Regulation of brown and beige adipocyte development through Ebf2

描述(申请人提供)：在美国，肥胖是导致慢性病和过早死亡的主要原因。减少肥胖和糖尿病的一个有希望的方法是增加被称为棕色和米色脂肪细胞的能量消耗脂肪细胞的数量和/或功能。相反，棕色/米色脂肪活动减少可能使一些人更容易患上2型糖尿病和肥胖症。因此，研究这些细胞类型的发育和功能是至关重要的。成人组织中的棕色和米色脂肪细胞是由称为前体脂肪细胞的固定前体细胞产生的。然而，调控前脂肪细胞承诺或身份的分子途径尚不清楚。在这个项目中，我们将确定转录因子早期B细胞因子-2(Ebf2)在棕色脂肪谱系承诺中的作用，并评估脂肪组织中Ebf2的激活是否可以保护动物免受肥胖和代谢性疾病的影响。棕色脂肪、骨骼肌、真皮和一些白色脂肪细胞起源于胚胎中称为体节的多潜能中胚层结构。Ebf2是棕色和米色脂肪发育所必需的，它的表达识别体节中固定的棕色脂肪前体脂肪细胞，比任何棕色脂肪分化的迹象早几天。我们假设，Ebf2的表达使多能干细胞在体节中遭受棕色脂肪专一性的命运。为了研究这一点，我们将确定Ebf2在Somit来源的干细胞中的表达是否将它们转化为棕色前脂肪细胞，并评估前脂肪细胞中Ebf2或其某些下游靶基因的缺失是否激活了不同的细胞命运。谱系追踪将被用来评估体内表达Ebf2的细胞的命运。EBF2在脂肪细胞中启动了一个完整的棕色脂肪特异性程序，但其作用机制或生理效应尚未阐明。我们假设Ebf2与前脂肪细胞中的棕色脂肪特异性基因结合，并使这些部位的染色质有能力与脂肪细胞中的其他转录激活因子结合。为了检验这一点，我们将分析Ebf2与其他关键因素的结合，PPAR？和c/eBP�，在野生型和ebf2缺陷的前脂肪细胞分化过程中。鉴于Ebf2的表达强烈促进棕色和米色脂肪的分化，我们假设脂肪组织中Ebf2的激活抑制了代谢性疾病。为了测试这一点，我们将分析在脂肪组织中异位表达Ebf2的小鼠的系统代谢，并建立一个小鼠模型来研究Ebf2是否能在成年人中准确地诱导Wat褐变。综上所述，这些研究将为干细胞如何经历棕色脂肪谱系承诺提供关键的见解。了解Ebf2如何在棕色/米色脂肪承诺中发挥作用，对于设计增加棕色/米色脂肪质量以达到治疗效果的方法至关重要。

DESCRIPTION (provided by applicant): Obesity is a leading cause of chronic illness and premature death in the U.S. A promising avenue to reduce obesity and diabetes is through increasing the amount and/or function of energy-dissipating fat cells, called brown and beige adipocytes. Conversely, reduced brown/beige fat activity may predispose some people to type 2 diabetes and obesity. It is thus critical to study how these cell types develop and function. Brown and beige fat cells in adult tissues arise from committed precursor cells called preadipocytes. However, the molecular pathways that regulate preadipocyte commitment or identity are unknown. In this project, we will determine the function of Early B Cell Factor-2 (Ebf2), a transcription factor, in brown fat-lineage commitment and evaluate whether activation of Ebf2 in fat tissue protects animals against obesity and metabolic disease. Brown fat, skeletal muscle, dermis and some white fat cells originate from multipotent mesodermal structures in the embryo called somites. Ebf2 is required for brown and beige fat development and its expression identifies committed brown fat preadipocytes in somites, days before any sign of brown fat differentiation. We hypothesize that Ebf2 expression commits multipotent stem cells to a brown fat-specific fate in somites. To investigate this, we will determine if expression of Ebf2 in somit- derived stem cells converts them into brown preadipocytes and assess whether loss of Ebf2 or certain of its downstream target genes in preadipocytes activates alternative cell fates. Lineage tracing will be used to assess the fate of Ebf2-expressing cells in vivo. Ebf2 turns on a complete brown fat-specific program in adipocytes, but its mechanism of action or physiological effects have not been clarified. We hypothesize that Ebf2 binds to brown fat-specific genes in preadipocytes and makes the chromatin at these sites competent for the binding of other transcriptional activators in adipocytes. To test this, we will analyze the binding of Ebf2 and other key factors, Ppar? and c/EBP�, during the differentiation of wildtype and Ebf2-deficient preadipocytes. Given that Ebf2 expression strongly promotes brown and beige fat differentiation, we hypothesize that activation of Ebf2 in adipose tissue suppresses metabolic disease. To test this, we will analyze the systemic metabolism of mice that ectopically express Ebf2 in adipose tissue and develop a mouse model to investigate whether Ebf2 can acutely induce WAT browning in adults. Taken together, these studies will provide critical insights into how stem cells undergo brown fat lineage commitment. Understanding how Ebf2 functions in brown/beige fat commitment will be crucial for designing approaches to increase brown/beige fat mass for therapeutic effect.