Identification of IQ motif-containing GTPase-activating protein 1 as a regulator of long-term ketosis.

ABSTRACT: IQ motif-containing GTPase-activating protein 1 (IQGAP1) is a ubiquitously expressed scaffolding protein that integrates multiple cellular processes, including motility, adhesion, and proliferation, but its role in metabolism is unknown. Here, we show that IQGAP1 is induced upon fasting and regulates ?-oxidation of fatty acids and synthesis of ketone bodies in the liver. IQGAP1-null (Iqgap1-/-) mice exhibit reduced hepatic PPAR? transcriptional activity, as evidenced during fasting, after ketogenic diet, and upon pharmacological activation. Conversely, we found that the activity of fed-state sensor mTORC1 is enhanced in Iqgap1-/- livers, but acute inhibition of mTOR in Iqgap1-/- mice was unable to rescue the defect in ketone body synthesis. However, reexpressing IQGAP1 in the livers of Iqgap1-/- mice was sufficient to promote ketone body synthesis, increase PPAR? signaling, and suppress mTORC1 activity. Taken together, we uncover what we believe to be a previously unidentified role for IQGAP1 in regulating PPAR? activity and ketogenesis.

SUBMITTER: Erickson HL 

PROVIDER: S-EPMC6238733 | biostudies-literature | 2018 Nov

REPOSITORIES: biostudies-literature