# Project 3: Role of CTCF in HTLV-1 Replication and Transformation

> **NIH NIH P01** · OHIO STATE UNIVERSITY · 2021 · $373,491

## Abstract

PROJECT SUMMARY – PROJECT 3
Human T-cell leukemia virus type 1 (HTLV-1) is the cause of an aggressive, refractory T cell malignancy, adult
T-cell leukemia / lymphoma (ATL). The integrated proviral genome has a single binding site (BS) for the
chromatin insulator protein CTCF (CTCF-BS). The HTLV-1 CTCF-BS is located within the 3’portion of the
genome, downstream of 5’ proviral DNA that is generally methylated and bound by histones with markers of
inactive chromatin, and upstream of 3’ proviral DNA with generally unmethylated DNA and bound by histone
with markers of active chromatin. More than 50,000 CTCF-BS are also present in the human genome, which
can mediate DNA looping with the HTLV-1 CTCF-BS. In addition to, or as a result of its looping activity, CTCF
regulates epigenetic chromatin modifications and transcription. CTCF-BS in several DNA viruses are known to
be important for latency, reactivation from latency, and/or viral transcription. However, very little is known about
the role of CTCF in retroviruses, and there is only limited information about the epigenetic regulation of HTLV-
1. Our premise is that CTCF regulates establishment of HTLV-1 latency, and the rate of virus replication and
transformation in humanized mice. In Aim 1, we will use a Jurkat cell line model of HTLV-1 latency to examine
if the effect of CTCF on establishment of latency is mediated by preference for certain integration site
characteristics, and whether this affects the pattern of DNA methylation and H3K4me3 and H3K36me3
modifications of histones bound to the 5’ and 3’ proviral DNA. Aim 2 will examine the effect of mutation of the
CTCF-BS on HTLV-1 replication and transformation in humanized mice. For this purpose, we will use two
different humanized mouse models, one of which is a model of HTLV-induced lymphoma and the other a
model of HTLV-induced leukemia. Once again, we will examine whether specificity of proviral integration sites
affects virus replication and transformation, and epigenetic modifications. Aim 3 will examine the effect of
CRISPR/Cas9 editing of the CTCF-BS in ATL cell lines on DNA looping and their ability to proliferate in
immunodeficient mice. We will also determine if reconstitution of DNA looping independent of CTCF, through
use of defective Cas9 fused to looping protein Lim domain-binding protein 1 (LDB1) affects ATL cell
proliferation in immunodeficient mice. In summary, these studies will provide fundamental new information
about the mechanism whereby the CTCF insulator protein regulates HTLV-1 transcription, splicing, latency,
integration preference, immortalization, and tumorigenesis.

## Key facts

- **NIH application ID:** 10251303
- **Project number:** 5P01CA100730-17
- **Recipient organization:** OHIO STATE UNIVERSITY
- **Principal Investigator:** Lee Ratner
- **Activity code:** P01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $373,491
- **Award type:** 5
- **Project period:** 2003-04-21 → 2025-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10251303

## Citation

> US National Institutes of Health, RePORTER application 10251303, Project 3: Role of CTCF in HTLV-1 Replication and Transformation (5P01CA100730-17). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10251303. Licensed CC0.

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