HDACs in the Brain: From Chromatin Remodeling to Neurodegenerative Disease.

Histone deacetylases (HDACs) are key epigenetic regulators that influence chromatin remodeling, gene expression, and cellular plasticity in the central nervous system (CNS). This review provides a comprehensive overview of the classification and functional diversity of HDACs, with particular emphasis on their roles in neural progenitor cells, mature neurons, and glial populations. In neural stem and progenitor cells, HDACs modulate neurogenesis, fate specification, and lineage commitment. In differentiated neurons, HDACs govern synaptic plasticity, memory formation, and survival. In glial cells, including astrocytes and microglia, HDACs orchestrate inflammatory responses, redox balance, and metabolic adaptations. We further examine the dysregulation of HDAC expression and activity in major neurodegenerative diseases, including Alzheimer's disease and Parkinson's disease. Evidence from human post-mortem brain studies reveals region- and isoform-specific alterations in HDAC expression, which are closely associated with cognitive decline, mitochondrial dysfunction, and neuroinflammation. Preclinical studies support the use of HDAC inhibitors (HDACi) as neuroprotective agents, capable of restoring acetylation homeostasis, reducing neuroinflammation, and improving neuronal function. Given the relevance of HDACi, we summarize current clinical studies assessing the safety of these compounds in the context of tumor biology, as well as their potential future applications in neurodegenerative diseases. Together, this review underscores the dual significance of HDACs as biomarkers and therapeutic targets in the context of CNS disorders.