title: PDCD2 knockdown inhibits erythroid but not megakaryocytic lineage differentiation of human hematopoietic stem/progenitor cells.
abstract: 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 G(0)/G(1), 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.
authors.affiliation: The Cancer Institute of New Jersey, New Brunswick, NJ 08901, USA.
authors.forename: Natalia A
authors.initials: NA
authors.lastname: Kokorina
authors.forename: Celine J
authors.initials: CJ
authors.lastname: Granier
authors.forename: Stanislav O
authors.initials: SO
authors.lastname: Zakharkin
authors.forename: Stephani
authors.initials: S
authors.lastname: Davis
authors.forename: Arnold B
authors.initials: AB
authors.lastname: Rabson
authors.forename: Hatem E
authors.initials: HE
authors.lastname: Sabaawy
mesh_terms: D018952:Antigens, CD34 / Q000378:metabolism; D051017:Apoptosis Regulatory Proteins / Q000235:genetics*; D001854:Bone Marrow Cells / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects / Q000235:genetics*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D003561:Cytarabine / Q000494:pharmacology; D041905:Erythroid Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D015870:Gene Expression; D020869:Gene Expression Profiling; D015973:Gene Expression Regulation, Leukemic / Q000187:drug effects; D055785:Gene Knockdown Techniques; D005822:Genetic Vectors / Q000235:genetics; D006410:Hematopoiesis / Q000187:drug effects / Q000235:genetics; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D020014:K562 Cells; D016086:Lentivirus / Q000235:genetics; D007938:Leukemia / Q000235:genetics; D008533:Megakaryocytes / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D034622:RNA Interference; D014161:Transduction, Genetic
chemical_list: D018952:Antigens, CD34; D051017:Apoptosis Regulatory Proteins; C094601:PDCD2 protein, human; D003561:Cytarabine