QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

Vol. 17, Issue 8, 3689-3704, August 2006

This Article Full Text Full Text (PDF) Supplemental Material All Versions of this Article: E05-10-0980v1 17/8/3689    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Kalia, M. Articles by Mayor, S. Search for Related Content PubMed PubMed Citation Articles by Kalia, M. Articles by Mayor, S.

Arf6-independent GPI-anchored Protein-enriched Early Endosomal Compartments Fuse with Sorting Endosomes via a Rab5/Phosphatidylinositol-3'-Kinase–dependent Machinery

Manjula Kalia^*, Sudha Kumari^*, Rahul Chadda^*, Michelle M. Hill, Robert G. Parton, and Satyajit Mayor^*

*National Centre for Biological Sciences, UAS-GKVK Campus, Bangalore 560065, India; and Institute for Molecular Bioscience, University of Queensland, Queensland 4072, Australia

Submitted October 25, 2005; Revised April 21, 2005; Accepted May 25, 2006
Monitoring Editor: Jean Gruenberg

In the process of internalization of molecules from the extracellular milieu, a cell uses multiple endocytic pathways, consequently generating different endocytic vesicles. These primary endocytic vesicles are targeted to specific destinations inside the cell. Here, we show that GPI-anchored proteins are internalized by an Arf6-independent mechanism into GPI-anchored protein-enriched early endosomal compartments (GEECs). Internalized GPI-anchored proteins and the fluid phase are first visualized in GEECs that are acidic, primary endocytic structures, negative for early endosomal markers, Rab4, Rab5, and early endosome antigen (EEA)1. They subsequently acquire Rab5 and EEA1 before homotypic fusion with other GEECs, and heterotypic fusion with endosomes containing cargo from the clathrin-dependent endocytic pathway. Although, the formation of GEECs is unaffected by inhibition of Rab5 GTPase and phosphatidylinositol-3'-kinase (PI3K) activity, their fusion with sorting endosomes is dependent on both activities. Overexpression of Rab5 reverts PI3K inhibition of fusion, providing evidence that Rab5 effectors play important roles in heterotypic fusion between the dynamin-independent GEECs and clathrin- and dynamin-dependent sorting endosomes.

The online version of this article contains supplemental material at MBC Online (http://www.molbiolcell.org).

Address correspondence to: Satyajit Mayor ( mayor{at}ncbs.res.in)

Abbreviations used: EEA1, early endosomal antigen; GEEC, GPI-anchored protein-enriched early endosomal compartment; PI3P, phosphatidylinositol 3'-phosphate; PKC, protein kinase C; WT, wortmannin.

This article has been cited by other articles:

				D. J. Barr, A. G. Ostermeyer-Fay, R. A. Matundan, and D. A. Brown Clathrin-independent endocytosis of ErbB2 in geldanamycin-treated human breast cancer cells J. Cell Sci., October 1, 2008; 121(19): 3155 - 3166. [Abstract] [Full Text] [PDF]

				A. Garcia-Regalado, M. L. Guzman-Hernandez, I. Ramirez-Rangel, E. Robles-Molina, T. Balla, J. Vazquez-Prado, and G. Reyes-Cruz G Protein-coupled Receptor-promoted Trafficking of G{beta}1{gamma}2 Leads to AKT Activation at Endosomes via a Mechanism Mediated by G{beta}1{gamma}2-Rab11a Interaction Mol. Biol. Cell, October 1, 2008; 19(10): 4188 - 4200. [Abstract] [Full Text] [PDF]

				S. Kumari, V. Borroni, A. Chaudhry, B. Chanda, R. Massol, S. Mayor, and F. J. Barrantes Nicotinic acetylcholine receptor is internalized via a Rac-dependent, dynamin-independent endocytic pathway J. Cell Biol., July 10, 2008; 181(7): 1179 - 1193. [Abstract] [Full Text] [PDF]

				M. Karjalainen, E. Kakkonen, P. Upla, H. Paloranta, P. Kankaanpaa, P. Liberali, G. H. Renkema, T. Hyypia, J. Heino, and V. Marjomaki A Raft-derived, Pak1-regulated Entry Participates in {alpha}2{beta}1 Integrin-dependent Sorting to Caveosomes Mol. Biol. Cell, July 1, 2008; 19(7): 2857 - 2869. [Abstract] [Full Text] [PDF]

				R. Kunita, A. Otomo, H. Mizumura, K. Suzuki-Utsunomiya, S. Hadano, and J.-E Ikeda The Rab5 Activator ALS2/alsin Acts as a Novel Rac1 Effector through Rac1-activated Endocytosis J. Biol. Chem., June 1, 2007; 282(22): 16599 - 16611. [Abstract] [Full Text] [PDF]

				N. C. Gauthier, P. Monzo, T. Gonzalez, A. Doye, A. Oldani, P. Gounon, V. Ricci, M. Cormont, and P. Boquet Early endosomes associated with dynamic F-actin structures are required for late trafficking of H. pylori VacA toxin J. Cell Biol., April 23, 2007; 177(2): 343 - 354. [Abstract] [Full Text] [PDF]