Title

PTEN enters the nucleus by diffusion

UMMS Affiliation

Department of Biochemistry and Molecular Pharmacology; Department of Cell Biology

Publication Date

2005-08-10

Document Type

Article

Subjects

Cell Line, Tumor; Cell Nucleus; Diffusion; Humans; Microscopy, Fluorescence; Molecular Weight; Mutation; Phosphoric Monoester Hydrolases; Protein Transport; Recombinant Proteins

Disciplines

Biochemistry, Biophysics, and Structural Biology | Cell Biology | Pharmacology, Toxicology and Environmental Health

Abstract

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.

DOI of Published Version

10.1002/jcb.20525

Source

J Cell Biochem. 2005 Oct 1;96(2):221-34. Link to article on publisher's site

Journal/Book/Conference Title

Journal of cellular biochemistry

Related Resources

Link to Article in PubMed

PubMed ID

16088943

Share

COinS