No abstract

Circulating increases in branched chain amino acid (BCAA) levels have long been associated with type 2 diabetes and metabolic syndrome. Emerging data also suggest that BCAA catabolism may play a role in heart failure progression. It is hypothesized that decreased catabolism, rather than increased consumption of BCAAs, is responsible for these correlations. Branched chain ketoacid (BCKA) dehydrogenase (BCKDH) kinase (BCKDK) is a negative regulator of BCAA catabolism through its inhibitory phosphorylation of the BCKDH E1a subunit. Using the BCKDK inhibitor molecule BT2, we demonstrate here a reduction of BCAA, BCKA and tissue p-BCKDH levels concomitant with improved glucose tolerance and reduced insulin levels in diet-induced obese mice after only one day of treatment. To investigate the mechanisms underlying this protection, we assessed plasma biomarkers and tissue gene expression after fasting and re-feeding in glucose intolerant high fat diet-fed animals. Remarkably, BT2 treated animals demonstrated reduced plasma glucose levels after re-feed, which was accompanied by dramatic reductions in plasma insulin levels, reduced activation of Akt in peripheral tissues, and a failure to suppress plasma free fatty acids and lipolytic machinery in adipose tissue. RNAseq was performed in liver to assess changes in gene expression profiles, and while over 400 genes were differentially regulated in vehicle treated re-fed mice compared with vehicle treated fasted mice, there were no differentially regulated genes in BT2 re-fed animals compared with BT2 fasted animals. These data suggest that activation of BCAA catabolism with the BCKDK inhibitor BT2 impairs the systemic response to feeding. Disclosure E. Bollinger: Employee; Self; Pfizer Inc. C.P. Siddall: Employee; Self; Pfizer Inc. Employee; Spouse/Partner; Vertex Pharmaceuticals. T. Greizer: None. J.L. Libera: None. G. Hariri: None. E.E. Pashos: Employee; Self; Pfizer Inc. A. Shipstone: None. A. Hadjipanayis: None. Z. Sun: None. G. Xing: None. M.F. Clasquin: Employee; Spouse/Partner; Merck & Co., Inc. Employee; Self; Pfizer Inc. B.B. Zhang: Employee; Spouse/Partner; Janssen Pharmaceuticals, Inc. Employee; Self; Pfizer Inc. Other Relationship; Self; Eli Lilly and Company. R.A. Miller: Employee; Self; Pfizer Inc. R. Roth Flach: Employee; Self; Pfizer Inc.