Authors
Liu, FenghuaWagner, Stefan R.
Campbell, Robert B.
Nickerson, Jeffrey A.
Schiffer, Celia A.
Ross, Alonzo H.
UMass Chan Affiliations
Department of Cell BiologyDepartment of Biochemistry and Molecular Pharmacology
Document Type
Journal ArticlePublication Date
2005-08-10Keywords
Cell Line, TumorCell Nucleus
Diffusion
Humans
Microscopy, Fluorescence
Molecular Weight
Mutation
Phosphoric Monoester Hydrolases
Protein Transport
Recombinant Proteins
Biochemistry, Biophysics, and Structural Biology
Cell Biology
Pharmacology, Toxicology and Environmental Health
Metadata
Show full item recordAbstract
Despite much evidence for phosphatidylinositol phosphate (PIP)-triggered signaling pathways in the nucleus, there is little understanding of how the levels and activities of these proteins are regulated. As a first step to elucidating this problem, we determined whether phosphatase and tensin homolog deleted on chromosome 10 (PTEN) enters the nucleus by passive diffusion or active transport. We expressed various PTEN fusion proteins in tsBN2, HeLa, LNCaP, and U87MG cells and determined that the largest PTEN fusion proteins showed little or no nuclear localization. Because diffusion through nuclear pores is limited to proteins of 60,000 Da or less, this suggests that nuclear translocation of PTEN occurs via diffusion. We examined PTEN mutants, seeking to identify a nuclear localization signal (NLS) for PTEN. Mutation of K13 and R14 decreased nuclear localization, but these amino acids do not appear to be part of an NLS. We used fluorescence recovery after photobleaching (FRAP) to demonstrate that GFP-PTEN can passively pass through nuclear pores. Diffusion in the cytoplasm is retarded for the PTEN mutants that show reduced nuclear localization. We conclude that PTEN enters the nucleus by diffusion. In addition, sequestration of PTEN in the cytoplasm likely limits PTEN nuclear translocation.Source
J Cell Biochem. 2005 Oct 1;96(2):221-34. Link to article on publisher's siteDOI
10.1002/jcb.20525Permanent Link to this Item
http://hdl.handle.net/20.500.14038/26140PubMed ID
16088943Related Resources
Link to Article in PubMedae974a485f413a2113503eed53cd6c53
10.1002/jcb.20525