AGAP2 regulates retrograde transport between early endosomes and the TGN

Institut Curie - Centre de Recherche, Traffic, Signaling and Delivery Laboratory, 26 rue d'Ulm, 75248 Paris Cedex 05, France.
Journal of Cell Science (Impact Factor: 5.43). 07/2010; 123(Pt 14):2381-90. DOI: 10.1242/jcs.057778
Source: PubMed


The retrograde transport route links early endosomes and the TGN. Several endogenous and exogenous cargo proteins use this pathway, one of which is the well-explored bacterial Shiga toxin. ADP-ribosylation factors (Arfs) are approximately 20 kDa GTP-binding proteins that are required for protein traffic at the level of the Golgi complex and early endosomes. In this study, we expressed mutants and protein fragments that bind to Arf-GTP to show that Arf1, but not Arf6 is required for transport of Shiga toxin from early endosomes to the TGN. We depleted six Arf1-specific ARF-GTPase-activating proteins and identified AGAP2 as a crucial regulator of retrograde transport for Shiga toxin, cholera toxin and the endogenous proteins TGN46 and mannose 6-phosphate receptor. In AGAP2-depleted cells, Shiga toxin accumulates in transferrin-receptor-positive early endosomes, suggesting that AGAP2 functions in the very early steps of retrograde sorting. A number of other intracellular trafficking pathways are not affected under these conditions. These results establish that Arf1 and AGAP2 have key trafficking functions at the interface between early endosomes and the TGN.

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Available from: Yoko Shiba
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    • "Similarly, other, less well described sorting factors such as sorting nexin-17 (SNX17) (NPxY, NxxY, and NxxF sequences), EHD proteins (NPF motif ), and sorting nexin-27 (SNX27) (PDZ ligands) also contribute to plasma membrane recycling (Burden et al. 2004; Joubert et al. 2004; Braun et al. 2005; van Kerkhof et al. 2005). Endosome-to-TGN retrograde sorting is similarly complex, with contributions by clathrin in conjunction with AP1, PACS1, and epsinR (Meyer et al. 2000; Crump et al. 2001; Saint-Pol et al. 2004; Johannes and Popoff 2008; Shiba et al. 2010; Johannes and Wunder 2011). In addition, export of the mannose-6- phosphate receptor from the late endosome appears to be regulated by the TIP47/Rab9 assembly (Lombardi et al. 1993; Díaz and Pfeffer 1998; Carroll et al. 2001; also see Bulankina et al. 2009). "
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    ABSTRACT: The endosomal network comprises an interconnected network of membranous compartments whose primary function is to receive, dissociate, and sort cargo that originates from the plasma membrane and the biosynthetic pathway. A major challenge in cell biology is to achieve a thorough molecular description of how this network operates, and in so doing, how defects contribute to the etiology and pathology of human disease. We discuss the increasing body of evidence that implicates an ancient evolutionary conserved complex, termed "retromer," as a master conductor in the complex orchestration of multiple cargo-sorting events within the endosomal network.
    Preview · Article · Feb 2014 · Cold Spring Harbor perspectives in biology
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    • "ACAP2 localizes to REs in PC12 cells stimulated with nerve growth factor, and regulates the neurite outgrowth [30]. AGAP2 is required for the exit of Shiga toxin B subunit (STxB) from EEs in HeLa cells [31]. Combined with the previous findings, the current study postulates that a network of endosomal pathways into or out of REs can be regulated by a network of endosomal Arf GAPs. "
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    ABSTRACT: Retrograde transport is where proteins and lipids are transported back from the plasma membrane (PM) and endosomes to the Golgi, and crucial for a diverse range of cellular functions. Recycling endosomes (REs) serve as a sorting station for the retrograde transport and we recently identified evection-2, an RE protein with a pleckstrin homology (PH) domain, as an essential factor of this pathway. How evection-2 regulates retrograde transport from REs to the Golgi is not well understood. Here, we report that evection-2 binds to SMAP2, an Arf GTPase-activating protein. Endogenous SMAP2 localized mostly in REs and to a lesser extent, the trans-Golgi network (TGN). SMAP2 binds evection-2, and the RE localization of SMAP2 was abolished in cells depleted of evection-2. Knockdown of SMAP2, like that of evection-2, impaired the retrograde transport of cholera toxin B subunit (CTxB) from REs. These findings suggest that evection-2 recruits SMAP2 to REs, thereby regulating the retrograde transport of CTxB from REs to the Golgi.
    Full-text · Article · Jul 2013 · PLoS ONE
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    • "The same proteins were found immunoprecipitated with FLAG- Bcl10 using an anti-FLAG antibody in the FLAG-Bcl10-overex- pressing cells (Figure 6B). Interestingly, AP1 and EpsinR were shown to interact and regulate transport between early endosomes and the trans-Golgi network (TGN) (Hirst et al., 2003; Popoff et al., 2007; Shiba et al., 2010). Furthermore, we previously described that AP1 is recruited to nascent phagosomes and required for efficient phagocytic cup formation in macrophages (Braun et al., 2007). "
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    ABSTRACT: The protein Bcl10 contributes to adaptive and innate immunity through the assembly of a signaling complex that plays a key role in antigen receptor and FcR-induced NF-κB activation. Here we demonstrate that Bcl10 has an NF-κB-independent role in actin and membrane remodeling downstream of FcR in human macrophages. Depletion of Bcl10 impaired Rac1 and PI3K activation and led to an abortive phagocytic cup rich in PI(4,5)P(2), Cdc42, and F-actin, which could be rescued with low doses of F-actin depolymerizing drugs. Unexpectedly, we found Bcl10 in a complex with the clathrin adaptors AP1 and EpsinR. In particular, Bcl10 was required to locally deliver the vesicular OCRL phosphatase that regulates PI(4,5)P(2) and F-actin turnover, both crucial for the completion of phagosome closure. Thus, we identify Bcl10 as an early coordinator of NF-κB-mediated immune response with endosomal trafficking and signaling to F-actin remodeling.
    Full-text · Article · Nov 2012 · Developmental Cell
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