Regulation of energy substrate utilization and hepatic insulin sensitivity by phosphatidylcholine transfer protein/StarD2.
Phosphatidylcholine transfer protein (PC-TP, also known as StarD2) is a highly specific intracellular lipid binding protein with accentuated expression in oxidative tissues. Here we show that decreased plasma concentrations of glucose and free fatty acids in fasting PC-TP-deficient (Pctp(-/-)) mice are attributable to increased hepatic insulin sensitivity. In hyperinsulinemic-euglycemic clamp studies, Pctp(-/-) mice exhibited profound reductions in hepatic glucose production, gluconeogenesis, glycogenolysis, and glucose cycling. These changes were explained in part by the lack of PC-TP expression in liver per se and in part by marked alterations in body fat composition. Reduced respiratory quotients in Pctp(-/-) mice were indicative of preferential fatty acid utilization for energy production in oxidative tissues. In the setting of decreased hepatic fatty acid synthesis, increased clearance rates of dietary triglycerides and increased hepatic triglyceride production rates reflected higher turnover in Pctp(-/-) mice. Collectively, these data support a key biological role for PC-TP in the regulation of energy substrate utilization.
Scapa
Erez F
EF
Department of Medicine, Division of Gastroenterology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA.
Pocai
Alessandro
A
Wu
Michele K
MK
Gutierrez-Juarez
Roger
R
Glenz
Lauren
L
Kanno
Keishi
K
Li
Hua
H
Biddinger
Sudha
S
Jelicks
Linda A
LA
Rossetti
Luciano
L
Cohen
David E
DE
D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism; D018929:Cell Culture Techniques; D003433:Crosses, Genetic; D004734:Energy Metabolism; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005786:Gene Expression Regulation; D015309:Glucose Clamp Technique; D005951:Glucose Tolerance Test; D022781:Hepatocytes / Q000166:cytology / Q000502:physiology; D007328:Insulin / Q000502:physiology*; D008055:Lipids / Q000502:physiology; D008099:Liver / Q000502:physiology*; D051379:Mice; D018345:Mice, Knockout; D049294:Phospholipid Transfer Proteins / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D014280:Triglycerides / Q000378:metabolism*
D001786:Blood Glucose; D002352:Carrier Proteins; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D008055:Lipids; D049294:Phospholipid Transfer Proteins; D012333:RNA, Messenger; D014280:Triglycerides