NIDCR Individual Predoctoral Scientist Fellowship

描述（由申请人提供）：慢性炎症性疾病如牙周病在糖尿病患者中大大加重（Wang and Kaltenboeck, 2010）。牙周炎加速的机制尚不清楚，然而，糖尿病和牙周炎都激活促炎转录因子NF-B。刺激后，NF-κB募集其他蛋白质，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。在本研究中，我们将研究在高糖条件（糖尿病）和脂多糖（LPS）挑战（牙周炎）下同时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，周围病变LPS攻击影响三组NF-kB靶基因，这些靶基因对应于独特的组蛋白甲基化特征：(1)与细胞募集相关的即时早期反应基因，如CCL2、CXCL1和IL-6，这些基因表现出活跃的H3K4me3甲基化；(2)与细胞激活和防御机制相关的晚期反应基因，如IL-1ß、TNF-α和几种具有抑制H3K9me3和/或H3K27me3甲基化的防御素；(3)参与骨和结缔组织代谢的基质相关基因，如胶原i和iii、MMP2和9。和RANKL被活性和抑制性三甲基化标记占据。我们认为，长期炎症严重改变了这些牙周结缔组织的甲基化状态，从而降低了其正常功能的能力，导致慢性牙周炎。因此，我们假设，在对周围病变LPS挑战和高糖条件的反应中，NF-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失调，这与糖尿病患者牙周炎加剧有关。因此，我们制定了一项研究计划：(1)在牙周炎的进展过程中，确定上述NF- kb靶基因组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表型恶化中的作用；(3)确定NF-κB信号传导、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，这可能导致糖尿病条件下牙周炎治疗策略的改进。

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.