scholarly journals Complexin-2 redistributes to the membrane of muscle cells in response to insulin and contributes to GLUT4 translocation

2021 ◽  
Author(s):  
Martin Alejandro Pavarotti ◽  
Victoria Tokarz ◽  
Scott Frendo-Cumbo ◽  
Philip Bilan ◽  
Zhi Liu ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Insulin Signalling ◽  
Muscle Cells ◽  
Secretory Vesicle ◽  
Vesicle Fusion ◽  
Glut4 Translocation ◽  
Vesicle Membrane ◽  
Actin Fiber ◽  
Complexin 2 ◽  
Intracellular Compartments

Insulin stimulates glucose uptake in muscle cells by rapidly redistributing vesicles containing GLUT4 glucose transporters from intracellular compartments to the plasma membrane. GLUT4 vesicle fusion requires formation of SNARE complexes between vesicular VAMP and plasma membrane syntaxin4 and SNAP23. SNARE accessory proteins usually regulate vesicle fusion processes. Complexins aide in neuro-secretory vesicle-membrane fusion by stabilizing trans-SNARE complexes but their participation in GLUT4 vesicle fusion is unknown. We report that complexin-2 is expressed and homogeneously distributed in L6 rat skeletal muscle cells. Upon insulin stimulation, a cohort of complexin-2 redistributes to the plasma membrane. Complexin-2 knockdown markedly inhibited GLUT4 translocation without affecting proximal insulin signalling of Akt/PKB phosphorylation and actin fiber remodelling. Similarly, complexin-2 overexpression decreased maximal GLUT4 translocation suggesting that the concentration of complexin-2 is finely tuned to vesicle fusion.  These findings reveal an insulin-dependent regulation of GLUT4 insertion into the plasma membrane involving complexin-2.

Rab10 in insulin-stimulated GLUT4 translocation

2008 ◽  
Vol 411 (1) ◽  
pp. 89-95 ◽  
Author(s):  
Hiroyuki Sano ◽  
William G. Roach ◽  
Grantley R. Peck ◽  
Mitsunori Fukuda ◽  
Gustav E. Lienhard
Keyword(s):  
Plasma Membrane ◽  
Protein Kinase ◽  
Subcellular Distribution ◽  
Protein Kinase B ◽  
Muscle Cells ◽  
Low Density ◽  
Glut4 Translocation ◽  
Gtpase Activating Protein ◽  
Intracellular Vesicles

In fat and muscle cells, insulin stimulates the movement to and fusion of intracellular vesicles containing GLUT4 with the plasma membrane, a process referred to as GLUT4 translocation. Previous studies have indicated that Akt [also known as PKB (protein kinase B)] phosphorylation of AS160, a GAP (GTPase-activating protein) for Rabs, is required for GLUT4 translocation. The results suggest that this phosphorylation suppresses the GAP activity and leads to the elevation of the GTP form of one or more Rabs required for GLUT4 translocation. Based on their presence in GLUT4 vesicles and activity as AS160 GAP substrates, Rabs 8A, 8B, 10 and 14 are candidate Rabs. Here, we provide further evidence that Rab10 participates in GLUT4 translocation in 3T3-L1 adipocytes. Among Rabs 8A, 8B, 10 and 14, only the knockdown of Rab10 inhibited GLUT4 translocation. In addition, we describe the subcellular distribution of Rab10 and estimate the fraction of Rab10 in the active GTP form in vivo. Approx. 5% of the total Rab10 was present in GLUT4 vesicles isolated from the low-density microsomes. In both the basal and the insulin state, 90% of the total Rab10 was in the inactive GDP state. Thus, if insulin increases the GTP form of Rab10, the increase is limited to a small portion of the total Rab10. Finally, we report that the Rab10 mutant considered to be constitutively active (Rab10 Q68L) is a substrate for the AS160 GAP domain and, hence, cannot be used to deduce rigorously the function of Rab10 in its GTP form.

scholarly journals Akt Activation Is Required at a Late Stage of Insulin-Induced GLUT4 Translocation to the Plasma Membrane

2005 ◽  
Vol 19 (4) ◽  
pp. 1067-1077 ◽  
Author(s):  
Ellen M. van Dam ◽  
Roland Govers ◽  
David E. James
Keyword(s):  
Plasma Membrane ◽  
Glucose Transporter ◽  
Cell Cortex ◽  
Glut4 Translocation ◽  
Akt Activation ◽  
Multistep Process ◽  
Intracellular Compartments ◽  
Insulin Dependent ◽  
Glucose Transporter Glut4 ◽  
Golgi Network

Abstract Insulin stimulates the translocation of glucose transporter GLUT4 from intracellular vesicles to the plasma membrane (PM). This involves multiple steps as well as multiple intracellular compartments. The Ser/Thr kinase Akt has been implicated in this process, but its precise role is ill defined. To begin to dissect the role of Akt in these different steps, we employed a low-temperature block. Upon incubation of 3T3-L1 adipocytes at 19 C, GLUT4 accumulated in small peripheral vesicles with a slight increase in PM labeling concomitant with reduced trans-Golgi network labeling. Although insulin-dependent translocation of GLUT4 to the PM was impaired at 19 C, we still observed movement of vesicles toward the surface. Strikingly, insulin-stimulated Akt activity, but not phosphatidylinositol 3 kinase activity, was blocked at 19 C. Consistent with a multistep process in GLUT4 trafficking, insulin-stimulated GLUT4 translocation could be primed by treating cells with insulin at 19 C, whereas this was not the case for Akt activation. These data implicate two insulin-regulated steps in GLUT4 translocation: 1) redistribution of GLUT4 vesicles toward the cell cortex—this process is Akt-independent and is not blocked at 19 C; and 2) docking and/or fusion of GLUT4 vesicles with the PM—this process may be the major Akt-dependent step in the insulin regulation of glucose transport.

scholarly journals Teucrium polium extracts stimulate GLUT4 translocation to the plasma membrane in L6 muscle cells

2018 ◽  
Vol 6 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Sleman Kadan ◽  
◽  
Yoel Sasson ◽  
Raed Abu-Reziq ◽  
Bashar Saad ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Muscle Cells ◽  
Glut4 Translocation ◽  
Teucrium Polium ◽  
L6 Muscle Cells

Morphometric analysis of ultrastructural changes induced by Periconia circinata toxin in the outer root cap of sorghum

1983 ◽  
Vol 61 (5) ◽  
pp. 1506-1509
Author(s):  
Jonathan A. Arias ◽  
Larry D. Dunkle ◽  
Charles E. Bracker
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Morphometric Analysis ◽  
Secretory Vesicle ◽  
Root Cap ◽  
Toxic Effects ◽  
Ultrastructural Changes ◽  
Vesicle Membrane ◽  
Periconia Circinata ◽  
Resistant Genotypes

Outer root cap cells of sorghum seedlings treated with the host-specific toxin produced by Periconia circinata were analyzed morphometrically to detect changes in the quantities of cytomembranes and numbers of organelles and thus extend our observations of qualitative cytological responses to the toxin. In seedlings susceptible to the pathogen, brief (0.25 h) treatment with the toxin resulted in a marked and permanent decrease in the amounts of secretory vesicle membrane. By 2 h treatment, only secretory vesicle membrane was decreased, but longer treatments led to an increased amount of endoplasmic reticulum (4 h), which later decreased together with the amount of dictyosome membrane, while the amount of tonoplast increased (8 h). In resistant seedlings treated with the toxin, early but transient increases were detected in the quantities of plasma membrane, secretory vesicle membrane, dictyosome membrane, and endoplasmic reticulum and in the number of dictyosomes. Insensitivity to the toxin may involve the ability of resistant genotypes to recover from the toxic effects.

scholarly journals EVIDENCE FOR RECYCLING OF SYNAPTIC VESICLE MEMBRANE DURING TRANSMITTER RELEASE AT THE FROG NEUROMUSCULAR JUNCTION

1973 ◽  
Vol 57 (2) ◽  
pp. 315-344 ◽  
Author(s):  
J. E. Heuser ◽  
T. S. Reese
Keyword(s):  
Plasma Membrane ◽  
Synaptic Vesicle ◽  
Synaptic Vesicles ◽  
Motor Nerve ◽  
Coated Vesicles ◽  
Synaptic Membrane ◽  
Nerve Terminals ◽  
Frog Neuromuscular Junction ◽  
Vesicle Membrane ◽  
Intracellular Compartments

When the nerves of isolated frog sartorius muscles were stimulated at 10 Hz, synaptic vesicles in the motor nerve terminals became transiently depleted. This depletion apparently resulted from a redistribution rather than disappearance of synaptic vesicle membrane, since the total amount of membrane comprising these nerve terminals remained constant during stimulation. At 1 min of stimulation, the 30% depletion in synaptic vesicle membrane was nearly balanced by an increase in plasma membrane, suggesting that vesicle membrane rapidly moved to the surface as it might if vesicles released their content of transmitter by exocytosis. After 15 min of stimulation, the 60% depletion of synaptic vesicle membrane was largely balanced by the appearance of numerous irregular membrane-walled cisternae inside the terminals, suggesting that vesicle membrane was retrieved from the surface as cisternae. When muscles were rested after 15 min of stimulation, cisternae disappeared and synaptic vesicles reappeared, suggesting that cisternae divided to form new synaptic vesicles so that the original vesicle membrane was now recycled into new synaptic vesicles. When muscles were soaked in horseradish peroxidase (HRP), this tracerfirst entered the cisternae which formed during stimulation and then entered a large proportion of the synaptic vesicles which reappeared during rest, strengthening the idea that synaptic vesicle membrane added to the surface was retrieved as cisternae which subsequently divided to form new vesicles. When muscles containing HRP in synaptic vesicles were washed to remove extracellular HRP and restimulated, HRP disappeared from vesicles without appearing in the new cisternae formed during the second stimulation, confirming that a one-way recycling of synaptic membrane, from the surface through cisternae to new vesicles, was occurring. Coated vesicles apparently represented the actual mechanism for retrieval of synaptic vesicle membrane from the plasma membrane, because during nerve stimulation they proliferated at regions of the nerve terminals covered by Schwann processes, took up peroxidase, and appeared in various stages of coalescence with cisternae. In contrast, synaptic vesicles did not appear to return directly from the surface to form cisternae, and cisternae themselves never appeared directly connected to the surface. Thus, during stimulation the intracellular compartments of this synapse change shape and take up extracellular protein in a manner which indicates that synaptic vesicle membrane added to the surface during exocytosis is retrieved by coated vesicles and recycled into new synaptic vesicles by way of intermediate cisternae.

Nibbling at Membranes

2013 ◽  
Vol 21 (5) ◽  
pp. 8-10
Author(s):  
Stephen W. Carmichael
Keyword(s):  
Plasma Membrane ◽  
Spatial Localization ◽  
Secretory Vesicle ◽  
Secretory Cells ◽  
Vesicle Membrane ◽  
Major Pathway ◽  
Vesicle Membranes ◽  
Strong Stimulation ◽  
Sudden Appearance ◽  
The Relationship

It has been known for decades that clathrin- and dynamin-mediated endocytosis is the major pathway for recycling the components of vesicle membranes after strong stimulation and high rates of exocytosis in secretory cells. This pathway occurs over tens of seconds to minutes after fusion of the secretory vesicle membrane with the plasma membrane. It resembles classical receptor-mediated endocytosis, but it has a trigger that is unique to secretion: the sudden appearance of the secretory vesicle membrane on the surface of the cell. However, the spatial localization, the relationship to individual fusion events, the nature of the cargo, and the timing and nature of nucleation events have been unknown. An elegant study by Mary Bittner, Rachel Aikman, and Ronald Holz has addressed these issues.

scholarly journals Secretory Vesicles Targeted to Plasma Membrane During Pollen Germination and Tube Growth

2021 ◽  
Vol 8 ◽  
Author(s):  
Huaqiang Ruan ◽  
Jiang Li ◽  
Ting Wang ◽  
Haiyun Ren
Keyword(s):  
Plasma Membrane ◽  
Pollen Tube ◽  
Pollen Germination ◽  
Higher Plants ◽  
Current Knowledge ◽  
Secretory Vesicle ◽  
Signaling Molecules ◽  
Tube Growth ◽  
Secretory Vesicles ◽  
Vesicle Membrane

Pollen germination and pollen tube growth are important biological events in the sexual reproduction of higher plants, during which a large number of vesicle trafficking and membrane fusion events occur. When secretory vesicles are transported via the F-actin network in proximity to the apex of the pollen tube, the secretory vesicles are tethered and fused to the plasma membrane by tethering factors and SNARE proteins, respectively. The coupling and uncoupling between the vesicle membrane and plasma membrane are also regulated by dynamic cytoskeleton, proteins, and signaling molecules, including small G proteins, calcium, and PIP2. In this review, we focus on the current knowledge regarding secretory vesicle delivery, tethering, and fusion during pollen germination and tube growth and summarize the progress in research on how regulators and signaling molecules participate in the above processes.

scholarly journals Inhibition of insulin-stimulated phosphorylation of the intracellular domain of phospholemman decreases insulin-dependent GLUT4 translocation in streptolysin-O-permeabilized adipocytes

1999 ◽  
Vol 343 (1) ◽  
pp. 151-157 ◽  
Author(s):  
Otto WALAAS ◽  
Robert S. HORN ◽  
S. Ivar WALAAS
Keyword(s):  
Plasma Membrane ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Glucose Transporter ◽  
Insulin Signalling ◽  
Glut4 Translocation ◽  
Intracellular Domain ◽  
Kinase C ◽  
Streptolysin O

A variety of studies indicate that protein kinase C might be involved in the insulin signalling cascade leading to translocation of the insulin-regulated glucose transporter GLUT4 from intracellular pools to the plasma membrane. Phospholemman is a plasma-membrane protein kinase C substrate whose phosphorylation is increased by insulin in intact muscle [Walaas, Czernik, Olstad, Sletten and Walaas (1994) Biochem. J. 304, 635-640]. The present study examined whether the inhibition of phospholemman phosphorylation modulates the effects of insulin on GLUT4 translocation. For this purpose, a synthetic peptide derived from the intracellular domain of phospholemman with the phosphorylatable serine residues replaced with alanine residues was prepared. This peptide was found to decrease the protein kinase C-catalysed phosphorylation of a synthetic phospholemman peptide in vitro. When introduced into streptolysin-O-permeabilized adipocytes, the peptide decreased the effects of insulin on both the phosphorylation of phospholemman and the recruitment of GLUT4 to the plasma membrane. Similarly, the internalization of phospholemman antibodies, which also decreased the protein kinase C-mediated phosphorylation of the synthetic phospholemman peptide in vitro, decreased the effect of insulin on GLUT4 translocation in the adipocytes. The results suggest that phosphorylation of the intracellular domain of phospholemman might be involved in modulating the insulin-induced translocation of GLUT4 to the plasma membrane.

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