Sorting of activated epidermal growth factor receptor (EGFR) into intraluminal vesicles (ILVs) within the multivesicular body (MVB) is an essential step during the down-regulation of the receptor. The machinery that drives EGFR sorting attaches to the cytoplasmic face of the endosome and generates vesicles that bud into the endosome lumen, but somehow escapes encapsulation itself. This machinery is termed the ESCRT (endosomal sorting complexes required for transport) pathway, a series of multi-protein complexes and accessory factors first identified in yeast. Here, we review the yeast ESCRT pathway and describe the corresponding components in mammalian cells that sort EGFR. One of these is His domain protein tyrosine phosphatase (HD-PTP/PTPN23), and we review the interactions involving HD-PTP and ESCRTs. Finally, we describe a working model for how this ESCRT pathway might overcome the intrinsic topographical problem of EGFR sorting to the MVB lumen.

Introduction

Plasma membrane proteins govern how cells sense their environment, and therefore, the surface levels of many of these proteins are subject to strict control. A key device for exerting such control is the endocytic pathway, and of particular importance is determining the fate of internalised membrane proteins once they enter the early endosome. Some proteins return to the surface and hence retain their function. Others are ubiquitinated and then sorted into vesicles that bud into the endosome lumen (intraluminal vesicles; ILVs) to form the multivesicular body (MVB), an intermediate compartment en route to the degradative milieu of the lysosome (Figure 1).

MVB sorting.

Figure 1.
MVB sorting.

A crucial decision is made in the endosome. Internalised plasma membrane proteins either recycle or are ubiquitinated and sorted to the MVB.

Figure 1.
MVB sorting.

A crucial decision is made in the endosome. Internalised plasma membrane proteins either recycle or are ubiquitinated and sorted to the MVB.

MVB sorting affects a host of cellular activities, but its importance is exemplified by how it controls epidermal growth factor-mediated signalling. Ligand-activated epidermal growth factor receptor (EGFR/ErbB1) is ubiquitinated by Cbl ubiquitin ligase [1] and then sorted to the MVB and thus down-regulated to turn off the signalling response. Defective MVB sorting of EGFR and other growth factor receptors is linked to tumour formation and common diseases [26]. Here, we review the mechanisms underlying MVB sorting, notably of EGFR.

MVB sorting: endosomal sorting complexes required for transports

The molecular machinery that drives MVB sorting is termed the endosomal sorting complexes required for transport (ESCRT) pathway, a series of multi-protein complexes first identified in the yeast Saccharomyces cerevisiae (Table 1 and Figure 2). Deletion of ESCRT components in yeast causes gross changes to endosome morphology [7,8] and prevents ubiquitinated cargo from being sorted to the lumen of the vacuole [9].

The ESCRT pathway drives MVB formation in yeast.

Figure 2.
The ESCRT pathway drives MVB formation in yeast.

ESCRT complexes act in succession to facilitate the MVB sorting of ubiquitinated membrane proteins.

Figure 2.
The ESCRT pathway drives MVB formation in yeast.

ESCRT complexes act in succession to facilitate the MVB sorting of ubiquitinated membrane proteins.

Table 1
Conservation of ESCRTs
 Yeast protein/alternative name Human protein/alternative name 
ESCRT-0 Hse1 STAM1,2 
 Vps27 Hrs 
ESCRT-I Vps23/Stp22 TSG101/VPS23 
 Vps28 VPS28 
 Vps37 VPS37A,B,C,D 
 Mvb12 MVB12A,B; UBAP1 
ESCRT-II Vps22/Snf8 EAP30 
 Vps25 EAP20 
 Vps36 EAP45 
ESCRT-III Vps2/Did4 CHMP2A,B 
 Vps20 CHMP6 
 Vps24 CHMP3 
 Vps32/Snf7 CHMP4A,B,C 
VPS4 module Vps60 CHMP5 
 Vps46/Did2 CHMP1A,B 
 Vta1 VTA1 
 Vps4 VPS4A,B 
Accessory proteins Vps31/Bro1 Alix; HD-PTP 
 Doa4 UBPY/USP8 
 Yeast protein/alternative name Human protein/alternative name 
ESCRT-0 Hse1 STAM1,2 
 Vps27 Hrs 
ESCRT-I Vps23/Stp22 TSG101/VPS23 
 Vps28 VPS28 
 Vps37 VPS37A,B,C,D 
 Mvb12 MVB12A,B; UBAP1 
ESCRT-II Vps22/Snf8 EAP30 
 Vps25 EAP20 
 Vps36 EAP45 
ESCRT-III Vps2/Did4 CHMP2A,B 
 Vps20 CHMP6 
 Vps24 CHMP3 
 Vps32/Snf7 CHMP4A,B,C 
VPS4 module Vps60 CHMP5 
 Vps46/Did2 CHMP1A,B 
 Vta1 VTA1 
 Vps4 VPS4A,B 
Accessory proteins Vps31/Bro1 Alix; HD-PTP 
 Doa4 UBPY/USP8 

The yeast ESCRTs act sequentially (see Figure 2) [1012]. The pathway begins with ESCRT-0, a dimer of Vps27 (vacuolar protein sorting 27) and Hse1 [Hrs-binding protein, STAM (signal transducing adaptor molecule) and EAST 1 (EGFR-associated protein with SH3 and TAM domain 1)] [13]. The multiple ubiquitin-binding domains (UBDs) within ESCRT-0 collectively generate a high avidity ubiquitin-binding module to sequester MVB cargo within a sub-domain of the endosome-limiting membrane [14]. Cargo is thought to then transfer from ESCRT-0 to ESCRT-I [15] (composed of Vps23, Vps28, Vps37 and MVB12 [MVB protein of 12 kDa] subunits) [1618] and then on to ESCRT-II (comprising Vps36, Vps22 and two copies of Vps25) [1619] (see Figure 2). ESCRT-I and -II both bind ubiquitin [15,20] and form a ‘super-complex’ on the endosome surface [21,22]. To complete this potentially linear ESCRT assembly pathway [23], ESCRT-II recruits ESCRT-III via the ‘initiator’ ESCRT-III subunit, Vps20 [24] (Vps20 can also be recruited by the Vps28 subunit of ESCRT-I [25]). Vps20 then seeds the formation of a membrane-sculpting polymer of another ESCRT-III subunit, Vps32 (also termed Snf7) [2629]. Other ESCRT-III subunits (Vps2 and Vps24) then cap the polymer [28,29].

Aside from ESCRTs, other components are important for MVB formation. These include the accessory protein Vps31/Bro1 (Bck1-like resistance to osmotic shock 1) [30], which binds Vps32/Snf7 [31]; the deubiquitinase Doa4, which hydrolyses ubiquitin from cargo prior to completion of the ILV [32,33], and the VPS4 module [34]. This ATPase remodels, and ultimately disassembles, the ESCRT-III polymer to complete membrane scission and release monomeric ESCRT-III subunits back into the cytosol (see Figure 2).

ESCRTs and EGFR sorting to the MVB

These ESCRT pathway constituents are broadly conserved. However, multiple variants of several components exist in mammalian cells (Table 1). For example, for mammalian ESCRT-I, there are single genes for the VPS23 [also called TSG101 (tumour susceptibility gene 101)] and VPS28 subunits, but four variants of VPS37 (VPS37A–D) and three variants of MVB12 (MVB12A/B and UBAP1) [17]. Mammalian cells have several Bro1 variants, notably Alix (ALG-2 [apoptosis-linked gene 2] interacting protein X) and HD-PTP (His domain protein tyrosine phosphatase) [17]. Aside from MVB sorting, ESCRTs support other ‘reverse-topology’ membrane scission events in the cell, including viral budding, cytokinesis, and resealing of the plasma membrane and nuclear envelope [16,17]. Therefore, a major challenge has been to establish which ESCRTs act at the endosome during EGFR sorting. While a consensus has not fully emerged, EGFR appears to follow at least two parallel ESCRT pathways, each co-ordinated by a specific Bro1 protein and perhaps subject to distinct EGFR-dependent signalling networks.

Both Alix and HD-PTP share with yeast Bro1 an N-terminal Bro1 domain that harbours a conserved binding pocket for the C-terminus of CHMP4B (charged membrane protein/chromatin modifying protein 4B) [31] (the most abundant mammalian variant of Vps32/Snf7; Table 1), a coiled-coil domain (which in Alix adopts a V-shaped structure and is termed the V domain [35,36]) and a proline-rich region (PRR). In HD-PTP, the PRR is particularly extensive and is followed by a PTP domain and a PEST region [37]. The PTP domain has no readily observable catalytic activity towards model PTPase substrates [38], but displays PTPase activity towards FYN kinase [39].

Alix supports multiple ESCRT-mediated processes [40]. While some studies have found siRNA-mediated depletion of Alix without effect on ligand-dependent EGF/EGFR degradation [41,42], others have observed modest [43] or more striking [44] reduction. Interestingly, Alix depletion significantly inhibited the MVB sorting of EGFR activated by UV irradiation, but not EGFR activated by EGF [45]. It is presently unclear which ESCRTs work alongside Alix during MVB formation. However, VPS37B and VPS37C, but not VPS37A, form complexes with Alix via Alg-2, an endosomal Ca++-dependent regulator of Alix [46]. VPS37B and C each form ESCRT-I complexes with MVB12A/B, both of which have been implicated in EGFR down-regulation [47]. Hence, a subset of ESCRT-I complexes might work alongside Alg-2 and Alix to promote a Ca++-regulated EGFR sorting pathway.

Alix exists in the cytosol in an inactive conformation, in which the PRR is folded across the V domain and forms an auto-inhibitory interaction with the Bro1 domain (Figure 3). This ‘closed’ conformation holds the Bro1 and V domains against each other [48], preventing Alix from engaging CHMP4B, while also blocking a conserved FYx2L motif [35,36] within the V domain from accessing other effectors [49]. Several mechanisms activate membrane-associated Alix, by opening the V domain and helping to re-orientate it with respect to the Bro1 domain (Figure 3). These mechanisms include: binding of the TSG101 subunit of ESCRT-I to the PRR, or binding of Src to a cognate-binding site within the Bro1 domain, to displace the auto-inhibitory interaction [49]; phosphorylation of the PRR [50]; allosteric relief of the auto-inhibition via the binding of CEP55 (centrosomal protein of 55 kDa) or Alg-2 to distal sites within the PRR [51,52]; dimerisation of the V domain [53].

Alix is controlled by auto-inhibition and conformational change.

Figure 3.
Alix is controlled by auto-inhibition and conformational change.

Key binding sites within Alix Bro1 and V domains are made inaccessible by an auto-inhibitory interaction between the Bro1 domain and PRR. Several events, highlighted in red, open Alix to activate it.

Figure 3.
Alix is controlled by auto-inhibition and conformational change.

Key binding sites within Alix Bro1 and V domains are made inaccessible by an auto-inhibitory interaction between the Bro1 domain and PRR. Several events, highlighted in red, open Alix to activate it.

In contrast with the widespread cellular roles of Alix, HD-PTP acts selectively at the endosome and is essential for the forward movement of EGFR from the early endosome towards the lysosome. Its depletion causes a striking accumulation of tubulo-vesicular endosomal compartments that contain a build-up of ubiquitin–protein conjugates and reduces sorting of EGFR to the endosomal lumen [43,54]. Consistent with a function in EGFR trafficking, HD-PTP binds the EGFR adaptor Grb2, via the PRR [55]. The importance of HD-PTP for MVB sorting is highlighted by its necessity for the down-regulation of platelet-derived growth factor receptor [56] and α5β1 integrin [57], as well as MHC (major histocompatibility complex) class I targeted by the K3 ubiquitin ligase of Karposi's sarcoma-associated herpes virus [58]. Consistent with a role in receptor down-regulation, HD-PTP is a tumour suppressor [39,59,60] and HD-PTP haploinsufficiency is linked to a poor clinical prognosis [61].

HD-PTP works closely with ESCRT-0, and indeed is essential for releasing EGFR from ESCRT-0 and allowing it to engage ESCRT-III [54]. The ESCRT-0 subunit STAM2 (equivalent to yeast Hse1; see Table 1) binds directly to HD-PTP at two sites (Figure 4). Specifically, the STAM2 GAT (GGA and Tom1) domain binds at the CHMP4-binding pocket in the Bro1 domain [54,62], while the STAM2 SH3 domain binds to a peptide motif within the PRR [54]. An ESCRT-I complex, representing ∼10% of total ESCRT-I [63] and defined by the presence of UBAP1 (ubiquitin-associated protein 1) and VPS37A subunits, also co-operates closely with HD-PTP [63,64]. Consistent with their role in a specialised, endosome-specific ESCRT pathway [63], HD-PTP and UBAP1 are present in HeLa cells at relatively low copy number compared with several core ESCRT components including TSG101 and CHMP4B [65]. Like HD-PTP, UBAP1 is important for EGFR degradation and α5β1 integrin turnover [57,63], and is a candidate tumour suppressor [66,67]. Its C-terminal ubiquitin-binding region (SOUBA; solenoid of overlapping UBAs) [68] is essential for cargo trafficking [63]. UBAP1 binds to the conserved FYx2L motif within the coiled-coil domain of HD-PTP (Figure 4), but cannot bind Alix [69]. This binding selectivity is determined, in part, by the overall shape of each coiled-coil domain, which in HD-PTP adopts an open and extended conformation, and by local amino acid sequence differences within the respective FYx2L-binding pockets [69]. ESCRT-I also engages HD-PTP via TSG101 binding to the PRR [70], at a site that overlaps with that for the STAM2 SH3 domain [54]. The UBAP1-binding pocket is situated close by (Figure 4), so altogether the interactions of the ESCRT-0 SH3 domain and ESCRT-I with HD-PTP are most likely mutually exclusive.

HD-PTP acts as an open ESCRT-binding scaffold.

Figure 4.
HD-PTP acts as an open ESCRT-binding scaffold.

Model of the Bro1 and coiled-coil domains of HD-PTP based on crystal and solution structures, and extended to include the proximal region of the PRR. Bound UBAP1 and CHMP4B peptides are shown based on crystal structures.

Figure 4.
HD-PTP acts as an open ESCRT-binding scaffold.

Model of the Bro1 and coiled-coil domains of HD-PTP based on crystal and solution structures, and extended to include the proximal region of the PRR. Bound UBAP1 and CHMP4B peptides are shown based on crystal structures.

HD-PTP adopts an open, extended platform for ESCRT binding that appears not to be subject to the auto-inhibition that in Alix is overcome by large-scale conformational changes [71]. Instead, access of the CHMP4B C-terminus to the HD-PTP Bro1 domain is governed by competitive interactions that would be well suited to HD-PTP's role as a regulator of endosomal trafficking and its action in moving EGFR forward from ESCRT-0 towards ESCRT-III [54] (Figure 4). One obvious distinction in the crystal structures of the CHMP4B-binding pockets of Alix and HD-PTP is that the latter is partially occluded in the absence of ligand, consistent with a lower association rate [72]. Hence, binding of CHMP4B to the cytosolic form of HD-PTP may be intrinsically unfavourable. Furthermore, the CHMP4-binding site in HD-PTP can specifically accommodate STAM2, by virtue of the STAM2 GAT domain occupying the CHMP4B-binding pocket and extending towards a neighbouring binding pocket [62] (termed the specific pocket, or S-site [72]) that is absent from Alix [62,72]. Two endosomal proteins that control TGFβ family receptor signalling, SARA (Smad anchor for receptor activation) and endofin, also bind selectively to HD-PTP in competition with CHMP4B (Figure 4), with their N-terminal helices each fully occupying both the CHMP4B and S-site [72]. In summary, STAM2, SARA and endofin could potentially modulate the MVB sorting of multiple receptors by preventing HD-PTP from binding to CHMP4B. Meanwhile, their regulated release could conceivably leave an opened binding pocket into which the CHMP4B C-terminal peptide is then accepted. This binding switch may explain how HD-PTP moves EGFR from ESCRT-0 towards ESCRT-III [54].

A model for EGFR sorting

MVB sorting is conceptually challenging: ESCRTs attach to the cytoplasmic face of the endosome and sort cargo into vesicles that bud in the opposite direction, yet ESCRTs themselves somehow escape being packaged into the ILV. How might the HD-PTP pathway sort EGFR?

HD-PTP forms an open console on which ESCRTs can shuffle via competitive interactions (Figures 4 and 5A). ESCRT-0 [13] and ESCRT-I [73] are elongated complexes. Aligning them with HD-PTP according to their bi-dentate binding reactions reveals a striking polarity to the machinery: UBDs converge near where HD-PTP engages EGFR, while ESCRT-III-binding sites are ∼20–30 nm away (Figure 5A). Such polarity extends to include the deubiquitinase UBPY (Ub-protease Y, equivalent to yeast Doa4; Table 1), which binds to both CHMP4B and to the STAM SH3 domain [74], and supports HD-PTP-dependent EGFR sorting [54,75]. Overall, this arrangement is difficult to reconcile with a linear, end-over-end pathway. However, it fits a model in which an HD-PTP scaffold recruits ESCRTs sequentially to ubiquitinated EGFR (Figure 5B). We speculate that a radial arrangement of HD-PTP molecules around an EGFR-rich membrane domain would create a configuration capable of imposing curvature (Figure 5C). This assembly would simultaneously generate sites for ESCRT-III monomers to attach towards the rim of a forming vesicle, in readiness for well-ordered polymerisation (Figure 5C). In this scenario, UBPY, bound to ESCRT-III, should have sufficient reach to deubiquitinate EGFR and thus destabilise the structure, triggering ILV involution as a prelude to membrane scission.

Identifying a potential mechanism for EGFR sorting to the MVB.

Figure 5.
Identifying a potential mechanism for EGFR sorting to the MVB.

(A) Alignment shows the polarity of the MVB sorting machine. Key binding sites are shown in yellow. HD-PTP binding to EGFR may occur via Grb2, but other modes of interaction are possible. (B) Competitive binding reactions may explain how HD-PTP supports the sequential assembly of ESCRTs upon ubiquitinated EGFR. (C) A speculative model, in which these competitive binding reactions are superimposed onto the pathway of ILV formation. HD-PTP and ESCRT-0 attach to a core of ubiquitinated EGFR in a radial configuration. ESCRT-I integration helps expose ESCRT-III-binding sites towards the rim and may generate membrane curvature. From ESCRT-III, UBPY reaches cargo to destabilise the assembly. (D) Solving a topographical problem. Transport vesicle formation requires an exoskeleton (coat) (left). An ILV might use an ESCRT endoskeleton that is triggered to disassemble prior to membrane scission (right).

Figure 5.
Identifying a potential mechanism for EGFR sorting to the MVB.

(A) Alignment shows the polarity of the MVB sorting machine. Key binding sites are shown in yellow. HD-PTP binding to EGFR may occur via Grb2, but other modes of interaction are possible. (B) Competitive binding reactions may explain how HD-PTP supports the sequential assembly of ESCRTs upon ubiquitinated EGFR. (C) A speculative model, in which these competitive binding reactions are superimposed onto the pathway of ILV formation. HD-PTP and ESCRT-0 attach to a core of ubiquitinated EGFR in a radial configuration. ESCRT-I integration helps expose ESCRT-III-binding sites towards the rim and may generate membrane curvature. From ESCRT-III, UBPY reaches cargo to destabilise the assembly. (D) Solving a topographical problem. Transport vesicle formation requires an exoskeleton (coat) (left). An ILV might use an ESCRT endoskeleton that is triggered to disassemble prior to membrane scission (right).

In summary, while budding of transport vesicles into the cytoplasm requires an exoskeleton (i.e. a ‘coat’), we envisage that ILV formation might be driven by an endoskeleton that is triggered to disassemble prior to the neck closing (Figure 5D). Though speculative, this simple model reconciles key features of MVB sorting, including the ordered action of ESCRTs, without invoking large-scale movement of cargo or ESCRTs themselves. Moreover, it provides a route for the potentially highly damaging ESCRT-III polymer [76] to assemble in an ordered fashion from pre-positioned ESCRT-III monomers, towards the rim of a developing ILV. Such a location is optimal for triggering ESCRT-III polymerisation [77]. Furthermore, the C-terminal region of HD-PTP has an extended PRR containing multiple SH3-binding sites that bind Grb2 and potentially other SH3 domain signalling proteins, as well as an important PTPase domain [39]. It could thus engage an EGFR signalling core, consistent with the marked recruitment of HD-PTP to endosomes upon EGFR activation [78]. This may allow ESCRT assembly, and thus MVB sorting, to be coupled to the signalling status of EGFR, a prerequisite for carefully orchestrated receptor down-regulation. Finally, such an arrangement of ESCRTs may also be relevant for other reverse-topology membrane scission events.

Abbreviations

     
  • Alg-2

    apoptosis-linked gene 2

  •  
  • Alix

    ALG-2 interacting protein X

  •  
  • Bro1

    Bck1-like resistance to osmotic shock 1

  •  
  • CHMP

    charged membrane protein/chromatin modifying protein

  •  
  • EGFR

    epidermal growth factor receptor

  •  
  • ESCRT

    endosomal sorting complexes required for transport

  •  
  • GAT

    GGA and Tom1

  •  
  • Hse1

    Hrs-binding protein, STAM and EAST 1

  •  
  • ILV

    intraluminal vesicle

  •  
  • MVB

    multivesicular body

  •  
  • PRR

    proline-rich region

  •  
  • SARA

    Smad anchor for receptor activation

  •  
  • STAM

    signal transducing adaptor molecule

  •  
  • TSG101

    tumour susceptibility gene 101

  •  
  • UBD

    ubiquitin-binding domain

  •  
  • UBPY

    Ub-specific protease Y

  •  
  • Vps

    vacuolar protein sorting

Funding

This work is funded by the Medical Research Council [grant reference MR/K011049/1] and the Biotechnology and Biological Sciences Research Council [grant reference BB/K008773/1].

Competing Interests

The Authors declare that there are no competing interests associated with the manuscript.

References

References
1
Joazeiro
,
C.A.
,
Wing
,
S.S.
,
Huang
,
H.
,
Leverson
,
J.D.
,
Hunter
,
T.
and
Liu
,
Y.C.
(
1999
)
The tyrosine kinase negative regulator c-Cbl as a RING-type, E2-dependent ubiquitin-protein ligase
.
Science
286
,
309
312
2
Ceresa
,
B.P.
and
Peterson
,
J.L.
(
2014
)
Cell and molecular biology of epidermal growth factor receptor
.
Int. Rev. Cell Mol. Biol.
313
,
145
178
3
Mellman
,
I.
and
Yarden
,
Y.
(
2013
)
Endocytosis and cancer
.
Cold Spring Harb. Perspect. Biol.
5
,
a016949
4
Pines
,
G.
,
Köstler
,
W.J.
and
Yarden
,
Y.
(
2010
)
Oncogenic mutant forms of EGFR: lessons in signal transduction and targets for cancer therapy
.
FEBS Lett.
584
,
2699
2706
5
Tan
,
Y.H.
,
Krishnaswamy
,
S.
,
Nandi
,
S.
,
Kanteti
,
R.
,
Vora
,
S.
,
Onel
,
K.
et al. 
(
2010
)
CBL is frequently altered in lung cancers: its relationship to mutations in MET and EGFR tyrosine kinases
.
PLoS ONE
5
,
e8972
6
Tomas
,
A.
,
Futter
,
C.E.
and
Eden
,
E.R.
(
2014
)
EGF receptor trafficking: consequences for signaling and cancer
.
Trends Cell Biol.
24
,
26
34
7
Raymond
,
C.K.
,
Howald-Stevenson
,
I.
,
Vater
,
C.A.
and
Stevens
,
T.H.
(
1992
)
Morphological classification of the yeast vacuolar protein sorting mutants: evidence for a prevacuolar compartment in class E vps mutants
.
Mol. Biol. Cell
3
,
1389
1402
8
Rieder
,
S.E.
,
Banta
,
L.M.
,
Köhrer
,
K.
,
McCaffery
,
J.M.
and
Emr
,
S.D.
(
1996
)
Multilamellar endosome-like compartment accumulates in the yeast vps28 vacuolar protein sorting mutant
.
Mol. Biol. Cell
7
,
985
999
9
Odorizzi
,
G.
,
Babst
,
M.
and
Emr
,
S.D.
(
1998
)
Fab1p PtdIns(3)P 5-kinase function essential for protein sorting in the multivesicular body
.
Cell
95
,
847
858
10
Katzmann
,
D.J.
,
Odorizzi
,
G.
and
Emr
,
S.D.
(
2002
)
Receptor downregulation and multivesicular-body sorting
.
Nat. Rev. Mol. Cell Biol.
3
,
893
905
11
Hanson
,
P.I.
and
Cashikar
,
A.
(
2012
)
Multivesicular body morphogenesis
.
Annu. Rev. Cell Dev. Biol.
28
,
337
362
12
Frankel
,
E.B.
and
Audhya
,
A.
(
2018
)
ESCRT-dependent cargo sorting at multivesicular endosomes
.
Semin. Cell Dev. Biol.
74
,
4
10
13
Ren
,
X.
,
Kloer
,
D.P.
,
Kim
,
Y.C.
,
Ghirlando
,
R.
,
Saidi
,
L.F.
,
Hummer
,
G.
et al. 
(
2009
)
Hybrid structural model of the complete human ESCRT-0 complex
.
Structure
17
,
406
416
14
Ren
,
X.
and
Hurley
,
J.H.
(
2010
)
VHS domains of ESCRT-0 cooperate in high-avidity binding to polyubiquitinated cargo
.
EMBO J.
29
,
1045
1054
15
Katzmann
,
D.J.
,
Babst
,
M.
and
Emr
,
S.D.
(
2001
)
Ubiquitin-dependent sorting into the multivesicular body pathway requires the function of a conserved endosomal protein sorting complex, ESCRT-I
.
Cell
106
,
145
155
16
Christ
,
L.
,
Raiborg
,
C.
,
Wenzel
,
E.M.
,
Campsteijn
,
C.
and
Stenmark
,
H.
(
2017
)
Cellular functions and molecular mechanisms of the ESCRT membrane-scission machinery
.
Trends Biochem. Sci.
42
,
42
56
17
Hurley
,
J.H.
(
2015
)
ESCRTs are everywhere
.
EMBO J.
34
,
2398
2407
18
Schöneberg
,
J.
,
Lee
,
I.H.
,
Iwasa
,
J.H.
and
Hurley
,
J.H.
(
2017
)
Reverse-topology membrane scission by the ESCRT proteins
.
Nat. Rev. Mol. Cell Biol.
18
,
5
17
19
Babst
,
M.
,
Katzmann
,
D.J.
,
Synder
,
W.B.
,
Wendland
,
B.
and
Emr
,
S.D.
(
2002
)
Endosome-associated complex, ESCRT-II, recruits transport machinery for protein sorting at the multivesicular body
.
Dev. Cell
3
,
283
289
20
Alam
,
S.L.
,
Sun
,
J.
,
Payne
,
M.
,
Welch
,
B.D.
,
Blake
,
B.K.
,
Davis
,
D.R.
et al. 
(
2004
)
Ubiquitin interactions of NZF zinc fingers
.
EMBO J.
23
,
1411
1421
21
Gill
,
D.J.
,
Teo
,
H.
,
Sun
,
J.
,
Perisic
,
O.
,
Veprintsev
,
D.B.
,
Emr
,
S.D.
et al. 
(
2007
)
Structural insight into the ESCRT-I/-II link and its role in MVB trafficking
.
EMBO J.
26
,
600
612
22
Boura
,
E.
,
Różycki
,
B.
,
Chung
,
H.S.
,
Herrick
,
D.Z.
,
Canagarajah
,
B.
,
Cafiso
,
D.S.
et al. 
(
2012
)
Solution structure of the ESCRT-I and -II supercomplex: implications for membrane budding and scission
.
Structure
20
,
874
886
23
Babst
,
M.
,
Katzmann
,
D.J.
,
Estepa-Sabal
,
E.J.
,
Meerloo
,
T.
and
Emr
,
S.D.
(
2002
)
ESCRT-III: an endosome-associated heterooligomeric protein complex required for MVB sorting
.
Dev. Cell
3
,
271
282
24
Teis
,
D.
,
Saksena
,
S.
,
Judson
,
B.L.
and
Emr
,
S.D.
(
2010
)
ESCRT-II coordinates the assembly of ESCRT-III filaments for cargo sorting and multivesicular body vesicle formation
.
EMBO J.
29
,
871
883
25
Pineda-Molina
,
E.
,
Belrhali
,
H.
,
Piefer
,
A.J.
,
Akula
,
I.
,
Bates
,
P.
and
Weissenhorn
,
W.
(
2006
)
The crystal structure of the C-terminal domain of Vps28 reveals a conserved surface required for Vps20 recruitment
.
Traffic
7
,
1007
1016
26
Fyfe
,
I.
,
Schuh
,
A.L.
,
Edwardson
,
J.M.
and
Audhya
,
A.
(
2011
)
Association of the endosomal sorting complex ESCRT-II with the Vps20 subunit of ESCRT-III generates a curvature-sensitive complex capable of nucleating ESCRT-III filaments
.
J. Biol. Chem.
286
,
34262
34270
27
Teis
,
D.
,
Saksena
,
S.
and
Emr
,
S.D.
(
2008
)
Ordered assembly of the ESCRT-III complex on endosomes is required to sequester cargo during MVB formation
.
Dev. Cell
15
,
578
589
28
Saksena
,
S.
,
Wahlman
,
J.
,
Teis
,
D.
,
Johnson
,
A.E.
and
Emr
,
S.D.
(
2009
)
Functional reconstitution of ESCRT-III assembly and disassembly
.
Cell
136
,
97
109
29
Henne
,
W.M.
,
Stenmark
,
H.
and
Emr
,
S.D.
(
2013
)
Molecular mechanisms of the membrane sculpting ESCRT pathway
.
Cold Spring Harb. Perspect. Biol.
5
,
a016766
30
Odorizzi
,
G.
,
Katzmann
,
D.J.
,
Babst
,
M.
,
Audhya
,
A.
and
Emr
,
S.D.
(
2003
)
Bro1 is an endosome-associated protein that functions in the MVB pathway in Saccharomyces cerevisiae
.
J. Cell Sci.
116
,
1893
1903
31
Kim
,
J.
,
Sitaraman
,
S.
,
Hierro
,
A.
,
Beach
,
B.M.
,
Odorizzi
,
G.
and
Hurley
,
J.H.
(
2005
)
Structural basis for endosomal targeting by the Bro1 domain
.
Dev. Cell
8
,
937
947
32
Richter
,
C.
,
West
,
M.
and
Odorizzi
,
G.
(
2007
)
Dual mechanisms specify Doa4-mediated deubiquitination at multivesicular bodies
.
EMBO J.
26
,
2454
2464
33
Amerik
,
A.Y.
,
Nowak
,
J.
,
Swaminathan
,
S.
and
Hochstrasser
,
M.
(
2000
)
The Doa4 deubiquitinating enzyme is functionally linked to the vacuolar protein-sorting and endocytic pathways
.
Mol. Biol. Cell
11
,
3365
3380
34
Alonso
,
Y.A.M.
,
Migliano
,
S.M.
and
Teis
,
D.
(
2016
)
ESCRT-III and Vps4: a dynamic multipurpose tool for membrane budding and scission
.
FEBS J.
283
,
3288
3302
35
Lee
,
S.
,
Joshi
,
A.
,
Nagashima
,
K.
,
Freed
,
E.O.
and
Hurley
,
J.H.
(
2007
)
Structural basis for viral late-domain binding to Alix
.
Nat. Struct. Mol. Biol.
14
,
194
199
36
Fisher
,
R.D.
,
Chung
,
H.Y.
,
Zhai
,
Q.
,
Robinson
,
H.
,
Sundquist
,
W.I.
and
Hill
,
C.P.
(
2007
)
Structural and biochemical studies of ALIX/AIP1 and its role in retrovirus budding
.
Cell
128
,
841
852
37
Toyooka
,
S.
,
Ouchida
,
M.
,
Jitsumori
,
Y.
,
Tsukuda
,
K.
,
Sakai
,
A.
,
Nakamura
,
A.
et al. 
(
2000
)
HD-PTP: a novel protein tyrosine phosphatase gene on human chromosome 3p21.3
.
Biochem. Biophys. Res. Commun.
278
,
671
678
38
Gingras
,
M.C.
,
Kazan
,
J.M.
and
Pause
,
A.
(
2017
)
Role of ESCRT component HD-PTP/PTPN23 in cancer
.
Biochem. Soc. Trans.
45
,
845
854
39
Zhang
,
S.
,
Fan
,
G.
,
Hao
,
Y.
,
Hammell
,
M.
,
Wilkinson
,
J.E.
and
Tonks
,
N.K.
(
2017
)
Suppression of protein tyrosine phosphatase N23 predisposes to breast tumorigenesis via activation of FYN kinase
.
Genes Dev.
31
,
1939
1957
40
Bissig
,
C.
and
Gruenberg
,
J.
(
2014
)
ALIX and the multivesicular endosome: ALIX in Wonderland
.
Trends Cell Biol.
24
,
19
25
41
Bowers
,
K.
,
Piper
,
S.C.
,
Edeling
,
M.A.
,
Gray
,
S.R.
,
Owen
,
D.J.
,
Lehner
,
P.J.
et al. 
(
2006
)
Degradation of endocytosed epidermal growth factor and virally ubiquitinated major histocompatibility complex class I is independent of mammalian ESCRTII
.
J. Biol. Chem.
281
,
5094
5105
42
Cabezas
,
A.
,
Bache
,
K.G.
,
Brech
,
A.
and
Stenmark
,
H.
(
2005
)
Alix regulates cortical actin and the spatial distribution of endosomes
.
J. Cell Sci.
118
,
2625
2635
43
Doyotte
,
A.
,
Mironov
,
A.
,
McKenzie
,
E.
and
Woodman
,
P.
(
2008
)
The Bro1-related protein HD-PTP/PTPN23 is required for endosomal cargo sorting and multivesicular body morphogenesis
.
Proc. Natl Acad. Sci. U.S.A.
105
,
6308
6313
44
Sun
,
S.
,
Zhou
,
X.
,
Zhang
,
W.
,
Gallick
,
G.E.
and
Kuang
,
J.
(
2015
)
Unravelling the pivotal role of Alix in MVB sorting and silencing of the activated EGFR
.
Biochem. J.
466
,
475
487
45
Tomas
,
A.
,
Vaughan
,
S.O.
,
Burgoyne
,
T.
,
Sorkin
,
A.
,
Hartley
,
J.A.
,
Hochhauser
,
D.
et al. 
(
2015
)
WASH and Tsg101/ALIX-dependent diversion of stress-internalized EGFR from the canonical endocytic pathway
.
Nat. Commun.
6
,
7324
46
Okumura
,
M.
,
Katsuyama
,
A.M.
,
Shibata
,
H.
and
Maki
,
M.
(
2013
)
VPS37 isoforms differentially modulate the ternary complex formation of ALIX, ALG-2, and ESCRT-I
.
Biosci. Biotechnol. Biochem.
77
,
1715
1721
47
Tsunematsu
,
T.
,
Yamauchi
,
E.
,
Shibata
,
H.
,
Maki
,
M.
,
Ohta
,
T.
and
Konishi
,
H.
(
2010
)
Distinct functions of human MVB12A and MVB12B in the ESCRT-I dependent on their posttranslational modifications
.
Biochem. Biophys. Res. Commun.
399
,
232
237
48
Zhai
,
Q.
,
Landesman
,
M.B.
,
Chung
,
H.Y.
,
Dierkers
,
A.
,
Jeffries
,
C.M.
,
Trewhella
,
J.
et al. 
(
2011
)
Activation of the retroviral budding factor ALIX
.
J. Virol.
85
,
9222
9226
49
Zhou
,
X.
,
Si
,
J.
,
Corvera
,
J.
,
Gallick
,
G.E.
and
Kuang
,
J.
(
2010
)
Decoding the intrinsic mechanism that prohibits ALIX interaction with ESCRT and viral proteins
.
Biochem. J.
432
,
525
534
50
Sun
,
S.
,
Sun
,
L.
,
Zhou
,
X.
,
Wu
,
C.
,
Wang
,
R.
,
Lin
,
S.H.
et al. 
(
2016
)
Phosphorylation-dependent activation of the ESCRT function of ALIX in cytokinetic abscission and retroviral budding
.
Dev. Cell
36
,
331
343
51
Lee
,
H.H.
,
Elia
,
N.
,
Ghirlando
,
R.
,
Lippincott-Schwartz
,
J.
and
Hurley
,
J.H.
(
2008
)
Midbody targeting of the ESCRT machinery by a noncanonical coiled coil in CEP55
.
Science
322
,
576
580
52
Sun
,
S.
,
Zhou
,
X.
,
Corvera
,
J.
,
Gallick
,
G.E.
,
Lin
,
S.H.
and
Kuang
,
J.
(
2015
)
ALG-2 activates the MVB sorting function of ALIX through relieving its intramolecular interaction
.
Cell Discov.
1
,
15018
53
Pires
,
R.
,
Hartlieb
,
B.
,
Signor
,
L.
,
Schoehn
,
G.
,
Lata
,
S.
,
Roessle
,
M.
et al. 
(
2009
)
A crescent-shaped ALIX dimer targets ESCRT-III CHMP4 filaments
.
Structure
17
,
843
856
54
Ali
,
N.
,
Zhang
,
L.
,
Taylor
,
S.
,
Mironov
,
A.
,
Urbé
,
S.
and
Woodman
,
P.
(
2013
)
Recruitment of UBPY and ESCRT exchange drive HD-PTP-dependent sorting of EGFR to the MVB
.
Curr. Biol.
23
,
453
461
55
Tanase
,
C.A.
(
2010
)
Histidine domain-protein tyrosine phosphatase interacts with Grb2 and GrpL
.
PLoS ONE
5
,
e14339
56
Ma
,
H.
,
Wardega
,
P.
,
Mazaud
,
D.
,
Klosowska-Wardega
,
A.
,
Jurek
,
A.
,
Engström
,
U.
et al. 
(
2015
)
Histidine-domain-containing protein tyrosine phosphatase regulates platelet-derived growth factor receptor intracellular sorting and degradation
.
Cell. Signal.
27
,
2209
2219
57
Kharitidi
,
D.
,
Apaja
,
P.M.
,
Manteghi
,
S.
,
Suzuki
,
K.
,
Malitskaya
,
E.
,
Roldan
,
A.
et al. 
(
2015
)
Interplay of endosomal pH and ligand occupancy in integrin α5β1 ubiquitination, endocytic sorting, and cell migration
.
Cell Rep.
13
,
599
609
58
Parkinson
,
M.D.
,
Piper
,
S.C.
,
Bright
,
N.A.
,
Evans
,
J.L.
,
Boname
,
J.M.
,
Bowers
,
K.
et al. 
(
2015
)
A non-canonical ESCRT pathway, including histidine domain phosphotyrosine phosphatase (HD-PTP), is used for down-regulation of virally ubiquitinated MHC class I
.
Biochem. J.
471
,
79
88
59
Lin
,
G.
,
Aranda
,
V.
,
Muthuswamy
,
S.K.
and
Tonks
,
N.K.
(
2011
)
Identification of PTPN23 as a novel regulator of cell invasion in mammary epithelial cells from a loss-of-function screen of the ‘PTP-ome’
.
Genes Dev.
25
,
1412
1425
60
Tanaka
,
K.
,
Kondo
,
K.
,
Kitajima
,
K.
,
Muraoka
,
M.
,
Nozawa
,
A.
and
Hara
,
T.
(
2013
)
Tumor-suppressive function of protein-tyrosine phosphatase non-receptor type 23 in testicular germ cell tumors is lost upon overexpression of miR142-3p microRNA
.
J. Biol. Chem.
288
,
23990
23999
61
Manteghi
,
S.
,
Gingras
,
M.C.
,
Kharitidi
,
D.
,
Galarneau
,
L.
,
Marques
,
M.
,
Yan
,
M.
et al. 
(
2016
)
Haploinsufficiency of the ESCRT component HD-PTP predisposes to cancer
.
Cell Rep.
15
,
1893
1900
62
Lee
,
J.
,
Oh
,
K.J.
,
Lee
,
D.
,
Kim
,
B.Y.
,
Choi
,
J.S.
,
Ku
,
B.
et al. 
(
2016
)
Structural study of the HD-PTP Bro1 domain in a complex with the core region of STAM2, a subunit of ESCRT-0
.
PLoS ONE
11
,
e0149113
63
Stefani
,
F.
,
Zhang
,
L.
,
Taylor
,
S.
,
Donovan
,
J.
,
Rollinson
,
S.
,
Benion
,
J.
et al. 
(
2011
)
UBAP1 is a component of an endosome-specific ESCRT-I complex that is essential for MVB sorting
.
Curr. Biol.
21
,
1245
1250
64
Wunderley
,
L.
,
Brownhill
,
K.
,
Stefani
,
F.
,
Tabernero
,
L.
and
Woodman
,
P.
(
2014
)
The molecular basis for selective assembly of the UBAP1-containing endosome-specific ESCRT-I complex
.
J. Cell Sci.
127
(
Pt 3
),
663
672
65
Hein
,
M.Y.
,
Hubner
,
N.C.
,
Poser
,
I.
,
Cox
,
J.
,
Nagaraj
,
N.
,
Toyoda
,
Y.
et al. 
(
2015
)
A human interactome in three quantitative dimensions organized by stoichiometries and abundances
.
Cell
163
,
712
723
66
Wu
,
M.
,
Li
,
X.
,
Li
,
X.
and
Li
,
G.
(
2009
)
Signaling transduction network mediated by tumor suppressor/susceptibility genes in NPC
.
Curr. Genomics
10
,
216
222
67
Zhang
,
L.
,
Deng
,
T.
,
Li
,
X.
,
Liu
,
H.
,
Zhou
,
H.
,
Ma
,
J.
et al. 
(
2010
)
microRNA-141 is involved in a nasopharyngeal carcinoma-related genes network
.
Carcinogenesis
31
,
559
566
68
Agromayor
,
M.
,
Soler
,
N.
,
Caballe
,
A.
,
Kueck
,
T.
,
Freund
,
S.M.
,
Allen
,
M.D.
et al. 
(
2012
)
The UBAP1 subunit of ESCRT-I interacts with ubiquitin via a SOUBA domain
.
Structure
20
,
414
428
69
Gahloth
,
D.
,
Levy
,
C.
,
Heaven
,
G.
,
Stefani
,
F.
,
Wunderley
,
L.
,
Mould
,
P.
et al. 
(
2016
)
Structural basis for selective interaction between the ESCRT regulator HD-PTP and UBAP1
.
Structure
24
,
2115
2126
70
Ichioka
,
F.
,
Takaya
,
E.
,
Suzuki
,
H.
,
Kajigaya
,
S.
,
Buchman
,
V.L.
,
Shibata
,
H.
et al. 
(
2007
)
HD-PTP and Alix share some membrane-traffic related proteins that interact with their Bro1 domains or proline-rich regions
.
Arch. Biochem. Biophys.
457
,
142
149
71
Gahloth
,
D.
,
Heaven
,
G.
,
Jowitt
,
T.A.
,
Mould
,
A.P.
,
Bella
,
J.
,
Baldock
,
C.
et al. 
(
2017
)
The open architecture of HD-PTP phosphatase provides new insights into the mechanism of regulation of ESCRT function
.
Sci. Rep.
7
,
9151
72
Gahloth
,
D.
,
Levy
,
C.
,
Walker
,
L.
,
Wunderley
,
L.
,
Mould
,
A.P.
,
Taylor
,
S.
et al. 
(
2017
)
Structural basis for specific interaction of TGFβ signaling regulators SARA/Endofin with HD-PTP
.
Structure
25
,
1011
1024.e4
73
Boura
,
E.
,
Różycki
,
B.
,
Herrick
,
D.Z.
,
Chung
,
H.S.
,
Vecer
,
J.
,
Eaton
,
W.A.
et al. 
(
2011
)
Solution structure of the ESCRT-I complex by small angle X-ray scattering, EPR, and FRET spectroscopy
.
Proc. Natl Acad. Sci. U.S.A.
108
,
9437
9442
74
Row
,
P.E.
,
Liu
,
H.
,
Hayes
,
S.
,
Welchman
,
R.
,
Charalabous
,
P.
,
Hofmann
,
K.
et al. 
(
2007
)
The MIT domain of UBPY constitutes a CHMP binding and endosomal localization signal required for efficient epidermal growth factor receptor degradation
.
J. Biol. Chem.
282
,
30929
30937
75
Row
,
P.E.
,
Prior
,
I.A.
,
McCullough
,
J.
,
Clague
,
M.J.
and
Urbé
,
S.
(
2006
)
The ubiquitin isopeptidase UBPY regulates endosomal ubiquitin dynamics and is essential for receptor down-regulation
.
J. Biol. Chem.
281
,
12618
12624
76
Chiaruttini
,
N.
,
Redondo-Morata
,
L.
,
Colom
,
A.
,
Humbert
,
F.
,
Lenz
,
M.
,
Scheuring
,
S.
et al. 
(
2015
)
Relaxation of loaded ESCRT-III spiral springs drives membrane deformation
.
Cell
163
,
866
879
77
Lee
,
I.-H.
,
Kaib
,
H.
,
Carlsona
,
L.-A.
,
Groves
,
J.T.
and
Hurley
,
J.H.
(
2015
)
Negative membrane curvature catalyzes nucleation of endosomal sorting complex required for transport (ESCRT)-III assembly
.
Proc. Natl Acad. Sci. U.S.A.
112
,
15892
15897
78
Gosney
,
J.A.
,
Wilkey
,
D.W.
,
Merchant
,
M.L.
and
Ceresa
,
B.P.
(
2018
)
Proteomics reveals novel protein associations with early endosomes in an epidermal growth factor-dependent manner
.
J. Biol. Chem.
293
,
5895
5908
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