TY - JOUR
T1 - High basal cell surface levels of fish GLUT4 are related to reduced sensitivity of insulin-induced translocation toward GGA and AS160 inhibition in adipocytes
AU - Capilla, Encarnación
AU - Díaz, Mònica
AU - Hou, June Chunqiu
AU - Planas, Josep V.
AU - Pessin, Jeffrey E.
PY - 2010/2
Y1 - 2010/2
N2 - Glucose entry into cells is mediated by a family of facilitative transporter proteins (GLUTs). In mammals, GLUT4 is expressed in insulin-sensitive tissues and is responsible for the postprandial uptake of glucose. In fish, GLUT4 also mediates insulin-regulated glucose entry into cells but differs from mammalian GLUT4 in its affinity for glucose and in protein motifs known to be important for the traffic of GLUT4. In this study, we have characterized the intracellular and plasma membrane (PM) traffic of two orthologs of GLUT4 in fish, trout (btGLUT4) and salmon (okGLUT4), that do not share the amino terminal FQQI targeting motif of mammalian GLUT4. btGLUT4 (FQHL) and, to a lesser extent, okGLUT4 (FQQL) showed higher basal PM levels, faster traffic to the PM after biosynthesis, and earlier acquisition of insulin responsiveness than rat GLUT4. Furthermore, btGLUT4 showed a similar profile of internalization than rat GLUT4. Expression of the dominant-interfering AS160-4P mutant caused a significant decrease in the insulin-induced PM levels of okGLUT4 and rat GLUT4 and, to a lesser extent, of btGLUT4, suggesting that btGLUT4 has reduced retention into the IRC. Contrary to rat GLUT4 and okGLUT4, the presence of btGLUT4 at the PM under insulin-stimulated conditions was not affected by coexpression of a dominantinterfering GGA mutant. These data suggest that fish GLUT4 follow a different trafficking pathway to the PM compared with rat GLUT4 that seems to be relatively independent of GGA. These results indicate that the regulated trafficking characteristics of GLUT4 have been modified during evolution from fish to mammals.
AB - Glucose entry into cells is mediated by a family of facilitative transporter proteins (GLUTs). In mammals, GLUT4 is expressed in insulin-sensitive tissues and is responsible for the postprandial uptake of glucose. In fish, GLUT4 also mediates insulin-regulated glucose entry into cells but differs from mammalian GLUT4 in its affinity for glucose and in protein motifs known to be important for the traffic of GLUT4. In this study, we have characterized the intracellular and plasma membrane (PM) traffic of two orthologs of GLUT4 in fish, trout (btGLUT4) and salmon (okGLUT4), that do not share the amino terminal FQQI targeting motif of mammalian GLUT4. btGLUT4 (FQHL) and, to a lesser extent, okGLUT4 (FQQL) showed higher basal PM levels, faster traffic to the PM after biosynthesis, and earlier acquisition of insulin responsiveness than rat GLUT4. Furthermore, btGLUT4 showed a similar profile of internalization than rat GLUT4. Expression of the dominant-interfering AS160-4P mutant caused a significant decrease in the insulin-induced PM levels of okGLUT4 and rat GLUT4 and, to a lesser extent, of btGLUT4, suggesting that btGLUT4 has reduced retention into the IRC. Contrary to rat GLUT4 and okGLUT4, the presence of btGLUT4 at the PM under insulin-stimulated conditions was not affected by coexpression of a dominantinterfering GGA mutant. These data suggest that fish GLUT4 follow a different trafficking pathway to the PM compared with rat GLUT4 that seems to be relatively independent of GGA. These results indicate that the regulated trafficking characteristics of GLUT4 have been modified during evolution from fish to mammals.
KW - 3T3-L1 cells
KW - Glucose transport
KW - Glucose transporter 4
KW - Golgi-localized γ-ear-containing Arf-binding protein
KW - Salmon
KW - Trout
UR - http://www.scopus.com/inward/record.url?scp=74949109337&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=74949109337&partnerID=8YFLogxK
U2 - 10.1152/ajpendo.00547.2009
DO - 10.1152/ajpendo.00547.2009
M3 - Article
C2 - 20075431
AN - SCOPUS:74949109337
SN - 0193-1849
VL - 298
SP - E329-E336
JO - American Journal of Physiology - Endocrinology and Metabolism
JF - American Journal of Physiology - Endocrinology and Metabolism
IS - 2
ER -