scholarly journals Energy metabolism regulates clathrin adaptors at the trans-Golgi network and endosomes

2013 ◽  
Vol 24 (6) ◽  
pp. 832-847 ◽  
Author(s):  
Quyen L. Aoh ◽  
Chao-wei Hung ◽  
Mara C. Duncan
Keyword(s):  
Energy Metabolism ◽  
Intracellular Signaling ◽  
Phosphatidyl Inositol ◽  
Glucose Starvation ◽  
Yeast Saccharomyces Cerevisiae ◽  
Permeabilized Cells ◽  
Trans Golgi Network ◽  
Golgi Network ◽  
Energy Dependent ◽  
Adp Ribosylation Factor

Glucose is a master regulator of cell behavior in the yeast Saccharomyces cerevisiae. It acts as both a metabolic substrate and a potent regulator of intracellular signaling cascades. Glucose starvation induces the transient delocalization and then partial relocalization of clathrin adaptors at the trans-Golgi network and endosomes. Although these localization responses are known to depend on the protein kinase A (PKA) signaling pathway, the molecular mechanism of this regulation is unknown. Here we demonstrate that PKA and the AMP-regulated kinase regulate adaptor localization through changes in energy metabolism. We show that genetic and chemical manipulation of intracellular ATP levels cause corresponding changes in adaptor localization. In permeabilized cells, exogenous ATP is sufficient to induce adaptor localization. Furthermore, we reveal distinct energy-dependent steps in adaptor localization: a step that requires the ADP-ribosylation factor ARF, an ATP-dependent step that requires the phosphatidyl-inositol-4 kinase Pik1, and third ATP-dependent step for which we provide evidence but for which the mechanism is unknown. We propose that these energy-dependent mechanisms precisely synchronize membrane traffic with overall proliferation rates and contribute a crucial aspect of energy conservation during acute glucose starvation.

scholarly journals Glucose regulates clathrin adaptors at the trans-Golgi network and endosomes

2011 ◽  
Vol 22 (19) ◽  
pp. 3671-3683 ◽  
Author(s):  
Quyen L. Aoh ◽  
Lee M. Graves ◽  
Mara C. Duncan
Keyword(s):  
Cell Polarity ◽  
Translation Initiation ◽  
Posttranslational Modifications ◽  
Raw Material ◽  
Eukaryotic Cells ◽  
Glucose Starvation ◽  
Yeast Saccharomyces Cerevisiae ◽  
Trans Golgi Network ◽  
Golgi Network ◽  
Biomass Increase

Glucose is a rich source of energy and the raw material for biomass increase. Many eukaryotic cells remodel their physiology in the presence and absence of glucose. The yeast Saccharomyces cerevisiae undergoes changes in transcription, translation, metabolism, and cell polarity in response to glucose availability. Upon glucose starvation, translation initiation and cell polarity are immediately inhibited, and then gradually recover. In this paper, we provide evidence that, as in cell polarity and translation, traffic at the trans-Golgi network (TGN) and endosomes is regulated by glucose via an unknown mechanism that depends on protein kinase A (PKA). Upon glucose withdrawal, clathrin adaptors exhibit a biphasic change in localization: they initially delocalize from the membrane within minutes and later partially recover onto membranes. Additionally, the removal of glucose induces changes in posttranslational modifications of adaptors. Ras and Gpr1 signaling pathways, which converge on PKA, are required for changes in adaptor localization and changes in posttranslational modifications. Acute inhibition of PKA demonstrates that inhibition of PKA prior to glucose withdrawal prevents several adaptor responses to starvation. This study demonstrates that PKA activity prior to glucose starvation primes membrane traffic at the TGN and endosomes in response to glucose starvation.

scholarly journals Plasma membrane to vacuole traffic induced by glucose starvation requires Gga2‐dependent sorting at the trans ‐Golgi network

2020 ◽  
Vol 112 (11) ◽  
pp. 349-367
Author(s):  
Destiney Buelto ◽  
Chao‐Wei Hung ◽  
Quyen L. Aoh ◽  
Sagar Lahiri ◽  
Mara C. Duncan
Keyword(s):  
Plasma Membrane ◽  
Glucose Starvation ◽  
Trans Golgi Network ◽  
Golgi Network

scholarly journals Yeast Golgi-localized, γ-Ear–containing, ADP-Ribosylation Factor-binding Proteins Are but Adaptor Protein-1 Is Not Required for Cell-free Transport of Membrane Proteins from the Trans-Golgi Network to the Prevacuolar Compartment

2008 ◽  
Vol 19 (11) ◽  
pp. 4826-4836 ◽  
Author(s):  
Mohamed E. Abazeed ◽  
Robert S. Fuller
Keyword(s):  
Binding Proteins ◽  
Adaptor Protein ◽  
Early Endosome ◽  
Dominant Negative ◽  
Factor Binding ◽  
Trans Golgi Network ◽  
Direct Pathway ◽  
Prevacuolar Compartment ◽  
Golgi Network ◽  
Adp Ribosylation Factor

Golgi-localized, γ-Ear–containing, ADP-ribosylation factor-binding proteins (GGAs) and adaptor protein-1 (AP-1) mediate clathrin-dependent trafficking of transmembrane proteins between the trans-Golgi network (TGN) and endosomes. In yeast, the vacuolar sorting receptor Vps10p follows a direct pathway from the TGN to the late endosome/prevacuolar compartment (PVC), whereas, the processing protease Kex2p partitions between the direct pathway and an indirect pathway through the early endosome. To examine the roles of the Ggas and AP-1 in TGN–PVC transport, we used a cell-free assay that measures delivery to the PVC of either Kex2p or a chimeric protein (K-V), in which the Vps10p cytosolic tail replaces the Kex2p tail. Either antibody inhibition or dominant-negative Gga2p completely blocked K-V transport but only partially blocked Kex2p transport. Deletion of APL2, encoding the β subunit of AP-1, did not affect K-V transport but partially blocked Kex2p transport. Residual Kex2p transport seen with apl2Δ membranes was insensitive to dominant-negative Gga2p, suggesting that the apl2Δ mutation causes Kex2p to localize to a compartment that precludes Gga-dependent trafficking. These results suggest that yeast Ggas facilitate the specific and direct delivery of Vps10p and Kex2p from the TGN to the PVC and that AP-1 modulates Kex2p trafficking through a distinct pathway, presumably involving the early endosome.

scholarly journals ADP ribosylation factor and a 14-kD polypeptide are associated with heparan sulfate-carrying post-trans-Golgi network secretory vesicles in rat hepatocytes.

1994 ◽  
Vol 125 (4) ◽  
pp. 721-732 ◽  
Author(s):  
W Nickel ◽  
L A Huber ◽  
R A Kahn ◽  
N Kipper ◽  
A Barthel ◽  
...  
Keyword(s):  
Heparan Sulfate ◽  
Plasma Membranes ◽  
Vesicular Transport ◽  
Rat Hepatocytes ◽  
Secretory Vesicles ◽  
Isolated Rat Hepatocytes ◽  
Adp Ribosylation ◽  
Trans Golgi Network ◽  
Golgi Network ◽  
Adp Ribosylation Factor

Constitutive secretory vesicles carrying heparan sulfate proteoglycan (HSPG) were identified in isolated rat hepatocytes by pulse-chase experiments with [35S]sulfate and purified by velocity-controlled sucrose gradient centrifugation followed by equilibrium density centrifugation in Nycodenz. Using this procedure, the vesicles were separated from plasma membranes, Golgi, trans-Golgi network (TGN), ER, endosomes, lysosomes, transcytotic vesicles, and mitochondria. The diameter of these vesicles was approximately 100-200 nm as determined by electron microscopy. A typical coat structure as described for intra-Golgi transport vesicles or clathrin-coated vesicles could not be seen, and the vesicles were not associated with the coat protein beta-COP. Furthermore, the vesicles appear to represent a low density compartment (1.05-1.06 g/ml). Other constitutively secreted proteins (rat serum albumin, apolipoprotein E, and fibrinogen) could not be detected in purified HSPG-carrying vesicles, but banded in the denser fractions of the Nycodenz gradient. Moreover, during pulse-chase labeling with [35S]methionine, labeled albumin did not appear in the post-TGN vesicle fraction carrying HSPGs. These findings indicate sorting of HSPGs and albumin into different types of constitutive secretory vesicles in hepatocytes. Two proteins were found to be tightly associated with the membranes of the HSPG carrying vesicles: a member of the ADP ribosylation factor family of small guanine nucleotide-binding proteins and an unknown 14-kD peripheral membrane protein (VAPP14). Concerning the secretory pathway, we conclude from these results that ADP ribosylation factor proteins are not only involved in vesicular transport from the ER via the Golgi to the TGN, but also in vesicular transport from the TGN to the plasma membrane.

scholarly journals Segregation of sphingolipids and sterols during formation of secretory vesicles at the trans-Golgi network

2009 ◽  
Vol 185 (4) ◽  
pp. 601-612 ◽  
Author(s):  
Robin W. Klemm ◽  
Christer S. Ejsing ◽  
Michal A. Surma ◽  
Hermann-Josef Kaiser ◽  
Mathias J. Gerl ◽  
...  
Keyword(s):  
Membrane Trafficking ◽  
Secretory Pathway ◽  
Membrane Lipids ◽  
Secretory Vesicles ◽  
Shotgun Lipidomics ◽  
Yeast Saccharomyces Cerevisiae ◽  
Trans Golgi Network ◽  
Sorting Station ◽  
Golgi Network ◽  
First Time

The trans-Golgi network (TGN) is the major sorting station in the secretory pathway of all eukaryotic cells. How the TGN sorts proteins and lipids to generate the enrichment of sphingolipids and sterols at the plasma membrane is poorly understood. To address this fundamental question in membrane trafficking, we devised an immunoisolation procedure for specific recovery of post-Golgi secretory vesicles transporting a transmembrane raft protein from the TGN to the cell surface in the yeast Saccharomyces cerevisiae. Using a novel quantitative shotgun lipidomics approach, we could demonstrate that TGN sorting selectively enriched ergosterol and sphingolipid species in the immunoisolated secretory vesicles. This finding, for the first time, indicates that the TGN exhibits the capacity to sort membrane lipids. Furthermore, the observation that the immunoisolated vesicles exhibited a higher membrane order than the late Golgi membrane, as measured by C-Laurdan spectrophotometry, strongly suggests that lipid rafts play a role in the TGN-sorting machinery.

scholarly journals The morphology but not the function of endosomes and lysosomes is altered by brefeldin A.

1992 ◽  
Vol 119 (2) ◽  
pp. 273-285 ◽  
Author(s):  
S A Wood ◽  
W J Brown
Keyword(s):  
Brefeldin A ◽  
Cell Types ◽  
Trans Golgi Network ◽  
Testicular Cells ◽  
Early Endosomes ◽  
Golgi Network ◽  
Endocytic Traffic ◽  
Energy Dependent ◽  
Different Cell Types ◽  
Compact Cluster

Brefeldin A (BFA) induces the formation of an extensively fused network of membranes derived from the trans-Golgi network (TGN) and early endosomes (EE). We describe in detail here the unaffected passage of endocytosed material through the fused TGN/EE compartments to lysosomes in BFA-treated cells. We also confirmed that BFA caused the formation of tubular lysosomes, although the kinetics and extent of tubulation varied greatly between different cell types. The BFA-induced tubular lysosomes were often seen to form simple networks. Formation of tubular lysosomes was microtubule-mediated and energy-dependent; interestingly, however, maintenance of the tubulated lysosomes only required microtubules and was insensitive to energy poisons. Upon removal of BFA, the tubular lysosomes rapidly recovered in an energy-dependent process. In most cell types examined, the extensive TGN/EE network is ephemeral, eventually collapsing into a compact cluster of tubulo-vesicular membranes in a process that precedes the formation of tubular lysosomes. However, in primary bovine testicular cells, the BFA-induced TGN/EE network was remarkably stable (for > 12 h). During this time, the TGN/EE network coexisted with tubular lysosomes, however, the two compartments remained completely separate. These results show that BFA has multiple, profound effects on the morphology of various compartments of the endosome-lysosome system. In spite of these changes, endocytic traffic can continue through the altered compartments suggesting that transport occurs through noncoated vesicles or through vesicles that are insensitive to BFA.

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