SUMOylation in Neural Health and Disease: From Cellular Homeostasis to Neurodegeneration.

Neurodegenerative diseases (NDDs) represent a growing global health burden, particularly in aging populations. These disorders primarily affect neurons and are characterized by progressive neuronal dysfunction and loss within specific regions of the central nervous system. Major NDDs include Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, Huntington's disease, multiple sclerosis, and stroke. Although each disorder exhibits distinct genetic backgrounds and pathological protein aggregates, they share common pathogenic mechanisms, including chronic neuroinflammation, impaired autophagy and mitophagy, disrupted proteostasis, telomere instability, and epigenetic alterations. A hallmark feature across NDDs is the accumulation of misfolded proteins, leading to synaptic dysfunction and neuronal degeneration. Small ubiquitin-like modifiers (SUMOs) are a family of ∼100 amino acid proteins, including SUMO1 and the closely related SUMO2/3 isoforms. SUMOylation is a dynamic posttranslational modification that regulates protein function through the covalent attachment or removal of SUMO moieties. This reversible process is mediated by SUMO-specific E1 activating, E2 conjugating, and E3 ligating enzymes and is counterbalanced by SUMO/Sentrin-specific proteases. The SUMOylation status of target proteins depends on the tightly controlled balance between conjugation and deconjugation systems. Acting as a molecular switch, SUMOylation modulates diverse cellular processes such as DNA damage repair, RNA metabolism, transcriptional regulation, and protein quality control, all of which are essential for maintaining cellular homeostasis. Accumulating evidence links dysregulated SUMOylation to the pathogenesis of multiple neurological disorders, including polyglutamine and synucleinopathies. SUMOylation influences neuroinflammation, oxidative stress, protein aggregation, neuroangiogenesis, ischemic injury, and demyelination. This review highlights recent advances in understanding the role of SUMOylation in NDDs and explores its potential as a promising therapeutic target.