A conserved role for phosphatidylinositol 3-kinase but not Akt signaling in mitochondrial adaptations that accompany physiological cardiac hypertrophy.
Physiological cardiac hypertrophy is associated with mitochondrial adaptations that are characterized by activation of PGC-1alpha and increased fatty acid oxidative (FAO) capacity. It is widely accepted that phosphatidylinositol 3-kinase (PI3K) signaling to Akt1 is required for physiological cardiac growth. However, the signaling pathways that coordinate physiological hypertrophy and metabolic remodeling are incompletely understood. We show here that activation of PI3K is sufficient to increase myocardial FAO capacity and that inhibition of PI3K signaling prevents mitochondrial adaptations in response to physiological hypertrophic stimuli despite increased expression of PGC-1alpha. We also show that activation of the downstream kinase Akt is not required for the mitochondrial adaptations that are secondary to PI3K activation. Thus, in physiological cardiac growth, PI3K is an integrator of cellular growth and metabolic remodeling. Although PI3K signaling to Akt1 is required for cellular growth, Akt-independent pathways mediate the accompanying mitochondrial adaptations.
O'Neill
Brian T
BT
Program in Human Molecular Biology and Genetics and Division of Endocrinology, Metabolism, and Diabetes, University of Utah School of Medicine, Salt Lake City, UT 84112, USA.
Kim
Jaetaek
J
Wende
Adam R
AR
Theobald
Heather A
HA
Tuinei
Joseph
J
Buchanan
Jonathan
J
Guo
Aili
A
Zaha
Vlad G
VG
Davis
Don K
DK
Schell
John C
JC
Boudina
Sihem
S
Wayment
Benjamin
B
Litwin
Sheldon E
SE
Shioi
Tetsuo
T
Izumo
Seigo
S
Birnbaum
Morris J
MJ
Abel
E Dale
ED
D000222:Adaptation, Physiological; D000818:Animals; D006332:Cardiomegaly / Q000201:enzymology*; D005227:Fatty Acids / Q000378:metabolism; D005786:Gene Expression Regulation; D007527:Isoenzymes / Q000037:antagonists & inhibitors; D051379:Mice; D008817:Mice, Mutant Strains; D008928:Mitochondria / Q000502:physiology*; D032383:Myocytes, Cardiac / Q000201:enzymology; D010084:Oxidation-Reduction; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000502:physiology*; D010805:Physical Conditioning, Animal; D020033:Protein Isoforms / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D015398:Signal Transduction; D000099293:Protein Kinase C-lambda; D000099221:Protein Kinase C zeta
D005227:Fatty Acids; D007527:Isoenzymes; D019869:Phosphatidylinositol 3-Kinases; D020033:Protein Isoforms; D011493:Protein Kinase C; D051057:Proto-Oncogene Proteins c-akt; D000099293:Protein Kinase C-lambda; D000099221:Protein Kinase C zeta