The Cancer Institute of New Jersey, New Brunswick, NJ 08901, USA.
Exp Hematol. 2012 Dec;40(12):1028-1042.e3. doi: 10.1016/j.exphem.2012.08.004. Epub 2012 Aug 22.
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.
程序性细胞死亡因子 2（PDCD2）蛋白在胚胎、造血和神经干细胞中含量丰富，但其在干细胞/祖细胞分化中的功能尚不清楚。我们研究了 PDCD2 敲低对造血祖细胞（HPC）发育和分化的影响。正常人类骨髓 CD34(+)细胞和 K562 白血病细胞均能有效地被短发夹 RNA 转导以敲低 PDCD2。集落形成实验用于研究 PDCD2 缺失对 HPC 克隆形成潜能和 12-O-十四烷酰佛波醇-13-乙酸盐和阿糖胞苷诱导的终末分化的影响。在 CD34(+)集落形成祖细胞中，PDCD2 敲低减少了集落形成单位总数，增加了集落形成单位-粒细胞-红细胞-巨噬细胞-巨核细胞和红细胞原始集落形成单位的数量，减少了红细胞成熟集落形成单位的数量。在 K562 细胞中也观察到了类似的结果，表明 PDCD2 对 HPC 分化和/或存活以及红细胞谱系的决定是重要的。此外，12-O-十四烷酰佛波醇-13-乙酸盐诱导的 K562 细胞巨核细胞分化和增殖不受 PDCD2 敲低的影响。相比之下，PDCD2 敲低显著降低了阿糖胞苷诱导的 K562 细胞的红细胞分化，而对细胞增殖没有影响。PDCD2 敲低的作用归因于 G(0)/G(1)期细胞周期停滞，同时早期祖细胞因子 c-MYB 和 GATA-2 的信使 RNA 表达增加，红细胞因子 GATA-1、EpoR 和 γ-珠蛋白的表达减少。我们得出结论，PDCD2 功能丧失通过诱导细胞周期停滞和增加早期造血祖细胞因子的表达来阻碍红细胞分化。这些发现表明 PDCD2 在人类造血中具有新的调节作用，并且对红细胞发育至关重要。
