# Nuclear DAB2IP regulates DNA replication initiation through activating PLK1-mediated HBO1 phosphorylation

## TL;DR

This paper reveals how the tumor suppressor DAB2IP helps start DNA replication by enabling a key protein interaction that maintains genome stability.

## Contribution

The study identifies a novel role of DAB2IP in promoting DNA replication origin firing through PLK1-mediated HBO1 phosphorylation.

## Key findings

- DAB2IP promotes DNA replication by enhancing HBO1–PLK1 interaction and HBO1 phosphorylation.
- Phosphorylated HBO1 acetylates histone H3K14, enabling MCM complex loading for DNA replication.
- Loss of DAB2IP phosphorylation causes genomic instability and replication defects.

## Abstract

DAB2IP (Disabled homolog 2 interacting protein), a recognized tumor suppressor, plays a pivotal role in regulating various oncogenic pathways. Our previous research demonstrated that DAB2IP functions as a cell cycle regulator by facilitating PLK1-mediated mitosis progression. Here, we elucidate a novel function of DAB2IP in promoting DNA replication origin firing. Mechanistically, we identified that DAB2IP localizes to the nucleus, where it interacts with the histone acetyltransferase HBO1 and enhances the HBO1–PLK1 interaction. DAB2IP facilitates PLK1-mediated phosphorylation of HBO1, which subsequently promotes HBO1-directed acetylation of histone 3 at lysine 14 (H3K14Ac). This modification enables the loading of the minichromosome maintenance protein (MCM) complex onto chromatin, thereby supporting DNA replication and maintaining genome integrity. Additionally, we found that ATR regulates CDK1-mediated phosphorylation of DAB2IP, and that this phosphorylation is essential for the formation and activation of the HBO1-PLK1 complex. Ablation of DAB2IP phosphorylation results in increased genomic instability due to incomplete replication of genomic DNA, as evidenced by the accumulation of anaphase ultrafine bridges and 53BP1 nuclear bodies in G1 phase of the cell cycle. In summary, our findings underscore the critical regulatory role of DAB2IP in DNA replication initiation and genomic stability maintenance, providing new insights into its function in cellular homeostasis.

Graphical Abstract