Fig. 4: Hypermetabolism leads to the reprioritization of acetyl-CoA in neurons.

A Fates of coenzyme A, the primary product of pantothenate, including lipid biosynthesis through acyl carrier protein (ACP), lysine degradation via α-aminoadipate semialdehyde synthase (AASS), the folate cycle through 10-formyltetrahydrofolate dehydrogenase (FDH), and acetyl-CoA biosynthesis. Acetyl-CoA serves as a metabolic hub involved in acetylcholine (ACh) production, bioenergetics (TCA cycle), lipid biosynthesis and protein acetylation. B Volcano plot showing protein expression changes of proteins involved in acetyl-CoA biosynthesis between MUT and WT. Thresholds: FDR = 0.01, log2(FC) = 1. C Relative abundance of acetyl-CoA measured using UC¹³-glucose metabolic tracing, calculated as the total sum of the labeled fraction (m + 1 and m + 2). D Expression levels of FASN, involved in fatty acid biosynthesis in the cytosol and MECR, involved in the last step of fatty acid biosynthesis in mitochondria. E Relative abundance of acetylcholine measured using UC¹³-glucose metabolic tracing, calculated as the total sum of the labeled fraction (m + 1 to m + 4). F Left, expression levels of proteins involved in acetylcholine synthesis and processing. Referred to the control group. Right, scheme depicting the synthesis, transport and hydrolysis of the neurotransmitter acetylcholine (Ach)³⁸. Created in BioRender. Torregrosa, R. (2025), https://BioRender.com/0gy0ypl. G Pathway Enrichment Analysis of Reactome terms enriched pathways in MUT (52 + 54%) vs WT. Differentially downregulated pathways are indicated by gene ratio (counts) and FDR (adj.p-value). H Heatmap of selected proteins related to histone modifications. I Heatmap of selected proteins related to DNA modifiers and chromatin remodeling. Data shown as mean ± standard deviation, *p < 0.05, **p < 0.01, ***p < 0.001, by One-Way ANOVA followed by Tukey´s multiple comparison post-hoc test. J Representative cropped immunoblot of total H3 and pan-acetylated (PanKAc) H3 in iPSC-derived MN. K Quantification of (J) as the ratio total H3/ PanKAc H3. n = 2 biological replicates (cell lines). L Proposed model: ATP synthase deficiency caused by the truncating MT-ATP6 mutation triggers a metabolic rewiring, leading to hypermetabolism. This reflects an increased consumption of pantothenate possibly due to increased demands of acetyl-CoA for biosynthetic pathways, limiting the availability for histone acetylation. Consequently, this drives epigenetic changes influencing gene expression and likely modulating an adaptation.