The role of HDAC9 in JAK2V617F-driven myeloproliferative neoplasms

Janus kinase 2 (JAK2) encodes a protein tyrosine kinase that is critical for haematopoiesis. JAK2 functions by modulating signal transduction between the receptor and the JAK-STAT, ERK1/2 and AKT phosphorylation signalling pathways. The mutation, JAK2V617F, loses the ability to inhibit autophosphorylation, the result of which is a chronically active kinase which causes aberrant signalling. The influence of JAK2V617F has yet to be fully elucidated in haematopoietic stem cells (HSCs). In this work I present a new model for JAK2V617F in HSCs and have identified a gene, HDAC9, that has potential as a possible target for treatment. In Chapter 3, I describe the experiments that explain the construction of my model and how I probed it with the aim to characterise it with a focus on signalling and DNA damage/DNA damage repair. An investigation into DNA damage/repair suggests that JAK2V617F exerts both increased DNA damage and an increased ability to repair such damage. In Chapter 4, I provide a cross-publication dataset analysis to compare the RNA-sequencing analysis of my data to current models and patient data to gauge the relevance of my data. I utilise my RNA-sequencing data alongside bioinformatic programs to explain how the data relays back to Chapter 3. I have provided a comprehensive validation programme to validate my RNA-sequencing data through RT-PCR. Finally in Chapter 5, I investigate the role of HDAC9 in cell signalling, cell proliferation, and DNA damage response. The data presented within this chapter suggests that HDAC9 is essential for JAK-STAT signalling in HSCs and through STAT regulation, has a role in cell proliferation and DNA damage. Altogether, these findings reveal new insight into the role of HDAC9 in JAK2V617F expressing HSCs.