title: Regulation of myosin IIA and filamentous actin during insulin-stimulated glucose uptake in 3T3-L1 adipocytes.
abstract: Insulin stimulated glucose uptake requires the colocalization of myosin IIA (MyoIIA) and the insulin-responsive glucose transporter 4 (GLUT4) at the plasma membrane for proper GLUT4 fusion. MyoIIA facilitates filamentous actin (F-actin) reorganization in various cell types. In adipocytes F-actin reorganization is required for insulin-stimulated glucose uptake. What is not known is whether MyoIIA interacts with F-actin to regulate insulin-induced GLUT4 fusion at the plasma membrane. To elucidate the relationship between MyoIIA and F-actin, we examined the colocalization of MyoIIA and F-actin at the plasma membrane upon insulin stimulation as well as the regulation of this interaction. Our findings demonstrated that MyoIIA and F-actin colocalized at the site of GLUT4 fusion with the plasma membrane upon insulin stimulation. Furthermore, inhibition of MyoII with blebbistatin impaired F-actin localization at the plasma membrane. Next we examined the regulatory role of calcium in MyoIIA-F-actin colocalization. Reduced calcium or calmodulin levels decreased colocalization of MyoIIA and F-actin at the plasma membrane. While calcium alone can translocate MyoIIA it did not stimulate F-actin accumulation at the plasma membrane. Taken together, we established that while MyoIIA activity is required for F-actin localization at the plasma membrane, it alone is insufficient to localize F-actin to the plasma membrane.
authors.affiliation: Department of Biology, University of North Carolina at Greensboro, 312 Eberhart Building, Greensboro, NC 27412, USA.
authors.forename: Richard
authors.initials: R
authors.lastname: Stall
authors.affiliation: Department of Biology, University of North Carolina at Greensboro, 312 Eberhart Building, Greensboro, NC 27412, USA.
authors.forename: Joseph
authors.initials: J
authors.lastname: Ramos
authors.affiliation: Department of Biology, University of North Carolina at Greensboro, 312 Eberhart Building, Greensboro, NC 27412, USA.
authors.forename: F
authors.initials: F
authors.lastname: Kent Fulcher
authors.affiliation: Department of Biology, University of North Carolina at Greensboro, 312 Eberhart Building, Greensboro, NC 27412, USA. Electronic address: ympatel@uncg.edu.
authors.forename: Yashomati M
authors.initials: YM
authors.lastname: Patel
mesh_terms: D041721:3T3-L1 Cells; D008841:Actin Cytoskeleton / Q000378:metabolism*; D000199:Actins / Q000378:metabolism; D017667:Adipocytes / Q000187:drug effects* / Q000378:metabolism*; D000818:Animals; D002147:Calmodulin / Q000502:physiology; D002462:Cell Membrane / Q000378:metabolism; D005947:Glucose / Q000493:pharmacokinetics*; D051275:Glucose Transporter Type 4 / Q000378:metabolism; D007328:Insulin / Q000494:pharmacology*; D051379:Mice; D024507:Nonmuscle Myosin Type IIA / Q000378:metabolism*
chemical_list: D000199:Actins; D002147:Calmodulin; D051275:Glucose Transporter Type 4; D007328:Insulin; C495693:Slc2a4 protein, mouse; D024507:Nonmuscle Myosin Type IIA; D005947:Glucose
keywords: Adipocytes; Calcium; Filamentous actin (F-actin); Insulin-responsive glucose transporter (GLUT4); Myosin IIA