# Novel pathways that regulate DNA double-strand break repair events in mammalian cells

> **NIH NIH R35** · WEILL MEDICAL COLL OF CORNELL UNIV · 2024 · $423,750

## Abstract

Summary Abstract
 The overall vision for our research is to discover novel mechanisms by which histone and non-histone
proteins on DNA, i.e. chromatin, regulate genomic processes and aging. In particular, we strive to integrate
different fields, such as the role of chromatin in genome stability and the role of chromatin in aging. Using a
combination of biochemistry, structural biology, molecular genetics in budding yeast, tissue culture and
genome-wide approaches, we have discovered that chromatin is disassembled and reassembled during not
only gene expression and DNA replication but also during DNA double-strand break repair. We have
revealed the mechanistic bases for these events and their key impact on these genomic processes. In more
recent years, we have expanded the questions that we address beyond chromatin – for example uncovering
novel mechanistic bases of aging and discovering new ways to extend lifespan. Similarly, inspired by our
recent finding that chromatin structure reduces the processing of DNA double-strand breaks to single-strand
DNA (termed DNA end resection), we have devised innovative CRISPR/Cas9 gRNA library screening
approaches to identify novel activities that regulate DNA end resection during DNA double-strand repair.
Most of the cells in the human body are in G0/G1-phase and it is critical that excessive DNA end resection
does not occur in these cells. If it were to occur, it would block DNA repair by the only pathway that is used to
repair DNA double-strand breaks in G0/G1-phase cells, namely non-homologous end joining (NHEJ), and it
would result in translocations and deletions from the ensuing homology-mediated repair. Indeed, the extent
of DNA end resection is the critical decision point in the choice between using the NHEJ or homologous
recombination (HR) pathway for repairing DNA double-strand breaks. We propose that mechanisms must be
in place that limit excessive DNA end resection in G0/G1-phase cells to prevent HR, yet enable sufficient DNA
end processing of un-ligatable DNA ends to allow NHEJ-mediated repair. The proteins and pathways that
regulate the extent of DNA end resection in G0/G1-phase cells are currently unknown. Thus, a major goal of
this program is to discover the machinery and mechanisms that regulate DNA end resection in G0/G1-phase
cells. We are uniquely positioned to do this, based on our expertise, novel genetic screening approach and
compelling preliminary data.
 Another critical, yet poorly understood, aspect of genome maintenance is how gene expression is
“shut-off” in the vicinity of a DNA lesion to prevent collisions between the transcription and DNA repair
machinery. Similarly, it is crucial that transcription is restarting after DNA double-strand break repair, but the
mechanism is unknown. We have recently discovered some of the proteins involved using our novel assays
and genetic screens, so the second major goal of this program is to discover the fundamental mechanisms of
transcriptiona...

## Key facts

- **NIH application ID:** 10774237
- **Project number:** 5R35GM139816-04
- **Recipient organization:** WEILL MEDICAL COLL OF CORNELL UNIV
- **Principal Investigator:** Jessica K Tyler
- **Activity code:** R35 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $423,750
- **Award type:** 5
- **Project period:** 2021-03-01 → 2026-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10774237

## Citation

> US National Institutes of Health, RePORTER application 10774237, Novel pathways that regulate DNA double-strand break repair events in mammalian cells (5R35GM139816-04). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10774237. Licensed CC0.

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