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Role of a novel Zn finger transcriptional regulator involved in osteoclastogenesis

新型锌指转录调节因子在破骨细胞生成中的作用

基本信息

批准号：
11671846
负责人：
KUKITA Akiko
金额：
$ 2.3万
依托单位：
Saga Medical School
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11671846/
关键词：
osteoclast differentiation transcription factor

项目摘要

Osteoclasts and macrophage are closely related cells and are thought to be derived from common progenitor cells. A zinc finger transcription factor, Egr-1 was found to be a positive modulator of macrophage differentiation. We previously have shown that blocking Egr-1 expression by antisense oligonucleotides results in the stimulation of osteoclast differentiation in bone marrow culture. These data suggested that factor which inhibits Egr-1 function is involved in osteoclast differentiation. In this study, we show a BTB/POZ Zn finger gene, OCZF (osteoclast-derived zinc finger protein) isolated from osteoclast cDNA library efficiently suppresses Egr-1-dependent transcriptional activity. Analysis of the activity of deletion mutant OCZF proteins showed that the POZ and proline-rich domains contribute the activity of transcription repression. The trichostatin A (TSA), a specific inhibitor of histone deacetylases (HDAC) significantly reduced the repression effect of OCZF.Interestingly, the addition of TSA severely reduced osteoclast differentiation in bone marrow culture. TSA also strongly inhibited osteoclast differentiation from a macrophage cell line, RAW 264 which can differentiate into osteoclasts by the stimulation of RANKL.We also found that the expression of OCZF was increased along the osteoclast differentiation in this cell line, RAW 264. Ecotropic expression of OCZF in RAW 264 cells resulted in growth inhibition. These results suggest that OCZF is a unique transcriptional regulator which selectively represses the transcription of Egr-1-responsive gene and is induced by RANKL and participates in the regulation of cell growth in macrophage cell. In addition, we show that HDAC activity is required for osteoclast differentiation and OCZF may be contributed to the partial activity of HDAC necessary for osteoclast differentiation.

破骨细胞和巨噬细胞是密切相关的细胞，被认为是来自共同的祖细胞。锌指转录因子Egr-1被发现是巨噬细胞分化的积极调节剂。我们之前已经证明，通过反义寡核苷酸阻断Egr-1表达可刺激骨髓培养中的破骨细胞分化。这些数据提示抑制Egr-1功能的因子参与了破骨细胞的分化。在这项研究中，我们展示了从破骨细胞cDNA文库中分离的BTB/POZ锌指基因OCZF（破骨细胞衍生锌指蛋白）有效抑制egr -1依赖性转录活性。对缺失突变体OCZF蛋白的活性分析表明，POZ和富含脯氨酸的结构域参与了转录抑制活性。组蛋白去乙酰化酶（HDAC）特异性抑制剂曲古霉素A （TSA）显著降低了OCZF的抑制作用。有趣的是，TSA的加入严重降低了骨髓培养中破骨细胞的分化。TSA还能强烈抑制巨噬细胞RAW 264的破骨细胞分化，RAW 264可通过刺激RANKL向破骨细胞分化。我们还发现OCZF的表达在该细胞系RAW 264中随着破骨细胞的分化而增加。OCZF在RAW 264细胞中的亲生态表达可抑制细胞生长。这些结果表明，OCZF是一种独特的转录调节剂，可选择性抑制egr -1应答基因的转录，受RANKL诱导，参与巨噬细胞的细胞生长调控。此外，我们发现HDAC活性是破骨细胞分化所必需的，OCZF可能有助于破骨细胞分化所需的HDAC的部分活性。