scholarly journals Arf-1 (ADP-ribosylation factor-1) is involved in the activation of a mammalian Na+-selective current

2004 ◽  
Vol 377 (2) ◽  
pp. 539-544 ◽  
Author(s):  
Sebastian STRAUBE ◽  
Anant B. PAREKH
Keyword(s):  
Mammalian Cells ◽  
Kinase Inhibitors ◽  
Brefeldin A ◽  
Cell Types ◽  
Protein Kinase Inhibitors ◽  
Na Current ◽  
Camp Phosphodiesterase ◽  
Pipette Solution ◽  
Adp Ribosylation ◽  
Adp Ribosylation Factor

Stimulation of mammalian cells often results in an increase in the intracellular Na+ concentration, brought about by Na+ influx into the cell via Na+-permeable ion channels. In some cell types, particularly renal epithelia and mast cells, non-hydrolysable analogues of GTP, such as GTP[S] (guanosine 5´-[γ-thio]triphosphate), activate a non-voltage-activated Na+-selective current. We have carried out whole-cell patch–clamp experiments to examine how GTP[S] activates the Na+ current in a rat mast cell line. The ability of GTP[S] to activate Na+ influx was prevented by including GTP in the pipette solution, indicating the involvement of small G-proteins. Brefeldin A and Arf-1-(2–17), inhibitors of Arf-1 (ADP-ribosylation factor-1) proteins, suppressed the activation of Na+ entry by GTP[S]. However, non-active succinylated Arf-1-(2–17) or an N-terminal myristoylated peptide directed towards Arf-5 were ineffective. Arf proteins modulate the cytoskeleton, and disruption of the cytoskeleton with cytochalasin D or its stabilization with phalloidin impaired the development of the Na+ current. Disaggregation of microtubules was without effect. Dialysis with cAMP or inhibition of cAMP phosphodiesterase with caffeine both decreased the extent of Na+ entry, and this was not prevented by pre-treatment with broad-spectrum protein kinase inhibitors. Collectively, our results suggest that the mechanism of activation of a mammalian non-voltage-activated Na+-selective current requires an Arf small G-protein, most probably Arf-1.

scholarly journals ADP-Ribosylation Factor (ARF) Interaction Is Not Sufficient for Yeast GGA Protein Function or Localization

2002 ◽  
Vol 13 (9) ◽  
pp. 3078-3095 ◽  
Author(s):  
Annette L. Boman ◽  
Paul D. Salo ◽  
Melissa J. Hauglund ◽  
Nicole L. Strand ◽  
Shelly J. Rensink ◽  
...  
Keyword(s):  
Membrane Trafficking ◽  
Mammalian Cells ◽  
Fluorescent Protein ◽  
Protein Localization ◽  
Carboxypeptidase Y ◽  
Minor Role ◽  
Temperature Sensitive ◽  
Adp Ribosylation ◽  
And Function ◽  
Adp Ribosylation Factor

Golgi-localized γ-ear homology domain, ADP-ribosylation factor (ARF)-binding proteins (GGAs) facilitate distinct steps of post-Golgi traffic. Human and yeast GGA proteins are only ∼25% identical, but all GGA proteins have four similar domains based on function and sequence homology. GGA proteins are most conserved in the region that interacts with ARF proteins. To analyze the role of ARF in GGA protein localization and function, we performed mutational analyses of both human and yeast GGAs. To our surprise, yeast and human GGAs differ in their requirement for ARF interaction. We describe a point mutation in both yeast and mammalian GGA proteins that eliminates binding to ARFs. In mammalian cells, this mutation disrupts the localization of human GGA proteins. Yeast Gga function was studied using an assay for carboxypeptidase Y missorting and synthetic temperature-sensitive lethality between GGAs andVPS27. Based on these assays, we conclude that non-Arf-binding yeast Gga mutants can function normally in membrane trafficking. Using green fluorescent protein-tagged Gga1p, we show that Arf interaction is not required for Gga localization to the Golgi. Truncation analysis of Gga1p and Gga2p suggests that the N-terminal VHS domain and C-terminal hinge and ear domains play significant roles in yeast Gga protein localization and function. Together, our data suggest that yeast Gga proteins function to assemble a protein complex at the late Golgi to initiate proper sorting and transport of specific cargo. Whereas mammalian GGAs must interact with ARF to localize to and function at the Golgi, interaction between yeast Ggas and Arf plays a minor role in Gga localization and function.

Growth Factors Mobilize Multiple Pools of KCa Channels in Developing Parasympathetic Neurons: Role of ADP-Ribosylation Factors and Related Proteins

2005 ◽  
Vol 94 (2) ◽  
pp. 1597-1605 ◽  
Author(s):  
Kwon-Seok Chae ◽  
Kwang-Seok Oh ◽  
Stuart E. Dryer
Keyword(s):  
Plasma Membrane ◽  
Growth Factors ◽  
Golgi Apparatus ◽  
Bound States ◽  
Brefeldin A ◽  
Dominant Negative ◽  
Over Expression ◽  
Adp Ribosylation ◽  
Phospholipase D1 ◽  
Adp Ribosylation Factor

In developing ciliary ganglion (CG) neurons, movement of functional large-conductance (BK type) Ca2+-activated K+ ( KCa) channels to the cell surface is stimulated by the endogenous growth factors TGFβ1 and β-neuregulin-1 (NRG1). Here we show that a brief NRG1 treatment (0.5–1.5 h) mobilizes KCa channels in a post-Golgi compartment, but longer treatments (>3.5 h) mobilize KCa channels located in the endoplasmic reticulum or Golgi apparatus. Specifically, the effects of 3.5 h NRG1 treatment were completely blocked by treatments that disrupt Golgi apparatus function. These include inhibition of microtubules, or inhibition of the ADP-ribosylation factor-1 (ARF1) system by brefeldin A, by over-expression of dominant-negative ARF1, or over-expression of an ARF1 GTPase-activating protein that blocks ARF1 cycling between GTP- and GDP-bound states. These treatments had no effect on stimulation of KCa evoked by 1.5 h treatment with NRG1, indicating that short-term responses to NRG1 do not require an intact Golgi apparatus. By contrast, both the acute and sustained effects of NRG1 were inhibited by treatments that block trafficking processes that occur close to the plasma membrane. Thus mobilization of KCa was blocked by treatments than inhibit ADP-ribosylation factor-6 (ARF6) signaling, including overexpression of dominant-negative ARF6, dominant-negative ARNO, or dominant-negative phospholipase D1. TGFβ1, the effects of which on KCa are much slower in onset, is unable to selectively mobilize channels in the post-Golgi pool, and its effects on KCa are completely blocked by inhibition of microtubules, Golgi function and also by plasma membrane ARF6 and phospholipase D1 signaling.

scholarly journals ADP Ribosylation Factor 1 Is Required for Synaptic Vesicle Budding in PC12 Cells

1997 ◽  
Vol 138 (3) ◽  
pp. 505-515 ◽  
Author(s):  
Victor Faúndez ◽  
Jim-Tong Horng ◽  
Regis B. Kelly
Keyword(s):  
Pc12 Cell ◽  
Cell Membranes ◽  
Brefeldin A ◽  
T Antigen ◽  
Gtpase Activity ◽  
Vesicle Budding ◽  
Adp Ribosylation ◽  
Adp Ribosylation Factor

Carrier vesicle generation from donor membranes typically progresses through a GTP-dependent recruitment of coats to membranes. Here we explore the role of ADP ribosylation factor (ARF) 1, one of the GTP-binding proteins that recruit coats, in the production of neuroendocrine synaptic vesicles (SVs) from PC12 cell membranes. Brefeldin A (BFA) strongly and reversibly inhibited SV formation in vivo in three different PC12 cell lines expressing vesicle-associated membrane protein–T Antigen derivatives. Other membrane traffic events remained unaffected by the drug, and the BFA effects were not mimicked by drugs known to interfere with formation of other classes of vesicles. The involvement of ARF proteins in the budding of SVs was addressed in a cell-free reconstitution system (Desnos, C., L. Clift-O'Grady, and R.B. Kelly. 1995. J. Cell Biol. 130:1041–1049). A peptide spanning the effector domain of human ARF1 (2–17) and recombinant ARF1 mutated in its GTPase activity, both inhibited the formation of SVs of the correct size. During in vitro incubation in the presence of the mutant ARFs, the labeled precursor membranes acquired different densities, suggesting that the two ARF mutations block at different biosynthetic steps. Cell-free SV formation in the presence of a high molecular weight, ARF-depleted fraction from brain cytosol was significantly enhanced by the addition of recombinant myristoylated native ARF1. Thus, the generation of SVs from PC12 cell membranes requires ARF and uses its GTPase activity, probably to regulate coating phenomena.

scholarly journals Rapid Modulation of Aromatase Activity in the Vertebrate Brain

2013 ◽  
Vol 7 ◽  
pp. JEN.S11268 ◽  
Author(s):  
Thierry D. Charlier ◽  
Charlotte A. Cornil ◽  
Jacques Balthazart
Keyword(s):  
Amino Acids ◽  
Enzymatic Activity ◽  
Kinase Inhibitors ◽  
Cell Types ◽  
Protein Kinase Inhibitors ◽  
Site Directed Mutagenesis ◽  
General Mechanism ◽  
Aromatase Activity ◽  
Vertebrate Brain ◽  
Rapid Modulation

Numerous steroid hormones, including 17β-estradiol (E2), activate rapid and transient cellular, physiological, and behavioral changes in addition to their well-described genomic effects. Aromatase is the key-limiting enzyme in the production of estrogens, and the rapid modulation of this enzymatic activity could produce rapid changes in local E2 concentrations. The mechanisms that might mediate such rapid enzymatic changes are not fully understood but are currently under intense scrutiny. Recent studies in our laboratory indicate that brain aromatase activity is rapidly inhibited by an increase in intracellular calcium concentration resulting from potassium-induced depolarization or from the activation of glutamatergic receptors. Phosphorylating conditions also reduce aromatase activity within minutes, and this inhibition is blocked by the addition of multiple protein kinase inhibitors. This rapid modulation of aromatase activity by phosphorylating conditions is a general mechanism observed in different cell types and tissues derived from a variety of species, including human aromatase expressed in various cell lines. Phosphorylation processes affect aromatase itself and do not involve changes in aromatase protein concentration. The control of aromatase activity by multiple kinases suggests that several amino acids must be concomitantly phosphorylated to modify enzymatic activity but site-directed mutagenesis of several amino acids alone or in combination has not to date revealed the identity of the targeted residue(s). Altogether, the phosphorylation processes affecting aromatase activity provide a new general mechanism by which the concentration of estrogens can be rapidly altered in the brain.

Recruitment of coat-protein-complex proteins on to phagosomal membranes is regulated by a brefeldin A-sensitive ADP-ribosylation factor

2001 ◽  
Vol 355 (2) ◽  
pp. 409-415 ◽  
Author(s):  
Walter BERÓN ◽  
Luis S. MAYORGA ◽  
Maria I. COLOMBO ◽  
Philip D. STAHL
Keyword(s):  
Coat Protein ◽  
Protein Complex ◽  
Brefeldin A ◽  
Type I ◽  
Protein Activity ◽  
Gtp Hydrolysis ◽  
Adp Ribosylation ◽  
Adp Ribosylation Factor ◽  
Particle Internalization ◽  
Coat Protein Complex

Particle internalization in macrophages is followed by a complex maturation process. We have previously observed that proteins bound to phagocytosed particles are sorted from phagosomes into a heterogeneous population of vesicles that fuse with endosomes. However, the mechanism and the protein machinery involved in the formation of these phagosome-derived vesicles are largely unknown. It has been shown that vesicles coated with coat protein complex type I (COPI) have a role in both secretion and endocytosis. To address the possibility that COPI proteins might participate in the formation of phagosome-derived vesicles we studied the recruitment of β-COP to highly purified phagosomes. The binding of β-COP to phagosomal membranes was regulated by nucleotides and inhibited by brefeldin A (BFA). An ADP-ribosylation factor 1 (ARF1) mutant defective in GTP hydrolysis supported the binding of β-COP to phagosomes independently of added nucleotide. AlF4 and Gβγ subunits, agents known to modulate heterotrimeric G-protein activity, were tested in the β-COP binding assay. AlF4 increased β-COP association, whereas binding was inhibited by the addition of Gβγ subunits. Our results suggest that COP proteins are recruited to phagosomal membranes by a mechanism that involves heterotrimeric GTP-binding proteins and a BFA-sensitive ARF. In addition, our findings indicate that COPI proteins are involved in the recycling of components from phagosomes to the cell surface.

scholarly journals ADP-ribosylation factor and coatomer couple fusion to vesicle budding

1994 ◽  
Vol 124 (4) ◽  
pp. 415-424 ◽  
Author(s):  
Z Elazar ◽  
L Orci ◽  
J Ostermann ◽  
M Amherdt ◽  
G Tanigawa ◽  
...  
Keyword(s):  
Brefeldin A ◽  
Retrograde Transport ◽  
Coated Vesicles ◽  
Coat Proteins ◽  
Vesicle Budding ◽  
Adp Ribosylation ◽  
Golgi Membranes ◽  
Transport Vesicles ◽  
Donor And Acceptor ◽  
Adp Ribosylation Factor

The coat proteins required for budding COP-coated vesicles from Golgi membranes, coatomer and ADP-ribosylation factor (ARF) protein, are shown to be required to reconstitute the orderly process of transport between Golgi cisternae in which fusion of transport vesicles begins only after budding ends. When either coat protein is omitted, fusion is uncoupled from budding-donor and acceptor compartments pair directly without an intervening vesicle. Coupling may therefore results from the sequestration of fusogenic membrane proteins into assembling coated vesicles that are only exposed when the coat is removed after budding is complete. This mechanism of coupling explains the phenomenon of "retrograde transport" triggered by uncouplers such as the drug brefeldin A.

scholarly journals ADP-Ribosylation Factor 1 (ARF1) Regulates Recruitment of the AP-3 Adaptor Complex to Membranes

1998 ◽  
Vol 142 (2) ◽  
pp. 391-402 ◽  
Author(s):  
Chean Eng Ooi ◽  
Esteban C. Dell'Angelica ◽  
Juan S. Bonifacino
Keyword(s):  
Membrane Trafficking ◽  
Brefeldin A ◽  
Membrane Association ◽  
Coat Proteins ◽  
Nucleotide Exchange ◽  
Membrane Recruitment ◽  
Adp Ribosylation ◽  
Adp Ribosylation Factor

Small GTP-binding proteins such as ADP- ribosylation factor 1 (ARF1) and Sar1p regulate the membrane association of coat proteins involved in intracellular membrane trafficking. ARF1 controls the clathrin coat adaptor AP-1 and the nonclathrin coat COPI, whereas Sar1p controls the nonclathrin coat COPII. In this study, we demonstrate that membrane association of the recently described AP-3 adaptor is regulated by ARF1. Association of AP-3 with membranes in vitro was enhanced by GTPγS and inhibited by brefeldin A (BFA), an inhibitor of ARF1 guanine nucleotide exchange. In addition, recombinant myristoylated ARF1 promoted association of AP-3 with membranes. The role of ARF1 in vivo was examined by assessing AP-3 subcellular localization when the intracellular level of ARF1-GTP was altered through overexpression of dominant ARF1 mutants or ARF1- GTPase-activating protein (GAP). Lowering ARF1-GTP levels resulted in redistribution of AP-3 from punctate membrane-bound structures to the cytosol as seen by immunofluorescence microscopy. In contrast, increasing ARF1-GTP levels prevented redistribution of AP-3 to the cytosol induced by BFA or energy depletion. Similar experiments with mutants of ARF5 and ARF6 showed that these other ARF family members had little or no effect on AP-3. Taken together, our results indicate that membrane recruitment of AP-3 is promoted by ARF1-GTP. This finding suggests that ARF1 is not a regulator of specific coat proteins, but rather is a ubiquitous molecular switch that acts as a transducer of diverse signals influencing coat assembly.

scholarly journals Characterization of Class I and II ADP-Ribosylation Factors (Arfs) in Live Cells: GDP-bound Class II Arfs Associate with the ER-Golgi Intermediate Compartment Independently of GBF1

2008 ◽  
Vol 19 (8) ◽  
pp. 3488-3500 ◽  
Author(s):  
Justin Chun ◽  
Zoya Shapovalova ◽  
Selma Y. Dejgaard ◽  
John F. Presley ◽  
Paul Melançon
Keyword(s):  
Golgi Complex ◽  
Binding Sites ◽  
Secretory Pathway ◽  
Brefeldin A ◽  
Live Cells ◽  
Adp Ribosylation ◽  
Rapid Release ◽  
Intermediate Compartment ◽  
Adp Ribosylation Factor

Despite extensive work on ADP-ribosylation factor (Arf) 1 at the Golgi complex, the functions of Arf2–5 in the secretory pathway, or for that of any Arf at the ER-Golgi intermediate compartment (ERGIC) remain uncharacterized. Here, we examined the recruitment of fluorescently tagged Arf1, -3, -4, and -5 onto peripheral ERGIC. Live cell imaging detected Arfs on peripheral puncta that also contained Golgi-specific brefeldin A (BFA) resistance factor (GBF) 1 and the ERGIC marker p58. Unexpectedly, BFA did not promote corecruitment of Arfs with GBF1 either at the Golgi complex or the ERGIC, but it uncovered striking differences between Arf1,3 and Arf4,5. Although Arf1,3 quickly dissociated from all endomembranes after BFA addition, Arf4,5 persisted on ERGIC structures, even after redistribution of GBF1 to separate compartments. The GDP-arrested Arf4(T31N) mutant localized to the ERGIC, even with BFA and Exo1 present. In addtion, loss of Arf · GTP after treatment with Exo1 caused rapid release of all Arfs from the Golgi complex and led to GBF1 accumulation on both Golgi and ERGIC membranes. Our results demonstrate that GDP-bound Arf4,5 associate with ERGIC membranes through binding sites distinct from those responsible for GBF1 recruitment. Furthermore, they provide the first evidence that GBF1 accumulation on membranes may be caused by loss of Arf · GTP, rather than the formation of an Arf · GDP · BFA · GBF1 complex.

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