# Project 3 Control of Erythroid Differentiation by Transcription Elongation, Leonard I. Zon

> **NIH NIH P01** · BOSTON CHILDREN'S HOSPITAL · 2021 · $433,420

## Abstract

Abstract
Hematopoiesis is regulated by transcription factors that activate lineage-specific programs. Transcription
initiates, and pauses; the pause is then released, a process guided by cdk9, a kinase that phosphorylates Pol
II. TIF1γ is a chromatin factor that is mutated in the bloodless moonshine zebrafish mutant: we have
demonstrated that a mouse knockout of TIF1γ has decreased marrow erythropoiesis, no B cells, and
expanded myelopoiesis. Using chemical genetics in the zebrafish, we found that clofibrate and leflunomide,
activators of the nuclear receptors PPARα and SXR, rescue blood development in the moonshine mutant. We
now propose to examine the genetic program that establishes this rescue, including an evaluation of gene
expression in the rescued mutants. We will purify the PPARα and SXR complexes by affinity tagging and
mass spectroscopy, and use zebrafish genetics to establish the downstream pathways that affect the rescue.
A prior genetic screen for moonshine demonstrated rescue with mutations in the PAF1 complex or in spt5, both
of which regulate transcription elongation. The paf1 zebrafish mutant is rescued by mating to a cdk9 mutant,
which suggests that some transcripts hyper-elongate in the paf1 mutant. A recent large-scale knockdown
screen for chromatin factors that are required for erythropoiesis during zebrafish development revealed that
antisense morpholinos to 6 chromatin factors reduce red blood cell development, and knockdown of 9
chromatin factors increases erythropoiesis: we will assess whether these chromatin factor genes can be
rescued by mutations in PAF1, spt5, or cdk9. We will also determine whether activators of specific nuclear
hormone pathways can rescue the chromatin factor mutants. Our study will provide a comprehensive analysis
of chromatin factors and how they regulate transcription elongation, and will offer the clinical opportunity to
modify these pathways for the treatment of blood diseases such as sickle cell anemia and thalassemia.
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## Key facts

- **NIH application ID:** 10146451
- **Project number:** 5P01HL032262-39
- **Recipient organization:** BOSTON CHILDREN'S HOSPITAL
- **Principal Investigator:** LEONARD Ira ZON
- **Activity code:** P01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $433,420
- **Award type:** 5
- **Project period:** 1997-07-01 → 2022-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10146451

## Citation

> US National Institutes of Health, RePORTER application 10146451, Project 3 Control of Erythroid Differentiation by Transcription Elongation, Leonard I. Zon (5P01HL032262-39). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10146451. Licensed CC0.

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