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Determination of the mechanism of the immunosuppressive effects of thiopurines

硫嘌呤免疫抑制作用机制的测定

基本信息

批准号：
8290672
负责人：
Jongyun Heo
金额：
$ 44.03万
依托单位：
UNIVERSITY OF TEXAS ARLINGTON
依托单位国家：
美国
项目类别：
财政年份：
2012
资助国家：
美国
起止时间：
2012-02-08 至 2016-01-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8290672
关键词：
6-Mercaptopurine 6-thioguanylic acid Acute Lymphocytic Leukemia Acute leukemia Address Adenocarcinoma Apoptosis Autoimmune Diseases Award Azathioprine Biochemical Cell membrane Cells Cellular biology Chemistry DNA Data Development Disulfides Drug Delivery Systems Elements Goals Grant Guanine Nucleotide Exchange Factors Guanine Nucleotides Guanosine Triphosphate Phosphohydrolases Immune System Diseases Immune response Immunosuppression Immunosuppressive Agents In Vitro Inflammatory Bowel Diseases Isomerism Kinetics Knowledge Lead Link Malignant Neoplasms Mediating Mismatch Repair Modeling Molecular Molecular Biology Nitric Oxide Oxidation-Reduction Pharmaceutical Preparations Proteins Regulation Research Role Science Students System T-Cell Activation T-Cell Proliferation T-Lymphocyte Therapeutic Thioguanine adduct analog base career chemotherapeutic agent cytotoxicity design direct application disulfide bond experience graduate student innovation inorganic phosphate interdisciplinary approach novel rac GTP-Binding Proteins rac1 GTP-Binding Protein rho therapy development thiopurine tumor undergraduate student

项目摘要

DESCRIPTION (provided by applicant): The research proposed will examine the chemistry-based cellular mechanism behind the inhibitory action of 6-thiopurine (6-TP) drugs such as 6-thioguaine (6-TG) and its isomers such as 8-thiogunaine (8-TG) on Rac1 GTPase and its implication in T-cell inactivation. 6-TP analogs are important chemotherapeutic agents in the treatment of autoimmune disorders and various tumors, including acute leukemia and adenocarcinomas. One of therapeutic actions of 6-TP drugs for acute leukemia is to activate the DNA mismatch repair system, which results in induction of cell apoptosis. Recent studies show that the therapeutic action of 6-TP drugs in certain immune disorders is to induce immunosuppression by blockage of Rac1 activation in T lymphocytes. However, a clear mechanism of action of 6-TP drugs associated with Rac1 as an immune disorder chemotherapeutic is yet to be determined. We hypothesize that 6- or 8-TG is cellularly converted into a 6- or 8-thioguanine nucleotide (6- or 8-TGNP) that targets Rac1 to form a disulfide adduct between 6- or 8-TGNP and the redox-sensitive GXXXXGK(S/T)C motif of Rac1. This Rac1-6- or -8-TGNP adduct inactivates T cells; and a redox agent is required for the formation of the Rac1-6- or -8-TGNP adduct. Although our preliminary study results have provided critical information about the action of 6-TP and 8-TG drugs in T cells, we lack several important elements necessary to a better understanding of the effect(s) of 6- TP and 8-TG drugs on Rac1 and T cell inactivation. For example, no clear explanation has been elucidated for the detailed molecular mechanism that governs the role of the redox agent on the 6- or 8-TP-mediated inhibition of Rho protein via formation of the Rac1-6- or -8-TGNP disulfide adduct. To better understand the TP-mediated inactivation of Rac1 via formation of the Rac1-6- or -8-TGNP adduct associated with a redox agent and its implication in cells, we propose a detailed mechanistic study using kinetic and mass spectrometric analyses as well as molecular and cell biology approaches. The anticipated results of our proposed study will provide the basis for development of a better immunosuppressive agent(s) to target and inactivate Rac1. Given that the rate of apoptosis of cells treated with 8-TG was minimal compared with that of 6-TP, analogs of 6-TP - including 8-TG - may be superior to those of 6-TP for drugs that target Rac1 with less cytotoxicity than what is encountered with 6-TP. PUBLIC HEALTH RELEVANCE: This proposed research seeks to understand the Rac GTPase-targeting action of thiopurine drugs in vitro and in T cells. This action may suppress T-cell activation, thereby suppressing certain immune responses. The anticipated results of our proposed study may lead to a molecular and mechanistic basis for developing therapies for immune disorders, such as Inflammatory Bowel Disease, that are associated, at least in part, with abnormal regulation of Rac proteins.

描述（由申请人提供）：拟进行的研究将检查6-硫嘌呤（6-TP）药物（如6-硫鸟嘌呤（6-TG）及其异构体（如8-硫鸟嘌呤（8-TG））对Rac 1 GTdR的抑制作用背后的基于化学的细胞机制及其在T细胞灭活中的意义。6-TP类似物是治疗自身免疫性疾病和各种肿瘤（包括急性白血病和腺癌）的重要化疗剂。6-TP药物对急性白血病的治疗作用之一是激活DNA错配修复系统，诱导细胞凋亡。最近的研究表明，6-TP药物在某些免疫疾病中的治疗作用是通过阻断T淋巴细胞中Rac 1的活化来诱导免疫抑制。然而，与Rac 1相关的6-TP药物作为免疫疾病化疗剂的明确作用机制尚未确定。我们假设6-或8-TG在细胞内转化为靶向Rac 1的6-或8-硫代鸟嘌呤核苷酸（6-或8-TGNP），以在6-或8-TGNP与Rac 1的氧化还原敏感性GXXXXGK（S/T）C基序之间形成二硫键加合物。该Rac 1 -6-或-8-TGNP加合物使T细胞失活;并且Rac 1 -6-或-8-TGNP加合物的形成需要氧化还原剂。尽管我们的初步研究结果提供了关于6-TP和8-TG药物在T细胞中作用的关键信息，但我们缺乏更好地理解6- TP和8-TG药物对Rac 1和T细胞失活的影响所必需的几个重要因素。例如，尚未阐明氧化还原剂通过形成Rac 1 -6-或-8-TGNP二硫键加合物对6-或8-TP介导的Rho蛋白抑制作用的详细分子机制。为了更好地了解TP介导的Rac 1的失活，通过形成Rac 1 -6-或-8-TGNP加合物与氧化还原剂及其在细胞中的含义，我们提出了一个详细的机制研究，使用动力学和质谱分析以及分子和细胞生物学方法。我们提出的研究的预期结果将为开发更好的免疫抑制剂提供基础，以靶向和抑制Rac 1。考虑到用8-TG处理的细胞的凋亡率与6-TP相比是最小的，6-TP的类似物-包括8-TG -对于靶向Rac 1的药物而言可能比6-TP的类似物更上级，其细胞毒性比6-TP所遇到的更小。公共卫生相关性：这项拟议的研究旨在了解硫嘌呤药物在体外和T细胞中的Rac GT酶靶向作用。这种作用可以抑制T细胞活化，从而抑制某些免疫反应。我们提出的研究的预期结果可能会导致开发免疫疾病（如炎症性肠病）治疗的分子和机制基础，这些疾病至少部分与Rac蛋白的异常调节相关。

项目成果

期刊论文数量（6）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Kinetic mechanisms of mutation-dependent Harvey Ras activation and their relevance for the development of Costello syndrome.

DOI：
10.1021/bi400679q
发表时间：
2013-11-26
期刊：
BIOCHEMISTRY
影响因子：
2.9
作者：
Wey, Michael;Lee, Jungwoon;Jeong, Soon Seog;Kim, Jungho;Heo, Jongyun
通讯作者：
Heo, Jongyun

Superoxide inhibits guanine nucleotide exchange factor (GEF) action on Ras, but not on Rho, through desensitization of Ras to GEF.

DOI：
10.1021/bi401528n
发表时间：
2014-01-28
期刊：
Biochemistry
影响因子：
2.9
作者：
Wey M;Phan V;Yepez G;Heo J
通讯作者：
Heo J

Allosteric autoactivation of SOS and its kinetic mechanism.

DOI：
10.1080/21541248.2019.1601954
发表时间：
2021-01-01
期刊：
Small GTPases
影响因子：
0
作者：
Hoang, Hanh My;Umutesi, Hope Gloria;Heo, Jongyun
通讯作者：
Heo, Jongyun

Development of Noonan syndrome by deregulation of allosteric SOS autoactivation.

变构 SOS 自动激活失调导致努南综合征的发生。

DOI：
10.1074/jbc.ra120.013275
发表时间：
2020
期刊：
The Journal of biological chemistry
影响因子：
0
作者：
Umutesi,HopeGloria;Hoang,HanhMy;Johnson,HopeElizabeth;Nam,Kwangho;Heo,Jongyun
通讯作者：
Heo,Jongyun

Rac-dependent feedforward autoactivation of NOX2 leads to oxidative burst.