Branched-chain ketoacid overload inhibits insulin action in the muscle

Dipsikha Biswas, Khoi T. Dao, Angella Mercer, Andrew M. Cowie, Luke Duffley, Yassine El Hiani, Petra C. Kienesberger, Thomas Pulinilkunnil

Producción científica: Contribución a una revistaArtículorevisión exhaustiva

36 Citas (Scopus)

Resumen

Branched-chain a-keto acids (BCKAs) are catabolites of branched-chain amino acids (BCAAs). Intracellular BCKAs are cleared by branched-chain ketoacid dehydrogenase (BCKDH), which is sensitive to inhibitory phosphorylation by BCKD kinase (BCKDK). Accumulation of BCKAs is an indicator of defective BCAA catabolism and has been correlated with glucose intolerance and cardiac dysfunction. However, it is unclear whether BCKAs directly alter insulin signaling and function in the skeletal and cardiac muscle cell. Furthermore, the role of excess fatty acids (FAs) in perturbing BCAA catabolism and BCKA availability merits investigation. By using immunoblotting and ultra-performance liquid chromatography MS/MS to analyze the hearts of fasted mice, we observed decreased BCAA-catabolizing enzyme expression and increased circulating BCKAs, but not BCAAs. In mice subjected to diet-induced obesity (DIO), we observed similar increases in circulating BCKAs with concomitant changes in BCAA-catabolizing enzyme expression only in the skeletal muscle. Effects of DIO were recapitulated by simulating lipotoxicity in skeletal muscle cells treated with saturated FA, palmitate. Exposure of muscle cells to high concentrations of BCKAs resulted in inhibition of insulin-induced AKT phosphorylation, decreased glucose uptake, and mitochondrial oxygen consumption. Altering intracellular clearance of BCKAs by genetic modulation of BCKDK and BCKDHA expression showed similar effects on AKT phosphorylation. BCKAs increased protein translation and mTORC1 activation. Pretreating cells with mTORC1 inhibitor rapamycin restored BCKA’s effect on insulin-induced AKT phosphorylation. This study provides evidence for FA-mediated regulation of BCAA-catabolizing enzymes and BCKA content and highlights the biological role of BCKAs in regulating muscle insulin signaling and function.

Idioma originalEnglish
Páginas (desde-hasta)15597-15621
Número de páginas25
PublicaciónJournal of Biological Chemistry
Volumen295
N.º46
DOI
EstadoPublished - nov. 13 2020

Nota bibliográfica

Funding Information:
Funding and additional information—This work was supported by Natural Sciences and Engineering Research Council of Canada Grant RGPIN-2020-05906, Diabetes Canada Grants NOD_OG-3-15-5037-TP and NOD_SC-5-16-5054-TP, and New Brunswick Health Research Foundation grants (to T. P.); D. B., was funded by postdoctoral fellowships from New Brunswick Health Research Foundation and Dalhousie Medicine New Brunswick.

Publisher Copyright:
© 2020 Biswas et al.

ASJC Scopus Subject Areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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