Nutrient Regulation of Cell Physiology by O-GlcNAcylation

N-乙酰葡糖胺在细胞核、细胞质和细胞质的Ser（Thr）残基（O-GlcNAc化）上的循环 线粒体蛋白质作为营养传感器调节信号传导、转录和细胞内的蛋白质。 physiology.异常的O-GlcNAc酰化是糖尿病、癌症和阿尔茨海默病的病因学基础。 O-GlcNAcylation几乎调节转录的各个方面，包括RNA聚合酶II、组蛋白、DNA 甲基转移酶和几乎所有的转录因子。但我们对这些机制知之甚少 涉案TATA结合蛋白（TBP）是转录过程中最重要的组成部分之一 机械.我们最近的研究表明，TBP的调节O-GlcNAc酰基化响应营养。 O-GlcNAc化与蛋白质磷酸化和其他修饰具有广泛的串扰。然而，在这方面， 与磷酸化不同，磷酸化由数百种激酶催化，只有一种高度保守的基因， 编码O-GlcNAc转移酶（OGT）。尽管如此，OGT位点特异性地修饰了数千种蛋白质。 我们的数据表明，OGT的底物特异性不仅取决于其对肽的特异性 序列，但也通过其与其他蛋白质的瞬时关联，这些蛋白质动态地将其靶向特定的 印刷受体. OGT的靶向相互作用主要由其三肽重复序列（TPR）介导。OGT 缺失的TPR对小肽保持活性，但对全长蛋白质具有差的活性。 在此，我们将研究与O-GlcNAc酰化相关的两个主要问题： 研究TATA结合蛋白（TBP）通过O-GlcNAc酰化对葡萄糖的调节。假设：在 在某些启动子中，葡萄糖调节TBP DNA结合及其通过改变DNA的O-末端而弯曲DNA的能力。 GlcNAc酰化。我们将系统地阐明TBP的营养调控机制和功能。 三个进球：A。O-GlcNAc酰化在TBP分子和细胞特性中的作用？B。O的作用- GlcNAc在TBP转录周期中的相互作用。C. O-GlcNAc在TBP介导的细胞内的作用 基因表达。具体目标2：继续阐明OGT如何专门针对 上千种不同的蛋白质底物？假设：OGT达到高度特异性， 不仅通过其对肽序列的识别，而且通过其被辅助分子靶向底物， proteins.本研究将系统评价OGT结合伴侣的一般和特异作用 在OGT的活动对它的许多基板。 鉴于O-GlcNAc对慢性疾病机制的重要性，例如糖尿病中的葡萄糖毒性， 癌症和神经退行性变，阐明这些机制不仅是理解 转录和信号传导，也揭示了新的治疗途径。

The cycling of N-acetylglucosamine on Ser(Thr) residues (O-GlcNAcylation) of nuclear, cytoplasmic and mitochondrial proteins serves as a nutrient sensor to regulate signaling, transcription, and cellular physiology. Abnormal O-GlcNAcylation underlies the etiology of diabetes, cancer and Alzheimer's disease. O-GlcNAcylation regulates nearly every aspect of transcription, including RNA polymerase II, histones, DNA methyltransferases, and nearly all transcription factors. Yet we know very little about the mechanisms involved. TATA-binding protein (TBP) is amongst the most important components of the transcription machinery. Our recent studies indicate that TBP regulated by O-GlcNAcylation in response to nutrients. O-GlcNAcylation has extensive crosstalk with protein phosphorylation and other modifications. However, unlike phosphorylation, which is catalyzed by hundreds of kinases, there is only one highly conserved gene encoding O-GlcNAc transferase (OGT). Nonetheless, OGT site-specifically modifies thousands of proteins. Our data indicate that OGT's substrate specificity is not only determined by its specificity for peptide sequence, but also by its transient associations with other proteins, which dynamically target it to specific substrates. OGT targeting interactions are largely mediated by its tetratricopeptide repeats (TPRs). OGT missing TPRs remains active against small peptides, but has poor activity against full-length proteins. Herein we will investigate two major questions related to O-GlcNAcylation: Specific Aim 1: Continue to Study Glucose Regulation of TATA-binding protein (TBP) via its O-GlcNAcylation. Hypothesis: At certain promoters, glucose regulates TBP DNA-binding and its ability to bend DNA by altering its O- GlcNAcylation. We will systematically elucidate mechanisms and functions of this nutrient regulation of TBP. Three goals: A. Roles of O-GlcNAcylation in the molecular and cellular properties of TBP? B. Roles of O- GlcNAc in TBP's Interactions in the Transcription Cycle. C. O-GlcNAc's In Vivo Roles in TBP-mediated Gene Expression. Specific Aim 2: Continue to Elucidate How OGT is Specifically Targeted to Thousands of Different Protein Substrates? Hypothesis: OGT achieves a high degree of specificity not only by its recognition of peptide sequence, but also by it being targeted to substrates by accessory proteins. This Aim will systematically evaluate both the general and specific roles of OGT binding partners in OGT's activities toward its many substrates. Given O-GlcNAc's importance to mechanisms of chronic disease, such as glucose toxicity in diabetes, cancer and neurodegeneration, elucidation of these mechanisms will not only be key to understanding transcription and signaling, also to uncovering new avenues for therapeutics.