Diabetic Fracture Healing

描述(由申请人提供)：摘要糖尿病导致骨量减少和骨折风险增加。此外，糖尿病还会干扰下颌骨和长骨的骨折修复。我们最近发现，正常血糖和糖尿病小鼠之间的一个主要区别是糖尿病组软骨加速丧失。这表明糖尿病骨折愈合过程中存在一种以前未被发现的分解代谢缺陷，提示快速去除软骨可能会减少软骨内骨形成的原基。此外，糖尿病骨折骨痂的特征是软骨细胞中FOXO1活性水平显著升高和FOXO1核移位增加。这项拟议研究的目的是验证这样一种假设，即糖尿病增强的FOXO1活性改变了软骨细胞中的基因表达，从而有助于糖尿病骨折的受损愈合。目的1研究糖尿病骨折愈合、肿瘤坏死因子-1升高、晚期糖基化终末产物或高糖水平等条件刺激软骨细胞FOXO1活化的机制。这些实验将对FOXO1翻译后修饰进行质谱学评估，这一点具有重要意义，因为它调节了FOXO1的核定位和DNA结合活性。目的2利用CRE/LOX系统确定软骨细胞特异性缺失FOXO1是否会逆转糖尿病对加速去除软骨的影响。为了研究FOXO1如何影响愈合过程，我们将检测FOXO1缺失对破骨细胞前基因表达、破骨细胞数量和机械强度的影响。目的3将利用相同的小鼠来确定软骨细胞中FOXO1的条件缺失是否逆转了糖尿病骨折愈合过程中增强的软骨细胞凋亡和促凋亡基因的表达。 公共卫生相关性：叙述性糖尿病导致骨量减少和骨折风险增加。此外，糖尿病还会干扰下颌骨和长骨的骨折修复。我们最近发现，正常血糖和糖尿病小鼠之间的一个主要区别是糖尿病组软骨加速丧失。这表明糖尿病骨折愈合过程中存在一种以前未被发现的分解代谢缺陷，提示快速去除软骨可能会减少软骨内骨形成的原基。此外，糖尿病骨折骨痂的特征是转录因子FOXO1水平显著升高，以及软骨细胞中FOXO1核转位增加。这项研究的目的是验证一种假说，即糖尿病通过增强FOXO1的激活来改变软骨细胞中促破骨细胞生成和促凋亡基因的表达，从而导致糖尿病骨折愈合受损。

DESCRIPTION (provided by applicant): Abstract Diabetes causes osteopenia and increased fracture risk. Furthermore, diabetes interferes with fracture repair of the mandible and long bones. We have recently found that a major difference between normoglycemic and diabetic mice is the accelerated loss of cartilage in the diabetic group. This points to a previously unrecognized catabolic defect in diabetic fracture healing and suggests that rapid removal of cartilage may reduce the anlage for endochondral bone formation. Furthermore, diabetic fracture calluses are characterized by significantly elevated levels of FOXO1 activity and increased FOXO1 nuclear translocation in chondrocytes. The goal of the proposed studies is to test the hypothesis that diabetes enhanced FOXO1 activity alters gene expression in chondrocytes that contributes to impaired diabetic fracture healing. Aim 1 will investigate mechanisms by which conditions that are present in diabetic fracture healing, elevated TNF-1, advanced glycation end products or high glucose levels stimulate FOXO1 activation in chondrogenic cells. These experiments will FOXO1 post- translational modification assesses by mass spectrometry which is significant since it regulates FOXO1 nuclear localization and DNA binding activity. Aim 2 will establish whether chondrocyte specific deletion of FOXO1 using the Cre/lox system will reverse the impact of diabetes on the accelerated removal of cartilage. To investigate how FOXO1 could affect the healing process we will examine FOXO1 deletion on pro- osteoclastogenic gene expression, osteoclast numbers and mechanical strength. Aim 3 will utilize the same mice to determine whether conditional deletion of FOXO1 in chondrocytes reverses diabetes enhanced chondrocyte apoptosis and pro-apoptotic gene expression during diabetic fracture healing. PUBLIC HEALTH RELEVANCE: Narrative Diabetes causes osteopenia and increased fracture risk. Furthermore, diabetes interferes with fracture repair of the mandible and long bones. We have recently found that a major difference between normoglycemic and diabetic mice is the accelerated loss of cartilage in the diabetic group. This points to a previously unrecognized catabolic defect in diabetic fracture healing and suggests that rapid removal of cartilage may reduce the anlage for endochondral bone formation. Furthermore, diabetic fracture calluses are characterized by significantly elevated levels of the transcription factor FOXO1 and increased FOXO1 nuclear translocation in chondrocytes. The goal of the proposed studies is to test the hypothesis that diabetes alters pro-osteoclastogenic and pro- apoptotic gene expression in chondrocytes that contributes to impaired diabetic fracture healing through a mechanism mediated by enhanced activation of FOXO1.