Neurobiological control of periodontal homeostasis through microRNA, TGF-beta, and Wnt signaling

牙周组织是一种神经丰富的组织，通过以下方式进行持续的建模和重塑 牙槽骨成骨细胞、骨细胞和破骨细胞。我们实验室的研究表明， 三叉神经节与马氏上皮支的密切空间关系 位于非矿化牙周韧带内的上皮细胞网络。下牙槽神经(Ian) 导致牙本质牙槽僵硬和ERM减少的横断研究证实， 感觉神经在牙周动态平衡中的重要作用。对于本应用程序，我们有 建立了本实验室的Ian横断面模型，并提供了增强的影像证据 大鼠磨牙牙周区矿化和强直。基因表达谱比较 Ian横切组织和对照组织显示甘丙素意外显著增加28倍 (GAL)和转化生长因子-β信号分子Smad2、Smad3和转化生长因子-β1的两倍以上的减少， WnT抑制剂DKK1、DKK2和GSK-3β。在同一Ian横断组中，microRNA miR-92b 通过miRNA图谱和RT-PCR验证，表达上调了两倍以上。MIR-92b 结合生物信息学数据提示Wnt和转化生长因子-βAS的Ian横切后表达上调 可能的miR-92b靶点促使我们推测GAL影响其骨骼生成的下游效应 通过miR-92b。体外研究表明，Gal处理促进了PDL的成骨分化 增加骨髓基质细胞的矿化，同时减少破骨细胞的生成。RhoA区块或 GAL拮抗剂的应用影响了PDL的细胞骨架组织和基因表达，提示 GAL通过G蛋白偶联受体发挥作用。当I应用于动物的牙周袋时 患有牙周炎的GAL组织工程结构使牙槽骨增加了20% 与对照组相比，牙槽骨高度在临床上有显著增加。基座 在这组有希望的新数据上，我们设计了一项研究计划，以确定GAL在反应中的作用 Ian横切术，确定其影响骨骼形成的潜在机制，并开发其 适用于骨再生和预防牙周强直。我们的总体目标是 研究计划是验证牙周神经影响牙槽骨内稳态的假设 通过GAL-GPCRmiR-92b-转化生长因子-β/WNT调控环和GAL应用 神经分泌肽将刺激Wnt信号和新骨形成。我们预计， 我们的研究结果将导致创新的基于神经肽的/工程杂交方法，将 恢复数百万患者的牙周健康，防止相关的情感和功能疤痕 牙齿脱落，牙齿残缺不全。

The periodontium is a richly innervated tissue that undergoes continuous modelling and remodeling by alveolar bone osteoblasts, osteocytes, and osteoclasts. Studies from our laboratory have demonstrated a close spatial relationship between trigeminal nerve ganglia and the Epithelial Rests of Malassez (ERM), an epithelial cell network residing within the non-mineralized periodontal ligament. Inferior alveolar nerve (IAN) transection studies resulting in dento-alveolar ankylosis and a reduction in ERM have confirmed the essential role of sensory innervation for periodontal homeostasis. For the present application, we have established the IAN transection model in our laboratory and provided radiographic evidence for enhanced mineralization and ankylosis in the periodontal region of rat molars. Gene expression profiling comparing IAN transected and control tissues demonstrated an unexpected 28-fold significant increase in galanin (GAL) and a more than two-fold decrease in the TGF-β signaling molecules Smad2, Smad3 and Tgf-β1, and the Wnt inhibitors Dkk1, Dkk2 and Gsk-3β. In the same IAN transection group, microRNA miR-92b expression was more than two-fold upregulated, as verified via miRNA profiling and RT-PCR. MiR-92b upregulation after IAN transection in conjunction with bioinformatics data implicating Wnt and Tgf-β as possible miR-92b targets prompted us to speculate that GAL affects its skeletogenic downstream effects through miR-92b. In vitro studies revealed that GAL treatment promoted osteogenic differentiation of PDL progenitors and increased mineralization, while reducing osteoclastogenesis of BMMCs. Block of RhoA or application of GAL antagonist affected PDL cytoskeletal organization and gene expression, indicating that GAL functions through G protein coupled receptors. IWhen applied to periodontal pockets of animals suffering from periodontitis, GAL tissue engineering constructs accomplished a 20% increase in alveolar bone levels compared to controls, resulting in a clinically significant increase in alveolar bone height. Based on this promising new set of data we have designed a research plan to define the role of GAL in response to IAN transection, determine the mechanism underlying its effect on skeletogenesis, and exploit its applicability for bone regeneration and the prevention of periodontal ankylosis. The overall goal of our research plan is to test the hypothesis that periodontal nerves affect alveolar bone homeostasis through a GAL–GPCR–miR-92b–TGF-β/Wnt regulatory loop and that application of GAL neurosecretory peptides will stimulate Wnt signaling and new bone formation. We anticipate that the outcomes of our study will lead to innovative neuropeptide based/engineering hybrid approaches that will restore periodontal health in millions of patients and prevent the emotional and functional scars associated with lost teeth and incomplete dentitions.