Disease relevance of EEA1

• Furthermore, part of this trafficking involves the transit of HIV-1 from transferrin-negative to EEA1 and transferrin-positive endosomes, suggesting a merger from nonclassical to classical endocytic pathways in these cells [1].
• Phagosomes containing Mycobacterium tuberculosis do not acquire the PI(3)P-binding protein EEA1, which is required for phagosome maturation [2].
• Autoantibodies to EEA1 have been described in patients with neurological diseases, subacute cutaneous lupus and a variety of other conditions, including a patient with Wegener's granulomatosis (WG) [3].
• Autoantibodies to EEA1, an antigen on early endosomes, were first reported in the serum of a patient with subacute cutaneous lupus erythematosus (SCLE) [4].
• Immunocytochemistry showed that endobrevin is associated with tubulo-vesicular structures, which are colocalized with early endosomes labeled by early endosome antigen (EEA)-1 in insulinoma MIN6 cells [5].

High impact information on EEA1

• We propose a novel mechanism whereby oligomeric EEA1 and NSF mediate the local activation of syntaxin 13 upon membrane tethering and, by analogy with viral fusion proteins, coordinate the assembly of a fusion pore [6].
• Syntaxin 13, the t-SNARE required for endosome fusion, is transiently incorporated into the large oligomers via direct interactions with EEA1 [6].
• Rab5 and other associated proteins seem to act upstream of EEA1, implying that Rab5 effectors comprise both regulatory molecules and mechanical components of the membrane transport machinery [7].
• We further show that EEA1 mediates endosome docking and, together with SNAREs, leads to membrane fusion [7].
• Perforin also triggers the rapid endocytosis of granzymes into large EEA-1-staining vesicles [8].

Biological context of EEA1

• Phosphorylation of EEA1 by p38 MAP kinase regulates mu opioid receptor endocytosis [9].
• EEA1, an early-endosomal protein originally identified as an autoantigen, is essential for endocytic membrane fusion [10].
• The ability of the C-terminus of EEA1 to dimerize correlates with its ability to bind to Rab5 and early endosomes, whereas its binding to PtdIns3P is independent of dimerization [10].
• These results suggest that EEA1 is involved in neuronal synaptic vesicle function and axonal transport and growth [11].
• The underlying mechanism entails phosphorylation of EGFR at a short segment (amino acids 1002-1022) containing multiple serines and threonines, as well as phosphorylation of two Rab5 effectors, EEA1 and GDI [12].

Anatomical context of EEA1

• EGF also enhanced translocation of the Rab5 effector, early endosomal autoantigen 1 (EEA1), from cytosol to membrane [13].
• Induction of p38 mitogen-activated protein kinase reduces early endosome autoantigen 1 (EEA1) recruitment to phagosomal membranes [14].
• Our results suggest that EEA1 is a tethering molecule that provides directionality to vesicular transport from the plasma membrane to the early endosomes [15].
• Consistent with the increase in EEA1 association and its role in phagosomal maturation, the pharmacological block of p38 activity caused phagosomal acidification and enrichment of the late endocytic markers lysobisphosphatidic acid and CD63 (lysosomal integral membrane protein 1) on mycobacterial phagosomes [14].
• Selective membrane recruitment of EEA1 suggests a role in directional transport of clathrin-coated vesicles to early endosomes [15].

Associations of EEA1 with chemical compounds

• PtdIns(3)P binding by the FYVE domain of human early endosome autoantigen 1 (EEA1), a protein implicated in endosome fusion, involves two beta hairpins and an alpha helix [16].
• Interaction of the EEA1 FYVE finger with phosphatidylinositol 3-phosphate and early endosomes. Role of conserved residues [17].
• Glycerol gradient centrifugation experiments indicated that native EEA1 had the same hydrodynamic properties as the approximately 350-kDa crosslinked complex [10].
• Then, AQP2 moved from EEA1-positive endosomes to the subapical AQP2-storage compartment, which is sensitive to wortmannin and LY294002 [18].
• The disruption of actin filaments with cytochalasin D or latrunculin B induced the accumulation of AQP2 in EEA1-positive early endosomes [19].

Physical interactions of EEA1

• The ProF protein partially co-localizes with EEA1 on vesicular structures and binds to the protein kinases Akt and PKCzeta/lambda (protein kinase Czeta/lambda) via its WD-repeat propeller [20].

Co-localisations of EEA1

• Washout of forskolin induced retrieval of AQP2 into the cytoplasm, and AQP2 was transiently colocalized with EEA1-positive endosomes [18].
• Confocal immunofluorescence microscopy of transfected HEp2 cells revealed that the C-terminal part (residues 1277-1411) of EEA1 colocalizes extensively with a GTPase-deficient mutant of the early endosomal GTPase Rab5, while deletion of the FYVE finger or mutations that interfere with zinc binding cause a cytosolic localization [21].
• STAMP2 also localizes to vesicular-tubular structures in the cytosol and colocalizes with the Early Endosome Antigen1 (EEA1) suggesting that it may be involved in the secretory/endocytic pathways [22].
• STAMP1 also localizes to vesicular tubular structures in the cytosol and colocalizes with the early endosome antigen 1 (EEA1), suggesting that it may be involved in the secretory/endocytic pathways [23].

Regulatory relationships of EEA1

• However, coexpression of Rab4-Q67L with CD2AP/CMS induces a significant enlargement of EEA1-positive early endosomes [24].
• Immunofluorescence microscopy studies revealed substantial PAR1 accumulation in an early endosome antigen-1-positive compartment in agonist-treated cells expressing SNX1 C terminus [25].
• The mutant full-length EEA1 caused the accumulation of endosome clusters and suppressed the enlargement of endosomes caused by a persistently active form of Rab5 (Rab5Q79L) [26].
• In Caco-2 cells, a cell line thought to model human enterocytes, ClC-4 protein is expressed on the cell surface and also partially co-localizes with EEA1 and transferrin, marker molecules of early and recycling endosomes, respectively [27].

Other interactions of EEA1

• Ten minutes after internalization at 37C, Y992- and Y1173-phosphorylated EGFR were almost exclusively located in early endosomes, as shown by co-localization with EEA1 [28].
• After the translocation to the plasma membrane, AQP2 was endocytosed to EEA1-positive early endosomes, and then transferred back to the original Rab11-positive compartment [19].
• Therefore, SNX5 is localized to a subdomain of the early endosome distinct from EEA1 and, following EGF stimulation and elevation of PtdIns3,4P2, is also transiently recruited to the plasma membrane [29].
• By contrast, depletion of RabGAP-5 results in increased endosome size, more endosome-associated EEA1, and disrupts the trafficking of EGF and LAMP1 [30].
• Furthermore, although both EEA1 and Rabenosyn-5 are required for early endosomal fusion, only overexpression of Rabenosyn-5 inhibits cathepsin D processing, suggesting that the two proteins play distinct roles in endosomal trafficking [31].

Analytical, diagnostic and therapeutic context of EEA1

• Immunofluorescence showed that EEA1 appeared on the membrane of FDx-labeled macropinosomes at that time, suggesting that EEA1 functioned in homotypic macropinosome fusion [32].
• Confocal microscopy demonstrated that diphtheria toxin is transported to vesicles containing EEA1, a marker for early endosomes [33].
• Three of seven sera selected for epitope mapping studies bound to EEA1 peptides represented by amino acids 1096-1125, and two reacted with peptides represented by amino acids 1296-1320 [34].
• Of the 36 sera that produced an identical staining pattern as the prototype and immune rabbit sera, 8 (22%) had IgG antibodies that recognized the recombinant EEA1 protein when tested by immunoblotting and immunoprecipitation assays [35].
• By indirect immunofluorescence (IIF), the index serum produced a unique cytoplasmic discrete speckled (CDS) staining pattern that partially colocalized with early endosome antigen 1 (EEA1) but not Golgi complex or other cytoplasmic organelles in HEp-2 cells [36].

References