Title

A comprehensive analysis of Dot1L action in mouse embryonic stem cells: A unique histone methyltransferase required for cell cycle progression and gene expression

Date of Completion

January 2009

Keywords

Biology, Molecular|Biology, Genetics

Degree

Ph.D.

Abstract

The great potential for using embryonic stem cells (ESC) in therapies for a wide spectrum of diseases has caused tremendous interest in the basic biology of these unique cells. ESCs are vastly different than somatic cells in many ways. They rapidly proliferate while maintaining an undifferentiated state while retaining the ability to form any cell type in the body. The mechanisms that allow ESCs to maintain this state is an intense area of research. One way ESCs maintain their pluripotency is through epigenetics and specialized chromatin such as histone modifications and DNA methylation. One histone modifying enzyme, Dot1L (Disruptor of Telomeric Silencing Like), which methylates histone 3 lysine 79 (H3K79), has gained much attention in recent years, mainly because of its known role in leukemogenesis and potential as a therapeutic target. We aimed to determine the role of Dot1L in embryonic stem cell function. We find that Dot1L is critical for progression through the cell cycle and proliferation during differentiation. Loss of Dot1L leads to a delay in mitosis, chromosome instability and formation of tetraploid and aneuploid cells without inducing apoptosis In addition, loss of Dot1L and H3K79 methylation leads to the misregulation of a select set of genes. We provide here the most comprehensive analysis of Dot1L function in mammalian cells to date and provide a model for loss of Dot1L function in ESCs as well as leukemic cells. ^