TY - JOUR
T1 - Functional analysis of long-chain Acyl-CoA synthetase 1 in 3T3-L1 adipocytes
AU - Lobo, Sandra
AU - Wiczer, Brian M.
AU - Bernlohr, David A.
PY - 2009/7/3
Y1 - 2009/7/3
N2 - ACSL1 (acyl-CoA synthetase 1), the major acyl-CoA synthetase of adipocytes, has been proposed to function in adipocytes as mediating free fatty acid influx, esterification, and storage as triglyceride. To test this hypothesis, ACSL1 was stably silenced (knockdown (kd))in 3T3-L1 cells, differentiated into adipocytes, and evaluated for changes in lipid metabolism. Surprisingly, ACSL1-silenced adipocytes exhibited no significant changes in basal or insulin-stimulated long-chain fatty acid uptake, lipid droplet size, or tri-, di-, or monoacylglycerol levels when compared with a control adipocyte line. However, ACSL1 kd adipocytes displayed a 7-fold increase in basal and a ∼15% increase in forskolin-stimulated fatty acid efflux without any change in glycerol release, indicating a role for the protein in fatty acid reesterification following lipolysis. Consistent with this proposition, ACSL1 kd cells exhibited a decrease in activation and phosphorylation of AMP-activated protein kinase and its primary substrate acetyl-CoA carboxylase. Moreover, ACSL1 kd adipocytes displayed an increase in phosphorylated protein kinase C0 and phosphorylated JNK, attenuated insulin signaling, and a decrease in insulin-stimulated glucose uptake. These findings identify a primary role of ACSL1 in adipocytes not in control of lipid influx, as previously considered, but in lipid efflux and fatty acid-induced insulin resistance.
AB - ACSL1 (acyl-CoA synthetase 1), the major acyl-CoA synthetase of adipocytes, has been proposed to function in adipocytes as mediating free fatty acid influx, esterification, and storage as triglyceride. To test this hypothesis, ACSL1 was stably silenced (knockdown (kd))in 3T3-L1 cells, differentiated into adipocytes, and evaluated for changes in lipid metabolism. Surprisingly, ACSL1-silenced adipocytes exhibited no significant changes in basal or insulin-stimulated long-chain fatty acid uptake, lipid droplet size, or tri-, di-, or monoacylglycerol levels when compared with a control adipocyte line. However, ACSL1 kd adipocytes displayed a 7-fold increase in basal and a ∼15% increase in forskolin-stimulated fatty acid efflux without any change in glycerol release, indicating a role for the protein in fatty acid reesterification following lipolysis. Consistent with this proposition, ACSL1 kd cells exhibited a decrease in activation and phosphorylation of AMP-activated protein kinase and its primary substrate acetyl-CoA carboxylase. Moreover, ACSL1 kd adipocytes displayed an increase in phosphorylated protein kinase C0 and phosphorylated JNK, attenuated insulin signaling, and a decrease in insulin-stimulated glucose uptake. These findings identify a primary role of ACSL1 in adipocytes not in control of lipid influx, as previously considered, but in lipid efflux and fatty acid-induced insulin resistance.
UR - http://www.scopus.com/inward/record.url?scp=67650526093&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=67650526093&partnerID=8YFLogxK
U2 - 10.1074/jbc.M109.017244
DO - 10.1074/jbc.M109.017244
M3 - Article
C2 - 19429676
AN - SCOPUS:67650526093
SN - 0021-9258
VL - 284
SP - 18347
EP - 18356
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 27
ER -