Expression of Major Histocompatibility Complex Class II Molecules in HeLa Cells Promotes the Recruitment of AP-1 Golgi-specific Assembly Proteins on Golgi Membranes

doi:10.1074/jbc.271.48.30318

Expression of Major Histocompatibility Complex Class II Molecules in HeLa Cells Promotes the Recruitment of AP-1 Golgi-specific Assembly Proteins on Golgi Membranes*

From ^§ EMBL, Postfach 10-2209, Meyerhofstrasse 1, D-69012 Heidelberg, Germany and
^‡ UMR 144 CNRS- Institut Curie, Laboratoire “Mecanismes Moléculaires du Transport Intracellulaire, 12 rue Lhomond, 75005 Paris, France

^∥ To whom correspondence should be addressed: Tel.: 49-6221-387-285; Fax: 49-6221-387-306.

↵^¶ Present address (after 1-1-97): Institut de Biologie de Lille, CNRS IF 3, Institut Pasteur de Lille, 1 rue Professeur Calmette, 59019 Lille Cedex, France.

Abstract

The newly synthesized major histocompatibility complex (MHC) class II molecules, an αβ dimer associated with the Ii invariant chain, must be targeted to endosomal, lysosomal enzyme-rich compartments in order to bind and present immunogenic peptides. The precise route followed by this complex at the exit of the trans-Golgi network, the last sorting station of the biosynthetic pathway, is poorly understood. We show here that overexpression of αβIi complexes in HeLa cells promotes the first step of clathrin-coat assembly in vitro, that is the ARF-dependent translocation of AP-1 Golgi-specific assembly proteins on membranes. In contrast, αβ dimers alone or associated with Ii lacking most of its cytoplasmic domain fail to recruit AP-1. This study strongly suggests that the invariant chain (Ii) is responsible for the AP-1-dependent sorting of the αβ dimers in the trans-Golgi network of HeLa cells and that the MHC class II molecules are, like the mannose 6-phosphate receptors, transported directly from this compartment to endosomes via clathrin-coated vesicles.

Footnotes

↵* This work was supported in part by European Communities Grants Bio2-CT93-02205 and HCM ERB-CHRXCT-940592, grants from the association “Vaincre les Maladies Lysosomales” (to B. H.), and Grant 1405 from the Association de la Recherche contre le Cancer and grants from the Fondation pour la Recherche Médicale (to B. G.). The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
↵¹ The abbreviations used are:

MHC

major histocompatibility complex

MPR

mannose 6-phosphate receptor

TGN

trans-Golgi network

HA

emagglutinin

IGF

insulin-like growth factor

PAGE

polyacrylamide gel electrophoresis

GTPγ

guanosine 5′-3-O-(thio)triphosphate

mAb

monoclonal antibody.
- Received August 19, 1996.
- Revision received October 14, 1996.