scholarly journals Phosphoinositides in insulin action on GLUT4 dynamics: not just PtdIns(3,4,5)P3

2008 ◽  
Vol 295 (3) ◽  
pp. E536-E544 ◽  
Author(s):  
Assia Shisheva
Keyword(s):  
Plasma Membrane ◽  
Cell Surface ◽  
Insulin Receptor ◽  
Experimental Evidence ◽  
Functional Significance ◽  
Insulin Action ◽  
Complementary Function ◽  
Intracellular Storage ◽  
Insulin Responsiveness ◽  
Rate Limiting

Accumulated evidence over the last several years indicates that insulin regulates multiple steps in the overall translocation of GLUT4 vesicles to the fat/muscle cell surface, including formation of an intracellular storage pool of GLUT4 vesicles, its movement to the proximity of the cell surface, and the subsequent docking/fusion with the plasma membrane. Insulin-stimulated formation of phosphatidylinositol 3,4,5-trisphosphate [PtdIns(3,4,5)P3; and in some cases, of its catabolite PtdIns(3,4)P2] plays a pivotal role in this process. PtdIns(3,4,5)P3 is synthesized by the activated wortmannin-sensitive class IA phosphoinositide (PI) 3-kinase and controls the rate-limiting cell surface terminal stages of the GLUT4 journey. However, recent research is consistent with the conclusion that signals by each of the remaining five PIs, i.e., PtdIns(3)P, PtdIns(4)P, PtdIns(5)P, PtdIns(3,5)P2, and PtdIns(4,5)P2, may act in concert with that of PtdIns(3,4,5)P3 in integrating the insulin receptor-issued signals with GLUT4 surface translocation and glucose transport activation. This review summarizes the experimental evidence supporting the complementary function of these PIs in insulin responsiveness of fat and muscle cells, with particular reference to mechanistic insights and functional significance in the regulation of overall GLUT4 vesicle dynamics.

scholarly journals Association of phosphatidylinositol 3-kinase with the insulin receptor: compartmentation in rat liver

2000 ◽  
Vol 279 (2) ◽  
pp. E266-E274 ◽  
Author(s):  
Paul G. Drake ◽  
Alejandro Balbis ◽  
Jiong Wu ◽  
John J. M. Bergeron ◽  
Barry I. Posner
Keyword(s):  
Plasma Membrane ◽  
Cell Surface ◽  
Insulin Receptor ◽  
Rat Liver ◽  
Intracellular Signaling ◽  
Kinase Activity ◽  
Glycogen Synthase ◽  
Metabolic Effects ◽  
Phosphatidylinositol 3 Kinase ◽  
Phosphatidylinositol 3

Phosphatidylinositol 3-kinase (PI 3-kinase) plays an important role in a variety of hormone and growth factor-mediated intracellular signaling cascades and has been implicated in the regulation of a number of metabolic effects of insulin, including glucose transport and glycogen synthase activation. In the present study we have examined 1) the association of PI 3-kinase with the insulin receptor kinase (IRK) in rat liver and 2) the subcellular distribution of PI 3-kinase-IRK interaction. Insulin treatment promoted a rapid and pronounced recruitment of PI 3-kinase to IRKs located at the plasma membrane, whereas no increase in association with endosomal IRKs was observed. In contrast to IRS-1-associated PI 3-kinase activity, association of PI 3-kinase with the plasma membrane IRK did not augment the specific activity of the lipid kinase. With use of the selective PI 3-kinase inhibitor wortmannin, our data suggest that the cell surface IRK β-subunit is not a substrate for the serine kinase activity of PI 3-kinase. The functional significance for the insulin-stimulated selective recruitment of PI 3-kinase to cell surface IRKs remains to be elucidated.

Evidence for modulation of insulin action and degradation independently of insulin binding

1981 ◽  
Vol 240 (3) ◽  
pp. E325-E332
Author(s):  
J. F. Caro ◽  
J. M. Amatruda
Keyword(s):  
Plasma Membrane ◽  
Insulin Receptor ◽  
Insulin Action ◽  
Insulin Binding ◽  
Isolated Hepatocytes ◽  
Insulin Degradation ◽  
Acetate Incorporation ◽  
Large Excess ◽  
Receptor Antibody

The interrelationships between insulin binding, action, and degradation were investigated in isolated hepatocytes with the aid of an insulin-receptor antibody (IRA) preparation that does not affect insulin binding. These IRA have insulin-like effects as determined by their ability to stimulate [14C]acetate incorporation into lipids. However, this effect is less than that of insulin; and in the presence of insulin and IRA, the effects of insulin are partially inhibited. The IRA have no effect on lipogenesis stimulated by postreceptor insulin "mimickers." The IRA also significantly inhibit insulin degradation. However, they do not affect insulin degradation in the presence of a large excess of unlabeled hormone. Taken together these data demonstrate that insulin action and degradation can be modulated independently of binding and suggest that the IRA partially inhibit insulin action and degradation through a portion of the insulin receptor that is not a determinant of insulin binding. It is possible, however, that there exist in the antiserum heterogeneous antibodies that bind to nonreceptor sites on the plasma membrane and mediate some of the phenomena observed.

Role of sialic acid in insulin action and the insulin resistance of diabetes mellitus

1988 ◽  
Vol 255 (2) ◽  
pp. E173-E179 ◽  
Author(s):  
A. I. Salhanick ◽  
J. M. Amatruda
Keyword(s):  
Diabetes Mellitus ◽  
Insulin Resistance ◽  
Sialic Acid ◽  
Cell Surface ◽  
Acid Content ◽  
Insulin Action ◽  
Diabetic Rats ◽  
Hepatic Insulin Resistance ◽  
Sialic Acid Content ◽  
Insulin Responsiveness

Adipocytes treated with neuraminidase show markedly reduced responsiveness to insulin without any alteration in insulin binding. In addition, several studies have separately demonstrated both insulin resistance and decreases in membrane sialic acid content and associated biosynthetic enzymes in diabetes mellitus. In the present study, we investigated the role that sialic acid residues may play in insulin action and in the hepatic insulin resistance associated with nonketotic diabetes. Primary cultures of hepatocytes from normal rats treated with neuraminidase demonstrated a dose-dependent decrease in insulin-stimulated lipogenesis. At a concentration of neuraminidase that decreases insulin action by 50%, 23% of total cellular sialic acid content was released. Neuraminidase-releasable sialic acid was significantly decreased in hepatocytes from diabetic rats and this was associated with significant insulin resistance. Treatment of hepatocytes from diabetic rats with cytidine 5'-monophospho-N-acetylneuraminic acid (CMP-NANA) enhanced insulin responsiveness 39%. The enhanced insulin responsiveness induced by CMP-NANA was blocked by cytidine 5'-monophosphate (CMP) suggesting that the CMP-NANA effect was catalyzed by a cell surface sialyltransferase. CMP reduced neuraminidase-releasable [14C]sialic acid incorporation into hepatocytes by 43%. The data demonstrate a role for cell surface sialic acid residues in hepatic insulin action and support a role for decreased cell surface sialic acid residues in the insulin resistance of diabetes mellitus.

scholarly journals Multiple endosomal recycling pathways in rat adipose cells

1998 ◽  
Vol 331 (3) ◽  
pp. 829-835 ◽  
Author(s):  
Konstantin V. KANDROR ◽  
Paul F. PILCH
Keyword(s):  
Plasma Membrane ◽  
Cell Surface ◽  
Insulin Receptor ◽  
Transferrin Receptor ◽  
Glucose Transporter ◽  
Sedimentation Coefficient ◽  
Membrane Vesicles ◽  
Average Diameter ◽  
Subcellular Fractionation ◽  
Adipose Cells

Adipose and skeletal-muscle cells can translocate several membrane proteins from intracellular compartment(s) to the cell surface in an insulin-dependent fashion. Among these proteins is Glut4, a physiologically important glucose transporter which mediates insulin's effect on blood glucose clearance. Under basal conditions, Glut4 is localized in uniform, intracellular membrane vesicles with an average diameter of 50–70 nm and a sedimentation coefficient of 100–120 S. The nature of this compartment and its trafficking pathway to the plasma membrane is still unresolved. We show here that, in addition to Glut4, the aminopeptidase gp160 or insulin-responsive aminopeptidase (‘IRAP’), sortilin, and an acutely recycling population of the insulin-like growth factor-II/mannose 6-phosphate receptor, this compartment includes 60% of the intracellular population of the transferrin receptor. We used subcellular fractionation, cell-surface biotinylation, and radioactive-ligand (125I-transferrin) uptake to demonstrate that the transferrin receptor recycles between this compartment and the plasma membrane in response to insulin along with Glut4 and other protein components of these vesicles. The co-localization of Glut4 and several endosomal markers in the terminally differentiated fat-cells during several stages of their cycling pathways suggests that the ‘Glut4 pathway ’ may derive from the hormone-insensitive endosomes of undifferentiated preadipocytes. The insulin receptor is excluded from Glut4-containing vesicles in both insulin-stimulated and unstimulated adipocytes, and thus it is likely to traffic independently from Glut4 through different intracellular compartments. Our data show that, in adipose cells, the ligand-dependent recycling pathway of the insulin receptor is structurally separated from the ligand-independent pathway of the transferrin receptor, and that Glut4 is specifically targetted to the latter.

scholarly journals High basal cell surface levels of fish GLUT4 are related to reduced sensitivity of insulin-induced translocation toward GGA and AS160 inhibition in adipocytes

2010 ◽  
Vol 298 (2) ◽  
pp. E329-E336 ◽  
Author(s):  
Encarnación Capilla ◽  
Mònica Díaz ◽  
June Chunqiu Hou ◽  
Josep V. Planas ◽  
Jeffrey E. Pessin
Keyword(s):  
Plasma Membrane ◽  
Cell Surface ◽  
Basal Cell ◽  
Protein Motifs ◽  
Similar Profile ◽  
Amino Terminal ◽  
Glut4 Expression ◽  
Trafficking Pathway ◽  
Insulin Responsiveness ◽  
Regulated Trafficking

Glucose entry into cells is mediated by a family of facilitative transporter proteins (GLUTs). In mammals, GLUT4 is expressed in insulin-sensitive tissues and is responsible for the postprandial uptake of glucose. In fish, GLUT4 also mediates insulin-regulated glucose entry into cells but differs from mammalian GLUT4 in its affinity for glucose and in protein motifs known to be important for the traffic of GLUT4. In this study, we have characterized the intracellular and plasma membrane (PM) traffic of two orthologs of GLUT4 in fish, trout (btGLUT4) and salmon (okGLUT4), that do not share the amino terminal FQQI targeting motif of mammalian GLUT4. btGLUT4 (FQHL) and, to a lesser extent, okGLUT4 (FQQL) showed higher basal PM levels, faster traffic to the PM after biosynthesis, and earlier acquisition of insulin responsiveness than rat GLUT4. Furthermore, btGLUT4 showed a similar profile of internalization than rat GLUT4. Expression of the dominant-interfering AS160-4P mutant caused a significant decrease in the insulin-induced PM levels of okGLUT4 and rat GLUT4 and, to a lesser extent, of btGLUT4, suggesting that btGLUT4 has reduced retention into the IRC. Contrary to rat GLUT4 and okGLUT4, the presence of btGLUT4 at the PM under insulin-stimulated conditions was not affected by coexpression of a dominant-interfering GGA mutant. These data suggest that fish GLUT4 follow a different trafficking pathway to the PM compared with rat GLUT4 that seems to be relatively independent of GGA. These results indicate that the regulated trafficking characteristics of GLUT4 have been modified during evolution from fish to mammals.

scholarly journals Distinct signals in the GLUT4 glucose transporter for internalization and for targeting to an insulin-responsive compartment.

1995 ◽  
Vol 130 (5) ◽  
pp. 1071-1079 ◽  
Author(s):  
K J Verhey ◽  
J I Yeh ◽  
M J Birnbaum
Keyword(s):  
Amino Acids ◽  
Plasma Membrane ◽  
Cell Surface ◽  
Glucose Transporter ◽  
Storage Site ◽  
Dileucine Motif ◽  
Pool Model ◽  
Intracellular Storage ◽  
Intracellular Sequestration ◽  
Hormone Responsiveness

In adipose and muscle cells, insulin stimulates a rapid and dramatic increase in glucose uptake, primarily by promoting the redistribution of the GLUT4 glucose transporter from its intracellular storage site to the plasma membrane. In contrast, the more ubiquitously expressed isoform GLUT1 is localized at the cell surface in the basal state, and shows a less dramatic translocation in response to insulin. To identify sequences involved in the differential subcellular localization and hormone-responsiveness of these isoforms, chimeric GLUT1/GLUT4 transporters were stably expressed in mouse 3T3-L1 adipocytes. The NH2 terminus of GLUT4 contains sequences capable of sequestering the transporter inside the cell, although not in an insulin-sensitive pool. In contrast, the COOH-terminal 30 amino acids of GLUT4 are sufficient for its correct localization to an intracellular storage pool which translocates to the cell surface in response to insulin. The dileucine motif within this domain, which is required for intracellular sequestration of chimeric transporters in fibroblasts, is not critical for targeting to the hormone-responsive compartment in adipocytes. Analysis of rates of internalization of chimeric transporter after the removal of insulin from cells, as well as the subcellular distribution of transporters in cells unexposed to or treated with insulin, leads to a three-pool model which can account for the data.

scholarly journals Knockout of Syntaxin-4 in 3T3-L1 adipocytes reveals new insight into GLUT4 trafficking and adiponectin secretion

2021 ◽  
Author(s):  
Hannah L. Black ◽  
Rachel Livingstone ◽  
Cynthia C. Mastick ◽  
Mohammed Al Tobi ◽  
Holly Taylor ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Cell Surface ◽  
Glucose Transport ◽  
Metabolic Regulation ◽  
Glucose Transporter ◽  
Ectopic Expression ◽  
Glut4 Translocation ◽  
Syntaxin 4 ◽  
Rate Limiting ◽  
Insight Into

Adipocytes are key to metabolic regulation, exhibiting insulin-stimulated glucose transport which is underpinned by the insulin-stimulated delivery of glucose transporter-4 (GLUT4)- containing vesicles to the plasma membrane where they dock and fuse increasing cell surface GLUT4 levels. Adipocytokines such as adiponectin are secreted via a similar mechanism. We used genome editing to knockout Syntaxin-4 a protein reported to mediate GLUT4-vesicle fusion with the plasma membrane in 3T3-L1 adipocytes. Syntaxin-4 knockout reduced insulin-stimulated glucose transport and adiponectin secretion by ∼50% and reduced GLUT4 levels. Ectopic expression of HA-GLUT4-GFP showed that Syntaxin-4 knockout cells retain significant GLUT4 translocation capacity demonstrating that Syntaxin-4 is dispensable for insulin-stimulated GLUT4 translocation. Analysis of recycling kinetics revealed only a modest reduction in the exocytic rate of GLUT4 in knockout cells, and little effect on endocytosis. These analyses demonstrate that Syntaxin-4 is not always rate limiting for GLUT4 delivery to the cell surface. In sum, we show that Syntaxin-4 knockout results in reduced insulin-stimulated glucose transport, depletion of cellular GLUT4 levels and inhibition of adiponectin secretion but has only modest effects on the translocation capacity of the cells.

scholarly journals Insulin-induced receptor loss in the cultured human lymphocyte: quantitative morphological perturbations in the cell and plasma membrane

1979 ◽  
Vol 39 (1) ◽  
pp. 77-88
Author(s):  
P. Gordon ◽  
J.L. Carpentier ◽  
E. Van Obberghen ◽  
P. Barazzone ◽  
J. Roth ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Plasma Membrane ◽  
Horseradish Peroxidase ◽  
Cell Surface ◽  
Insulin Receptor ◽  
Human Lymphocyte ◽  
Human Lymphocytes ◽  
Experimental Conditions ◽  
Peroxidase Uptake

When cultured human lymphocytes (IM-9) are exposed to 10(−6) M procine insulin for 6 h, washed, and incubated with 125I-insulin, the ability of the cell to bind the labelled hormone is reduced by a mean of 78%. Under these experimental conditions that induce insulin-receptor loss in this cell there is a mean 95% increase in microinvaginations in the plasma membrane revealed by electron microscopy on freez-fractured replicas of the cell. At the same time, horseradish peroxidase uptake, a marker of endocytosis, is increased in the cells incubated with insulin. Coupled with our recent EM autoradiographic evidence that labelled insulin is acutely internalized by this cell, these studies are consistent with the possibility that endocytosis represents a mechanism by which receptor is removed from the cell surface.

Insulin binding and action on fat cells from young healthy females and males

1982 ◽  
Vol 243 (2) ◽  
pp. E158-E167 ◽  
Author(s):  
O. Pedersen ◽  
E. Hjollund ◽  
H. O. Lindskov
Keyword(s):  
Glucose Metabolism ◽  
Cell Surface ◽  
Insulin Receptor ◽  
Glucose Transport ◽  
Receptor Binding ◽  
Glucose Utilization ◽  
Insulin Binding ◽  
Fat Cells ◽  
Insulin Receptor Binding ◽  
Rate Limiting

Insulin binding and action were studied in fat cells from the gluteal region of young healthy subjects. Fat cells from females were larger than those of males, had higher insulin receptor binding and higher rates of noninsulin-stimulated and maximally insulin-stimulated rates of methylglucose transport and glucose metabolism when these data were expressed per cell number. However, when insulin binding and insulin effects were expressed per cell surface, which may be physiologically more relevant, no sex differences were found in insulin binding and glucose transport, whereas noninsulin-stimulated and maximally insulin-stimulated glucose metabolism was still significantly increased in female fat cells. The latter indicates postreceptor differences in glucose metabolism between females and males. The insulin concentrations causing half-maximal responses (a measure of the sensitivity to insulin) of glucose transport, glucose metabolism and lipolysis were similar in fat cells from the two sexes, which is consistent with the comparable values of insulin receptor binding when adjusted to cell surface. Studies of rate-determining steps for the glucose utilization of human fat cells showed that glucose transport was not the rate-limiting step at physiological glucose concentrations. Moreover, at physiological glucose levels, glucose metabolism exhibited a decreased maximal insulin responsiveness and an increased insulin sensitivity when compared with glucose metabolism at low glucose concentrations at which glucose transport is rate limiting for the fat cell glucose utilization.

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