Temperature optimum of insulin-stimulated 2-deoxy-d-glucose uptake in rat adipocytes. Correlation of cellular transport with membrane spin-label and fluorescence-label data

The effects of temperature alterations between 22 degrees C and 48 degrees C on basal and insulin-stimulated 2-deoxy-D-[1-14C]glucose uptake were examined in isolated rat adipocytes. A distinct optimum was found near physiological temperature for uptake in the presence of maximally effective insulin concentrations where insulin stimulation and hexose uptake were both conducted at each given assay temperature. Basal uptake was only subtly affected. Control and maximally insulin-stimulated cells incubated at 35 degrees C subsequently exhibited minimal temperature-sensitivity of uptake measured between 30 and 43 degrees C. The data are mostly consistent with the concept that insulin-sensitive glucose transporters are, after stimulation by insulin, functionally similar to basal transporters. Adipocyte plasma membranes were labelled with various spin- and fluorescence-label probes in lipid structural studies. The temperature-dependence of the order parameter S calculated from membranes labelled with 5-nitroxide stearate indicated the presence of a lipid phase change at approx. 33 degrees C. Membranes labelled with the fluorescence label 1,6-diphenylhexa-1,3,5-triene, or the cholesterol-like spin label nitroxide cholestane, reveal sharp transitions at lower temperatures. We suggest that a thermotropic lipid phase separation occurs in the adipocyte membrane that may be correlated with the temperature-dependence of hexose transport and insulin action in the intact cells.

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Effects of adenosine derivatives on cAMP accumulation and lipolysis in rat adipocytes and on adenylate cyclase in adipocyte plasma membranes

Naunyn-Schmiedeberg s Archives of Pharmacology ◽

10.1007/bf00508634 ◽

1977 ◽

Vol 299 (1) ◽

pp. 33-40 ◽

Cited By ~ 49

Author(s):

Thomas Trost ◽

Klaus Stock

Keyword(s):

Adenylate Cyclase ◽

Plasma Membranes ◽

Camp Accumulation ◽

Rat Adipocytes ◽

Adenosine Derivatives ◽

Adipocyte Plasma Membranes

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Protein sorting by lipid phase-like domains supports emergent signaling function in B lymphocyte plasma membranes

eLife ◽

10.7554/elife.19891 ◽

2017 ◽

Vol 6 ◽

Cited By ~ 83

Author(s):

Matthew B Stone ◽

Sarah A Shelby ◽

Marcos F Núñez ◽

Kathleen Wisser ◽

Sarah L Veatch

Keyword(s):

Plasma Membranes ◽

B Lymphocyte ◽

Membrane Lipids ◽

Super Resolution ◽

Cell Receptor ◽

Biochemical Networks ◽

Lipid Phase ◽

Intact Cells ◽

Signaling Function ◽

Liquid Ordered

Diverse cellular signaling events, including B cell receptor (BCR) activation, are hypothesized to be facilitated by domains enriched in specific plasma membrane lipids and proteins that resemble liquid-ordered phase-separated domains in model membranes. This concept remains controversial and lacks direct experimental support in intact cells. Here, we visualize ordered and disordered domains in mouse B lymphoma cell membranes using super-resolution fluorescence localization microscopy, demonstrate that clustered BCR resides within ordered phase-like domains capable of sorting key regulators of BCR activation, and present a minimal, predictive model where clustering receptors leads to their collective activation by stabilizing an extended ordered domain. These results provide evidence for the role of membrane domains in BCR signaling and a plausible mechanism of BCR activation via receptor clustering that could be generalized to other signaling pathways. Overall, these studies demonstrate that lipid mediated forces can bias biochemical networks in ways that broadly impact signal transduction.

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Differential effects of insulin, antibodies against rat adipocyte plasma membranes, and other agents that mimic insulin action in rat adipocytes

Metabolism ◽

10.1016/0026-0495(85)90072-1 ◽

1985 ◽

Vol 34 (11) ◽

pp. 1012-1019 ◽

Cited By ~ 3

Author(s):

Dennis J. Pillion

Keyword(s):

Insulin Action ◽

Plasma Membranes ◽

Insulin Antibodies ◽

Differential Effects ◽

Rat Adipocytes ◽

Adipocyte Plasma Membranes

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Chronic ethanol feeding impairs endothelin-1-stimulated glucose uptake via decreased Gα11 expression in rat adipocytes

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00547.2002 ◽

2003 ◽

Vol 285 (2) ◽

pp. E303-E310 ◽

Cited By ~ 6

Author(s):

Nadia Rachdaoui ◽

Becky M. Sebastian ◽

Laura E. Nagy

Keyword(s):

Glucose Uptake ◽

Plasma Membranes ◽

Ethanol Exposure ◽

Chronic Ethanol ◽

Endothelin 1 ◽

Rat Adipocytes ◽

Downstream Target ◽

Tyrosine Kinase 2 ◽

Increase Glucose Uptake ◽

Ethanol Feeding

Chronic ethanol feeding decreases insulin-stimulated glucose uptake in rat adipocytes. Here, we show that chronic ethanol also decreases endothelin-stimulated glucose uptake. Endothelin-1 increased uptake of 2-deoxyglucose 2.4-fold in adipocytes isolated from pair-fed rats. However, in adipocytes isolated from rats that had consumed a diet containing 35% ethanol for 4 wk, endothelin-1 did not increase glucose uptake. Although endothelin-1 increased GLUT4 quantity at the plasma membrane in adipocytes from pair-fed rats, there was no increase in GLUT4 after chronic ethanol feeding. Loss of endothelin-1-stimulated glucose uptake after ethanol feeding was associated with a specific decrease in the quantity of Gα11 in plasma membranes, with no change in Gαq quantity. Activation of proline-rich tyrosine kinase 2 (PYK2), a downstream target of Gαq/11 that is required for endothelin-1-stimulated GLUT4 translocation in 3T3-L1 adipocytes, was also suppressed after chronic ethanol feeding. In contrast, activation of p38 MAPK by endothelin-1 was not affected by chronic ethanol exposure. These data demonstrate that chronic ethanol feeding suppresses endothelin-1-stimulated glucose uptake and suggest that decreased expression of Gα11 coupled to impaired endothelin-1-dependent activation of PYK2 contributes to this response.

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Quantity of Na/K-ATPase and glucose transporters in the plasma membrane of rat adipocytes is reduced by in vivo triiodothyronine

Acta Endocrinologica ◽

10.1530/eje.0.1330626 ◽

1995 ◽

Vol 133 (5) ◽

pp. 626-634 ◽

Cited By ~ 10

Author(s):

Marianne Voldstedlund ◽

Jørgen Tranum-Jensen ◽

Aase Handberg ◽

Jørgen Vinten

Keyword(s):

Plasma Membrane ◽

Plasma Membranes ◽

Glucose Transporter ◽

Glucose Transporters ◽

Insulin Stimulation ◽

Rat Adipocytes ◽

Adipocyte Plasma Membranes ◽

Glucose Transporter Glut4

Voldstedlund M. Tranum-Jensen J, Handberg A, Vinten J. Quantity of Na/K-ATPase and glucose transporters in the plasma membrane of rat adipocytes is reduced by in vivo triiodothyronine. Eur J Endocrinol 1995:133:626–34. ISSN 0804–4643 The expression of sodium-potassium pumps and glucose transporters in pure adipocyte plasma membranes from a hyperthyroid animal model was studied. Hyperthyroidism was induced by enteral administration of five doses of 90 μg of triiodothyronine every second day to 8-week-old rats. Following isolation of epididymal adipocytes, 3-O-methylglucose transport was measured and the number of Na/K-ATPase-(α1- and α2-isoforms) and glucose transporter (GLUT1 and GLUT4) molecules in sheets of adipocyte plasma membrane were determined by quantitative immunoelectron microscopy, using gold labelling. Maximal in vitro insulin stimulation of adipocytes increased the glucose transport rate and the amount of GLUT4 in the plasma membrane 15-fold, whereas the amount of α2 was unaffected, In adipocytes from hyperthyroid rats, mean adipocyte volume was decreased by 18% and the quantities of GLUT4 per unit area of plasma membrane (maximal insulin stimulation) and of α2 were decreased by 19% and 15% respectively. Thus, hypotrophia of fat tissue in the hyperthyroid state is associated with a decreased expression in the plasma membrane of the glucose transporter GLUT4 and the α2 -isoform of Na/K-ATPase. Marianne Voldstedlund, Department of Medical Physiology, The Panum Institute, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark

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The effect of membrane composition and alcohols on the insulin-sensitive reconstituted monosaccharide-transport system of rat adipocyte plasma membranes

Biochemical Journal ◽

10.1042/bj2160113 ◽

1983 ◽

Vol 216 (1) ◽

pp. 113-120 ◽

Cited By ~ 11

Author(s):

J E More ◽

M N Jones

Keyword(s):

Fatty Acids ◽

Glucose Uptake ◽

Plasma Membranes ◽

Acyl Chain ◽

Membrane Composition ◽

Monosaccharide Transporter ◽

Acyl Chain Length ◽

Monosaccharide Transport ◽

Phospholipid Acyl Chain ◽

Adipocyte Plasma Membranes

The monosaccharide transporter from the plasma membranes of rat adipocytes and insulin-stimulated adipocytes has been reconstituted in sonicated liposomes. The stereospecific D-glucose uptake by liposomes made from a range of phospholipids and incorporating fatty acids has been investigated. D-Glucose uptake is correlated with an increase in lipid fluidity as a consequence of the addition of fluidizing fatty acids, changes in phospholipid acyl chain length and temperature. Benzyl alcohol and ethyl alcohol, which are generally considered to increase bilayer fluidity, decrease stereo-specific D-glucose uptake in both whole adipocytes and reconstituted liposomes. It is suggested that, although these alcohols may affect D-glucose transport by lipid-mediated fluidity changes, they also interact directly with the transporter resulting in inhibition of transport.

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Identification of high density lipoprotein binding proteins in mature adipocyte plasma membranes

Biochemistry and Cell Biology ◽

10.1139/o93-052 ◽

1993 ◽

Vol 71 (7-8) ◽

pp. 348-354 ◽

Cited By ~ 6

Author(s):

Xin-Yi Shen ◽

Aubie Angel

Keyword(s):

High Density Lipoprotein ◽

Plasma Membranes ◽

Binding Proteins ◽

Density Lipoprotein ◽

High Density ◽

Rat Adipocytes ◽

Apolipoprotein A ◽

Molecular Masses ◽

Lipoprotein Binding ◽

Adipocyte Plasma Membranes

High density lipoprotein (HDL) binding proteins were identified in nonreduced detergent extracts of plasma membranes or crude membrane fractions of rat adipocytes by ligand blotting. Using 125I-labelled human apolipoprotein-E-free HDL ([125I]HDL3), two binding proteins in adipocyte membranes were detected with apparent molecular masses of 122 and 88 kilodaltons (kDa), respectively. The binding of HDL3 to both binding proteins was abolished by pronase treatment and was inhibited by excess unlabelled HDL3. Excessive unlabelled low density lipoprotein reduced the binding of [125I]HDL3 to the 122-kDa binding protein relatively less than that to the 88-kDa binding protein. Polyclonal antisera against purified rat apolipoprotein A-I (apoA-I) effectively inhibited the binding of HDL3 to adipocyte membranes. Affinity-purified antibodies against rat apoA-I also revealed two HDL-binding proteins in rat adipocyte and liver plasma membranes preincubated with rat HDL. The sizes of the HDL-binding proteins in adipocyte plasma membranes detected by anti-apoA-I were similar to those detected by radiolabelled ligand blotting and their counterparts in rat liver plasma membranes. The study demonstrates two HDL-binding proteins, distinguishable by apparent molecular masses and ligand binding affinity, in plasma membrane proteins of mature rat adipocytes using radiolabelled ligand and immunoligand blotting techniques. The results suggest that apoA-I is involved in the interactions between HDL and both variants of HDL-binding proteins.Key words: high density lipoprotein binding proteins, rat adipocytes, apolipoprotein A-I.

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