Department of Food Science and Human Nutrition, Michigan State University, East Lansing, MI 48824, USA.
J Nutr. 2010 Aug;140(8):1502-8. doi: 10.3945/jn.110.122556. Epub 2010 Jun 9.
Myeloid dendritic cells (DC) are specialized antigen-presenting immune cells. Upon activation in peripheral tissues, DC migrate to lymph nodes to activate T lymphocytes. Matrix metalloproteinase (MMP)-9 is a gelatinase essential for DC migration. We have previously shown that all-trans retinoic acid (atRA), a bioactive metabolite of vitamin A, significantly augmented DC MMP-9 mRNA and protein production. We investigated the mechanisms by which atRA increased MMP-9 activity in vitro. Mouse myeloid DC cultured with atRA demonstrated increased gelatinase activity compared with cells cultured with retinoic acid receptor (RAR)-alpha antagonist. Adding MMP-9 inhibitor significantly blocked DC gelatinase activity and increased adherence of DC in a dose-dependent manner. AtRA-induced Mmp-9 gene expression in DC was blocked by transcriptional inhibition. Because the Mmp-9 promoter contains no canonical retinoic acid response element (RARE), we performed additional studies to determine how atRA regulated DC Mmp-9 transcription. Electrophoretic mobility shift assays for the consensus Sp1, activating protein-1, and nuclear factor-kappaB binding sites located in the Mmp-9 promoter did not indicate greater nuclear protein binding in response to atRA. Chromatin immunoprecipitation assays indicated RARalpha and histone acetyltransferase p300 recruitment to, and acetylation of, histone H3 at the Mmp-9 promoter was greater after atRA treatment. These data suggest that atRA regulated DC adhesion in vitro partly through MMP-9 gelatinase activity. Mmp-9 expression was enhanced through a transcriptional mechanism involving greater RARalpha promoter binding, recruitment of p300, and subsequent histone H3 acetylation, despite the absence of a consensus RARE.
髓样树突状细胞（DC）是一种专门的抗原呈递免疫细胞。在外周组织中激活后，DC 迁移到淋巴结以激活 T 淋巴细胞。基质金属蛋白酶（MMP）-9 是 DC 迁移所必需的明胶酶。我们之前已经表明，全反式视黄酸（atRA），维生素 A 的生物活性代谢物，可显著增加 DC 的 MMP-9 mRNA 和蛋白产物。我们研究了 atRA 在体外增加 MMP-9 活性的机制。与用视黄酸受体（RAR）-α拮抗剂培养的细胞相比，用 atRA 培养的小鼠髓样 DC 表现出更高的明胶酶活性。添加 MMP-9 抑制剂可显著阻断 DC 明胶酶活性，并以剂量依赖性方式增加 DC 的黏附。转录抑制阻断了 atRA 诱导的 DC 中 Mmp-9 基因表达。由于 Mmp-9 启动子中没有典型的视黄酸反应元件（RARE），我们进行了进一步的研究以确定 atRA 如何调节 DC Mmp-9 转录。位于 Mmp-9 启动子中的共识 Sp1、激活蛋白-1 和核因子-κB 结合位点的电泳迁移率变动分析表明，atRA 反应时没有更多的核蛋白结合。染色质免疫沉淀分析表明，RARalpha 和组蛋白乙酰转移酶 p300 募集到 atRA 处理后 Mmp-9 启动子，并乙酰化组蛋白 H3。这些数据表明，atRA 部分通过 MMP-9 明胶酶活性调节 DC 体外黏附。通过涉及更大的 RARalpha 启动子结合、p300 募集以及随后的组蛋白 H3 乙酰化的转录机制增强了 Mmp-9 表达，尽管缺乏共识 RARE。
