thereby upregulating D1 and D3 cyclin, downregulating p21{sup waf1} and p27{sup kip1} cyclin inhibitors, and thus inducing cell cycle progression from G0/G1 to the S phase. Interestingly, TrkPC1-dependent Ca{sup 2+} increase and PKC{alpha} activation are not constitutive, but require serum factor(s) as parallel component. In agreement with this observation, a significant increase in ERK1/2 phosphorylation was observed. Consistently, inhibitors specifically blocking either PKC{alpha} or ERK1/2 prevented the TrkPC1-dependent proliferation increase. NGF, the TrkA ligand, blocked this increase. We propose that in kidney epithelial cells the overexpression of PC1 C-terminus upregulates serum-evoked intracellular Ca{sup 2+} by counteracting the growth-suppression activity of endogenous PC1 and leading to an increase in cell proliferation.
- OSTI ID:
- 20717563
- Journal Information:
- Experimental Cell Research, Vol. 304, Issue 2; Other Information: DOI: 10.1016/j.yexcr.2004.10.023; PII: S0014-4827(04)00627-5; Copyright (c) 2004 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0014-4827
- Country of Publication:
- United States
- Language:
- English
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