Kinase-inactivated CDK6 preserves the long-term functionality of adult hematopoietic stem cells
Isabella Maria Mayer, Eszter Doma, Thorsten Klampfl, Michaela Prchal‐Murphy, Sebastian Kollmann, Alessia Schirripa, Lisa Scheiblecker, Markus Zojer, Natalia Kunowska, Lea Gebrail, Lisa E. Shaw, Ulrike Mann, Alex Farr, Reinhard Grausenburger, Gerwin Heller, Eva Zebedin-Brandl, Matthias Farlik, Marcos Malumbres, Veronika Sexl, Karoline Kollmann
Abstract
ABSTRACT: Hematopoietic stem cells (HSCs) are characterized by the ability to self-renew and to replenish the hematopoietic system. The cell-cycle kinase cyclin-dependent kinase 6 (CDK6) regulates transcription, whereby it has both kinase-dependent and kinase-independent functions. Herein, we describe the complex role of CDK6, balancing quiescence, proliferation, self-renewal, and differentiation in activated HSCs. Mouse HSCs expressing kinase-inactivated CDK6 show enhanced long-term repopulation and homing, whereas HSCs lacking CDK6 have impaired functionality. The transcriptomes of basal and serially transplanted HSCs expressing kinase-inactivated CDK6 exhibit an expression pattern dominated by HSC quiescence and self-renewal, supporting a concept, in which myc-associated zinc finger protein (MAZ) and nuclear transcription factor Y subunit alpha (NFY-A) are critical CDK6 interactors. Pharmacologic kinase inhibition with a clinically used CDK4/6 inhibitor in murine and human HSCs validated our findings and resulted in increased repopulation capability and enhanced stemness. Our findings highlight a kinase-independent role of CDK6 in long-term HSC functionality. CDK6 kinase inhibition represents a possible strategy to improve HSC fitness.