Post-Translational Modifications in Traumatic Brain Injury: Decoding the Proteomic Landscape and Molecular Mechanisms of Secondary Injury.

Traumatic brain injury (TBI) initiates a complex secondary injury cascade that significantly contributes to long-term neurological deficits, with post-translational modifications (PTMs) emerging as pivotal molecular regulators of this process. Unlike primary mechanical damage, secondary injury evolves over hours to years and involves intricate proteomic alterations that changes in gene expression alone cannot fully explain. PTMs-including phosphorylation, ubiquitination, acetylation, SUMOylation, glycosylation, and emerging modifications such as succinylation, lactylation, and nitrosylation-serve as dynamic molecular switches that fine-tune protein function, stability, localization, and interactions in response to TBI-induced stressors. These modifications play dual roles: they can either promote neuroprotection and recovery or drive pathological processes such as neuronal cell death (via apoptosis, necroptosis, and ferroptosis), neuroinflammation through glial activation and inflammasome signaling, blood-brain barrier disruption, mitochondrial dysfunction, and impaired synaptic plasticity. Critically, extensive crosstalk exists among different PTM pathways-such as the interplay between phosphorylation and ubiquitination in protein degradation or the competitive balance between acetylation and SUMOylation-that collectively shape cellular fate after injury. This nuanced regulatory network presents both challenges and opportunities for therapeutic intervention. Targeting PTM-related enzymes, including kinases, phosphatases, E3 ligases, and histone deacetylases, has shown promise in preclinical models, while novel strategies like Proteolysis-Targeting Chimeras (PROTACs) and repurposed drugs (e.g., metformin, resveratrol) offer innovative avenues for modulating the PTM landscape. Advances in high-throughput proteomics and mass spectrometry are enabling the mapping of TBI-specific PTM signatures across spatiotemporal phases, facilitating the identification of pro-survival versus pro-death modification thresholds. Despite hurdles in clinical translation-such as blood-brain barrier penetration and off-target effects-the growing understanding of PTM dynamics underscores their potential as both biomarkers and therapeutic targets. Future TBI management may thus rely on precision medicine approaches that integrate multi-PTM profiling to guide combination therapies aimed at tipping the balance toward neural repair and functional recovery.