Increased de novo lipogenesis (DNL) contributes to lipid disturbances prevalent in insulin resistant (IR) subjects, including dyslipidemia and NAFLD; however, the specific carbon sources that maintain DNL during hepatic IR remain unknown. To address this question, antisense oligonucleotides (ASOs) targeting glucokinase (GCK) , ketohexokinase (KHK) , lactate dehydrogenase (LDHA) , and glutamic-pyruvic transaminase 2 (GPT2) were applied to restrict substrate influx from specific lipogenic precursors. Subsequently, the rates of DNL were assessed via the deuterated water method, and triglyceride (TG) content was measured in both insulin-sensitive regular chow (RC) fed and IR six-week high-fat diet (HFD) fed C57BL6/J mice. In RC mice, there were no significant differences in hepatic DNL as a result of treatment with any ASO. Furthermore, TG content remained unchanged by most ASOs in the RC cohort, but was increased in the liver with the LDHA ASO (Con: 7.4±0.2 μg/mg; LDHA: 16.9±1.2 μg/mg; p<.001) and decreased in circulation with the GCK ASO (Con:84.8±6.3 mg/dL; GCK:54.5±5.8 mg/dL; p<.01) . In the HFD cohort, DNL, hepatic TG content, and circulating TGs were all reduced by restricting lipogenic carbon entry from glucose (GCK ASO vs. Con: DNL -69.2%±3.6, p<.01; Hep TG -59.2%±4.4, p<.05; Cir TG -35.7%±3.7, p<.001) , lactate (LDHA ASO vs. Con: DNL -33.1%±9.1, p<.05; Hep TG -25.8%±7.4, p<.05; Cir TG -18.0%±8.0, NS) , and alanine (GPT2 ASO vs. Con: DNL -48.1%±9.8, p<.01; Hep TG -45.5%±8.9, p<.01; Cir TG -23.2%±5.3, p<.01) .

Conclusion: RC fed mice maintain DNL despite restricting specific carbon precursors; however, in HFD-fed mice, glucose, lactate, and alanine are all necessary substrates for maintaining aberrantly elevated rates of DNL, and any substrate restraint is associated with reduced DNL. These findings expound how specific carbon fluxes support DNL in IR and may inform the development of novel therapies for dyslipidemia.


J.W.Strober: None. L.M.Paolella: None. R.Suh: None. B.T.Hubbard: None. S.Murray: Employee; Ionis Pharmaceuticals. D.F.Vatner: None.


NIH T32 (DK007058) NIH R (DK124272)

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