# Sex divergence and cell specificity of age-related hippocampal DNA modifications

> **NIH NIH R01** · OKLAHOMA MEDICAL RESEARCH FOUNDATION · 2021 · $554,739

## Abstract

Abstract
Epigenetic processes in the central nervous system may play a mechanistic role in susceptibility to and
progression of cognitive decline and age-related neurodegenerative diseases, such as Alzheimer's. DNA
modifications, principally cytosine base methylation and hydroxymethylation (mC and hmC respectively), are
fundamental regulators of DNA accessibility and gene regulation/expression with differential effects on gene
expression depending on the modification (mC/hmC), context CG/non-CG (also known as CH), and genomic
location. A barrier to progress in understanding the role of epigenetic mechanisms in brain aging and DNA
modifications in particular, has been the lack of quantitatively accurate, genome-wide data in specific cell
types. Without the knowledge of the specific genomic locations of altered modifications with aging it is
impossible to design well-rationalized, mechanistic studies that unravel the functional effects of epigenetic
reconfiguration. Therefore, the critical next step for the field is to generate this genome-wide data of mC and
hmC in CG and CH contexts in specific cell types from both sexes across the lifespan. To address this critical
issue we have developed cell-type specific, tamoxifen-inducible Cre, transgenic NuTRAP models to allow
isolation of nucleic acids (DNA & RNA) from microglia, astrocytes, and neurons. In Aim 1, cell type-specific
hippocampal changes in mC/hmC with aging will be examined by whole genome oxidative bisulfite sequencing
(WGoxBS) in microglia, astrocytes, and neurons. Paired epigenomic and transcriptomic data from the same
animals will be used to: 1) assess aging with `epigenetic clocks' in a cell-type specific fashion, 2) determine the
role of altered modification patterns in age-related changes in gene expression, 3) determine enrichment of
differential modifications in regulatory regions of the genome, and 4) identify genomic loci for epigenome
editing. In prior studies we have determined that age-related DNA modification changes can be prevented by
caloric restriction. In Aim 2 we will test whether heterochronic parabiosis can reverse age-related changes
once extant in the same Cre-inducible, NuTRAP models. Using a unique database of all publicly available,
annotated human methylation data we will validate aspects of our findings in humans. In Aim 3 we will
examine the targeting mechanisms that direct changes in mC/hmC to specific genomic regions. These studies
will allow the determination of critical genomic regions with altered DNA modification patterns that can be
manipulated in future interventional studies. The ultimate goal of the research is to develop clinical
interventions that target the epigenome to maintain brain function with aging and prevent age-related
neurodegeneration.

## Key facts

- **NIH application ID:** 10147843
- **Project number:** 5R01AG059430-03
- **Recipient organization:** OKLAHOMA MEDICAL RESEARCH FOUNDATION
- **Principal Investigator:** WILLARD M FREEMAN
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $554,739
- **Award type:** 5
- **Project period:** 2019-07-01 → 2024-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10147843

## Citation

> US National Institutes of Health, RePORTER application 10147843, Sex divergence and cell specificity of age-related hippocampal DNA modifications (5R01AG059430-03). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10147843. Licensed CC0.

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