The Small G-protein Arf6GTP Recruits the AP-2 Adaptor Complex to Membranes

Paleotti, Olivia; Macia, Eric; Luton, Frédéric; Klein, Stéphanie; Partisani, Mariagrazia; Chardin, Pierre Teilhard de; Kirchhausen, Tom; Franco, Michel

doi:10.1074/jbc.m503099200

Cited by 106 publications

(96 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…AP-2 could function in this context to promote vesicle formation by recruiting proteins that induce membrane curvature, such as epsin (Chen et al, 1998;Ford et al, 2002), or BAR-domain-containing proteins, such as amphiphysin (David et al, 1996;Farsad et al, 2001;Peter et al, 2004;Slepnev et al, 2000). Consistent with this notion, previous studies have shown that Arf6 can bind to AP-2, and cooperate with phosphoinositides to promote AP-2 recruitment to liposomes (Paleotti et al, 2005). Alternatively, the reduced rate of MHCI internalization in AP-2-depleted cells could be indirect.…”

Section: Discussionsupporting

confidence: 62%

“…Recent work showed that Arf6 directly associates with AP-2 in a GTP-dependent manner, and that Arf6 functions cooperatively with PtdIns(4,5)P 2 to recruit AP-2 to membranes (Paleotti et al, 2005). This led the authors to conclude that the function of Arf6 in the context of clathrindependent endocytosis is to promote recruitment of AP-2 to the plasma membrane.…”

Section: Introductionmentioning

confidence: 88%

See 1 more Smart Citation

The adaptor complex AP-2 regulates post-endocytic trafficking through the non-clathrin Arf6-dependent endocytic pathway

Lau

Chou

2008

Journal of Cell Science

View full text Add to dashboard Cite

The ADP-ribosylation factor 6 (Arf6) GTPase functions as a key regulator of endocytic trafficking, participating in clathrin-independent endocytosis in most cell types. Unexpectedly, we found that siRNA-mediated depletion of clathrin or of adaptor protein 2 (AP-2)-complex subunits alters trafficking of Arf6 pathway cargo proteins, such as major histocompatibility complex class I (MHCI) and β1 integrin. Internalization of these cargoes from the plasma membrane was not affected in cells depleted of clathrin, but was modestly delayed in cells lacking AP-2. Furthermore, depletion of clathrin or AP-2 altered the intracellular distribution of MHCI and β1 integrin, inducing clustering in a perinuclear region. Despite this altered localization in both depleted populations, enhanced lysosomal targeting of MHCI was observed uniquely in cells that lack AP-2. Total levels of MHCI were modestly but consistently reduced in AP-2-depleted cells, and restored by the lysosomal inhibitor bafilomycin A. Furthermore, the half-life of surface-derived MHCI was reduced in AP-2-depleted cells. Consistent with enhanced degradative sorting, colocalization of Arf6 cargo with the late endosome and lysosome markers CD63 and Lamp1 was increased in cells depleted of AP-2 but not clathrin. These studies indicate a role for AP-2 in maintaining normal post-endocytic trafficking through the Arf6-regulated, non-clathrin pathway, and reveal pervasive effects of clathrin and AP-2 depletion on the endosomal and lysosomal system.

show abstract

Section: Discussionsupporting

confidence: 62%

Section: Introductionmentioning

confidence: 88%

The adaptor complex AP-2 regulates post-endocytic trafficking through the non-clathrin Arf6-dependent endocytic pathway

Lau

Chou

2008

Journal of Cell Science

View full text Add to dashboard Cite

show abstract

“…Arf6GTP may participate in clathrin coat assembly, by directly interacting with AP-2 and clathrin (Paleotti et al, 2005;Poupart et al, 2007) and by increasing the PI(4,5)P 2 level at the plasma membrane (Krauss et al, 2003). Consistently, depletion of Arf6 by siRNA affected the endocytosis of the b2AR.…”

Section: Discussionsupporting

confidence: 52%

“…Arf6 functions in both clathrin-dependent and -independent pathways of endocytosis of different membrane cargos such as transferrin receptor, polymeric immunoglobulin receptor, E-cadherin and MHC class I (Altschuler et al, 1999;D'Souza-Schorey et al, 1995;Klein et al, 2006;Palacios et al, 2002;Radhakrishna and Donaldson, 1997). By stimulating the PIP 2 synthesis (Krauss et al, 2003) and by directly interacting with AP-2 and clathrin (Paleotti et al, 2005;Poupart et al, 2007), Arf6 could induce the membrane recruitment of the coated-pit components. The effect of Arf6 on clathrin-mediated endocytosis was also proposed to be regulated by the Arf6-GAP SMAP1, which interacts directly with the clathrin light chain (Tanabe et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

Arf6 negatively controls the rapid recycling of the β2AR

Macia¹,

Partisani²,

Paleotti³

et al. 2012

Journal of Cell Science

View full text Add to dashboard Cite

Summary b2-adrenergic receptor (b2AR), a member of the GPCR (G-protein coupled receptor) family, is internalized in a ligand-and b-arrestindependent manner into early endosomes, and subsequently recycled back to the plasma membrane. Here, we report that b-arrestin promotes the activation of the small G protein Arf6, which regulates the recycling and degradation of b2AR. We demonstrate in vitro that the C-terminal region of b-arrestin1 interacts directly and simultaneously with Arf6GDP and its specific exchange factor EFA6, to promote Arf6 activation. Similarly, the ligand-mediated activation of b2AR leads to the formation of Arf6GTP in vivo in a b-arrestindependent manner. Expression of either EFA6 or an activated Arf6 mutant caused accumulation of b2AR in the degradation pathway. This phenotype could be rescued by the expression of an activated mutant of Rab4, suggesting that Arf6 acts upstream of Rab4. We propose a model in which Arf6 plays an essential role in b2AR desensitization. The ligand-mediated stimulation of b2AR relocates barrestin to the plasma membrane, and triggers the activation of Arf6 by EFA6. The activation of Arf6 leads to accumulation of b2AR in the degradation pathway, and negatively controls Rab4-dependent fast recycling to prevent the re-sensitization of b2AR.

show abstract

“…In contrast to ectopically expressed Arf6 in HeLa cells, endogenous Arf6 seems to mark the clathrin-dependent endocytic pathway in CHO cells (D'Souza-Schorey et al, 1995). Recently, studies have shown that Arf6 also plays a major role in clathrin-mediated endocytosis by directly controlling the assembly of the AP-2/clathrin coat (Paleotti et al, 2005;Tanabe et al, 2005). Arf6 has also been shown to be involved in recycling of endocytic membranes via the exocyst effector complex (Prigent et al, 2003).…”

Section: Arf6 Is Not a Specific Marker For Geecs In Cho Cellsmentioning

confidence: 99%

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

Kalia

Kumari

Chadda

et al. 2006

MBoC

106

117

View full text Add to dashboard Cite

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. INTRODUCTIONA cell uses multiple endocytic pathways for the uptake of molecules from the extracellular milieu (Mukherjee et al., 1997;Conner and Schmid, 2003). The better characterized pathways are mediated by clathrin-and caveolae-coated endocytic invaginations and require dynamin activity to be severed from the plasma membrane (Damke et al., 1994;Hinshaw and Schmid, 1995;Henley et al., 1998;Oh et al., 1998). There also seem to be one or more clathrin-independent pathways where dynamin is required, for example, the pathway for internalization of the interleukin (IL)-2 receptor subunits (Lamaze et al., 2001). In addition, there are a growing number of dynamin-independent endocytic processes that serve as internalization routes for a number of cell surface proteins, including lipid-linked proteins, such as GPI-anchored proteins (Lamaze and Schmid, 1995;Conner and Schmid, 2003;Nichols, 2003;Mayor and Riezman, 2004;Naslavsky et al., 2004;.GPI-anchored proteins are internalized via a dynamin, caveolin, and clathrin-independent pathway that is also responsible for the entry of a sizable fraction of the fluid phase in a number of cell types (Fivaz et al., 2002;Sabharanjak et al., 2002;Guha et al., 2003;. GPI-anchored proteins and the fluid phase enter the cell via tubular invaginations at the cell surface, into compartments termed GPI-anchored protein-enriched early endosomal compartments (GEECs) . At early times, these structures are largely devoid of cargo from the clathrin-dependent pathway. Besides a requirement for the small GTPase cdc42, very little is known about the molecular players that govern the formation and trafficking of GEECs. Much less is known about the detailed endocytic itinerary of these pathways (Lamaze and Schmid, 1995;Mayor and Riezman, 2004).After internalization...

show abstract

The Small G-protein Arf6GTP Recruits the AP-2 Adaptor Complex to Membranes

Cited by 106 publications

References 36 publications

The adaptor complex AP-2 regulates post-endocytic trafficking through the non-clathrin Arf6-dependent endocytic pathway

The adaptor complex AP-2 regulates post-endocytic trafficking through the non-clathrin Arf6-dependent endocytic pathway

Arf6 negatively controls the rapid recycling of the β2AR

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

Contact Info

Product

Resources

About