Post-translational regulation of the glucose-6-phosphatase complex by cyclic adenosine monophosphate is a crucial determinant of endogenous glucose production and is controlled by the glucose-6-phosphate transporter
File(s)
Accepted version
Author(s)
Type
Journal Article
Abstract
The excessive endogenous glucose production (EGP) induced by glucagon participates in the development of type 2 diabetes. To further understand this hormonal control, we studied the short-term regulation by cyclic adenosine monophosphate (cAMP) of the glucose-6-phosphatase (G6Pase) enzyme, which catalyzes the last reaction of EGP. In gluconeogenic cell models, a 1-h treatment by the adenylate cyclase activator forskolin increased G6Pase activity and glucose production independently of any change in enzyme protein amount or G6P content. Using specific inhibitors or protein overexpression, we showed that the stimulation of G6Pase activity involved the protein kinase A (PKA). Results of site-directed mutagenesis, mass spectrometry analyses, and in vitro phosphorylation experiments suggested that the PKA stimulation of G6Pase activity did not depend on a direct phosphorylation of the enzyme. However, the temperature-dependent induction of both G6Pase activity and glucose release suggested a membrane-based mechanism. G6Pase is composed of a G6P transporter (G6PT) and a catalytic unit (G6PC). Surprisingly, we demonstrated that the increase in G6PT activity was required for the stimulation of G6Pase activity by forskolin. Our data demonstrate the existence of a post-translational mechanism that regulates G6Pase activity and reveal the key role of G6PT in the hormonal regulation of G6Pase activity and of EGP.
Date Issued
2016-04-01
Date Acceptance
2016-03-01
Citation
Journal of Proteome Research, 2016, 15 (4), pp.1342-1349
ISSN
1535-3907
Publisher
American Chemical Society
Start Page
1342
End Page
1349
Journal / Book Title
Journal of Proteome Research
Volume
15
Issue
4
Copyright Statement
This document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of Proteome Research © 2016 American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://dx.doi.org/10.1021/acs.jproteome.6b00110
Subjects
Type 2 diabetes
glucagon
gluconeogenesis
glucose-6-phosphatase
glucose-6-phosphate transporter
post-translational modification (PTM)
protein kinase A
Biochemistry & Molecular Biology
Biological Sciences
Chemical Sciences
Publication Status
Published