Nuclear activity of carnitine acetyltransferase

简介：乙酰辅酶A作为核-线粒体串扰的一种重要介质出现，并且有令人信服的证据表明，这种中心代谢物的可用性是通过调节特定蛋白质乙酰化反应，特别是染色质中组蛋白的乙酰化反应来调节细胞生长和增殖的关键调节剂。在我们研究精子细胞染色质重塑的过程中，我们观察到组蛋白的短暂高乙酰化与它们从染色质中被驱逐有关。然而，一个系统的质谱分析组蛋白相关的蛋白质没有产生潜在的组蛋白乙酰转移酶的候选人在这些步骤。然而，我们观察到一个几乎完全的核置换的线粒体肉毒碱乙酰转移酶（CrAT）通常发现在线粒体或过氧化物酶体在小鼠和人类。肉毒碱乙酰转移酶（CrAT）催化乙酰辅酶A自由可逆地转化为其膜渗透性肉毒碱酯乙酰肉毒碱。来自人类生殖细胞的RNA分析揭示了剪接变体，其中之一包括保留部分内含子，其引入早期框内终止密码子，迫使下游ATG转录，并编码缺乏线粒体定位信号的蛋白质，该蛋白质可能由于存在简并核定位信号（NLS）而具有核定位的潜力。转染实验表明，如果C-末端过氧化物酶体靶向序列（PTS）受阻，这种变体可以定位到细胞核。因此，CrAT的核定位可能会改变该隔室中的乙酰辅酶A库，从而允许细胞核中的酶促或非酶促乙酰化过程。在体细胞中，通过CrAT活性改变核乙酰辅酶A可能对遗传稳定性，诱变和aging.Hypothesis的重要后果：核寻址的CrAT影响染色质稳定性，通过乙酰化的组蛋白和其他nuclearproteins.Objectives的：我们的目标是调查调节核寻址的CrAT，并得到第一次深入了解其生物学作用。因此，今后五年的具体目标是：1.确定CrAT核表达对染色质和乙酰化酶2的影响。确定CrAT核寻址的序列和机制3。结论：这些实验步骤是我们研究计划的一部分，将确定核CrAT的功能，特别是，它是否参与染色质动力学和遗传稳定性。理解神经元-核串扰是神经退行性疾病、衰老和癌症的合理干预方法的关键。这将为HQP的培训提供一个激励性的研究环境。

Introduction:Acetyl-CoA emerges as one important mediator of the nuclear-mitochondrial crosstalk and compelling evidence indicates that availability of this central metabolite is a key regulator of cell growth and proliferation through modulation of particular protein acetylation reactions, especially those at histones in chromatin. During the course of our investigation on the chromatin remodelling in spermatids, we observed a transient hyperacetylation of histones associated with their eviction from the chromatin. However, a systematic mass spectrometry analysis of histone-associated proteins yielded no potential histone acetyltransferase candidate at these steps. However, we observed a near complete nuclear displacement of the mitochondrial carnitine acetyltransferase (CrAT) normally found in the mitochondria or peroxysomes in both mouse and human. Carnitine acetyltransferase (CrAT), catalyzes the freely reversible conversion of acetyl-CoA to its membrane permeant carnitine ester, acetylcarnitine. RNA analyses from human germ cells revealed splicing variants, one of which included retention of a partial intron that introduces an early in-frame stop codon forcing transcription from a downstream ATG and encoding a protein lacking the mitochondrial localisation signal that may have the potential for nuclear localisation owing for the presence of a degenerated nuclear localisation signal (NLS). Transfection experiments indicate that this variant can localize to the nucleus if the C-terminal peroxisomal targeting sequence (PTS) is hindered. The nuclear localization of CrAT may therefore modify the acetyl-CoA pool in this compartment allowing either enzymatic or non-enzymatic acetylation processes in the nucleus. In somatic cells, alteration of nuclear acetyl-CoA through the CrAT activity may have important consequences on genetic stability, mutagenesis and aging.Hypothesis:The nuclear addressing of CrAT impacts chromatin stability through acetylation of histones and other nuclear proteins.Objectives:Our goal is to investigate regulation of the nuclear addressing of CrAT and get the first insights into its biological role. Accordingly, the specific objectives for the next five years are:1. To determine the consequence of CrAT nuclear expression on chromatin and acetylome2. To determine the sequence and mechanism involved in CrAT nuclear addressing3. To determine the impact of CrAT on genetic integrity and DNA damage responseConclusion:These experimental steps are part of our research program and will define the function of nuclear CrAT, in particular, whether it is involved in chromatin dynamics and genetic stability. Understanding the mitochondrial-nucleus crosstalk is key for rational intervention approaches in neurodegenerative disorders, aging and cancers. This will provide a stimulating research environment for the training of HQP.