Hypothesis

In MASLD, zone 3 hepatocytes exhibit heightened Wnt/β‑catenin signaling that directly upregulates transferrin receptor 1 (TFRC) and suppresses ferroportin, expanding the labile iron pool. This iron surplus fuels lipid peroxidation and triggers ferroptosis, which in turn drives the aging hepatocyte gene signature (AHGS) and senescence. Concurrent Wnt activity also sustains neoplastic potential, making zone 3 a nexus of iron‑dependent cell death, aging, and cancer risk. Inhibiting Wnt signaling should reduce TFRC‑mediated iron import, lower ferroptosis susceptibility, and attenuate AHGS, thereby reversing zone‑3‑specific aging and fibrosis.

Mechanistic Reasoning

1. Wnt/β‑catenin → iron homeostasis – Canonical Wnt signaling increases TFRC transcription and decreases ferroportin expression, a regulatory link documented in cancer cells (3). In zone 3 hepatocytes, constitutively active Wnt/β‑catenin (3) would therefore raise intracellular iron, promoting the Fenton reaction and lipid ROS.
2. Iron‑driven ferroptosis → aging – Excess labile iron catalyzes peroxidation of polyunsaturated fatty acids, a core ferroptotic trigger. Ferroptotic stress activates DNA‑damage responses and p16^INK4a^ expression, contributing to the AHGS observed in aged hepatocytes (1).
3. Zone‑3 specificity – Zone 3 is the primary site of early fibrosis (2) and harbors the highest Wnt/β‑catenin activity (3). This creates a spatial match between iron overload, ferroptosis, and aging markers.
4. Therapeutic implication – Pharmacological Wnt inhibition (e.g., PORCN antagonists) combined with a ferroptosis inhibitor (liproxstatin‑1, as shown effective in preclinical MASLD reversal (4)) should synergistically lower iron import, block lipid peroxidation, reduce AHGS, and limit senescent cell accumulation.

Testable Predictions

• Prediction 1: In liver biopsies from MASLD patients, zone 3 hepatocytes will show higher TFRC protein levels and lower ferroportin compared to zone 1/2, correlating with AHGS scores.
• Prediction 2: Treatment of aged MASLD mice with a PORCN inhibitor will decrease zone‑3 labile iron (measured by calcein‑AM quenching) and lipid ROS (C11‑BODIPY) without altering total hepatic iron.
• Prediction 3: Dual PORCN inhibition + ferroptosis inhibition will produce a greater reduction in AHGS‑positive hepatocytes and fibrosis (Sirius Red area) than either monotherapy.
• Prediction 4: Genetic knockdown of TFRC specifically in zone 3 hepatocytes (using AAV8‑TBG‑Cre with a zona‑3‑specific enhancer) will mimic the protective effects of Wnt inhibition on ferroptosis and aging markers.

Falsifiability

If zone 3 hepatocytes do not exhibit elevated TFRC or if Wnt inhibition fails to reduce labile iron and ferroptosis despite confirming pathway blockade, the hypothesis would be refuted. Similarly, if combined Wnt and ferroptosis inhibition does not improve AHGS or fibrosis beyond monotherapy effects, the proposed synergistic mechanism is unsupported.

References

[1] https://pmc.ncbi.nlm.nih.gov/articles/PMC12810195/ [2] https://pmc.ncbi.nlm.nih.gov/articles/PMC2346454/ [3] https://pmc.ncbi.nlm.nih.gov/articles/PMC8319533/ [4] https://medicalxpress.com/news/2026-01-drug-candidate-reverses-metabolic-liver.html }