# Erythroid Self-Renewal

> **NIH NIH R01** · UNIVERSITY OF ROCHESTER · 2024 · $677,600

## Abstract

Self-renewal is the process by which a cell divides to generate daughter cells that have the same
developmental potential as the parent cell. The overall goal of our collaborative research project is to gain a
mechanistic understanding of erythroid progenitor (EP) self-renewal, both in vitro and in vivo. Red blood cells
(RBCs) make up more than 80% of all cells in the human body, but have a limited lifespan, necessitating a
massively expansive and exquisitely responsive production system. This production is regulated predominantly
at the late progenitor phase of erythropoiesis, since downstream erythroid precursors undergo a fixed number
of maturational cell divisions. In vitro, erythroid progenitor self-renewal is limited, which is a major stumbling
block to production of specialized units of blood. The Palis lab discovered that erythroblasts derived from the
yolk sac of murine embryos were capable of essentially unlimited self-renewal. These cells had increased
expression of the Polychrome Repressive Complex (PRC1) members Bmi1 and Ring1b, as well as cholesterol
metabolism genes. Importantly, overexpression of BMI1, a chromatin modulator normally expressed in
erythroid progenitors, can also expand human erythroid cells in vitro, termed BMI1-induced self-renewing
erythroblasts (iSREs). Collaborative studies with the Steiner lab provide evidence that BMI1 alters the self-
renewal capacity of human erythroblasts both through known (e.g., Ink/Arf locus), and novel (e.g., cholesterol
homeostasis) pathways. Our data further suggest that BMI alters the activity of RING1B, which
monoubiquitinates histone H2A lysine 119, and also has essential roles in regulating higher order chromatin
interactions. In Aim 1 we will test the hypothesis that BMI1/Ring1b regulate human SRE self-renewal through
epigenetic control of transcription and cholesterol homeostasis. Expansion of erythroid progenitors is essential
to maintain steady state erythropoiesis and for the response to acute anemic or hypoxic stress. In preliminary
studies we have defined 4 progressive stages of murine erythroid progenitors, termed EP1 to EP4, analogous
to those recently defined in humans, and determined that late-stage EP3/4 progenitors preferentially expand in
the marrow of mice in response to acute anemia. In Aim 2 we will test the hypothesis that Bmi1/Ring1b and its
downstream targets regulate the expansion of late-stage (EP3/EP4) erythroid progenitors both at steady-state
and in response to acute anemia. Together, these studies will provide mechanistic understanding of erythroid
progenitor self-renewal and bring a renewable source of human erythroblasts closer to the clinic to meet
specialized transfusion needs.

## Key facts

- **NIH application ID:** 10823927
- **Project number:** 1R01HL172500-01
- **Recipient organization:** UNIVERSITY OF ROCHESTER
- **Principal Investigator:** James Palis
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $677,600
- **Award type:** 1
- **Project period:** 2024-08-01 → 2028-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10823927

## Citation

> US National Institutes of Health, RePORTER application 10823927, Erythroid Self-Renewal (1R01HL172500-01). Retrieved via AI Analytics 2026-06-12 from https://api.ai-analytics.org/grant/nih/10823927. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*