Histone Deacetylase 2 in Alzheimer's Disease: A Comprehensive Molecular Blueprint for Therapeutic Targeting

Alzheimer's disease (AD), which is known for causing cognitive decline and significant synaptic dysfunction, continues to pose a significant barrier to good health among the aging population worldwide. While there remain major knowledge gaps in the exact molecular framework of this complex and devastating disease, emerging evidence strongly implicates epigenetic dysregulation as having a major influence on the complexity of the various pathological processes, driving this debilitating disease. This comprehensive review meticulously delves into the critical and multifaceted role of histone deacetylase 2 (HDAC2) as a key player in actively driving the various neurotoxic processes closely connected to AD's characteristic pathological hallmarks and features. We extensively point out the diverse interconnected pathways via which dysregulated HDAC2 activity contributes to the initiation and progression of multiple intricate mechanisms responsible for the observed synaptic dysfunction, the marked accumulation of amyloid-beta (Aβ) plaques and the formation of neurofibrillary tau tangles. Furthermore, we explore the intricate interplay between the aberrant HDAC2 activity and resulting neuroinflammation and oxidative stress within the brain's microenvironment. Additionally, the review summarises the current developments towards HDAC inhibition, carefully identifying the existing limitations in this rapidly evolving field of research, and highlighting promising avenues and potential future directions for developing effective and demonstrably safe therapies. Finally, the approaches that can facilitate the selective modulation of this crucial epigenetic enzyme to combat the devastating effects of AD are suggested and elucidated.