Article

AMP-activated protein kinase phosphorylates Golgi-specific brefeldin A resistance factor 1 at Thr1337 to induce disassembly of Golgi apparatus.

Biosignal Research Center, Kobe University, Kobe 657-8501, Japan.
Journal of Biological Chemistry (impact factor: 4.77). 03/2008; 283(7):4430-8. DOI:10.1074/jbc.M708296200 pp.4430-8
Source: PubMed

ABSTRACT Sufficiency and depletion of nutrients regulate the cellular activities through the protein phosphorylation reaction; however, many protein substrates remain to be clarified. GBF1 (Golgi-specific brefeldin A resistance factor 1), a guanine nucleotide exchange factor for the ADP-ribosylation factor family associated with the Golgi apparatus, was isolated as a phosphoprotein from the glucose-depleted cells by using the phospho-Akt-substrate antibody, which recognizes the substrate proteins of several protein kinases. The phosphorylation of GBF1 was induced by 2-deoxyglucose (2-DG), which blocks glucose utilization and increases the intracellular AMP concentration, and by AICAR, an AMP-activated protein kinase (AMPK) activator. This phosphorylation was observed in the cells expressing the constitutively active AMPK. The 2-DG-induced phosphorylation of GBF1 was suppressed by Compound C, an AMPK inhibitor, and by the overexpression of the kinase-negative AMPK. Analysis using the deletion and point mutants identified Thr(1337) as the 2-DG-induced phosphorylation site in GBF1, which is phosphorylated by AMPK in vitro. ATP depletion is known to provoke the Golgi apparatus disassembly. Immunofluorescent microscopic analysis with the Golgi markers indicated that GBF1 associates with the fragmented Golgi apparatus in the cells treated with 2-DG and AICAR. The expression of the kinase-negative AMPK and the GBF1 mutant replacing Thr(1337) by Ala prevented the 2-DG-induced Golgi disassembly. These results indicate that GBF1 is a novel AMPK substrate and that the AMPK-mediated phosphorylation of GBF1 at Thr(1337) has a critical role, presumably by attenuating the function of GBF1, in the disassembly of the Golgi apparatus induced under stress conditions that lower the intracellular ATP concentration.

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    [show abstract] [hide abstract]
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    BMC Biochemistry 11/2011; 12:57. · 1.99 Impact Factor
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Keywords

2-DG-induced Golgi disassembly
 
2-DG-induced phosphorylation
 
2-DG-induced phosphorylation site
 
ADP-ribosylation factor family
 
AMP-activated protein kinase
 
AMPK-mediated phosphorylation
 
blocks glucose utilization
 
Compound C
 
constitutively active AMPK
 
critical role
 
GBF1 associates
 
GBF1 mutant
 
Golgi apparatus induced
 
Immunofluorescent microscopic analysis
 
intracellular AMP concentration
 
intracellular ATP concentration
 
kinase-negative AMPK
 
novel AMPK substrate
 
protein phosphorylation reaction
 
resistance factor 1