High GATA-2 expression inhibits human hematopoietic stem and progenitor cell function by effects on cell cycle

Area of Science:

• Hematology
• Molecular Biology
• Stem Cell Biology

Background:

• Transcription factor GATA-2 is a known regulator of murine hematopoietic stem cells.
• The precise role of GATA-2 in regulating cell proliferation and quiescence in human hematopoietic cells remains to be fully elucidated.

Purpose of the Study:

• To investigate the relationship between GATA-2 and cell proliferation in murine and human hematopoietic cells.
• To determine if GATA-2 influences quiescence and hematopoiesis in vitro and in vivo.

Main Methods:

• Induction of GATA-2 expression in murine and human hematopoietic cells.
• Analysis of cell quiescence markers (e.g., Pyronin Y staining).
• Assessment of hematopoietic stem and progenitor cell function using colony-forming cell (CFC) and long-term culture-initiating cell (LTC-IC) assays.
• In vivo hematopoiesis assays in NOD-SCID mice.
• Gene expression analysis of cell cycle regulators.

Main Results:

• Inducing GATA-2 increased quiescence (G0 residency) in both murine and human hematopoietic cells.
• Quiescent human cord blood cells (CD34(+)CD38(-)Hoechst(lo)Pyronin Y(lo)) exhibited higher GATA-2 expression than cycling cells.
• Enforced GATA-2 expression reduced proliferation and impaired CFC and LTC-IC assay performance.
• GATA-2 was found upstream of MEF, but MEF induction did not fully replicate GATA-2-conferred quiescence.
• GATA-2 induction reduced expression of cell cycle regulators CCND3, CDK4, and CDK6.
• In vivo, enforced GATA-2 expression inhibited human hematopoiesis in NOD-SCID mice, with reduced Ki-67 expression in contributing cells.

Conclusions:

• GATA-2 activity inhibits the cell cycle in hematopoietic stem and progenitor cells.
• GATA-2 acts as a molecular entry point into the transcriptional program regulating quiescence in human hematopoietic stem and progenitor cells.
• GATA-2 plays a critical role in maintaining hematopoietic stem cell quiescence, impacting both in vitro and in vivo hematopoiesis.