Loss of <I>Nupr1</I> promotes engraftment by tuning the quiescence threshold of hematopoietic stem cells via regulation of the p53-checkpoint pathway

Abstract

Hematopoietic stem cells (HSCs) are dominantly quiescent under homeostasis, which is a key mechanism of maintaining the HSC pool for life-long hematopoiesis. Dormant HSCs poise to be immediately activated on urgent conditions and can return to quiescence after regaining homeostasis. To date, the molecular networks of regulating the threshold of HSC dormancy, if exist, remain largely unknown. Here, we unveiled that deletion of <i>Nupr1</i>, a gene preferentially expressed in HSCs, activated the quiescence HSCs under homeostatic status, which conferred engraftment competitive advantage on HSCs without compromising their stemness and multi-lineage differentiation abilities in serial transplantation settings. Following an expansion protocol, the Nupr1-/- HSCs proliferate more robustly than their wild type counterparts <i>in vitro</i>. Nupr1 inhibits the expression of p53 and the rescue of which offsets the engraftment advantage. Our data unveil the <i>de novo</i> role of <i>Nupr1</i> as an HSC quiescence-regulator, which provides insights into accelerating the engraftment efficacy of HSC transplantation by targeting the HSC quiescence-controlling network.