NIDCR Individual Predoctoral Scientist Fellowship

描述(申请人提供)：慢性炎症性疾病，如牙周病，在糖尿病患者中严重恶化(Wang和Kaltenboeck，2010)。牙周炎加速的机制尚不清楚，但糖尿病和牙周炎都激活了促炎转录因子NF-B。在刺激下，NF-κB会招募其他蛋白质，如修饰酶。修饰酶通过组蛋白修饰机制改变染色质结构，最终调节转录。在这项研究中，我们将检测在高糖条件下(糖尿病)和脂多糖(LPS)攻击下(牙周炎)伴随表达的基因启动子的组蛋白甲基化。我们初步研究的微阵列基因表达分析显示，围病期脂多糖攻击影响三组与独特的组蛋白甲基化信号相对应的核因子-kB靶基因：(I)与细胞招募相关的即刻-早期反应基因，例如CCL2、CXCL1和IL-6，它们显示了活跃的H3K4me3甲基化；(Ii)与细胞激活和防御机制相关的晚期反应基因，如IL-1ü、肿瘤坏死因子-α，以及一些防御素，其特征是抑制H3K9me3和/或H3K27me3的甲基化；(Iii)与骨骼和结缔组织代谢有关的基质相关基因，如胶原蛋白I和III、MMP2和9，以及RANK1被活跃和抑制性的三甲基化标记所占据。我们认为，长期炎症会严重改变这些牙周结缔组织的甲基化状态，从而降低其正常功能的能力，从而导致慢性牙周炎。因此，我们假设，在应对围病期的内毒素攻击和高糖条件下，核因子-kB利用组蛋白甲基化机制，导致促炎基因上调和基质相关基因的失调，与糖尿病条件下加重的牙周炎有关。因此，我们制定了一项研究计划，以(1)确定上述几组NF-kB靶基因在牙周炎进展过程中的基因表达和表观遗传组蛋白甲基化模式，(2)确定NF-κB和染色质修饰在糖尿病动物牙周恶化表型中的作用，以及(3)确定NF-κB信号、染色质结构和组蛋白甲基化之间的关系。总之，这些实验将提供关于糖尿病和牙周炎之间功能联系的表观遗传学信息，这可能会导致糖尿病条件下牙周炎的治疗策略的改进。

DESCRIPTION (provided by applicant): Chronic inflammatory diseases such as periodontal disease are greatly exacerbated in diabetic patients (Wang and Kaltenboeck, 2010). The mechanism of the acceleration of periodontitis remains unknown, however, diabetes and periodontitis both activate the pro-inflammatory transcription factor NF-B. Upon stimulation, NF-κB recruits other proteins such as modification enzymes. Modification enzymes alter the chromatin structure via histone modification mechanisms ultimately regulating transcription. In the present study, we will examine histone methylation of gene promoters concomitantly expressed in high glucose conditions (diabetes) and under lipopolysaccharide (LPS) challenge (periodontitis). Microarray gene expression analysis from our preliminary study revealed that periopathic LPS challenge affects three groups of NF-kB target genes corresponding to unique histone methylation signature: (i) immediate-early response genes associated with cell recruitment such as CCL2, CXCL1,and IL-6 which demonstrated active H3K4me3 methylation (ii) late response genes associated with cell activation and defense mechanisms such as IL-1ß, TNF-α, and several defensins that featured repressive H3K9me3 and/or H3K27me3 methylation and (iii) matrix-related genes involved in bone and connective tissue metabolism such as collagens I and III, MMP2 and 9, and RANKL were occupied by both active and repressive trimethylation marks. We propose that long-term inflammation severely alters the methylation state of these periodontal connective tissues which diminishes its ability to function normally and results in chronic periodontitis. We thus hypothesize that in response to periopathic LPS challenge and high glucose conditions, NF-kB avails itself of the histone methylation machinery, resulting in upregulation of pro-inflammatory genes and dysregulation of matrix-related genes, linked to exacerbated periodontitis under diabetic conditions. We have therefore developed a research plan to (1) identify gene expression and epigenetic histone methylation patterns in the aforementioned groups of NF-kB target genes during the progression of periodontitis, (2) to determine the role of NF-κB and chromatin modifications in the exacerbated periodontal phenotype of diabetic animals, and (3) identify the relationship between NF-κB signaling, chromatin structure and histone methylation. Together, these experiments will provide epigenetic information about functional links between diabetes and periodontitis which may result in improvements in therapeutic strategies for periodontitis under diabetic conditions.