Summary

细胞和组织中辅酶A的定量

Published: September 27, 2019
doi:

Summary

该方法描述了来自培养细胞和动物组织的样品制备,在样品中提取和衍生辅酶A,然后高压液相色谱用于纯化和定量衍生辅酶A吸光或荧光检测。

Abstract

最新研究表明,细胞辅酶A(CoA)供应可能受到限制,对生长、新陈代谢和生存产生不利影响。细胞CoA的测量是一个挑战,由于其相对较低的丰度和自由CoA的动态转换到CoA硫化物,反过来,参与大量的代谢反应。介绍了一种方法,该方法在样品制备过程中通过潜在缺陷进行导航,以产生适用于许多生物医学实验室的广泛线性检测范围的检测。

Introduction

辅酶A(CoA)是所有生物中必不可少的合成物,由泛酸(也称为泛酸盐)或维生素B5合成。CoA是有机酸的主要细胞内载体,包括短链酸,如醋酸和琥珀酸,亚链酸,如丙酸和甲基甲酸酯,长链脂肪酸,如棕榈酸和油酸盐,超长链脂肪酸,如多不饱和脂肪酸,异种生物,如丙丙酸。有机酸与CoA酶形成硫酯联联系,使其在100多个中间代谢1反应中用作基质。CoA 硫化物也是基洛斯特调节剂和转录活化剂。现在,人们赞赏2,细胞总CoA供应是调节3,4;因此,CoA的可用性可以受到限制,CoA的缺陷可能是灾难性的,例如影响CoA生物合成5的遗传性遗传性疾病。泛酸激酶催化CoA生物合成的第一步(图1)和泛酸激酶相关神经退化,称为PKAN,是由PANK2基因6的突变引起的。CoA合成酶,由COASYN基因编码,催化CoA生物合成的最后两个步骤(图1)和COASY蛋白相关的神经退化,称为CoPAN,是由COASYN基因7的突变引起的。PKAN 和 CoPAN 都是遗传性神经退行性疾病,与大脑中的铁积累和 CoA 缺乏疾病病理学有关。

在组织8之间,总 CoA 的细胞水平各不相同,在各种生理、病理和药理状态下,总 CoA 可以增加或减少。肝CoA增加期间燃料从饲料切换到禁食状态9,肝CoA水平异常高的瘦素缺乏肥胖小鼠10。肝CoA减少对慢性乙醇摄入11。Pank2敲除小鼠模型中的脑CoA水平在围产期被抑制,但后来在成人阶段大脑CoA含量相当于野生型水平,表明在发育过程中有自适应CoA反应。通过转因或基因传递方法操作组织CoA含量会影响代谢和神经功能13、14、15。PKAN 或 CoPAN 潜在疗法的临床前开发包括细胞或组织 CoA 测量作为疗效指标 16、17、18、19、20.评估所有这些条件及其代谢或功能后果需要一种定量方法来测量总 CoA。

在许多实验室中,测量生物样品 CoA 的准确、可靠的检测是一项技术难题。不幸的是,没有探针可用于评估或量化在完整细胞中的CoA或CoA硫化物,虽然天然CoA硫化物的类比在利用酶21的CoA酯研究中被广泛用作机械探针。CoA 与游离磺酸 (-SH) 莫伊蒂一起转换为 CoA 硫化物(反之亦然)在转移到不同环境和细胞裂解期间在细胞或动物组织中快速。细胞中的大量丙基-CoA合成酶和丙基-CoA硫酯酶在CoA池内介导转化,利用CoA硫酯作为基质的其他酶在生物样品中保持活性,直到通过化学或物理淬火意味 着。通过丙烯转移酶将丙基组从CoA卸载到肉碱,是反应网络中可能改变CoA/CoA硫酯分布的一个例子。放射性示踪剂可用于测量细胞中的CoA合成率。目前测量生物样品中的CoA和CoA衍生物的方法已经审查了22种,包括耦合酶分光度测定测定、高压液相色谱和质谱法程序。然而,这些方法往往集中在特定的CoA分子物种上,并且对整个CoA池的变化视而不见。由于检测灵敏度低,并且线性范围有限,耦合酶测定通常需要大量输入材料。

我们的实验室已经开发出一种可靠的程序,用于定量培养细胞和动物组织中的总CoA。该战略包括所有CoA硫化物的水解,在样品制备过程中只产生免费CoA,而不是努力维持和分析CoA物种的整个谱系。该程序是单独公布的方法汇编,用于制备样品、CoA衍生、纯化和高压液相色谱 (HPLC) 后识别,以及通过吸光或荧光检测23,24,25。使用此程序获得的 CoA 测定使我们能够了解 CoA 法规,并开发治疗 CoA 缺陷的治疗方法。

Protocol

本议定书中提到的动物程序是按照第323和556号议定书进行的,并特别得到圣朱德儿童研究医院机构动物护理和使用委员会的批准。 1. 准备解决方案 注:使用超纯水用于所有解决方案,并在程序中注明。 在水中制备1 mM氢氧化钾(KOH)。 在水中准备 0.25 M KOH。 在水中准备 1 M Trizma-HCl 并调节到 pH 8.0。 在醋酸酯(Optima级)中制?…

Representative Results

利用mBBr将CoA的二醇衍生为荧光剂,然后利用反相HPLC纯化衍生的CoA-bimane,开发出一种相对快速、可靠的方法,用于检测培养细胞和组织的总CoA。首先生成标准曲线,其中已知且不断增加的 CoA-bimane 标准量单独注入,CoA-bimane 色谱图中峰值下的区域绘制为输入 CoA-bimane 的函数(图 4)。CoA-bimane 的吸收率最大值为 ±393 nM ,具有代表性的 HPLC 配置文件使用表 1中的洗?…

Discussion

在这里,我们演示了一个可靠的、分步化的过程,用于量化细胞和动物组织中的总 CoA,具有广泛的线性检测功能,这些线性检测可在具有吸收性或荧光输出检测器的 HPLC 的实验室中进行。或者,质谱法是评估CoA和CoA硫化物的常用技术,但由于仪器的成本以及开发方法和解释数据所需的专业知识,因此不能广泛提供。适合用作质谱中自由 CoA 定量的内部标准的同位标记 CoA 不可用于商业上,并且仪?…

Declarações

The authors have nothing to disclose.

Acknowledgements

作者承认,由BridgeBio LLC的子公司CoA治疗公司、国家卫生研究院拨款GM34496和美国黎巴嫩叙利亚联合慈善机构提供的赞助研究提供资金。

Materials

2-(2-pyridyl)-ethyl silica gel SPE column Millipore-Sigma 54127-U
coenzyme A Avanti Polar Lipids 870700
Gemini C18 3 μm 100 Å HPLC column Phenomenex 00F-4439-E0
monobromobimane ThermoFisher Scientific M-1378
Omni-Tip probe tissue disrupter Omni International 32750H
Parafilm Fisher S37440
PowerGen 125 motorized rotor stator homogenizer ThermoFisher Scientific NC0530997
Spin-X centrifuge tube filter CoStar 8161
Trizma-HCl Fisher T395-1
Waters 2475 fluorescence detector Waters 2475
Waters 2489 UV-Vis detector Waters 2489
Waters e2695 separations module Waters e2695

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Frank, M. W., Subramanian, C., Rock, C. O., Jackowski, S. Quantification of Coenzyme A in Cells and Tissues. J. Vis. Exp. (151), e60182, doi:10.3791/60182 (2019).

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