# Defining the role of DOT1L in chromocenter stabilization pre- and post-fertilization

> **NIH NIH R21** · YALE UNIVERSITY · 2023 · $460,625

## Abstract

PROJECT SUMMARY
Dramatic restructuring of chromatin is an essential event preceding and immediately following fertilization. The
developing sperm nucleus undergoes extreme compaction, and this hypercompact genetic material is rapidly,
aggressively repackaged into a chromatinized state soon after entering the oocyte. Failure to enact these
changes leads to nuclear disorganization and produces inviable embryos. Chromocenters are large, dense
nuclear structures that coordinate reprogramming of repressive heterochromatin during these transitions, and
chromocenter integrity is important for fertility. Despite its importance, a major unsolved problem is what
signal or signals trigger chromocenter disassembly in developing sperm heads and stimulate
chromocenter reassembly in embryos. The overall objective of this project is to define the molecular pathways
that govern chromocenter restructuring before and after the events of fertilization. The central hypothesis is
that the same chromatin regulator, DOT1L, controls both chromocenter disassembly before fertilization
and chromocenter reassembly after fertilization by stimulating transcription of pericentromeric major
satellite repeats. This hypothesis is supported by preliminary data indicating that DOT1L has a specialized role
in promoting expression of major satellite repeat elements and that this function is important for formation of
chromocenters. Preliminary studies also demonstrated that DOT1L is required for male fertility, and that it is
active in chromocenters and required for nuclear reprogramming and condensation in the late stages of sperm
development, and that its activity is required for preimplantation embryogenesis. The hypothesis will be tested
in two Specific Aims: the first Aim will test the contribution of DOT1L to chromocenter disassembly during sperm
nuclear condensation, and the second Aim will determine how DOT1L regulates chromocenter assembly in
early embryos. This project is innovative for its conceptual advance implicating a unifying regulatory factor in
control of heterochromatin disassembly and reassembly before and after fertilization, its exploration of a novel
mechanism for transmission of epigenetic information across generations, its establishment of a new molecular
and biological function for DOT1L, and its use of precision heterochromatin visualization techniques in
preimplantation embryos. This work is expected to reveal a fundamental missing link governing the dramatic
heterochromatin reprogramming that occurs both before and after fertilization, advancing understanding of
genome regulation during gamete and embryo development and revealing a new relationship between paternal
chromatin and the epigenetic state of the embryo.

## Key facts

- **NIH application ID:** 10739438
- **Project number:** 1R21HD110843-01A1
- **Recipient organization:** YALE UNIVERSITY
- **Principal Investigator:** Bluma J Lesch
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2023
- **Award amount:** $460,625
- **Award type:** 1
- **Project period:** 2023-08-01 → 2025-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10739438

## Citation

> US National Institutes of Health, RePORTER application 10739438, Defining the role of DOT1L in chromocenter stabilization pre- and post-fertilization (1R21HD110843-01A1). Retrieved via AI Analytics 2026-06-01 from https://api.ai-analytics.org/grant/nih/10739438. Licensed CC0.

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