Mannose 6-phosphate receptors: new twists in the tale

Ghosh, Pradipta; Dahms, Nancy M.; Kornfeld, Stuart

doi:10.1038/nrm1050

Cited by 965 publications

(935 citation statements)

References 130 publications

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“…AP-1 is thought to participate in the transport of mannose-6-phosphate receptors (MPRs), which mediate sorting of acid hydrolases to lysosomes (reviewed by Ghosh et al, 2003). To rule out that the impairment of Nef-mediated degradation of CD4 in γ2 KD cells was due to a block in the delivery of acid hydrolases to lysosomes, we monitored lysosomal processing and secretion of the acid hydrolase cathepsin D (catD) by pulse-chase analysis.…”

Section: Resultsmentioning

confidence: 99%

CD4 downregulation by the HIV-1 protein Nef reveals distinct roles for the γ1 and γ2 subunits of the AP-1 complex in protein trafficking

Tavares

Silva

Silva-Januário

et al. 2017

Journal of Cell Science

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The HIV accessory protein Nef is a major determinant of viral pathogenesis that facilitates viral particle release, prevents viral antigen presentation and increases infectivity of new virus particles. These functions of Nef involve its ability to remove specific host proteins from the surface of infected cells, including the CD4 receptor. Nef binds to the adaptor protein 2 (AP-2) and CD4 in clathrin-coated pits, forcing CD4 internalization and its subsequent targeting to lysosomes. Herein, we report that this lysosomal targeting requires a variant of AP-1 containing isoform 2 of γ-adaptin (AP1G2, hereafter γ2). Depletion of the γ2 or μ1A (AP1M1) subunits of AP-1, but not of γ1 (AP1G1), precludes Nef-mediated lysosomal degradation of CD4. In γ2-depleted cells, CD4 internalized by Nef accumulates in early endosomes and this alleviates CD4 removal from the cell surface. Depletion of γ2 also hinders EGFR-EGF-complex targeting to lysosomes, an effect that is not observed upon γ1 depletion. Taken together, our data provide evidence that the presence of γ1 or γ2 subunits delineates two distinct variants of AP-1 complexes, with different functions in protein sorting.

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Section: Resultsmentioning

confidence: 99%

CD4 downregulation by the HIV-1 protein Nef reveals distinct roles for the γ1 and γ2 subunits of the AP-1 complex in protein trafficking

Tavares

Silva

Silva-Januário

et al. 2017

Journal of Cell Science

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“…isoforms, MPR46 [also called cation-dependent MPR (46 kDa)] and MPR300 [also called cation-independent MPR (300 kDa)], have been identified. (40) Based on these reports, we checked the involvement of MPRs in the RANKL trafficking pathway. However, treatment of HeLa cells with siRNA targeted to MPR46 and MPR300 did not affect RANKL transfer to the lysosomes under OPG coexpression conditions (data not shown).…”

Section: Discussionmentioning

confidence: 99%

Function of OPG as a traffic regulator for RANKL is crucial for controlled osteoclastogenesis

Aoki

Honma

Kariya

et al. 2010

Journal of Bone and Mineral Research

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The amount of the receptor activator of NF-kB ligand (RANKL) on the osteoblastic cell surface is considered to determine the magnitude of the signal input to osteoclast precursors and the degree of osteoclastogenesis. Previously, we have shown that RANKL is localized predominantly in lysosomal organelles, but little is found on the osteoblastic cell surface, and consequently, the regulated subcellular trafficking of RANKL in osteoblastic cells is important for controlled osteoclastogenesis. Here we have examined the involvement of osteoprotegerin (OPG), which is currently recognized as a decoy receptor for RANKL, in the regulation of RANKL behavior. It was suggested that OPG already makes a complex with RANKL in the Golgi apparatus and that the complex formation is necessary for RANKL sorting to the secretory lysosomes. It was also shown that each structural domain of OPG is indispensable for exerting OPG function as a traffic regulator. In particular, the latter domains of OPG, whose physiologic functions have been unclear, were indicated to sort RANKL molecules to lysosomes from the Golgi apparatus. In addition, the overexpression of RANK-OPG chimeric protein, which retained OPG function as a decoy receptor but lost the function as a traffic regulator, inhibited endogenous OPG function as a traffic regulator selectively in osteoblastic cells and resulted in the upregulation of osteoclastogenic ability despite the increased number of decoy receptor molecules. Conclusively, OPG function as a traffic regulator for RANKL is crucial for regulating osteoclastogenesis at least as well as that as a decoy receptor. ß

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“…We propose that the amoebic retromerlike complex is recruited to PPV and phagosomes by the specific interaction to GTPform EhRab7A, and involved, upon dissociation from EhRab7A, in the retrograde transport of not-yet-identified hydrolase receptor(s) from PPV and phagosomes to the Golgi apparatus. It has been shown in the mammalian system that trafficking of CI-MPR is also regulated by various proteins, i.e., AP-1, AP-2, GGA, PACS-1, and TIP47 (Ghosh et al, 2003). Among these adaptor proteins, TIP47 is involved in the retrieval of CI-MPR from late endosomes to the Golgi together with Rab9 (Carroll et al, 2001).…”

Section: Colocalization Of Ehrab7a and Ehvps26 By Immunofluorescence mentioning

confidence: 99%

A Retromerlike Complex Is a Novel Rab7 Effector That Is Involved in the Transport of the Virulence Factor Cysteine Protease in the Enteric Protozoan ParasiteEntamoeba histolytica

Nakada‐Tsukui

Saito‐Nakano

Ali

et al. 2005

MBoC

139

173

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Vesicular trafficking plays an important role in a virulence mechanism of the enteric protozoan parasite Entamoeba histolytica as secreted and lysosomal cysteine protease (CP) contributes to both cytolysis of tissues and degradation of internalized host cells. Despite the primary importance of intracellular sorting in pathogenesis, the molecular mechanism of CP trafficking remains largely unknown. In this report we demonstrate that transport of CP is regulated through a specific interaction of Rab7A small GTPase (EhRab7A) with the retromerlike complex. The amoebic retromerlike complex composed of Vps26, Vps29, and Vps35 was identified as EhRab7A-binding proteins. The amoebic retromerlike complex specifically bound to GTP-EhRab7A, but not GDP-EhRab7A through the direct binding via the carboxy terminus of EhVps26. In erythrophagocytosis the retromerlike complex was recruited to prephagosomal vacuoles, the unique preparatory vacuole of digestive enzymes, and later to phagosomes. This dynamism was indistinguishable from that of EhRab7A, and consistent with the premise that the retromerlike complex is involved in the retrograde transport of putative hydrolase receptor(s) from preparatory vacuoles and phagosomes to the Golgi apparatus. EhRab7A overexpression caused enlargement of lysosomes and decrease of the cellular CP activity. The reduced CP activity was restored by the coexpression of EhVps26, implying that the EhRab7A-mediated transport of CP to phagosomes is regulated by the retromerlike complex. INTRODUCTIONRab GTPases play an essential role to regulate intracellular membrane trafficking. The compartmentalization and functions of Rab proteins are modulated at multiple layers of mechanisms including isoprenylation of the carboxy terminus, nucleotide exchange, and binding of specific effector molecules (Stenmark and Olkkonen, 2001;Takai et al., 2001;Tuvim et al., 2001). Among these modulators, effectors play key roles in the control of 7-90 Rab proteins depending on organisms from fission yeast and amoeba to mammals and plants. A variety of effectors have been identified and shown to interact with specific Rab protein. For instance, regulatory secretions of neurotransmitters from neurons or insulin from pancreatic ␤-cells are regulated by the specific interaction of Rab3 with its effectors (Jahn and Sudhof, 1999). At least four proteins, Rabphilin3, Rim1, Rim2, and Noc2, are known to bind Rab3 and recruit cAMP-GEFII, 14 -3-3, and zyxin, respectively, to regulate cAMP responsiveness, phosphoserine-dependent signaling, and the interaction with cytoskeleton (Kotake et al., 1997;Ozaki et al., 2000;Sun et al., 2003). The specificity of the Rab-effector interaction is attributable to primary sequence motifs in only a few cases including exophilins or Slip/Slac2, Rab3, and Rab27 effectors (Izumi et al., 2003). However, the majority of Rab effectors lack recognizable conserved binding motifs. For instance, Rab5 effectors, rabaptin-5, Rabex-5, EEA1, Rabenosyn-5, hVps34/p150, p110␤/p35␣, rabip4Ј, and rabankyrin-5, which a...

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Mannose 6-phosphate receptors: new twists in the tale

Cited by 965 publications

References 130 publications

CD4 downregulation by the HIV-1 protein Nef reveals distinct roles for the γ1 and γ2 subunits of the AP-1 complex in protein trafficking

CD4 downregulation by the HIV-1 protein Nef reveals distinct roles for the γ1 and γ2 subunits of the AP-1 complex in protein trafficking

Function of OPG as a traffic regulator for RANKL is crucial for controlled osteoclastogenesis

A Retromerlike Complex Is a Novel Rab7 Effector That Is Involved in the Transport of the Virulence Factor Cysteine Protease in the Enteric Protozoan ParasiteEntamoeba histolytica

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