MAF1 Function and Metabolic Inefficiency

项目摘要 MAF1是一个保守的营养和压力敏感的基因转录抑制因子。最出名的是它的 作为酵母中RNA聚合酶III转录的主要调节因子，MAF1也显示出影响 哺乳动物细胞中RNA聚合酶II转录的选择基因的表达。MAF1抑制 RNA聚合酶III调节转运RNA、5S rRNA和其他丰富的非编码RNA的合成 它们共同占每个细胞中总RNA的约15%。因此，MAF1功能被认为是重要的 代谢经济。最近的一项发现为这一观点提供了戏剧性的证据， Maf 1的身体敲除是瘦的，并且对饮食诱导的肥胖和非酒精性脂肪肝具有深刻的抵抗力。 疾病Maf 1基因敲除小鼠代谢效率低下，能量消耗增加， 寿命表明健康状况得到改善。目前的理解是，增加的RNA聚合酶III转录， 每一种组织都对昂贵的核苷酸合成提出了这样的要求， 能源利用和储存的平衡。因此，本项目的长期目标是确定如何 MAF1的缺乏改变基因表达和代谢，从而改变代谢效率和能量 支出本提案的目的I将研究基因表达如何在关键代谢中被改变， 通过转录组和核糖体分析以及通过研究tRNA群体对Maf 1-/-小鼠组织的影响， 翻译效率和忠实度。目标二将确定增加的能量的代谢变化 Maf 1-/-小鼠通过靶向代谢物谱分析的消耗。这些研究将集中在中枢代谢 途径，并将通过全身脂解的稳定同位素测量和通过 戊糖磷酸途径，我们假设这些过程与供应增加有关， 消耗的代谢能量。目的III研究RNA聚合酶III转录在细胞凋亡中的作用。 Maf 1-/-小鼠通过无限制合成高丰度非编码蛋白来驱动能量消耗 RNA，包括转移RNA和非特异性转录。新生延长转录测序将 定位和定量RNA聚合酶III分子基因组范围内，并将建立一个新的小鼠模型，以抑制 Maf 1 KO表型直接或间接由RNA pol III转录升高引起。最后，研究 在目的IV中，将确定年轻和成年小鼠中MAF1的损失是否通过诱导型和系统性Cre- 介导的重组增加了代谢效率低下。预计这些实验将支持 MAF1的出生后功能对代谢经济至关重要，同时提供了强大的 这证明了MAF1作为抗肥胖药物靶标的潜力。

Project Summary MAF1 is a conserved nutrient- and stress-sensitive repressor of gene transcription. Best known for its role as a master regulator of RNA polymerase III transcription in yeast, MAF1 has also been shown to affect the expression of select genes transcribed by RNA polymerase II in mammalian cells. MAF1 repression of RNA polymerase III regulates the synthesis of transfer RNAs, 5S rRNA and other abundant non-coding RNAs that together account for ~15% of total RNA in every cell. Thus, MAF1 function is thought to be important for metabolic economy. Recent dramatic proof of this view was provided by the finding that mice with a whole body knockout of Maf1 are lean and profoundly resistant to diet-induced obesity and non-alcoholic fatty liver disease. Maf1 KO mice are metabolically inefficient, have increased energy expenditure and have an extended lifespan indicative of improved health. The current understanding is that increased RNA pol III transcription in every tissue places such a demand on the energetically expensive synthesis of nucleotides that it alters the balance between energy utilization and storage. Thus, the long term goal of this project is to determine how the absence of MAF1 changes gene expression and metabolism to alter metabolic efficiency and energy expenditure. Aim I of this proposal will examine how gene expression has been altered in key metabolic tissues of Maf1-/- mice by transcriptome and ribosome profiling and by investigating tRNA population effects on translation efficiency and fidelity. Aim II will determine the metabolic changes underlying the increased energy expenditure of Maf1-/- mice by targeted metabolite profiling. These studies will focus on central metabolic pathways and will be complemented by stable isotope measurements of whole body lipolysis and flux through the pentose phosphate pathway, processes that we hypothesize are associated with the enhanced supply and consumption of metabolic energy in the mice. Aim III will investigate the role of RNA pol III transcription in driving energy expenditure in Maf1-/- mice through unrestrained synthesis of highly abundant non-coding RNAs, including transfer RNA and non-specific transcription. Nascent elongating transcript sequencing will locate and quantify RNA pol III molecules genome-wide and a new mouse model will be created to suppress Maf1 KO phenotypes that result directly or indirectly from elevated RNA pol III transcription. Finally, the studies in aim IV will determine whether loss of MAF1 in young and adult mice via inducible and systemic Cre- mediated recombination increases metabolic inefficiency. These experiments are expected to support the concept that the postnatal function of MAF1 is critical for metabolic economy while providing a powerful demonstration of the potential of MAF1 as an anti-obesity drug target.