title: Mono-ubiquitination drives nuclear export of the human DCN1-like protein hDCNL1.
abstract: Conjugation of Nedd8 to a cullin protein, termed neddylation, is an evolutionarily conserved process that functions to activate the cullin-RING family E3 ubiquitin ligases, leading to increased proteasomal degradation of a wide range of substrate proteins. Recent emerging evidence demonstrates that cellular neddylation requires the action of Dcn1, which, in humans, consists of five homologues designated as hDCNL1-5. Here we revealed a previously unknown mechanism that regulates hDCNL1. In cultured mammalian cells ectopically expressed hDCNL1 was mono-ubiquitinated predominantly at K143, K149, and K171. Using a classical chromatographic purification strategy, we identified Nedd4-1 as an E3 ligase that can catalyze mono-ubiquitination of hDCNL1 in a reconstituted ubiquitination system. In addition, the hDCNL1 N-terminal ubiquitin-binding domain is necessary and sufficient to mediate mono-ubiquitination. Finally, fluorescence microscopic and subcellular fractionation analyses revealed a role for mono-ubiquitination in driving nuclear export of hDCNL1. Taken together, these results suggest a mono-ubiquitination-mediated mechanism that governs nuclear-cytoplasmic trafficking of hDCNL1, thereby regulating hDCNL1-dependent activation of the cullin-RING E3 ubiquitin ligases in selected cellular compartments.
authors.affiliation: Department of Oncological Sciences, The Mount Sinai School of Medicine, New York, New York 10029-6574, USA.
authors.forename: Kenneth
authors.initials: K
authors.lastname: Wu
authors.forename: Hua
authors.initials: H
authors.lastname: Yan
authors.forename: Lei
authors.initials: L
authors.lastname: Fang
authors.forename: Xinjiang
authors.initials: X
authors.lastname: Wang
authors.forename: Cathie
authors.initials: C
authors.lastname: Pfleger
authors.forename: Xuejun
authors.initials: X
authors.lastname: Jiang
authors.forename: Lan
authors.initials: L
authors.lastname: Huang
authors.forename: Zhen-Qiang
authors.initials: ZQ
authors.lastname: Pan
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000502:physiology; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism*; D003593:Cytoplasm / Q000235:genetics / Q000378:metabolism*; D056827:Endosomal Sorting Complexes Required for Transport / Q000235:genetics / Q000378:metabolism*; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D000075702:Nedd4 Ubiquitin Protein Ligases; D017434:Protein Structure, Tertiary; D011506:Proteins; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*; D054875:Ubiquitination / Q000502:physiology*
chemical_list: C408631:DCUN1D1 protein, human; D056827:Endosomal Sorting Complexes Required for Transport; D047908:Intracellular Signaling Peptides and Proteins; D011506:Proteins; D011518:Proto-Oncogene Proteins; D000075702:Nedd4 Ubiquitin Protein Ligases; C000618483:Nedd4 protein, human; D044767:Ubiquitin-Protein Ligases