The heterotrimeric G protein G(i3) regulates hepatic autophagy downstream
of the insulin receptor
Autophagy, 3 (4):
393-5 (July 2007)Gohla, Antje Klement, Karinna Nurnberg, Bernd Comment Research Support,
Non-U.S. Gov't United States Autophagy Autophagy. 2007 Jul-Aug;3(4):393-5.
Epub 2007 Jul 10..Abstract
Compelling evidence suggests that the heterotrimeric G protein G(i3)
specifically transmits the antiautophagic effects of insulin and
amino acids in the liver. This points to a previously unrecognized
cross talk between the insulin receptor tyrosine kinase and G(i3).
Interestingly, G(i3) is localized not only to plasma membranes but
also to membranes of the autophagosomal compartment. Furthermore,
as part of insulin's or phenylalanine's actions to inhibit autophagy,
G(i3) is redistributed away from autophagosomes. Therefore, endomembrane-associated
rather than plasma membrane-localized G(i3) may serve as the target
of insulin's endocrine and metabolic actions. We therefore propose
that the function and regulation of organelle-associated heterotrimeric
G proteins may be different from their roles at the plasma membrane
where they act as signal transducers of seven-transmembrane receptors.
Here, we discuss recent findings and propose a function for G(i3)
in mTOR-dependent signaling pathways. We hypothesize that G(i) family
members may have tissue-specific roles in the regulation of autophagy
under different physiological and pathological conditions.