Török, Dóra and Patel, N. and Jebailey, L. and Thong, F. S. and Randhawa, V. K. (2004) Insulin but not PDGF relies on actin remodeling and on VAMP2 for GLUT4 translocation in myoblasts. JOURNAL OF CELL SCIENCE, 117 (Pt 22). pp. 5447-5455. ISSN 0021-9533
|
Text
5447.full.pdf Download (484kB) | Preview |
Abstract
Insulin promotes the translocation of glucose transporter 4 (GLUT4) from intracellular pools to the surface of muscle and fat cells via a mechanism dependent on phosphatidylinositol (PtdIns) 3-kinase, actin cytoskeletal remodeling and the v-SNARE VAMP2. The growth factor PDGF-BB also robustly activates PtdIns 3-kinase and induces actin remodeling, raising the question of whether it uses similar mechanisms to insulin in mobilizing GLUT4. In L6 myoblasts stably expressing Myc-tagged GLUT4, neither stimulus affected the rate of GLUT4 endocytosis, confirming that they act primarily by enhancing exocytosis to increase GLUT4 at the cell surface. Although surface GLUT4myc in response to insulin peaked at 10 minutes and remained steady for 30 minutes, PDGF action was transient, peaking at 5 minutes and disappearing by 20 minutes. These GLUT4myc translocation time courses mirrored that of phosphorylation of Akt by the two stimuli. Interestingly, insulin and PDGF caused distinct manifestations of actin remodeling. Insulin induced discrete, long (>5 microm) dorsal actin structures at the cell periphery, whereas PDGF induced multiple short (<5 microm) dorsal structures throughout the cell, including above the nucleus. Latrunculin B, cytochalasin D and jasplakinolide, which disrupt actin dynamics, prevented insulin- and PDGF-induced actin remodeling but significantly inhibited GLUT4myc translocation only in response to insulin (75-85%, P<0.05), not to PDGF (20-30% inhibition). Moreover, transfection of tetanus toxin light chain, which cleaves the v-SNAREs VAMP2 and VAMP3, reduced insulin-induced GLUT4myc translocation by >70% but did not affect the PDGF response. These results suggest that insulin and PDGF rely differently on the actin cytoskeleton and on tetanus-toxin-sensitive VAMPs for mobilizing GLUT4.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | Vesicle-Associated Membrane Protein 3; Transfection; Time Factors; Tetanus Toxin/pharmacology; RATS; R-SNARE Proteins; Proto-Oncogene Proteins c-akt; Proto-Oncogene Proteins/metabolism; Protein-Serine-Threonine Kinases/metabolism; Protein Transport; Platelet-Derived Growth Factor/*metabolism; Phosphatidylinositol 3-Kinases/metabolism; Muscles/metabolism; Muscle Proteins/*metabolism; Monosaccharide Transport Proteins/*metabolism; Microscopy, Fluorescence; Membrane Proteins/metabolism; Insulin Resistance; Insulin/*metabolism; immunoblotting; Glucose Transporter Type 4; Glucose/metabolism; Exocytosis; Cytoskeleton/metabolism; Cell Line; Animals; Actins/chemistry/*metabolism |
| Subjects: | R Medicine / orvostudomány > R1 Medicine (General) / orvostudomány általában |
| SWORD Depositor: | MTMT SWORD |
| Depositing User: | MTMT SWORD |
| Date Deposited: | 31 Mar 2017 12:13 |
| Last Modified: | 31 Mar 2017 12:13 |
| URI: | http://real.mtak.hu/id/eprint/50804 |
Actions (login required)
 |
Edit Item |
