Transcriptional Regulation of Osteoclasts by Mitf

Mitf 对破骨细胞的转录调控

• 批准号: 6936618
• 负责人: Yi-Ling Lin
• 金额: $ 13.5万
• 依托单位: UNIVERSITY OF KENTUCKY
• 依托单位国家: 美国
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-09-01 至 2007-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6936618
• 关键词: Adenoviridae; Retroviridae; biological signal transduction; cell growth regulation; dimer; embryo /fetus tissue /cell culture; enzyme activity; gene expression; genetic regulation; laboratory mouse; laboratory rat; microphthalmos; mitogen activated protein kinase; monoclonal antibody; mutant; osteoclasts; osteopetrosis; phosphorylation; protein kinase A; protein structure function; transcription factor; transfection /expression vector

Recent advances in bone biology have revolutionized dentistry. With better understanding of how osteoblasts respond to bone-forming signals, dentists now can use a variety of grafting materials to perform bone augmentation procedures and grow bone "de novo". In contrast, it is still largely unknown how osteoclasts regulate their activity in response to local factors. This knowledge is of great importance to the dental profession since so many dental diseases are directly or indirectly the result of unwanted osteoclast activation. One critical regulator of osteoclast activity is Microphthalmia transcription factor (Mitt). Mice carrying semidominant Mitf alleles exhibit various degrees of osteopetrosis, indicating Mitf is a promising tool for studying gene regulation in osteoclasts. The objective of the proposed study is to gain knowledge of the transcriptional regulation of osteoclasts by Mitf and three other family members, TFEB, TFEC and TFE3 (the four proteins form the "MiT" family). Since Mitf semidominant mutant mice exhibit an age-dependent phenotype, the chronological expression profiles of MiT proteins during osteoclast development will be examined since this would be consistent with functional rescue of Mitf by family members. MAPK and Rsk/PKA have previously been demonstrated to phosphorylate Mitf in melanocytes, which resulting in Mitf activation. To examine if similar processes occur in osteoclasts, recombinant MiT mutant viruses carrying disrupted MAPK and Rsk/PKA phosphorylation sites will be used, and the resulting phenotypic changes will be analyzed. Mitf has been found to regulate cytoskeletal changes in response to maturation signals during fetal osteoclast fusion. Overexpression of the individual MiT protein in fetal mi/mi osteoclasts (which do not fuse or form multinucleated giant cells) will be tested for the ability to rescue the fusion defect. Since Mitf may affect multinucleate giant cell formation by regulating the expression of molecules essential for osteoclast fusion, candidates known to be essential for this process (such as vitronectin receptor and osteopontin) will be examined for their relationship with Mitf.

骨生物学的最新进展给牙科医学带来了革命性的变化。随着对成骨细胞对骨形成信号的反应有了更好的了解，牙医现在可以使用各种移植材料来执行骨增强程序并重新长出骨。相比之下，破骨细胞如何对局部因素做出反应来调节它们的活动在很大程度上仍然是未知的。这一知识对牙科行业非常重要，因为许多牙科疾病直接或间接地是不想要的破骨细胞激活的结果。破骨细胞活性的一个关键调节因子是小眼球转录因子(MITT)。携带半显性MITF等位基因的小鼠表现出不同程度的骨化病，表明MITF是研究破骨细胞基因调控的一种有前途的工具。这项研究的目的是了解MITF和另外三个家族成员TFEB、TFEC和TFE3(这四个蛋白构成MIT家族)对破骨细胞的转录调控。由于MITF半显性突变小鼠表现出与年龄相关的表型，因此我们将研究MIT蛋白在破骨细胞发育过程中的时序表达谱，因为这与家族成员对MITF的功能拯救是一致的。MAPK和RSK/PKA在黑素细胞中可以磷酸化MITF，从而激活MITF。为了检验破骨细胞中是否发生了类似的过程，将使用携带被破坏的MAPK和RSK/PKA磷酸化位点的重组MIT突变病毒，并分析由此产生的表型变化。已发现MITF在胎儿破骨细胞融合过程中调节细胞骨架的变化，以响应成熟信号。单个MIT蛋白在胎儿MI/MI破骨细胞(不融合或形成多核巨细胞)中的过度表达将被测试以确定拯救融合缺陷的能力。由于MITF可能通过调节破骨细胞融合所必需的分子的表达来影响多核巨细胞的形成，已知在这一过程中必不可少的候选分子(如Vitronectin受体和骨桥蛋白)将被检查它们与MITF的关系。