Hypoxia Inducible Factor-1α Directly Induces the Expression of Receptor Activator of Nuclear Factor-κB Ligand in Periodontal Ligament Fibroblasts
Hypoxia Inducible Factor-1α Directly Induces the Expression of Receptor Activator of Nuclear Factor-κB Ligand in Periodontal Ligament Fibroblasts
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DOI：
10.1007/s10059-011-1055-x
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发表时间：
2011-06-01
影响因子：
3.8
通讯作者：
Baek, Jeong-Hwa
中科院分区：
文献类型：
--
作者：
Park, Hyun-Jung;Baek, Kyung Hwa;Baek, Jeong-Hwa
正畸牙齿移动过程中，牙周组织受压侧局部缺氧，破骨细胞生成增强。核因子-kappa B配体受体激活剂（RANKL）是一种成骨细胞/基质细胞衍生因子，对于破骨细胞生成至关重要。在这项研究中，我们研究了缺氧对人牙周膜成纤维细胞（PDLFs）中RANKL表达的影响，以探讨局部缺氧与牙周组织受压侧破骨细胞生成增强之间的关系。缺氧显著增加PDLFs中RANKL mRNA和蛋白以及缺氧诱导因子-1 α（HIF-1 α）蛋白的水平。在常氧条件下，组成型活性HIF-1 α单独显著增加PDLFs中RANKL表达水平，而显性负性HIF-1 α阻断缺氧诱导的RANKL表达。为了进一步研究HIF-1 α是否直接调节RANKL转录，使用含有RANKL启动子序列的报告载体进行荧光素酶报告基因测定。暴露于缺氧或组成型活性HIF-1 α的过表达显著增加了RANKL启动子活性，而显性负性HIF-1 α阻断了缺氧诱导的RANKL启动子活性。此外，RANKL启动子中假定的HIF-1 α结合元件的突变阻止了缺氧诱导的RANKL启动子活性。染色质免疫沉淀结果显示，缺氧或组成性激活的HIF-1 α增加了HIF-1 α与RANKL启动子的DNA结合。这些结果表明，HIF-1 α介导缺氧诱导的RANKL表达上调，并且在压迫侧牙周膜中，缺氧至少部分地通过增加PDLFs中RANKL表达来增强破骨细胞生成。
During orthodontic tooth movement, local hypoxia and enhanced osteoclastogenesis are observed in the compression side of periodontal tissues. The receptor activator of nuclear factor-kappa B ligand (RANKL) is an osteoblast/stromal cell-derived factor that is essential for osteoclastogenesis. In this study, we examined the effect of hypoxia on RANKL expression in human periodontal ligament fibroblasts (PDLFs) to investigate the relationship between local hypoxia and enhanced osteoclastogenesis in the compression side of periodontal tissues. Hypoxia significantly enhanced the levels of RANKL mRNA and protein as well as hypoxia inducible factor-1 alpha (HIF-1 alpha) protein in PDLFs. Constitutively active HIF-1 alpha alone significantly increased the levels of RANKL expression in PDLFs under normoxic conditions, whereas dominant negative HIF-1 alpha blocked hypoxia-induced RANKL expression. To investigate further whether HIF-1 alpha directly regulates RANKL transcription, a luciferase reporter assay was performed using the reporter vector containing the RANKL promoter sequence. Exposure to hypoxia or overexpression of constitutively active HIF-1 alpha significantly increased RANKL promoter activity, whereas dominant negative HIF-1 alpha blocked hypoxia-induced RANKL promoter activity. Furthermore, mutations of putative HIF-1 alpha binding elements in RANKL promoter prevented hypoxia-induced RANKL promoter activity. The results of chromatin immunoprecipitation showed that hypoxia or constitutively active HIF-1 alpha increased the DNA binding of HIF-1 alpha to RANKL promoter. These results suggest that HIF-1 alpha mediates hypoxia-induced up-regulation of RANKL expression and that in compression side periodontal ligament, hypoxia enhances osteoclastogenesis, at least in part, via an increased RANKL expression in PDLFs.