The role of degradation pathways on cell stemness and fate determination
The haematopoietic system relies on the potential of haematopoietic stem cells (HSCs) to self-renew and differentiate into all lineages of mature blood cells, and is a reference model to study differentiation hierarchies. Cell fate determination results from different layers of regulation, including transcriptional, translational, epigenetic, metabolic, and cell biological changes. Degradation pathways, such as autophagy and the proteasome, play mechanistically relevant roles that in principle may impact on all these layers. Indeed, catabolic degradation results in the building blocks necessary for anabolic processes, while it also preserves stemness and regenerative potential. Asymmetric cell division (ACD) has been extensively reported to contribute to maintenance of stemness by the rise of daughters with divergent fates in stem cells, including HSCs. Taken together, I postulate that degradation pathways work synergistically to give rise to the asymmetric fates observed in HSCs differentiation and can be targeted for future therapeutic use in humans. I plan to test this by 1. establishing an efficient strategy to image asymmetric inheritance of cargo by long-term ex vivo HSCs expansion, 2. verifying whether autophagosomes and proteasomes are co-inherited in HSCs mitoses, and 3. assessing the impact of cargo segregation by ACD on HSC maintenance and differentiation. I will use state-of-the-art techniques and novel murine models to assess the molecular and cell biological mechanisms of ACD modulation on HSC maintenance, relying on imaging of known and potentially novel components that are asymmetrically inherited by HSCs and able to impact their fate determination. Finally, I will further evaluate the in vivo impact of cargo inheritance on haematopoiesis by using single-cell transplantation. The knowledge derived from this project will potentially boost the development of novel regenerative medicine therapeutic approaches.