MAF1 Function and Metabolic Inefficiency

项目摘要 MAF1是一种保守的营养和胁迫敏感的基因转录抑制因子。最出名的是其 作为酵母中RNA聚合酶III转录的主要调节者，MAF1也被证明影响 RNA聚合酶II转录的精选基因在哺乳动物细胞中的表达。MAF1基因的抑制作用 RNA聚合酶III调节转移RNA、5S rRNA和其他丰富的非编码RNA的合成 它们加在一起占每个细胞总RNA的15%。因此，MAF1功能被认为对 新陈代谢经济。最近对这一观点的戏剧性证明是因为发现老鼠有一个完整的 身体敲除Maf1基因的人很瘦，对饮食引起的肥胖和非酒精性脂肪肝有很强的抵抗力 疾病。Maf1 KO小鼠代谢效率低下，能量消耗增加，并有较长的 寿命表明健康状况有所改善。目前的理解是，增加的RNA PolIII转录 每个组织都对能量昂贵的核苷酸合成提出了这样的要求，以至于它改变了 能源利用和储存之间的平衡。因此，这个项目的长期目标是确定如何 MAF1的缺失会改变基因表达和代谢，从而改变代谢效率和能量 支出。这项提案的目的一将研究关键代谢中的基因表达是如何改变的 通过转录组和核糖体图谱以及通过研究tRNA群体对Maf1/-小鼠组织的影响 翻译效率和保真度。AIM II将确定能量增加背后的代谢变化 Maf1-/-小鼠通过靶向代谢物图谱的消耗。这些研究将集中在中枢代谢方面 途径，并将补充稳定的同位素测量的全身脂肪分解和通量通过 磷酸戊糖途径，我们假设的过程与增加的供应和 小鼠体内代谢能量的消耗。AIM III将研究RNA PolIII转录在 通过高度丰富的非编码蛋白的自由合成来驱动MAF1-/-小鼠的能量消耗 RNA，包括转移RNA和非特异性转录。新生的延长的文字记录测序将 在全基因组范围内定位和量化RNA PolIII分子，并将创建一种新的小鼠模型来抑制 Maf1 KO表型，直接或间接由RNAPolIII转录升高所致。最后，研究 在Aim IV中，将确定在幼年和成年小鼠中，MAF1的丢失是否通过诱导的和系统性的CRE- 介导性重组会增加代谢效率。这些实验预计将支持 MAF1的出生后功能对代谢经济至关重要，同时提供了一种强大的 MAF1作为减肥药物靶点的潜力展示。

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.