The Spindle Assembly Checkpoint Is Required for Hematopoietic Progenitor Cell Engraftment

The spindle assembly checkpoint plays a pivotal role in preventing aneuploidy and transformation. Many studies demonstrate impairment of this checkpoint in cancer cells. While leukemia is frequently driven by transformed hematopoietic stem and progenitor cells (HSPCs), the biology of the spindle assembly checkpoint in such primary cells is not very well understood. Here, we reveal that the checkpoint is fully functional in murine progenitor cells and, to a lesser extent, in hematopoietic stem cells. We show that HSPCs arrest at prometaphase and induce p53-dependent apoptosis upon prolonged treatment with anti-mitotic drugs. Moreover, the checkpoint can be chemically and genetically abrogated, leading to premature exit from mitosis, subsequent enforced G1 arrest, and enhanced levels of chromosomal damage. We finally demonstrate that, upon checkpoint abrogation in HSPCs, hematopoiesis is impaired, manifested by loss of differentiation potential and engraftment ability, indicating a critical role of this checkpoint in HSPCs and hematopoiesis. In this report, Andreas Brown and colleagues demonstrate that cycling hematopoietic stem and progenitor cells activate the spindle assembly checkpoint as a response to anti-mitotic stress. The authors further reveal that inhibition of the checkpoint causes impairment of progenitor function, whereas it appears to be less crucial for hematopoietic stem cells.