Fig 4. Loss of dhgd-1 activates the expression of ketone body metabolism genes.

(A) Gene expression pathway enrichment analysis for animals with and without vitamin B12 (B12). (B) RNA-seq data for propionate shunt (top) and ketone body metabolism genes (bottom). TPM–transcripts per million. Gene categories were annotated in [35]. (C) Supplementation of 3HB or AA ethyl esters partially rescues lethality of Δdhgd-1 mutant animals. Acetate ethyl ester was used as a negative control. (D) Model for the effect of dhgd-1 mutation on ketone body production. (E) Contribution of propionate shunt (dhgd-1), lysine (aass-1) and leucine (mccc-1) degradation pathways and vitamin B12 to the generation of energy (ATP) and ketone bodies (3HB and acetoacetate). Metabolite production potentials were estimated by maximizing their output fluxes in corresponding FBA formulations. (F) Tissue expression of genes comprising the canonical vitamin B12-dependent propionate degradation pathway and propionate shunt pathway from a published single-cell RNA-seq dataset [39]. (G) Model for ketone body exchange between C. elegans intestine and muscle in the presence and absence of vitamin B12. All panels: the means of 3 or more groups were compared with ANOVA, followed by unpaired t test (*p < 0.05, **p < 0.01, ***p < 0.001). Sequencing data underlying Fig 4A and 4B have been deposited in GEO under accession code GSE201645. The data underlying Fig 4B, 4C, 4E, and 4F can be found in S1 Data. FDR, false discovery rate; WT, wild type.