NCS-1 inhibits insulin-stimulated GLUT4 translocation in 3T3L1 adipocytes through a phosphatidylinositol 4-kinase-dependent pathway.
Expression of NCS-1 (neuronal calcium sensor-1, also termed frequenin) in 3T3L1 adipocytes strongly inhibited insulin-stimulated translocation of GLUT4 and insulin-responsive aminopeptidase. The effect of NCS-1 was specific for GLUT4 and the insulin-responsive aminopeptidase translocation as there was no effect on the trafficking of the cation-independent mannose 6-phosphate receptor or the GLUT1 glucose transporter isoform. Moreover, NCS-1 showed partial colocalization with GLUT4-EGFP in the perinuclear region. The inhibitory action of NCS-1 was independent of calcium sequestration since neither treatment with ionomycin nor endothelin-1, both of which elevated the intracellular calcium concentration, restored insulin-stimulated GLUT4 translocation. Furthermore, NCS-1 did not alter the insulin-stimulated protein kinase B (PKB/Akt) phosphorylation or the recruitment of Cbl to the plasma membrane. In contrast, expression of the NCS-1 effector phosphatidylinositol 4-kinase (PI 4-kinase) inhibited insulin-stimulated GLUT4 translocation, whereas co-transfection with an inactive PI 4-kinase mutant prevented the NCS-1-induced inhibition. These data demonstrate that PI 4-kinase functions to negatively regulate GLUT4 translocation through its interaction with NCS-1.
Mora
Silvia
S
Department of Physiology and Biophysics, University of Iowa, 51 Newton Road, Iowa City, IA 52246, USA.
Durham
Paul L
PL
Smith
Jeffery R
JR
Russo
Andrew F
AF
Jeromin
Andreas
A
Pessin
Jeffrey E
JE
D019870:1-Phosphatidylinositol 4-Kinase / Q000378:metabolism*; D016475:3T3 Cells; D017667:Adipocytes / Q000378:metabolism; D000818:Animals; D001692:Biological Transport; D002118:Calcium / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D002454:Cell Differentiation; D002462:Cell Membrane / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D051275:Glucose Transporter Type 4; D051379:Mice; D008856:Microscopy, Fluorescence; D009004:Monosaccharide Transport Proteins / Q000378:metabolism*; D009124:Muscle Proteins; D051580:Neuronal Calcium-Sensor Proteins; D009479:Neuropeptides / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding; D020033:Protein Isoforms; D017346:Protein Serine-Threonine Kinases; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt
D002135:Calcium-Binding Proteins; D018076:DNA, Complementary; D051275:Glucose Transporter Type 4; D009004:Monosaccharide Transport Proteins; D009124:Muscle Proteins; D051580:Neuronal Calcium-Sensor Proteins; D009479:Neuropeptides; D020033:Protein Isoforms; D011518:Proto-Oncogene Proteins; C495693:Slc2a4 protein, mouse; C101464:frequenin calcium sensor proteins; D019870:1-Phosphatidylinositol 4-Kinase; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D002118:Calcium