# Transcriptional control of gut epithelial homeostasis and regeneration

> **NIH NIH R01** · DANA-FARBER CANCER INST · 2020 · $439,177

## Abstract

Project Description
 Inflammation, cancer, and other common disorders of the digestive tract reflect dysfunction in the
dynamics of intestinal stem (ISC) and other crypt cells. Improved treatments require a better understanding
of how Lgr5+ ISC, progenitor, and differentiated cell states may be promoted or disfavored. Recent findings
substantially revise the traditional view that movement from ISC  intestinal bipotential progenitor (IBP) 
transit-amplifying (TA) cells is strictly linear and unidirectional. Instead, crypts appear to be highly dynamic
units, where cells interconvert with surprising ease and various dedifferentiating progenitors are the main
source of crypt regeneration after ISC injury. One gene particularly implicated in ISC functions encodes
the Wnt-dependent transcription factor (TF) ASCL2. In the last funding period, we examined chromatin
states critically in diverse resting crypt populations and in cells captured in the act of dedifferentiating into
ISC; those findings made notable mechanistic contributions toward the emerging view of crypt dynamics in
relation to chromatin states. To build on the advances, we engineered a new mouse Ascl2 allele to flag its
expression with a fluorescent label, identify binding sites by epitope-tagged chromatin immunoprecipitation
(ChIP), and delete the gene at will. Contrary to a published report, we find that Ascl2 is dispensable for
resting ISC function. It is, however, essential (a) for crypts to replenish Lgr5+ ISC when the native pool is
damaged, and (b) for cells with constitutive Wnt activity (Apc-/-) to form sizable tumors. Moreover, both
Ascl2-/- and Ascl2+/- ISC differentiate prematurely into IBP, suggesting that ASCL2 levels dictate cell exit
from the ISC compartment. These animal models and preliminary data provide the background and tools to
ask fundamental mechanistic questions about the determinants of ISC vs. IBP vs. TA identity. Aim 1
examines wild-type and Ascl2-/- ISC and isolated regenerating crypt cells using state-of-the-art epigenome
methods to identify crucial, ASCL2-dependent steps that favor the ISC state in native Lgr5+ and
dedifferentiating cells. We will also ask which crypt populations can dedifferentiate and, in organoid
cultures, which extrinsic signals promote rapid ASCL2-dependent crypt regeneration. Aim 2 tackles the
problem that dedifferentiation of tumor cells limits the potential of ablating tumor-initiating (TIC, `cancer
stem') cells as a treatment for cancer. We will test the hypotheses that ASCL2 drives distinct transcriptional
programs in tumor and normal ISC, and that it is required to maintain tumors by dedifferentiation when TIC
are killed. These studies could have important future clinical applications. Aim 3 tests the hypothesis that
Lgr5+ cells in the crypt base are intrinsically poised at the junction between ISC and IBP states, and that
ASCL2 levels determine ISC vs IBP identity. This original and cohesive investigation of labile crypt cell
s...

## Key facts

- **NIH application ID:** 9895727
- **Project number:** 5R01DK081113-10
- **Recipient organization:** DANA-FARBER CANCER INST
- **Principal Investigator:** Ramesh A Shivdasani
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $439,177
- **Award type:** 5
- **Project period:** 2009-09-01 → 2023-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9895727

## Citation

> US National Institutes of Health, RePORTER application 9895727, Transcriptional control of gut epithelial homeostasis and regeneration (5R01DK081113-10). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/9895727. Licensed CC0.

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