1510-P: Lipid-Induced Renal Cortical Insulin Resistance Perturbs Gluconeogenic and Oxidative Metabolism via an sn-1,2-diacylglycerol-PKCe-Insulin Receptor Kinase Axis In Vivo
Recently, our group demonstrated that 3-week high fat diet feeding (HFD) impairs insulin signaling in the renal cortex at the level of the insulin receptor kinase (IRK). Specifically, IRKY1162 and AKTS473 phosphorylation were reduced by ~50% during hyperinsulinemic-euglycemic clamp (HEC); however, i...
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Veröffentlicht in: | Diabetes (New York, N.Y.) N.Y.), 2023-06, Vol.72 (Supplement_1), p.1 |
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Zusammenfassung: | Recently, our group demonstrated that 3-week high fat diet feeding (HFD) impairs insulin signaling in the renal cortex at the level of the insulin receptor kinase (IRK). Specifically, IRKY1162 and AKTS473 phosphorylation were reduced by ~50% during hyperinsulinemic-euglycemic clamp (HEC); however, it is unknown how renal cortical insulin resistance (IR) may affect gluconeogenic (GNG) and oxidative metabolism. To address this, here we measure renal cortical GNG fluxes in vivo using Q-Flux. In regular chow (RC) fed mice, hyperinsulinemia significantly suppressed mitochondrial pyruvate carboxylase (PC), as PC flux relative to α-ketoglutarate dehydrogenase flux (VPC/VOGDH) was 1.25 under basal conditions, but decreased by ~50%, to 0.57 during HEC. Similarly, PEPCK flux relative OGDH flux (VPEPCK/VOGDH) was reduced by ~60% during HEC. In contrast, insulin failed to suppress both PC and PEPCK fluxes with HFD. Using a [13C6]glucose tracer, we also find insulin-stimulated mitochondrial pyruvate oxidation to be impaired by ~30% with HFD. Mechanistically, we previously found HFD led to a 2-fold increase in plasma membrane (PM) sn-1,2-diacylglycerol (DAG) and a 4-fold increase in Protein Kinase Cε (PKCε) translocation, suggesting renal cortical IR may be mediated by an sn-1,2-DAG-PKCε-IRK axis. We further interrogated this possibility here by assessing inhibitory phosphorylation at IRKT1150, the key target of PKCε, finding a 42% increase with HFD. In addition, IRKT1150A knockin mice, whose IRK cannot be phosphorylated by PKCε, were protected from HFD-induced signaling and pyruvate oxidation defects.
Conclusion: HFD inhibits renal cortical insulin signaling at the level of the IRK, which is associated with perturbed mitochondrial GNG and oxidative metabolism. IRKT1150A mice are protected from HFD-induced defects, indicating a PM sn-1,2-DAG-PKCε-pIRKT1150 mechanism for lipid-induced renal cortical IR. |
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ISSN: | 0012-1797 1939-327X |
DOI: | 10.2337/db23-1510-P |