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ARFGAP1 is dynamically associated with lipid droplets in hepatocytes.

Gannon J, Fernandez-Rodriguez J, Alamri H, Feng SB, Kalantari F, Negi S, Wong AH, Mazur A, Asp L, Fazel A, Salman A, Lazaris A, Metrakos P, Bergeron JJ, Nilsson T - PLoS ONE (2014)

Bottom Line: In this study, we show that ARFGAP1 associates transiently with lipid droplets upon addition of oleate in cultured cells.Also, that addition of cyclic AMP shifts ARFGAP1 from lipid droplets to the Golgi apparatus and that overexpression and knockdown of ARFGAP1 affect lipid droplet formation.Examination of human liver tissue reveals that ARFGAP1 is found associated with lipid droplets at steady state in some but not all hepatocytes.

View Article: PubMed Central - PubMed

Affiliation: The Research Institute of the McGill University Health Centre, McGill, Royal Victoria Hospital, 687 Pine Avenue West, Montreal, Quebec, Canada.

ABSTRACT
The ARF GTPase Activating Protein 1 (ARFGAP1) associates mainly with the cytosolic side of Golgi cisternal membranes where it participates in the formation of both COPI and clathrin-coated vesicles. In this study, we show that ARFGAP1 associates transiently with lipid droplets upon addition of oleate in cultured cells. Also, that addition of cyclic AMP shifts ARFGAP1 from lipid droplets to the Golgi apparatus and that overexpression and knockdown of ARFGAP1 affect lipid droplet formation. Examination of human liver tissue reveals that ARFGAP1 is found associated with lipid droplets at steady state in some but not all hepatocytes.

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Related in: MedlinePlus

Cyclic AMP reverses lipid droplet association of ARFGAP1.McA-RH7777 cells were incubated with 0.5 mM oleate for 4 hours after which cyclic AMP (cAMP) was added to a final concentration of 37.5µg/ml. The cells were simultaneously stained for endogenous ARFGAP1 (red) and neutral lipid with Bodipy 493/503 (green). Bars  = 5µm.
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pone-0111309-g009: Cyclic AMP reverses lipid droplet association of ARFGAP1.McA-RH7777 cells were incubated with 0.5 mM oleate for 4 hours after which cyclic AMP (cAMP) was added to a final concentration of 37.5µg/ml. The cells were simultaneously stained for endogenous ARFGAP1 (red) and neutral lipid with Bodipy 493/503 (green). Bars  = 5µm.

Mentions: Based on above data, it appears that most if not all ARFGAP1 associates transiently with lipid droplets peaking at 4 hours after addition of oleate. Such transient association suggests a dynamic recruitment of ARFGAP1 to lipid droplets upon oleate uptake, possibly regulated by cAMP effector proteins such as cAMP-dependent protein kinase (PKA) shown to affect lipid homeostasis [35]. To test this, McA-RH7777 cells were incubated in the presence of oleate for 4 hours (Fig. 9) followed by addition of cAMP. Before addition of cAMP, most if not all of endogenous ARFGAP1 localized to peri-lipid droplet structures positive for Bodipy (Fig. 9 upper panels). As above, no discernable juxta nuclear Golgi staining was observed. At 10 minutes after cAMP addition, staining for endogenous ARFGAP1 was detected in the juxta nuclear Golgi region as well as around lipid droplet structures (Fig. 9-middle panels). At 30 minutes after cAMP addition, staining for endogenous ARFGAP1 was mainly detected in the juxta nuclear Golgi apparatus with some staining remaining around lipid droplet structures. At these time points (10 and 30 minutes), no discernable decrease in the overall amount of lipid droplets was observed (Fig. 9).


ARFGAP1 is dynamically associated with lipid droplets in hepatocytes.

Gannon J, Fernandez-Rodriguez J, Alamri H, Feng SB, Kalantari F, Negi S, Wong AH, Mazur A, Asp L, Fazel A, Salman A, Lazaris A, Metrakos P, Bergeron JJ, Nilsson T - PLoS ONE (2014)

Cyclic AMP reverses lipid droplet association of ARFGAP1.McA-RH7777 cells were incubated with 0.5 mM oleate for 4 hours after which cyclic AMP (cAMP) was added to a final concentration of 37.5µg/ml. The cells were simultaneously stained for endogenous ARFGAP1 (red) and neutral lipid with Bodipy 493/503 (green). Bars  = 5µm.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4232254&req=5

pone-0111309-g009: Cyclic AMP reverses lipid droplet association of ARFGAP1.McA-RH7777 cells were incubated with 0.5 mM oleate for 4 hours after which cyclic AMP (cAMP) was added to a final concentration of 37.5µg/ml. The cells were simultaneously stained for endogenous ARFGAP1 (red) and neutral lipid with Bodipy 493/503 (green). Bars  = 5µm.
Mentions: Based on above data, it appears that most if not all ARFGAP1 associates transiently with lipid droplets peaking at 4 hours after addition of oleate. Such transient association suggests a dynamic recruitment of ARFGAP1 to lipid droplets upon oleate uptake, possibly regulated by cAMP effector proteins such as cAMP-dependent protein kinase (PKA) shown to affect lipid homeostasis [35]. To test this, McA-RH7777 cells were incubated in the presence of oleate for 4 hours (Fig. 9) followed by addition of cAMP. Before addition of cAMP, most if not all of endogenous ARFGAP1 localized to peri-lipid droplet structures positive for Bodipy (Fig. 9 upper panels). As above, no discernable juxta nuclear Golgi staining was observed. At 10 minutes after cAMP addition, staining for endogenous ARFGAP1 was detected in the juxta nuclear Golgi region as well as around lipid droplet structures (Fig. 9-middle panels). At 30 minutes after cAMP addition, staining for endogenous ARFGAP1 was mainly detected in the juxta nuclear Golgi apparatus with some staining remaining around lipid droplet structures. At these time points (10 and 30 minutes), no discernable decrease in the overall amount of lipid droplets was observed (Fig. 9).

Bottom Line: In this study, we show that ARFGAP1 associates transiently with lipid droplets upon addition of oleate in cultured cells.Also, that addition of cyclic AMP shifts ARFGAP1 from lipid droplets to the Golgi apparatus and that overexpression and knockdown of ARFGAP1 affect lipid droplet formation.Examination of human liver tissue reveals that ARFGAP1 is found associated with lipid droplets at steady state in some but not all hepatocytes.

View Article: PubMed Central - PubMed

Affiliation: The Research Institute of the McGill University Health Centre, McGill, Royal Victoria Hospital, 687 Pine Avenue West, Montreal, Quebec, Canada.

ABSTRACT
The ARF GTPase Activating Protein 1 (ARFGAP1) associates mainly with the cytosolic side of Golgi cisternal membranes where it participates in the formation of both COPI and clathrin-coated vesicles. In this study, we show that ARFGAP1 associates transiently with lipid droplets upon addition of oleate in cultured cells. Also, that addition of cyclic AMP shifts ARFGAP1 from lipid droplets to the Golgi apparatus and that overexpression and knockdown of ARFGAP1 affect lipid droplet formation. Examination of human liver tissue reveals that ARFGAP1 is found associated with lipid droplets at steady state in some but not all hepatocytes.

Show MeSH
Related in: MedlinePlus