Functional Analysis Of The Inhibition Of Topoisomerase II Alpha By Linker Histone H1

Abstract

In higher eukaryotes, DNA is progressively packaged into chromatin. In these varying levels of compaction, linker histone H1 is a key player for mediating chromatin folding. As a result, linker histone H1 is involved in regulating cellular activities, such as gene transcription. Also essential for multiple cellular processes, topoisomerase II alpha (Top2a) is an enzyme that regulates DNA topology and thus is a target in cancer therapeutics. Previous studies in our lab have identified Top2a as an H1.3 binding partner by immunoprecipitation in embryonic stem cells. Further studies have shown that mouse histone H1.3 inhibits Top2a enzymatic activity in vitro. In this thesis, I pursued a functional analysis to confirm and analyze the inhibitory effect of human H1.3 on Top2a in vivo. We found that overexpression of hH1.3 significantly suppressed the growth of HeLa cancer cells and resulted in an increased cell population with abnormal mitotic chromosomes. These analyses may lead to a better understanding of the role of H1 and Top2a in chromatin structure and function.