The tumour suppressor protein, PTEN (phosphatase and tensin homolog deleted on chromosome 10), is a phosphatase that can dephosphorylate tyrosine-containing peptides, Shc, focal adhesion kinase and phosphoinositide substrates. In cellular assays, PTEN has been shown to antagonize the PI-3K-dependent activation of protein kinase B (PKB) and to inhibit cell spreading and motility. It is currently unclear, however, whether PTEN accomplishes these effects through its lipid- or protein-phosphatase activity, although strong evidence has demonstrated the importance of the latter for tumour suppression by PTEN. By using a PTEN G129E (Gly129 → Glu) mutant that has lost its lipid phosphatase activity, while retaining protein phosphatase activity, we demonstrated a requirement for the lipid phosphatase activity of PTEN in the regulation of PKB activity, cell viability and membrane ruffling. We also made a small C-terminal deletion of PTEN, removing a putative PDZ (PSD95, Dlg and ZO1)-binding motif, with no detectable effect on the phosphatase activity of the protein expressed in HEK293 cells (human embryonic kidney 293 cells) assayed in vitro. Surprisingly, expression of this mutant revealed differential requirements for the C-terminus in the different functional assays. Wild-type and C-terminally deleted PTEN appeared to be equally active in down-regulating PKB activity, but this mutant enzyme had no effect on platelet-derived growth factor (PDGF)-induced membrane ruffling and was only partially active in a cell viability assay. These results stress the importance of the lipid phosphatase activity of PTEN in the regulation of several signalling pathways. They also identify a mutation, similar to mutations that occur in some human tumours, which removes the effect of PTEN on membrane ruffling but not that on PKB.
Skip Nav Destination
Article navigation
March 2000
-
Cover Image
Cover Image
- PDF Icon PDF LinkFront Matter
- PDF Icon PDF LinkTable of Contents
Research Article|
March 07 2000
Analysis of the cellular functions of PTEN using catalytic domain and C-terminal mutations: differential effects of C-terminal deletion on signalling pathways downstream of phosphoinositide 3-kinase
Nick R. LESLIE;
2To whom correspondence should be addressed (e-mail n.r.leslie@dundee.ac.uk).
Search for other works by this author on:
Ian PASS;
Ian PASS
1Division of Signal Transduction Therapy, Department of Biochemistry, University of Dundee, Dundee DD1 5EH, U.K.
Search for other works by this author on:
Elaine A. ORCHISTON;
Elaine A. ORCHISTON
1Division of Signal Transduction Therapy, Department of Biochemistry, University of Dundee, Dundee DD1 5EH, U.K.
Search for other works by this author on:
C. Peter DOWNES
C. Peter DOWNES
1Division of Signal Transduction Therapy, Department of Biochemistry, University of Dundee, Dundee DD1 5EH, U.K.
Search for other works by this author on:
Publisher: Portland Press Ltd
Received:
August 31 1999
Revision Received:
December 13 1999
Accepted:
January 11 2000
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London © 2000
2000
Biochem J (2000) 346 (3): 827–833.
Article history
Received:
August 31 1999
Revision Received:
December 13 1999
Accepted:
January 11 2000
Citation
Nick R. LESLIE, Alex GRAY, Ian PASS, Elaine A. ORCHISTON, C. Peter DOWNES; Analysis of the cellular functions of PTEN using catalytic domain and C-terminal mutations: differential effects of C-terminal deletion on signalling pathways downstream of phosphoinositide 3-kinase. Biochem J 15 March 2000; 346 (3): 827–833. doi: https://doi.org/10.1042/bj3460827
Download citation file:
Sign in
Don't already have an account? Register
Sign in to your personal account
You could not be signed in. Please check your email address / username and password and try again.
Captcha Validation Error. Please try again.