PDCD2 knockdown inhibits erythroid but not megakaryocytic lineage differentiation of human hematopoietic stem/progenitor cells

• Published in: Experimental hematology Vol. 40; no. 12; pp. 1028 - 1042.e3
• Main Authors: Kokorina, Natalia A, Granier, Celine J, Zakharkin, Stanislav O, Davis, Stephani, Rabson, Arnold B, Sabaawy, Hatem E
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Inc 01-12-2012
• Subjects: Advanced Basic Science; Antigens, CD34 - metabolism; Apoptosis Regulatory Proteins - genetics; Bone Marrow Cells - metabolism; Cell Differentiation - drug effects; Cell Differentiation - genetics; Cell Line, Tumor; Cell Proliferation; Cytarabine - pharmacology; Erythroid Cells - cytology; Erythroid Cells - drug effects; Erythroid Cells - metabolism; Gene Expression; Gene Expression Profiling; Gene Expression Regulation, Leukemic - drug effects; Gene Knockdown Techniques; Genetic Vectors - genetics; Hematology, Oncology and Palliative Medicine; Hematopoiesis - drug effects; Hematopoiesis - genetics; Hematopoietic Stem Cells - cytology; Hematopoietic Stem Cells - drug effects; Hematopoietic Stem Cells - metabolism; Humans; K562 Cells; Lentivirus - genetics; Leukemia - genetics; Megakaryocytes - cytology; Megakaryocytes - drug effects; Megakaryocytes - metabolism; RNA Interference; Transduction, Genetic
• ISSN: 0301-472X; 1873-2399
• DOI: 10.1016/j.exphem.2012.08.004

Programmed cell death-2 (PDCD2) protein is enriched in embryonic, hematopoietic, and neural stem cells, however, its function in stem/progenitor cell differentiation is unclear. We investigated the effects of PDCD2 knockdown on the development and differentiation of hematopoietic progenitor cells (HPC). CD34+ cells derived from normal human bone marrow and K562 leukemic cells were effectively transduced with short-hairpin RNA to knockdown PDCD2. Colony-forming assays were used to investigate the effects of PDCD2 loss on HPC clonogenic potential and on 12-O-tetradecanoyl-phorbol-13-acetate–and arabinofuranosylcytosine–induced terminal differentiation. In CD34+ clonogenic progenitors, PDCD2 knockdown decreased the total number of colony-forming units, increased the number of colony-forming units–granulocyte-erythroid-macrophage-megakaryocyte and burst-forming unit–erythroid primitive colonies, and decreased the number of burst-forming unit–erythroid mature colonies. Similar results were observed in K562 cells, suggesting that PDCD2 is important for HPC differentiation and/or survival, and for erythroid lineage commitment. Furthermore, 12-O-tetradecanoyl-phorbol-13-acetate–induced megakaryocytic differentiation and proliferation of K562 cells was not affected by PDCD2 knockdown. In contrast, arabinofuranosylcytosine-induced erythroid differentiation of K562 cells was significantly reduced with PDCD2 knockdown, with no effect on cell proliferation. The effects of PDCD2 knockdown were attributed to a cell cycle arrest at G0 /G1 , along with increased messenger RNA expression of early progenitor factors c-MYB and GATA-2 , and decreased expression of erythroid factors GATA-1 , EpoR, and γ -globin . We conclude that PDCD2 loss of function(s) impedes erythroid differentiation by inducing cell cycle arrest and increasing expression of early hematopoietic progenitor factors. These findings suggest that PDCD2 has a novel regulatory role in human hematopoiesis and is essential for erythroid development.