Scientists at the Icahn School of Medicine at Mount Sinai have identified a molecular mechanism that limits the regenerative capacity of damaged nerve cells. The research, reported in Nature, focuses on a protein called the aryl hydrocarbon receptor (AHR) that appears to suppress the ability of injured neurons to rebuild damaged axons, the long extensions of nerve cells responsible for transmitting signals throughout the nervous system.
In adult mammals, neurons have limited capacity to regenerate damaged axons, which often results in persistent complications involving movement and sensation following nerve or spinal cord injuries. Researchers found that AHR functions as a regulatory brake that redirects neurons toward managing cellular stress rather than repairing damaged connections. When the research team removed AHR from neurons or used drugs to inhibit its activity, damaged axonal fibers regenerated more effectively. Laboratory experiments using mouse models demonstrated that suppressing AHR following peripheral nerve damage and spinal cord injury led to improved recovery of both movement and sensation.
The underlying mechanism involves a trade-off between two competing cellular priorities. Active AHR signaling supports a protective response that helps injured neurons maintain protein quality control, a process called proteostasis. This protective system enables stressed neurons to survive, but it simultaneously restricts the production of new proteins needed for axon regeneration. Without active AHR, neurons shift their priorities, increasing protein production and activating biological pathways associated with growth and repair, partly through interactions with another factor called HIF-1α.
AHR was originally discovered for its role in detecting environmental toxins, but these findings reveal an expanded function within neurons. The protein appears to connect environmental responses with cellular processes that determine whether damaged axons can regenerate. The discovery has potential therapeutic implications, as several drugs designed to inhibit AHR are already in clinical trials for other conditions, creating opportunities to investigate similar approaches for nerve injuries.
Researchers acknowledge the work remains preliminary and additional studies are needed before clinical application. Future investigations will evaluate AHR inhibitors across different injury types, establish appropriate treatment timing and dosage, and assess effects on other cells involved in the injury response. The Mount Sinai team plans to explore both drug-based and gene-therapy approaches targeting AHR in neurons specifically, hoping to enhance regeneration and recovery following spinal cord injury, stroke, and other neurological conditions.
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