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The exocyst complex regulates free fatty acid uptake by adipocytes.

Inoue M, Akama T, Jiang Y, Chun TH - PLoS ONE (2015)

Bottom Line: Gene silencing of the exocyst components Exo70 and Sec8 significantly reduced insulin-dependent FFA uptake by adipocytes.Tubulin polymerization was also found to regulate FFA uptake in collaboration with the exocyst complex.This study demonstrates a novel role played by the exocyst complex in the regulation of FFA uptake by adipocytes.

View Article: PubMed Central - PubMed

Affiliation: Division of Metabolism, Endocrinology & Diabetes (MEND), Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI, United States of America.

ABSTRACT
The exocyst is an octameric molecular complex that drives vesicle trafficking in adipocytes, a rate-limiting step in insulin-dependent glucose uptake. This study assessed the role of the exocyst complex in regulating free fatty acid (FFA) uptake by adipocytes. Upon differentiating into adipocytes, 3T3-L1 cells acquire the ability to incorporate extracellular FFAs in an insulin-dependent manner. A kinetic assay using fluoresceinated FFA (C12 dodecanoic acid) uptake allows the real-time monitoring of FFA internalization by adipocytes. The insulin-dependent uptake of C12 dodecanoic acid by 3T3-L1 adipocytes is mediated by Akt and phosphatidylinositol 3 (PI3)-kinase. Gene silencing of the exocyst components Exo70 and Sec8 significantly reduced insulin-dependent FFA uptake by adipocytes. Consistent with the roles played by Exo70 and Sec8 in FFA uptake, mCherry-tagged Exo70 and HA-tagged Sec8 partially colocalize with lipid droplets within adipocytes, suggesting their active roles in the development of lipid droplets. Tubulin polymerization was also found to regulate FFA uptake in collaboration with the exocyst complex. This study demonstrates a novel role played by the exocyst complex in the regulation of FFA uptake by adipocytes.

No MeSH data available.


Related in: MedlinePlus

The expression and localization of the exocyst complex in adipocytes.(A) The mRNA expression of Exo70, Sec6, and Sec8 before and after 3T3-L1 adipocyte differentiation. Pread: 3T1-L1 preadipocytes, Ad: 3T3-L1 adipocytes. (B) Upper, intracellular localization of mCherry-Exo70 (red) and lipid droplets stained with BODIPY 493/503 (green); lower, HA-Sec8 (red) and lipid droplets (green). Scale = 10 μm.
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pone.0120289.g003: The expression and localization of the exocyst complex in adipocytes.(A) The mRNA expression of Exo70, Sec6, and Sec8 before and after 3T3-L1 adipocyte differentiation. Pread: 3T1-L1 preadipocytes, Ad: 3T3-L1 adipocytes. (B) Upper, intracellular localization of mCherry-Exo70 (red) and lipid droplets stained with BODIPY 493/503 (green); lower, HA-Sec8 (red) and lipid droplets (green). Scale = 10 μm.

Mentions: The exocyst complex plays a major role in the regulation of insulin-dependent glucose uptake [16]. We hypothesized that exocyst-dependent vesicular trafficking may play a role in FFA uptake by adipocytes. When we examined the expression of the exocyst components before and after adipocyte differentiation, we observed the mRNA expressions of Exo70, Sec6, and Sec8 were significantly higher in differentiated adipocytes than in preadipocytes (Fig. 3A).


The exocyst complex regulates free fatty acid uptake by adipocytes.

Inoue M, Akama T, Jiang Y, Chun TH - PLoS ONE (2015)

The expression and localization of the exocyst complex in adipocytes.(A) The mRNA expression of Exo70, Sec6, and Sec8 before and after 3T3-L1 adipocyte differentiation. Pread: 3T1-L1 preadipocytes, Ad: 3T3-L1 adipocytes. (B) Upper, intracellular localization of mCherry-Exo70 (red) and lipid droplets stained with BODIPY 493/503 (green); lower, HA-Sec8 (red) and lipid droplets (green). Scale = 10 μm.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4359155&req=5

pone.0120289.g003: The expression and localization of the exocyst complex in adipocytes.(A) The mRNA expression of Exo70, Sec6, and Sec8 before and after 3T3-L1 adipocyte differentiation. Pread: 3T1-L1 preadipocytes, Ad: 3T3-L1 adipocytes. (B) Upper, intracellular localization of mCherry-Exo70 (red) and lipid droplets stained with BODIPY 493/503 (green); lower, HA-Sec8 (red) and lipid droplets (green). Scale = 10 μm.
Mentions: The exocyst complex plays a major role in the regulation of insulin-dependent glucose uptake [16]. We hypothesized that exocyst-dependent vesicular trafficking may play a role in FFA uptake by adipocytes. When we examined the expression of the exocyst components before and after adipocyte differentiation, we observed the mRNA expressions of Exo70, Sec6, and Sec8 were significantly higher in differentiated adipocytes than in preadipocytes (Fig. 3A).

Bottom Line: Gene silencing of the exocyst components Exo70 and Sec8 significantly reduced insulin-dependent FFA uptake by adipocytes.Tubulin polymerization was also found to regulate FFA uptake in collaboration with the exocyst complex.This study demonstrates a novel role played by the exocyst complex in the regulation of FFA uptake by adipocytes.

View Article: PubMed Central - PubMed

Affiliation: Division of Metabolism, Endocrinology & Diabetes (MEND), Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI, United States of America.

ABSTRACT
The exocyst is an octameric molecular complex that drives vesicle trafficking in adipocytes, a rate-limiting step in insulin-dependent glucose uptake. This study assessed the role of the exocyst complex in regulating free fatty acid (FFA) uptake by adipocytes. Upon differentiating into adipocytes, 3T3-L1 cells acquire the ability to incorporate extracellular FFAs in an insulin-dependent manner. A kinetic assay using fluoresceinated FFA (C12 dodecanoic acid) uptake allows the real-time monitoring of FFA internalization by adipocytes. The insulin-dependent uptake of C12 dodecanoic acid by 3T3-L1 adipocytes is mediated by Akt and phosphatidylinositol 3 (PI3)-kinase. Gene silencing of the exocyst components Exo70 and Sec8 significantly reduced insulin-dependent FFA uptake by adipocytes. Consistent with the roles played by Exo70 and Sec8 in FFA uptake, mCherry-tagged Exo70 and HA-tagged Sec8 partially colocalize with lipid droplets within adipocytes, suggesting their active roles in the development of lipid droplets. Tubulin polymerization was also found to regulate FFA uptake in collaboration with the exocyst complex. This study demonstrates a novel role played by the exocyst complex in the regulation of FFA uptake by adipocytes.

No MeSH data available.


Related in: MedlinePlus