Epigenetic control of microglial mitochondrial immunity by KAT7 drives Alzheimer's disease pathogenesis.

Mitochondrial DNA (mtDNA)-driven innate immune signaling sustains chronic neuroinflammation in neurological diseases such as Alzheimer's disease (AD), yet how this pathway is regulated in microglia remains poorly understood. Here, we identify the histone acetyltransferase KAT7 (HBO1) as a central epigenetic regulator that links chromatin remodeling to mitochondrial immune activation. KAT7 and its histone mark H3K14ac are elevated in microglia from 5×FAD mice and human AD brains. Integrative transcriptomic and epigenomic analyses reveal that KAT7 activates transcription of cytidine/uridine monophosphate kinase 2 (Cmpk2), a mitochondrial kinase essential for mtDNA synthesis. Loss of KAT7 reduces Cmpk2 expression, impairs mtDNA replication and release, and consequently suppresses cyclic guanosine monophosphate-AMP synthase (cGAS)-stimulator of interferon genes (STING) and NLRP3 signaling. Importantly, both microglia-specific deletion and pharmacological inhibition of KAT7 mitigate cytosolic mtDNA-induced neuroinflammation, decrease β-amyloid burden, restore synaptic plasticity, and improve cognitive function in 5×FAD mice. Together, these findings uncover an epigenetic-mitochondrial axis sustaining microglial pathogenicity and establish KAT7 as a potential therapeutic target for AD.