Characterization of Multiple Multivesicular Body Sorting Determinants within Sna3: A Role for the Ubiquitin Ligase Rsp5

Oestreich, Andrea J.; Aboian, Mariam; Lee, Jacqueline; Azmi, Ishara F.; Payne, Johanna A.; Issaka, Rachel B.; Davies, Brian A.; Katzmann, David J.

doi:10.1091/mbc.e06-08-0680

Cited by 63 publications

(115 citation statements)

References 50 publications

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“…Sna3-GFP is degraded within the vacuole lumen subsequent to sorting into the MVB pathway; hence, its turnover serves as a measure of its MVB sorting (Oestreich et al, 2007). Consistent with microscopic analysis, loss of Mvb12 resulted in a decreased rate of turnover of Sna3-GFP ( Figure 3A and Supplemental Figure 2A).…”

Section: Identification Of Mvb12 As An Mvb Sorting Factorsupporting

confidence: 61%

“…To more quantitatively address the intermediate phenotype observed in mvb12⌬ cells, kinetic analysis of Sna3-GFP sorting was performed by pulse-chase analysis ( Figure 3A and Supplemental Figure 2A). Sna3-GFP is degraded within the vacuole lumen subsequent to sorting into the MVB pathway; hence, its turnover serves as a measure of its MVB sorting (Oestreich et al, 2007). Consistent with microscopic analysis, loss of Mvb12 resulted in a decreased rate of turnover of Sna3-GFP ( Figure 3A and Supplemental Figure 2A).…”

Section: Identification Of Mvb12 As An Mvb Sorting Factorsupporting

confidence: 61%

“…Sna3 sorting has been suggested to occur by a ubiquitin-independent process (Reggiori and Pelham, 2001). However, more recent observations indicate that Sna3 is ubiquitylated (Peng et al, 2003) and that both ubiquitindependent and ubiquitin-independent pathways can mediate Sna3 trafficking (Oestreich et al, 2007). Analysis of CPS, Ste2-GFP, and Ste3-GFP-Ub trafficking indicated that Mvb12 does not play an essential role in the general entry of ubiquitin-dependent MVB cargoes into the MVB pathway.…”

Section: Identification Of Mvb12 As An Mvb Sorting Factormentioning

confidence: 96%

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Mvb12 Is a Novel Member of ESCRT-I Involved in Cargo Selection by the Multivesicular Body Pathway

Oestreich

Davies

Payne

et al. 2007

MBoC

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The multivesicular body (MVB) sorting pathway impacts a variety of cellular functions in eukaryotic cells. Perhaps the best understood role for the MVB pathway is the degradation of transmembrane proteins within the lysosome. Regulation of cargo selection by this pathway is critically important for normal cell physiology, and recent advances in our understanding of this process have highlighted the endosomal sorting complexes required for transport (ESCRTs) as pivotal players in this reaction. To better understand the mechanisms of cargo selection during MVB sorting, we performed a genetic screen to identify novel factors required for cargo-specific selection by this pathway and identified the Mvb12 protein. Loss of Mvb12 function results in differential defects in the selection of MVB cargoes. A variety of analyses indicate that Mvb12 is a stable member of ESCRT-I, a heterologous complex involved in cargo selection by the MVB pathway. Phenotypes displayed upon loss of Mvb12 are distinct from those displayed by the previously described ESCRT-I subunits (vacuolar protein sorting 23, -28, and -37), suggesting a distinct function than these core subunits. These data support a model in which Mvb12 impacts the selection of MVB cargoes by modulating the cargo recognition capabilities of ESCRT-I. INTRODUCTIONThe endosomal system coordinates protein trafficking between various subcellular compartments, including the Golgi, plasma membrane, and lysosome. Cell surface proteins, including activated receptors, that have undergone endocytosis are typically recycled to the plasma membrane or targeted deeper into the endosomal pathway for degradation within the lysosome. Endosomal membrane proteins destined for the lumen of the lysosome undergo an additional sorting reaction during their inclusion into the multivesicular body (MVB) pathway (for review, see Gruenberg and Stenmark, 2004;Babst, 2005). MVBs form when the limiting membrane of the late endosome invaginates and buds into the lumen of the organelle, actively selecting a subset of the proteins from the limiting membrane in the process (Gorden et al., 1978;Haigler et al., 1979). The intralumenal vesicles within the MVB and their contents are exposed to hydrolases within the lysosome as a consequence of heterotypic fusion of these organelles. By contrast, proteins within the limiting membrane of the MVB are delivered to the limiting membrane of the lysosome/vacuole after heterotypic fusion (Odorizzi et al., 1998).Sorting of cargo into the MVB pathway and heterotypic fusion with the lysosme/vacuole leads to delivery into the hydrolytic lumen of the organelle, and therefore entry into this pathway must be highly regulated. Ubiquitination is the best-characterized cis-acting signal mediating entry into the MVB pathway (for reviews, see Katzmann et al., 2002;Hicke and Dunn, 2003;Raiborg et al., 2003). Studies in organisms ranging from the yeast Saccharomyces cerevisiae, to mammalian cells have demonstrated that ubiquitin modification of a variety of MVB cargoes is a requisit...

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Section: Identification Of Mvb12 As An Mvb Sorting Factorsupporting

confidence: 61%

Section: Identification Of Mvb12 As An Mvb Sorting Factorsupporting

confidence: 61%

Section: Identification Of Mvb12 As An Mvb Sorting Factormentioning

confidence: 96%

See 1 more Smart Citation

Mvb12 Is a Novel Member of ESCRT-I Involved in Cargo Selection by the Multivesicular Body Pathway

Oestreich

Davies

Payne

et al. 2007

MBoC

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“…Along these lines, recent studies show that Sna3 can utilize both ubiquitin-dependent and -independent mechanisms for its MVB targeting. Sna3 ubiquitination is dependent on Rsp5, but the function of Rsp5 is also critical for the MVB sorting of Sna3 independent of cargo ubiquitination (McNatt et al, 2007;Oestreich et al, 2007). Here we found that Ath1 has certain properties that are similar to Sna3.…”

Section: A New Signal For Protein Sorting Into Mvb Internal Vesiclesmentioning

confidence: 51%

“…Recent studies showed that Sna3 is also ubiquitinated; however, without ubiquitination it still can utilize an alternative mechanism, which involves the function of Rsp5, to be sorted into the MVB pathway (McNatt et al, 2007;Oestreich et al, 2007). Here we showed that the acid trehalase, Ath1, had the same transport behavior as Sna3.…”

Section: The Transmembrane Domain Of Ath1 Contains An Mvb Sorting Signalmentioning

confidence: 68%

The Transmembrane Domain of Acid Trehalase Mediates Ubiquitin-independent Multivesicular Body Pathway Sorting

Huang

Reggiori

Klionsky

2007

MBoC

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Trehalose serves as a storage source of carbon and plays important roles under various stress conditions. For example, in many organisms trehalose has a critical function in preserving membrane structure and fluidity during dehydration/ rehydration. In the yeast Saccharomyces cerevisiae, trehalose accumulates in the cell when the nutrient supply is limited but is rapidly degraded when the supply of nutrients is renewed. Hydrolysis of trehalose in yeast depends on neutral trehalase and acid trehalase (Ath1). Ath1 resides and functions in the vacuole; however, it appears to catalyze the hydrolysis of extracellular trehalose. Little is known about the transport route of Ath1 to the vacuole or how it encounters its substrate. Here, through the use of various trafficking mutants we showed that this hydrolase reaches its final destination through the multivesicular body (MVB) pathway. In contrast to the vast majority of proteins sorted into this pathway, Ath1 does not require ubiquitination for proper localization. Mutagenesis analyses aimed at identifying the unknown targeting signal revealed that the transmembrane domain of Ath1 contains the information sufficient for its selective sequestration into MVB internal vesicles. INTRODUCTIONTrehalose, a nonreducing disaccharide in which two glucose molecules are connected in an ␣-1,1-glycosidic linkage, was first found in the ergot of rye in 1832 (Kopp et al., 1993). This sugar is widely distributed in various organisms, including bacteria, fungi, plants, insects, and invertebrates (Elbein, 1974). It was originally believed that trehalose served only as a sugar and energy reserve in the cell; however, it is now known that this molecule also functions as a structural component, plays a role in transport, and is involved in signaling (Elbein et al., 2003). But the most significant function of trehalose is in providing membrane protection against different kinds of stress conditions, such as heat, freezing, dehydration, anoxia, and nutrient limitation (Crowe et al., 1984).Trehalose is quite common in yeast. In Saccharomyces cerevisiae, trehalose may constitute as much as 15-20% of its dry weight when growing in a stress environment. A strong correlation has been shown between trehalose content and stress resistance (Van Dijck et al., 1995). When yeast cells grow on rich carbon sources, they have a very low level of trehalose. In contrast, as they enter the stationary phase when nutrients are exhausted or during growth on nonfermentable carbon sources, the level of this disaccharide substantially increases. Conversely, when nutrients are resupplied, trehalose is rapidly mobilized (Nwaka and Holzer, 1998). The enzymes involved in synthesis and degradation of trehalose are the key regulators of these processes.Currently the best studied pathway of trehalose biosynthesis is the one that catalyzes UDP-glucose and glucose-6-phosphate into trehalose by trehalose-6-phosphate synthase and trehalose-phosphate-phosphatase activities (Thevelein, 1984). On the other hand, the degradation...

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Use of Proteome Arrays to Globally Identify Substrates for E3 Ubiquitin Ligases

Persaud

Rotin

2011

Methods in Molecular Biology

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Ubiquitin-protein ligases (E3s) are responsible for target recognition and subsequent modification of selected substrates within the ubiquitin proteasomal system (UPS). Substrates of this pathway are covalently modified by the attachment of ubiquitin usually onto Lys residues. As a result, these modified proteins can be targeted for degradation, endocytosis, protein sorting, subnuclear trafficking, or other fates. Despite the advancements in understanding the underlying mechanisms of the ubiquitin system, the substrates of most E3 enzymes remain largely unknown. Here, we describe the development of a high-throughput method to identify in vitro substrates for E3 ligases on a global proteomic scale. The enzymatic activity (ubiquitylation) and binding of ubiquitin ligases to their substrates are performed using protein (proteome) microarrays as the experimental platform, and using Nedd4/Rsp5 family members as examples of HECT E3 ligases. The in vitro ubiquitylation and binding substrates identified in these screens can provide invaluable insight into the cellular pathways in which E3 ligases participate.

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Characterization of Multiple Multivesicular Body Sorting Determinants within Sna3: A Role for the Ubiquitin Ligase Rsp5

Cited by 63 publications

References 50 publications

Mvb12 Is a Novel Member of ESCRT-I Involved in Cargo Selection by the Multivesicular Body Pathway

Mvb12 Is a Novel Member of ESCRT-I Involved in Cargo Selection by the Multivesicular Body Pathway

The Transmembrane Domain of Acid Trehalase Mediates Ubiquitin-independent Multivesicular Body Pathway Sorting

Use of Proteome Arrays to Globally Identify Substrates for E3 Ubiquitin Ligases

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