Myosin IIA participates in docking of Glut4 storage vesicles with the plasma membrane in 3T3-L1 adipocytes.
In adipocytes and myocytes, insulin stimulation translocates glucose transporter 4 (Glut4) storage vesicles (GSVs) from their intracellular storage sites to the plasma membrane (PM) where they dock with the PM. Then, Glut4 is inserted into the PM and initiates glucose uptake into these cells. Previous studies using chemical inhibitors demonstrated that myosin II participates in fusion of GSVs and the PM and increase in the intrinsic activity of Glut4. In this study, the effect of myosin IIA on GSV trafficking was examined by knocking down myosin IIA expression. Myosin IIA knockdown decreased both glucose uptake and exposures of myc-tagged Glut4 to the cell surface in insulin-stimulated cells, but did not affect insulin signal transduction. Interestingly, myosin IIA knockdown failed to decrease insulin-dependent trafficking of Glut4 to the PM. Moreover, in myosin IIA knockdown cells, insulin-stimulated binding of GSV SNARE protein, vesicle-associated membrane protein 2 (VAMP2) to PM SNARE protein, syntaxin 4 was inhibited. These data suggest that myosin IIA plays a role in insulin-stimulated docking of GSVs to the PM in 3T3-L1 adipocytes through SNARE complex formation.
Chung
Le Thi Kim
le TK
Department of Nutrition and Metabolism, Institute of Health Biosciences, The University of Tokushima Graduate School, 3-18-15 Kuramoto-cho, Tokushima 770-8503, Japan. ngocanh@nutr.med.tokushima-u.ac.jp
Hosaka
Toshio
T
Harada
Nagakatsu
N
Jambaldorj
Bayasgalan
B
Fukunaga
Keiko
K
Nishiwaki
Yuka
Y
Teshigawara
Kiyoshi
K
Sakai
Tohru
T
Nakaya
Yutaka
Y
Funaki
Makoto
M
D041721:3T3-L1 Cells; D017667:Adipocytes / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D002462:Cell Membrane / Q000378:metabolism*; D022162:Cytoplasmic Vesicles / Q000378:metabolism; D055785:Gene Knockdown Techniques; D005947:Glucose / Q000378:metabolism / Q000494:pharmacology; D051275:Glucose Transporter Type 4 / Q000378:metabolism*; D007328:Insulin / Q000378:metabolism* / Q000494:pharmacology; D051379:Mice; D024507:Nonmuscle Myosin Type IIA / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport; D050600:SNARE Proteins / Q000378:metabolism; D015398:Signal Transduction; D050988:Vesicle-Associated Membrane Protein 2 / Q000378:metabolism
D051275:Glucose Transporter Type 4; D007328:Insulin; D050600:SNARE Proteins; C495693:Slc2a4 protein, mouse; D050988:Vesicle-Associated Membrane Protein 2; C494808:vesicle-associated membrane protein 2, mouse; D024507:Nonmuscle Myosin Type IIA; D005947:Glucose