A conserved and regulated mechanism drives endosomal Rab transition

There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

Abstract

Endosomes and lysosomes harbor Rab5 and Rab7 on their surface as key proteins involved in their identity, biogenesis, and fusion. Rab activation requires a guanine nucleotide exchange factor (GEF), which is Mon1-Ccz1 for Rab7. During endosome maturation, Rab5 is replaced by Rab7, though the underlying mechanism remains poorly understood. Here, we identify the molecular determinants for Rab conversion in vivo and in vitro, and reconstitute Rab7 activation with yeast and metazoan proteins. We show (i) that Mon1-Ccz1 is an effector of Rab5, (ii) that membrane-bound Rab5 is the key factor to directly promote Mon1-Ccz1 dependent Rab7 activation and Rab7-dependent membrane fusion, and (iii) that this process is regulated in yeast by the casein kinase Yck3, which phosphorylates Mon1 and blocks Rab5 binding. Our study thus uncovers the minimal feed-forward machinery of the endosomal Rab cascade and a novel regulatory mechanism controlling this pathway.

Related collections

Most cited references 49

Record: found
Abstract: found
Article: not found

A new vital stain for visualizing vacuolar membrane dynamics and endocytosis in yeast

SD Emr (1995)

We have used a lipophilic styryl dye, N-(3-triethylammoniumpropyl)-4- (p-diethylaminophenyl-hexatrienyl) pyridinium dibromide (FM 4-64), as a vital stain to follow bulk membrane-internalization and transport to the vacuole in yeast. After treatment for 60 min at 30 degrees C, FM 4- 64 stained the vacuole membrane (ring staining pattern). FM 4-64 did not appear to reach the vacuole by passive diffusion because at 0 degree C it exclusively stained the plasma membrane (PM). The PM staining decreased after warming cells to 25 degrees C and small punctate structures became apparent in the cytoplasm within 5-10 min. After an additional 20-40 min, the PM and cytoplasmic punctate staining disappeared concomitant with staining of the vacuolar membrane. Under steady state conditions, FM 4-64 staining was specific for vacuolar membranes; other membrane structures were not stained. The dye served as a sensitive reporter of vacuolar dynamics, detecting such events as segregation structure formation during mitosis, vacuole fission/fusion events, and vacuolar morphology in different classes of vacuolar protein sorting (vps) mutants. A particularly striking pattern was observed in class E mutants (e.g., vps27) where 500-700 nm organelles (presumptive prevacuolar compartments) were intensely stained with FM 4- 64 while the vacuole membrane was weakly fluorescent. Internalization of FM 4-64 at 15 degrees C delayed vacuolar labeling and trapped FM 4- 64 in cytoplasmic intermediates between the PM and the vacuole. The intermediate structures in the cytoplasm are likely to be endosomes as their staining was temperature, time, and energy dependent. Interestingly, unlike Lucifer yellow uptake, vacuolar labeling by FM 4- 64 was not blocked in sec18, sec14, end3, and end4 mutants, but was blocked in sec1 mutant cells. Finally, using permeabilized yeast spheroplasts to reconstitute FM 4-64 transport, we found that delivery of FM 4-64 from the endosome-like intermediate compartment (labeled at 15 degrees C) to the vacuole was ATP and cytosol dependent. Thus, we show that FM 4-64 is a new vital stain for the vacuolar membrane, a marker for endocytic intermediates, and a fluor for detecting endosome to vacuole membrane transport in vitro.

0 comments Cited 271 times – based on 0 reviews      Review now

Record: found
Abstract: found
Article: not found

PLEKHM1 regulates autophagosome-lysosome fusion through HOPS complex and LC3/GABARAP proteins.

David G McEwan, Doris Popovic, Andrea Gubas … (2015)

The lysosome is the final destination for degradation of endocytic cargo, plasma membrane constituents, and intracellular components sequestered by macroautophagy. Fusion of endosomes and autophagosomes with the lysosome depends on the GTPase Rab7 and the homotypic fusion and protein sorting (HOPS) complex, but adaptor proteins that link endocytic and autophagy pathways with lysosomes are poorly characterized. Herein, we show that Pleckstrin homology domain containing protein family member 1 (PLEKHM1) directly interacts with HOPS complex and contains a LC3-interacting region (LIR) that mediates its binding to autophagosomal membranes. Depletion of PLEKHM1 blocks lysosomal degradation of endocytic (EGFR) cargo and enhances presentation of MHC class I molecules. Moreover, genetic loss of PLEKHM1 impedes autophagy flux upon mTOR inhibition and PLEKHM1 regulates clearance of protein aggregates in an autophagy- and LIR-dependent manner. PLEKHM1 is thus a multivalent endocytic adaptor involved in the lysosome fusion events controlling selective and nonselective autophagy pathways.

0 comments Cited 259 times – based on 0 reviews      Review now

Record: found
Abstract: found
Article: not found

Distinct Membrane Domains on Endosomes in the Recycling Pathway Visualized by Multicolor Imaging of Rab4, Rab5, and Rab11

Birte Sönnichsen, Stefano De Renzis, John Nielsen … (2000)

Two endosome populations involved in recycling of membranes and receptors to the plasma membrane have been described, the early and the recycling endosome. However, this distinction is mainly based on the flow of cargo molecules and the spatial distribution of these membranes within the cell. To get insights into the membrane organization of the recycling pathway, we have studied Rab4, Rab5, and Rab11, three regulatory components of the transport machinery. Following transferrin as cargo molecule and GFP-tagged Rab proteins we could show that cargo moves through distinct domains on endosomes. These domains are occupied by different Rab proteins, revealing compartmentalization within the same continuous membrane. Endosomes are comprised of multiple combinations of Rab4, Rab5, and Rab11 domains that are dynamic but do not significantly intermix over time. Three major populations were observed: one that contains only Rab5, a second with Rab4 and Rab5, and a third containing Rab4 and Rab11. These membrane domains display differential pharmacological sensitivity, reflecting their biochemical and functional diversity. We propose that endosomes are organized as a mosaic of different Rab domains created through the recruitment of specific effector proteins, which cooperatively act to generate a restricted environment on the membrane.

0 comments Cited 227 times – based on 0 reviews      Review now

All references

Author and article information

Contributors

Christian Ungermann:

ORCID: https://orcid.org/0000-0003-4331-8695

Suzanne R Pfeffer: Role: Senior Editor

Suzanne R Pfeffer: Role: Reviewing Editor

Journal

Journal ID (nlm-ta): eLife

Journal ID (iso-abbrev): Elife

Journal ID (publisher-id): eLife

Title: eLife

Publisher: eLife Sciences Publications, Ltd

ISSN (Electronic): 2050-084X

Publication date (Electronic, pub): 11 May 2020

Publication date Collection: 2020

Volume: 9

Electronic Location Identifier: e56090

Affiliations

[1 ]University of Osnabrück, Department of Biology/Chemistry, Biochemistry section OsnabrückGermany

[2 ]University of Münster, Institute of Biochemistry MünsterGermany

[3 ]University of Osnabrück, Center of Cellular Nanoanalytics (CellNanOs) OsnabrückGermany

Stanford University School of Medicine United States

Max Planck Institute of Molecular Cell Biology and Genetics Germany

Author information

Lars Langemeyer https://orcid.org/0000-0002-4309-0910

Daniel Kümmel http://orcid.org/0000-0003-3950-5914

Christian Ungermann https://orcid.org/0000-0003-4331-8695

Article

Publisher ID: 56090

DOI: 10.7554/eLife.56090

PMC ID: 7239660

PubMed ID: 32391792

SO-VID: cc4bbea6-0061-4288-b482-401e70a2391d

License:

This article is distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use and redistribution provided that the original author and source are credited.

History

Date received : 17 February 2020

Date accepted : 07 May 2020

Funding

Funded by: FundRef http://dx.doi.org/10.13039/501100001659, Deutsche Forschungsgemeinschaft;

Award ID: SFB 944

Award Recipient : Daniel Kümmel Christian Ungermann

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Custom metadata

Author impact statement Reconstitution of the endosomal Rab cascade reveals that Rab5 binds and activates the Mon1-Ccz1 guanine nucleotide exchange factor, which in turn recruits Rab7 to membranes to drive fusion.

ScienceOpen disciplines: Life sciences

Keywords: rab5,gef,endosome,rab cascade,rab7,mon1-ccz1,d. melanogaster,s. cerevisiae

Data availability:

ScienceOpen disciplines: Life sciences

Keywords: rab5, gef, endosome, rab cascade, rab7, mon1-ccz1, d. melanogaster, s. cerevisiae

A conserved and regulated mechanism drives endosomal Rab transition

Read this article at

Abstract

Related collections

Plant MYBs

Most cited references 49

A new vital stain for visualizing vacuolar membrane dynamics and endocytosis in yeast

PLEKHM1 regulates autophagosome-lysosome fusion through HOPS complex and LC3/GABARAP proteins.

Distinct Membrane Domains on Endosomes in the Recycling Pathway Visualized by Multicolor Imaging of Rab4, Rab5, and Rab11

Author and article information

Contributors

Journal

Affiliations

Author information

Article

History

Funding

Categories

Custom metadata

Comments

Comment on this article

Similar content 612

Cited by 38

Most referenced authors 1,192