Letter | Published:

EEA1 links PI(3)K function to Rab5 regulation of endosome fusion

Nature volume 394, pages 494498 (30 July 1998) | Download Citation

Subjects

Abstract

GTPases and lipid kinases regulate membrane traffic along the endocytic pathway by mechanisms that are not completely understood1,2,3,4. Fusion between early endosomes requires phosphatidyl-inositol-3-OH kinase (PI(3)K) activity5,6,7 as well as the small GTPase Rab5 (ref. 8). Excess Rab5–GTP complex restores endosome fusion when PI(3)K is inhibited5,9. Here we identify the early-endosomal autoantigen EEA1 (10,​11,​12) which binds the PI(3)K product phosphatidylinositol-3-phosphate, as a new Rab5 effector that is required for endosome fusion. The association of EEA1 with the endosomal membrane requires Rab5–GTP and PI(3)K activity, and excess Rab5–GTP stabilizes the membrane association of EEA1 even when PI(3)K is inhibited. The identification of EEA1 as a direct Rab5 effector provides a molecular link between PI(3)K and Rab5, and its restricted distribution to early endosomes10 indicates that EEA1 may confer directionality to Rab5-dependent endocytic transport.

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References

  1. 1.

    & The diversity of Rab proteins in vesicle transport. Curr. Opin. Cell Biol. 9, 496–504 (1997).

  2. 2.

    & Role of rab GTPases in membrane traffic. Int. Rev. Cytol. 176, 1–85 (1997).

  3. 3.

    & The role of lipid signaling in constitutive membrane traffic. Curr. Opin. Cell Biol. 9, 519–526 (1997).

  4. 4.

    , , & Phosphoinositides as regulators in membrane traffic. Science 271, 1533–1539 (1996).

  5. 5.

    Evidence for phosphatidylinositol 3-kinase as a regulator of endocytosis via activation of Rab5. Proc. Natl Acad. Sci. USA 92, 10207–10211 (1995).

  6. 6.

    & Phosphatidylinositol 3-kinase activity is required for early endosome fusion. Biochem. J. 311, 31–34 (1995).

  7. 7.

    , , & Wortmannin alters the transferrin receptor endocytic pathway in vivo and in vitro. Mol. Biol. Cell 7, 355–367 (1996).

  8. 8.

    , , & rab5 controls early endosome fusion in vitro. Cell 64, 915–925 (1991).

  9. 9.

    , , , & Inhibition of endosome fusion by wortmannin persists in the presence of activated rab5. Mol. Biol. Cell 9, 323–332 (1998).

  10. 10.

    EEA1, an early endosome-associated protein. EEA1 is a conserved alpha-helical peripheral membrane protein flanked by cysteine “fingers” and contains a calmodulin-binding IQ motif. J. Biol. Chem. 270, 13503–13511 (1995).

  11. 11.

    , , , , & Identification of an early endosomal protein regulated by phosphatidylinositol 3-kinase. Proc. Natl Acad. Sci. USA 94, 7326–7330 (1997).

  12. 12.

    et al. Afunctional PtdIns(3)P-binding motif. Nature 394, 433–434 (1998).

  13. 13.

    , , & Endosomal localization of the autoantigen EEA1 is mediated by a zinc-binding FYVE finger. J. Biol. Chem. 271, 24048–24054 (1996).

  14. 14.

    Distinct Rab-binding domains mediate the interaction of rabaptin-5 with GTP-bound rab4 and rab5. EMBO J. 17, 1941–1951 (1998).

  15. 15.

    , , , , & Inhibition of rab5 GTPase activity stimulates membrane fusion in endocytosis. EMBO J. 13, 1287–1296 (1994).

  16. 16.

    Anovel Rab5 GDP/GTP exchange factor complexed to rabaptin-5 links nucleotide exchange to effector recruitment and function. Cell 90, 1149–1159 (1997).

  17. 17.

    , , & Potential sites of PI-3 kinase function in the endocytic pathway revealed by the PI-3 kinase inhibitor, wortmannin. J. Cell Biol. 132, 595–605 (1996).

  18. 18.

    GTPase activity of Rab5 acts as a timer for endocytic membrane fusion. Nature 383, 266–269 (1996).

  19. 19.

    , , & Microtubules are involved in bafilomycin A1-induced tubulation and Rab5-dependent vacuolation of early endosomes. Eur. J. Cell Biol. 72, 95–103 (1997).

  20. 20.

    , , & Rabaptin-5 is a direct effector of the small GTPase Rab5 in endocytic membrane fusion. Cell 83, 423–432 (1995).

  21. 21.

    , , , & Localization of low molecular weight GTP binding proteins to exocytic and endocytic compartments. Cell 62, 317–329 (1990).

  22. 22.

    The small GTPase rab5 functions as a regulatory factor in the early endocytic pathway. Cell 70, 715–728 (1992).

  23. 23.

    , & Mammalian Ras interacts directly with the serine/threonine kinase Raf. Cell 74, 205–214 (1993).

  24. 24.

    , & Expression of Rab GTPases using recombinant vaccinia viruses. Methods Enzymol. 257, 155–164 (1995).

  25. 25.

    , , & Isolation of monoclonal antibodies specific for human c-myc proto-oncogene product. Mol. Cell. Biol. 5, 3610–3616 (1985).

  26. 26.

    & Tubular early endosome networks in AtT20 and other cells. J. Cell Biol. 115, 635–653 (1991).

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Acknowledgements

We thank E. Rønning for technical assistance; D. Warren for help with the baculovirus system; N. Salmon and T. Nordeng for help with confocal microscopy; V. Rybin for providing the Rab5D136N–Rep1 complex; E. Kolpakova for anti-MBP antibodies; and H. McBride, S. Olsnes, K.Sandvig and B. Sönnichsen for comments on the manuscript. H.S. was supported by the Top Research Programme, the Research Council of Norway, the Norwegian Cancer Society and the Novo Nordisk Foundation. This work was supported by a European Community TMR grant (to H.S. and M.Z.).

Author information

Author notes

    • Anne Simonsen
    •  & Roger Lippe

    These authors contributed equally to this work

    • Carol Murphy

    Present address: University of Ioannina Medical School, 45110 Ioannina, Greece.

Affiliations

  1. *Department of Biochemistry, The Norwegian Radium Hospital, Montebello, N-0310 Oslo, Norway

    • Anne Simonsen
    • , Jean-Michel Gaullier
    •  & Harald Stenmark
  2. ‡EMBL, Meyerhofstrasse 1, D-69012 Heidelberg, Germany

    • Roger Lippe
    • , Savvas Christoforidis
    • , Carol Murphy
    •  & Marino Zerial
  3. §EM-unit, Institute of Biology, PO Box 1050, Blindern, N-0316 Oslo, Norway

    • Andreas Brech
  4. Department of Pathology and Immunology, Monash Medical School, Prahran, Victoria 3181, Australia

    • Judy Callaghan
    •  & Ban-Hock Toh
  5. #Max Planck Institute for Molecular Cell Biology and Genetics, Dresden, 01307, Germany

    • Roger Lippe
    • , Savvas Christoforidis
    • , Carol Murphy
    •  & Marino Zerial

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Correspondence to Harald Stenmark.

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https://doi.org/10.1038/28879

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