ALDH Activation to treat Fanconi Anemia

项目总结 范可尼贫血(FA)是由至少19个FA互补(FANC)组基因中的一个突变引起的， 它们是修复DNA链间交链(ICL)所必需的。FA患者有先天畸形， 造血干细胞(HSC)损伤导致骨髓衰竭易感性增加(严重 再生障碍性贫血(再生障碍性贫血：再生障碍性贫血)和白血病，对化疗和放射的敏感性增加，以及 继发性癌症，即使成功地通过造血干细胞移植治疗再生障碍性贫血或 白血病。因为FA潜在的突变会影响到体内的每个细胞，所以目前还没有治愈FA的方法。 最近的研究表明，icl是由乙醛等活性醛引起的。 (回声)。乙醛脱氢酶(ALDH)家族的氧化作用使醛脱毒。在东方 亚洲，乙醛脱氢酶2(ALDH2)基因的一个高度流行的点突变导致 半显性功能丧失，氧化高反应性回声的能力降低。暴露于MECHO 通过内源性途径、外源性摄入或吸入发生的，或作为主要的 乙醇(Etoh)代谢产物。ALDH2*2突变导致众所周知的“亚洲潮红” “综合征”的特征是摄入少量乙醇后出现双硫仑样反应。ALDH2*2 突变还会增加癌症的易感性，特别是食道癌。因此，ALDH2和 FA DNA修复途径提供了两层基因组保护，使其免受MECHO的毒性影响。人类和 两种途径双突变的小鼠由于HSC的丢失而迅速发展成骨髓衰竭。我们的 对带有人类ALDH2*2突变的小鼠的分析表明，即使是在小鼠的ALDH2等位基因上 在基本环境中，(没有接触乙醇)HSC 1)逐渐丧失，2)在竞争中 对正常的HSC不利，以及3)具有典型的对干扰素的反应的基因表达谱， 是已知的干细胞自我更新的抑制因子。初步结果还表明，接触乙醇会导致 野生型(ALDH2*1/*1)小鼠的HSC数量显著下降。我们已经开发了ALDH激活剂 (ALDAs)，增加ALDH2*1和ALDH2*2活性的小分子，或重定向其他ALDH 家族成员，例如ALDH3a1，也氧化MECHO。为了测量细胞的醛负荷，我们还 制造了独特的基于荧光的传感器，可以用于单个细胞的流式细胞仪分析， 例如，HSC。在这项资助中，我们将测试ALDAs可以通过以下方式保护FA HSC免受遗传毒性损伤的假设 减少了反应性醛的负荷。我们将研究FANCD2和FANCD2双重突变的小鼠模型 ALDH2*2为确定ALDH2激活的保护作用，测量ALDAs对醛的影响 并确定ALDH3a1在MECHO代谢中的募集是否保护HSC。这些 临床前研究有可能迅速转化为急需的临床试验，旨在预防 FA患者的SAA、白血病和癌症。

PROJECT SUMMARY Fanconi anemia (FA) is caused by mutations in one of at least 19 FA complementation (FANC) group genes, which are required to repair DNA interstrand cross links (ICL). Patients with FA have congenital anomalies, hematopoietic stem cell (HSC) injury resulting in increased susceptibility to bone marrow failure (severe aplastic anemia: SAA) and leukemia, increased sensitivity to chemotherapy and radiation, and high risk of secondary cancers, even if they are successfully treated by HSC transplantation for their aplastic anemia or leukemia. Because the mutations underlying FA affect every cell in the body, there is currently no cure for FA. Recent studies have demonstrated that ICL are caused by reactive aldehydes, such as acetaldehyde (MeCHO). Oxidation by the aldehyde dehydrogenase (ALDH) family of enzymes detoxify aldehydes. In East Asia, a highly prevalent point mutation in the Aldehyde Dehydrogenase 2 (ALDH2) gene causes a semidominant loss of function, and decreased ability to oxidize highly reactive MeCHO. Exposure to MeCHO occurs through generation by endogenous pathways, exogenous ingestion or inhalation, or as the major product of ethanol (EtOH) metabolism. The ALDH2*2 mutation results in the well-known “Asian flushing syndrome” marked by a disulfiram-like response to ingestion of small amounts of EtOH. The ALDH2*2 mutation also results in increased susceptibility to cancer, especially esophageal cancer. Thus, the ALDH2 and FA DNA repair pathways confer two tiers of genome protection from the toxic effects of MeCHO. Humans and mice doubly mutated for both pathways rapidly develop bone marrow failure due to the loss of HSC. Our analyses of mice with a knock-in of the human ALDH2*2 mutation at the murine ALDH2 allele show that, even in a basal environment, (without exposure to EtOH) HSC are 1) progressively lost, 2) at a competitive disadvantage to normal HSC, and 3) have a gene expression profile typical of a response to interferons, which are known inhibitors of stem cell self-renewal. Preliminary results also indicate that EtOH exposure causes significant decline in HSC numbers in wildtype (ALDH2*1/*1) mice. We have developed ALDH activators (Aldas), small molecules which increase the activity of both ALDH2*1 and ALDH2*2, or re-direct other ALDH family members, e.g., ALDH3a1, to also oxidize MeCHO. To measure the cellular aldehydic load, we have also made unique fluorescence based sensors, which can be used in flow cytometric analyses of individual cells, e.g., HSC. In this grant we will test the hypothesis that Aldas can protect FA HSC from genotoxic injury by decreasing the load of reactive aldehydes. We will study murine models doubly mutated for FANCD2 and ALDH2*2 to determine the protective effect of ALDH2 activation, measure the effects of Aldas on aldehydic load in HSC, and determine whether recruitment of ALDH3a1 to MeCHO metabolism protects HSC. These pre-clinical studies have the potential to rapidly translate to much needed clinical trials aimed at prevention of SAA, leukemia and cancer in patients with FA.