Submitted June 5, 2008
Accepted December 16, 2008
High GATA-2 expression inhibits human hematopoietic stem and progenitor cell function via effects on cell cycle
Alex J. Tipping, Cristina Pina, Anders Castor, Dengli Hong, Neil P. Rodrigues, Lorenza Lazzari, Gillian E. May, Sten Eirik W. Jacobsen, and Tariq Enver*
MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom
Hematopoietic Stem Cell Laboratory, Lund Strategic Research Center for Stem Cell Biology & Cell Therapy, Lund University, Lund, Sweden
Cell Factory, Center for Transfusion Medicine, Cellular Therapy and Cryobiology, Fondazione Ospedale Maggiore Policlinico, Mangiagalli e Regina Elena, Milan, Italy
Haematopoietic Stem Cell Laboratory, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, United Kingdom
* Corresponding author; email: tenver{at}gwmail.jr2.ox.ac.uk.
Evidence suggests the transcription factor GATA-2 functions as a critical regulator of murine HSCs. Here we have explored the relationship between GATA-2 and cell proliferation and show that inducing GATA-2 activity increases quiescence (G0 residency) of murine and human hematopoietic cells. In the clinically-relevant context of human cord blood, quiescent fractions (CD34+CD38-HoechstloPyronin Ylo) express more GATA-2 than cycling counterparts. Enforcing GATA-2 expression also increased quiescence of cord blood cells, reducing proliferation and performance in LTC-IC and CFC assays. Gene expression analysis places GATA-2 upstream of the quiescence regulator MEF, but enforcing MEF expression does not prevent GATA-2-conferred quiescence, suggesting additional regulators are involved. Although known quiescence regulators p21CIP1 and p27KIP1 do not appear to be responsible, enforcing GATA-2 reduced expression of regulators of cell cycle entry and progression like CCND3, CDK4 and CDK6. Enforcing GATA-2 inhibited human hematopoiesis in vivo: cells with highest exogenous expression (GATA-2hi) failed to contribute to hematopoiesis in NOD/SCID mice whilst GATA-2lo cells contributed with delayed kinetics and low efficiency, with reduced expression of Ki-67. Thus GATA-2 activity inhibits cell cycle in vitro and in vivo, highlighting GATA-2 as a molecular entry point into the transcriptional program regulating quiescence in human hematopoietic stem and progenitor cells.
