Figure 3. Nam induces β-OHB downstream of PGC1α to augment PGE₂.

a, Renal RNA sequencing 24h after IRI or sham operation in controls vs. iNephPGC1α mice with enumerated transcripts. b, Pathway analysis of 1160 transcripts unique to post-ischemic iNephPGC1α mice graphed by −log₁₀[Benjamini-Hochberg-corrected p-value]. Dashed line at p<0.05. c, de novo NAD biosynthetic pathway adapted from KEGG (www.genome.jp/kegg). Trp=tryptophan, Kyn=kynurenine, Am=amino, Na=nicotinate. d–f, Heatmaps (red=lower, blue=higher) of intrarenal expression for de novo pathway from KO vs. WT; 24h after sham vs. IRI; and iNephPGC1α vs. controls (n=6/group). P-values by ANOVA. g, Relative renal Nam and NAD 4h after indicated Nam dose. P-value by ANOVA. h, Conditioned-media-PGE₂ of renal tubular cells after HCAR2 knockdown with and without HCAR2 stimulation (+,niacin 10mM, n=6/group). i, PGE₂ from renal cells following Nam (1μM for 24h) with and without NAMPT inhibitor FK866 (10nM, n=6/group). j–l, Intracellular NAD, conditioned-media beta-hydroxybutyrate (β-OHB), and conditioned-media PGE₂ in PGC1α knockdown cells (n=6/group). m–o, Relative renal NAD, β-OHB, and PGE₂ in control vs. iNephPGC1α mice (n=6/group). *p<0.05, **p<0.01, ***p<0.001. p, Renal epithelial PGC1α coordinately upregulates de novo NAD biosynthesis, in the absence of which Nam is utilized through the NAMPT-salvage pathway to generate NAD. Consequently, β-OHB accumulates, which signals HCAR2 to induce PGE₂. Error bars SEM.