Transcriptional activation of the Cdk inhibitor p21 by vitamin D-3 leads to the induced differentiation of the myelomonocytic cell line U937
Transcriptional activation of the Cdk inhibitor p21 by vitamin D-3 leads to the induced differentiation of the myelomonocytic cell line U937
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DOI：
10.1101/gad.10.2.142
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发表时间：
1996-01-15
影响因子：
10.5
通讯作者：
Freedman, LP
中科院分区：
文献类型：
--
作者：
Liu, M;Lee, MH;Freedman, LP
维生素 D 的激素形式，即 1,25-二羟基维生素 D-3，通过其同源核受体（维生素 D-3 受体，VDR）发挥作用，将诱导骨髓白血病细胞系最终分化为单核细胞/巨噬细胞。由于 VDR 通过以配体依赖性方式转录调节响应基因发挥作用，因此我们寻找受体的靶基因，该靶基因启动响应配体的分化过程。我们用 1,25-二羟基维生素 D-3 处理或未处理的细胞生成的探针筛选了从骨髓单核细胞 U937 细胞系制备的 cDNA 文库。我们在此报道差异杂交的候选克隆是 Cdk 抑制剂 p21(WAF1, CIP1)。此外，我们发现 p21 是由 1,25-二羟基维生素 D-3 以 VDR 依赖性而非 p53 依赖性方式转录诱导的，并且我们在 p21 启动子中鉴定了功能性维生素 D 反应元件。在缺乏 1,25-二羟基维生素 D-3 的情况下，U937 细胞中 p21 和/或相关 Cdk 抑制剂 p27 的瞬时过表达导致单核细胞/巨噬细胞特异性标记物的细胞表面表达，表明配体调节的 p21 基因转录诱导促进了该单核细胞系的诱导分化。我们相信，这是第一份证明 Cdk 抑制剂（例如 p21 或 p27）的异位过度表达直接导致终末分化程序的报告。
The hormonal form of vitamin D, 1,25-dihydroxyvitamin D-3, acting through its cognate nuclear receptor (vitamin D-3 receptor, VDR) will induce myeloid leukemic cell lines to terminally differentiate into monocytes/macrophages. Because VDR acts by transcriptionally regulating responsive genes in a ligand-dependent manner, we sought target genes of the receptor that initiate the differentiation process in response to ligand. We screened a cDNA library prepared from the myelomonocytic U937 cell line with probes generated from either 1,25-dihydroxyvitamin D-3-treated or untreated cells. We report here that a candidate clone that hybridized differentially is the Cdk inhibitor p21(WAF1, CIP1). Furthermore, we show that p21 is transcriptionally induced by 1,25-dihydroxvitamin D-3 in a VDR-dependent, but not p53-dependent, manner, and we identify a functional vitamin D response element in the p21 promoter. Transient overexpression of p21 and/or the related Cdk inhibitor p27 in U937 cells in the absence of 1,25-dihydroxvitamin D-3 results in the cell-surface expression of monocyte/macrophage-specific markers, suggesting that ligand-modulated transcriptional induction of the p21 gene facilitates the induced differentiation of this monoblastic cell line. We believe that this is the first report demonstrating that the ectopic overexpression of a Cdk inhibitor such as p21 or p27 directly leads to a terminal differentiation program.