Molecular and Genetic Analysis of Novel Epigenetic Silencing Factors Dhp1, Lsd1, and Lsd2

Epigenetic mechanisms regulate when, where, and how an organism uses the genetic information stored in its genome. They are essential to many cellular processes, such as the regulation of gene expression, genome organization, and cell-fate determination. In following chapters, we use molecular and genetic analyses to investigate the role of novel factors in epigenetic silencing, using S. pombe as a model system. The second chapter focuses on the role of 5’ to 3’ exoribonuclease Dhp1 in epigenetic silencing using a partially functional dhp1 mutant, dhp1-1. We employ genetic assays to define the role of Dhp1 in the sequential stages of heterochromatin formation (establishment, spreading, and maintenance). We also use genetic interaction studies to show that Dhp1-mediated silencing operates as a post-transcriptional gene silencing (PTGS) mechanism independently of previously identified PTGS mechanisms. In the third chapter, we attempt to elaborate on the mechanism of Dhp1-mediated silencing via genetic analysis of Dhp1-interacting proteins but are unable to identify a simple functional connection between Dhp1 and the selected candidate factors: novel gene SPAC25G10.01, Rix1 complex member Ipi1, and histone deacetylases Lsd1 and Lsd2. We are however able to identify previously unreported genetic interactions between SPAC25G10.01Δ and mutants of histone deacetylases Clr3 and Sir2. We also generate novel lsd1 and lsd2 mutants for these analyses, which reveal a role for these enzymes in epigenetic silencing. In the fourth chapter, we use the novel lsd1 and lsd2 mutant strains to further investigate the role of Lsd1 and Lsd2 in essential functions beyond their known catalytic activity. Genetic analyses suggest that Lsd1 and Lsd2 serve divergent roles, regulate one another, and may have parallel roles in epigenetic silencing with other histone modifiers.

Grantor dc:publisher

Wake Forest University

Year dc:date.issued

2018

Author dc:creator

• Tucker, James Franklin

• Epigenetic Silencing

Language dc:language.iso

en

Handle dc:identifier.uri

http://hdl.handle.net/10339/93042

OAI identifier oai:identifier

oai:wakespace.lib.wfu.edu:10339/93042