Regulation of canonical and non-canonical substrates of histone lysine methyltransferases

This Project Grant award of $442,750, funded by the National Institute of General Medical Sciences (NIGMS) under the Biomedical Research and Research Training program (CFDA 93.859), supports fundamental research into the regulation of histone lysine methyltransferase (HLMT) substrates. Awarded to Virginia Polytechnic Institute & State University on August 1, 2025, with a completion date of June 30, 2030, the research addresses critical gaps in understanding how cells maintain epigenetic identity during cell division and development. The project focuses on two primary research objectives: investigating the mechanisms of active chromatin inheritance and temporo-spatial regulation of HLMTs during mitosis, and developing novel methodologies to systematically identify and characterize non-histone substrates of HLMTs and their roles in early developmental processes.

The research outputs will advance understanding of protein lysine methylation as a post-translational modification critical to cell differentiation, chromatin organization, and disease prevention. By establishing new research platforms and approaches to investigate both canonical and non-canonical methylation events, this project aims to provide mechanistic insights that could inform therapeutic strategies for preventing developmental disorders and cancer associated with dysregulated histone lysine methylation. The five-year award period enables comprehensive investigation of epigenetic inheritance mechanisms, a nascent research discipline with significant implications for understanding cellular identity maintenance and developmental biology.

Abstract

Protein lysine methylation is a post-translational modification (PTM) that neutralizes the positive charged side chain and modulates protein functions in many key biological events. In metazoans, somatic cells displaying distinct cellular phenotypes are originated from one zygote and contain the identical sequence of DNA. Upon differentiation, transition of cell fate is initiated by lineage transcription factors and a cell identity is stabilized by epigenetic factors that define a chromatin state. Distinct histone lysine methylation is central to active or repressive chromatin formation. Dysregulation of this process often leads to pathogenic conditions such as developmental disorders or cancer. Once an epigenetic state is established, cells need to faithfully recapitulate the steady state in mitosis in order to safeguard cell identity and prevent developmental dysregulation and oncogenic transformation. The epigenetic inheritance is a new research discipline undergoing rigorous investigations. Despite that significant advancement has been achieved to decipher the mechanisms of repressive chromatin inheritance, how active chromatin is inherited, involving temporo-spatial regulations of histone lysine methyltransferases, still remains elusive. In addition to histones, histone lysine methyltransferases also catalyze non-histone methylation events, whose importance is emerging in the context of early development. However, there is a lack of systematic investigation of these non-canonical substrates and how they critically regulate distinct biological processes. In this proposal, we will address these key knowledge gaps by interrogating the mechanistic questions in active chromatin inheritance and develop a new approach to investigate non-canonical methylation events by histone lysine methyltransferases. We expect to establish new research platforms and advance our understanding towards methylation biology.