The Role of HJURP in Centromere Specification and Inheritance Throughout the Cell Cycle

The faithful chromosome segregation during mitosis and meiosis is critical for ensuring that each daughter cell inherits the correct number of chromosomes to maintain genomic stability. The events of chromosome missegregation can lead to aneuploidy which is a hallmark of many diseases such as birth defects and cancer. Centromeres are chromosomal domains that direct the process of chromosome segregation by recruiting kinetochore apparatus during mitosis. Centromere identity in most eukaryotes is specified epigenetically by the incorporation of a centromere specific nucleosomes in which canonical histone H3 variant is replaced by the Centromere Protein A (CENP-A). Therefore, the assembly and propagation of centromeric nucleosomes are critical for maintaining centromere identity. Assembly of centromere specific nucleosomes in humans requires the dedicated CENP-A chaperone HJURP, and the Mis18 complex to couple the deposition of new CENP-A to the site of the pre-existing centromere. New CENP-A deposition occurs specifically in early G1 and during DNA replication existing CENP-A containing nucleosomes are stably inherited and partitioned to daughter strands. In this dissertation, I will describe how HJURP plays a dual role in centromere specification and is implicated in both: new CENP-A deposition as well as inheritance of existing CENP-A nucleosomes. Chapter one will contains a general introduction to how centromere identity is dictated and inherited across different species. Chapter two is dedicated to the requirement of HJURP self-association for new CENP-A deposition. In chapter three, I will describe optimization of proximity based labelling assays that we employed for identification of a mechanism governing CENP-A inheritance. The chapter four is dedicated to the role of HJURP and MCM2 chaperones in CENP-A retention across S phase. In chapter five I will describe new preliminary data exploring a potential role of WDR18 protein in HJURP protein stability.