Figure 4.

FAMIN Variants Impact on Central Purine Routing

(A) IMP levels in control and FAMIN-silenced HepG2 cells 24 h after transfection (n = 3).

(B) Inosine and hypoxanthine levels in control and FAMIN-silenced HepG2 cells 48 h after transfection (n = 6).

(C and D) Adenine, adenosine, (C) and ATP levels (D) in Famin^p.254I, Famin^p.254V, and Famin^p.284R M1 macrophages (n = 12).

(E) Metabolic fate of [¹³C₁₀¹⁵N₅] adenosine after a 3-h pulse of M1 macrophages (n = 6; mean). Schematic representation of central purine metabolism. Adenosine deamination into inosine releases ¹⁵N as ammonia, generating a [¹³C₁₀¹⁵N₄] isotopomer (brown). Phosphorolytic cleavage of inosine into hypoxanthine and [¹³C₅] R1P, yielding the [¹³C₅¹⁵N₄] isotopomer (blue). Adenosine conversion to AMP without loss of label (purple). Phosphorolytic cleavage of fully labeled MTA generates [¹³C₅¹⁵N₅] adenine (green) and [¹³C₅] 5′-methylthioribose-1-phosphate. Fractions of differently labeled states (averaged across Famin^p.254I, Famin^p.254V, and Famin^p.284R genotypes) depicted as pie charts. ADA, adenosine deaminase; ADK, adenosine kinase; APRT, adenine phosphoribosyl transferase; HPRT, hypoxanthine-guanine phosphoribosyl transferase; MTAP, MTA phosphorylase; PNP, purine nucleoside phosphorlyase.

(F–H) Fraction of guanosine (F), guanine (G), or GTP (H) labeled as the indicated isotopomer in M1 macrophages after a [¹³C₁¹⁵N₂] guanosine pulse (n = 6).

(I) Metabolite levels (gray dots) in Famin^p.254I versus Famin^p.284R M1 macrophages depicted as volcano plot. False discovery rate (FDR)-controlled LC-MS features (black dots), select metabolites in red (n = 6).

(J) Immunoblots (IBs) with indicated antibodies in M1 macrophages (n = 3).

Data represented as mean ± SEM. ^∗p < 0.05, ^∗∗p < 0.01, and ^∗∗∗p < 0.001 (unpaired, two-tailed Student’s t test or one-way ANOVA).