Crucial role of the C-terminus of PTEN in antagonizing NEDD4-1-mediated PTEN ubiquitination and degradation.
PTEN (phosphatase and tensin homologue deleted on chromosome 10), a potent tumour suppressor and multifunctional signalling protein, is under intricate regulation. In the present study, we have investigated the mechanism and regulation of PTEN ubiquitination catalysed by NEDD4-1 (neural-precursor-cell-expressed, developmentally down-regulated 4-1), a ubiquitin ligase for PTEN we identified recently. Using the reconstituted assay and cellular analysis, we demonstrated that NEDD4-1-mediated PTEN ubiquitination depends on its intact HECT (homologous to E6-associated protein C-terminus) domain. Instead of using its WW domains (protein-protein interaction domains containing two conserved tryptophan residues) as a protein interaction module, NEDD4-1 interacts with PTEN through its N-terminal region containing a C2 domain as well as the HECT domain. Strikingly, we found that a C-terminal truncated PTEN fragment binds to NEDD4-1 with higher affinity than the full-length PTEN, suggesting an intrinsic inhibitory effect of the PTEN C-terminus on PTEN-NEDD4-1 interaction. Moreover, the C-terminal truncated PTEN is more sensitive to NEDD4-1-mediated ubiquitination and degradation. Therefore the present study reveals that the C-terminus of PTEN plays a critical role in stabilizing PTEN via antagonizing NEDD4-1-induced PTEN protein decay; conversely, truncation of the PTEN C-terminus results in rapid NEDD4-1-mediated PTEN degradation, a possible mechanism accounting for attenuation of PTEN function by certain PTEN mutations in human cancers.
Wang
Xinjiang
X
Cell Biology Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA.
Shi
Yuji
Y
Wang
Junru
J
Huang
Guochang
G
Jiang
Xuejun
X
D000818:Animals; D002460:Cell Line; D056827:Endosomal Sorting Complexes Required for Transport; D006801:Humans; D000075702:Nedd4 Ubiquitin Protein Ligases; D051059:PTEN Phosphohydrolase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism*; D018411:Spodoptera; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*; D054875:Ubiquitination
D056827:Endosomal Sorting Complexes Required for Transport; D011994:Recombinant Proteins; D000075702:Nedd4 Ubiquitin Protein Ligases; C000618483:Nedd4 protein, human; D044767:Ubiquitin-Protein Ligases; D051059:PTEN Phosphohydrolase