Transcriptional regulation of beige adipocytes

描述（由申请人提供）：我们对白色、棕色和米色脂肪细胞亚型如何被编程以采用其独特的储存或燃烧能量的表型特征的理解存在空白。能量摄入和消耗之间的不平衡会导致肥胖和代谢紊乱，如2型糖尿病。白色脂肪细胞储存和调动能量供外周组织消耗，而棕色脂肪细胞在冷暴露时储存和燃烧能量以产生热量。米色脂肪细胞表现与棕色脂肪细胞相似，但在长期低温暴露下出现在白色脂肪组织中。我们的长期目标是更好地了解脂肪细胞前体如何被编程以采用这些不同的表型特征。我们的最终目标是将能量平衡从储存转变为消耗。为此，我们在完成KO1奖中描述的研究方面取得了重大进展，我们确定了TLE3和Prdm16分别驱动相反的转录程序来刺激白色或棕色脂肪基因表达。在这个RO3应用中，我们将扩展KO1奖项的研究结果，以获得对TLE3和Prdm16如何相互作用的分子理解。我们的假设是，TLE3直接与Prdm16相互作用，形成相互中和的辅激活物复合物，以调节能量储存或消耗。其中结合的TLE3-Prdm16复合物是无活性的，未结合的TLE3或Prdm16可以自由地与PPAR¿相互作用，分别刺激能量储存或能量消耗。我们预计这种相互作用在棕色脂肪细胞中最为重要，因为棕色脂肪细胞中TLE3和Prdm16的表达较高。在强有力的初步数据的指导下，这一假设将在Aim1中进行检验，我们将确定TLE3- prdm16相互作用的功能意义，在Aim2中，我们将确定TLE3是否阻断了米色脂肪细胞的外观。在Aim1下，我们设计了几个TLE3和Prdm16缺失来绘制介导TLE3-Prdm16相互作用的结构域，并开发了一个酵母-双杂交系统来识别点突变，这将使我们能够测试TLE3-Prdm16相互作用的生物学意义。在Aim2下，我们将利用我们独特的功能增益和功能丧失小鼠模型来测试TLE3是否阻断皮下脂肪组织中冷诱导的米色细胞外观。了解区分脂肪细胞亚型的转录机制将是确定新的治疗靶点的关键，从而使细胞采用有利的棕色/米色脂肪细胞表型来治疗肥胖。

DESCRIPTION (provided by applicant): There is a gap in our understanding of how the white, brown, and beige adipocyte subtypes are programmed to adopt their distinct phenotypic characteristics of storing or burning energy. The imbalance between energy intake and expenditure can lead to obesity and metabolic disorders such as type 2 diabetes. White adipocytes store and mobilize energy for peripheral tissue consumption, while brown adipocytes store and burn energy during cold exposure to generate heat. Beige adipocytes behave like brown adipocytes, but appear in white adipose tissue with long-term cold exposure. Our long-term objective is to better understand how adipocyte precursors are programed to adopt these distinct phenotypic characteristics. Ultimately our goal is to shift the energy balance from storage to expenditure. To this end we have made significant progress in completing our studies described in the KO1 award where we have determined that TLE3 and Prdm16 drive opposing transcriptional programs to stimulate white or brown fat gene expression, respectively. In this RO3 application, we will extend our findings from the KO1 award to gain a molecular understanding of how TLE3 and Prdm16 counter each other's actions. Our hypothesis is that TLE3 directly interacts with Prdm16 to form a mutually neutralized coactivator complex to regulate energy storage or expenditure. Where a bound TLE3-Prdm16 complex is inactive, and unbound TLE3 or Prdm16 are free to interact with PPAR¿ to stimulate energy storage or energy expenditure, respectively. We expect that this interaction will be most important in beige adipocytes where TLE3 and Prdm16 expression is high. Guided by strong preliminary data, this hypothesis will be tested in Aim1 where we will determine the functional significance of the TLE3-Prdm16 interaction, and in Aim2 where we will determine whether TLE3 blocks the appearance of beige adipocytes. Under Aim1, we've engineered several TLE3 and Prdm16 deletions to map the domains that mediate the TLE3-Prdm16 interaction and have developed a yeast-two-hybrid system to identify point mutations that will allow us to test the biological significance of the TLE3-Prdm16 interaction. Under Aim2, we will utilize our unique gain and loss of function mouse models to test whether TLE3 blocks the cold-induced appearance of beige cells in subcutaneous adipose tissue. Understanding the transcriptional mechanisms that distinguish between the adipocyte subtypes will be key to identifying novel therapeutic targets to program cells to adopt the favorable brown/beige adipocyte phenotype to treat obesity.