Exploring the role of the Notch signalling pathway in normal and malignant human haematopoiesis

Lampreia, Fabio 2019. Exploring the role of the Notch signalling pathway in normal and malignant human haematopoiesis. PhD Thesis, Cardiff University. Item availability restricted.

Preview	PDF - Accepted Post-Print Version Download (4MB) | Preview
	PDF (Cardiff University Electronic Publication Form) - Supplemental Material Restricted to Repository staff only Download (352kB)

Abstract

Haematopoietic stem cells (HSCs) possess self-renewal capacity and give rise to the entire blood and immune systems. Notch is an evolutionarily conserved signalling pathway activated by cell-to-cell interactions with roles in stem cell maintenance, survival and differentiation. While studies in the murine haematopoietic system have proposed different roles for Notch signalling under stress and steady-state conditions, whether Notch is involved in the regulation of human haematopoietic stem/progenitor cells (HSPCs) has been scarcely explored. Here, we showed HSPCs express mainly Notch1 and Notch2 receptors and possess an active Notch pathway. We employed pharmacological inhibition by using the γ-secretase inhibitor DAPT and shRNA-mediated silencing of Notch pathway members (NCSTN and RBPJ) in human HSPCs. Notch inhibition led to reduced colony forming capacity in vitro and reduced frequency of immunophenotypic HSCs. Additionally, Notch inhibition caused decreased myelo-lymphoid engraftment in vivo along with deregulation of most stem/progenitor cell compartments, of which the HSC fraction was the most affected. Silencing RBPJ additionally impaired B cell development both in vitro and in vivo. These data contrast with the studies on the mouse haematopoietic system and suggest an essential role for Notch in the regulation of human HSCs. Malignant transformation of HSPCs lead to the development of haematological malignancies such as leukaemias. Here, we characterised Notch signalling in Acute Myeloid Leukaemia (AML) and showed that this pathway appears to be mostly silenced in this context. Reactivation of the pathway via membrane-bound Notch ligand and via a soluble Jag1 based peptide decreased proliferation and induced apoptosis in various AML cell lines. Furthermore, small molecule agonists of Notch were tested for their potential therapeutic value. All in all, our data further support the notion that Notch reactivation may exhibit therapeutic significance in some instances of AML.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Biosciences
Subjects:	Q Science > Q Science (General) R Medicine > R Medicine (General)
Date of First Compliant Deposit:	12 March 2020
Last Modified:	31 May 2021 01:21
URI:	https://orca.cardiff.ac.uk/id/eprint/130366

Actions (repository staff only)

Edit Item