Inhibiting Wnt/β-catenin-mTOR signaling enhances autophagy and porphyrin clearance in murine porphyrias with hepatic involvement.

Porphyrias are rare metabolic disorders arising from defects in heme biosynthesis, leading to accumulation of toxic porphyrin intermediates, mitochondrial dysfunction, and liver injury. Current therapies are limited in efficacy, emphasizing the need for novel treatments. Prior studies showed hepatocyte-specific β-catenin deletion attenuates porphyrin accumulation and liver injury in 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC)-induced porphyria. We hypothesized that inhibiting components of the Wnt-β-catenin-glutamine synthesis (GS) pathway reduces heme synthesis and also enhances porphyrin clearance by activating autophagy and improving mitochondrial quality control. We combined pharmacologic Wnt inhibition and hepatocyte-specific GS deletion in murine models of porphyria. Readouts included spatial transcriptomics, targeted metabolomics, immunohistochemistry, confocal mt-Keima imaging, high-resolution respirometry, and transmission electron microscopy. Human liver biopsies and explants from porphyria patients were also examined by dual-label immunohistochemistry. Wnt inhibition during DDC suppressed upregulation of heme biosynthesis genes, reduced porphyrin intermediate accumulation, and enhanced autophagic flux. GS deletion attenuated porphyrin biosynthesis by limiting intracellular glutamine. Wnt and GS deletion produced additive increases in autophagy, restored zonation, and further reduced porphyrin accumulation. Wnt inhibition restored mitophagy, whereas GS deletion primarily improved mitochondrial coupling efficiency. Wnt inhibition also decreased fibrosis in a genetic mouse model of porphyria. Patient samples mirrored murine findings, with heme enzymes and autophagy inversely correlated with β-catenin expression in porphyria cutanea tarda. By disrupting Wnt-GS signaling, we establish a link between increased autophagy, reduced porphyrin formation, and heme pathway regulation in mouse and human liver. These findings identify the Wnt signaling pathway as a potential therapeutic target in porphyria.Abbreviations: ALA: δ-Aminolevulinic acid; AIP: acute intermittent porphyria; ALAS: aminolevulinic acid synthase; ALAD: aminolevulinic acid dehydratase; ALP: alkaline phosphatase: AST: aspartate aminotransferase; ALT: alanine aminotransferase; DAB: 3,3'-diaminobenzidine; DDC: 3,5-diethoxycarbonyl-1,4-dihydrocollidine; EPP: erythropoietic protoporphyria; Fech: ferrochelatase; GAPDH: glyceraldehyde 3-phosphate dehydrogenase; GS: glutamine synthesis; H&E: hematoxylin and eosin: HO-1: heme oxygenase 1; IHC: immunohistochemistry; KO: knockout; LAMP1: lysosomal associated membrane protein 1; LC3: microtubule-associated protein 1 A/1B-light chain 3; mTOR: mechanistic target of rapamycin; PBG: porphobilinogen; PBS: phosphate-buffered saline; PP-IX: protoporphyrin-IX; PCT: porphyria cutanea tarda; RCR: respiratory control ratio; SQSTM1/p62: sequestosome 1; TEM: transmission electron microscopy; Wnt-I: Wnt-C59 (inhibitor).