# Dissecting the Role of RNA Pol II Pausing in Early Mammalian Development

> **NIH NIH F30** · WEILL MEDICAL COLL OF CORNELL UNIV · 2021 · $48,291

## Abstract

PROJECT SUMMARY/ABSTRACT
 Transcription regulation underlies the diversity of cell types and functions. The process of transcription itself
has multiple steps that may be regulated separately. Promoter-proximal RNA Pol II pausing has recently been
described as a widespread rate-limiting step of transcription and a possible point of gene regulation. Studies
disrupting the critical pausing factor Negative elongation factor-B (Nelf-b) in mouse and mouse embryonic stem
cells (mES) highlighted its essential role in development and a cross-talk with FGF/ERK signaling transduction.
However, it is unclear what role pausing plays in mammalian development. Furthermore, it is unclear how
pausing may affect specific targets of FGF/ERK signaling, and whether this cross-talk is relevant in vivo.
The long-term goal of this proposal is to establish a molecular understanding of how gene regulation can be
achieved at the level of promoter-proximal pausing during transcription. The objective of the present proposal is
to mechanistically determine the role of pausing during epiblast pluripotency transitions in early mammalian
development. This objective will be achieved by a detailed phenotypic and transcriptomic analysis of Nelf-b-/-
embryos at several early developmental stages to analyze pluripotency transitions (Aim 1). To expand on these
results and interrogate pausing at a high molecular and temporal resolution, a Nelf-b-degron mES cell line has
been established to test the immediate and direct effects of pausing-loss in mES cells under different signaling
conditions. I will utilize nascent RNA-seq techniques and directed differentiation approaches to build a
mechanistic link between pausing, FGF/ERK transcriptional activation, and pluripotency transitions in embryos
and mES cells (Aim 2). My central hypothesis is that pausing is required for epiblast pluripotency
transitions in mouse development via direct regulation of FGF/ERK transcriptional targets.
 The expected outcome of this project is to uncover the mechanistic link between pausing and signal
transduction, explain the role of pausing in mammalian development. It promises to yield novel insights into gene
regulation at the pausing level. The link between pausing and signaling is of high importance to other biological
contexts considering the prevalence of pausing and necessity of signal transduction to perform fundamental
cellular functions beyond responses to FGF/ERK in development. Furthermore, given that FGF/ERK signaling
is amongst the top dysregulated pathways in developmental diseases and malignancies, insights into the
molecular mechanisms of this pathway will yield novel insights to therapeutically target it.

## Key facts

- **NIH application ID:** 10151189
- **Project number:** 1F30HD103398-01A1
- **Recipient organization:** WEILL MEDICAL COLL OF CORNELL UNIV
- **Principal Investigator:** Abderhman Anees Abuhashem
- **Activity code:** F30 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $48,291
- **Award type:** 1
- **Project period:** 2021-04-01 → 2025-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10151189

## Citation

> US National Institutes of Health, RePORTER application 10151189, Dissecting the Role of RNA Pol II Pausing in Early Mammalian Development (1F30HD103398-01A1). Retrieved via AI Analytics 2026-05-21 from https://api.ai-analytics.org/grant/nih/10151189. Licensed CC0.

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