# Novel Notch regulation in KSHV reactivation

> **NIH NIH R21** · RBHS-NEW JERSEY MEDICAL SCHOOL · 2021 · $196,250

## Abstract

Project Description/Abstract
 Defining the molecular interactions between a virus and its host that regulate gene-specific transactivation
has been essential to understanding DNA virus persistence and replication. The Kaposi’s sarcoma-associated
Herpesivrus Rta protein is necessary and sufficient for the virus to emerge from latency and replicate (lytic
reactivation). Rta interacts directly with the cellular protein called RBP-Jk, which is also required for lytic reacti-
vation. RBP-Jk normally specifies the genes that will be activated by the cellular Notch signal transduction
pathway by binding sequence specifically to DNA. In this fashion, RBP-Jk serves as a “landing pad” for the
activated Notch receptor (Notch intracellular domain (NICD1)). KSHV Rta stimulates DNA binding of RBP-Jk
during viral reactivation, a mechanism that is fundamentally different from the canonical mechanism established
for other RBP-Jk-activating proteins, namely NICD1 and Epstein-Barr Virus (EBV) EBNA-2. Indeed, NICD1 is
unable to stimulate complete viral reactivation, supporting a promoter-specific mechanism for controlling its
activity in KSHV infected cells. Recent data suggest that DNA binding of RBP-Jk is regulated both positively
and negatively in response to KSHV reactivation signals. Modulation of DNA binding of RBP-Jk is a novel level
of regulation of the Notch pathway that has been underappreciated in the literature. The overall goal of this
application is to define the basic molecular mechanisms that regulate RBP-Jk DNA binding in KSHV infected
cells, and determine the transcriptional reprogramming that supports viral reactivation. Our studies will explain
the fundamental regulation of productive and non-productive virus reactivation as determined by promoter-
specific transactivation.
 We will therefore address these Specific Aims:
Aim 1. Determine if novel host proteins stimulate Jk binding to viral promoters during KSHV reactivation.
Aim 2. Determine how specific MBP/Jk/DNA complexes program Rta and Notch-dependent reactivation.
 A series of biochemical and molecular biological approaches are proposed. Protein-DNA interactions
represent the basis for many of the experiments, and will be evaluated in response to overexpression or
functional deletion of cellular proteins (termed ‘motif binding proteins’, or MBPs). Effects on viral reactivation will
be quantitated using a novel, highly quantitative, KSHV reporter virus. A major part of the project involves using
a novel version of Rta to detect and measure its direct targets by next generation sequencing. This proposal will
shed light on how Notch target genes are specified for transactivation, and reveal new components of the Notch
signal transduction pathway.

## Key facts

- **NIH application ID:** 10198741
- **Project number:** 5R21AI150230-02
- **Recipient organization:** RBHS-NEW JERSEY MEDICAL SCHOOL
- **Principal Investigator:** Vivian Bellofatto
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $196,250
- **Award type:** 5
- **Project period:** 2020-07-01 → 2024-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10198741

## Citation

> US National Institutes of Health, RePORTER application 10198741, Novel Notch regulation in KSHV reactivation (5R21AI150230-02). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10198741. Licensed CC0.

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