Karisetty, B. C. | bioRxiv Science

bioRxiv2021

Chromatin and transcriptomic profiling uncover dysregulation of the Tip60 HAT/HDAC2 epigenomic landscape in the neurodegenerative brain

Disruption of histone acetylation mediated gene control is a critical step in Alzheimers Disease (AD), yet chromatin analysis of antagonistic histone acetyltransferases (HATs) and histone deacetylases (HDACs) causing these alterations remains uncharacterized. We report the first Tip60 HAT versus HDAC2 chromatin and transcriptional profiling study in Drosophila brains that model early human AD. We find Tip60 and HDAC2 predominantly recruited to identical neuronal genes. Moreover, AD brains exhibit robust genome-wide early alterations that include enhanced HDAC2 and reduced Tip60 binding and transcriptional dysregulation. Orthologous human genes to co-Tip60/HDAC2 Drosophila neural targets exhibit conserved disruption patterns in AD patient hippocampi. Notably, we discovered distinct transcription factor (TF) binding sites within Tip60/HDAC2 co-peaks in neuronal genes, implicating them in co-enzyme recruitment. Increased Tip60 protects against transcriptional dysregulation and enhanced HDAC2 enrichment genome-wide. We advocate Tip60 HAT/HDAC2 mediated epigenetic neuronal gene disruption as a genome-wide initial causal event in AD.

genomics↗

bioRxiv2020

Transcriptome analysis uncovers distinct modes of epigenetic gene changes in early versus late stages of amyloid-β induced Alzheimer's disease pathology

Alzheimers disease (AD) is an age-related neurodegenerative disorder hallmarked by amyloid-{beta} (A{beta}) plaque accumulation, neuronal cell death, and cognitive deficits that worsen during disease progression. Histone acetylation dysregulation, caused by an imbalance between reduced histone acetyltransferases (HAT) Tip60 and increased histone deacetylase 2 (HDAC2) levels, can directly contribute to AD pathology. However, whether such AD-associated neuroepigenetic alterations occur in response to A{beta} peptide production and can be protected against by increasing Tip60 levels over the course of neurodegenerative progression remains unknown. Here we profile Tip60 HAT/HDAC2 dynamics and transcriptome-wide changes across early and late stage AD pathology in the Drosophila brain produced solely by human amyloid-{beta}42. We show that early A{beta}42 induction leads to disruption of Tip60 HAT/HDAC2 balance during early neurodegenerative stages preceding A{beta} plaque accumulation that persists into late AD stages. Correlative transcriptome-wide studies reveal alterations in biological processes we classified as transient (early-stage only), late-onset (late-stage only), and constant (both). Increasing Tip60 HAT levels in the A{beta}42 fly brain protects against AD functional pathologies that include A{beta} plaque accumulation, neural cell death, cognitive deficits, and shorter life-span. Strikingly, Tip60 protects against A{beta}42-induced transcriptomic alterations via distinct mechanisms during early and late stages of neurodegeneration. Our findings reveal distinct modes of neuroepigenetic gene changes and Tip60 neuroprotection in early versus late stages in AD that can serve as early biomarkers for AD, and support the therapeutic potential of Tip60 over the course of AD progression.

neuroscience↗