Alix/AIP1 Antagonizes Epidermal Growth Factor Receptor Downregulation by the Cbl-SETA/CIN85 Complex

Schmidt, Mirko H. H.; Hoeller, Daniela; Yu, Jiuhong; Furnari, Frank B.; Cavenee, Webster K.; Đikić, Ivan; Bögler, Oliver

doi:10.1128/mcb.24.20.8981-8993.2004

Cited by 103 publications

(113 citation statements)

References 45 publications

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“…An alternative explanation comes from the observations that multivesicular endosomes contain more than one type of lumenal vesicles (Gillooly et al, 2000;Kobayashi et al, 2002;Sobo et al, 2007a), raising the possibility that some are involved in the transport of signaling receptors to the lysosomes, whereas others undergo fusion at the limiting membrane. If so, intralumenal mechanisms must control the fate of intralumenal vesicles, back-fusion or degradation, including perhaps LBPA via its effector Alix, because Alix knockdown inhibits back-fusion (Abrami et al, 2004;Le Blanc et al, 2005) but not EGF receptor degradation (Schmidt et al, 2004;Cabezas et al, 2005). In addition, it cannot be excluded that some signaling receptors are returned to the endosomelimiting membrane via back-fusion and then recaptured within newly formed vesicles, perhaps like the EGF receptor in our assay, a mechanism that may contribute to explain MAPK signaling from late endosomes (Teis et al, 2002;Taub et al, 2007).…”

Section: Discussionmentioning

confidence: 99%

In Vitro Budding of Intralumenal Vesicles into Late Endosomes Is Regulated by Alix and Tsg101

Falguières

Luyet

Bissig

et al. 2008

MBoC

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Endosomes along the degradation pathway leading to lysosomes accumulate membranes in their lumen and thus exhibit a characteristic multivesicular appearance. These lumenal membranes typically incorporate down-regulated EGF receptor destined for degradation, but the mechanisms that control their formation remain poorly characterized. Here, we describe a novel quantitative biochemical assay that reconstitutes the formation of lumenal vesicles within late endosomes in vitro. Vesicle budding into the endosome lumen was time-, temperature-, pH-, and energy-dependent and required cytosolic factors and endosome membrane components. Our light and electron microscopy analysis showed that the compartment supporting the budding process was accessible to endocytosed bulk tracers and EGF receptor. We also found that the EGF receptor became protected against trypsin in our assay, indicating that it was sorted into the intraendosomal vesicles that were formed in vitro. Our data show that the formation of intralumenal vesicles is ESCRT-dependent, because the process was inhibited by the K173Q dominant negative mutant of hVps4. Moreover, we find that the ESCRT-I subunit Tsg101 and its partner Alix control intralumenal vesicle formation, by acting as positive and negative regulators, respectively. We conclude that budding of the limiting membrane toward the late endosome lumen, which leads to the formation of intraendosomal vesicles, is controlled by the positive and negative functions of Tsg101 and Alix, respectively. INTRODUCTIONIn eukaryotic cells, molecules of the plasma membrane, ligands and solutes are internalized into early endosomes, from where they can be recycled back to the plasma membrane, transported to the trans-Golgi network, or targeted to late endosomes and lysosomes (Gruenberg, 2001;Maxfield and McGraw, 2004;Mayor and Pagano, 2007). The latter pathway is followed in particular by ubiquitinated signaling receptors that need to be down-regulated. These receptors are incorporated into invaginations of the early endosomal membrane that form within their lumen (Hurley and Emr, 2006), thus giving rise to nascent multivesicular bodies (MVBs) or endosomal carrier vesicles (ECVs; Gruenberg and Stenmark, 2004;Piper and Katzmann, 2007), which function as intermediates between early and late endosomes. Eventually, intralumenal vesicles are delivered to lysosomes, where they are degraded together with their receptor cargo.Major progress has been made in our understanding of the molecular mechanisms that control the sorting of ubiquitinated receptors, in particular the epidermal growth factor (EGF) receptor (Hurley and Emr, 2006;Slagsvold et al., 2006;Piper and Katzmann, 2007;Williams and Urbe, 2007). These receptors interact via the ubiquitin moiety with hepatocyte growth factor-regulated tyrosine kinase substrate (Hrs), which in turn binds clathrin and phosphatidyl-inositol-3-phosphate (PtdIns3P), thereby concentrating the receptor in early endosomal membrane domains (Raiborg et al., 2001;Urbe et al., 2003;Raiborg et al., ...

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Section: Discussionmentioning

confidence: 99%

In Vitro Budding of Intralumenal Vesicles into Late Endosomes Is Regulated by Alix and Tsg101

Falguières

Luyet

Bissig

et al. 2008

MBoC

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“…In both cases, ALIX inhibits the ubiquitination of the receptor, and in the case of the EGF-R, also the ubiquitination of CBL. 32,33 However, in the case of the PDGF-R, ALIX stimulates the phosphorylation and proteasomal degradation of c-CBL. 33 What causes these differential effects of ALIX is currently unknown, but it might be dependent on the composition of the complex or the nature of the stimulus.…”

Section: Degradation Of Ligases Via Self-catalyzed Ubiquitinationmentioning

confidence: 99%

Ubiquitination of E3 ligases: self-regulation of the ubiquitin system via proteolytic and non-proteolytic mechanisms

2011

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Ubiquitin modification of many cellular proteins targets them for proteasomal degradation, but in addition can also serve non-proteolytic functions. Over the last years, a significant progress has been made in our understanding of how modification of the substrates of the ubiquitin system is regulated. However, little is known on how the ubiquitin system that is comprised of B1500 components is regulated. Here, we discuss how the biggest subfamily within the system, that of the E3 ubiquitin ligases that endow the system with its high specificity towards the numerous substrates, is regulated and in particular via self-regulation mediated by ubiquitin modification. Ligases can be targeted for degradation in a self-catalyzed manner, or through modification mediated by an external ligase(s). In addition, non-proteolytic functions of self-ubiquitination, for example activation of the ligase, of E3s are discussed. Cell Death and Differentiation (2011) 18, 1393-1402 doi:10.1038/cdd.2011; published online 4 March 2011One of the major roles of the covalent modification of cellular proteins by ubiquitin is signaling them for proteasomal degradation ( Figure 1). The first step of the modification is catalyzed by the ubiquitin-activating enzyme, E1, which generates a high-energy thiol ester intermediate that is subsequently transferred to the second enzyme, a ubiquitinconjugating enzyme, E2. The third step ascertains substrate specificity, and is catalyzed by one of the numerous (B650) ubiquitin ligases, E3s. Typically, it results in the formation of an isopeptide bond between the C-terminal Gly of ubiquitin and an e-NH 2 group of an internal Lys of the substrate. Less frequently, it can generate a linear peptide bond with the a-NH 2 group, a thiol ester bond with an internal Cys, or an ester bond with a Thr or Ser. The three-step cascade of reactions is repeated, where additional ubiquitin moieties are attached sequentially to one another in an isopeptide bond involving one of the seven internal Lys residues in the ubiquitin moiety, thus generating a polyubiquitin chain. Lys48-based chains serve as a signal for proteasomal degradation, whereas chains based on other internal Lys residues, or modification by single moiety(ies) can serve non-proteolytic functions.Ligases fall into two main families: RING (really interesting new gene) and HECT (homologous to the E6-AP carboxy terminus) domain-containing E3s. RING ligases serve as scaffolds that facilitate direct transfer of ubiquitin from the E2 to the target protein. HECT E3s contain an active Cys residue to which ubiquitin binds prior to its transfer to the substrate (Figure 1). There are B600 RING finger and B30 HECT ligases in humans. Smaller families of ligases (U-box, plant homology domain, and zinc finger) have also been described.An important problem relates to regulation of the ubiquitin system components, and in particular to that of the ligases that are the specific substrate-recognizing elements. 1,2 Phosphorylation of an E3 can activate the protein, such as the ca...

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“…6A). Pdcd-6͞Alg-2 forms a complex with CIN85͞SETA [Casitas B-lineage (Cbl)-interacting protein of 85 kDa͞SH3-domain encoding, expressed in tumorigenic astrocytes] and AIP1͞Alix, and they, in turn, bind Cbl and EGFR (26,27). AIP1͞Alix inhibited EGFR internalization and degradation; therefore, we hypothesize that Pdcd-6͞Alg-2 protects Her2 from Cbl-mediated degradation.…”

Section: Her2mentioning

confidence: 99%

Phosphoproteomic analysis of Her2/neu signaling and inhibition

Bose¹,

Molina²,

Patterson³

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

193

175

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Her2͞neu (Her2) is a tyrosine kinase belonging to the EGF receptor (EGFR)͞ErbB family and is overexpressed in 20 -30% of human breast cancers. We sought to characterize Her2 signal transduction pathways further by using MS-based quantitative proteomics. Stably transfected cell lines overexpressing Her2 or empty vector were generated, and the effect of an EGFR and Her2 selective tyrosine kinase inhibitor, PD168393, on these cells was characterized. Quantitative measurements were obtained on 462 proteins by using the SILAC (stable isotope labeling with amino acids in cell culture) method to monitor three conditions simultaneously. Of these proteins, 198 showed a significant increase in tyrosine phosphorylation in Her2-overexpressing cells, and 81 showed a significant decrease in phosphorylation. Treatment of Her2-overexpressing cells with PD168393 showed rapid reversibility of the majority of the Her2-triggered phosphorylation events. Phosphoproteins that were identified included many known Her2 signaling molecules as well as known EGFR signaling proteins that had not been previously linked to Her2, such as Stat1, Dok1, and ␦-catenin. Importantly, several previously uncharacterized Her2 signaling proteins were identified, including Axl tyrosine kinase, the adaptor protein Fyb, and the calcium-binding protein Pdcd-6͞Alg-2. We also identified a phosphorylation site in Her2, Y877, which is located in the activation loop of the kinase domain, is distinct from the known C-terminal tail autophosphorylation sites, and may have important implications for regulation of Her2 signaling. Network modeling, which combined phosphoproteomic results with literature-curated protein-protein interaction data, was used to suggest roles for some of the previously unidentified Her2 signaling proteins.breast cancer ͉ cellular networks ͉ proteomics ͉ signal transduction ͉ tyrosine kinase inhibitors

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Alix/AIP1 Antagonizes Epidermal Growth Factor Receptor Downregulation by the Cbl-SETA/CIN85 Complex

Cited by 103 publications

References 45 publications

In Vitro Budding of Intralumenal Vesicles into Late Endosomes Is Regulated by Alix and Tsg101

In Vitro Budding of Intralumenal Vesicles into Late Endosomes Is Regulated by Alix and Tsg101

Ubiquitination of E3 ligases: self-regulation of the ubiquitin system via proteolytic and non-proteolytic mechanisms

Phosphoproteomic analysis of Her2/neu signaling and inhibition

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