Mount Sinai Researchers Identify Aryl Hydrocarbon Receptor as Molecular Brake Hindering Nerve Fiber Regeneration

Icahn School of Medicine researchers find that blocking the AHR protein can trigger axonal regeneration and restore function after spinal cord and nerve injuries.

By: AXL Media

Published: Apr 2, 2026, 4:39 AM EDT

Source: Information for this report was sourced from Mount Sinai Health System.

The Biological Barrier to Neural Repair

The limited capacity of the adult mammalian nervous system to repair itself has long been a primary obstacle in treating traumatic injuries. When axons, the long fibers responsible for transmitting signals between neurons, are severed, the body’s natural response often prioritizes cellular survival over the reconstruction of lost connections. A new study published in the journal Nature has identified the aryl hydrocarbon receptor (AHR) as the specific molecular "brake" responsible for this restorative stagnation. Investigators at Mount Sinai found that this protein dictates how a neuron allocates its internal resources following an injury, often forcing the cell into a defensive posture that precludes active growth.

Deciphering the Stress Versus Growth Switch

The research team, led by Dr. Hongyan Zou, discovered that AHR functions as a regulatory switch that balances a neuron's need to manage stress with its ability to regenerate. Following a traumatic event, AHR signaling becomes active, focusing the cell's energy on proteostasis—a quality control process that maintains protein integrity during periods of high cellular stress. While this protective mechanism ensures the neuron's immediate survival, it simultaneously halts the production of new proteins essential for extending axonal fibers. By removing or pharmacologically blocking AHR, the researchers were able to release this biological brake, effectively "tricking" the neurons into prioritizing the rebuilding of damaged connections.

Restoring Function in Spinal and Peripheral Models

The implications of this discovery were tested using mouse models of both peripheral nerve and spinal cord injuries. In these experiments, inhibiting AHR signaling led to a marked increase in the effectiveness of axonal regrowth. More importantly, the physical regeneration of these fibers translated into tangible clinical improvements, as the treated subjects demonstrated a significant recovery of both motor and sensory functions. This suggests that the AHR pathway is a universal regulator of regenerative capability across different parts of the nervous system, providing a high-value target for future therapeutic interventions in humans.