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Human ubiquitin‐protein ligase Nedd4: expression, subcellular localization and selective interaction with ubiquitin‐conjugating enzymes
Author(s) -
Anan Tadashi,
Nagata Yoichi,
Koga Hisashi,
Honda Yoshiomi,
Yabuki Nami,
Miyamoto Chikara,
Kuwano Akira,
Matsuda Ichiro,
Endo Fumio,
Saya Hideyuki,
Nakao Mitsuyoshi
Publication year - 1998
Publication title -
genes to cells
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.912
H-Index - 115
eISSN - 1365-2443
pISSN - 1356-9597
DOI - 10.1046/j.1365-2443.1998.00227.x
Subject(s) - nedd4 , ubiquitin , ubiquitin ligase , biology , ubiquitin conjugating enzyme , cytoplasm , deubiquitinating enzyme , microbiology and biotechnology , subcellular localization , dna ligase , ubiquitin protein ligases , biochemistry , enzyme , gene
Background Nedd4 is a ubiquitin‐protein ligase containing a calcium/lipid‐binding domain, multiple WW domains and a C‐terminal Hect domain, which is required for both the ubiquitin transfer and the association with E2 ubiquitin‐conjugating enzymes. Nedd4 has been reported to be involved in the selective ubiquitination of some regulatory proteins in transcription and membrane transport. Results Three mRNA species for human Nedd4 were found to be 6.4‐, 7.8‐ and 9.5‐kb in size, and their expression patterns varied among normal tissues and cancer cell lines, indicating the tissue‐ and cell‐specificities of Nedd4 expression. The Nedd4 protein, ≈120 kDa in weight, was found in the cytoplasm, mainly in the perinuclear region and cytoplasmic periphery, of human cultured cells. Neural differentiation induced not only the down‐regulation of Nedd4 but also the localization of the protein to both the cytoplasm and neurites. To identify the ubiquitination pathway that is linked to Nedd4, we demonstrated that specific E2 enzymes, including human Ubc4, UbcH5B, UbcH5C, UbcH6 and UbcH7, could transfer ubiquitin molecules to Nedd4 at the active cysteine residue, whereas E6AP accepted ubiquitins from Ubc4, UbcH5B, UbcH5C and UbcH7. Furthermore, nuclear localization of N‐terminal deletion mutant Nedd4 enabled us to investigate the interaction between Nedd4 and E2 enzyme (Ubc4 or UbcH7) in the cell. The simultaneous expression of the full‐length Nedd4 and E2 enzyme revealed that both proteins mostly colocalized in the cytoplasmic periphery, while the N‐terminal deleted Nedd4 induced the nuclear and perinuclear colocalization with E2 enzyme. Conclusion Our findings suggested that Nedd4 plays an important role in the cell regulation, including neural differentiation through cooperation with specific E2 ubiquitination pathways.