scholarly journals RUFY3 and RUFY4 are ARL8 effectors that couple lysosomes to dynein-dynactin

2021 ◽  
Author(s):  
Tal Keren-Kaplan ◽  
Amra Saric ◽  
Saikat Ghosh ◽  
Chad Williamson ◽  
Rui Jia ◽  
...  
Keyword(s):  
Hippocampal Neurons ◽  
Retrograde Transport ◽  
Small Gtpase ◽  
Serum Starvation ◽  
Anterograde Transport ◽  
Fyve Domain ◽  
Axon Development ◽  
Necessary And Sufficient

Abstract The small GTPase ARL8 associates with lysosomes and recruits several effectors that mediate coupling to kinesins for anterograde transport, as well as tethering for eventual fusion with other organelles. Herein we report the identification of the “RUN- and FYVE-domain-containing” proteins RUFY3 and RUFY4 as novel ARL8 effectors that couple lysosomes to dynein-dynactin for retrograde transport. Using various biochemical approaches, we find that RUFY3/4 interact with both GTP-bound ARL8 and dynein-dynactin. In addition, we show that RUFY3/4 are both necessary and sufficient for concentration of lysosomes in the juxtanuclear area of the cell. RUFY3/4 also promote retrograde transport of lysosomes in the axon of hippocampal neurons. The function of RUFY3/4 in retrograde transport is required for juxtanuclear redistribution of lysosomes upon serum starvation or cytoplasmic alkalinization, and may underlie the reported roles of RUFY3/4 in axon development/degeneration, cancer and immunity. These studies thus establish RUFY3/4 as novel ARL8-dependent, dynein-dynactin adaptors, and highlight the role of ARL8 in the regulation of both anterograde and retrograde lysosome transport.  

scholarly journals The GTPase IFT27 is involved in both anterograde and retrograde intraflagellar transport

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Diego Huet ◽  
Thierry Blisnick ◽  
Sylvie Perrot ◽  
Philippe Bastin
Keyword(s):  
Trypanosoma Brucei ◽  
Protein Complexes ◽  
Intraflagellar Transport ◽  
Retrograde Transport ◽  
Small Gtpase ◽  
Anterograde Transport ◽  
Cargo Transport ◽  
Cilia And Flagella ◽  
Bidirectional Movement

The construction of cilia and flagella depends on intraflagellar transport (IFT), the bidirectional movement of two protein complexes (IFT-A and IFT-B) driven by specific kinesin and dynein motors. IFT-B and kinesin are associated to anterograde transport whereas IFT-A and dynein participate to retrograde transport. Surprisingly, the small GTPase IFT27, a member of the IFT-B complex, turns out to be essential for retrograde cargo transport in Trypanosoma brucei. We reveal that this is due to failure to import both the IFT-A complex and the IFT dynein into the flagellar compartment. To get further molecular insight about the role of IFT27, GDP- or GTP-locked versions were expressed in presence or absence of endogenous IFT27. The GDP-locked version is unable to enter the flagellum and to interact with other IFT-B proteins and its sole expression prevents flagellum formation. These findings demonstrate that a GTPase-competent IFT27 is required for association to the IFT complex and that IFT27 plays a role in the cargo loading of the retrograde transport machinery.

scholarly journals Retrograde Transport from the Pre-Golgi Intermediate Compartment and the Golgi Complex Is Affected by the Vacuolar H+-ATPase Inhibitor Bafilomycin A1

1998 ◽  
Vol 9 (12) ◽  
pp. 3561-3578 ◽  
Author(s):  
Harri Palokangas ◽  
Ming Ying ◽  
Kalervo Väänänen ◽  
Jaakko Saraste
Keyword(s):  
Brefeldin A ◽  
Retrograde Transport ◽  
Small Gtpase ◽  
Bafilomycin A1 ◽  
Atpase Inhibitor ◽  
Marker Proteins ◽  
Golgi Region ◽  
Intermediate Compartment ◽  
Acidic Compartments

The effect of the vacuolar H+-ATPase inhibitor bafilomycin A1 (Baf A1) on the localization of pre-Golgi intermediate compartment (IC) and Golgi marker proteins was used to study the role of acidification in the function of early secretory compartments. Baf A1 inhibited both brefeldin A- and nocodazole-induced retrograde transport of Golgi proteins to the endoplasmic reticulum (ER), whereas anterograde ER-to-Golgi transport remained largely unaffected. Furthermore, p58/ERGIC-53, which normally cycles between the ER, IC, and cis-Golgi, was arrested in pre-Golgi tubules and vacuoles, and the number of p58-positive ∼80-nm Golgi (coatomer protein I) vesicles was reduced, suggesting that the drug inhibits the retrieval of the protein from post-ER compartments. In parallel, redistribution of β-coatomer protein from the Golgi to peripheral pre-Golgi structures took place. The small GTPase rab1p was detected in short pre-Golgi tubules in control cells and was efficiently recruited to the tubules accumulating in the presence of Baf A1. In contrast, these tubules showed no enrichment of newly synthesized, anterogradely transported proteins, indicating that they participate in retrograde transport. These results suggest that the pre-Golgi structures contain an active H+-ATPase that regulates retrograde transport at the ER–Golgi boundary. Interestingly, although Baf A1 had distinct effects on peripheral pre-Golgi structures, only more central, p58-containing elements accumulated detectable amounts of 3-(2,4-dinitroanilino)-3′-amino-N-methyldipropylamine (DAMP), a marker for acidic compartments, raising the possibility that the lumenal pH of the pre-Golgi structures gradually changes in parallel with their translocation to the Golgi region.

scholarly journals Effects of the dynein inhibitor dynarrestin on the number of motor proteins transporting synaptic cargos

2020 ◽  
Author(s):  
Kumiko Hayashi ◽  
Miki G. Miyamoto ◽  
Shinsuke Niwa
Keyword(s):  
Axonal Transport ◽  
Optical Tweezers ◽  
Hippocampal Neurons ◽  
Motor Proteins ◽  
Force Measurement ◽  
Retrograde Transport ◽  
Long Distance ◽  
Anterograde Transport ◽  
Non Invasive ◽  
Physical Measurements

AbstractSynaptic cargo transport by kinesin and dynein in hippocampal neurons was investigated using non-invasive measurements of transport force based on non-equilibrium statistical mechanics. Although direct physical measurements such as force measurement using optical tweezers are difficult in an intracellular environment, the non-invasive estimations enabled enumerating force producing units (FPUs) carrying a cargo comprising the motor proteins generating force. The number of FPUs served as a barometer for stable and long-distance transport by multiple motors, which was then used to quantify the extent of damage to axonal transport by dynarrestin, a dynein inhibitor. We found that dynarrestin decreased the FPU for retrograde transport more than anterograde transport. In the future, these measurements may be used to quantify the damage to axonal transport resulting from neuronal diseases including Alzheimer’s, Parkinson’s, and Huntington’s diseases.

scholarly journals Rab7a and Mitophagosome Formation

Cells ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 224 ◽  
Author(s):  
Esther Tan ◽  
Bor Tang
Keyword(s):  
Retrograde Transport ◽  
Small Gtpase ◽  
Guanine Nucleotide ◽  
Nucleotide Exchange ◽  
Autophagosome Formation ◽  
Guanine Nucleotide Exchange ◽  
Gtpase Activating Proteins ◽  
Retromer Complex ◽  
Nucleotide Exchange Factor

The small GTPase, Rab7a, and the regulators of its GDP/GTP-binding status were shown to have roles in both endocytic membrane traffic and autophagy. Classically known to regulate endosomal retrograde transport and late endosome-lysosome fusion, earlier work has indicated a role for Rab7a in autophagosome-lysosome fusion as well as autolysosome maturation. However, as suggested by recent findings on PTEN-induced kinase 1 (PINK1)-Parkin-mediated mitophagy, Rab7a and its regulators are critical for the correct targeting of Atg9a-bearing vesicles to effect autophagosome formation around damaged mitochondria. This mitophagosome formation role for Rab7a is dependent on an intact Rab cycling process mediated by the Rab7a-specific guanine nucleotide exchange factor (GEF) and GTPase activating proteins (GAPs). Rab7a activity in this regard is also dependent on the retromer complex, as well as phosphorylation by the TRAF family-associated NF-κB activator binding kinase 1 (TBK1). Here, we discuss these recent findings and broadened perspectives on the role of the Rab7a network in PINK1-Parkin mediated mitophagy.

scholarly journals A deficiency of the small GTPase rab8 inhibits membrane traffic in developing neurons.

1995 ◽  
Vol 15 (2) ◽  
pp. 918-924 ◽  
Author(s):  
L A Huber ◽  
P Dupree ◽  
C G Dotti
Keyword(s):  
Hippocampal Neurons ◽  
Membrane Traffic ◽  
Small Gtpase ◽  
Fluorescence Labeling ◽  
Differential Interference Contrast Microscopy ◽  
Anterograde Transport ◽  
Fluorescent Marker ◽  
Rab Protein ◽  
Gtp Binding ◽  
Developing Neurons

One of the major activities of developing neurons is the transport of new membrane to the growing axon. Candidates for playing a key role in the regulation of this intense traffic are the small GTP-binding proteins of the rab family. We have used hippocampal neurons in culture and analyzed membrane traffic activity after suppressing the expression of the small GTP-binding protein rab8. Inhibition of protein expression was accomplished by using sequence-specific antisense oligonucleotides. While rab8 depletion resulted in the blockage of morphological maturation in 95% of the neurons, suppression of expression of another rab protein, rab3a, had no effect, and all neurons developed normal axons and dendrites. The impairment of neuronal maturation by rab8 antisense treatment was due to inhibition of membrane traffic. Thus, by using video-enhanced differential interference contrast microscopy, we observed in the rab8-depleted cells a dramatic reduction in the number of vesicles undergoing anterograde transport. Moreover, by incubating antisense-treated neurons with Bodipy-labeled ceramide, a fluorescent marker for newly formed exocytic vesicles, we observed fluorescence labeling restricted to the Golgi apparatus, whereas in control cells labeling was found also in the neurites. These results show the role of the small GTPase rab8 in membrane traffic during neuronal process outgrowth.

scholarly journals Biochemical and structural insights into Rab12 interactions with RILP and its family members

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jana Omar ◽  
Efrat Rosenbaum ◽  
Adi Efergan ◽  
Bayan Abu Sneineh ◽  
Adva Yeheskel ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Mast Cell ◽  
Single Molecule ◽  
Secretory Granules ◽  
Retrograde Transport ◽  
Small Gtpase ◽  
The Other ◽  
Dynamics Simulations ◽  
Structural Insights

AbstractAlongside its biosynthetic functions, the small GTPase Rab12 negatively regulates mast cell (MC) exocytosis by its interaction with RILP to promote retrograde transport of the MC secretory granules. Given the role of Rab effectors in mediating Rab functions, in this study we used biochemical and in silico tools to decipher Rab12 interactions with its RILP family effectors. We show that Rab12 interacts with RILP, RILP-L1 and RILP-L2 independently of each other, whereby lysine-71, in mouse Rab12, is critical for Rab12 interactions with RILP-L1 or RILP-L2, but is dispensable for the binding of RILP. Focusing on RILP, and relying on molecular dynamics simulations, functional mutational analyses and peptide inhibition assays, we propose a model for the Rab12-RILP complex, consisting of a RILP homodimer and a single molecule of active Rab12, that interacts with the RILP homology domain (RHD) of one RILP monomer and a C-terminal threonine in the other monomer via its switch I and switch II regions. Mutational analyses of RILP RHD also demonstrate its involvement in the regulation of MC secretory granule transport. Jointly, our results provide structural and functional insights into the Rab12-RILP complex on the basis of which new tools could be generated for decoding Rab12 functions.

scholarly journals Regulation of Somatodendritic GABAA Receptor Channels in Rat Hippocampal Neurons: Evidence for a Role of the Small GTPase Rac1

2000 ◽  
Vol 20 (18) ◽  
pp. 6743-6751 ◽  
Author(s):  
Dieter K. Meyer ◽  
Claudia Olenik ◽  
Fred Hofmann ◽  
Holger Barth ◽  
Jost Leemhuis ◽  
...  
Keyword(s):  
Gabaa Receptor ◽  
Hippocampal Neurons ◽  
Small Gtpase

A Proposed Framework Emphasizing Auditor Reliability over Auditor Independence

2003 ◽  
Vol 17 (3) ◽  
pp. 257-266 ◽  
Author(s):  
Mark H. Taylor ◽  
F. Todd DeZoort ◽  
Edward Munn ◽  
Martha Wetterhall Thomas
Keyword(s):  
Public Interest ◽  
Auditor Independence ◽  
Public Confidence ◽  
Sufficient Condition ◽  
Necessary And Sufficient Condition ◽  
Accounting Profession ◽  
The Public ◽  
Necessary And Sufficient

This paper introduces an auditor reliability framework that repositions the role of auditor independence in the accounting profession. The framework is motivated in part by widespread confusion about independence and the auditing profession's continuing problems with managing independence and inspiring public confidence. We use philosophical, theoretical, and professional arguments to argue that the public interest will be best served by reprioritizing professional and ethical objectives to establish reliability in fact and appearance as the cornerstone of the profession, rather than relationship-based independence in fact and appearance. This revised framework requires three foundation elements to control subjectivity in auditors' judgments and decisions: independence, integrity, and expertise. Each element is a necessary but not sufficient condition for maximizing objectivity. Objectivity, in turn, is a necessary and sufficient condition for achieving and maintaining reliability in fact and appearance.

scholarly journals Cdk5 and GSK3β inhibit fast endophilin-mediated endocytosis

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Antonio P. A. Ferreira ◽  
Alessandra Casamento ◽  
Sara Carrillo Roas ◽  
Els F. Halff ◽  
James Panambalana ◽  
...  
Keyword(s):  
Hippocampal Neurons ◽  
Growth Factor Receptor ◽  
Receptor Activation ◽  
Surface Proteins ◽  
Serum Starvation ◽  
Negative Regulators ◽  
Cell Surface Proteins ◽  
Local Regulation ◽  
Axon Elongation ◽  
Cone Formation

AbstractEndocytosis mediates the cellular uptake of micronutrients and cell surface proteins. Fast Endophilin-mediated endocytosis, FEME, is not constitutively active but triggered upon receptor activation. High levels of growth factors induce spontaneous FEME, which can be suppressed upon serum starvation. This suggested a role for protein kinases in this growth factor receptor-mediated regulation. Using chemical and genetic inhibition, we find that Cdk5 and GSK3β are negative regulators of FEME. They antagonize the binding of Endophilin to Dynamin-1 and to CRMP4, a Plexin A1 adaptor. This control is required for proper axon elongation, branching and growth cone formation in hippocampal neurons. The kinases also block the recruitment of Dynein onto FEME carriers by Bin1. As GSK3β binds to Endophilin, it imposes a local regulation of FEME. Thus, Cdk5 and GSK3β are key regulators of FEME, licensing cells for rapid uptake by the pathway only when their activity is low.

scholarly journals Phosphorylation of GAPVD1 Is Regulated by the PER Complex and Linked to GAPVD1 Degradation

2021 ◽  
Vol 22 (7) ◽  
pp. 3787
Author(s):  
Hussam Ibrahim ◽  
Philipp Reus ◽  
Anna Katharina Mundorf ◽  
Anna-Lena Grothoff ◽  
Valerie Rudenko ◽  
...  
Keyword(s):  
Circadian Clock ◽  
Transcriptional Repression ◽  
Small Gtpase ◽  
Main Role ◽  
Interacting Proteins ◽  
Casein Kinase 1 ◽  
Bona Fide ◽  
Kinetics Of

Repressor protein period (PER) complexes play a central role in the molecular oscillator mechanism of the mammalian circadian clock. While the main role of nuclear PER complexes is transcriptional repression, much less is known about the functions of cytoplasmic PER complexes. We found with a biochemical screen for PER2-interacting proteins that the small GTPase regulator GTPase-activating protein and VPS9 domain-containing protein 1 (GAPVD1), which has been identified previously as a component of cytoplasmic PER complexes in mice, is also a bona fide component of human PER complexes. We show that in situ GAPVD1 is closely associated with casein kinase 1 delta (CSNK1D), a kinase that regulates PER2 levels through a phosphoswitch mechanism, and that CSNK1D regulates the phosphorylation of GAPVD1. Moreover, phosphorylation determines the kinetics of GAPVD1 degradation and is controlled by PER2 and a C-terminal autoinhibitory domain in CSNK1D, indicating that the regulation of GAPVD1 phosphorylation is a novel function of cytoplasmic PER complexes and might be part of the oscillator mechanism or an output function of the circadian clock.

Sign in / Sign up

Export Citation Format

Share Document