1. Monoubiquitination of EEA1 regulates endosome fusion and trafficking
- Author
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Yihong Ye, Guofeng Zhang, and Harish N. Ramanathan
- Subjects
biology ,Endosome ,Ubiquitin ,Research ,Ubiquitin-conjugating enzyme ,EEA1 ,Endocytosis ,Phenotype ,General Biochemistry, Genetics and Molecular Biology ,Ubiquitin ligase ,Cell biology ,Endosome fusion ,Rab5 ,Immunology ,E3-independent ubiquitination ,biology.protein ,Monoubiquitination ,Endosome recycling - Abstract
Background Early endosomal autoantigen 1 (EEA1) is a membrane tethering factor required for the fusion and maturation of early endosomes in endocytosis. How the activity of EEA1 is regulated in cells is unclear. Results Here we show that endogenous EEA1 is prone to monoubiquitination at multiple sites, owing to an intrinsic affinity to ubiquitin conjugating enzymes (E2). The E2 interactions enable a ubiquitin ligase (E3) independent mechanism that decorate EEA1 with multiple mono-ubiquitin moieties. Expression of an ubiquitin-EEA1 chimera that mimics native mono-ubiquitinated EEA1 generates giant endosomes abutting the nucleus. Several lines of evidence suggest that this phenotype is due to increased endosome fusion and a simultaneous blockade on an endosome recycling pathway. The latter is likely caused by diminished endosome fission in cells expressing ubiquitin-EEA1. Conclusion Our results demonstrate that ubiquitination may dramatically affect the activity of an endosome fusion factor to alter endosome morphology and trafficking pattern, and thereby implicating an unexpected role of ubiquitin signaling in endocytosis. more...
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