Semax Peptide Targets μ-Opioid Receptor, Promotes Functional Recovery After Spinal Cord Injury

A recent study reveals the molecular mechanism by which the synthetic heptapeptide Semax precisely regulates the μ-opioid receptor to promote functional recovery after spinal cord injury, providing a new target for clinical treatment.

A study recently published in the British Journal of Pharmacology has uncovered the molecular mechanism through which the synthetic heptapeptide Semax, by targeting the μ-opioid receptor Oprm1 and regulating the ubiquitin-specific protease USP18, promotes the deubiquitination of the FTO protein, significantly improving functional recovery in female mice after spinal cord injury.

Addressing the issue of increased lysosomal membrane permeabilization following spinal cord injury, which leads to neuronal death, the research discovered that Semax peptide, by activating the USP18-FTO axis, effectively inhibits lysosomal membrane rupture-induced pyroptosis.

01 Research Background: The Challenge of Spinal Cord Injury Treatment

Neuronal death caused by increased Lysosomal Membrane Permeabilization after Spinal Cord Injury is a major obstacle affecting patient recovery.

Currently, treatment strategies targeting the ubiquitination pathway regulation after SCI remain exploratory, and scientists have been searching for new therapeutic targets that can precisely modulate this pathway.

In this context, a domestic research team turned their attention to the Semax peptide, a synthetic heptapeptide containing an ACTH(4-7) fragment and a C-terminal Pro-Gly-Pro tripeptide.

Previous studies indicated that Semax peptide possesses neuroprotective potential, but its specific mechanism of action in spinal cord injury repair had not been fully elucidated.

02 Research Findings: Semax as a "Molecular Switch"

Through animal experiments and cell models, the research team found that Semax can precisely regulate the μ-opioid receptor like a "molecular switch", subsequently activating the ubiquitin-specific protease USP18.

This cascade reaction ultimately leads to the deubiquitination of the Fat Mass and Obesity-associated protein, effectively inhibiting lysosomal membrane rupture-induced pyroptosis.

In a T9-T10 segment spinal cord injury model using female C57BL/6 mice, scientists observed that Semax treatment significantly improved motor function recovery.

The study employed a multi-dimensional validation strategy, assessing motor function recovery via footprint analysis and Basso Mouse Scale scores, combined with Western blot and transmission electron microscopy to observe molecular changes.

03 Mechanism Explained: The OPRM1-USP18-FTO Axis

RNA sequencing identified USP18 as the key "regulator" in Semax's mechanism of action, while molecular docking experiments confirmed the binding characteristics between Semax and the μ-opioid receptor in a manner resembling a "lock and key" fit.

These findings not only explain the molecular mechanism by which Semax exerts its neuroprotective effects through the OPRM1-USP18-FTO axis, but also provide crucial theoretical basis for clinical translation.

The research indicates that Semax enhances the stability of FTO protein within cells by promoting its deubiquitination, thereby exerting its neuroprotective effect.

After Semax binds to the μ-opioid receptor, it triggers a series of intracellular signal transduction events, ultimately improving the neuronal survival environment.

04 Medical Significance: Providing a New Therapeutic Target

This research provides a new potential target for the clinical treatment of spinal cord injury, namely the OPRM1-USP18-FTO signaling axis.

Drug development targeting this pathway could bring new treatment hope for patients with spinal cord injuries.

Simultaneously, the study reveals the important role of the deubiquitination process in neuroprotection, offering a new perspective for understanding other neurological injury mechanisms.

Unlike traditional neurotrophic factor strategies, this research promotes neural recovery by regulating protein stability, representing a novel therapeutic approach.

With a deeper understanding of the mechanism of action of the Semax peptide, scientists anticipate further exploration in more neurological injury models.

The discovery of the OPRM1-USP18-FTO axis not only provides a new direction for spinal cord injury treatment but also opens a new window for understanding the self-repair capabilities of the nervous system.

In the future, drug development based on this mechanism holds promise for bringing new hope to patients with neurological injuries.