scholarly journals A distinct class of intracellular storage vesicles, identified by expression of the glucose transporter GLUT4.

1994 ◽  
Vol 91 (26) ◽  
pp. 12750-12754 ◽  
Author(s):  
G. A. Herman ◽  
F. Bonzelius ◽  
A. M. Cieutat ◽  
R. B. Kelly
Keyword(s):  
Glucose Transporter ◽  
Distinct Class ◽  
Storage Vesicles ◽  
Intracellular Storage ◽  
Glucose Transporter Glut4

A dual role of the N-terminal FQQI motif in GLUT4 trafficking

2009 ◽  
Vol 390 (9) ◽  
Author(s):  
Ulrike Bernhardt ◽  
Françoise Carlotti ◽  
Rob C. Hoeben ◽  
Hans-Georg Joost ◽  
Hadi Al-Hasani
Keyword(s):  
Cell Surface ◽  
Glucose Transporter ◽  
Dual Role ◽  
Endosomal Trafficking ◽  
Endosomal Sorting ◽  
Storage Compartment ◽  
Storage Vesicles ◽  
Intracellular Storage ◽  
Glucose Transporter Glut4

AbstractIn adipocytes, the glucose transporter GLUT4 recycles between intracellular storage vesicles and the plasma membrane. GLUT4 is internalized by a clathrin- and dynamin-dependent mechanism, and sorted into an insulin-sensitive storage compartment. Insulin stimulation leads to GLUT4 accumulation on the cell surface. The N-terminal F5QQI motif in GLUT4 has been shown previously to be required for sorting of the protein in the basal state. Here, we show that the FQQI motif is a binding site for the medium chain adaptin μ1, a subunit of the AP-1 adaptor complex that plays a role in post-Golgi/endosomal trafficking events. In order to investigate the role of AP-1 and AP-2 in GLUT4 trafficking, we generated 3T3-L1 adipocytes expressing HA-GLUT4-GFP and knocked down the AP-1 and AP-2 complex by RNAi, respectively. In AP-1 and AP-2 knockdown adipocytes, GLUT4 accumulates at the cell surface in the basal state, consistent with a role of AP-1 in post-endosomal sorting of GLUT4 to the insulin-sensitive storage compartment, and of AP-2 in clathrin-mediated endocytosis. Our data demonstrate a dual role of the F5QQI motif and support the conclusion that the AP complexes direct GLUT4 trafficking and endocytosis.

scholarly journals Characterization of Insulin-Responsive GLUT4 Storage Vesicles Isolated from 3T3-L1 Adipocytes

2000 ◽  
Vol 20 (1) ◽  
pp. 416-427 ◽  
Author(s):  
Mitsuru Hashiramoto ◽  
David E. James
Keyword(s):  
Glucose Transporter ◽  
Significant Proportion ◽  
Protein Composition ◽  
Cell Types ◽  
Storage Compartment ◽  
Storage Vesicles ◽  
Equilibrium Sedimentation ◽  
Insulin Responsiveness ◽  
Glucose Transporter Glut4 ◽  
Golgi Network

ABSTRACT Insulin regulates glucose transport in muscle and adipose tissue by triggering the translocation of a facilitative glucose transporter, GLUT4, from an intracellular compartment to the cell surface. It has previously been suggested that GLUT4 is segregated between endosomes, the trans-Golgi network (TGN), and a postendosomal storage compartment. The aim of the present study was to isolate the GLUT4 storage compartment in order to determine the relationship of this compartment to other organelles, its components, and its presence in different cell types. A crude intracellular membrane fraction was prepared from 3T3-L1 adipocytes and subjected to iodixanol equilibrium sedimentation analysis. Two distinct GLUT4-containing vesicle peaks were resolved by this procedure. The lighter of the two peaks (peak 2) was comprised of two overlapping peaks: peak 2b contained recycling endosomal markers such as the transferrin receptor (TfR), cellubrevin, and Rab4, and peak 2a was enriched in TGN markers (syntaxin 6, the cation-dependent mannose 6-phosphate receptor, sortilin, and sialyltransferase). Peak 1 contained a significant proportion of GLUT4 with a smaller but significant amount of cellubrevin and relatively little TfR. In agreement with these data, internalized transferrin (Tf) accumulated in peak 2 but not peak 1. There was a quantitatively greater loss of GLUT4 from peak 1 than from peak 2 in response to insulin stimulation. These data, combined with the observation that GLUT4 became more sensitive to ablation with Tf-horseradish peroxidase following insulin treatment, suggest that the vesicles enriched in peak 1 are highly insulin responsive. Iodixanol gradient analysis of membranes isolated from other cell types indicated that a substantial proportion of GLUT4 was targeted to peak 1 in skeletal muscle, whereas in CHO cells most of the GLUT4 was targeted to peak 2. These results indicate that in insulin-sensitive cells GLUT4 is targeted to a subpopulation of vesicles that appear, based on their protein composition, to be a derivative of the endosome. We suggest that the biogenesis of this compartment may mediate withdrawal of GLUT4 from the recycling system and provide the basis for the marked insulin responsiveness of GLUT4 that is unique to muscle and adipocytes.

scholarly journals Phosphatidylinositol 4-kinase, but not phosphatidylinositol 3-kinase, is present in GLUT4-containing vesicles isolated from rat skeletal muscle

1998 ◽  
Vol 335 (2) ◽  
pp. 351-356 ◽  
Author(s):  
S⊘ren KRISTIANSEN ◽  
Toolsie RAMLAL ◽  
Amira KLIP
Keyword(s):  
Skeletal Muscle ◽  
Glucose Transporter ◽  
Kinase Activity ◽  
Surface Membrane ◽  
Fold Increase ◽  
Rat Skeletal Muscle ◽  
Membrane Compartment ◽  
Intracellular Storage ◽  
Glucose Transporter Glut4 ◽  
Adipose Cells

Insulin stimulates the rate of glucose transport into muscle and adipose cells by translocation of glucose transporter (GLUT4)-containing vesicles from an intracellular storage pool to the surface membrane. This event is mediated through the insulin receptor substrates (IRSs), which in turn activate phosphatidylinositol (PI) 3-kinase isoforms. It has been suggested that insulin causes attachment of PI 3-kinases to the intracellular GLUT4-containing vesicles in rat adipose cells. Furthermore, it has also been shown that GLUT4-containing vesicles in adipose cells contain a PI 4-kinase. In the present study we investigate whether GLUT4-containing vesicles isolated from rat skeletal muscle display PI 3-kinase and/or PI 4-kinase activities. Insulin stimulation caused a rapid increase (5–15-fold increase compared with control) in the intracellular cytosolic IRS-1-associated PI-3 kinase activity. This PI 3-kinase activity was also present in a membrane preparation containing the insulin-regulatable pool of GLUT4 transporters. However, when GLUT4-containing vesicles were isolated by immunoprecipitation from basal and insulin-stimulated (3 min) skeletal muscle, the vesicles displayed PI 4-kinase, but not PI 3-kinase, activity. Insulin did not regulate the PI 4-kinase activity in the GLUT4-containing vesicles. In conclusion, GLUT4-containing vesicles from rat skeletal muscle contain a PI 4-kinase, but not a PI 3-kinase. It is suggested that, in skeletal muscle, insulin causes activation of the IRS/PI 3-kinase complex in an intracellular membrane compartment associated closely with the GLUT4-containing vesicles, but not in the GLUT4-containing vesicles themselves.

scholarly journals Insulin-stimulated exocytosis of GLUT4 is enhanced by IRAP and its partner tankyrase

2007 ◽  
Vol 402 (2) ◽  
pp. 279-290 ◽  
Author(s):  
Tsung-Yin J. Yeh ◽  
Juan I. Sbodio ◽  
Zhi-Yang Tsun ◽  
Biao Luo ◽  
Nai-Wen Chi
Keyword(s):  
Protein Modification ◽  
Glucose Transporter ◽  
Glut4 Translocation ◽  
Small Interfering Rnas ◽  
Insulin Stimulation ◽  
Storage Vesicles ◽  
Cargo Proteins ◽  
Polymerase Inhibitor ◽  
Parp Activity ◽  
Glucose Transporter Glut4

The glucose transporter GLUT4 and the aminopeptidase IRAP (insulin-responsive aminopeptidase) are the major cargo proteins of GSVs (GLUT4 storage vesicles) in adipocytes and myocytes. In the basal state, most GSVs are sequestered in perinuclear and other cytosolic compartments. Following insulin stimulation, GSVs undergo exocytic translocation to insert GLUT4 and IRAP into the plasma membrane. The mechanisms regulating GSV trafficking are not fully defined. In the present study, using 3T3-L1 adipocytes transfected with siRNAs (small interfering RNAs), we show that insulin-stimulated IRAP translocation remained intact despite substantial GLUT4 knockdown. By contrast, insulin-stimulated GLUT4 translocation was impaired upon IRAP knockdown, indicating that IRAP plays a role in GSV trafficking. We also show that knockdown of tankyrase, a Golgi-associated IRAP-binding protein that co-localizes with perinuclear GSVs, attenuated insulin-stimulated GSV translocation and glucose uptake without disrupting insulin-induced phosphorylation cascades. Moreover, iodixanol density gradient analyses revealed that tankyrase knockdown altered the basal-state partitioning of GLUT4 and IRAP within endosomal compartments, apparently by shifting both proteins toward less buoyant compartments. Importantly, the afore-mentioned effects of tankyrase knockdown were reproduced by treating adipocytes with PJ34, a general PARP (poly-ADP-ribose polymerase) inhibitor that abrogated tankyrase-mediated protein modification known as poly-ADP-ribosylation. Collectively, these findings suggest that physiological GSV trafficking depends in part on the presence of IRAP in these vesicles, and that this process is regulated by tankyrase and probably its PARP activity.

scholarly journals A Rab10:RalA G protein cascade regulates insulin-stimulated glucose uptake in adipocytes

2014 ◽  
Vol 25 (19) ◽  
pp. 3059-3069 ◽  
Author(s):  
Sheelarani Karunanithi ◽  
Tingting Xiong ◽  
Maeran Uhm ◽  
Dara Leto ◽  
Jingxia Sun ◽  
...  
Keyword(s):  
Glucose Uptake ◽  
G Protein ◽  
Glucose Transporter ◽  
Nucleotide Exchange ◽  
Nucleotide Exchange Factor ◽  
Storage Vesicles ◽  
Membrane Compartments ◽  
Bona Fide ◽  
Glucose Transporter Glut4 ◽  
Protein Kinase Akt

Insulin-stimulated glucose uptake in fat and muscle is mediated by the major facilitative glucose transporter Glut4. Insulin controls the trafficking of Glut4 to the plasma membrane via regulation of a series of small G proteins, including RalA and Rab10. We demonstrate here that Rab10 is a bona fide target of the GTPase-activating protein AS160, which is inhibited after phosphorylation by the protein kinase Akt. Once activated, Rab10 can increase the GTP binding of RalA by recruiting the Ral guanyl nucleotide exchange factor, Rlf/Rgl2. Rab10 and RalA reside in the same pool of Glut4-storage vesicles in untreated cells, and, together with Rlf, they ensure maximal glucose transport. Overexpression of membrane-tethered Rlf compensates for the loss of Rab10 in Glut4 translocation, suggesting that Rab10 recruits Rlf to membrane compartments for RalA activation and that RalA is downstream of Rab10. Together these studies identify a new G protein cascade in the regulation of insulin-stimulated Glut4 trafficking and glucose uptake.

C2C12 myocytes lack an insulin-responsive vesicular compartment despite dexamethasone-induced GLUT4 expression

2002 ◽  
Vol 283 (3) ◽  
pp. E514-E524 ◽  
Author(s):  
Lori L. Tortorella ◽  
Paul F. Pilch
Keyword(s):  
Glucose Transporter ◽  
Fold Increase ◽  
Snare Proteins ◽  
Vesicular Traffic ◽  
Glut4 Expression ◽  
Protein Receptor ◽  
Syntaxin 4 ◽  
Insulin Dependent ◽  
Glucose Transporter Glut4 ◽  
Vesicular Compartment

Insulin regulates the uptake of glucose into skeletal muscle and adipocytes by redistributing the tissue-specific glucose transporter GLUT4 from intracellular vesicles to the cell surface. To date, GLUT4 is the only protein involved in insulin-regulated vesicular traffic that has this tissue distribution, thus raising the possibility that its expression alone may allow formation of an insulin-responsive vesicular compartment. We show here that treatment of differentiating C2C12myoblasts with dexamethasone, acting via the glucocorticoid receptor, causes a ≥10-fold increase in GLUT4 expression but results in no significant change in insulin-stimulated glucose transport. Signaling from the insulin receptor to its target, Akt2, and expression of the soluble N-ethylmaleimide-sensitive factor-attachment protein receptor, or SNARE, proteins syntaxin 4 and vesicle-associated membrane protein are normal in dexamethasone-treated C2C12 cells. However, these cells show no insulin-dependent trafficking of the insulin-responsive aminopeptidase or the transferrin receptor, respective markers for intracellular GLUT4-rich compartments and endosomes that are insulin responsive in mature muscle and adipose cells. Therefore, these data support the hypothesis that GLUT4 expression by itself is insufficient to establish an insulin-sensitive vesicular compartment.

scholarly journals Transcriptional repression of the mouse insulin-responsive glucose transporter (GLUT4) gene by cAMP.

1991 ◽  
Vol 88 (5) ◽  
pp. 1933-1937 ◽  
Author(s):  
K. H. Kaestner ◽  
J. R. Flores-Riveros ◽  
J. C. McLenithan ◽  
M. Janicot ◽  
M. D. Lane
Keyword(s):  
Transcriptional Repression ◽  
Glucose Transporter ◽  
Glucose Transporter Glut4

scholarly journals GLUT4 Recycles via a trans-Golgi Network (TGN) Subdomain Enriched in Syntaxins 6 and 16 But Not TGN38: Involvement of an Acidic Targeting Motif

2003 ◽  
Vol 14 (3) ◽  
pp. 973-986 ◽  
Author(s):  
Annette M. Shewan ◽  
Ellen M. van Dam ◽  
Sally Martin ◽  
Tang Bor Luen ◽  
Wanjin Hong ◽  
...  
Keyword(s):  
Cell Surface ◽  
Glucose Transporter ◽  
Adipocyte Differentiation ◽  
Attachment Protein ◽  
Trans Golgi Network ◽  
Sensitive Factor ◽  
Protein Receptors ◽  
Glucose Transporter Glut4 ◽  
Golgi Network ◽  
Endosomal System

Insulin stimulates glucose transport in fat and muscle cells by triggering exocytosis of the glucose transporter GLUT4. To define the intracellular trafficking of GLUT4, we have studied the internalization of an epitope-tagged version of GLUT4 from the cell surface. GLUT4 rapidly traversed the endosomal system en route to a perinuclear location. This perinuclear GLUT4 compartment did not colocalize with endosomal markers (endosomal antigen 1 protein, transferrin) or TGN38, but showed significant overlap with the TGN target (t)-solubleN-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) Syntaxins 6 and 16. These results were confirmed by vesicle immunoisolation. Consistent with a role for Syntaxins 6 and 16 in GLUT4 trafficking we found that their expression was up-regulated significantly during adipocyte differentiation and insulin stimulated their movement to the cell surface. GLUT4 trafficking between endosomes and trans-Golgi network was regulated via an acidic targeting motif in the carboxy terminus of GLUT4, because a mutant lacking this motif was retained in endosomes. We conclude that GLUT4 is rapidly transported from the cell surface to a subdomain of thetrans-Golgi network that is enriched in the t-SNAREs Syntaxins 6 and 16 and that an acidic targeting motif in the C-terminal tail of GLUT4 plays an important role in this process.

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