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.

Download full-text


Available from: Yoko Shiba,
  • Source
    • "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. "
    [Show abstract] [Hide abstract]
    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.
    PLoS ONE 07/2013; 8(7):e69145. DOI:10.1371/journal.pone.0069145 · 3.23 Impact Factor
  • Source
    • "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). "
    [Show abstract] [Hide abstract]
    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.
    Developmental Cell 11/2012; 23(5):954-67. DOI:10.1016/j.devcel.2012.09.021 · 9.71 Impact Factor
  • Source
    • "Moreover, PIKE-A overexpression redistributes AP1 from the perinuclear region to punctuate structure throughout the cells and decreases the transferring recycling (Nie et al. , 2005 ). As AP1 is responsible for proper synaptic endocytosis in neurons, it is tempting to speculate that PIKE-A also functions as a part of the coated vesicles during the endosomes-trans Golgi network transportation for neurotransmitters (Glyvuk et al. , 2010 ; Shiba et al. , 2010 ). Indirect evidence also suggests that PIKE-A might be involved in neurotransmitter release/uptake. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Since its discovery in 2000, phosphoinositide 3-kinase enhancer (PIKE) has been recognized as a class of GTPase that controls the enzymatic activities of phosphoinositide 3-kinase (PI3K) and Akt in the central nervous system (CNS). However, recent studies suggest that PIKEs are not only enhancers to PI3K/Akt but also modulators to other kinases including insulin receptor tyrosine kinase and focal adhesion kinases. Moreover, they regulate transcription factors such as signal transducer and activator of transcription and nuclear factor κB. Indeed, PIKE proteins participate in multiple cellular processes including control of cell survival, brain development, memory formation, gene transcription, and metabolism. In this review, we have summarized the functions of PIKE proteins in CNS and discussed their potential implications in various neurological disorders.
    Reviews in the neurosciences 04/2012; 23(2):153-61. DOI:10.1515/revneuro-2011-0066 · 3.33 Impact Factor
Show more