Researchers at the Icahn School of Medicine at Mount Sinai discovered a molecular mechanism that limits how effectively injured neurons regenerate damaged axons, according to a study published in the journal Nature. Scientists found that blocking a protein known as the aryl hydrocarbon receptor (AHR) improves nerve regeneration and functional recovery in experimental models, offering a potential path toward new treatments for peripheral nerve and spinal cord injuries.
Understanding the Molecular Brake on Axon Regeneration
Axons are long fibers that transmit signals between nerve cells across the central and peripheral nervous systems. When these structures face damage, recovery depends entirely on the neuron’s capacity to regrow them. In adult mammals, however, this regenerative ability is severely limited, which frequently results in permanent loss of movement or sensation following severe nerve trauma.
According to Hongyan Zou, MD, PhD, Professor of Neurosurgery and Neuroscience at the Icahn School of Medicine at Mount Sinai and senior author of the study, neurons face a difficult biological trade-off after injury. As Dr. Zou explained, AHR functions like a brake that shifts neurons toward managing cellular stress rather than rebuilding damaged connections.
Balancing Cellular Stress and Tissue Repair
Additional experiments revealed that active AHR signaling supports protein quality control, a cellular process called proteostasis. While this mechanism protects stressed cells, it simultaneously restricts the production of new proteins required to rebuild axons.
When researchers removed AHR or blocked its activity using targeted drugs, neurons shifted their priorities. The treated cells increased the production of new proteins and activated biological pathways associated with axon growth. This regenerative response relies heavily on another factor called HIF-1α, which controls genes responsible for metabolism and tissue repair.
Implications for Future Clinical Therapies
Originally identified as a sensor for environmental toxins and pollutants known as xenobiotics, AHR plays a critical internal role by integrating environmental signals with regenerative capacity, according to the study. Because several drugs that block AHR are already undergoing clinical trials for other medical conditions, researchers see a viable pathway toward testing these existing compounds on nerve and spinal cord injuries.
Despite these promising findings in mouse models, the research remains in early stages. Future investigations by the Mount Sinai team will examine how effectively AHR inhibitors perform across various types of neural damage, establish appropriate treatment timing and dosages, and evaluate how suppressing the protein affects other cells involved in the injury response.
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