Fig 1: Increased reliance on de novo purine synthesis in H3K27M cells.A.) Schematic of purine synthetic metabolic pathways showing where the purine de novo and salvage pathways converge to form guanylate purines from IMP and free purine bases, respectively. B. and C.) Ratio of 15N-glutamine:2D-Hpx stable isotope tracer label incorporation into GMP (B.) and AMP (C.) in untreated DIPGXIII H3K27M-isogenic cell lines. D.) Publicly available RNAseq Z-score data for HPRT1 transcript expression from pediatric high-grade gliomas (pHGG) was obtained through PedCBioPortal and filtered to include only samples with known H3 mutational status (for both H3F3A and HIST1H3B) to include all known H3WT (n=59)and combined H3K27M (H3F3A-mut+HIST1H3B-mut) samples (n=44) E.) and F.) Immunoblots of HGPRT and IMPDH1 (E.) and HGPRT (F.) expression in DMG-H3K27M isogenic paired cell lines. Densitometric values were calculated using ImageJ software and expression values were normalized to H3K27M-KO cells. Expression ratios are listed below the blot images. Statistical analyses were performed using two-tailed t-tests.