o:3470 Kinase-inactivated CDK6 preserves the long-term functionality of adult hematopoietic stem cells en 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. Cyclin-Dependent Kinase 6 Metabolism Genetics; Animals; Hematopoietic Stem Cells Metabolism Cytology; Mice; Humans; Adult Stem Cells Metabolism Cytology; Cell Proliferation; Cell Differentiation; Mice, Inbred C57BL; Hematopoietic Stem Cell Transplantation; Cell Self Renewal Drug effects 1552099 10.1182/blood.2023021985 2024-09-03T07:54:17.981Z 44 yes 46 Isabella M. Mayer University of Veterinary Medicine Vienna 0000-0002-9164-9547 Eszter Doma University of Veterinary Medicine Vienna person 0000-0003-2989-1022 Thorsten Klampfl University of Veterinary Medicine Vienna person 0000-0002-6666-9773 Michaela Prchal-Murphy University of Veterinary Medicine Vienna person Sebastian Kollmann University of Veterinary Medicine Vienna person 0000-0001-7911-9896 Alessia Schirripa University of Veterinary Medicine Vienna person 0000-0001-5446-9136 Lisa Scheiblecker University of Veterinary Medicine Vienna person Markus Zojer University of Veterinary Medicine Vienna person Natalia Kunowska University of Graz person Lea Gebrail University of Veterinary Medicine Vienna person Lisa E. Shaw Medical University of Vienna person 0000-0003-2273-7655 Ulrike Mann Medical University of Vienna person Alex Farr Medical University of Vienna person 0000-0002-4628-9052 Reinhard Grausenburger University of Veterinary Medicine Vienna person 0000-0002-5972-3372 Gerwin Heller Medical University of Vienna person Eva Zebedin-Brandl Medical University of Vienna person Matthias Farlik Medical University of Vienna person 0000-0003-0698-2992 Marcos Malumbres Vall d'Hebron Institute of Oncology / Spanish National Cancer Research Centre / Institució Catalana de Recerca i Estudis Avançats person Veronika Sexl University of Veterinary Medicine Vienna / Universität Innsbruck person 0000-0001-9363-0412 Karoline Kollmann University of Veterinary Medicine Vienna person 0000-0002-7937-4245 application/pdf 5803023 https://phaidra.vetmeduni.ac.at/o:3470 no yes 18 70 1552253 Blood 15 144 2 156 170 American Society of Hematology 2024