On the fate of early endosomes

2009 ◽  
Vol 390 (8) ◽  
Author(s):  
Anne Spang
Keyword(s):  
Molecular Mechanisms ◽  
Signaling Molecules ◽  
Early Endosome ◽  
Late Endosome ◽  
Late Endosomes ◽  
Early Endosomes ◽  
Logistic Problem ◽  
Intellectual Level ◽  
Intense Research

Abstract Proteins are endocytosed by various pathways into the cell. All these pathways converge at the level of the early endosome. The fate of the early endosome and how proteins are sorted into recycling and late endosomes/multi-vesicular body is a matter of debate and intense research. Obviously, the transition from early to late endosome poses an interesting logistic problem and would merit attention on an intellectual level. Numerous diseases are also caused by defects in turning off/over signaling molecules or mis-sorting of proteins at the level of the early endosome. This brief review aims to discuss different molecular mechanisms whereby early-to-late endosome transition could be achieved.

scholarly journals De novo formation of an early endosome during Rab5 to Rab7 transition

2020 ◽  
Author(s):  
Frode Miltzow Skjeldal ◽  
Linda Hofstad Haugen ◽  
Duarte Mateus ◽  
Dominik Frei ◽  
Oddmund Bakke
Keyword(s):  
De Novo ◽  
Early Endosome ◽  
Late Endosome ◽  
Second Phase ◽  
Specific Domain ◽  
Endosomal Membrane ◽  
Late Endosomes ◽  
Early Endosomes ◽  
Main Determinants ◽  
Insight Into

AbstractRab5 and Rab7a are the main determinants of early and late endosomes and are important regulators of endosomal progression. The transport from early endosomes to late endosome seems to be regulated through an endosomal maturation switch where Rab5 is exchanged with Rab7a on the same endosome. Here we provide new insight into the mechanism of endosomal maturation where we have discovered a stepwise Rab5 detachment, sequentially regulated by Rab7a. The initial detachment of Rab5 is Rab7a independent and demonstrate a diffusion-like exchange between cytosol and endosomal membrane, and the second phase is slower where Rab5 converges into a specific domain that specifically detaches as a Rab5 indigenous endosome. Consequently, we show that early endosomal maturation regulated through the Rab5 to Rab7a switch induce the formation of a new fully functional early endosome. Progression through a stepwise early endosomal maturation regulates the direction of the transport and concomitantly regulates the homeostasis of early endosomes.

scholarly journals Endosomal trafficking regulates receptor-mediated transcytosis of antibodies across the blood brain barrier

2017 ◽  
Vol 38 (4) ◽  
pp. 727-740 ◽  
Author(s):  
Arsalan S Haqqani ◽  
Christie E Delaney ◽  
Eric Brunette ◽  
Ewa Baumann ◽  
Graham K Farrington ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Blood Brain Barrier ◽  
Early Endosome ◽  
Brain Barrier ◽  
Endosomal Trafficking ◽  
Brain Endothelial Cells ◽  
Density Fractions ◽  
Blood Brain ◽  
Late Endosomes ◽  
Early Endosomes

Current methods for examining antibody trafficking are either non-quantitative such as immunocytochemistry or require antibody labeling with tracers. We have developed a multiplexed quantitative method for antibody ‘tracking’ in endosomal compartments of brain endothelial cells. Rat brain endothelial cells were co-incubated with blood-brain barrier (BBB)-crossing FC5, monovalent FC5Fc or bivalent FC5Fc fusion antibodies and control antibodies. Endosomes were separated using sucrose-density gradient ultracentrifugation and analyzed using multiplexed mass spectrometry to simultaneously quantify endosomal markers, receptor-mediated transcytosis (RMT) receptors and the co-incubated antibodies in each fraction. The quantitation showed that markers of early endosomes were enriched in high-density fractions (HDF), whereas markers of late endosomes and lysosomes were enriched in low-density fractions (LDF). RMT receptors, including transferrin receptor, showed a profile similar to that of early endosome markers. The in vitro BBB transcytosis rates of antibodies were directly proportional to their partition into early endosome fractions of brain endothelial cells. Addition of the Fc domain resulted in facilitated antibody ‘redistribution’ from LDF into HDF and additionally into multivesicular bodies (MVB). Sorting of various FC5 antibody formats away from late endosomes and lysosomes and into early endosomes and a subset of MVB results in increased antibody transcytosis at the abluminal side of the BBB.

scholarly journals Infectious bronchitis virus attaches to lipid rafts and enters cells via clathrin mediated endocytosis

2018 ◽  
Author(s):  
Huan Wang ◽  
Yingjie Sun ◽  
Xiang Mao ◽  
Chunchun Meng ◽  
Lei Tan ◽  
...  
Keyword(s):  
Lipid Rafts ◽  
Infectious Bronchitis Virus ◽  
Time Course ◽  
Molecular Mechanisms ◽  
Low Ph ◽  
Infection Process ◽  
Late Endosome ◽  
Poultry Industry ◽  
Infectious Bronchitis ◽  
Late Endosomes

ABSTRACTDue to its economic importance to in poultry industry, the biology and pathogenesis of infectious bronchitis virus (IBV) have been investigated extensively. However, the molecular mechanisms involved in IBV entry are not well characterized. In this study, systematic approaches were used to dissect IBV entry process in various susceptible cells. First, we observed that lipid rafts were involved in IBV attachment. Second, low pH in intracyplasmic vesicles was required for virus entry. By using the specific clathrin mediated endocytosis (CME) inhibitor or knock down of clathrin heavy chain (CHC), we demonstrated that IBV mainly utilized the CME for its entry. Furthermore, GTPase dynamin1 was involved in virus containing vesicle scission and internalization. Surprisingly, CME adaptor Eps15 had no effect on IBV internalization. Third, the penetration of IBV into cells led to active cytoskeleton rearrangement. After internalization, virus particles moved along with the classical endosome/lysosome track, as evidenced by co-localization of R18 labeled IBV with vehicle markers Rab5/Rab7/LAMP1 along with the infection time course. Functional inactivation of Rab5 and Rab7 significantly inhibited IBV infection. VCP, a protein helps early endosome maturation, was involved virus trafficking. Finally, by using the dual R18/DiOC labeled IBV, we observed that membrane fusion with late endosome/lysosome membranes was induced between 2-3 h.p.i.. Taken together, our findings demonstrate that IBV virions attach to lipid rafts and are internalized into cells via CME, move along with early/late endosomes-lysosomes, finally fuse with late endosome-lysosome membranes, release virus genome into cytoplasm. This study provides comprehensive images of IBV attachment-internalization-trafficking-fusion steps.IMPORTANCEIBV, the avian coronavirus isolated in 1937, infects chicken and causes economic loss in poultry industry. It has been reported that the entry of IBV requires low pH. However, the molecular mechanisms underlying IBV internalization and trafficking remain to be clarified. Therefore, we employed multiple chemical and molecular approaches to dissect the entry mechanisms of IBV in susceptible cells. Our results showed IBV entry was significantly inhibited when clathrin-mediated endocytosis (CME) was blocked by chemical inhibitor or depletion of clathrin protein. Moreover, by using R18-labeled IBV, we found that IBV particles attached to lipid rafts, led to actin rearrangement, and moved along with the entire endosomal system. R18/DiOC labeling method showed that IBV fused with late endosomes or lysosomes. This is the first report to describe the entire entry process of IBV, allowing for a better understanding of the infection process of group III avian coronavirus.

scholarly journals Rab5-mediated endosome formation is regulated at the trans-Golgi network

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Makoto Nagano ◽  
Junko Y. Toshima ◽  
Daria Elisabeth Siekhaus ◽  
Jiro Toshima
Keyword(s):  
Plasma Membrane ◽  
Early Endosome ◽  
Vesicle Transport ◽  
Nucleotide Exchange ◽  
Trafficking Pathway ◽  
Transport Vesicles ◽  
Late Endosomes ◽  
Early Endosomes ◽  
Critical Location ◽  
Golgi Network

AbstractEarly endosomes, also called sorting endosomes, are known to mature into late endosomes via the Rab5-mediated endolysosomal trafficking pathway. Thus, early endosome existence is thought to be maintained by the continual fusion of transport vesicles from the plasma membrane and the trans-Golgi network (TGN). Here we show instead that endocytosis is dispensable and post-Golgi vesicle transport is crucial for the formation of endosomes and the subsequent endolysosomal traffic regulated by yeast Rab5 Vps21p. Fittingly, all three proteins required for endosomal nucleotide exchange on Vps21p are first recruited to the TGN before transport to the endosome, namely the GEF Vps9p and the epsin-related adaptors Ent3/5p. The TGN recruitment of these components is distinctly controlled, with Vps9p appearing to require the Arf1p GTPase, and the Rab11s, Ypt31p/32p. These results provide a different view of endosome formation and identify the TGN as a critical location for regulating progress through the endolysosomal trafficking pathway.

scholarly journals Transport through the yeast endocytic pathway occurs through morphologically distinct compartments and requires an active secretory pathway and Sec18p/N-ethylmaleimide-sensitive fusion protein.

1997 ◽  
Vol 8 (1) ◽  
pp. 13-31 ◽  
Author(s):  
L Hicke ◽  
B Zanolari ◽  
M Pypaert ◽  
J Rohrer ◽  
H Riezman
Keyword(s):  
Fusion Protein ◽  
Secretory Pathway ◽  
Protein A ◽  
Brefeldin A ◽  
Early Endosome ◽  
Late Endosome ◽  
Endocytic Pathway ◽  
Early Secretory Pathway ◽  
Late Endosomes

Molecules travel through the yeast endocytic pathway from the cell surface to the lysosome-like vacuole by passing through two sequential intermediates. Immunofluorescent detection of an endocytosed pheromone receptor was used to morphologically identify these intermediates, the early and late endosomes. The early endosome is a peripheral organelle that is heterogeneous in appearance, whereas the late endosome is a large perivacuolar compartment that corresponds to the prevacuolar compartment previously shown to be an endocytic intermediate. We demonstrate that inhibiting transport through the early secretory pathway in sec mutants quickly impedes transport from the early endosome. Treatment of sensitive cells with brefeldin A also blocks transport from this compartment. We provide evidence that Sec18p/N-ethylmaleimide-sensitive fusion protein, a protein required for membrane fusion, is directly required in vivo for forward transport early in the endocytic pathway. Inhibiting protein synthesis does not affect transport from the early endosome but causes endocytosed proteins to accumulate in the late endosome. As newly synthesized proteins and the late steps of secretion are not required for early to late endosome transport, but endoplasmic reticulum through Golgi traffic is, we propose that efficient forward transport in the early endocytic pathway requires delivery of lipid from secretory organelles to endosomes.

scholarly journals Huntingtin–HAP40 complex is a novel Rab5 effector that regulates early endosome motility and is up-regulated in Huntington's disease

2006 ◽  
Vol 172 (4) ◽  
pp. 605-618 ◽  
Author(s):  
Arun Pal ◽  
Fedor Severin ◽  
Barbara Lommer ◽  
Anna Shevchenko ◽  
Marino Zerial
Keyword(s):  
Huntington's Disease ◽  
Huntington’S Disease ◽  
Actin Filaments ◽  
Molecular Mechanisms ◽  
Early Endosome ◽  
Drastic Reduction ◽  
Pathological Conditions ◽  
Early Endosomes ◽  
Guanosine Triphosphatase ◽  
Endocytic Activity

The molecular mechanisms underlying the targeting of Huntingtin (Htt) to endosomes and its multifaceted role in endocytosis are poorly understood. In this study, we have identified Htt-associated protein 40 (HAP40) as a novel effector of the small guanosine triphosphatase Rab5, a key regulator of endocytosis. HAP40 mediates the recruitment of Htt by Rab5 onto early endosomes. HAP40 overexpression caused a drastic reduction of early endosomal motility through their displacement from microtubules and preferential association with actin filaments. Remarkably, endogenous HAP40 was up-regulated in fibroblasts and brain tissue from human patients affected by Huntington's disease (HD) as well as in STHdhQ111 striatal cells established from a HD mouse model. These cells consistently displayed altered endosome motility and endocytic activity, which was restored by the ablation of HAP40. In revealing an unexpected link between Rab5, HAP40, and Htt, we uncovered a new mechanism regulating cytoskeleton-dependent endosome dynamics and its dysfunction under pathological conditions.

scholarly journals PxdA interacts with the DipA phosphatase to regulate endosomal hitchhiking of peroxisomes

2021 ◽  
pp. mbc.E20-08-0559
Author(s):  
John Salogiannis ◽  
Jenna R. Christensen ◽  
Livia D. Songster ◽  
Adriana Aguilar-Maldonado ◽  
Nandini Shukla ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Lipid Droplets ◽  
Molecular Mechanisms ◽  
Ustilago Maydis ◽  
Adaptor Proteins ◽  
Early Endosome ◽  
Alternative Mode ◽  
Ribonucleoprotein Complexes ◽  
Early Endosomes ◽  
Mode Of Transport

In canonical microtubule-based transport, adaptor proteins link cargos to dynein and kinesin motors. Recently, an alternative mode of transport known as ‘hitchhiking’ was discovered, where cargos achieve motility by hitching a ride on already-motile cargos, rather than attaching to a motor protein. Hitchhiking has been best-studied in two filamentous fungi, Aspergillus nidulans and Ustilago maydis. In U. maydis, ribonucleoprotein complexes, peroxisomes, lipid droplets, and endoplasmic reticulum hitchhike on early endosomes. In A. nidulans, peroxisomes hitchhike using a putative molecular linker, PxdA, which associates with early endosomes. However, whether other organelles use PxdA to hitchhike on early endosomes is unclear, as are the molecular mechanisms that regulate hitchhiking. Here we find that the proper distribution of lipid droplets, mitochondria and pre-autophagosomes do not require PxdA, suggesting that PxdA is a peroxisome-specific molecular linker. We identify two new pxdA alleles, including a point mutation (R2044P) that disrupts PxdA's ability to associate with early endosomes and reduces peroxisome movement. We also identify a novel regulator of peroxisome hitchhiking, the phosphatase DipA. DipA co-localizes with early endosomes and its early endosome-association relies on PxdA. Together, our data suggest that PxdA and the DipA phosphatase are specific regulators of peroxisome hitchhiking on early endosomes. [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text]

scholarly journals Mycobacterium's Arrest of Phagosome Maturation in Macrophages Requires Rab5 Activity and Accessibility to Iron

2003 ◽  
Vol 14 (8) ◽  
pp. 3366-3377 ◽  
Author(s):  
Victoria A. Kelley ◽  
Jeffrey S. Schorey
Keyword(s):  
Mycobacterium Avium ◽  
Dominant Negative ◽  
Late Endosome ◽  
Maturation Process ◽  
Phagosome Maturation ◽  
Retroviral Transduction ◽  
Murine Macrophages ◽  
Late Endosomes ◽  
Early Endosomes ◽  
Insight Into

Many mycobacteria are intramacrophage pathogens that reside within nonacidified phagosomes that fuse with early endosomes but do not mature to phagolysosomes. The mechanism by which mycobacteria block this maturation process remains elusive. To gain insight into whether fusion with early endosomes is required for mycobacteria-mediated inhibition of phagosome maturation, we investigated how perturbing the GTPase cycles of Rab5 and Rab7, GTPases that regulate early and late endosome fusion, respectively, would affect phagosome maturation. Retroviral transduction of the constitutively activated forms of both GTPases into primary murine macrophages had no effect on Mycobacterium avium retention in an early endosomal compartment. Interestingly, expression of dominant negative Rab5, Rab5(S34N), but not dominant negative Rab7, resulted in a significant increase in colocalization of M. avium with markers of late endosomes/lysosomes and increased mycobacterial killing. This colocalization was specific to mycobacteria since Rab5(S34N) expressing cells showed diminished trafficking of endocytic tracers to lysosomes. We further demonstrated that maturation of M. avium phagosomes was halted in Rab5(S34N) expressing macrophages supplemented with exogenous iron. These findings suggest that fusion with early endosomes is required for mycobacterial retention in early phagosomal compartments and that an inadequate supply of iron is one factor in mycobacteria's inability to prevent the normal maturation process in Rab5(S34N)-expressing macrophages.

scholarly journals Phosphatidylinositol 4-phosphate and phosphatidylinositol 3-phosphate regulate phagolysosome biogenesis

2015 ◽  
Vol 112 (15) ◽  
pp. 4636-4641 ◽  
Author(s):  
Andreas Jeschke ◽  
Nicole Zehethofer ◽  
Buko Lindner ◽  
Jessica Krupp ◽  
Dominik Schwudke ◽  
...  
Keyword(s):  
Early Endosome ◽  
Phagosome Maturation ◽  
Phagocytic Cells ◽  
Late Endosomes ◽  
Early Endosomes ◽  
Lipid Kinases ◽  
Phosphatidylinositol 4 ◽  
Endocytic Compartments ◽  
Late Stages ◽  
Phosphatidylinositol 3

Professional phagocytic cells ingest microbial intruders by engulfing them into phagosomes, which subsequently mature into microbicidal phagolysosomes. Phagosome maturation requires sequential fusion of the phagosome with early endosomes, late endosomes, and lysosomes. Although various phosphoinositides (PIPs) have been detected on phagosomes, it remained unclear which PIPs actually govern phagosome maturation. Here, we analyzed the involvement of PIPs in fusion of phagosomes with various endocytic compartments and identified phosphatidylinositol 4-phosphate [PI(4)P], phosphatidylinositol 3-phosphate [PI(3)P], and the lipid kinases that generate these PIPs, as mediators of phagosome–lysosome fusion. Phagosome–early endosome fusion required PI(3)P, yet did not depend on PI(4)P. Thus, PI(3)P regulates phagosome maturation at early and late stages, whereas PI(4)P is selectively required late in the pathway.

scholarly journals DRAM1 requires PI(3,5)P2 generation by PIKfyve to deliver vesicles and their cargo to endolysosomes

2020 ◽  
Author(s):  
Michiel van der Vaart ◽  
Adrianna Banducci-Karp ◽  
Gabriel Forn-Cuní ◽  
Philip M.M. Witt ◽  
Joost J. Willemse ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Transmembrane Protein ◽  
Vesicle Fusion ◽  
Multivesicular Bodies ◽  
Potential Therapeutic Target ◽  
Zebrafish Model ◽  
Lipid Kinase ◽  
Late Endosomes ◽  
Early Endosomes ◽  
Chemical Inhibition

Endolysosomal vesicle trafficking and autophagy are crucial degradative pathways in maintenance of cellular homeostasis. The transmembrane protein DRAM1 is a potential therapeutic target that primarily localises to endolysosomal vesicles and promotes autophagy and vesicle fusion with lysosomes. However, the molecular mechanisms underlying DRAM1-mediated vesicle fusion events remain unclear. Using high-resolution confocal microscopy in the zebrafish model, we show that mCherry-Dram1 labelled vesicles interact and fuse with early endosomes marked by PI(3)P. Following these fusion events, early endosomes mature into late endosomes in a process dependent on the conversion of PI(3)P into PI(3,5)P2 by the lipid kinase PIKfyve. Chemical inhibition of PIKfyve reduces the targeting of Dram1 to acidic endolysosomal vesicles, arresting Dram1 in multivesicular bodies, early endosomes, or non-acidified vesicles halted in their fusion with early endosomes. In conclusion, Dram1-mediated vesicle fusion requires the formation of PI(3,5)P2 to deliver vesicles and their cargo to the degradative environment of the lysosome.

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