Rab5 activation on macropinosomes requires <scp>ALS</scp>2, and subsequent Rab5 inactivation through <scp>ALS</scp>2 detachment requires active Rab7

Morishita, So; Wada, Naoki; Fukuda, Mitsunori; Nakamura, Takeshi

doi:10.1002/1873-3468.13306

Cited by 12 publications

(7 citation statements)

References 40 publications

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“…Conversely, a few studies have investigated the role of ALS2 in non-neuronal cell types, and most importantly, our understanding the effects of ALS2 in cellular aspects that are beyond those reported in neuronal function, remain limiting. Specifically, using COS-7 and HeLa cells, ALS2 was shown to promote Rab5 activation at macropinosomes 38 , whereas mutant ALS2 failed to localize to macropinosomes and was associated with defective autophagy/endolysosomal dynamics in HeLa cells 39 and in ALS2-deficient primary cultured neurons 40 . Likewise, in fibroblasts, ALS2 was reported to co-localize with Rac1 at membrane ruffles and peripheral lamellipodia, suggesting a role in endocytic trafficking and cytoskeleton remodeling 22 .…”

Section: Discussionmentioning

confidence: 99%

The RabGEF ALS2 is a hypoxia inducible target associated with the acquisition of aggressive traits in tumor cells

Rivas

Silva

Reyes

et al. 2020

Sci Rep

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Tumor hypoxia and the hypoxia inducible factor-1, HIF-1, play critical roles in cancer progression and metastasis. We previously showed that hypoxia activates the endosomal GTPase Rab5, leading to tumor cell migration and invasion, and that these events do not involve changes in Rab protein expression, suggesting the participation of intermediate activators. Here, we identified ALS2, a guanine nucleotide exchange factor that is upregulated in cancer, as responsible for increased Rab5-GTP loading, cell migration and metastasis in hypoxia. Specifically, hypoxia augmented ALS2 mRNA and protein levels, and these events involved HIF-1α-dependent transcription, as shown by RNAi, pharmacological inhibition, chromatin immunoprecipitation and bioinformatics analyses, which identified a functional HIF-1α-binding site in the proximal promoter region of ALS2. Moreover, ALS2 and Rab5 activity were elevated both in a model of endogenous HIF-1α stabilization (renal cell carcinoma) and by following expression of stable non-hydroxylatable HIF-1α. Strikingly, ALS2 upregulation in hypoxia was required for Rab5 activation, tumor cell migration and invasion, as well as experimental metastasis in C57BL/6 mice. Finally, immunohistochemical analyses in patient biopsies with renal cell carcinoma showed that elevated HIF-1α correlates with increased ALS2 expression. Hence, this study identifies ALS2 as a novel hypoxia-inducible gene associated with tumor progression and metastasis.

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Section: Discussionmentioning

confidence: 99%

The RabGEF ALS2 is a hypoxia inducible target associated with the acquisition of aggressive traits in tumor cells

Rivas

Silva

Reyes

et al. 2020

Sci Rep

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“…Early macropinosomes harbor Rab5 ( Feliciano et al, 2011 ; Maxson et al, 2021 ), which in turn recruits the class III PI3K Vps34, which catalyzes the reaction from PI to PI(3)P ( Christoforidis et al, 1999 ; Kerr and Teasdale, 2009 ). In macropinosomes routed toward lysosomes, Rab5 is replaced by Rab7 ( Racoosin and Swanson, 1993 ; Kerr et al, 2006 ; Langemeyer et al, 2018 ; Morishita et al, 2019 ). In an analogy to an electrical safety-breaker, Del Conte-Zerial et al (2008) compare the replacement of Rab5 by Rab7 as a “cut-out switch.” This model predicts that Rab5 drives Rab7 activation above a distinct threshold.…”

Section: Macropinocytosismentioning

confidence: 99%

“…Thus, the Rab5 to Rab7 switch ensures a unidirectional route of cargo-loaded macropinosomes toward lysosomes. Using Förster/fluorescence resonance energy transfer (FRET) imaging, Morishita et al (2019) describe that active Rab5 facilitates Rab7 activation until Rab7 sustains its own activity and inactivates Rab5. Furthermore, recruitment of amyotrophic lateral sclerosis 2 (ALS2) to the macropinosome coincides with Rab5 activation, and ALS2 detachment is associated with Rab5 inactivation ( Morishita et al, 2019 ).…”

Section: Macropinocytosismentioning

confidence: 99%

“…Using Förster/fluorescence resonance energy transfer (FRET) imaging, Morishita et al (2019) describe that active Rab5 facilitates Rab7 activation until Rab7 sustains its own activity and inactivates Rab5. Furthermore, recruitment of amyotrophic lateral sclerosis 2 (ALS2) to the macropinosome coincides with Rab5 activation, and ALS2 detachment is associated with Rab5 inactivation ( Morishita et al, 2019 ). In earlier studies using Texas red-labeled dextran macropinosomes, Racoosin and Swanson showed that Rab7-positive macropinosomes fuse with tubular lysosomes ( Racoosin and Swanson, 1993 ).…”

Section: Macropinocytosismentioning

confidence: 99%

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From Pinocytosis to Methuosis—Fluid Consumption as a Risk Factor for Cell Death

Ritter

Bresgen

Kerschbaum

2021

Front. Cell Dev. Biol.

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The volumes of a cell [cell volume (CV)] and its organelles are adjusted by osmoregulatory processes. During pinocytosis, extracellular fluid volume equivalent to its CV is incorporated within an hour and membrane area equivalent to the cell’s surface within 30 min. Since neither fluid uptake nor membrane consumption leads to swelling or shrinkage, cells must be equipped with potent volume regulatory mechanisms. Normally, cells respond to outwardly or inwardly directed osmotic gradients by a volume decrease and increase, respectively, i.e., they shrink or swell but then try to recover their CV. However, when a cell death (CD) pathway is triggered, CV persistently decreases in isotonic conditions in apoptosis and it increases in necrosis. One type of CD associated with cell swelling is due to a dysfunctional pinocytosis. Methuosis, a non-apoptotic CD phenotype, occurs when cells accumulate too much fluid by macropinocytosis. In contrast to functional pinocytosis, in methuosis, macropinosomes neither recycle nor fuse with lysosomes but with each other to form giant vacuoles, which finally cause rupture of the plasma membrane (PM). Understanding methuosis longs for the understanding of the ionic mechanisms of cell volume regulation (CVR) and vesicular volume regulation (VVR). In nascent macropinosomes, ion channels and transporters are derived from the PM. Along trafficking from the PM to the perinuclear area, the equipment of channels and transporters of the vesicle membrane changes by retrieval, addition, and recycling from and back to the PM, causing profound changes in vesicular ion concentrations, acidification, and—most importantly—shrinkage of the macropinosome, which is indispensable for its proper targeting and cargo processing. In this review, we discuss ion and water transport mechanisms with respect to CVR and VVR and with special emphasis on pinocytosis and methuosis. We describe various aspects of the complex mutual interplay between extracellular and intracellular ions and ion gradients, the PM and vesicular membrane, phosphoinositides, monomeric G proteins and their targets, as well as the submembranous cytoskeleton. Our aim is to highlight important cellular mechanisms, components, and processes that may lead to methuotic CD upon their derangement.

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“…For candidate-based approaches, specific proteins known to be present on macropinosomes are labelled, for example, by genetically encoded fluorescent probes to monitor them by standard fluorescence microscopy (Buckley et al, 2016;Morishita et al, 2019).…”

Section: Candidate-based Approaches To Trace Macropinosomesmentioning

confidence: 99%

New methods to decrypt emerging macropinosome functions during the host–pathogen crosstalk

Chang

Enninga

Stévenin

2021

Cellular Microbiology

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Large volumes of liquid and other materials from the extracellular environment are internalised by eukaryotic cells via an endocytic process called macropinocytosis. It is now recognised that this fundamental and evolutionarily conserved pathway is hijacked by numerous intracellular pathogens as an entry portal to the host cell interior. Yet, an increasing number of additional cellular functions of macropinosomes in pathologic processes have been reported beyond this role for fluid internalisation. It emerges that the identity of macropinosomes can vary hugely and change rapidly during their lifetime. A deeper understanding of this important multi-faceted compartment is based on novel methods for their investigation. These methods are either imaging-based for the tracking of macropinosome dynamics, or they provide the means to extract macropinosomes at high purity for comprehensive proteomic analyses. Here, we portray these new approaches for the investigation of macropinosomes. We document how these method developments have provided insights for a new understanding of the intracellular lifestyle of the bacterial pathogens Shigella and Salmonella. We suggest that a systematic complete characterisation of macropinosome subversion with these approaches during other infection processes and pathologies will be highly beneficial for our understanding of the underlying cellular and molecular processes.

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Rab5 activation on macropinosomes requires ALS2, and subsequent Rab5 inactivation through ALS2 detachment requires active Rab7

Cited by 12 publications

References 40 publications

The RabGEF ALS2 is a hypoxia inducible target associated with the acquisition of aggressive traits in tumor cells

The RabGEF ALS2 is a hypoxia inducible target associated with the acquisition of aggressive traits in tumor cells

From Pinocytosis to Methuosis—Fluid Consumption as a Risk Factor for Cell Death

New methods to decrypt emerging macropinosome functions during the host–pathogen crosstalk

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