# Development and Application of a Novel Method to Study Histone Inheritance in Asymmetrically Dividing Cells

> **NIH NIH F32** · JOHNS HOPKINS UNIVERSITY · 2024 · $78,892

## Abstract

Proper development depends on asymmetric cell division (ACD), a process by which dividing stem cells
produce a renewed stem cell and a differentiating cell. Many intrinsic and extrinsic factors guiding ACD have
been found and characterized. Yet, the contribution of chromatin to cell-fate determination is poorly
understood. Previously, our lab discovered asymmetries in histone and histone post-translational modification
(hPTM) inheritance in Drosophila male germ cells. Further dissection of this process revealed it functions and
is regulated in three-steps: 1) histone asymmetry is established during S-phase; 2) histone asymmetry is
distinguished during M-phase; 3) the readout of the inherited asymmetric histones guides cell cycle
progression following mitotic exit. Interestingly, disruption of these asymmetries results in both stem cell loss
and overproliferation phenotypes, suggesting that asymmetric histone inheritance is an essential process in
tissue health. Further, deterioration of this process may be common among diseases including age-related
tissue degeneration and cancer. I hypothesize that asymmetric histone inheritance is a general mechanism
that plays a crucial role in stem cell homeostasis and cell-fate determination during development. However, our
ability to track histones and hPTMs at specific loci within single cells is severely limited at this time. Thus, we
are in urgent need of new tools to study the roles and consequences of asymmetric histone inheritance in
development, stem cell homeostasis, and cell-fate determination. In this proposal, I will 1) broaden our
understanding of pervasiveness, roles, and patterns of histone inheritance in asymmetrically dividing cells and
2) develop a novel method for labeling non-repetitive loci to track epigenomic features.
 First, I will express histones tagged with the photoconvertible Dendra2 in Drosophila neuronal stem cell
lineages. Neuroblasts (NBs), their progenies ganglion mother cells (GMCs), and transit-amplifying intermediate
neuronal progenitors (INPs) are a well-studied stem cell model system. Following 405nm light induced
photoconversion, I will observe the inheritance patterns of old (red) versus new (green) histones in type I and II
NBs. These studies will 1) expand our knowledge on histone inheritance in ACD, and 2) reveal whether histone
inheritance patterns change as asymmetrically dividing cells age and lose potency (e.g. INPs).
 Tracking epigenomic information at specific genomic locations has traditionally been performed using
FISH. However, the heat denaturation required for FISH is either partially or completely incompatible with
detection of DNA-associated proteins. To overcome this limitation, I will adapt Oligopaint technologies to
design guide RNA libraries for tethering dCas9 to specific, non-repetitive loci. This will allow me to track
histone and hPTM inheritance patterns at specific genomic loci with single-cell resolution.
 These works will both enhance our u...

## Key facts

- **NIH application ID:** 10909202
- **Project number:** 5F32AG076216-03
- **Recipient organization:** JOHNS HOPKINS UNIVERSITY
- **Principal Investigator:** Jason Thomas Palladino
- **Activity code:** F32 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $78,892
- **Award type:** 5
- **Project period:** 2022-09-01 → 2025-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10909202

## Citation

> US National Institutes of Health, RePORTER application 10909202, Development and Application of a Novel Method to Study Histone Inheritance in Asymmetrically Dividing Cells (5F32AG076216-03). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10909202. Licensed CC0.

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