Role of TLE3 in the 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编程以采用其储存或燃烧能量的独特表型特征的理解存在差距。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用于外周组织消耗，而棕色脂肪细胞在冷暴露期间储存和燃烧能量以产生热量。米色脂肪细胞的行为与棕色脂肪细胞相似，但在长时间冷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是如何被编程以采用这些不同的表型特征的。最终，我们的目标是将能源平衡从储存转向支出。我们已经确定了相反的转录程序，区分能量储存和消耗。我们有证据支持TLE 3和Prdm 16相互对抗。我们的假设是，TLE 3直接与Prdm 16相互作用，形成相互中和的辅激活因子复合物，以调节能量储存或消耗。其中结合的TLE 3-Prdm 16复合物是无活性的，并且未结合的TLE 3或Prdm 16自由地与PPARγ相互作用以分别刺激能量储存或能量消耗。我们预计这种相互作用在TLE 3和Prdm 16表达高的米色脂肪细胞中将是最重要的。此外，我们已经确定了一个冷诱导因子，AES，我们假设与TLE 3相互作用，破坏TLE 3/Prdm 16复合物。在强有力的初步数据的指导下，该假设将在以下目标中进行测试：Aim 1将确定TLE 3-Prdm 16相互作用的功能意义，Aim 2将确定TLE 3是否阻断米色脂肪细胞的出现，Aim 3将测试AES是否通过破坏TLE 3和Prdm 16之间的相互作用来刺激米色脂肪细胞的出现。在Aim 1下，我们设计了几个TLE 3和Prdm 16缺失，以定位介导TLE 3-Prdm 16相互作用的结构域，并开发了一种酵母双杂交系统，以鉴定破坏TLE 3-Prdm 16界面的点突变，同时保持与PPARγ的完整相互作用。这些实验将使我们能够测试TLE 3-Prdm 16相互作用在米色脂肪细胞中的生物学意义。在Aim 2下，我们将利用我们独特的功能获得和丧失小鼠模型来测试TLE 3是否阻断皮下脂肪组织中冷诱导的米色细胞外观。在Aim 3下，使用脂肪细胞中AES有条件缺失的小鼠，我们将测试棕色或米色脂肪细胞的编程是否需要AES。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，以编程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 prolonged 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. We have identified opposing transcriptional programs that distinguish between energy storage and expenditure. We have evidence that supports that 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 PPARγ 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. Furthermore, we've identified a cold inducible factor, AES, that we hypothesize interacts with TLE3 to disrupt the TLE3/Prdm16 complex. Guided by strong preliminary data, this hypothesis will be tested in the following aims: Aim1 will determine the functional significance of the TLE3- Prdm16 interaction, Aim2 will determine whether TLE3 blocks the appearance of beige adipocytes, and Aim3 will test whether AES stimulates the appearance of beige adipocytes by disrupting the interaction between TLE3 and Prdm16. 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 disrupt the TLE3-Prdm16 interface, while maintaining intact interactions with PPARγ. These experiments will allow us to test the biological significance of the TLE3-Prdm16 interaction in beige adipocytes. 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. Under Aim3, using mice with conditional deletion of AES in adipocytes, we will test whether AES is required for programming of brown or beige adipocytes. 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.