Role of Wnt in White and Brown Adipose Development

描述（由申请人提供）：我的长期研究目标是确定细胞外信号调节脂肪细胞分化和代谢的分子机制。我们率先研究了Wnt信号作为一种有效的内源性脂肪生成抑制剂的作用。Wnt10b作为一个脂肪生成开关，必须关闭它才能使培养的前脂肪细胞模型在体外分化。基于Wnt10b在细胞培养中白色脂肪形成中的作用，我们假设Wntl0b在生物体的综合环境中也调节白色脂肪组织（WAT）和棕色脂肪组织（BAT）的发育。为了验证这一假设，我们创建了转基因小鼠，其中Wnt10b在脂肪细胞特异性启动子422/aP2的控制下表达。我们的初步数据表明，Wnt10b转基因小鼠几乎不含WAT。除了对WAT的发育有影响外，我们的数据表明Wnt10b还抑制小鼠和培养细胞模型中棕色脂肪细胞的发育。由于对BAT发育的调控知之甚少，我们的研究将对我们了解这一重要的代谢和产热组织具有开创性意义。我们还将在Wnt10b -/-小鼠中探讨Wnt10b在脂肪组织发育中的作用。因此，本提案的具体目的是：1)研究Wnt10b在WAT发展中的作用。实验包括Wnt10b调控脂肪细胞分化和代谢的分子和机制分析。1)研究Wnt10b在BAT发生中的作用。实验包括Wnt 10b如何调节BAT在体内的发育和培养细胞中的棕色脂肪形成的分子和机制分析。1)确定Wnt10b对能量平衡的影响。测量的变量包括食物摄入量、体重增加、身体组成、代谢率、呼吸商、运动活动和体温。当对照组和Wnt转基因或无基因小鼠适应禁食、冷应激、遗传或饮食引起的肥胖时，将确定对能量平衡的影响。了解Wnt信号在WAT和BAT发展中的作用，将为肥胖症和II型糖尿病的医学问题提供重要的见解，这是美国两大健康风险。Wnt10b作为小鼠WAT发育异常的易感基因的鉴定将为Wnt10b在人类脂肪组织的正常和病理发育中发挥重要作用提供原理证明。

DESCRIPTION (provided by applicant): The long-term goal of my research program is to determine the molecular mechanisms by which extracellular signals regulate adipocyte differentiation and metabolism. We have pioneered investigations into the role of Wnt signaling as a potent, endogenously produced inhibitor of adipogenesis. Wnt10b acts as an adipogenic switch, which must be shut off for cultured preadipocyte models to differentiate in vitro. Based on the role of Wnt10b in white adipogenesis in cell culture, we hypothesize that Wntl0b also regulates development of white adipose tissue (WAT) and brown adipose tissue (BAT) in the integrative setting of the organism. To test this hypothesis, we have created transgenic mice in which Wnt10b is expressed under control of the adipocyte-specific promoter, 422/aP2. Our preliminary data indicate that Wnt10b transgenic mice are almost devoid of WAT. In addition to its effects on development of WAT, our data suggest that Wnt10b also inhibits development of brown adipocytes within mice and within cultured cell models. Because little is known about the regulation of BAT development, our studies will be seminal to our understanding of this important metabolic and thermogenic tissue. The role of Wnt10b in development of adipose tissues will also be explored in Wnt10b -/- mice. Thus, the Specific Aims of this proposal are to:1) Investigate the role of Wnt10b in development of WAT. Experiments include molecular and mechanistic analyses of how Wnt10b regulates adipocyte differentiation and metabolism,1) Investigate the role of Wnt10b in development of BAT. Experiments include molecular and mechanistic analyses of how Wnt 10b regulates BAT development in vivo and brown adipogenesis in cultured cells.1) Determine effects of Wnt10b on energy balance. Variables measured will include food intake, weight gain, body composition, metabolic rate, respiratory quotient, locomotor activity, and body temperature. Effects on energy balance will be determined as control and Wnt transgenic or null mice adapt to fasting, cold stress, genetic or diet-induced obesity.Understanding the role of Wnt signaling in the development of WAT and BAT will provide important insight into the medical problems of obesity and type II diabetes, two major health risks in the United States. The identification of Wnt10b as a susceptibility gene for dysregulated development of WAT in mice will provide proof of principle that Wnt10b is important for normal and pathological development of adipose tissue in the human population.