Genetic ablation of calcium-independent phospholipase A2gamma prevents obesity and insulin resistance during high fat feeding by mitochondrial uncoupling and increased adipocyte fatty acid oxidation.
Phospholipases are critical enzyme mediators participating in many aspects of cellular function through modulating the generation of lipid 2nd messengers, membrane physical properties, and cellular bioenergetics. Here, we demonstrate that mice null for calcium-independent phospholipase A(2)γ (iPLA(2)γ(-/-)) are completely resistant to high fat diet-induced weight gain, adipocyte hypertrophy, hyperinsulinemia, and insulin resistance, which occur in iPLA(2)γ(+/+) mice after high fat feeding. Notably, iPLA(2)γ(-/-) mice were lean, demonstrated abdominal lipodystrophy, and remained insulin-sensitive despite having a marked impairment in glucose-stimulated insulin secretion after high fat feeding. Respirometry of adipocyte explants from iPLA(2)γ(-/-) mice identified increased rates of oxidation of multiple different substrates in comparison with adipocyte explants from wild-type littermates. Shotgun lipidomics of adipose tissue from wild-type mice demonstrated the anticipated 2-fold increase in triglyceride content after high fat feeding. In sharp contrast, the adipocyte triglyceride content was identical in iPLA(2)γ(-/-) mice fed either a standard diet or a high fat diet. Respirometry of skeletal muscle mitochondria from iPLA(2)γ(-/-) mice demonstrated marked decreases in state 3 respiration using multiple substrates whose metabolism was uncoupled from ATP production. Shotgun lipidomics of skeletal muscle revealed a decreased content of cardiolipin with an altered molecular species composition thereby identifying the mechanism underlying mitochondrial uncoupling in the iPLA(2)γ(-/-) mouse. Collectively, these results identify iPLA(2)γ as an obligatory upstream enzyme that is necessary for efficient electron transport chain coupling and energy production through its participation in the alterations of cellular bioenergetics that promote the development of the metabolic syndrome.
Mancuso
David J
DJ
Division of Bioorganic Chemistry and Molecular Pharmacology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Sims
Harold F
HF
Yang
Kui
K
Kiebish
Michael A
MA
Su
Xiong
X
Jenkins
Christopher M
CM
Guan
Shaoping
S
Moon
Sung Ho
SH
Pietka
Terri
T
Nassir
Fatiha
F
Schappe
Timothy
T
Moore
Kristin
K
Han
Xianlin
X
Abumrad
Nada A
NA
Gross
Richard W
RW
D017667:Adipocytes / Q000378:metabolism*; D000818:Animals; D015153:Blotting, Western; D001823:Body Composition; D002118:Calcium / Q000378:metabolism*; D004041:Dietary Fats / Q000008:administration & dosage*; D004734:Energy Metabolism; D005227:Fatty Acids / Q000737:chemistry* / Q000378:metabolism; D054513:Group IV Phospholipases A2 / Q000502:physiology*; D007328:Insulin / Q000378:metabolism; D007333:Insulin Resistance; D050356:Lipid Metabolism; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D008931:Mitochondria, Muscle / Q000502:physiology*; D018482:Muscle, Skeletal / Q000166:cytology / Q000378:metabolism; D009765:Obesity / Q000517:prevention & control*; D010084:Oxidation-Reduction; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014280:Triglycerides / Q000378:metabolism
D004041:Dietary Fats; D005227:Fatty Acids; D007328:Insulin; D012333:RNA, Messenger; D014280:Triglycerides; D054513:Group IV Phospholipases A2; D002118:Calcium
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