Fig 2: Schematic of proposed PDH regulation by GCN5L1. A combination of nutrient excess and aging leads to increased GCN5L1 expression (Thapa et al., 2017; Thapa, Manning, Stoner, et al., 2020), which results in significantly increased PDHA1 lysine acetylation. Increased PDHA1 acetylation results in decreased PDH enzymatic activity, which contributes to the diastolic dysfunction observed in obese, aged mice.

Fig 3: GCN5L1 promotes PDHA1 acetylation and inhibits pyruvate dehydrogenase activity. (a, b) PDHA1 phosphorylation (S293) and lysine acetylation in WT and KO mice following LFD or HFD. N = 3–5; two-way ANOVA; *p < 0.05 relative to WT LFD, # p < 0.05 to WT HFD (c) PDH activity in WT and KO mice following LFD or HFD. N = 3–5; two-way ANOVA; *p < 0.05 relative to WT LFD, # p < 0.05 to WT HFD. (d) Linear regression of PDH activity and acetylation levels in WT and KO mice following LFD or HFD.

Fig 4: Acetylation of PDHA1 directly reduces its enzymatic activity. (a) Schematic of human PDHA1 showing published lysine acetylation sites. (b, c) GCN5L1 KD AC16 cells were transfected with Myc-tagged wildtype PDHA1 (WT-Myc), a non-acetylated PDHA1 mimic in which lysines K18/K39/K244/K321/K336 were replaced with arginine (5KR-Myc), and an acetylated PDHA1 mimic where lysines K18/K39/K244/K321/K336 were replaced with glutamine (5KQ-Myc). N = 6; one-way ANOVA; *p < 0.05 relative to WT, # p < 0.05 to 5KR.