AP1-dependent regulation of bone mass and energy expenditure in the hypothalamus

描述(申请人提供)：该项目基于最近获得的数据，证明了FosB和其他对FosB和AP1转录机制的拮抗剂在中枢神经系统中一方面调节骨形成，另一方面调节能量消耗和脂肪的作用。我们已经部分地探索了过度表达的小鼠的骨骼和脂肪表型之间的联系(FosB(Kveiborg等人，2004年；Sabatakos等人，2000年)。然而，我们最近的两项研究，一项是上个月发表的(Rowe等人，2009年)，另一项正在准备提交(见附录ASBMR摘要，2009)，已经产生了一些非常令人兴奋的新数据，在我们看来，这些数据值得进一步研究，并可能导致高度创新的发现，不仅对骨质疏松症，而且对肥胖和糖尿病都有重大影响。简而言之，第一项研究表明，具有高骨量的ENO2-(FosB)小鼠表现出能量消耗的增加，导致脂肪细胞大小减少，从而减少脂肪质量。这与胰岛素水平降低、胰岛素敏感性增加和更好的葡萄糖耐量有关。由于靶向(FosB到脂肪细胞)不能模拟表型，我们随后转向能量的中央调节。在第二项研究中，在下丘脑腹侧部分靶向表达(FosB或构建的AP1拮抗剂(显性负Jund))的小鼠概括了在ENO2启动子控制下过度表达的小鼠的整个表型(FosB)，导致能量消耗增加，体力活动减少，脂肪质量减少，骨形成和骨量显著增加。因此，这项应用的特定目的是确定受下丘脑(FosB或工程化DNJunD)转录因子家族拮抗剂(FosB或DNJunD)影响的神经元回路(FosB或DNJunD)，这些转录因子可导致强烈的骨形成诱导，从而增加能量消耗和随后减少脂肪质量。因此，本申请中提出的实验可能导致发现调控骨形成的新途径和药物发现的新靶点，可能为骨质疏松症的合成代谢治疗干预提供新的方法，但也可能对肥胖和糖尿病的病理生理学有所了解。

DESCRIPTION (provided by applicant): This project is based on recently acquired data demonstrating a role for (FosB and other antagonists to FosB and the AP1 transcriptional machinery in the central nervous system to regulate on the one hand bone formation and on the other hand energy expenditure and fat. We had partially explored the link between the bone and fat phenotypes of mice overexpressing (FosB (Kveiborg et al., 2004; Sabatakos et al., 2000). However, two of our recent studies, one published last month (Rowe et al., 2009) and one being prepared for submission (see Appendix ASBMR Abstract, 2009), have generated some very exciting new data which in our view deserve further investigation and could lead to highly innovative findings with significant implications not only in osteoporosis but also in obesity and diabetes. Briefly, the first study demonstrated that ENO2-(FosB mice, which have high bone mass, exhibited an increase in energy expenditure leading to a decrease in adipocyte size and thereby fat mass. This was associated with decreased insulin levels, increased insulin sensitivity and better glucose tolerance. Since targeting (FosB to adipocytes failed to mimic the phenotype, we then turned to the central regulation of energy. In the second study, targeted expression of (FosB or a constructed AP1 antagonist (Dominant Negative JunD) in the ventral portion of the hypothalamus recapitulated the entire phenotype of mice overexpressing (FosB under the control of the ENO2 promoter, inducing an increase in energy expenditure, decreased physical activity, decreased fat mass and markedly increased bone formation and bone mass. The Specific Aim of this application are therefore to identify the neuronal circuit(s) affected by the hypothalamic expression of (FosB (or engineered DNJunD), antagonists of the AP1 family of transcription factors, which lead to strong induction of bone formation with an increase in energy expenditure and a subsequent reduction in fat mass. The experiments proposed in this application could therefore lead to the identification of novel pathways regulating bone formation and novel targets for drug discovery, potentially allowing new approaches for anabolic therapeutic intervention in osteoporosis, but could also shed some light on the pathophysiology of Obesity and Diabetes.